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Michael G
13th Feb 2016, 09:42 PM
I've been asking enough odd questions now that some people have twigged that I've got something on the go, so I though I'd start the thread just so that people trying to answer the questions I'm posing have some background.
This is a spin off of the Jones & Shipman rebuild - just like generals equip to fight the last war, I'm equipping based on the problems I've had. The key is this photo -
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While it did the job, it was a close run thing as I nearly ran out of room to clamp the sine table on the R/T. The other issue was that it was fixed with respect to the centre of rotation so things could not be moved easily off centre (or to put it another way, the only eccentric in the shed was me...)
At first I though I might make a scaled down version of my sine table but I did not like the links sticking up on the side. There are ways around this but none of them really appealed.
Scanning the web as you do I saw all sorts of angle plates but a lot of the newer ones were only say 45 degrees either way from flat. Then I saw an offering from Yuasa - their 550-403. Able to rotate from vertical through horizontal to about -30 degrees the other way.
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As I've said before, with the advent of CNC a lot of the fixturing tooling that used to be used has disappeared - why do you need an X-Y table on a rotary table if the program can make the moves instead? True to this paradigm, these plates don't appear to be made anymore, either under the Yuasa name or NEWS (the previous name for their gear). However, it would not have mattered much as the table on that model is 10" long so based on these proportions it was unlikely to fit.
Make a smaller copy? A block of CI for the base would cost around $150, 2/3rds of it would become swarf and it would take some time to reduce the 24kg block down.
I then thought casting. Using my rapidly atrophying woodworking skills, I put a pattern together for one that should have a table surface 8"x5" (roughly). For those of you who have not had much to do with pattern making, the key word is draft (followed by shrinkage). The trough pieces have a 3 degree taper top and bottom. The round base is similar, having effectively a conical top and bottom. Lots of filler too.

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Currently the completed pattern is with Castech here in Adelaide who will cast it for me some time in the next few weeks.
This is where this thread comes in -
http://metalworkforums.com/f65/t198823-question-metrologicly-minded
Once the bottom is machined off flat, I need to put a cylindrical profile in that trough. It needs to be close to 62.5mm radius and for strength as well as aesthetics, I need the centre of the bore to be concentric with the outer surface of the casting. With the non-uniform surface of a casting as the only thing to use as a starting point, an interesting problem.

Michael

Pete F
13th Feb 2016, 10:20 PM
With the non-uniform surface of a casting as the only thing to use as a starting point, an interesting problem.

If it were me, during this design phase I would determine a point on the casting that was a machined master datum point and, either directly or indirectly, reference all features back to that. It may be an existing feature or, if none were suitable, you could create a specific point. Otherwise you could finish up either chasing your tail with accumulated errors, and/or needing unnecessarily complicated measuring and techniques.

jhovel
13th Feb 2016, 10:41 PM
Whoa! I'm looking forward to that casting arriving at your place and following this thread!
Obviously no level of complexity stops you. I like it.

Michael G
14th Feb 2016, 08:55 AM
If it were me, during this design phase I would determine a point on the casting that was a machined master datum point and, either directly or indirectly, reference all features back to that.

Fear not Pete - I have... a plan! :o (pauses for dramatic music)



One of the problems with a first off casting is that while it should be like the pattern, there may be some slight differences (a trained pattern maker would probably allow for this - me being an amateur, I use the 'suck it and see' method). As an example, it will be harder for heat to get away from the inside of that cylindrical shell than on the outside, so I would expect the outside to solidify first and then the inside. That may tend to curl the ends in a little but could be counter balanced by the large blob of molten stuff underneath (the cylindrical boss will be the last bit to solidify but is also the fill point).
Once I have it I will be able to see how much it has moved from the pattern and adjust my method accordingly.

So far the sequence is to

Machine the base off flat, positioning it on the mill so that the outside surface of the ends of the trough are equidistant from the table and the front and back edges of the base are also level
Using a dial indicator run along the inside of the trough and find the lowest point at several places along the casting. Join these to be a line and then align that to the axis of the mill. Do a cut along the back of the trough (ie the handle side) to provide a datum surface and machine the ends of the trough at 90 degrees to establish another datum.
Leave in the shed overnight for the magical elves to finish it off Use a probe to pick up on the outside surface of the trough to establish a radius. The 'line of lowest points' should have established the centre fore-aft; a radius should allow the axis to be fixed vertically. Machine the top surface of the trough to put a surface at the same height as the axis. Using a boring head clean up the inside of the trough.
Drill/ bore most of the material from the screw cavity.
At this stage because I've taken the skin off one side of the casting but not the other I'll try to leave it for a bit and let it relax. (if I have the patience)
After letting it settle it is a matter of resetting datums, finish machining things and getting everything to size.



This sequence is using the casting as the frame of reference - I haven't worked out exactly how I will be holding it at the moment. I would like to do it all with the vertical head on the mill as not as many have a horizontal spindle to play with. One of the reasons for a casting was that I was sure that sooner or later someone would want to make one too.

Michael

Pete F
14th Feb 2016, 11:42 AM
How much are you expecting the casting to differ from the pattern? I would have expected it to be reasonably close (obviously in non-precision terms) once shrinkage is allowed for.

