https://youtu.be/gaUFyG4fyfk?si=wMNwXCMDmU2oEm8D
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Thanks Alans Home Workshop! We've added your Square Stock Holding Method to our Lathes category,
as well as to your builder page: Alans Home Workshop's Homemade Tools. Your receipt:
<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="https://www.homemadetools.net/homemade-square-stock-holding-method"> <img src="/uploads/272468/homemade-square-stock-holding-method.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="https://www.homemadetools.net/homemade-square-stock-holding-method">Square Stock Holding Method</a> <span> by <a href="https://www.homemadetools.net/builder/Alans+Home+Workshop">Alans Home Workshop</a></span> </div> <div class="tags">tags: <a href='https://www.homemadetools.net/tag/chuck'>chuck</a>, <a href='https://www.homemadetools.net/tag/holding'>holding</a>, <a href='https://www.homemadetools.net/tag/collet'>collet</a> </div> </div> </div> </div>
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Given the proper thickness shim, I think I can center square stock in a 3 jaw chuck. I just tried it in my shop. I haven’t derived the equation relating stock size to shim thickness but I’m sure Marv can do it quicker. With one jaw vertical, shim goes on it. Other two jaws press on the stock at the top corners.
My chuck jaws have a taper on the flank so that complicates the math.
The ECCENT program on my website* had a program for computing the shim size needed to make eccentrics in a 3jaw. I consider using the 3jaw for jobs that really should be done on a 4jaw an unnecessarily dangerous operation. Even offsetting for an eccentric can be done more safely without a shim using a technique described in the text file that accompanies the program.Quote:
Originally Posted by rgsparber
A much safer way to handle square work in the 3jaw is to make some cylindrical "collets" as I described here...
https://www.homemadetools.net/forum/...802#post114541
If you finally break down and mount the 4jaw, you face the problem of centering the stock - a task the "collets" do automatically; this task can be made easier if you add my "flapper" to your DI used for centering...
https://www.homemadetools.net/forum/...7183#post36582
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* The generous soul who hosted my website died on his 50th birthday so the site is no more. However, a fully usable version of it is available on some sort of "way back" machine here...
https://web.archive.org/web/20230526.../mklotz/#intro
There's perhaps a simpler variant of the square "collets" to which I referred in the previous post.
Take a piece of cylindrical stock and bore it out to be a close sliding fit on your square stock. Slice it end to end with a small end mill so that the 3jaw can clamp down and close it down on the square stock.
If I were doing this (which I wouldn't be), I would arrange for the diameter of the cylindrical stock to be about 10% greater than the diagonal of the square. This so it's flexible enough to close down and grab the square without requiring undue pressure from the 3jaw chuck.
As an interesting obversation worth noting, my regular every day chuck is a 200mm self centering 4 jaw. This type of chuck will hold hexagonal cross section work (eg a nut) which will automatically be self centred. Extraordinary but true, try it for yourself.
I think the maths for this might be quite complicatedQuote:
Originally Posted by rgsparber
Attachment 48448
That's a great idea.Quote:
Originally Posted by mklotz
Thanks, Alan, I'm glad you like it.Quote:
Originally Posted by Alans Home Workshop
Yes, the edges of polygonal stock are seldom exactly the same distance from the center so better results if you center on the faces rather than the edges. But rotating from face to face puts the sensing stalk of the DI at risk unless you use something like my flapper.
Accounting for the shape of the jaw tips would make it complex indeed !Quote:
Originally Posted by Alans Home Workshop
If the jaw tips were flat, I think it might be easier. Since the 3jaw is self-centering, the bottom jaw must be at the same distance from the center of the square as the two top jaws are.
Let:
S = length of the side of the square stock
Then S / √2 is the distance of the top jaws from the center of the block and the shim needs to be S / √2 - S/2 = S ( √2 / 2 - 1/2) = S (√2 - 1) / 2 = 0.2071 S
Oh, that it were that simple. :-)
Regardless, shimming isn't nearly as safe as a collet arrangement along the lines of what I described.
That was a Very Well done video, I especially liked your desktop camera setup, SIMPLE Works best!
philip, from the Great Pacific NorthWET, Oregon Division, USA
Thanks Philip. I had tried using this setup in some of my earlier videos, but synchronising the recordings from the two cameras was a bit finicky. However, I discovered that my video editor (Kdenlive) allows setting the audio from one recording to be the "master" and using that to synchronise with the other recording. This works really well and made things much easier.Quote:
Originally Posted by philippacificnw
Hold the square part in a collet over the corners. Just miss the slits, easier with a 5C but still possible with an ER. Failing that, a split bush over the corners in a collet or chuck.
