How To Get Accurate Milling- Vn16 Bad Collets-what To Do?

Wells Index is a machine manufacturer, in fact thet are the only game in town if you want a new US made milling machine. I have no idea if they grind collets.

I am tempted to see if I can get my 16s taper reground to 30. Might be an option to regrind the spindle to something more common.

Jason
 
Interesting that the collets would gall before the shank on the tooling.
Usually the collets are harder. Or at least that's been my understanding.
I've not heard of flex hones. Found them easily enough with a quick google search.
Will they take of material indiscriminately or target the burrs?
Wonder if you could find someone with a ID cylindrical grinder?
I've no recollection of what I got for runout last spring. Likely I should have taken notes.
Does your Drawbar seat well?

I found these links interesting:
http://blog.cnccookbook.com/2013/10/23/checking-measuring-toolholder-runout-cnc-milling-machine/
http://www.mmsonline.com/articles/the-real-cost-of-runout

Daryl
MN
 
get a fine toothed round file and very carefully get those burrs down. If you can blue the ID of the collets you can keep a careful eye on your filing to make sure you're not hitting anything but the burr.
 
mattthemuppet said:
get a fine toothed round file and very carefully get those burrs down. If you can blue the ID of the collets you can keep a careful eye on your filing to make sure you're not hitting anything but the burr.
Click to expand...

I've file'd off burs on morse collets with good results. I generally use a half round needle file. I have used small rolled up pieces of 1000 grit wet dry paper for very small burs too.

If all your collets are beyond repair you could get an ER collet chuck as a cheep option. A full set of collets and a holder should be quite reasonable in price.

Stuart
 
Matt and Stuart,
Thanks for this -- will try to rehab these collets--
--Bob V
 
Bob,

It may be a King's English thing, but in the US, "collets" are usually split and tighten on the tool (or whatever) via the action of some sort of taper. It's true that Van Norman lists the Morse taper adapter as "Taper Collets", but they are really a form of arbor. (And they call the same bit of tooling for a NMTB 40 spindle a "Taper Adapter".)

It strikes me as unlikely that all of your collets are bad. There's probably something going on with the spindle, as others have suggested. Find something like your MT2 taper adapter that's in good condition, check it on the surface plate using V-blocks and a sensitive indicator. Insert it in the spindle in various clockings and see if the runout stays with the spindle or follows the tooling.

McMaster-Carr sells expandable laps that could be used to lap the ID of a collet to take care of a burr. Go easy though, because you can easily cause more problems than you fix with one. But if your collets really are bad, you don't have much to loose by trying. However, make sure that you've eliminated your spindle as the source of runout first.

By the way, you'll probably find that your drill chuck setup, above, costs you too much vertical space to be useful. I have seen Van Norman 'C' to Jacobs taper arbors, but they are rare as hen's teeth.
 
Thanks to everyone for the help-
I finally got in my shop today, and did some testing (Dykim HiSpot) on the spindle, collets and arbors. I used the only really accurate indicator I have that reads .0002". I'm convinced there's a problem with the spindle-- the runout is ALWAYS directly away from the side of the spindle with the key--that is to say, the "high side" of the runout is right at the keyway. It's only .0015" , but this is only about 1/2 inch below the collet--much more further out. I think what has happened is that over the years, (this is a 1948 machine) the collets and arbors were intermittently drawn into the spindle with the drawbar without lining up the key with the keyway. When I got the machine the key was damaged, but there were two spare keys--so I simply replaced the spindle key. This may be hard to understand without pictures-- but I forgot to take them. Anyways, I think whenever tool holders (collets or arbors) have been drawn into the spindle without lining up the key-- the key has exerted tremendous force on the key side of the spindle mouth, and has literally bell-mouthed the spindle on the keyway side.! I can see this with the bluing. I can even measure this runout measuring the outside of the spindle-- again it indicates the spindle is bent out right at the keyway.

--So, I can't see fixing this myself-- but I'm open to suggestions--
--Maybe it's time to call Wells-Index and spend the $200 and get the spindle reground to a more common taper-- would fix two problems: spindle damage, and damaged hard to replace collets--

Looking forward to hearing from you guys--
Thanks in advance for any responses-
Bob
 
Bob V said:
Thanks to everyone for the help-
I finally got in my shop today, and did some testing (Dykim HiSpot) on the spindle, collets and arbors. I used the only really accurate indicator I have that reads .0002". I'm convinced there's a problem with the spindle-- the runout is ALWAYS directly away from the side of the spindle with the key--that is to say, the "high side" of the runout is right at the keyway. It's only .0015" , but this is only about 1/2 inch below the collet--much more further out. I think what has happened is that over the years, (this is a 1948 machine) the collets and arbors were intermittently drawn into the spindle with the drawbar without lining up the key with the keyway. When I got the machine the key was damaged, but there were two spare keys--so I simply replaced the spindle key. This may be hard to understand without pictures-- but I forgot to take them. Anyways, I think whenever tool holders (collets or arbors) have been drawn into the spindle without lining up the key-- the key has exerted tremendous force on the key side of the spindle mouth, and has literally bell-mouthed the spindle on the keyway side.! I can see this with the bluing. I can even measure this runout measuring the outside of the spindle-- again it indicates the spindle is bent out right at the keyway.

--So, I can't see fixing this myself-- but I'm open to suggestions--
--Maybe it's time to call Wells-Index and spend the $200 and get the spindle reground to a more common taper-- would fix two problems: spindle damage, and damaged hard to replace collets--

Looking forward to hearing from you guys--
Thanks in advance for any responses-
Bob
Click to expand...
Bob,
Wells-Index works on spindles, not collets (that I know of).

If the high spot in the runout tests was opposite the key, that would send me directly to the key area looking for problems. Listen carefully to what Daryl (Uglydog) is saying, too.
Edit: Check that $200 price, too. That is an old man's memory from many years ago and might well be wrong, probably in the upward direction if it is like other prices I remember...
 
I cannot see a flex hone doing any good for your issues, only tearing up the surfaces. The abrasive balls are at the end of springy wires and follow the surfaces and scratch them. They are not intended to level the surfaces. Fine for seating piston rings or breaking up the glaze in a brake cylinder, but a flex hone would be a very bad idea in your spindle or collets, in my opinion.
 
Thanks for all the help--

FYI,
On Friday, I called Wells-index and they agreed to look at my spindle. Initially they declined to service it, but I persisted and they agreed to try.
I have sent the spindle head, along with the drawbar and several collets and taper arbors to Wellls-Index. Hopefully they can regrind it. Their ability to proceed depends on whether they can set it up (I think they should be able to do this), and whether they can drive the spindle. They drive the spindle while grinding the taper.
Thanks for all the advice that led to this-- I hope they can do it!
Best regards,
Bob
 
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