I would definitely stress relieve this before machining as you're taking material off in various different areas. I'm currently finishing a longer straight edge that wasn't stress relieved but rested for a few years after rough scraping and it moved a lot. It still is moving, so I will stress relieve it with vibration.

My point about establishing a master datum is that can be checked for parallel/perpendicularity/specific angle/specific position/etc as required before each machining op. Just sequentially machining on a part like this I fear could allow your tolerances to stack to the extent that it's possible it won't fit a mating part correctly. Even after stress relieving, I'd still expect the casting to move considerably when asymmetrically machining the casting.

Michael G
14th Feb 2016, 08:13 PM
How much are you expecting the casting to differ from the pattern? I would have expected it to be reasonably close (obviously in non-precision terms) once shrinkage is allowed for.
I agree - This is the first casting I've done with thin-ish unsupported sections so I'm really guessing what it will do but I know from experience with injection mouldings that they can move a bit on cooling when made like that so I'll have to wait and see.


I would definitely stress relieve this before machining as you're taking material off in various different areas. I'm currently finishing a longer straight edge that wasn't stress relieved but rested for a few years after rough scraping and it moved a lot. It still is moving, so I will stress relieve it with vibration.

These guys are good, in that they let the parts cool in the mould (none of this break them out and put hot parts in a tub of water 'cause we're in a hurry). Previous castings I got from Castech were very nice to machine - no hard spots.

Understand what you are saying about datums although the only really critical part in terms of fit will be the inside of the cylinder. All the rest is establishing flat surfaces to allow clamping/ set up/ offset . When I pick up I'll talk to them about how best to stress relieve. I was going to leave a little extra when I first machine just in case it does move. I have roughly 3mm machining allowance on it so figure I can take a mm or two off, let it relieve and come back to re establish my surfaces.

I have time to let it sit though as I need to sort out tooling for the other bits yet. Rather than cast the rotating piece I was going to machine from solid as I have a piece of steel sitting here that is just the right size.

Michael

DSEL74
15th Feb 2016, 09:04 AM
It's a very long time since I spent time in the foundry. I can't help on the machining side. But in relation to you concerns about the cooling and cupping of the casting the foundry should plan for that with locations of sprues and risers etc allowing for the thin sections to pull material back from those rather than have a shrink in the heavy section. Chills can also be incorporated if required in some cases. If your not happy question them and reject the part and make them do it again.

KBs PensNmore
15th Feb 2016, 11:22 PM
Hi Michael,
I have this available for you, if it's of any use. The diameter of the T slot is 80mm Centres and the top is 100 diameter.
Centre pin is approx 25mm and the base is approx 20mm thick.
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Kryn

Michael G
16th Feb 2016, 07:01 AM
Thanks Kryn. I'll bear it in mind. An 80mm PCD may be too small for the casting but until I get it back I can't check. I have a bad habit of doing a drawing, half making to it, then changing my mind but not going back to alter the drawing - as a result checking the drawing/ sketch I have won't tell me much.:doh:

One of the issues I had with commercial plates is that they did not allow the angle plate surface to be positioned with respect to the centre of R/T rotation. I was thinking about a base plate with slots in it to allow that movement. Again, it will have to wait until the casting is back

Michael

Mike4
19th Feb 2016, 05:44 PM
Would it be possible to have two pieces of steel curved , stress relieved , machine as required .

I have had 1" thick 8 inch dia ,semi circles curved and before machining the mounting slot in each they were put in an oven for a day at a reasonable temperature to try to minimise movement during machining .


Another way is to find a piece of hollow bar and split it , yes its expensive to purchase.

Michael

Michael G
19th Feb 2016, 07:30 PM
I did think about the hollow bar route, and then the machining from solid route but a few of the guys suggested casting
http://metalworkforums.com/f65/t198732-6-hollow-bar

I spoke to the foundry today and the casting is a week or two away. I asked about stress relieving and the response was that because the casting was basically a lump (that is, not a flat thin part where the edges will cool way before the middle), it is unlikely to have too much internal stress build up. Guess I'll have to see.

Michael

Michael G
3rd Mar 2016, 07:23 PM
It's here. As much as I'd like to, I won't have time to do much (anything?) to it this weekend. Looks reasonable though and does not seem to have distorted at all compared to the pattern.
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Michael

KBs PensNmore
3rd Mar 2016, 10:14 PM
Hi Michael, looks good, be interesting to see what the weight is after the machining is done. Can drop the base in next week for you to to go over if required.
Kryn

jhovel
4th Mar 2016, 02:46 AM
It's here. As much as I'd like to, I won't have time to do much (anything?) to it this weekend. Looks reasonable though and does not seem to have distorted at all compared to the pattern.

Michael

Looking good Michael!
I look forward to seeing your machining set-ups and fixtures, as they are always educational and interesting.

Michael G
4th Mar 2016, 06:58 AM
I look forward to seeing your machining set-ups and fixtures, as they are always educational and interesting.

Hmm. Not sure whether 'educational and interesting' is good or bad. The sequence will be as I've outlined above but I'm still debating with myself exactly how to set up. I did think of restricting myself and using only the vertical spindle for those without a horizontal spindle (not that I'll necessarily use it) but there's probably little point as the same argument could be made about not having large boring heads etc.


