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Oldneweng
17th Dec 2015, 12:23 PM
A long time ago I discussed this subject in another thread and eventually realised that I had a drive plate for my lathe that would work as the basis for this project. Fast forward to a more recent time and I was thinking about this project again. I did some research on how to go about the machining process to work out the best way to do it. I came across a discussion about fitting the following type of item to an existing lathe (back) plate on PM.

ER40 Lathe Collet Chucks - Arc Euro Trade (http://www.arceurotrade.co.uk/Catalogue/New-Products/ER40-Lathe-Collet-Chucks)

The item that was being discussed was available (sometimes) from a web store called Tools4cheap in US for about $US80 delivered (to Canada). I just looked them up again and they are having a closing down sale. At the time I was looking I could not find any. Definitely none now.

I realised that using a commercially made chuck would provide me with more accuracy, hopefully the right materials and hardening of the taper.

I ordered the 125mm model. It arrived yesterday.

Now I am thinking about how to attach it to the drive plate. The discussion on PM was in relation to a lathe back plate, which is not quite the same as a drive plate. My drive plate has a tee slot across half the diameter and the cam lock pins extend almost all the way thru. The rear of the collet chuck has only a ring around the outer diameter. This ring (OD) sits in the camlock pin area.

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The method discussed on PM was to bore the face of the plate to an interfererence fit for the chuck back, in situ and then heating the plate and cooling the chuck before assembly. To do this with my plate I will need to mount an extra steel plate on to it for boring. I don't want to shorten the pins. I could bore inside the pin line of the drive plate for a location boss to the rear of the steel plate. Then repeat the procedure on the steel plate to fit the chuck.

When I had the previous thread going, PDW mentioned that Mick Moyle had D1-6 back plates for around $130. I did not follow this up at the time. I have just sent an email. One other thing I need to consider is that a vernier is probably not quite good enough for these interference fit measurements. I only have mics up to 4" at the moment. Maybe I should buy a set of either full mics or with interchangable anvils?

Due to the current run of hot weather and all the other work waiting for me at the moment, this is not likely to happen very quickly. I have not had any shed time for a couple of weeks. I welded up steel tubing legs and welded them to our bed rails to get rid of the bed end which was constricting in our tiny bedroom. The bed end board was pretty high and had a wide flat top. Antique Blackwood no less. It will be stored. I also welded up some "Y" droppers from rusted off old ones to complete some "temporary" fencing. I did do 1 cut with my new plasma cutter on a dropper point just to see if it worked. It worked fine but needs better guidance. That is it for shed work.

Dean

Gavin Newman
17th Dec 2015, 01:49 PM
Dean

I've done the same with one of those ER40 chucks (albeit on a D1-4 backplate so I didn't have the pin interference problems).

I didn't do the heating and cooling thing, I just turned the register until it was near the final size (by vernier) and then crept up the final size by taking "dust cuts" with a very sharp tool until the chuck was a hard-tap fit onto the register, I did make sure that the backplate cooled down before doing the final fitting cuts. There's been no sign of run-out since doing it that way and it's been in use off and on for 3 or 4 years now.

Oldneweng
17th Dec 2015, 02:24 PM
Dean

I've done the same with one of those ER40 chucks (albeit on a D1-4 backplate so I didn't have the pin interference problems).

I didn't do the heating and cooling thing, I just turned the register until it was near the final size (by vernier) and then crept up the final size by taking "dust cuts" with a very sharp tool until the chuck was a hard-tap fit onto the register, I did make sure that the backplate cooled down before doing the final fitting cuts. There's been no sign of run-out since doing it that way and it's been in use off and on for 3 or 4 years now.

How deep did you bore the register? There was mention on PM from one person who had missed the mark and had to face off and start again. Your idea of creeping up to the mark has merit, but I would like to confirm the accuracy of the caliper first. The tiniest knock on a point could spoil things. I am not determined to use heat/cool. I just want a "good" fit and that does give a bit of tolerance to play with.

Dean

Gavin Newman
17th Dec 2015, 02:28 PM
From memory I turned the spigot on the D1-4 backplate to be around 30 thou less than the depth of the recess in the chuck. Mine ended up such that it required a moderately firm tap with a dead-blow hammer to fit the chuck to the backplate but not brute force.

Michael G
17th Dec 2015, 05:25 PM
I have metric mics up to 150mm that rarely get used so a short holiday for them is possible. From memory I also have some 130 diameter bar stock somewhere so I could probably cut a thin slice off for you if you needed to make that spacer piece.

