#7-30 Threading Die

[ChazzC]

Be careful. This doesn't work real well with good dies. They snap in half. Happened to me 3 times. Bought a cheap crappy die that didn't break. Much better.

Shouldn’t be a problem with quality adjustable dies: they’re designed to be opened & closed (specified thread diameter is mid-ish point of the adjustment).

 

[Susquatch]

Shouldn’t be a problem with quality adjustable dies: they’re designed to be opened & closed (specified thread diameter is mid-ish point of the adjustment).

Agreed. But we are trying to take a 6 to a 7 or an 8 to a 7. That's exactly why mine broke in the past. There is a big difference between a small or a big 7 and a 6 or 8.

Just suggesting a cheap die might actually be better in this instance.

 

[combustable herbage]

That's exactly why mine broke in the past. There is a big difference between a small or a big 7 and a 6 or 8.

I have been told a small five is as good as a big 8.

 

[140mower]

I have been told a small five is as good as a big 8.

.....you poor boy, just keep believing.....

 

[Susquatch]

I have been told a small five is as good as a big 8.

Must have a fat wallet.

 

[thestelster]

Well, I ordered a #6-30 split threading die from the US.

I made this little accessory to hold a DTI. I just have a 6-32 screw lightly screwed in place to test the functionality. When I get the the die, I'll make the knurled hold-down.

 

[PeterT]

You probably already went searching for a tap (to make a die). Seems like they are out there but uncommon

#7- 30 Special Pitch Tap, High Speed Steel

#7- 30 Special Pitch Tap, High Speed Steel

www.victornet.com

Same issue was discussed here. I hate niche threads for no good reason other than ransom

This Starrett screw thread a mystery (to me)

Anybody know what thread it is/was that Starrett used for fastening the extensions on their 995 planer gauge (aka 'No. 995 Universal Precision Gauge'). I can't find a screw thread anywhere in my parts bins that fits the internal threads on the block which are intended for attaching the bar...

www.practicalmachinist.com

Starrett threads and other headaches

What is the logic behind Starrett using oddball thread sizes? I have a 196 back plunger indicator set and the clamp uses one size 12-27? and the tool post holder uses another 9-32 as near as I can tell. Wouldn't it be more convenient for the user if they were both the same? :( And while...

www.practicalmachinist.com

 

[thestelster]

You probably already went searching for a tap (to make a die).

Actually, I didn't even think of that!

 

[Susquatch]

Actually, I didn't even think of that!

@PeterT

How would you do that?

Drill and tap a piece of steel,

Drill out the chip troughs.

Sharpen the chip troughs with a long cylindrical grinding stone.

Spilt the block to provide some thread relief.

Then harden.

?????

 

[PeterT]

Yes, essentially make an emergency die. I've only made one, so I'm no expert. The die is just reference photo for discussion. I used O1
- drill & tap the center hole (I made my thickness a bit more than standard to compensate for next step)
- make slight relief on front side of hole (seat of pants chamfer)
- drill relief holes (this was a bit tricky to make clean breakthrough. I pre-drilled a hole then used larger dia end mill plunged in)
- make slot (I just entered with bandsaw)
- I skipped the lateral expansion jack screw because it is more fussy work, but if you need this, now is the time before hardening
- filed a flat on OD to engage with a retention screw on my die holder
- torch to red, oil dunk-a-roo, temper at 475F my toaster oven max

As long as your die holder has a conical set screw you can open it up a bit within reason. I prefer my shop made ones because they additionally have more radial set screws to retain the die since there are no dimples. Anyways, it worked. Not quite as good as a well made die, but better than some of my commercial offshore crap. I had to make some custom pushrods with a weird LH metric thread I wasn't keen on spending $50 & waiting a week. Stock was 303 stainless rod. Anything tougher might put up more of a fight so really depends on how many you intend to make. I've seen some small dies like below that have no adjustment slot at all so maybe a function of size?

Another option might be to do the whole thread/relief hole operation in a rectangular bar of O1 vs. fussing around on the lathe & die holder. Then the tail end of bar becomes a little integrated handle. Maybe not as easy to align though but food for thought




laser or edm?

 

[thestelster]

I received the #6-30 die the other day. 7/8"OD HSS split die. Slowly opened it up a little at a time until one of the threaded parts of the planer gauge was able to screw on loosely. It didn't snap!!

Of course now that I opened it up that much the die wouldn't fit into the die handle. No big deal, I just scraped the inside of the die handle until the die went in, (sorta').

Made the new screw and parts using 1144 Stressproof I was thinking of hardening it? Maybe, maybe not. It's at around Rc22-25.

 

[ChazzC]

I received the #6-30 die the other day. 7/8"OD HSS split die. Slowly opened it up a little at a time until one of the threaded parts of the planer gauge was able to screw on loosely. It didn't snap!!

Of course now that I opened it up that much the die wouldn't fit into the die handle. No big deal, I just scraped the inside of the die handle until the die went in, (sorta').

Made the new screw and parts using 1144 Stressproof I was thinking of hardening it? Maybe, maybe not. It's at around Rc22-25.

Glad it worked out.

As delivered 1144 Stressproof is 22 – 25 Rc; Eric (Hand Tool Rescue) uses 1144 for many of his re-created tools, like the screwdrivers (not cheap, but at least shipping would be less for you, and they are beautiful):


He heats to Cherry Red, then quenches in oil (doesn't temper, and I read/saw somewhere that 1144 maxes out at ~52Rc so tempering not necessarily required). Oil is recommended to avoid surface cracking possible with water.

 

[PeterT]

I was looking into hardening properties of 1144SP once upon a time for miniature camshaft & came to the conclusion there are better options, at least for that kind of application. SP means it will distort less post-machining due to how its mechanically processed during manufacture. That's why its preferred for nonsymmetrical or other challenging mass/shape factors. Carbon content is 0.32-0.40%, about same as 4140 so I think similar hardening properties. I've also heard if 1144SP was shot peened for stress relief during manufacturing (as opposed to other methods?) the elevated temp works against you with higher risk of surface stresses.

Tool steel like O1 have 0.95-1.1% carbon which means it can be fully hardened & predictably tempered to a wide range of hardness values. Even in +/- local areas locally like the blade of that screwdriver. It doesn't machine like 1144SP but it isn't horrible. But, higher temps & quenching means elevated risk of distortion. But when you see parts like knife blades, which are probably the worst for shape factor in terms of warp potential, they are all predominantly 'tool steels' in that regard.

I'll check a book I have which might have more information. Here is a more anecdotal reference

Heat Treating info for 1144 Stress Proof

Been making punches and dies from 1144 Stress Proof and would like to heat treat them. I have a PID controlled furnace so setting temperature and soak time is no problem. I’m interested in hearing what has worked for others in the past. New to heat treating but not new to working with metal. Any...

www.hobby-machinist.com

 

[ChazzC]

I was looking into hardening properties of 1144SP once upon a time for miniature camshaft & came to the conclusion there are better options, at least for that kind of application. SP means it will distort less post-machining due to how its mechanically processed during manufacture. That's why its preferred for nonsymmetrical or other challenging mass/shape factors.

Per LaSalle (who developed it), 1144SP is “extremely” cold formed through special dies, and the goes through a high temperature, controlled process (sounds a lot like normalizing)

Carbon content is 0.32-0.40%, about same as 4140 so I think similar hardening properties.

0.32 - 0.40% C is 1141; 1144 is 0.40 - 0.48% per LaSalle and others. Still a medium Carbon Steel, but for many applications 50+/- Rc is fine and not having to temper is a bonus.