...be interesting to see what the weight is after the machining is done. Can drop the base in next week for you to to go over if required.

My back of an envelope calculation was that it would be around 7.5kg, so I'll be interested too. At the moment there is extra material due to draft and machining allowances.
Still thinking about a base. I suspect a final decision will be months away. I'm still to work out what practical advantage it would give. Only very slight I suspect and if I strap it onto a rotary table I have a far more precise base than the Yuasa version.

Michael

Michael G
6th Mar 2016, 03:29 PM
Even though it is stinkingly hot here (39 ish) I could not resist the siren call of a fresh casting, so I did the first two steps I outlined.
First up was machining a flat surface on the base - although it would be nice to get it spot on, the aim is just a flat surface that can be clamped to a table. The ends as per the pattern were parallel, so offered an easy clamping solution - but as can be seen from the first photo it has been fettled back. Not sure why but it destroyed the parallel surface theory. I still held it in the same way that I intended to but approached it a good deal more cautiously. The second photo shows the method from the machine side - two angle plates tied together with hold down kit bits (with joining nuts!), and positioned front to back to be 'level' and side to side to be the same distance down from the edge of the plates
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Once done I could then flip over and clamp to the table. I did not quite get the side to side spot on so there is a 1mm shim under one side to correct. Next step was to find the low point of the trough.
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I adjusted the casting to get that parallel to the table and then machined the top edge to give a working datum (and not shown, a pass along the back to establish square that way)
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Last of all today, a pass down the ends to get them square to the top edge. As you can see the cutter I was using was not quite long enough to reach - some hand work for later.
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Next step according to the plan is 'Leave in the shed for the magical elves to finish off'. If those guys don't show up, next weekend hopefully I can find the bore axis and do a clean up cut.
Today's machining took the casting weight down to 8.1kg

Michael

Steamwhisperer
7th Mar 2016, 05:51 AM
Hi Michael
just wondering if you will be putting any 'marking-out' lines in before machining or is there plenty to machine off.
Did I say I wanted to come and live at your house. You get to do all the fun stuff. :D

Phil

Michael G
7th Mar 2016, 07:01 AM
This is just the first pass - establishing surfaces for reference. There is another 1 to 2mm to come off on most surfaces although there is the odd mark here and there to help out. One of the reasons for machining the top and back of the trough early on was to establish some references so that if something moved I hadn't lost datum. As with the last time I attacked a casting I keep worrying that there is not enough material there. Although it was not mentioned when I picked the casting up I think the pattern was not properly assembled in the mould as there seems to be a bit of misalignment between the two halves and lots of fettling around the parting line. Just enough to make things 'interesting'.
As for the fun stuff, I keep having people pop up with jobs they would like machined. Who am I to turn down the opportunity to practice on other people's material? On the go at the moment I have a couple of things for my TAD work as well as the J&S and the other day I was asked to see if I could sort out a set of inlet air bell mouths for an engine rebuilder. I'm still waiting for a guy to send me details of a special valve that I've said I'd make for him too...

Michael

Steamwhisperer
8th Mar 2016, 05:50 AM
I'm still waiting for a guy to send me details of a special valve that I've said I'd make for him too...

Michael
Apologies Michael but as you have probably guessed by now I'm not too flash in that area. :- (I am onto it)
The reason I asked about 'marking-out' was that my understanding is that it was done to make sure the casting is capable of getting to the finished product and so that roughly the same amount of 'skin' was machined off to minimise movement after machining although in my head the section of the casting would have more bearing on movement than skin.
Perhaps it is just that I am stuck permanently in the past now. :D

Phil

Michael G
8th Mar 2016, 07:17 AM
No - understand what you mean with respect to marking out. One of the problems I have a the moment is the most important bit is the trough bore axis and I don't know precisely where that is at the moment. When making up the pattern I allowed at least 3mm machining allowance on all the faces, so provided I don't go overboard in my roughing out I should be fine. To date machining has only been to get some square surfaces with clean up just enough to remove the skin (except for the ends), although with draft that can be a lot in places - 3 degrees over 100mm is 5.24mm.
The plan now will be to measure some coordinates around the outside of the trough, throw those into a spreadsheet and have that calculate a centre axis position for me. Once I have that I will clean that feature up but just as importantly I can go back and do some finish cuts so that everything is square/ parallel to that.

Prior to putting a DRO on the mill a lot of the machining that I did was to lines - the dials got used if the dimension had to be better than say +/-0.2mm or critical but typically I would be making something flat or parallel, putting in a slot or so on, but mainly that would involve measuring and then winding in the difference. Even cutting gears I would measure the blank with a caliper, find the point of cutter touch and then feed to the depth of tooth.
I still do lots of stuff in that relative way - perhaps 75% (it may sound funny but most of the time the DRO is off and folded back against the machine), but I find that the DRO helps keep track of longer dimensions so for jobs like this I will zero it to the datum surfaces and then work off that.

Once I have the bore to size everything else becomes relative to that, so then traditionally marking out would be done - but with a DRO that can be done in a virtual fashion. There will still be some marking involved but not so much.

