CNC Spring Collet by Feiuruhf,MT3-ER32 M12 9pcs Spring Collet 3-20mm CNC Lathe Milling Tool Spring Collet Set Chuck Collet for CNC Engraving Machine & Milling Lathe Tool

For less than $50 these are great for holding stock in lathe. Runout can be from .004" to .008". But these are still so much nicer to use than the bulky 3 jaw chuck that came with my Grizzly G4000.You have to understand the effects of this Runout when removing and replacing the same piece of work in the the collet. But it is the same as using a 3 jaw chuck. You will not get repeatability if you remove the workpiece and put it back in again. If you can get around that limitation then these will hold your work much more firmly and you can get much closer to the collet than you could with the 3 jaw chuck. There is no worry about the cutting tool colliding with the chuck jaws.This set is not suitable for holding a cutting tool on a mill. The runout is more than the depth of cut. This will cause your cutter to break. If you really need an ER-32 collet to hold a milling bit then you are going to have to pay for the proper precision. Try at least $180 at Little Machine shop and they do not even publish specification for their sets.I settled for an ER-20 MT3 collet set for my mill. A good precision set costs about $60. Tiny and precision is not expensive. Large and precise is going to be very expensive. The MT-32 collet is very large, it will hold up to a 3/4 inch bit.If you need to hold a cutter over 1/2 inch then a better choice is to use a full taper collet which would be much more rigid anyway.Here are the numbers from my G4000 9" X 19" lathe.My spindle has a runout of about .0005" and the ER32 Chuck has another .001".These collets have anywhere from .004" to .008" runout .The .004 was attained by aligning all the high and low spots on the spindle, collet chuck and collet.There are very few reviews for collets in general where the reviewer actually measures the runout. I ended up returning several sets before settling with these ER-32 and the ER-20 set.The attached photo is the ER-32 collet chuck holding a 20mm straight shank ER-20 collet chuck. Using the 20mm shank was one of ways I measured runout. The indicator is just showing a random value at this time.I originally left a one star review when I first received these. The seller recently contacted me in order to try to make things right but I declined the offer because I had been using these on my lathe and am very satisfied with them. I had reviewed them as if I had paid hundreds of Dollars for them. Since these have a German brand name, my expectations were extremely high and I did buy them for use on my mill. For $47 these are a great buy to use on my lathe.You may need to purchase some M12-1.75 Threaded Rod, nuts and washers to make a draw bar for this.

The chuck seemed to be of decent quality and the runout was less than 0.001" but the collets or the nut were incorrectly sized such that the collets were not self extracting. Everytime I needed to remove my material I had to remove the nut and use a wood block to knock the collet out if the chuck. Had the first one replaced but the second behaved exactly the same.Returned both and ordered from another manufacturer.

3-20mm is false advertising. It has every other size. 3-4 - yes 4-5 - no, 5-6 - yes, 6-7 - no, etc.If you can live with that, this is a decent set.

Needs thread pitch specifications for shaft, fits good though, collets seem to work okay.