[KSky]

I am cutting some 1.25 x 20 threads in aluminum and while they work pretty well, it's not perfect and they come out rougher than I would like.

It's easier with pictures so this is what I am up to. I am used to thread milling and I think I can do better here.

[jeffrey001]

There's some melted aluminum on the tip of the tool.

It will not make a really good finish.
Jeff

[saabaero]

There's some melted aluminum on the tip of the tool.

It will not make a really good finish.
Jeff

If you’re not already, try using coolant or lubricant such as WD40.

[KSky]

That's actually just a chip sitting there in a wrong spot, I should have brushed it away before I took the picture, the cutting edge looks exactly the same as the unused ones. I'm using flood coolant washing it pretty good the entire time. Im more curious about my recipe.

[saabaero]

That's actually just a chip sitting there in a wrong spot, I should have brushed it away before I took the picture, the cutting edge looks exactly the same as the unused ones. I'm using flood coolant washing it pretty good the entire time. Im more curious about my recipe.

I don’t think it’s the problem but I would be using far fewer than 16 passes for a .040” deep thread in aluminum!

[jeffrey001]

I don’t think it’s the problem but I would be using far fewer than 16 passes for a .040” deep thread in aluminum!

That could be it, maybe the tool is just rubbing without cutting any material, I would cut in half the number of passes.

Jeff