Michael

PDW
8th Mar 2016, 08:33 AM
FWIW, an adjustable angle plate I made up years ago. Getting used to cut 45 deg slices off of a CI bar so I can make dovetail spotting masters.

The thing is 400mm long between trunnions because that was the max X travel on the mill I had at the time.

There are design flaws but it's worked pretty well over the years.

PDW

.RC.
8th Mar 2016, 10:04 AM
FWIW, an adjustable angle plate I made up years ago.

Any more pictures of the angle plate?

That cast iron bar looks the same size as the piece I have ;)

You have not collected those vials yet either.

PDW
8th Mar 2016, 05:05 PM
Any more pictures of the angle plate?

That cast iron bar looks the same size as the piece I have ;)

You have not collected those vials yet either.

Yeah I'll dig up a few more pix. Still have the patterns floating around here somewhere. If I was making more I'd make some slight changes to the main pattern and refine down the end pieces but it's not too bad. Does what I need it to anyway.

Tomorrow is post office day. I can't be bothered going more than once a fortnight or so. I'll get the vials then along with whatever else has turned up.

PDW

Michael G
12th Mar 2016, 06:41 PM
Today was a boring day - I was in the shed for around 6 hours today, was only doing one thing and still did not finish it...

I had grand plans for being able to measure the outside curve, use a spreadsheet to determine the radius and centre points line everything up and away I would go. I soon discovered after measuring that a) I had a lumpy bumpy casting and b) I did not have the precision to measure the curve properly. I could have set up the Isoma but a lot of stuffing around which I was trying to avoid.
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Instead, inspired by Phil's comment (about 5 up) I went Old School. For those not in the know, prior to digital and touch probes, bores and other features in castings were marked out with scribers, rules and calipers to determine position. For the centre of a hole, a wooden plug was used. In my case I only had a 1/3 of a hole so pulled out the trusty chain grips, used them to hold a block in the right spot and proceeded to find the centre. For ease of my reference I've put a coloured dot on each end of the casting. So, the red end first (two photos) and then the blue end.
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The centre position was tighter than I though it would be. I do need to sharpen my spring calipers though.
With the arc marked, I lined things up on a convenient riser block, put the mill head over 90 degrees and using the longest extension that I have for the Wohlhaupter proceeded to bore. Not as easy as all that. I had to break down and remake the set up 3 times as well as swap tips before things worked - The set up was a bit ticklish as it was right on the edge of my mill's envelope (literally). As it is the boring head at full feed only clears the end of the R/T by 5mm.
Speed was 40 rpm...
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Anyway, a start, 80% clean up and full clean up photo

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According to the 3 roller method I'm currently about 1mm in radius off target, so I should be able to finish this stage tomorrow. (:fingerscrossed:)

With that same set up I'll finish cut the ends and top then set up the angle plate, do the front edge and drill out the hole.

Michael

Steamwhisperer
13th Mar 2016, 06:20 AM
Excellent work Michael
Nothing like using your machine to the absolute maximum available.
Normally after scribing lines they were prick punched so that there was no fear of losing the lines throughout the process and then machine until half the punched marks remained.
In my kit I have umpteen sets of Moore and Wright flat arm dividers yet it wasn't until I paid an absolute fortune for a set of Starrett round arm dividers that I could get any accuracy. They are brilliant.
Loving this thread.

Phil

Michael G
13th Mar 2016, 07:03 AM
I did think about punching the line but given the broadness of the line I got (two or three passes = deep line? no. In this case two or three passes = wide line) thought that would only add to the confusion. I've seen the round versions and have been told that they are better (I have flat dividers/ calipers) but being an amateur it's fair to say I need all the help I can get so may have to look for some.

Michael

Mike4
13th Mar 2016, 11:24 AM
You dont know a member close by with a HBM?
The inside of the curve would be a simple task on a borer, or a decent horizontal mill.
Following with interest.
Michael

PDW
14th Mar 2016, 04:03 PM
You dont know a member close by with a HBM?
The inside of the curve would be a simple task on a borer, or a decent horizontal mill.
Following with interest.
Michael

He *has* a pretty good horizontal mill but - as you say - this is really a dead easy job for a HBM. It'd take longer to set it up than it would to bore it.

Incidentally, IIRC you were asking about tooling to hold 30 taper (or was it 40 taper) tooling in your Kearns S type. I have such a tool if you're interested in details.

PDW

Michael G
14th Mar 2016, 05:02 PM
Thanks Peter - Yes, I'd like to think I have a pretty good mill. I didn't do this using the horizontal spindle as I would have had to do some weird thing with mounting (limited travel).
The nearest person I know with HBM is in fact Peter, but I don't know how much good it would do. The 'hole' is roughly 125mm finished size and 200mm long. Regardless of whether I used the mill or a HBM deflection/ chatter would still be an issue. The Wohlhaupter is a pretty solid boring head, so no complaints there.

Anyway, Public Holiday here today so a further fix for the cast iron tragics out there...

