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14th Nov 2017, 11:07 PM #196Golden Member
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Simon, good idea. I had a square up against the column ways looking for 15 thou or so gaps but no joy. I reckon I'll give your idea go.
Baron, it wouldn't matter so much for grinding a top surface, but for grinding the side of something it
may well do. I am not an expert either by any stretch. My concern at the moment is how far it is from connolly's recommendations. Going forward that will be my guide for getting the old girl back into shape.
Edit: and thanks for the comment re the thread baron. Appreciated
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15th Nov 2017, 06:11 AM #197Philomath in training
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Remember though that the numbers in Connolly (which are pretty much the numbers in Schlesinger btw) are the recommendations on what an acceptable standard for a reconditioned machine should be. There are plenty of machines out there that exceed those limits and still produce satisfactory work.
If you were in the precision grinding business I would encourage you to chase those limits because it makes your job easier. However, for the average task that you are likely to do it may matter at the end of the day.
Michael
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15th Nov 2017, 06:31 PM #198Golden Member
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Thanks Michael,
Yep agree. Though, this is my first real go at understanding and measuring a machine's alignment so this is as much a learning exercise for me as anything else. If it were (say) 0.001" I'd not give it a second thought - waaay good enough!. With such a large variation I guess I want to understand whether it is my naivety or technique or whatever. I am a noob and a bit of a nong so I try not to stuff up if I can.
Which I do a fair bit anyways.
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19th Nov 2017, 06:58 PM #199Golden Member
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Proof and puddings
Hi all, the next action-lacked installment on progress on old 'Mrs Brown'.
I posted over on PM in the scraping and inspection section to see if I could gather some advice on my apparent misalignment. I roped in a big fish and Richard King himself offered some advice and some tests. Similar tests can be found in Scheslinger p74 (section 25 - "Testing Surface Grinder with Vertically Adjustable Horizontal Grinding Wheel Spindle") but the key difference with RK's advice is not using the t-slots as a reference.
I did post some results over on PM, but I can go into more detail here as I don't have to suffer the "max 5 pics per post" limitation that forum has.
After a solid burr-filing of everything I re-checked my previous head measurements - yep - spindle still at an angle to the reference surface and bearings - though a little less than my first measurements.
I remounted the head block back onto the grinder - it fits very well with no slop as far as I can tell and moves freely up and down. It sure felt great to see it there again.
IMAG2016.jpg
I mounted the boring caps and inserted the boring bar to use as a test 'spindle' for the alignment tests.
IMAG2052.jpg
Note that none of my equipment could be classed as amazingly high-precision. Like I have no idea if my angle plate is really square etc etc - but I am after indicative measurements at this point, not for scraping etc so it is all good enough for that.
Test 1: does the spindle run parallel with carriage movement in the horizontal plane:
IMAG2021.jpg
It leans in the direction I thought it might by about 0.001" in 4" - but not tooo bad actually.
Test 2: Does the spindle turn on an axis that is perpendicular to the table movement. This is a 'swing around' test. Here is the set up:
IMAG2029.jpg
The angle plate front face was set parallel with the table movement (indicated by running the table back and forth and tapping the angle plate until it was correct. The plate was clamped down lightly).
Then zeroing (well .. almost zeroing) on the left side then swinging it over to the right we look at the difference. In this case, almost nothing. So pretty good actually.
(I couldn't figure a way to mount my 0.01mm indicator so the starrett 196 0.001" had to do)
IMAG2030.jpgIMAG2028.jpg
Test 3: Does the spindle turn on an axis that is perpendicular to the table surface. Same type of swing around test vertically showed the spindle pointing downwards by about 0.007" The error in the vertical plane when setting up the angle place in this position was only about 0.001" so the droop is actually the head or the spindle pointing down. Fixable.
IMAG2033.jpg
Test 4: Are the table and carriage movement are perpendicular to each other. I set up my best (only!) square that would fit and indicated in the base to run parallel with the table and then mic'd the long edge to measure error with carriage movement. Almost zero. So we're good there.
IMAG2039.jpg
So not too bad actually. Richard King's advice was to bore the bearings as I have suggested then scrape the head in to align the spindle.
So despite a really odd alignment on the head itself, when it place it seems to be okay. I can only surmise that means the column ways are not perpendicular to the table. Who cares I guess!
All that has given me greater confidence to bore the bearings using the setup I've shown and then deal with stuff from there.
All that does not mean stuff is perfect. Without even measuring I can see the bed ways (for the carriage) are worn in the middle. This means that at the outer reaches of each end of carriage movement the carriage moves a fair bit. I am guessing this is because two worn areas hit each other and cause some movement. Not sure yet.
And, as an aside, with head mounted again for the first time since all that sorry pile of rust arrived here, I thought I'd test fit the belt that jhovel donated (thanks again Joe!).
IMAG2049.jpgIMAG2046.jpgIMAG2047.jpg
Thanks all,
Greg.