Michael

Oldneweng
17th Dec 2015, 06:53 PM
I have metric mics up to 150mm that rarely get used so a short holiday for them is possible. From memory I also have some 130 diameter bar stock somewhere so I could probably cut a thin slice off for you if you needed to make that spacer piece.

Michael

Thanks for the offer Michael. The last piece of bar stock you sent me is still unused, but it is sitting with the 4" chuck waiting. I intend to have a look around when it cools down a bit more and see what I have that is suitable. I think I have a bit of plate cut into a round that may be suitable. It depends on my memory.

My wireless weather station says it is 42 deg still. I have some doubts about the thermometer shade housing. It is only about 80mm diam. The thermometer on back verandah says 38 deg tho.

Dean

Oldneweng
19th Dec 2015, 10:50 PM
Nothing to show yet, but I have found the metal I mentioned and removed the shaft that was sticking out of the centre. I don't know what it was. The end of the shaft was square. Pretty rough tho. The piece is 145mm x 20mm. I have faced, cleaned up the edge that is sticking out of the chuck and drilled/bored the centre. Only a couple of cuts with the boring bar so far. I have to decide how big I want the centre bore. The drive plate has a bore slightly under 60mm. Maybe turn up a slug to press into this and press the steel disk onto it as well. This will prevent any movement of the disk in the future. The final bore only needs to be bigger than 25mm for max collet size. Ok, a bit bigger to suit oversize collets just in case.

Cooler weather coming so hopefully I can get a bit more shed time. I am very glad there have been no fires (touch SWMBO's head). I went to one caused by lightening a couple of weeks ago. It was burning in the same block of bluegums that reach our Eastern boundary. A bit close. Luckily the wind was blowing the other way, but I did not know what it was supposed to be doing later on. The wind was blowing pretty hard. It was an end of hot spell thunderstorm, with the temperatures lower. A bit like tonight and tomorrow actually.

Dean

Oldneweng
22nd Dec 2015, 09:30 PM
I have got a bit more done.


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The drive plate.

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The drive plate with the collet chuck in about the right axial location just to show how the 2 relate.


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Next, I turned some galv pipe down to a light press fit in the bore of the drive plate. That was the best material I could find without chopping up stuff that I felt would be better used elsewhere. The ends of the camlock pins can just be seen at the edges. The plate was faced and bored to a light press fit as well. I stoned the surface of the drive plate before pressing on the plate. Very nice fit. A bit of lanolin between the 2.

The plate will have a diameter of 145mm. The collet chuck backplate has an ID of 95mm and an OD of 125mm. I will need to drill and tap M8 x 3 to hold the plate to the drive plate for machining.

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I did up a CAD drawing to make sure that the bolts would fit etc. The inner bolt circle represents the bolts to mount the steel plate to the drive plate. I don't have any counter bore cutters so I use endmills. This means I need to turn down the bolt heads in order to keep the counterbores a reasonable size. This bolt circle is in the only possible position. There is only 17.5mm for the bolt heads to fit, in between the pipe OD and the collet chuck ID. These bolt heads have to be fully counterbored to allow facing of the plate. The counterbore diameter will be 12mm.

Once these bolts are fitted I can finish turning the OD and facing. The pipe will be faced off level. Then I need to turn a register for the collet chuck base to locate on. I guess turn all the way from the edge to the collet chuck ID, (95mm) to a suitable depth. There is a 7mm step on the inside of the collet chuck, so 6mm deep?


From memory I turned the spigot on the D1-4 backplate to be around 30 thou less than the depth of the recess in the chuck. Mine ended up such that it required a moderately firm tap with a dead-blow hammer to fit the chuck to the backplate but not brute force.

Yep! That will do it.

Another couple of points.

I don't want the bolt heads sitting proud on the collet chuck face. Just waiting to catch me or something else. Should I fully counterbore them? The rim of the collet chuck plate is 15mm wide and 18mm thick. A full counterbore of 12mm again, would need to be 8mm deep. There seems to be plenty of material.

The drive plate has a T slot on one side. Is it likely that this would cause balance problems at higher revs. I have tried the drive plate in the lathe, but only at about 500rpm. It was fine at that speed.

Dean

Michael G
23rd Dec 2015, 06:56 AM
If the T slot worried you, you could always make up a length of the right profile and secure it in the slot (a couple of roll pins or some countersunk screws?).

