Member postings for old mart

Computer keyboards don't have a "return" key.

Shouldn't take any time at all with 1mm cuts.

Some types of SS can be problematic to drill and tap. The tooling needs to be sharp so that it gets a chance to cut. Drills and taps gradually loose their sharp edges and should then be relegated to less demanding metals. Ideally, a selection of drills and taps of a given size should be kept in stock, and swapped around to find the best performing ones for each job. I have tapped a tungsten alloy called Densimet which behaves very much like SS for 2.5mm holes. I bought new Europa taps for hard steels, and they didn't work well. I am in the fortunate position to have a large stock of donated taps to try out and an ancient one finished the holes easily. I think that taps designed for aluminium might work better in work hardening types of metal, but have yet to test the theory.

You bunch of monkeys are more interested on your Meccano than my reply stating what threads are actually on Smart & Brown lathes.

You might try taking the calipers apart and cleaning everything, but that's just clutching at straws. My cheap ones have lots of foibles, my 30 year old Mitutoyo's never give any trouble at all.

Well, I tried writing first, then putting two pictures in and then posting, that didn't work. Then I wrote the text and added two pictures and scrolled down before posting, that didn't work either. Then I tried putting the pictures in first, which then left no room to place text, I didn't bother to post that.

Another try.

Just checking where my pictures go relative to the text.

The threads I have come across when working on the museums Model A are BA and BSF. No unified or Whitworth have surfaced.

I don't think it is magnesium, but a small sample will get tested just in case. Any repairs are limited as we do not have any welding facilities and the budget is, as normal, zero.

The centres looked a bit Colchester like, someone recognised them and got them for £45 plus postage. I have occasionally stumbled upon items which others have missed and got bargains.

Sorry, I had to re write the whole lot when the photo's wouldn't work. The original mentioned aluminium, and I missed it out afterwards. I'm pretty sure it is a casting, so the manufacturers must have overengineered it for whatever function it performed. The cables attached are at least 3/8" diameter. Some of the related parts are indeed steel forgings. The entire aircraft is a wreck, there is no danger of any part ever being in working condition.

The team restoring the Piasecki H21 have given me a piece of the mechanism connected to the front rotor head. It looks like a casting, judging from the granular surface of the break. It will probably have to have a section grafted in as the parts bent before breaking. The width of the H section is about 3".

Looks like you're winning at last, at least the bits are not so heavy to get into place.

You may have to try to remove the head completely from the column before going any further. Watch out for electrical connections when doing so. It will certainly be easier to manipulate without the extra weight and bulk.

With the head stuck at 45 degrees, and assuming the pin is back in place, it will require holding back while the head is returned to vertical.

Firstly, I'm only guessing about this. The head probably should only tilt 45 degrees either way, so it has likely hit a stop. You ought to re tighten the central bolt, as the head could be nodding forward and jamming. Taking the weight off the front could also allow the head to be returned to vertical. That spring loaded rod with the tapered end looks like it aligns the head in the vertical position.

The leadscrew end float is mentioned by Smart & Brown in the model A toolroom lathe instructions, so it would be equally important for any lathe.

Engine oil will be fine, avoid 3 in one. I would have recommended chainsaw oil until the thickness was explained.

The anchor point for the link could just as easily point towards the tailstock as the headstock. It might be possible to fabricate a clamp on fitting like a saddle stop to provide the anchor point, as long as it doesn't get in the way.                If you need to drill and tap the bed, 6mm would be plenty big enough, and the hole could have a grub screw in it just under flush when the collets were not in use.

Edited By old mart on 17/12/2019 13:35:17