ChazzC
Well-Known Member
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).
#7-30 Threading Die
- Thread starter thestelster
- Start date
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.
I have been told a small five is as good as a big 8.
140mower
Don
.....you poor boy, just keep believing.....
Must have a fat wallet.
You probably already went searching for a tap (to make a die). Seems like they are out there but uncommon
Same issue was discussed here. I hate niche threads for no good reason other than ransom
#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
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.
?????
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?
- 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?
