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stiven
12-08-2004, 03:46 PM
Can anyone help me out? Ihave been machining for a long time but have never heard of collet blocks (8 sided,7 sided, 6 sided)for machining splines or whatever. How do they work?

[This message has been edited by stiven (edited 12-08-2004).]

jwaggs
12-08-2004, 03:58 PM
Enco has "collet blocks". If this is what you are talking about. They have four and six sided blocks that will accept 5C collets. The blocks may then be clamped to a table or clamped in a chuck to machine the stock held in the collets. Aren't that expensive either.

Spin Doctor
12-08-2004, 04:28 PM
This something that would be a good tooling project for some one. The 4 & 6 sided ones are dirt cheap these days and are useful as all get out. The production of odd sided and 8 sided blocks really don't require that much more than a sine bar for setting the angles. The accuracy that you make them to can vary, it all depends on the care in machining andif one has a surface grinder available. For instance an 8 sided can be produced with a set of vee blocks and a 45D triangle. Once the bore is finished to size place a piece of stock (1.250") through the hole and rest the stock in the v-blocks. Take a cut off one side. Now rotate the block so the machined surface is against the solid angle and take another cut. Index again. Because you are indexing three flats after 8 operations you will have generated the basic geomeetry. The method is the same for 5,7,,9,10 or what ever sided blocks you need to make. If one is making an engine project that requires fixturing to produce multiple angles on parts that can not be achieved with a normal index unit (a Hardinge 24 pin or a spin index) this is a good way to do it. This shows what the basic mill set-up would be although it is not in the machine
http://img.photobucket.com/albums/v19/markandannie/collet%20blocks/MVC-002S.jpg
This shows the basic grinding set-up that I used
http://img.photobucket.com/albums/v19/markandannie/collet%20blocks/MVC-006S.jpg
This shows the realtionship between the solid angle and it's being three flats off from the side being machined.
http://img.photobucket.com/albums/v19/markandannie/collet%20blocks/MVC-005S.jpg
This is a set I did this year for the use in building 5,7 or 9 cylinder radials. I also did the 8 beacause I was doing the rest any way.
http://img.photobucket.com/albums/v19/markandannie/collet%20blocks/MVC-004S.jpg

jfsmith
12-09-2004, 12:10 PM
I have three collet blocks, I use them with my 5C colets and this allows me to hold round things and move them in a reasonably precise fashion.

They aren't that expensive, and then spend the money on good collets and a collet wrench.

Jerry

stiven
12-09-2004, 03:53 PM
Spin, It looks like you use a set screw to hold your part in the Multisided block, would that be correct? And then rotate your block in the vise or whatever to machine the sides of your part...Or some multisided blocks are made with collets inside that you tighten up to hold your part...I think I get it now. http://bbs.homeshopmachinist.net//cool.gif

Spin Doctor
12-09-2004, 04:11 PM
The set screw acts as the guide pin that goes in the slot of the collet. The lock nut is made from a #7 bearing lock nut just as an expeidency. I've got a couple more specials I'm going to rough out in the next week or so. Maybe I should write it up and submit it to Niel.

Thrud
12-09-2004, 05:25 PM
Spin Doctor:
Very nicely done - you should submit it. I would install a hardened pin in the blocks and suggest that you make a cam type nut for it - because you can. Get rid of that ugly lock nut on those spiffy tools or you will be spanked severly! (that, or be fed meatloaf) http://bbs.homeshopmachinist.net//biggrin.gif

Spin Doctor
12-09-2004, 05:44 PM
Dave I do have the cam style lock from the Enco ones I purchased many moons ago. Another item to use with these is of course collet stops both internal and face stops. Of course with the internals the cam operated has to go. Besides I've made up special lock nut sockets for doing spindle work anyways

And if I'm gonna eat meatloaf I'll eat the wife's meatloaf with mashers and green beans

[This message has been edited by Spin Doctor (edited 12-09-2004).]

Smokedaddy
12-09-2004, 09:20 PM
Spin Doctor,

I'd sure like it if you would put together a chronological, step-by-step, for beginners, article. I’ve never used 5C collets, so I’m not exactly sure what they are or how different they are from ER’s. Not sure what Dave is talking about either, meaning a cam type nut for it? Any additional pictures with a cam type nut and would be appreciated.

Seasons Greetings,
-SD:

[This message has been edited by Smokedaddy (edited 12-09-2004).]

nheng
12-09-2004, 09:54 PM
I have a Walter German indexing head on which 5C collets are closed via a nut on the front face which pushes the collet in. This is another closing option which works well but pulling from the back is still the better way to go (IMHO) because it puts the collet in tension and causes additional rigidity.

Den

Spin Doctor
12-10-2004, 05:36 PM
I'm working on it Smokedaddy, I'm working on it. But as the Home Shop is still a dream I have to do them at work on lunch. Be a while