Member postings for old mart

If you are not sure, just fit one of the surplace rods, zero the mic mechanically and measure how much is projecting.

Edited By old mart on 27/04/2021 14:14:34

Chrome plating is not a recommended surface to run with bronze. Hardened steel is best if you can achieve it.

Welcome to the forum, Andy, the QCTP is not essential immediately, as you can get by with shims made from any thin metal you can get your hands on. Have a look at the Arc site on this page, they have a good choice of tooling.

Dead right, Howard, I am pleased to get to +- 0.001" ,0.025mm for all but exceptional jobs. I worked many years in the manufacturing of aircraft components and rarely saw tolerances tighter than +- 0.0005".

Steviegtr has recently fitted one to the knee of his Tom Senior, he could confirm if the limit switches are mains voltage or lower.

I have looked at those, and there are two types, the more powerful having an advertised torque of 450 inch pounds. Some of the sellers say their stock is in the UK, but lower in the listing, mention Switzerland. The possibility of getting a lot of import duty and costs added tend to put me off buying.

The original rods should have been ground and lapped square at the bottom end, but you can get pretty good results with facing off in a lathe.

Really nice and so tiny. Now try making this limited slip diff:

**LINK**

Welcome Martin, thats a nice little lathe, you should find something to make a swarf catching tray.

The teeth of a rack, being of infinite diameter have straight sides, so the round pin idea is sound.

I have a couple of mechanical Mitotoyo depth mics and during my work with aircraft parts, I had to measure the stroke of a hydraulic landing gear lock for the Airbus A320. The movement was within the mic range, but I still needed two of the rods. I got the toolmakers to make me a custom rod which was halfway between and then could measure the stroke in one operation. The rod was silver steel with a pressed on end. You could easily make rods which would not have to be exact lengths if you also have a set of slip gauges. The digital can be set to zero at any point, so the exact rod length does not matter. Turning the ends of each rod with a tool set exactly on centre will give a rod that is better than 0.0001" at the end which is plenty for real life work.

As already mentioned, don't let the tools rub. We had a titanium fire in the toolmakers bandsaw when the apprentices were cutting tooling lugs off part machined aircraft parts. It caused a lot of smoke.

I have two, the large 700 is one of the first pressed steel ones, and I was very pleased to find that spare parts are easy to get hold of. I bought a set of feet and bump stops and noticed that the clamping screws and nuts were also available.

The only type of twist drill that will cut to size is a solid carbide stub, in a mill rather than a drill press. And after checking that the chuck or collet is running true.

Edited By old mart on 24/04/2021 16:55:31

We bought the drill mill as a basket case and it required a lot of work before getting it going. One problem that surfaced was sand left in the column falling out even after trying to stop it. I didn't want anything getting in the base joint when it was bolted up, so I found a huge cork (some helicopter part, don't ask me what) and pared it to size with a wood chisel ans stuffed it up the tube.

I s your lathe the one with the backgear spindle above the main spindle? Can you post some pics?

The backgears are in no way coupled to the leadscrew of a lathe, that is entirely different, which is why I said that you can pick any set of gears that will fit in the space available with the minimum ammount of modifications.

You may have to make eccentric bushes, but at least the swing of the movable gear can be adjusted. An interesting project, which is quite rare, we look forward to hearing of your progress.

https://www.technobotsonline.com/gear-size-calculator.html

Edited By old mart on 24/04/2021 13:55:46

Edited By old mart on 24/04/2021 14:01:39

We have a large round column mill at the museum, and as it is larger 500mm X travel and more Z and Y than the refurbished Tom Senior, it is definitely staying. You have to carefully plan jobs when using one as raising the column halfway through can be a bother. I have fitted a laser sight to the right side of the head which reflects off a window back and helps to get things within 0.002". I may change the sight for something with a better focussed beam some time.

I thought I would show you where the pipe actually was. Firstly, my cheap USB endoscope gave up the ghost and I was forced to go to Screwfix and get their cheapest self contained one. It is a Magnusson with a 1 metre flexible camera. It is much better than the broken one, not exactly cheap at £70, but easier to use and the picture is better.

I found the pipe below the floorboards, but hidden behind two joists. I cut a notch in the joist which ran parallel to the 40mm pipe and cut the pipe with the ratchet cutters, they don't leave a burr inside the pipe. The pipe was not properly inserted (about 12mm) and the rubber sealing bush was perished, no wonder it leaked. The strapped and glued adaptor has a smaller diameter boss than a modern one, so I had to make a one off coupling. I cut one end off a push fit coupling and removed the raised lettering on the od. I bought a 40mm tee with the screw up ends and the plastic rings just fitted the coupling and I could fit one of the rubber seals. The seal was too tight to push into the boss, so I had to reduce the seal od by 1mm using a scalpel blade. Wilr plenty of silicone grease on everything, I just managed to push it home. A new length of pipe 35mm longer than the original was fitted to just reach the inner wall of the 110mm pipe. As the ends of the old and new pipe were touching, I cut the centre stop out of a pushfit coupling and made a sliding joint.

Having the exact reduction as original does not matter, getting a set of gears in the space available is your task. Having a mill would help a lot as there could be some special parts which cannot be bought. There are some companies which can make new gears, and you are able to use the old ones for patterns.