Hard Turning Thread Insert

[Micmac1]

We have a job that needs a 5/16-24 thread turned on some hardened steel (HRc 62). The OD is already to size, only 1pc so grinding is not really economical, however it may be our only real option. Anyone have experience with threading tools for material this hard?

 

[EmGo]

We have a job that needs a 5/16-24 thread turned on some hardened steel (HRc 62). The OD is already to size, only 1pc

Eeeuw, I can't see the sharp little corner of a threading insert holding up.

Unless you have a thread grinder nearby, bench grinder bolted to compound and tilted, dress a 60 on a skinny wheel, and do it in a lathe. I bet you end up there anyhow, may as well save a bunch of time messing around.

 

[michiganbuck]

For one piece sending it out may be best.
Too bad you don't have your location listed because someone may have some advice on where it may be done...and for better price.

*A darn shame so many PM members don't list location.

 

[cnctoolcat]

I know it's not for threading, but Seco makes inserts specifically for hard turning that are the cat's meow. The insert grade starts with an "HT"...

These things have to be the best carbide tool solution for hard turning out there!

ToolCat

 

[Micmac1]

For one piece sending it out may be best.
Too bad you don't have your location listed because someone may have some advice on where it may be done...and for better price.

*A darn shame so many PM members don't list location.

Massachuetts

 

[bigjon61]

We thread Thomson shaft for a job about once a year and surprisingly have great luck with regular carbide threading inserts. 62 really isn't really too hard with today's insert grades, especially for 1 off parts.

 

[Mtndew]

Run it slow and dry.

 

[RC Mech]

For the price of an insert, send it out. I just did some die parts at 62 HRc with CBN CNMG inserts. At $70 per, I wouldn’t want to try threading.

 

[Micmac1]

For the price of an insert, send it out. I just did some die parts at 62 HRc with CBN CNMG inserts. At $70 per, I wouldn’t want to try threading.

Carmex Has laydown thread inserts they claim are good to RC 68, probably pushing it tho. I have tried to sub it out but the lead times are critical and everyones fairly busy.

 

[Digital Factory]

We thread Thomson shaft for a job about once a year and surprisingly have great luck with regular carbide threading inserts. 62 really isn't really too hard with today's insert grades, especially for 1 off parts.

What diameter shaft and thread? I thought those were case hardened?

 

[Mtndew]

I thought those were case hardened?

They are.
It can be done, we've done it from time to time. Just need to slow down the R's and run it dry preferrably.

 

[Digital Factory]

They are.
It can be done, we've done it from time to time. Just need to slow down the R's and run it dry preferrably.

I meant to point out that the case hardening doesn't go down that far, so the material gets softer as the diameter gets smaller.

If OP's material is thru hardened, it can be challenging because single pointing is generally pretty abusive on carbide.

That said, worth a shot if the material is replaceable.

 

[Micmac1]

I meant to point out that the case hardening doesn't go down that far, so the material gets softer as the diameter gets smaller.

If OP's material is thru hardened, it can be challenging because single pointing is generally pretty abusive on carbide.

That said, worth a shot if the material is replaceable.

It is a non carbide tipped micrometer spindle.

 

[Dan from Oakland]

These guys are great for 1 off or production thread grinding.

www.myersprecision.com

 

[RC Mech]

Carmex Has laydown thread inserts they claim are good to RC 68, probably pushing it tho. I have tried to sub it out but the lead times are critical and everyones fairly busy.

I misspoke, they’re Kyocera Ceratip CNGA.

Only two cutting edges. Expensive but they worked well.

 

[bigjon61]

What diameter shaft and thread? I thought those were case hardened?

7/16-20. Case depth usually varies from .03-05" so the root of the thread may break into the soft material underneath. I think we usually do 10 pieces at a time for our customer's tool crib inventory when we do them and we usually don't break an insert.

Edit: The 7/16 is on one end of a turned down 3/4 Thomson shaft. The other end gets a 3/4-16.

 

[gregormarwick]

CBN screwcutting inserts are horribly expensive, even compared to CBN turning inserts...

For one off, you can probably* do it with carbide if you run slow enough and don't mind destroying a few edges of your insert. Alternative flank infeed is a useful strategy for hard screwcutting.

I have cut threads in the upper 50's with carbide, but at 60+ I have always gone straight to CBN, so I wouldn't want to stake my reputation on it working...

 

[CarbideBob]

Interesting question.
Thomson shaft is way different than though hard so wonder if you need CBN.
Take any threading old tool . Notch it, put a piece of scrap CBN on and then grind it on the swing.....My options are not yours.
Here the rubber meets the road. As a one, two, three corner tool from a PO the price is just nuts.
Tialn coat on a good base off the shelf tool?

 

[EmGo]

Probably won't help you this time but I've thought these could be super handy -

https://files.catbox.moe/4o0vcl.mp4

You could make your own easily enough, it's just a spin fixture geared to a slide, so as you spin the part the gears drive the spinning chuck forward. Good for the occasional ground thread or worms or even oil grooves, any sort of helix in a hardened shaft.

Or you could just buy one, but what fun is that

 

[RC Mech]

Probably won't help you this time but I've thought these could be super handy -

https://files.catbox.moe/4o0vcl.mp4

You could make your own easily enough, it's just a spin fixture geared to a slide, so as you spin the part the gears drive the spinning chuck forward. Good for the occasional ground thread or worms or even oil grooves, any sort of helix in a hardened shaft.

Or you could just buy one, but what fun is that

First I’d over-build it and need a bigger surface grinder. Then PLC-ise it. Then I’d want it to do every thread in existence, have change gears and a dedicated wall display for every gear labelled and sorted. Then PLC-ise the downfeed on the grinder….

Where do I obtain the off-the-shelf time-saving option?