Acquired a Pultra

I went to the Dunstable Downs amateur radio car boot sale today.
I was expecting to get some electronic test equipment but came back with mostly mechanical engineering bits.
Find of the day was a Pultra precision lathe. I think it's a 1750 but have to check. Certainly 50mm center height. It is in fair condition and came with a lever action tailstock, 3 and 4 jaw chucks. No tool rest or slides though. The slides are probably the easiest parts for me to make myself. I have some miniature linear rail bearings that would be ideal. The same donor unit that hs the bearings, an optical scanner, also has some leadscrews. I will have to check them out. Not sure when I’ll get a chance to investigate the further, got a couple of busy weeks coming up. Other purchases included a unknown high speed precision drill press. It’s the kind used for PCB drilling. It is older and very well made. Direct drive from a universal (brushed) motor with the whole assembly sliding in a plain bearing about 2” in diameter. Needs a clean but looks OK. I’ve wanted a drill of this type for years. The universal motor will make it easy to add variable speed control.
Small items were a small Verdict lever DTI in the case with fittings, M&W depth micrometer and a small V block.

Cost was minimal, £40 for the Pultra, £10 for the drill and £4 for the smalls.

I did get a few items of test equipment too.

Robert.

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Nice one, Robert … let’s see some photos, please

MichaelG.

You did well there, then!

That's an impressive haul! ..what a pleasing day's work..

Photos of bed and head. Not taken any of the other bits yet.

Excellent !!

On that Manchester bed, I suspect it may be a ‘bitza’ … but there’s nothing much wrong with that: They were sufficiently tightly toleranced that components were considered interchangeable.

MichaelG.

Edited By Michael Gilligan on 21/05/2023 20:55:41

The series P … of which these are the beds, had a headstock more like a watchmaker’s lathe

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MichaelG.

I did wonder about the different finishes. At £40 including the chucks I was not too bothered It will be more of a bitza if I make my own slides... The headstock looks OK there is even some oil in it.

I think I've got a Pultra cross slide squirrelled away somewhere. I'll have a ratch ASAP and let you know.

Looks like today is your lucky day, not only a cross slide but the bit that bolts to the bed. I don't have any evidence that these are from a Pultra, but they look very similar. The pen is 142mm long. What I don't have is the very nice resettable dial, that was grafted onto a Cowells, which I've since sold. I have a feeling (no more than that) that I have another cross slide lurking somewhere, but I've been dragged out to attend to family stuff. Any more dimensions wanted just shout. If you're interested make me an offer 

Edited By duncan webster on 22/05/2023 12:11:04

Hi Duncan,

Message sent.

Robert.

Got a chance to have a closer look at the Pultra today. Befinately earlier bed. There was a CF-33 recessed collet in the headstock and I was a bit worried it might be stuck. The drawdar unscrewed by hand abd collet came right out. The 3 and 4 jaw chucks don't seem to have arbours to fit the headstock but the should not be a problem as balnk 10mm arours are available. The 3 jaw is a Bernard. It was left closedand has a bit of rust. The lever tailstock is also stuck so bothe of those have had a liberal application of Plus-Gas and are now soaking. There is a Jacobs style chuck with arbour and drawbar the fits the tailstock
I wnt to a local market yesterday and picked up a set of small collets. Seller didn't know what they were. Some had the CC Crawford mark and they looked about 8mm. At £15 it was a no-brainer. also picked up a thread gauge. total outlay £18. I measured them this morning and they are Pultra / Boley 8mm. Won't fit the headstock of the 1750 of course, but do fit the tailstock. Total of14 collets, mixed metric and imperial. And thanks to Duncan there is an incomplete compound slide in the post.

Robert.

I did some more work on the seized tailstock today. It's a lever operated model from a P type. I left it in a ziplock bag with plenty of Plus Gas to soak overnight. Still totally solid this morning and not responding to taps with a piece of wood on the tube while hand holding the tailstock. So I got the bed out and cleaned up the ways with steel wool and a bit of kerosine. They are in good condition but had one small, obviously recent, ding wirh a raised area. I dressed that off with a diamond file. I also cleaned up the exposed parts of the tailstock tube. Then fitted the tailstock to bed and clamped it with a piece of wood between the base of the tailstock and head. This gave me some mass to react force on the tailstock tube without having to over clamp it. I then warmed it up to about 40 deg C and applied more penetrating oil. Left it for an hour and tried a few light taps with a bit of wood. No movement. Time to bring out the heavy(er) kit. I applied lots of heat to the body of the tailstock with the hot air gun and tapped the tube from both ends with a small dead-blow hammer and a piece nylon to protect the tube. As soon as it moved one way I cleaned the rust off the exposed part with steel wool, turned the tailstock around on the bed re-applied Plus Gas and tapped it back until it exposed a bit of the other end. Rinse and repeat until the tube came out

I then cleaned the tube, the bore of the tailstock. and the locking slide. The precision and quality of these lathes is shown by the fit of the locking slide until I cleaned the outside of the slide and applied Plus Gas it was not obvious that this was a separate piece. Even after cleaning the plate slides in the slot with no detectable play and no obvious movement between locked and unlocked. It's coming together.

Robert.

Edited By Robert Atkinson 2 on 29/05/2023 16:13:06