I finally finished the bore off. It took 5 spring cuts to get a decent finish and stable size. Might have been quicker boring between centres on the lathe but an interesting experience. I then swung the R/T through 90 degrees, dropped down half a cutter diameter and recut along the top edge.
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Then 90 degrees to clean up the first end and 180 to clean up the second. I almost came unstuck here as (as you can see in the photo) the vertical head clashed with the table when getting right down the bottom. A larger diameter cutter and I was safe - except from the chips of CI that the cutter spat everywhere.
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I did it that way as it was the best method I could think of to get the ends and top square to the bore.
Next onto the sine table to get the front edge right. Included angle is 110 degrees and I wanted it to be radial so after getting it parallel and on angle, I found the low point with the DI and marked it. Then it was just a matter of cutting to that edge. The table was then dropped down to flat and I did another pass to get an edge that should be parallel to the bore. I've learnt that straight edges parallel or at right angles to surfaces are very handy for set up so try to include them wherever possible against future need.
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The progress so far -
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Weight is down to 6.8kg. Next will be to turn it around on the sine plate and using the mill in horizontal mode, bore out the screw cavity. I also want to thin down the base a little and put in some mounting bolt holes. Getting the screw bore right could be tricky because the axis of the bores ideally has to be square and the right distance apart - although I guess I could make up a M33.83x2 screw thread if necessary...

Michael

Mike4
17th Mar 2016, 09:57 PM
PDW ,
I gave up trying find one on the web and made one .

The tool holder for the facing head takes 32mm or 11/4" dia tools so I just turned a piece of 50mm to 32mm and left about 80 mm at the 50mm size .
This was then bored and finished to take my 30 taper tooling , I did stuff up with the drive tabs , made them too deep and had to cut about 3mmoff each to let all of my 30 taper holders to be used .

I have had to make three short draw bars as the collection has 13mm 1/2 inch unc and ww threads.

I also have added some extra set screws to the tool holder to make it act like a four jaw chuck , I have managed to set each holder that I have used to less than 1 thou runout .

Michael

PDW
18th Mar 2016, 09:20 AM
PDW ,
I gave up trying find one on the web and made one .


Best way really, there was never going to be a factory source for those adaptors. I only found mine by accident when I was going through the cabinet of tooling I got with the HBM.



The tool holder for the facing head takes 32mm or 11/4" dia tools so I just turned a piece of 50mm to 32mm and left about 80 mm at the 50mm size .


That's interesting, all my tool holders take 40mm shank tooling.



This was then bored and finished to take my 30 taper tooling , I did stuff up with the drive tabs , made them too deep and had to cut about 3mmoff each to let all of my 30 taper holders to be used .

I have had to make three short draw bars as the collection has 13mm 1/2 inch unc and ww threads.

I also have added some extra set screws to the tool holder to make it act like a four jaw chuck , I have managed to set each holder that I have used to less than 1 thou runout .

Michael

I got a ground setting bar with mine, it goes in the tool holder, but it's pretty hard to dial out any runout if the runout is out of the plane of travel for the facing head. It's not much of an issue when facing, one tip takes a slightly bigger cut, but using a small end mill or similar (drilling) is a bit more of an issue.

My adaptor is for 40 taper tooling and is about the maximum that cold be fitted. It uses a short bolt from the rear to retain the tool shank. Shop made and pretty well made IMO.

Don't talk to me about threads, I have a mix of 5/8-11, M16 and bloody M20 buttress threads (Deckel) on my tool holders. I think I'll standardise on M16 though.

Might post a pic or 2 over in my Kearns thread.

PDW

Michael G
19th Mar 2016, 08:23 PM
Just about finished up the easy part...
The last bit on the base to be done (for now) is the hole for the worm drive. Set up was relatively straight forward - line up sine table square to the spindle (I assume the spindle is square to the table travel, so...) then line up so the trough is also square to travel. If you ever have to something like this it is far easier doing it before jacking up the table.
Finding the centre of the boss with the Taster is easy although when doing the vertical direction I had to watch for parting flash/ clean up. The exact centre is not important but I needed to know the distance between the centre line of the hole and the bottom surface of the trough. To do this I had hoped I could just pick up on the test bar with the probe and read it off the DRO. No such luck as I did not have the travel. Plan 'B' - I got out a small sine bar and set that up at the same angle so that the top surface of that and the spindle would be parallel. Using the test bar and a rule I adjusted the position of the sine bar so that the bottom edge of the test bar and the bottom edge of the rule sitting on the sine bar were level. I could then just remove the rule and measure the height of the sine bar.
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That measurement was needed to start thinking about the screw and it's sizing/ placement. After facing the boss the hole itself was easy - it was drilled out to around 22mm and then bored out to 29mm as a starting point. I need to get a longer boring bar sorted for the Kaiser. The Wohlhaupter would fit but the head is large enough that it would interfere.

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As for the screw, the best fitting screw will have an OD of 32.6mm with (because of that pesky Pi) a pitch of 4.47mm. Out with the worm cutting change gears for the lathe again it seems. I never did get around to making the full set so perhaps here is an opportunity in disguise.:doh:

The next bit will be the semi-circular part that sits in the trough. I was originally thinking of machining that from solid in steel but I'm now wondering whether a casting may be an easier way to go. Hmm.

Michael

jhovel
20th Mar 2016, 03:36 AM
Unbelievable, Michael. I never get tired of trying to follow your thinking for these set-ups....
As I said before: always educational!
Thank you.