Michael

Oldneweng
23rd Dec 2015, 11:51 AM
If the T slot worried you, you could always make up a length of the right profile and secure it in the slot (a couple of roll pins or some countersunk screws?).

Michael

Yes. But I realised when doing the CAD drawing that I have already pressed the 2 bits together. I can seperate them, but I don't want to play around with them too much. I was thinking about a profiled piece as you said. I was wondering if anyone had any experiences that would help with the decision. I will think about it today.

Dean

Oldneweng
23rd Jan 2016, 01:12 AM
I have positioned the plate on the mill table and centered it. To avoid removing the cam pins, I sat the drive plate on 123 blocks.

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Now I will use coordinates to locate and drill the holes to secure the steel plate in position. These will be counterbored a bit below the surface to allow for machining the face. There is only a very short length of the galv tube sticking up for the DTI point. Just enough.

I have made up a profile piece to fit the Tee-slot. This will be positioned and drilled for a bolt, at the outer end while the chuck is on the mill table. The slot is hiding under the left hand clamp. I will seperate the 2 plates for cleaning up of burrs etc after the drilling and tapping is done. I can drill another bolt hole for the tee-slot piece then.

Dean

Oldneweng
23rd Jan 2016, 11:27 PM
I drilled and tapped the holes to mount the steel plate to the drive plate and one of the holes to secure the Tee-slot filler piece. I had to tap this piece in so I was happy with the result.

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Next I want to mount the chuck on the lathe so I can check for accurate fit. I moved the chuck from the position in the top photo when I drilled and tapped the hole for the Tee-slot filler, as this was too close to the end of the table. When I repositioned the chuck on the 123 blocks it had a slight rock. On checking I found a dent in the edge of it. This is a very close clearance fit so it has to be pretty good. I rubbed the dent off with a diamond stone. Hence checking for a good fit in the lathe.

At this stage I decided to finish the 2 speed motor connections before anything else.

Dean

Oldneweng
31st Jan 2016, 04:53 PM
It is finished. :2tsup:

Carrying on from the last post, rubbing the dent off with the diamond stone did not help with the fit in the lathe. I had to do a bit more and finished up going over the whole surface after removing the cam lock pins. I finally got a fit in the lathe I liked. I did not like the outer surface trueness tho. I put an indicator on the outer edge of the drive plate just to check and found quite a high area around the Tee-slot. It was as though the Tee-slot had suffered excessive force from a bottoming bolt/stud. I guess bashing the filler piece in with the sledge hammer was not a good idea after all. :D Just joking.

I skimmed the surface of the drive plate, which also just skimmed the Tee-slot filler. I then put the steel plate back on and machined it. I am not sure whether I already mentioned it, but this steel plate is certainly not MS. It turned nicely. I machined the recess on the outside allowing about 0.5mm clearance inside the collet chuck body face. Similar to Gavin's. I used the compound to cut the diameter to about 95.05mm. This was a slight mistake. The collet chuck matching bore must have had a slight taper and the compound cut a slight taper. It required tapping around the edge with a soft hammer to fit the 2 parts, but when in position the collet chuck was able to spin freely. Lift the chuck and it would move about 1.5mm and stop dead. I checked several times, but it could only be tapers causing this. A DTI showed about 0.01mm movement. Nice bearing. :D If I spun the chuck and let go, it would keep spinning for a moment or two.

I clamped the whole thing on the mill table san the cam lock pins, lined up the existing M8 threaded holes with a 6.8mm drill in the mill collet chuck and started to drill, counterbore and tap the 3 mounting holes. I stuffed up on the first one. I drilled 8mm to full depth. :~ I decided that it would be simple to use M10 cap bolts, so that fixed that problem. The steel the collet chuck was made from was very tough. The 1/2" 4 flute cutter I used to start the counterbore now needs sharpening. I finished the counterbores with my boring head. First boring bar was a brazed carbide that came with the boring head. This is now blunt as well. I am glad I bought a couple if indexable bars for it. The shorter one of these worked very well.

I turned the heads of M10 caps bolts down to suit, as there was not much room for the counterbores due to the edge of the chuck being close at hand. :rolleyes: A good cleanup and reassemble and time to mount to the lathe.

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I had to take this picture with that nick in plain view. :D More stoning. The DTI showed just over 0.02mm runout. I call that acceptable. Now to give it a try.

Dean