How to cut something round on a vertical mill?

[MrWhoopee]

If you have a through hole concentric with the radius, you can mount a pin for an axle. Then clamp the part in your vise with the pin resting on top of the two jaws of the vise. With the flat of the part parallel to the table, set your end mill to just touch. Loosen the part and rotate it slightly and make a pass with the end mill. Continue this procedure until you have worked your way around the radius. Clean up with a file as necessary. Depending upon how many steps you use, you can machine a very precise radius.

No through hole? Then machine two round bosses on the ends of the part that are concentric with the radius. This can easily be done on the lathe using a four jaw chuck. When you are finished cutting the radius, you can mill off the bosses.

Here's a video of that method.

 

[Jimsehr]

Yep, just not as thick. Maybe 3/8-1/2 of that.

I have made a few radius or ball turners and don’t see a reason for making that shape for a plinth. Why not just use a round shape? Google ball turners and see how others are made.

 

[great white]

So, I’ve got it sorted. At least sorted to where I can cut a radius.

I took the 3” rotary table apart and found its typical “made in China” quality. The table had such horrendous backlash because the way it was machined the leadscrew had approx 3/16 (!) of slop where it could oscillate back and forth. When the cutter met the material, the table didn’t have a chance to keep it from bucking and chattering and eventually just jamming the table up solid.

I was able to take the bushing that the leadscrew passes through and shave the thickness down to where the leadscrew only had a few thou to move back and forth. Any tighter and the leadscrew would jam In its bore.

Then I stoned and lapped all the internal components so they ran smoothly and mated well.

When I put it back together I gave everything a generous coating of white lithium and adjusted the leadscrew/table gear to have minimum backlash but still able to move smoothly.

I dropped the table in the mill vice and locked it down quick and easy for a test cut). Then bolted the work piece to the table.

Tried a little side milling and while the cuts must be ridiculously light and the feed ultra slow, I’m able to mill the radius I need. It will take a while to do the whole piece, but at least it cuts with minimal fuss.

I also think it may work for doing the 45 cuts on the back edges if I line up the work piece and lock the rotary table (it has a lock screw).

Time for bed tonight, but back to machining my plinth for the ball cutter tomorrow….

 

[Aaron_W]

So, I’ve got it sorted. At least sorted to where I can cut a radius.

I took the 3” rotary table apart and found its typical “made in China” quality. The table had such horrendous backlash because the way it was machined the leadscrew had approx 3/16 (!) of slop where it could oscillate back and forth. When the cutter met the material, the table didn’t have a chance to keep it from bucking and chattering and eventually just jamming the table up solid.

I was able to take the bushing that the leadscrew passes through and shave the thickness down to where the leadscrew only had a few thou to move back and forth. Any tighter and the leadscrew would jam In its bore.

Then I stoned and lapped all the internal components so they ran smoothly and mated well.

When I put it back together I gave everything a generous coating of white lithium and adjusted the leadscrew/table gear to have minimum backlash but still able to move smoothly.

I dropped the table in the mill vice and locked it down quick and easy for a test cut). Then bolted the work piece to the table.

Tried a little side milling and while the cuts must be ridiculously light and the feed ultra slow, I’m able to mill the radius I need. It will take a while to do the whole piece, but at least it cuts with minimal fuss.

I also think it may work for doing the 45 cuts on the back edges if I line up the work piece and lock the rotary table (it has a lock screw).

Time for bed tonight, but back to machining my plinth for the ball cutter tomorrow….

A 3"rotary table is really small for a mill that size, I have a 4" RT on my Sherline. So not only is your rotary table cheap, it probably is meant to be used on a much smaller less powerful mill. I have a 6" RT for my Clausing, which is roughly the same size as your mill.

Sounds like you are making it work, but you may be asking a lot of it.

 

[great white]

A 3"rotary table is really small for a mill that size, I have a 4" RT on my Sherline. So not only is your rotary table cheap, it probably is meant to be used on a much smaller less powerful mill. I have a 6" RT for my Clausing, which is roughly the same size as your mill.

Sounds like you are making it work, but you may be asking a lot of it.

Yep, making due with what I’ve got. There will be a larger, better RT in the future. But having just dropped roughly 5G on the mill and some tooling, my bank account needs a little “recovery time” before getting hit again…

 

[great white]

Getting there:





Still needs some finishing work with the files, but its pretty close to done on the top.

Next is to bore the hole to mate it to the Atlas cross slide and then drill and tap the holes for the retaining pins.

Pretty happy with it so far….

 

[Just for fun]

Looking good!

 

[great white]

Got the bore cut to mount it to the Atlas cross slide:



Tomorrow I’ll drill and tap the holes for the hold down pins.

Getting close to the finish!

next project will be a tube bender, which I will use the ball cutter to make the die.

Once the bender is built, I can start building the frame for my CB650 project.

I also have to slip a hydraulic press build in there somewhere…

 

[Parlo]

If you want to make a D shape on a mill
Make a rectangular shape then mill the two radii with a corner rounding cutter.
Flip over in the vice & machine the chamfers.
Cut the part off from the parent material.

 

[great white]

All done and ready for work;




It’s just a touch high for on center. About 0.005. I’ll gove it a try and if needed, shave another 5 thou off the plinth.