Hand press

[mcguyver42]

But on with the headway.  I measured the thread pitch of one of the upper dies with the brass metric thread pitch guage and found that it is 1.5 which may be common on machine threads, I don't know, but I've never heard of a 8 x 1.5 bolt.  I measured it again with the silver steel SAE guage and found that 18 course is a  perfect fit.  I measured a 5/16 coarse bolt and found the diameter to be .307, remember that the 8mm measured .308.   I tried a common 5/16" coarse nut  and lo and behold, it screws on just like it was made for it.  5/16' coarse is nearly if not identical to 8 x 1.5.

[toxo]

I'll add a sideways rant here. I'm building a hot foil press and the thermocouple that screws into the aluminium block is M6. I have M6 taps but being a belt and braces guy I bought three more on ebay for around £8 the three. The first thing that pissed me off was the thread pitch is not standard. Instead of being M6x1 which is standard it was M6x1.25 (which is standard for M8). The second thing that pissed me off was no one I knew had a M6x1.25 tap and the only one I could find anywhere was £17.50 . I'll only use the thing once. 

I got onto inkbird and suggested they change it because that amount of money could well tip the balance when considering the cost of the parts to build versus buying ready made.

[fredk]

Drill it out to M7 and fit M6 helicoils

[mcguyver42]

I was kind of thinking along the same line.  I poked around a little bit and didn't really see much in the way of m6 x 1.25 helicoils though.  Might be better off to just abandon the thermocouple and look for one without that oddball thread size.

[mcguyver42]

The other thing you could do is cut a groove into 2 sides of  the threads of the thermocouple  fitting, and let it cut it's own threads on the way in.  I don't know how well it would ever come apart again, but it would go in and get tight

[toxo]

It's amazing how we ideas people will always find a way. I went the easiest way. Pay £17.50, use it once and put it back on Ebay for £15 used. Just hope I don't break the bloody thing.

[mcguyver42]

Well that sounds like the best repair.  Let us know how your heat imprinter project works out.

[fredk]

4 hours ago, mcguyver42 said:

I was kind of thinking along the same line.  I poked around a little bit and didn't really see much in the way of m6 x 1.25 helicoils though.  

Just as a note for others looking in. Helicoils, some of, can adapt to the thread.

eg. I/we fitted some M6 Helicoils into some drilled holes and screwed 1/4 inch bolts into them on my 1930 Austin . It wasn't an option to change fully to M6 bolts

[toxo]

3 minutes ago, mcguyver42 said:

Well that sounds like the best repair.  Let us know how your heat imprinter project works out.

Will do Mac. I have all the bits now. Biggest job now is cutting down the aluminium lump. It's 4 inches in dia and 4 inches tall. Now, not being a thermo guy I'm pondering which way to cut it. I have three 120w heaters (around 9mm) to sink into it along with the thermocouple. I don't know how thick to cut it before it's just wasting heat and taking longer to heat up. I think about an inch will do but that's a guess. I could leave it in the round and just lop off an inch or so. I could cut it "lengthways"  and have it 4 inches square. No doubt clarity will creep up on me.

I've hijacked this thread enough. I'll start a new thread when I update.

[mcguyver42]

Creeping Clarity, well said.  Tapping a helicoil to a different thread, I never thought about that.  Can they came back out if they need to and then go back in again?