KBs PensNmore
4th Apr 2016, 12:59 AM
So how's this project going Michael? Still deciding on the next stage?
Kryn

Michael G
4th Apr 2016, 07:39 AM
I need to start on the semi-circular bit. The plan was to machine from solid but I'm tossing up about making up another pattern and casting. The project is not dead yet...

Incidentally, one sold on Ebay the other day. Universal Angle Table in VIC | eBay (http://www.ebay.com.au/itm/231891855836?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

Michael

Michael G
10th Apr 2016, 07:07 PM
One thing that I have to do is bore out the place for the adjusting screw. I managed to part do that by drilling and boring but ran out of reach on my boring head. The boring head of choice for small work is a piccolo and they came with all sorts of accessories to hold tips for the various types of boring that may be attempted. One was an extension piece. I have a contact at Kaiser but because these boring heads have not been made for some time, stocks are limited to what they have. Prices are still high though.
Anyway, a good opportunity to have a go at making one. The only information was a catalogue picture, so pretty much make it up as you go along. The second item on the page is an offset extension. I have a plan to make that too but given the issues with this one will leave that for a while.
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The first steps were simple and so I haven't got pictures but a piece of bar stock was machined down so that there was a solid disc (diameter 63mm) with two smaller diameter (19mm) sections either side - sort of like a barbell in reverse. This was then parted off so I had two oversized engine valves. I chopped the sides of the disc off with the bandsaw and then using the mill, neatened up the flats and used the DRO to drill the two mounting holes. I made two for two reason; firstly it seemed simpler in turns of making the blanks but secondly I wasn't sure that I would not stuff one up, so the second was insurance. It's a practice more common than you may think - set up takes a lot of time, so the extra time to make a second part is negligible and partly insures against Murphy type issues.
Our story starts from here....
First thing to do was clear out the centre section because looking at the part and where it goes I could not see how it would be constrained so that when in use it would not move - the obvious solution to me was that the attaching holes had a boss around them that located in the boring head, so the securing screws were only in tension.
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The next step was lining up the part in the lathe so that the material around the hole could be turned away. I held the part in a collet chuck, held that in a 4 jaw and then using a gauge pin, centred on that. If you ever have the opportunity to buy a set of gauge pins, think seriously about it. They are good for sizing holes, but also for establishing set ups like this.
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If it were a single boss it would be easy, but because of the second boss, machining was done with a small boring bar with the lathe running backwards. That's what was happening in the first photo below. The second photo shows a pair of bosses, with the second almost complete. The first boss was the easy bit but the second had to be the right centre distance from it as well as be the right diameter. Having measured the diameter of the first boss and knowing the centre distance, there were frequent stops to measure the second and then calculate the outside to outside dimension to compare with measured - sort of like using toolmaker's buttons (and the method that inspired this)
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After getting that part done, the rest was relatively easy - the holes on the top side had to be counterbored for M5 SHCS. I have a set of drill bits (0.5mm increments) with flat tips I use just for this purpose. Another thing if you have a spare set (or old set) that is worth thinking about if you do this sort of thing (drill a starter hole with a normal drill of the same size and then swap to the flat tipped one for finishing). Milling cutters can be used of course but that requires setting up in the mill. The top was cross drilled and tapped for a grubscrew to hold tips.
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The next thing to do is the clamping rod (sits inside the boring head and acts as a nut for the M5 SHCS - relatively straight forward but relying very much on the hole positions for these parts.

One of the problems that I had was the relative flexibility of the set up to hold the part while making the bosses. I noticed I could lose position easily because of the slight impact every time the boring bar came around. Although this method worked, constant monitoring was required and this was with an offset of just a little under 19mm. The other type of extension would require an offset of around 38mm, so a different approach will be needed - perhaps a jig on a faceplate to give more support to the part.

Michael

Michael G
17th Apr 2016, 08:14 PM
I started cutting out the blanks for the second type of extension today but after doing that realised that my preferred roughing cutter had a damaged hole so that an insert could not be secured. It was one of those 'gunna' jobs that's been hanging around for a bit. The screws themselves are M2.5 and can break easily. Some time ago I'd broken one and while drilling it out damaged the thread such that the screw had very little holding power. I'd tried welding it up before but that did not seem to work, so on to plan B (Plan C was to shorten the cutter back to the next row of inserts but I did not really want to do that).
First thing to do was drill out the damaged thread. I'm using a toolmaker's microscope to find the centre. Normally the ring light is not necessary as the mill lights are bright enough but because the hole is at the bottom of a pocket, it is in use this time. The blue plastic square sitting on the eyepiece tube is a spacer which I take off and use so that I can wind in around the right amount and know I will be close. (I have no desire to keep winding past the focal point and crash the microscope into the job).

