andypugh

Productivity enhancement. I added a stripper and a foot-operated air blast to clear the completed parts. https://youtu.be/Bpb68xB6zTc 8 parts in 45 seconds, down to 20 hours to make the set. I had the idea last night that I should have drilled the lower follower for air blast, and then could have used the piston action to valve an air blast from the pressurised lower section. But it's all hardened now, so too late to be drilling holes. Soldering is likely to be fun. I would imagine that assembly with solder paste and then running over each tube with a torch would be the cheap way. (melting enough solder to dip a complete tube would be the quickest and easiest). I have experimented and found that the fins sucept well in an induction heater coil, which would be a high-tech way to melt solder paste.

One action to make the square, torus and petals. But no petal-turning-over. https://youtu.be/j0FX1ER4URY In the video above I make 5 in a minute. So 14,000 would be 46 hours of work. It could be much faster with a stripper to pull the sheet off the punch, and with an air-blast (maybe on a foot switch) to kick the finished part into a hopper.

I think that I could slightly re-design the existing punch and die so that EDM-ed pieces would cut the profile, while keeping hardened silver steel for the parts that do the forming. Probably an idea to keep in reserve if tool life proves to be an issue.

Would these do?

Looking at the eccentric layout of the punches I think that these probably stayed in one piece (which would make for a stronger but impossible to repair radiator)

It would also be an easy way to get back-relief, Though my current design has turned features on the punch and follower. (the earlier link should now show a rather re-worked design, using much smaller bits of tool steel.

Looks tricky to make, how about you try it 🙂 I have been slightly busy...

With the latest update, this is less of an issue as I abandoned the square follower design, so the square die recess is only 12mm rather than 30mm deep. This makes it rather easier to mill with a 4mm cutter.

And bigger is easier, as I don't have a slotting head...

I have what I think might be a workable (and makeable) design. https://a360.co/3pagTbb

https://en.wikipedia.org/wiki/Types_of_press_tools says: In general, cutting force (CF) can be calculated using the formula: CF =L x S x ζmax The square has approx 90mm perimeter, is 0.25mm thick and the shear strength is about 275N/mm2: So to blank out the square needs about 6kN. Zoro list a 50mm dia die spring with a stiffness of 700N/mm so even that would be compressed by 8.5mm. Cutting force could probably be reduced by faceting the die, as is done with Q-max cutters.

What is the corner radius? (not that there necessarily is a corner radius on the original ones) The torus is easy, I think.

I have given that some thought, and I think it has to be a second-op, I can't see a way to get the tip-turned shape out of a die that can also make the petals.

Each facet of a hexagon would make 1/6 of a gill.....

It seems that the faceted punch works just fine, which simplifies things:

It might need to be pointier. I think that, ideally it would be a double-action, where the square and inner ring is punched first,, then the spike comes up through the clamped, shape-locked ring and bursts it. But I don't know how you would do that. Possibly with a spring, but a spring stiff enough to punch the initial hole?

Ironically the tin with contents would probably have listed at a lower price.

I wonder if it is really as simple as a pentagonal pyramidal spike inside a square hole? (ie. like this https://a360.co/3pagTbb ) And would a hexagon work?

If you can find them at a decent price, this style of threading tools make a lovely whitworth-form thread in a single operation. https://www.ebay.co.uk/itm/284087318863

They would cut the thread that they had tooling for. In 1934 that would have been BSW / BSF. They wouldn't have randomly chosen (pre-ISO) metric or UN / Sellers just because it is theoretically cheaper to single-point. They might well have chosen to forego the crest rounding for the reasons you mention, but the thread angle is still rather more likely to be 55 than 60 (or 47.5, or 80).

Or you are under-thinking it when you suggest that an 1"-16 UN thread is an option. I am saying that it is unlikely that the thread form is UN, it is very likely to be Whitworth, and the two are not compatible. This has nothing to do with any of the standards, it has to do with the basic shape of the threads, which differ significantly.

I found a YouTube video of someone making their own: https://youtu.be/lw1b58kITxQ I was wondering if the lead angle of a thread affects the apparent thread angle when projected, but after a bit of 3D modelling, I have decided that the answer is "not enough to cause confusion"

But would a 1934 British car be using Unified threads? (Unlikely, Unified threads were invented during WW11) I just finished an M77 x 1 thread. I chose that size as I had a 76mm recess that needed a thread, and the 1mm threading tool was the one in the holder. If it had been the 1.25 insert then it might have been an M77.25 x 1.25 thread instead.

Or, indeed for fun. I made an M14.75 x 0.95 thread pair once. Just because that satisfied a mathematical optimum.

Looking at the thread crests might be informative. Flat crests would indicate that it is _not_ Whitworth form. Rounded crests, unfortunately, just mean that it _might_ be Whitworth form at that time period.