Toolpost Collet Holder

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HotGuns
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Toolpost Collet Holder

Post by HotGuns » Sun May 04, 2008 7:47 pm

Awhile back I ordered a couple of 5C collet holders for the Lodge and Shipley lathes that I use at work. These things work great, are quick to set up and will do anything you need them to do.

They are expensive though, over 300 bucks a piece for the toolposts that we are using.

They work so well, I decided to make one for my lathe at the house.
Its made of scrap,in this case some 4"x4" 4150 squares that we used for a special project.

For things like small boring bars, threading boring bars and things that need to be held tightly, it works much better than securing a bar in the normal fashion with a few setscrews.

The piece is tightend with a wrench that I made just for the knurled nut,which pulls the collet against a taper much the same as it would if it was in the headstock.

and since a picture is worth a thousand words...here is a couple of pics..

Image

Image

time consuming to make...but well worth the effort. I see no reason that it couldnt be adapted to just about any lathe...if your tool post is big enough to handle it anyways.
Bob

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SteveM
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Post by SteveM » Sun May 04, 2008 8:08 pm

That's slick.

Too big for my Atlas, but no reason I can't make one in 3AT.

My dad has the BXA MT holder and used a drill chuck and a gun drill under carriage feed to drill the bore in a model cannon. Gets you a lot more travel than the tailstock ram.

Steve

HotGuns
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Post by HotGuns » Sun May 04, 2008 8:15 pm

Really, it ought to work for about any collet style. As long as you have a way to pull it up and tighten it...but that could be accomplished by the nut on the end pulling against the threads.
Bob

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SteveM
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Post by SteveM » Sun May 04, 2008 8:46 pm

HotGuns wrote:As long as you have a way to pull it up and tighten it...but that could be accomplished by the nut on the end pulling against the threads.
.645x26tpi - good excuse to learn internal threading

Steve

HotGuns
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Post by HotGuns » Sun May 04, 2008 8:51 pm

That is small. Might be easier to make a tap.
Bob

Jose Rivera
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Holder

Post by Jose Rivera » Sun May 04, 2008 10:20 pm

Nifty!!

What can I say?
There are no problems, only solutions.
--------------
Retired journeyman machinist and 3D CAD mechanical designer - hobbyist - grandpa

Mike Walsh
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Post by Mike Walsh » Mon May 05, 2008 12:26 am

This is quite interesting! I have to ask, though.. Would this put any type of pressure onto your collets that may damage it?

Granted, I understand that it's being pulled into the taper, which would "secure" it... Plus, if you think about it, you're putting just about the same type of pressure onto the collet just as you would if you were to be machining with a turning tool in an collet...

Just thought I'd ask... you know what they say, stupidest question is the one not asked.

:)

Mike

Harold_V
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Post by Harold_V » Mon May 05, 2008 4:06 am

Mike Walsh wrote:This is quite interesting! I have to ask, though.. Would this put any type of pressure onto your collets that may damage it?
As long as you match diameters to collet size, there's no good reason to expect any damage.

When collets are used, if the diameter of the item to be held exceeds the collet size, the collet is sprung open, causing only the very rear of the collet to grip the item in question.

Likewise, when the diameter is less than the collet size, the collet grips only by the outer end. In both cases, the part is subject to damage from the collet, and you risk damaging the collet. Grip recommended sizes (it's good to try to stay within ± .001" from nominal) and there should be no difference between using the collet to hold a boring bar, or using the collet to hold a piece being machined.

Harold

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Re: Toolpost Collet Holder

Post by Harold_V » Mon May 05, 2008 4:09 am

HotGuns wrote:and since a picture is worth a thousand words...here is a couple of pics..
Way cool, HotGuns. A work of art, really!

Harold

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JimGlass
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Post by JimGlass » Mon May 05, 2008 4:03 pm

Nice!!

How did you make the 10 degree taper for the collet?

Jim
Tool & Die Maker/Electrician, Retired 2007

So much to learn and so little time.

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HotGuns
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Post by HotGuns » Mon May 05, 2008 8:21 pm

How did you make the 10 degree taper for the collet?
I chucked it up in a 4 jaw chuck and drilled it. Then I bored it. The taper was cut using the compound. It wasn't a big deal really.

You cant see it, but there is a setscrew in there to keep the collet from rotating..much the same as using a hex or a square collet block. When you tighten the back nut, it pulls the collet into the block and on the taper, which tightens it considerably.

Since you have a grip that go around the whole boring bar, rather than a couple of spot if you were using setscrews to hold it, its a more rigid setup...and more rigid means less chatter.
Bob

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