View Full Version : R8 collett questions..

08-07-2011, 03:30 AM
Be gentle just learning,....

Just bought a used Jet mill/drill, and it came with a set of R8 collets.

1. Some of them have some surface rust on them,(No Pitting). What is the best way to to remove the rust and protect them from future rust?

2. Some of the collets are tight when being inserted into the quill, they will tighten down but but do not initially fit all the way int the quill by hand.
One quill does fit perfectly. The specs of the threaded end are about .15 in
difference between the good one and the tight ones.
Is there that much of a difference between import and standard U.S.A brand name?
The one collet that does fit, does not look like it is part of the same set.
Slight differences in the way it looks plus the difference in end size.


08-07-2011, 04:33 AM
Soak in vinegar to remove the rust.
Everything will loosen up with use, there is surprisingly little variation required to generate an apparent difference in fit. Get it all clean and rust free, use it a lot, and it will all reach a happy average.

08-07-2011, 05:33 AM
If you are referring to the diameter of the threaded end then I doubt the difference is 0.15"??


The specs of the threaded end are about .15 in
difference between the good one and the tight ones.


08-07-2011, 07:30 AM
Here's a diagram for R-8 with measurements.


08-07-2011, 08:16 AM
To get off the rust I'd just spin them up in a lathe between centers and use a little Scotchbrite saturated in oil on them. If you don't have a lathe you can just do it by hand. Then clean them off well and add a light coat of clean oil. Also, if you do not have a lathe, you can "buff" (like you are buffing a shoe) the diameters that will not fit with very fine emery cloth and constantly check the fit to see if it is improving. When you begin to be able to slide it into the mill check for shiny spots on the surface when you pull it back out and concentrate on those. Just keep repeating this till it goes in. These diameters are important but the most important is the taper at the front of the R8. That being said, you don't want to remove any more material from the shank than is necessary for a good fit.

As far as the difference between import and and brand name - if you plan on eventually taking your skills to a higher level always buy quality over import. If the accuracy demands of your typical project are not great you can go with the cheaper brands but personally I wouldn't advise it. You may later graduate to a Bridgeport and you will be either forced to use all the cheap junk you bought to accommodate your cheaper mill or buy the same stuff all over again for greater dependability. I bought a new 13 X 40 geared head Jet lathe and a Bridgeport clone (also a Jet) and I am very happy with the machines. I saved a lot by going import on the machines and I have no regrets so far, but I always bought the best accessories I could possibly afford to use with them in the event that I would later sell these machines to buy better ones.

08-07-2011, 08:41 AM
What DAT said.... A green ScothBrite pad from the grocery store and some kerosene or light oil is a great way remove surface rust.. FWIW I find it's worth buying the ScotchBrite brand pads over the generic store brand. They seem to hold up better and last longer.

I also agree that quality collets are worth the money. You don't need that many collets for a milling machine: 1/8, 3/16. 3/8, 1/2, 5/8, and 3/4 will satisfy virtually all requirements, so you won't go broke buying good ones. Unless you're going to use tiny carbide end mills, you can omit the 1/8 size. Hardinge collets are top quality, as are Royal, and IMO worth their higher price. They fit correctly, they are accurate, the spring temper of the collet is correct so it closes and grips well, the drawbar thread is well done...etc.

08-07-2011, 12:29 PM
When you are inserting a collet, make sure the collet and it's seat in the spindle are clean!
A little piece swarf can keep the collet from sliding in easily, and when you tighten it down it can scar the collet seat in the spindle, That's a bad thing.

08-07-2011, 03:15 PM
If the OD is to big at the threaded end they will be hard to insert. You can chuck them in a lathe and use emery cloth on it to reduce the OD so it fits.

when you chuck it up stick a piece of scrap in the collet the size of the collet. Gently emery it down till it fits smoothly in the spindle.

08-07-2011, 08:44 PM
When you insert the collet, could you be hitting a very worn down drive pin?

try rotating the collet ( just the collet - not the spindle) as soon as you feel a little resistance until you find an easy spot where the collet goes right up.

08-07-2011, 08:56 PM
I have bought 3 or 4 sets of R8 collets. Surprisingly only 1 collet had much runout,and it was pretty bad.

If you use oil in sprucing up your collets,BE SURE to get every bit of it out of the collet. If you don't,it is so easy for an end mill to get sucked right out of the collet,and into your vise,or into your mill's table. Mt work partner had that happen,and cut a ring out of the table on our milling machine.

08-07-2011, 09:03 PM
A good piece of advice Geo.

08-08-2011, 12:23 AM
If you are referring to the diameter of the threaded end then I doubt the difference is 0.15"??

You are correct I made an error in typing.
The specs for the collet call for a diamter between .9495 in. and .9490 in.
The collet giving me trouble measured .9560 in. so it is closer to .007 over.
Dont know how I typed .15in.

08-08-2011, 12:32 AM
Thanks everyone for the replies.

I have used a Scotchbrite(Used brand name) pad with a little oil to clean the rust off, a little elbow grease and boom good as new..

This is the collet set the guy gave me with the mill when I purchased it
so, I am not really out any money by buying a cheap set.

I WILL however in the future when I look at tools be sure to go with a more
superior than import so I will not have to buy the same thing twice.


08-08-2011, 12:58 AM
cheap collets wont always fit right. i got a cheap set with my cheap chinese mill the 1/4" collet looked new! the draw bar threads were cut about 3/16" short. i had to make a washer just to use it.. and i had to use it because id bought about 35 1/4" shank resharpened EMs off e-bay.