Member postings for old mart

I'm sure you could easily remove the spindle, there are plenty of instructions about. I can remove the spindle of the museum's Smart & Brown model A in 15 minutes now, but I removed the entire headstock the first time, somewhat unneccessarily the first time I did it.

I have never cut gears, but I would think there is an online calculator available out there.

Re reading the first post still leaves me guessing what exactly went wrong, it was not his first backplate.

I have made several, including 1 from billet and 2 from rough castings. I prefer to make them from Boxford backplates as long as the boss has enough meat in it to produce 1 3/4" threads and register. The less machining cast iron the better, messy stuff. The threads, register and rear face are all produced without any disturbance or removing the backplate, so everything is in line. I have removed metal from the rear face on 3 backplates to match them up for the reverse locking mod on 4 backplates, and the front faces only needed about 0.001" tir cleanup.

Good news, keep us updated.

The posts referring to shoe repair remind me of some years ago at work. Chris, the charge hand in our fitting shop had the chairman call in with the sole falling off one of his shoes. It got mended easily and Chris put a notice on the door "cobblers to the management". It was an excellent place to work, the managment laughed just as much as everybody else.

I can't figure how the op managed to produce a drunken thread, or maybe it is just a bit loose.

Too much arthritis in my fingers for fine work now unfortunately.

I have R8 to MT2 adaptors for tangs and drawbars. I made the mistake of trying to drill out the restriction in the tanged one with a solid carbide drill and it ended badly for the drill. I could resharpen it, but it would mean removing 1/4" from the end.

Not many people would want to hold less than 1mm drills, and an er11 would still be preferable than an er25 for them. I also have a straight shank er8 and a new British Jacobs 1/4" chuck. You are entering the realms of drilling machines running at up to 15000rpm when using small drills, I wouldn't much like to drill 1mm with only 3000rpm available.

The wobble is a concern, but all backplates should be screwed up several times and then the front face skimmed till true. The only time I didn't have to true up was when I bought a 9" faceplate for the museum's Smart & Brown model A from a seller on ebay who had a low starting price, but had no idea what he was selling. One of his photo's showed the casting number and I took a chance and got lucky. I fitted it to the lathe and was just going to face it off, when something made me decide to check it first, it had a tir of 0.0005".

So few people have a first hand experiance of actually running registers, but there are many experts about.

Here is a list of the chucks and faceplates used on the museum's lathe.

6" Toolmex lightweight 4jaw independent. 160mm Chinese 4 jaw independent.

er25 collet.

100mm Pratt Burnerd 3 jaw scroll.

125mm Chinese Huhhot 3 jaw scroll.

2 off 5" Pratt Burnerd 3 jaw scroll.

160mm Chinese 3 jaw scroll.

6 3/4" Pratt serrated 3 jaw scroll.

7" faceplate with bolted on boss.

9" faceplate with bolted on boss.

9" faceplate.

As already mentioned, the register clearance varies from 0.0005" to 0.020", and the tightest one is hardest to fit.

The toolmex and the 5" PB's also fit on the rotary table without their backplates fitted.

I would think of a base made as strongly as possible, channel section comes to mind. Make sure that it is not too low when designing it. There are usually local professional welders who could make the stand to drawing, or weld up your precut parts. If you can manage the transportation, then the stand could be assembled in stages, and even feature part welded and part bolted construction.

The trouble with the glass is that you would have to start with optical flats on edge to test the theory properly. I used to live in a tudor cottage and the diamond panes in the windows were hand formed in small individual batches and were too uneven to be able to see through properly.

Interesting experiment, I don't think I will be trying it myself. I have heard similar said about glass, that it is not a true solid.

It is the centralising of the thread against the vertical face of the spindle that makes a backplate repeat its location every time it is refitted. We have at least 8 choices of backplates for the Smart & Brown model A with its 1 3/4" X 8 spindle thread. The register clearance varies from 0.0005" to 0.020" and they all repeat perfectly. The only exception to this is if your lathe spindle has square threads, they rely on the register being a good fit.

Certain alloys could be affected by the local heat of the laser.

If you use very small drills, an er11 with a straight shank would be better, and hold that in the er25. The only downside of this is a possible increase in runout which may or may not be eliminated by re aligning the holders.

If you have a digital caliper to hand, it makes conversion easy.

I must re read this thread and try out the offered solutions, there is nothing to loose.

Plastics are not the only things which can fail in a relatively short time when their enviroment changes. I picked up a small ammonite on the beach at Lyme Regis which was made from iron pyrites and took it to Exeter museum. They told me that they were common and many of their exhibits had disintigrated over the years after surviving for millions of years in the rock and clays after forming.

It's a perfectly sound idea. You will have to try out your drills for runout just in case some don't work so well. Collets can be bought in intermediate sizes and also inch sizes.

The bore of the ml4 bullgear is 1".