Collet chuck not running true

[Hauk]

I have a collet chuck that I feel is not entirely up to snuff.

First, I checked that the main spindle is running true, the dial barely moves when clocking it, around 0,005 mm.

But when clocking the bore of the collet chuck I get a runout of around 0,1 mm (0,004"). Isn't this a bit high for a collet chuck of supposedly good quality?

Checking the bore of the spindle:

checking the bore of the collet chuck spindle:

Max. runout as indicated:

 

[Tin Falcon]

Mark current position.
turn it 120 degrees test again. repeat if needed. when you find the best position mark the chuck and plate permanently engrave stamp so it will be mounted the same way each time. if that does not give good enough readings install a set true adjustor. that will allow you to slightly adjust the chuck on center.
Tin

 

[Spurry]

Depending how true the register is in the first picture, and how it fits in the rear of the chuck, you could always machine a couple of thou off the diameter of the register to give you a bit of tweaking room. Only do this if Tin's suggestion does not give you a decent reading.

Pete

 

[Tin Falcon]

Also remember clean clean clean. it only takes a piece of metal crud .002 inches cube to throw you off that much.

 

[picclock]

I'm guessing this is a lathe, so you may be better off rethinking and going for a 4 jaw chuck. I just bought one from Warco for very small work. I'm sure someone hear will correct me, but I think the max specified ISO runout for an ER25(??) collet is still about a thou, although a lot of manufacturers produce (especially budget imported) chucks that have greater tolerances than that.

The other 'fix' you could try to implement is to turn down the registration ring on the chuck backplate and then drill and tap 4 grub screws on the edge to set the correct centre position.

First though it may be worth checking the accuracy of the location ring on the spindle as this is what sets the chuck alignment, not the spindle Morse taper which you are indicating off.

Hope this helps

Best regards

picclock

 

[Blogwitch]

Hauk,

This is a common problem with these types of collet chucks (and the cheaper 5c ones as well), it is all to do with the fact that they are not machined on your machine, but a general machine in the factory of the manufacturer, so they can almost be guaranteed to have runout in them. They look pretty, but that is about it.

If what Tin says to do doesn't work, then really it is better to skim out the taper yourself, it is then guaranteed to be spot on. It isn't such a daunting task as people suspect.
I have actually done a couple of your type for other people by using soft jaws on my lathe and truing up the nose tapers, and they, when remounted to the lathes they came from had less than 0.001" runout.

Of the four 5C collet chucks that I have fitted to my machines over the years, all have had to be skimmed up, the last one was 0.008" out, and that was AFTER turning it to the best position. On that one (the one on my lathe now) I had to skim the back up first before attempting to do the nose.

John

 

[Tin Falcon]

boring insitu will certainly guarantee accuracy . but try the simple stuff first clean and check for best position. in any case mark the position that works so when you take it off and replace it it will be in the best possible location and you do not have to keep making it right.
All good advise. a four jaw will give lots of versatility but I do like the accuracy and speed of collets. since you already have the collet chuck you may as well learn how to make it right for your lathe.
Tin

 

[mike os]

bit ot

any suggestions where to get an er32 on a MT5? or anyone care to make me one?

 

[Tin Falcon]

do not know if comercialy available you could get one of these and a 5 -3 adaptor.
http://littlemachineshop.com/products/product_view.php?ProductID=2228&category=
If you have a 5MT head stock why not get a MT5 to 5-c collet adapter and draw bar. Should be readily available on the used market.
Tin

 

[mike os]

cost & flexibility Tin... 5c... one size fits one size & relatively ££££ ER one size fits a small range, readily available & fairly cheap, also only need one collet set for mill (when it happens) Appreciate that it is potentially "less accurate" but you have to live within your limitations...


would prefer to avoid stacking adapters etc, every one is another error...

I could probably make myself.... its just the thought of 2 tapers on one piece & the opportunities for it to go wrong....usually right at the end.

 

[dalem9]

I beleave I have a 5t3 adapter If you can give me the specks I will measure them to see if they will work . Dale

 

[Blogwitch]

Mike,

I have made both, but not together.

I made MT5 to Myford nose, so that I could hold Myford chucks and fittings on both lathe and RT, and then Myford fitting to ER32, again for swapping between lathe and mill. Not too bad making either of them.

The difficult bit was making a decent drawbar system for the lathe, as I surely wouldn't want to hold anything in the lathe spindle taper without one.

Making the MT5 taper, and a bit further down the page, making the drawbar

http://madmodder.net/index.php?topic=1993.0

Making the ER nose

http://madmodder.net/index.php?topic=2249.msg23587#msg23587

Hope this gives an easy solution to your problem.

John

 

[mike os]

thanks thats great

what material?... ie grade of steel? ( not got any 2" so will have to buy & may as well buy something suitable as not)

 

[Blogwitch]

Mike,

Both parts were made from an hydraulic cylinder ram, hence the use of the toolpost grinder to clean up the machining marks, it was a bit heavy to cut to a good finish.
I am not a stickler about what I use, for what we do in our shops, as long as it is some sort of steel and I can cut it, I will use it. It will see me out, then it isn't my problem.

There will be no real heavy forces on it, so if having to buy material, I would use something like EN8 or even EN1A if you want to get a super easy finish on it.


Hope this helps


John

 

[lensman57]

Hi,
I have had 5 different ER25 collet chucks adapter plates from ARC EURO trade for my little Taig lathe and none were anywhere near as accurate as they should have been. Two were turned on the lathe itself and were slightly better but not near enough. As was Suggested in the other posts if nothing else works turn down the register by about 0.05 mm , slightly loosen the retaining nuts on the chuck enough to hold the chuck just firmly and then set up the indicator on the on the spindle nose. Adjust the chuck by tapping it very gently with a soft hammer as you rotate it and it will center, eventually. In my case the chuck screws on the Taig spindle so once you are happy with the chuck you can tighten the nuts on the chuck and use it as required. Also make sure everything is squeaky clean. I also have a sieg X1 which I no longer use due to this adjustment being a pain, no matter if it is a 3 jaw self centering or a collet chuck, there is just not enough hours of the day to spend truing out the chucks.

Regards,
A.G

 

[Hauk]

I have frequented quite a few newsgroups, bulletin boards and forums since I first logged on to the Internet in 1991, but this forum is on my shortlist for the most useful one ever!

Hope to be able to return the favours.

Regsrds, Haavard H

 

[Hauk]

Just a little update to let you know that at least my trouble with the collett chuck has been solved.
Turned out that the chuck did not mate exactly with the spindle due to a too shallow recess on the backside of the chuck.

I got a replacement with a deeper recess, and now I am able to chuck parts in my collets with less than 0,02 mm (0,0008") runout.

So, all I have to do now is to get the crosslide back in order!

Regards, Haavard H.