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DA collets

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Cornish Jack10/07/2019 11:23:12
914 forum posts
120 photos

I have some DA collets which were bought secondhand. Checking against the published dimensions I appear to have a partial saet of DA200s. The checked dimensions are CLOSE TO the published for that range, but not exact. What degree of tolerance should one expect for the D1, D2 and L values ? (I'm assuming the holding value will be to spec)

Any advice appreciated

rgds

Bill

Neil Wyatt10/07/2019 18:09:02
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16277 forum posts
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74 articles

Hi Bill,

Is it possible they have been over stressed?

Googling the beasties it appears they have a tendency to crack at the nose if used to hold milling cutters, presumably because they aren't designed to collapse for their full length like ER collets. So be aware of this!

Neil

Cornish Jack10/07/2019 18:32:20
914 forum posts
120 photos

Thank you Neil - I appreciate what you say about possible fragility but my query is actually about identification. The D1 etc. values shown on the 'net are Imperial to 3 decimal places and the items I have differ by 2 or 3 third place values. They are not marked as to type so I'm wondering if I actually have DA200s or some other type? The closeness of approximation is such as to generate a doubt but I can't find acceptable tolerances for collets and holders. Hope that makes sense - (got to be a first time for everything!!sad)

rgds

Bill

JasonB10/07/2019 18:52:32
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15773 forum posts
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Depends on what published sizes you are looking at. a quick google for DA200 gives the larger dia as 0.531", 0.532" and 13.7mm ( 0.539" ) and lengths of 1.188", 0.19" and 30mm (1.811" )

Emgee10/07/2019 18:56:12
1149 forum posts
206 photos

Hi Bill

This may help, if your collets are close to these dimensions should be OK, also remember there is a max tightening torque.

 

sowadacolletdimensions.jpg

Edited By Emgee on 10/07/2019 18:59:28

Cornish Jack10/07/2019 21:19:31
914 forum posts
120 photos

Thank you Jason and Emgee - " if your collets are close to these dimensions should be OK, " ,,, that's what I was after; Yet another raid on the piggy bank!

rgds

Bill

Phil P10/07/2019 22:03:59
486 forum posts
128 photos
Posted by Neil Wyatt on 10/07/2019 18:09:02:

Hi Bill,

Is it possible they have been over stressed?

Googling the beasties it appears they have a tendency to crack at the nose if used to hold milling cutters, presumably because they aren't designed to collapse for their full length like ER collets. So be aware of this!

Neil

These collets are actually designed to collapse over the full length, they have a double taper where they get pushed into the collet holder, and a single taper that the nut pushes against.

Probably not quite as effective gripping power as an ER but still pretty good, I have used them for years with no problems. If you make your own collet holders the two internal tapers have to be precisely located with respect to each other to ensure they share the load and collapse in a parallel manner. I have made special reamers with tapered depth stops to facilitate this.

collets 048 30-08-13.jpg

collets 050 30-08-13.jpg

It is the middle two at the bottom of the next photo, they are for DA200 and DA300 collets.

collets 054 30-08-13.jpg

I also use DA180 for work holding.

collet blocks da180.jpg

Phil

Cornish Jack11/07/2019 16:20:23
914 forum posts
120 photos

Phil - very impressive. The sort of thing I would like to do but age and incompetence rule against!. My query was a roundabout way of finding out if a sale item would be suitable for an existing collet holder.

rgds

Bill

Cornish Jack12/07/2019 23:22:59
914 forum posts
120 photos

Just to tidy this one up - the DA200 published dimensions are NOT exact. The new and old sets are interchangeable as regards holders.

rgds

Bill

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