Brian G | 10/12/2018 09:18:39 |
912 forum posts 40 photos | Hi Andy This is on my "to do" list should I be able to use my SL (I must first print a set of guards so I don't fall onto the pulleys or chuck, which I suspect would hurt) although I would probably go for ER11 as I already have the collets. Each of the stages in making an ER16 collet chuck on the Unimat SL is illustrated, and each photo has a text description. The screwcutting is done by an ingenious method that takes advantage of the headstock quill movement, which removes the need for the rare and expensive Unimat thread chaser and masters. Brian |
John Haine | 10/12/2018 10:41:47 |
5563 forum posts 322 photos | Yes, I'd forgotten that the older (pre Unimat 3) models had the ability to rotate the headstock around a vertical axis for taper turning, so one can make the collet taper without a topslide. My 3 of course doesn't have that feature. |
Andy Carlson | 10/12/2018 19:18:21 |
440 forum posts 132 photos | I really like that way of cutting a thread on the SL. It's a bit of a roundabout route and it took me a few double takes to figure out what was actually happening but you have to admire the ingenuity. At the moment I'm persevering with the backplate. The front end has had 3mm taken off the register and the fixing flange (using the Cowells) and the finish turning on the SL is now down to 0.12mm oversize. I'm taking a break now. Some runout reappeared during the finish turning. I'm pretty sure this is down to unevenness in the casting. I've now resharpened the HSS tool and tightened every Allen screw down. I think I'll also seek out a wedge to add some extra support under the nearer of the two bars. Anything to help the rigidity! |
Nicholas Farr | 10/12/2018 21:46:49 |
![]() 3988 forum posts 1799 photos | Posted by Neil Wyatt on 09/12/2018 14:11:33:
Posted by Nicholas Farr on 09/12/2018 13:46:07:I can always remember a saying on the back of a box of matches (can't remember the brand, but there were hundreds of different sayings on the back of their boxes)
England's Glory, Moreland, Gloucester? Hi Neil, yes they were the one's. They were the type that could be struck on just about anything, downside of course, they were not a safety match. Regards Nick. |
Andy Carlson | 11/12/2018 23:08:39 |
440 forum posts 132 photos | The register is now finish turned to fit the chuck again. I'm pretty sure there is no measurable (by me) runout on the backplate register now. The fit is good again but fit-wise I think I did a bit better at the first attempt. After trying all three possible orientations of the chuck I got a runout between 0.6 and 1 thou inside the chuck taper. The runout was consistently towards the same side of the chuck so I think this is coming from the chuck. With some judicious tapping before finally tightening the screws I was able to get the runout down to about 1/4 thou, with a similar reading on with the 3mm Proxxon cutter in the collet. I think I will stop messing with it now. In other news, I found at least one place (Cutwel) that offers ER16 full sized nuts in a choice of hex and pegged wrench varieties (plus they do the mini one too). They also do a 25mm A/F spanner that looks rather more sensibly proportioned for this job. I do think that I will try making an ER16 chuck for the Cowells myself (on the Cowells)... but not for a day or two. Thanks again for all of your input. Regards, Andy |
John Haine | 15/12/2018 16:34:43 |
5563 forum posts 322 photos | Following Joseph's observations I thought that a good substitute for a double-sided spanner would be a socket. I didn't have a 25mm socket in my set, and anyway since one will be tightening the collet with either a tool or material in the collet a long-series socket is needed to give it room. It seems to be near impossible to get a long series 25mm conventional socket, but I managed to locate one designed for impact driving on Amazon from KS Tools. Conveniently it has transverse holes at the drive end that with a bit of easing allowed a 25 mm tommy bar through. This allows me to tighten the nut hard without applying much or any transverse force. I also needed a way to lock the spindle - the collet end has a pair of flats which are 20 mm a/f bit only about 6 mm wide. Believe it of not buying a thin 20 mm open-end spanner seems to be near impossible, they are all about 10mm thick at the business end. Eventually I gritted my teeth, got out my trusty 8 mm TC slot drill, and reduced the a/f dimension to just under 19 mm so I can use the very nice "Williams Superslim" spanner that came with my VMB. This was a job made very easy as I could hold the spindle in a JS ER40 collet block. |
Andy Carlson | 15/12/2018 16:51:18 |
440 forum posts 132 photos | I've ordered a 25mm spanner from RDG. It hasn't arrived yet but it seems (from the picture) to be more sensibly proportioned for use with the collet nut. I still need to make a proper tommy bar to fit the holes in the chuck because (inevitably) they are a different size from my other chucks and my die holder. |
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