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19th Nov 2017, 07:27 PM #200Most Valued Member
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Thanks for the "how I did it", and the pics, Greg. Only way some of us can learn this stuff, by seeing how others do it.
KrynTo grow old is mandatory, growing up is optional.
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19th Nov 2017, 08:00 PM #201Most Valued Member
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Nice work. Glad it all worked out. Just goes to show, sometimes the alignment of individual components are not important its the overall alignment when they are all put together.
Cheers
Simon
Sent from my SM-G900I using TapatalkGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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20th Nov 2017, 08:00 AM #202Golden Member
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Kryn, thanks. Most of us are in that same boat!
Simon, thanks also - yes, it seems that is the case. It makes the Connolly procedure for scraping/aligning an SG a bit incorrect for this machine. Nevermind.
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20th Nov 2017, 01:50 PM #203Most Valued Member
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WRT Connolly, don't forget his publication is for machine rebuilding not machine manufacture. When you are a manufacturer, you can build and fit a machine together however you like and individual components need not necessarily be aligned only the finished products of all the components put together. An example would be a lathe headstock and it's matching bed. I doubt that the base of a headstock really needs to be parallel to the spindle axis, but when it is attached to the bed, the spindle needs to be aligned to the bed. I suspect the reason Connolly sets out such an alignment procedure with the various components is because you are rebuilding an already worm machine. It's much easier in the long term to align each component individually rather than rely on a single alignment after the components are already fitted. Machine datums and alignments of axes may not always be obvious on a worn machine so better to ensure each component is in alignment.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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20th Nov 2017, 05:04 PM #204
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20th Nov 2017, 05:41 PM #205Golden Member
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Joe, thanks. slowly, but getting there. It's been a year since you dropped those parts over. Phew eh. Hey, any joy in bugging your mate for a viewing of how the friction feed works on his BS2?
Simon, thanks. And this machine supports what you say. I do get the reasons why Connolly goes about it like he does. It makes sense. Though, his choice of datum to begin a resto is the front column ways "as they'll have very little wear" Hah! He hasn't seen mine!
At this point I am not actually looking to do a big scraping job on it - as little as I need to actually. None is okay. First aim is just to get it together and see how it performs. If it doesn't do so well then I'll have to plan a resto regime for it. And you can bet I'll be bugging people here about it.
Greg.
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20th Nov 2017, 06:20 PM #206Most Valued Member
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Hey Greg, you arte doing an awsome job. Some of the stuff you are doing to breath life back into it is impressive. I think If it was me I would still be scratching my head.....
Keep going...... I look forward to your next post.
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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7th Aug 2018, 11:05 PM #207Golden Member
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Well, after a nice summer 2017/18 break I was ready to get back into sorting this old lady out, but ... I've had a five month diversion on getting a poor neglected Bridgeport back into action:
//metalworkforums.com/f65/t2020...geport-emerges
So here we are 8 months later.
There really was no space to do both grinder and mill at the same time. Having said that I did make some small progress. Namely, line boring the bronze spindle bearings before I dismantled the BP.
The spindle head plus the end caps I made just fit on the lathe with enough room to bore one bearing at a time.
IMG_20180330_170259.jpg
There was no great way to secure it very well there, but given its considerable weight and that I was only taking a few thou at a time, I shimmed it until I could move the lathe carriage back and forth smoothly. As I had no real way of checking (in situ) of whether I had cleared the wear I just took off enough to be satisfied - likely in the range of 20-30 thou .. maybe more .. to be sure.
The boring bar is the alignment bar in previous pics - now modified. One grub screw to adjust depth, another to lock the tool in place. The tools was 1/4" round HSS cut like a shear bit and with some random hand-ground negative rake angle.
IMG_20180330_100313.jpgIMG_20180330_094328.jpgIMG_20180330_094351.jpg
Ultimately it worked well. The finish was great. All wear taken out and felt like job well done:
IMG_20180330_180911.jpgIMG_20180330_181457.jpg
But then .... uh oh ....
The bearings have a 'slices' along them. Their purpose being to be able to remove them and reduce them to take up wear. Originally made from phenolic (bakelite), these were brass so there has already been some adjustments made and likely they had been squeezed some.
Soon after cutting ... mine fell out as the bearings opened up .... I imagine springing back out and de-stressing some ...
IMG_20180401_172342.jpg
(the fourth spacer went .. erm ... somewhere ...)
So .. b*llocks and double b*llocks. I did a quicky rough survey of them yesterday and, even more unhappily, found the thicker / thinner ends have sprung differently so now the bores are also tapered and each side has sprung differently .. so they are wonky tapered. My quick survey showed that maybe, at worst, the taper was a thou or two. Research says they shipped with 0.00011" spindle clearance. Everything is relative but that ain't good enough.
So, we'll have to strike up all that effort in making caps and boring and so on to experience. It sure took a long time, but I learned quite some stuff. All good. My original plan involved lapping them in place, but a wonky taper thing means I can't quite be sure along what axis I might be lapping. Front and rear bearings have to line up.
