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BobWarfield
07-13-2006, 12:29 AM
Finished my Kurt Vise Stop. It was based on a design by the Fidgiting Widgitmaster over on CNCZone:

(Widgitmaster's Vise Stop) http://www.cnczone.com/forums/showthread.php?p=172743#post172743

It looked a fun project, and I had an idea I wanted to try making some split cotters on mine, so I dove in and produced this result:

http://www.thewarfields.com/img/Toys/MachineTools/MillStuff/KurtViseStop/P7123547.JPG

It was definitely good fun. The details will be obvious to the old hands. If there is any doubt, I wrote it up on my website in excruciating (sorry!) detail:

http://www.thewarfields.com/MTMillKurtViseStop.htm

I really like the split cotters. They take very little force to achieve a tight lock and are perfect in this application.

Anyway, this is a good example of how to take what should have been a simple 2 hour project and way overcomplicate it for no good reason other than to have fun. What else is a Home Shop Machinist to do?

Cheers,

BW

gundog
07-13-2006, 01:58 AM
Nice work Bob.
GD

Evan
07-13-2006, 02:21 AM
I like it. I also like the locking system but I don't think the name "split cotters" is correct. However, I can't think what they should be called.

BobWarfield
07-13-2006, 02:28 AM
I like it. I also like the locking system but I don't think the name "split cotters" is correct. However, I can't think what they should be called.

From the Machinist's First Bedside Reader:

http://www.powells.com/cgi-bin/biblio?inkey=4-0969098022-0&show_locs=yes

Lautard calls them split cotters and I have seen the practice used by many others. Carter, for example, has a clear explanation here:

http://www.cartertools.com/brooketh.html

The following Google search yields a number of interesting split cotter references:

"split cotter" clamp

They can also be a nuisance for some applications as they may hang up if not made pretty precisely. I have heard of some folks inserting a spring between the halves to alleviate that. Perhaps because I made mine according to Lautard's method, they seem to fit well enough that this is not an issue.

Best,

BW

IOWOLF
07-13-2006, 06:14 AM
Wow ,looks better than my store bought version. ;)

JCHannum
07-13-2006, 08:01 AM
That is an elegant vise stop. Most are cobbled up from scraps and bits welded together, usually with as much slag as possible.

Split cotter is proper terminology, though possibly British in origin.

If they are sticky in releasing, as sometimes happens, a short piece of rubber hose, like fuel hose will also aid in their release.

The Zamac split cotters Atlas uses on the tailstock clamp will benefit from this. I think the softer materials tend to hang up more than harder.

Mcgyver
07-13-2006, 08:52 AM
good job Bob, that came out very nice. afaik theyr'e split cotters, a very handy clamping device!

Evan
07-13-2006, 08:59 AM
I misunderstood the design. I did not realize the clamping was done by separating the pin in two pieces and drawing them together. I was under the impression that the cutout on the pin was drawn to one side by tightening the knob resulting in clamping action. It would seem to me that would be equally effective and easier to make. It also would not be necessary to bore the pin, merely thread it on one end for the knob.

In that case it would not be a "split" cotter.

JCHannum
07-13-2006, 10:00 AM
Split cotters offer several advantages over the simple wedge type of clamping system.

They apply powerful, positive gripping power.

They apply clamping pressure uniformly from two directions, and tend not to move the part being clamped.

Since the clamping forces are opposed, there is less tendency to mark or deform the clamped part as a wedge type clamp would.

They are self releasing. Sometimes, they may need a little help as mentioned.

They are not difficult to make, and add a definite touch of class to any project.

My Lautard inspired boring head uses a split cotter to retain the boring bar;
http://members.aol.com/jchannum/bh

BobWarfield
07-13-2006, 10:59 AM
Wow! Nice boring head JC.

I believe it eloquently speaks of our respective skill levels. A boring head versus a vise stop is somewhat on the order of a doctor who cures hang nails versus a brain surgeon. LOL.

I chose the split cotters for this application because they promised a lot of clamping force for very little finger pressure, which I arbitrarily deemed important to the project. I must say that I am still very much a "lathe guy" and a noob on the mill. I made all of the lathe related parts in about 1/4 of the time it took me to get the clamping blocks done, they were fast and done almost without thought or much reference to the drawings.

However, I learned a lot and will be much faster next time. In particular, if you checked out my web page on the vise stop, I actually learned the value of a vise stop before I had one. Given the symmetry of where the holes where drilled, it saved me loads of time once I figured out how to use a Kant-Twist in the stand in role as a vise stop:

http://www.thewarfields.com/img/Toys/MachineTools/MillStuff/KurtViseStop/P7083544.JPG

It let me get holes drilled at two ends equadistant from the ends more quickly, and it let me swap cutters less frequently without fear of losing my spot. Heck I even finally got marginally proficient with my edge finders. All in all, an excellent early mill project.

I'll be saving that boring head for MUCH later, though!

Best,

BW

SGW
07-13-2006, 11:08 AM
Guy Lautard talks about the non-release problem. His solution is to make the space between the two halves a little bigger (i.e. take a little off each end) so there is less "wedging" action and more pure "clamping" action.

I'm a big fan of split cotters. They're a bit of trouble to lay out and make, but they work incredibly well.

Cecil Walker
07-13-2006, 11:13 AM
As usual, great work Bob. Now, another project on the to do list. Thanks for posting.

IOWOLF
07-13-2006, 01:10 PM
Bob, I demand your next project is a clamp type vise stop. While a Kant twist clamp works, it's just not right and there is many times where a widget stop won't either.

Peter N
07-13-2006, 02:20 PM
Nicely made Bob.

Peter

JCHannum
07-13-2006, 02:41 PM
Thanks Bob, but the boring head was made early on in my HSM career. It reflects the usual collection of screw ups & OH Sh**'s most of our projects have. The trick is to make it look good in the end.

BobWarfield
07-13-2006, 04:22 PM
RE: Bob, I demand your next project is a clamp type vise stop. While a Kant twist clamp works, it's just not right and there is many times where a widget stop won't either.

You are absolutely right and I was thinking the same thing about 30 seconds after I really got to liking the Kant-Twist. I'm adding it to the list.

RE: It reflects the usual collection of screw ups & OH Sh**'s most of our projects have. The trick is to make it look good in the end.

I've decided the "trick" is to choose the angle to photograph that is most flattering and just not to talk much about the rest! The "Blur" function in PhotoShop also helps the impression of surface finish tremendously. LOL. You will note I got so excited about "finishing" I didn't even clean the Dychem off one of the blocks. I will probably apply some cold blacking solution to them which I have had good results with in the past.

Best,

BW