[QuinnSjoblom]

im trying to find a tool, but i dont know what its called if it exists. Might need to be custom made, not sure. Attached is a pic of the part to be milled, and the tool needed. This is a small delrin link end that will be popped onto a 5mm steel linkage ball. a 4.5mm hole is first drilled through the link, Then the lollipop drops down in the center and interpolates in a circle to form a 5mm sphere socket. So the tool needs a 2.5mm radius, but the diameter squished down to 4.5mm max, preferably 4.25mm or so. Ive found plenty of undercutting tools, but they are a spherical end which wont work for this. Does the tool im looking for exist? Or most likely gonna need custom made? The 5mm socket size is also not required. I will be making both the linkage balls and the delrin link ends so something close to 5mm will work if there is something close in size.

[ChrisW]

Most likely it will be custom cutter

Harvey Tool - Carbide Keyseat Cutters - Full Radius

Sent from my MHA-L29 using Tapatalk

[Jim Dawson]

Why not just use a 4mm spherical lollipop, then do a 3 axis interpolation to cut the shape you want in the delrin. You're basically cutting a barrel shape in the work.

[QuinnSjoblom]

Most likely it will be custom cutter

Harvey Tool - Carbide Keyseat Cutters - Full Radius

Sent from my MHA-L29 using Tapatalk

Yeah I figured probably not gonna find something that will work as is. There is one idea I'm thinking about if a custom tool is crazy expensive. I could get a regular spherical 5mm lollipop, grind away one side of it, mount the tool in an eccentric sleeve to bring the cutting flute in slightly. Would only be a single flute cutting tool, but in delrin it may work just fine.

[QuinnSjoblom]

Why not just use a 4mm spherical lollipop, then do a 3 axis interpolation to cut the shape you want in the delrin. You're basically cutting a barrel shape in the work.

Not sure I follow. You mean like multiple stepovers to 3d mill the 5mm sphere with the 4mm tool? That would work, butbi also need to be very efficient with this part. Will be making potentially a thousand or so on my mill turn setup out of bar stock. Fully automated. Hoping to get cycle time down to 20 or 30 seconds each. I guess forming a 5mm sphere with a 4mm ball probably wouldn't take many stepovers to get a good shape. I'll consider that for sure

[ChrisW]

Yeah I figured probably not gonna find something that will work as is. There is one idea I'm thinking about if a custom tool is crazy expensive. I could get a regular spherical 5mm lollipop, grind away one side of it, mount the tool in an eccentric sleeve to bring the cutting flute in slightly. Would only be a single flute cutting tool, but in delrin it may work just fine.

Yes it should work same as thread milling using id thread tool for lathes

Sent from my MHA-L29 using Tapatalk

[burbingus]

I think Jim is on the money here. I think you should use a 5/32 in (3.97mm) lollipop mill to do this operation. The first pass would be around the center of the ring and remove the most material. The second and third passes would be at the top and bottom of the ring. At this point, your worst material location would only be less than one thousandth out of radius. If you did two more passes at the optimal spots, you would only be 0.16 thousandths off radius.

[QuinnSjoblom]

I think Jim is on the money here. I think you should use a 5/32 in (3.97mm) lollipop mill to do this operation. The first pass would be around the center of the ring and remove the most material. The second and third passes would be at the top and bottom of the ring. At this point, your worst material location would only be less than one thousandth out of radius. If you did two more passes at the optimal spots, you would only be 0.16 thousandths off radius.

Wow thanks! I was curious what the scallop height would be at different pass numbers but didn't get around to actually checking like you did. Indeed it does look like this would give good results pretty quickly. The 5 pass scenario with 1.6 tenth scallop is plenty good enough and plenty fast enough. Especially since this is delrin. Probably no more than a few seconds to get that done.

[deadlykitten]

hy
... 1 clamp ( faster & expensive ) : y lathe + lolipop endmill
... 2 clamps ( slower & cheaper ) : non y lathe + without endmill + custom fixture / kindly