I think I've a plan on how to make the next attempt, so getting started on that is the next thing .... actually, I'll think it some more and then explain it here for comment first.
Greg.
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26th Aug 2018, 09:07 PM #208Golden Member
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Lapping the front bronze bearing
Okay, the plan is basically this:
* Fix the 'warp' caused by the stress relief after machining.
* Lap the bronze bearings, get 'em in and if they're not in alignment, use the front bearing as the 'master' and do whatever needs doing to get the rear bearing into alignment with it. Bore-in-place - whatever.
* How to tell if they're in alignment? Create a 'dummy' spindle lapped at each end to match the bearings. If the rear bearing is not aligned with the front - then the dummy spindle gets turned into a boring-bar and the front bearing is used as a boring guide.
'Fixing' the bearings means squeezing the bearings back up a little, getting the spacers back in. Making a new one to replace the one that went MIA. Glue the little buggers in and then keep them hose-clamped until they go back in the machine.
Lapping:
Some rough measurements show that the bores of both bearings are tapered. The rear bearing by only 0.001" but that is about 10x what we're shooting for. The front about 0.003". Ouch.
I'll lap them using some home-made 3MT tapered expanding ID laps. Why 3MT? ... coz I have a 3MT reamer.
After d*cking for hours on a worn-out-as-hell taper attachment I got something near a dodgy 3MT taper set up. I bored an aluminium sleeve and used the 3MT reamer to clean it up.
IMG_20180826_140529.jpg
Re-doing the 3MT taper the other way, I turned a 'quite dodgy 3MT' tapered arbor to mount the aluminium sleeve.
IMG_20180826_154406.jpg
And the sleeve:
IMG_20180826_154423.jpg
(the 'spin' marks are from me trying to eek some more out of the reamer and it spun some)
Using the dremel I cut a very (very) dodgy slice around the sleeve to allow it to expand as it gets nudged up the arbor and also put some small notches for the lapping slurry. The slice does one turn of the sleeve. The idea here being that you tap the sleeve up the tapered arbor to make it larger.
IMG_20180826_165614.jpg
The bearings are bronze, so a non-embedding compound has to be used. I ordered this from brownells.com.au. It got shipped from the US. Maybe 600 grit is a little too coarse, but it'll have to do.
IMG_20180826_165926.jpg
I skimmed the sleeve to be about 0.001" smaller than the small end of the bearing bore taper. Some lapping compound on and this is the idea:
IMG_20180826_170245.jpg
Here it a pic of the sleeve after some use:
IMG_20180826_173255.jpg
Ideally, the sleeve would have been about 30% longer than the bearing, but practicalities meant that is not that (like I can't bore that deep). Such is life.
The result? I've only done the front bearing, but ... the result is excellent. I can't measure a bore to tenths but as far as I can tell the are within the same thou, and if I go by 'feel' of the lapper then they are very close indeed. No more 0.003" taper. So a good start to this phase of the project.
Interesting to note is that the inexactness to the 3MT tapers was not an issue. The dodgy 3MT sleeve didn't quite match the dodgy 3MT arbor but once the sleeve slice was in and it had been nudged up the arbor a little it didn't matter.
Rear bearing next.
Greg.
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6th Sep 2018, 08:53 PM #209Golden Member
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Spindle prototype #1
Rear bearing also done. I ordered some 1000 grit brownell's paste but it'll take 3 weeks to get here, so pressing on ...
I've made a new spindle and am yet to decide whether to treat it as a learning exercise or as the item - I kind of think the former. Pic shows my a practice bar sorting out the taper, the spindle #1, and at the front is the original spindle.
IMG_20180906_173617.jpg
The finish on the spindle is perhaps not 'mirror finish', I have no fine lapping paste, but successive sanding with finer wet and dry up to 2000 grit has the spindle to size - regardless of the visible scratches it is pretty smooth. The material is 4140 pre hard and I left too much material to lap/sand off so it got pretty aggressive. The spindle bearing surfaces are consistent to about 0.00005. I've really no accurate way to know if I have 0.0001 clearance between spindle and bronze bearing, but, I just kept lapping and sanding until it just went in.
I used contraptions like this to lap:
IMG_20180901_154811.jpg
.. and I used kerosene as lubricant for fitting as that is what I'll use when running it.
... and with the spindle in place. The fit is a little snug on the rear bearing but, I'll make a new pulley for the spindle fit it all up on the machine and run it (slow at first) and see how it goes.
IMG_20180906_173739.jpgIMG_20180906_173756.jpg
The proof is in the pudding so I'll really need to grind something.
Getting there ....
Greg.Last edited by StrayAlien; 7th Sep 2018 at 08:42 AM. Reason: typos
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6th Sep 2018, 11:02 PM #210.
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Impressive work on that spindle Greg.
I've made a few draw bars for the 13 from 4140 and it was a nasty job with lethal stands of razor sharp swarf. A boy's job compared to the spindle you've made. Well done.
Bob.
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