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Having drilled the hole out I then found my smallest tapered reamer and tapered the hole (large side away from insert). The theory was that I could then put in a tapered plug and avoid a cylindrical one pulling out. The plug was made from a 1/8" bright steel nail - about the only small diameter piece of steel I could find on short notice. It only needed to be around 5mm long but was easier to make longer. An imperial taper is 1:48, so on the business end of the plug the diameter had to be reduced by 0.1mm. The second photo shows the plug in place, a small amount of Loctite 222 was used along with a 16oz hammer.
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Clanger time! The original plan was to machine that plug on the lathe and because everything would be concentric, slide it straight into the hole and I would be done. As you can see from the photo with the microscope, the cutter is hanging in free space. During the drilling, it swung down so that the hole was no longer square to the insert face but I did not spot this until after I'd drilled the hole. Instead I put in the plug and then using an insert, spotted through. I then lined up the spot using the microscope and drilled through with a 2.05mm drill (this time supporting the cutter). Finally using the same positioning, I tapped the M2.5 hole, using the mill spindle to keep it vertical. The second photo shows the back with a cutter in place.
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In terms of things to note for similar jobs in the future,

Better support for the work piece (a vice alone is dicey holding a cylindrical piece that has some overhang). Erring on the side of caution in that respect is a good thing.
The tapered plug idea seems to have worked well. Time will tell if the steel in the nail is good enough to hold. Even if I find I have to redo with something stronger, removing the current plug and replacing should not be difficult.
A toolmaker's microscope is really handy for this sort of work. The blue spacer played its part, preventing mishap.
To avoid breakages in future I probably need to run this cutter a lot faster (that is, less load per tooth)


The finished cutter back in it's holder
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Hopefully I can successfully use it next weekend...

Michael

Anorak Bob
9th Aug 2016, 11:29 AM
One thing that I have to do is bore out the place for the adjusting screw. I managed to part do that by drilling and boring but ran out of reach on my boring head. The boring head of choice for small work is a piccolo and they came with all sorts of accessories to hold tips for the various types of boring that may be attempted. One was an extension piece. I have a contact at Kaiser but because these boring heads have not been made for some time, stocks are limited to what they have. Prices are still high though.
Anyway, a good opportunity to have a go at making one. The only information was a catalogue picture, so pretty much make it up as you go along. The second item on the page is an offset extension. I have a plan to make that too but given the issues with this one will leave that for a while..........

Michael

No idea how I missed all of this! :doh:

A few questions Michael... What steel have you used? Why M5 and not M6? And how about an increase in the thickness of the the mount to say 12mm to allow for a pair of pressed in 10mm locating spigots or bosses as an alternative to your integral bosses? ( Me being lazy ). And finally, from a strength point of view, how important is the cove or radius at the base of the 19mm bar?

Bob.

Michael G
9th Aug 2016, 12:26 PM
You know Bob, I was wondering why you had not been peppering me with questions about this one as it concerns Kaisers.


What steel have you used?
It was an offcut of something I had that was marked hy-case. I can't find any information on it, but I would guess it to be a mid or high carbon steel with a few bits that allow it to take a case readily. The force that the tip will apply is relatively small so nothing exotic is called for. I did not plan on case hardening it - it was just what I had.


Why M5 and not M6?
I scaled from the catalogue page that you had sent me some time ago and that seemed to be the size. The bigger the screws, the less meat there is in the nut as that is limited to diameter 10 by the boring head construction


How about an increase in the thickness of the the mount to say 12mm to allow for a pair of pressed in 10mm locating spigots or bosses as an alternative to your integral bosses? (Me being lazy).
:doh:(Me being stupid) Didn't think of doing it that way. It would work although they would need to be stepped to avoid pulling out. Can't see Kaiser doing it that way, and my only guide to sizes was that illustration


And finally, from a strength point of view, how important is the cove or radius at the base of the 19mm bar?
Probably not that important, but again, the catalogue page had it radiused so who am I to question Kaiser? A sharp corner would have been a stress raiser which I suspect was avoided out of good practice if nothing else. It would be really good to see the drawings for some of these parts to see what they actually are.


I'm still working on the offset version and as per my standard practice with more unusual things, I'm making two. If both get through the machining process I'll send the spare one through to totally consume your Z.

Michael

Anorak Bob
11th Aug 2016, 10:25 AM
With your handiwork as inspiration Michael, I commenced work on a similar toolholder though it may well turn out to be a petite version to suit the stumpy 13.

I found a 63.5mm diameter 4140 bar end and started work. Stalled the Hercus a few times resulting in the shearing off of three of the expensive Kennametal inserts I had been using. A change to a Kyocera ceramic insert proved more successful. The ceramic produces a great finish but one easily marred if the ribbon like swarf clumps up on the tool. Whilst I never usually wear gloves while operating my lathes, turning jobs like this one using 4140, have me resorting to slipping on a pair of leather gloves to save my dainty fingers. One horsepower limits the depth of cut to about 1mm at 1200 rpm with a pretty gentle manual feed rate. The slowest power feed is too fast.

I have to work out a way of holding the flanged bar while boring the offset mounting holes. Maybe turn the mill's head on its side?

Maybe another thread with photos because this is one is about an angle plate and what an angle plate it is !!

BT

Michael G
11th Aug 2016, 03:58 PM
Oh bugger.
I've just sent off a care package to you with the left over extensions in it. The finish on the offset version is not quite what I would prefer but although not mirror like it is functional. I used a different method to do the lugs too - machine away the excess material and then set up the boring head so that it is cutting in rather than cutting on the outside. Never done it before so was not sure how it would work out.

