Need a way to round corners

S

Stan

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My first project after purchasing a 6x26 mill. I needed a way to round the corners on this motor mount and this is what I came up with. 2-1" bearings, short piece of 1" shaft with a 3/8" threaded hole in the end and 2-3/8"x1"x3" pieces of stock. Used 2 bearings because they were floaters. Mounted the bearings back to back with the 3/8"x1" stock in between to be held in my vice and the shaft is held in place by 4 set screws. I used a counter sink machine bolt to hold the piece that I am rounding in place. This makes sure that the hole will be centered. The corners turned out as nice as the straight cuts. You can see pictures at http://www.flickr.com/photos/stanleygill/sets/72157632458663968/. Please advise me of other methods since I am new at this. Any help will be appreciated.
 
Those look pretty good. Just be careful to conventional mill as climb milling can grab and get you into trouble.

Other methods to produce arcs like that are the rotary table or just scribe an arc with a pair of dividers and belt sand them.

Tom
 
Other ways to do that are with a file (hehe), with a rotary table (which you kind of made a simple version of), or on a CNC machine with circular interpolation. Very fine work on that motor mount BTW, looks great.
 
This is an old thread, but a constant problem for me. Especially I would like to know some good ways (or any way) of rounding a corner radius where you cannot accept a through hole at the center of the radius. Yes, I have a rotary table, but it weighs a ton, takes a long time to set up, and generally is only practical for major jobs. This would be more of an impulse kind of thing to do when considering the almost completed project.

Help anyone?
 
12 inch disc sander. ;)

image_18029.jpg
 
Jim, that is definitely practical. I was hoping for something a bit more elegant! :)
 
I use a belt sander. It's possible to get very good results if you're careful and mark the steel with a scriber before you go to work. I clean
up the edges with file and emory paper. It does take time though.
Works best on thin stuff or aluminum of course.
 
If the radius requires a high degree of accuracy, for instance if it is a feature on a cam that translates motion than the rotary table is your best bet with a manual machine, if for appearance or clearance only grind it and finish by hand.
 
Thanks for your comments, No and P. I can only think that there is no good way to do this short of a full boat rotary table setup and that grinding is a time tested solution. Sad, but that's life I guess.

I wish some creative Hobby Machinist would come up with something though.

For example, for woodworking I have a set of corner rounding gizmos that fit over a corner and guide a router or router table around. Makes perfectly smooth corners in seconds.

Maybe if I knew faster ways to set up the rotary table...takes me forever, now. And the thing is just plumb heavy. Ah, me. :)
 
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