Member postings for old mart

I kept the taper turning attachment set at the MT2 angle just in case I wanted more made, and it was not used. About a year later it had to be reset for another job. Even a CNC would struggle to set the exact angle, it needs to be better than +- 0.0001" over the length of the taper, which is why they are finish ground, normally between centres.

From a design point of view, the three way has advantages over the four way. The Smart & Brown model A at the museum has a four way as standard holding 20mm tooling reduced in height to 17.53mm to eliminate the use of shims. The tools are too long to hold four without far too much overhang, and the toolpost that I made for the second brand new compound that I bought on ebay is a two way because of this. A three way would not have the length limitations of the four way. One remedy possible would be a larger square for the four way, but that would suffer from overhang and increased flexibility. I have a larger four way toolpost, but that is used directly fixed to the cross slide for rigidity and primarily intended for boring bars up to 32mm.

At the moment I am finishing the longer improved cross slide for the Atlas 12 x 36, and although I had bought some 12mm tools for it, the slightly lower design for the compound to sit on will exactly fit the same tools that the S & B uses. We will make some thicker shims for the 12mm tools.

So it is an NSU engine, my friend had one for a while and we shoehorned the carburettor from a Villiers Midget lawnmower engine onto a home made manifold for it. The beast would go nearly 40 mph. One interesting thing about that motor was the chrome bore in the aluminium cylinder, his was worn right through over about 20% of the surface and it still ran.

There was a moped engine with a 2 speed gearbox, Mobylette or Motobecane, maybe. I am surprised that the plug is 12mm, though, back in the days it was 14 and 18mm and the first use of 10 and 12mm plugs was by Honda which was a novelty at the time. The approximate bore sizes of the plug thread in the head would be 10.4mm for 12mm and 12.5mm for 14mm.

You were lucky that day when you tightened down the compound. I find that having a selection of MT sockets or adaptors helps a great deal used as test pieces. It is possible to detect which end of the taper is loose when the socket is held lightly in the fingers. As the fit gets close, a little engineers blue will enable a perfect fit. Of course, getting the angle perfect will be hit and miss. I use a proper taper turning attachment on the Smart & Brown model A, but this although able to be much more easily finely adjusted than any compound, it is still much too coarse to get Morse tapers without trial and error. It is important to get the tip of the tool exactly on the centreline with any taper. Unfortunately every different size of Morse taper is a different angle.

You will have to sit your level on a suitable parallel to clear the prismatic bed, and shim the headstock end temporarily to get the bed close enough to see the bubble. You might find a twist, or the bed might be perfect.

Depending where the sump drain plug is relative to the oil pump, it might be possible to use a flexible bore scope after an oil change.

Bazyles method would not need the level and is a good idea. I added a block of aluminium to raise up the headstock of the Atlas12 x 24 lathe to allow room for adjustable "levelling" at the tailstock end. So far the lathe bed has not needed any adjustment and is very accurate with the tailstock end loose.

I bought a box of diamond burrs at Lidl the other week which will fit most of the dremel or clones. They would definitely remove the heads, no matter how hard they are.

Ian, could you use these results to move the headstock and retest? Also, a set of tests at the top of the bar rather than the side would check the other variable. I don't know just how sensitive a level would be needed to find any twist in the length of the bed. I have two Moore and Wright levels, I will try testing them for sensitivity and if one looks promising, I could lend it to you.

Edited By old mart on 13/06/2023 16:26:02

Edited By old mart on 13/06/2023 16:29:14

Edited By old mart on 13/06/2023 16:33:46

Is there any way to see the oil strainer fitted to the pump inlet?

Not being into clocks, and not knowing any better, I would strip out the plates, line them up and use the undamaged hole in the other plate to line up for drilling. I would use a solid carbide drill which has much greater stiffness than hss and loctite a purchased repair bush in place.

The play you have just achieved would actually be less with the hydrodynamic cushioning from the oil, and I think you would try some actual turning now. The lathe is small, and you will be able to make the measurements greater by bending the spindle, which would also be the same with a factory fresh lathe. Keep monitoring the heat build up at max rpm, the headstock should not get above luke warm.

Edited By old mart on 12/06/2023 19:43:56

I was not convinced that a wet rubber belt was a clever idea, but had not considered debris clogging the oil system. This is a major design fault, normal servicing could never never stop that happening.

I'm with the "high spots" people, I see no need to go overboard if the main journels are good.

We have just made a brass gib for the longer cross slide on the Atlas 12 x 24 lathe, it was the best size laying about and quite good. The original looks like cast iron, and if I had a choice some bronze woulf have been used. The aluminium might wear faster, but if it is available and can be adjusted easily, I see no reason not to use it. Keep the bed clean and oiled and all should be well.

Welcome to the forum, I would look at the Arc Euro site for some cutters and suitable holders. Also, you would do better to practice using some aluminium barstock,square or round. This will not tend to damage the cutters if you make a mistake. The aluminium will need a slight lubrication from something like WD40 to prevent it sticking to the cutting edges. Steel will also need slight lubrication with a tiny ammount of oil, tapping fluid would do to extend the cutter life. There are several good online sources of practical help, as you have found, some can be very advanced.

0.02mm in 50mm is not much. When you put a testbar in the chuck, even a rusty one, does it run true over at least 75mm, measured with an indicator on the cross slide? The spindle would have to be rotated by hand during the test. If that is not going to work, then an actual cut with a decent size bar, say 25mm steel or aluminium with about 80mm sticking out of the chuck. Both ends should be the same if the spindle is in line with the bed. Leaving the turned bar in the chuck, the headstock bolts can be slackened off and with the indicator, half the error taken out before retightening the bolts. This is trial and error, another skim should prove the results. The only headstock that I have taken off was not adjustable at all. I took the headstock off the museum's Smart & Brown model A when wanting to remove the spindle and found it was fitted to the prismatic bedways and line bored to the bed during manufacture. It only needed cleaning and bolting up to be perfectly aligned. Now I know how, I can remove the spindle in 15 minutes without touching anything else.

You could make one on a mill, but having a rotary table would simplify things. The hole could be bored first. If the lathe is big enough, that would be my first choice.

I have just popped down to the garage to measure the leadscrews on my old Warco 7 x 12 mini lathe. The original owner traveled from Frome to Warco's at 12 miles SSE of Guildford to pick it up. He had ordered an imperial model, but they had mistakenly provided a metric one. They gave him an imperial leadscrew and nut and one or two other things to pacify him. Measuring ten turns of the cross slide leadscrew, I got 9.97mm twice with backlash accounted for. The compound gave 9.70mm for ten turns. For normal turning these figures are plenty good enough because a micrometer would be the proper way to measure diameters.