ER 32 collet holder run out

Good day gents, I was trying to adjust the ER 32 collet holder chuck on my lathe. This is from RDG with a spindle back plate. I did the register a fraction smaller and not tight to allow minute adjustment. The run out is around 10 thou which is really bad, I got it to around 6 thou at best. Once the bolts are tighten and settled in I don't think the register is doing much. Is it a mistake to make it slightly smaller? I think this is the culprit or simply say my error on my part. Can this be rectified or I need to replace it? I don't think there is any other way around this. Inputs are all appreciated.

Cheers,

Raph

Hi Raphael,

6 thou is worse than I managed on my homemade ER-32 chuck for my small lathe, I ended up with around 1 thou, but my chuck mounts directly on the lathe spindle nose.
If the runout is caused by the register not being tight enough, then if the back plate is thick enough you may be able to turn a new register and hopefully get less runout. If it is the chuck you might contact RDG for a replacement.

Thor

Have a look at Threadexpress's video channel where he discusses chucks and backplates. The "adjustable backplate" method is just what you are describing and if it's good enough for Cluff (he's a Kiwi it's going to be good enough for the likes of anyone on this forum. There are 3 parts to this video and part 2 seems to have some particularly relevant stuff around 11 minutes in.

If anything it sounds possible your register needs to be further turned back to provide enough adjustment.

Obviously you need to be certain the backplate is clean, free of nicks etc and properly / squarely seated before you start looking to adjust the chuck.

Tell us how you get on.

Murray

If the register is doing nothing why not adjust the run out to zero?

Tony

Hi Tony, Thats what I did but the 3 allen bolts that hold it down to the backplate had very minimal movement. I have difficulty adjusting the collet chuck. Loosening it to much is also difficult. I tried to tighten it enough for some slight movement (which is very small due to the register not being too loose) and adjust the chuck but no luck at all. Once I tighten the 3 bolts it seems that it just aligns itself with the backplate. The counter sunk and the bore of the bolt on the chuck is enough for the bolt head and thread to just fit. Not enough movement. If I did a tight register this will likely automatically align the chuck and the bolt will just follow it instead. Is there any chance that there is a fix?

.

Raphael,

If you are using countersunk screws, I think that problem ^^^ is almost inevitable.

Counterbore the holes instead, and make sure that the through-holes and counterbores all have have enough clearance [hopefully, not very much].

Replace the screws with good capheads, and flat washers if there is room.

MichaelG.

Thanks Michael. Got your point. What I mean instead is a counter bore instead of counter sunk. Enlarging the counter bore and through-holes just a fraction to allow adjustment of the chuck to be as close to zero might do the trick. I can understand this principle like in the four jaw. How about the 3 bolt set up as in this case? Do I reference each of the 3 bolt?

.

Possibly the best [simplest] way to adjust would be to just 'nip-up' all three bolts and then use a pusher to persuade a mandrel to run true. ... Difficult to describe, but easy to do !!

This is essentially the way that lens elements are centered, or that we use a ''sticky pin'

... Then fully tighten the screws and check the result.

[repeat ad nauseam !]

MichaelG.

Michael, when you say use a pusher to adjust to run true you mean to use a lever into the collet holder taper and apply a gentle push?

Rater than talk about it, just watch the video #2 and you can see exactly how to do it. That guy is a very experienced toolmaker and his runout is pretty darned good....

Murray

I can’t really imagine a concentricity problem with a backplate turned in situ. If it has that much run-out on a concentric backplate it is a useless piece of junk and RDG should be ashamed to market it.

Edited By not done it yet on 05/10/2018 23:11:24

Murray, I tired but the link is not working when I click it.

Here you go Raphael,

Edited By peak4 on 05/10/2018 23:50:33

Raphael - provided the ER taper itself is properly formed (e.g. not distorted) - you should be able to get the chuck to run dead true (e.g. within your means to measure it). You should only need a small clearance on the register and whilst I used cap screws - they are not countersunk (just washered). They are at the back of the chuck so shouldn't be dangerous standing proud provided they clear the lathe itself when running. You want to allow some movement, so be sure to also drill generous clearance holes (e.g. 6.5mm for 6mm caps). One thing that might cause you problems, is if you haven't got the backplate holes in quite the right place with respect to the chuck (or vice versa - they are slightly out on the chuck itself) - as this will also tend to restrict the degree of movement/adjustment possible - or perhaps bias it.

Otherwise, this is not unlike centring a four-jaw. Grip a short piece of silver steel (larger the diameter the better) and clock directly on to it. Then just tap the chuck true. I use a fairly small plastic faced hammer - and you don't need to be brutal. The end of a small lump of hardwood would also do it. Turn the chuck and tap down on the high spots indicated. Provided the chuck has enough freedom to do so - it should be settable to have zero run-out (or at least as near to that as your patience and metrology will allow). Once you get where you want to be - just nip up the screws (each one a wee bit at a time) - then check again. Shouldn't move if you are careful.

Regards,

IanT

Thanks Bill.

Got it Ian. Thanks. I might be a bit impatience and like you said be on the gentle side in tapping. I will try it again tomorrow and report back progress and if no luck then the chuck might be a good paper weight.

Edited By RAPHAEL VAL GOLEZ 1 on 06/10/2018 00:06:05

Edited By RAPHAEL VAL GOLEZ 1 on 06/10/2018 00:06:25

I picked up a "New" second hand one a while ago at an autojumble for a very decent price.

When I fitted it to the Myford spindle, the runout, with a ground bar in a collet, was huge.

On examination, the register of the backplate was nigh on perfect, but clearly hadn't been machined since it was made. Seem the previous owner has tried to machine the collet chuck part to fit the backplate, rather than the other way round.

The concentric rear centre hole was about 10 thou off centre, and they had even skimmed the rear surface too.

I ended up holding a piece of ground round bar in a 4 jaw and clocking it in, then mounted the collet chuck, in reverse one the bar, via a suitable collet in the chuck.

I touched up the bore, and skimmed the rear, after which I was able to use the above method to get a reasonable runout. Far from perfect, but a sight better than when I got it home.

Bill

Did you just skimmed the register after Bill? Did you do a tight fit on it or a bit undersize to allow to tap it?

Undersize register on the backplate to allow some movement, I left the backplate exactly as it left the factory, as it clocked up accurately with a 10ths dial gauge.

The hole in the rear of the collet holding part of the combination was by now well oversize due to the actions of the previous owner, and I'm not convinced that I got the new bore spot on concentric at the first attempt.

Something about the whole setup is a bit off, as I'm getting slightly different runouts on different sized collets.
Eventually I'll have a go at re-making it.

Currently on with trying to re-commission a Boxford shaper I've just bought off ebay.

Bill