I have wanted to make this for a while...

[justgary]

300sniper -

I could almost swear that I have also seen carbide threadmills in the MSC Big Book (for pretty much the same price), and they have a 35% discount on cutting tools going on right now. If so, you could save about $15 on one.

Regards,

- Just Gary

[300sniper]

Originally Posted by justgary 300sniper - I could almost swear that I have also seen carbide threadmills in the MSC Big Book (for pretty much the same price), and they have a 35% discount on cutting tools going on right now. If so, you could save about $15 on one. Regards, - Just Gary

just about all the suppliers sell carbide thread mills. i hadn't seen one that could reach 1.5" deep into an internal thread until i looked at the micro 100 site.

thanks again for your post on making your thread mill. now i know it can be done if i do need something special. i need to start studying up on the hardening process. what grade drill rod did you use?

[thackman]

Thanks for the info Gary that was just what I needed. I've been confused as to why commercial thread mills (single tooth) were often only listed for a single thread size and reading through this cleared that up. It's because of the tip radius changes w/ thread size. You would want want a much larger root radius on a 2" bolt vs #6 screw.

The multi-tooth indexable threadmills seem to be fairly common (and expensive) but I haven't seen many like this. Enco has a few but they only go down to .250 which is too large for 1/4-20. I checked Micro 100's site and it looks like their threadmills are between $50 and $200. Which is far to expensive for me to experiment with but certainly reasonable for production. I'm going to make a few and get the process down and if it works out I'm going to try making one or two for ACME thread forms.

Does it matter if the thread root is rounded or flat? Most of the illustrations I've seen show rounded roots but the Micro 100 mills have flats.

[justgary]

300sniper -

The first tools (smaller threadmill and a taper reamer) were made from water-hardening drill rod. The bigger threadmill is oil-hardening, but I quenched it in water anyway (it is small, and would have quenched about the same in oil). I switched to oil hardening to try to help control warpage during the quench. Ideally, I guess you would want to grind to size after hardening.

I have some old peanut oil I plan to use for quenching whenever I figure that it really matters. It should smell good, at least.

thackman -

The shape doesn't really matter, but you could argue that a rounded edge will be stronger than a sharp corner. If you are after maximum strength, you probably want to round them. Sometimes (like dirty conditions) you want a little extra room at the tips of the threads so the junk has a place to go.

Remember to post pictures!

Regards,

- Just Gary

[BobWarfield]

Very nice thread, thank you for sharing it!

Best,

BW