Yes. The angle plate - need to get back to that:B

Michael

Anorak Bob
12th Aug 2016, 10:03 AM
Yet another care package! You spoil me Michael. :)

No more insert breakages yesterday but a struggle to maintain a consistent finish. I will pause until your handiwork arrives. No point doubling up unnecessarily. How did you machine the offset extension? Hopefully not one huge chuck of steel turned to swarf. And hopefully you photographed the work in progress.

Bob.

Michael G
12th Aug 2016, 11:09 PM
... And hopefully you photographed the work in progress.

Err...no.
however, due to the wonders of analog technology, it can be recreated!
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Slice a piece from the middle of a piece of round bar - keep the offcuts as they can be (and have been) used for other things
Mark out two nested piece. Drill a couple of holes and use the bandsaw to cut them out
Mount in a 4 jaw
'Round up' the long section. I used the 1/4" round insert cutter I'd spoken about earlier. http://metalworkforums.com/f65/t199380-reflection-useful-tool One advantage of this cutter is that as well as automatically putting in the root radius, it would do both surfaces. While there drill a hole down the middle (diameter 5mm).
Flip the part around and clean up the back. Using a plunging tool to clear out some space and then use a boring bar to machine the first boss.
Mount the part in the mill vice. Find the position of the first hole and measure out the centre distance to drill the second hole. Use an end mill to remove the excess material. Using a boring head with the cutter inwards, machine the second boss.


363780 (there was one picture taken, so it did happen)


After that it's tidying up - putting in the cross drilled tapped hole to hold the cutters, boring or drilling the counter bores for the SHCS and so on.
Once the fastener holes were present I made up a dummy mounting block and put that in the 4 jaw so I could get the ends of the short section of the L concentric with the centre of the part (and hence the boring head slide it would be mounted on)

Michael

Anorak Bob
13th Aug 2016, 12:57 PM
Fantastic!

I imagine you have a vertical bandsaw? I couldn't hold a stumpy section of round bar in my 300 dollar horizontal 4x6 so turning would have been my only option. Any way you look at it making just one of these bars is a hell of a lot of work. Making two, wow!!

I have often eyed off round insert tool holders, I might have to spring for one. Could be the ideal coving tool for nasty steel.

Thank you Michael.

Bob

KBs PensNmore
13th Aug 2016, 02:59 PM
I couldn't hold a stumpy section of round bar in my 300 dollar horizontal 4x6 Bob

Hi Bob, I've a 6X4 same as Michael and I'd guess most of the members on here, WHY can't you hold a stumpy section of round bar????
With some simple attachments made, a piece 12mm long could be held.
On the fixed jaw a plate is bolted/clamped so that its edge just clear of the blade, on the swivelling jaw, a plate is bolted to it that extends to the blade and extends the other side so that a nut can be welded to it and still line up with the fixed jaw. A piece of all thread is then screwed through to adjust the moving jaw to be parallel or slightly wider with the fixed jaw.
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The bracket that is hanging down is what I made for cutting 45 degree pieces, saves adjusting the back stop all the time, particularly when doing 90 and 45 degree cuts.
Another that I've started to do is a plate 150 mm wide X 200 mm long X 10-12 mm, that has threaded holes on a grid pattern. Pieces are clamped using the holes and clamp bars from the mill or scraps.
There is a 6X4 bandsaw users group on yahoo, that has a lot of ideas. yahoo.com/neo/groups/4x6bandsaw/conversations/topics

Kryn

krisfarm
13th Aug 2016, 03:23 PM
Hi Bob,
Kryn's modification to your saw works. I have only cut one piece of 75mm diameter bar length ways on my horizontal bandsaw as I needed a slice out of the centre like Michael needed I tack welded a piece of 100mm*12mm section bar around 200 long to the edge of the bar, this enabled me to make the two length way cuts pretty easily.
Bob

Michael G
13th Aug 2016, 03:30 PM
My bandsaw can be used in vertical mode but I prefer not to as it is not really designed for doing thick stuff that way. The two short cuts in the slice were pretty standard (except the cut was stopped once it got to the hole). The long cut between was trickier. The front jaw comes close to the blade so I think I probably put it vertically against the jaw and used a bar (a bit like RC's cutting aid in application) to hold it there.
Other options for cutting short items that I use are these (shown before). The first uses a V block and I would have used this sort of setup for the first cut of the slice in the middle of the round; I probably would have switched to the second set up so that the next cut was roughly parallel.
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Michael

Steamwhisperer
13th Aug 2016, 10:27 PM
While we are on the subject of cutting odd bits, Dad wanted me to make some clamps to hold a table top together.
The pieces wwere 35mm diameter and 16 mm long and had to be cut smack in half.
I used the bandsaw in the vertical mode and made a cutting jig.
Slow by hand but quicker than what I thought.

Phil
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KBs PensNmore
13th Aug 2016, 10:38 PM
Nice work, probably took longer to work out how to hold it and make the tooling than to do the job.
Kryn

jackaroo
17th Aug 2016, 11:42 AM
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Michael

I was wondering what will happen when the cut goes to near the end. Will the force from the vice make the gap smaller and eventually it will jam the blade in the gap? Or is there a way to stop that from happening?

Michael G
17th Aug 2016, 06:30 PM
Once I get around around half way down I put a bit of sheet material in the cut so that it does not close up.

Michael