Choice of collet mounting

[Andy Freeman 1Participant @andyfreeman1]

[Andy Freeman 1Participant @andyfreeman1]

I want to trying milling on my Myford Super 7. I notice that there are two types of collet chuck, one that screws direct onto the spindle nose and one that is attached to a face plate.

 

Are there any advantages / disadvantages to either type?

 

The collet set and chuck from RDG looks a good one to me.

 

Thanks for your help

[NJHParticipant @njh]

Andy

 

I have the type that screws directly to the spindle nose. I don’t use it for milling – I have a milling machine- but I have a full set of ER collets for workholding and find it very good. I can see no reason why it should not be just as successful in holding a milling cutter.

 

Cheers

Norman

Edited By NJH on 10/09/2011 23:46:12

[David LittlewoodParticipant @davidlittlewood51847]

Andy,

 

There are quite a few types of collet which can be used on a Myford S7 (see articles in past MEW magazines) but the two you mention are the most common. The Myford 2MT collets which mount in the headstock taper are excellent in quality and give the lowest (i.e. best) runout, and the lowest possible overhang, hence the highest rigidity. However, there are disadvantages: (1) they only work on material or tools of the exact diameter they are made for; (2) because of the fine taper, the position of the material depends on how hard you tighten the retaining ring; (3) they are b****y expensive, and (4) since the demise of the old Myford, availability is in doubt. They sell on eBay at around the new price. You need to get the closing ring and laoding tube to be able to use them.

 

The best type of chuck-mounted collets for the use you intend are ER collets. They are designed to hold a small range of sizes, and a full set of them will hold anything (round!) within the upper and lower limits. The ER25 set covers 0.5 mm to 16 mm, which is everything you could reasonably expect to use on a S7. Provided you use the correct tightening spanner and do it up properly, they will hold milling cutters perfectly well; I have used them on my milling machine for years, and only had a cutter pull out once when I got careless with tightening. There are several varieties of chuck for these collets: a 2MT type (which *definitely* requires a drawbar); a backplate mounting type (which can, done correctly, get the best accuracy on your lathe, but you have to fit it yourself, perhaps not the job for a beginner) and the direct mounting type which screws directly to the madrel nose thread. The latter is probably the one you should go for, not quite as accurate in runout as a well-done backplate mounted one, but perfectly good for milling cuttters.

 

Hope this helps,

 

David

[JasonBModerator @jasonb]

Myford also used to make a special MT2 collet that was opened & closed by a spindle nut so no drawbar required but not as versatile as an ER. Don’t know if the new Myford will still produce them?

 

J

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