ER 32 collet holder run out

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ER 32 collet holder run out

This topic has 22 replies, 8 voices, and was last updated 6 October 2018 at 18:59 by Raphael Golez.

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5 October 2018 at 17:36 #374708
Raphael Golez
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@raphaelgolez
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
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5 October 2018 at 17:36 #19101
Raphael Golez
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@raphaelgolez
5 October 2018 at 17:50 #374709
Thor 🇳🇴
Participant
@thor
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
5 October 2018 at 17:53 #374712
Muzzer
Participant
@muzzer
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
5 October 2018 at 19:36 #374719
Tony Pratt 1
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@tonypratt1
If the register is doing nothing why not adjust the run out to zero?

Tony
5 October 2018 at 19:57 #374726
Raphael Golez
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@raphaelgolez
Posted by Tony Pratt 1 on 05/10/2018 19:36:44:

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?
5 October 2018 at 21:13 #374737
Michael Gilligan
Participant
@michaelgilligan61133
Posted by RAPHAEL VAL GOLEZ 1 on 05/10/2018 19:57:38:

[ … ]

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.
5 October 2018 at 21:34 #374742
Raphael Golez
Participant
@raphaelgolez
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?
5 October 2018 at 22:01 #374744
Michael Gilligan
Participant
@michaelgilligan61133
Posted by RAPHAEL VAL GOLEZ 1 on 05/10/2018 21:34:14:

… 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.
5 October 2018 at 22:11 #374748
Raphael Golez
Participant
@raphaelgolez
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?
5 October 2018 at 22:16 #374750
Muzzer
Participant
@muzzer
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
5 October 2018 at 23:10 #374759
not done it yet
Participant
@notdoneityet
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
5 October 2018 at 23:41 #374760
Raphael Golez
Participant
@raphaelgolez
Posted by Muzzer on 05/10/2018 22:16:19:

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

Murray, I tired but the link is not working when I click it.
5 October 2018 at 23:49 #374761
peak4
Participant
@peak4
Here you go Raphael,

Regards

Bill

Edited By peak4 on 05/10/2018 23:50:33
5 October 2018 at 23:53 #374762
Raphael Golez
Participant
@raphaelgolez
Posted by not done it yet on 05/10/2018 23:10:46:

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

I don't think the backplate is the issue. My S7 spindle is ok when I clock this, the register that I turned is also ok when I clock it although as I mentioned its not a tight fit as I wanted some fraction clearance to fine tune it with the DTI. I'm not sure of the PCD of the backplate though eye balling it through the bore of the collet holder seems to be ok but there is no way for me to know for sure. I will try again to gently tap the "high" spot on the clock while the 3 bolt had a gentle holding pressure and see what happens. My concern is the register might not be small enough to allow small movement but on the other hand I'm worried that if I skim to much the register will be ineffectively too small.
5 October 2018 at 23:55 #374763
IanT
Participant
@iant
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
5 October 2018 at 23:58 #374764
Raphael Golez
Participant
@raphaelgolez
Thanks Bill.
6 October 2018 at 00:05 #374765
Raphael Golez
Participant
@raphaelgolez
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
6 October 2018 at 00:05 #374766
peak4
Participant
@peak4
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
6 October 2018 at 00:10 #374767
Raphael Golez
Participant
@raphaelgolez
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?
6 October 2018 at 00:20 #374768
peak4
Participant
@peak4
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
6 October 2018 at 00:31 #374769
Raphael Golez
Participant
@raphaelgolez
Thanks Bill, I will try clock it tomorrow. I will update results after. Have fun and enjoy your new purchase, I have no luck on getting a Boxford shaper so far.

Cheers,

Raphael
6 October 2018 at 18:59 #374848
Raphael Golez
Participant
@raphaelgolez
Updates:

I managed to set it as much as my adjustments permits. Current reading on my DTI is .01 mm which is 0.393701 (in thousandth of an inch). Is this an acceptable tolerance? For what I do I can accept it but what do others think?

For future reference in which others might encounter this with this set up, this is what I did to bring it to that tolerance.

1. Register is on the loose side to allow sufficient adjustment (but not to loose).

2. I have to reduce the diameter of the supplied allen bolt head to around 8.8 mm to allow movement for adjustment as the original allen bolt head diameter does not allow this. This saved me from re-boring and counter boring the collet chuck holder as the tolerance on the original bore is critical on the periphery (to big and the side will be thin).

3. An accurate and precision collet with a tight runout will further help with accuracy

Issues encountered:

1. I think the register on the back of the collet chuck is not that accurate.

2. The backplate PCD is also not accurate with the collet chuck's PCD.

3. the allen bolt supplied had a big head diameter (The counter bore on the collet chuck is I think big enough, to big of a counter bore will run the risk of a thin walled area on the collet chuck's peripheral margins).

Perhaps its best to have a single collet system like the ER 25 which is directly screwed to the spindle of Myford lathe. However having the backplate and collet holder system allow for someone to fine tune the system to almost zero reading. Other factor that I needs further testing is how accurate the taper is and accuracy will be further enhance with a precision collets and lock nut.

Any additional thoughts will be most welcome. Hope this will help others in the future.

Cheers,

Raphael
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