Threadmilling

[G Caputo]

I have a few questions for all you guru's out here. We had a job that recently kept breaking off a lot of taps. 3/8"-16 in sapphire 5 material I believe. We discussed threadmilling on a job when the proper time came. Well the situation came up where I don't believe it is the proper time, but was told we are going to do it on this job anyway. I am not looking to get in a pi$$ing match with the boss about this. (I already did and lost) It's 4140 ht material where as I have to threadmill 3/4"-10 x 1.50" dp and 1/2"-13 x 1.00" dp. I am limited to 2000 rpm's at the spindle (5" horizontal bar mill). We do have either a 3x or 4x cat 50 speed up head, but I am scared of losing rigidity and snapping them off. Also, the depth is longer than most standard threadmills I have seen. I was told HSS is just at the point where it isn't suited for the material. I am looking for anyone's input, tips, tricks etc. that would help me get this job done by threadmilling.

 

Thanks for any help guys/gals

[CAM-mando]

I would go with a standard carbide thread mill which is about 3/8" dia. for the 1/2-13 and grind the shank back just enough for clearance. Your spindle will get you up around 180 SFM. I don't like the spindle speeders myself. Also you want to start at the bottom and climb cut out of the hole.

[Ryeker]

4140ht that comes in around 28-32Rc right? If so you can do this with HSS, just got to slow it down (don't use the speeders..!). CAMmando is dead on with his comment of starting at the bottom of the hole and climb milling out, Swarf issues in the bottom of the hole if you try the other way around...

[Guest]

Call the tool manufacturing rep. Have him give you all the info.

[Toolfab]

Or call me and I can tell you everything you need to know. 4140 HT, NP.

 

I have all the specs that you would need and can walk you thru the progamming.

 

Drop me an email or call if you wanna discuss it more indepth.

 

[G Caputo]

Thanks for the tips guys

 

Paul,

I owe you a few

I really appreciate your help. If I ever get a chance to meet you (and I will find you at brickyard next year if you go), the first few rounds are on me. Thanks!

[fboike]

Try VNECORP.com they should have what you need

I use there tools for 3/4-10 2.25 inches deep.

in 58Rc A2 fairly reasonable pricing.

[Toolfab]

No problem Greg. Hope it all works out.