Advice on making rounded end on a flat bar

great white

great white

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So I'm planning to make this:

lknjlnkj.jpg

It's a holder for a piece of Mr. Clean magic Eraser and Blue Sticky Tack. It's used to clean the sytlus tip on a record player. Believe it or not, they work really well for cleaning baked/caked on stuff on the Stylus. I've seen it first hand clean stuff off the stylus that commercial.retail cleaners won't even touch.

It's all pretty simple lathe work except that flat bar piece. I've got a lathe and mill, but neither is CNC.

I'm trying to figure how to round out the ends of the small flat bar.

I'm not good enough with the manual wheels on the mill to make it cut a round shape like that.

I've though maybe make straight cuts as close to the radius as possible and finish with a file, but that seems kind of tedious when I have the machines and tooling at hand.

What process woudl you use in my situation?
 
C-Bag said:
A rotary table.
Click to expand...
I have one (5"), but haven't used it much. How do I get such a tight radius on it? Seems I'd still have to master "etch-a-sketching" the hand wheels to get what I'm looking for?

Does it have something to do with how far out on the table radius you mount the bar? IE: Closer to the center = tighter radius?
 
great white said:
Does it have something to do with how far out on the table radius you mount the bar? IE: Closer to the center = tighter radius?
Click to expand...
You got it. The hard part is simply clamping it in the right place. Hint fixture it, so the other end comes out the same. :)
 
The rotary table is the hard way. You have an ideal application for this: Drill the holes, stick a short rod through this, then open your mill vise a bit and slip the flat bar in the slot vertically...the rod keeps the edge of the bar a constant distance from the center of the hole. Then mill off at the edge of the bar, loosen the vise and rotate the bar a few degrees, and keeping the endmill at the same distance, nibble off a bit more. Keep moving the bar angle around, and you'll mill a perfect radius end. You're nipping off the tangent lines, if that makes sense.

This works way better than it sounds.
 
Disc or belt sander is what I use, alternative is carbide radius cutter, and clamping is securely so it does not flex. Depends on the steel you are using. Rotary table, would need to make some form of clamping fixture at the radius point.
 
if there is a hole in each end you can make a "rounding the end" fixture so the piece pivots on the hole and use it like a very down marker rotary table.

(does that make sense or is a picture needed ?)

:)

Stu
 
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