Member postings for old mart

If the old safety valve still exists, then refurbishing it would be a better way to go than redesigning it.

I assume that you took it off because it is so worn that the backlash is unacceptable. When the thread is worn, the wear may well be biased to one side, if there are sideways forces, or even gravity. I realise just from seeing the dreadful design (only an idiot would bore a casting so close to the edge) that you worry about the concentricity, but would it matter if the replacement was made properly?

Don't worry too much about my ranting about the quality, I have seen the guts of a Tom Senior mill, and the quality of that particular example leaves much to be desired in design and the dreadful casting quality.

Edited By old mart on 25/06/2020 20:33:57

Edited By old mart on 25/06/2020 20:34:28

Makes you wonder why he didn't hit the hazard flashers and steer for the hard shoulder.

Unfortunately the government guidelines for delivering parcels gives the couriers carte blanche with the drop offs. Just dump it and run is the order of the day.

To find if the thread in the nut is concentric with the od, all you have to do is screw the nut on the leadscrew and see if it runs eccentrically. I would bet on it being in the same centreline, these big threads have a way of producing optical illusions. What is the OD of the nut?

No idea, I,m not a native.

Dead right, postman Pat is your friend.

Run the blade of a penknife round the hole and when the hole is big enough, the ball and spring will come out. Then screw in a tap of the right size to grip it enough to pull the rest out. Some have a larger flange which would allow a lever like an old sharpened screwdriver to be used to prise it out.

I had one of their stationary engines bought at a jumble sale back in the sixties. The screw in safety valve/ water filling plug had a very poor seal. I cut a short section out of a bike pump connector to replace it. I guessed the length, not having any means to test it and was lucky not to have blown myself up.

Best of luck with it, I would have been able to help, as up until 11 years ago, I lived in Godalming. The l is indeed sounded, Godal (like waddle) and ming (like a vase). Its Weston Super Mare now, there are hundreds of people in the sea during this hoy weather.

Best of luck with it, I would have been able to help, as up until 11 years ago, I lived in Godalming. The l is indeed sounded, Godal (like waddle) and ming (like a vase). Its Weston Super Mare now, there are hundreds of people in the sea during this hoy weather.

Sorry, Andrew, I thought it was bigger, I blame the heat, 33.8C at the moment. The cutting length on your example would be ideal.

It was harder than I expected to find a source of relatively inexpensive 3mm cutters with a 3mm shank, they commonly have bigger. Cutwel have some on special offer which are coated for steel, but not intended for hardened steel. I hope the link won't get me into trouble.

**LINK**

Go for stub length 3.2mm (1/18" solid carbide cutters, if the shanks are too long, then score right round the shank with a diamond file and snap them off. If you put the cutter flute end down in a vise with soft aluminium jaw protectors and put a tube over the unwanted end, they will normally snap off very well.

Good video which is hardly likely to worry our moderators. Now your problem is the very high speed of celestial objects, which gets worse the further you are from the polar alignment. The only way around that is to mount the camera on a motorised computer controlled telescope mount.

A J, your picture shows a 2mm slot drill, but the shank is al least 4mm. I had already asked whether larger size cutters would solve the problem, and there was no answer, so I assume that the chuck is too small. Perhaps a more capable machine rather than a router is required.

Will it take larger sizes? 3 and 4mm are much stronger and well able to use the speed of your machine.

Having a VFD controlled motor is an addition to using pulleys and back gear, not a lazy persons substitute.

How do you intend to produce a new nut in 3/8 x 12?

I used a metric trapezoidal leadscrew and nuts on an imperial machine. The pitch is 3mm, that is close to 0.118", so a crosslide scale with 118 divisions was made for the lathe. The worn out original was 1/2 X8 ACME.

Tracey tools has ACME taps, rh and lh, but the 3/8 is 10tpi, and new leadscrews would be required. You will probably find that both nuts and matching threaded rod are the only way to go.