Lathes & M/C tools

[jrg1]

With hacksaw blades as thin parting tools always try to use only the HSS type, not carbon steel cheap blades, as they can be brittle.

 

Some makers use a compound type, Bi Metal, that has carbon mild steel as the main body and HSS bonded only to the edge to make the teeth, these are not much good for parting as the body is deliberately left soft, and can bend easily.

 

As far as I am aware junior size hacksaws are only made in carbon hard steel, and can shatter under stress, so the HSS blades must come from a 1/2inch or above size.

 

As no side clearance can be ground, they must be used with cooling lubricant when cutting steel, but can do brass etc dry.

 

The blade can have a holder made from steel bar, a saw slit in the end to take the blade and silver solder it into place, the heat will soften the steel, so heat again and quench in oil, then clean the blade and warm till blue to get back the hardness.

 

Stephen

Thanks Stephen-I thought all hacksaw blades were HSS

[Izzy]

Can anyone offer any advice please?

 

I have a small Sieg CO baby lathe which is now 4 years old and in the last week seems to have suffered PC board failure of some kind. Replacement boards are available, but cost around £90 and do not come with any warranty. It has been suggested that I might want to make sure the motor is okay and is not the primary failure by testing it out of the lathe prior to ordering a board, and that this should be possible by hooking it up to a 12v car battery charger. The motor is 230v DC and rated at 150watt and 0.9amp.

 

Sadly I do not own a car battery charger these days and wondered if there was any other way of easily checking the motor apart from taking it to my local garage and seeing if they would be able to test it. Although electrics is not a strong point I assume that just trying to hook it up to a spare 12v railway controller is not an option due to the low 1.5 amperage limit ( I am guessing at 12v the motor might draw quite a few amps?).

 

Or am I just showing my total lack of knowledge of electrics here? Any help gratefully received.

 

many thanks,

 

Izzy

[bertiedog]

Point number one, there are two motors, one mains, and one a coreless DC type, so it must be determined which it is first. With the Dc motor it is probable that it is the board at fault. Now if the motor is DC, then yes a charger or battery would run it, but the current is high at over 10 amps.

 

Under no circumstances must the DC motor be put direct on to 240 volt mains, and I would not recommend running the Dc motor on a charger really, as it will be only half wave rectification, and over heat the motor.

 

Now there are solutions, first is go to the supplier and get the cost of the unit, which by the way will by law have a full g/tee. You can shop around the various makes sold as own label Siegs. Others electronics will fit.

 

There is also the option of just fitting a generic motor control circuit from say EBAY, ex Chinese , rated at up to 30 volts and up to 20 amps or more. These are east to wire in, and simply require an on /off and reversing switch.

The unit is best fitted off the lathe on a lead, with new switches, and the switches on the lathe bypassed.

 

The fitting of these units is easy, but only if you have some electrical experience. Advice can be given here, but not if your a total novice, when it would be best to find a local electrician to help.

 

The advantage of using the generic power controllers is cost, they start at under £10 for a 10amp and should not be much more that £15 for a higher rated one, get the highest rating you can afford.

 

This all assumes that the motor is a DC version, the AC version is different, with usually no speed control and a reversible AC motor, with little or no electronics. Your original supplier should be able to tell you the details, but they can be worked out if they are unhelpful,

[bertiedog]

The other first thing is to find out if it is a C2 C2A or a C3 from China, as each takes it's own board and motor.

By the way if you replace the controller then a new power supply will be needed but they are cheap from Ebay as well.

You can change the motor as well to brushed coreless or brushless AC motors, which use AC controllers. There is a wide choice to fit or add off the lathe. you can also fit a traditional AC reversible single speed motor off the lathe on a belt drive.

Scooter motors will also fit, these are brushed Dc motors, fairly cheap in various ratings.

There are lots of videos on fiting replacement motors etc on You tube. Be careful with descriptions involving US mains, it is different colours! safetyy, and insulation etc, seek advice if novice.

[Izzy]

Point number one, there are two motors, one mains, and one a coreless DC type, so it must be determined which it is first. With the Dc motor it is probable that it is the board at fault. Now if the motor is DC, then yes a charger or battery would run it, but the current is high at over 10 amps.

 

Under no circumstances must the DC motor be put direct on to 240 volt mains, and I would not recommend running the Dc motor on a charger really, as it will be only half wave rectification, and over heat the motor.

 

Now there are solutions, first is go to the supplier and get the cost of the unit, which by the way will by law have a full g/tee. You can shop around the various makes sold as own label Siegs. Others electronics will fit.

 

There is also the option of just fitting a generic motor control circuit from say EBAY, ex Chinese , rated at up to 30 volts and up to 20 amps or more. These are east to wire in, and simply require an on /off and reversing switch.

The unit is best fitted off the lathe on a lead, with new switches, and the switches on the lathe bypassed.

 

The fitting of these units is easy, but only if you have some electrical experience. Advice can be given here, but not if your a total novice, when it would be best to find a local electrician to help.

 

The advantage of using the generic power controllers is cost, they start at under £10 for a 10amp and should not be much more that £15 for a higher rated one, get the highest rating you can afford.

 

This all assumes that the motor is a DC version, the AC version is different, with usually no speed control and a reversible AC motor, with little or no electronics. Your original supplier should be able to tell you the details, but they can be worked out if they are unhelpful,

 

 

The other first thing is to find out if it is a C2 C2A or a C3 from China, as each takes it's own board and motor.

By the way if you replace the controller then a new power supply will be needed but they are cheap from Ebay as well.

You can change the motor as well to brushed coreless or brushless AC motors, which use AC controllers. There is a wide choice to fit or add off the lathe. you can also fit a traditional AC reversible single speed motor off the lathe on a belt drive.

Scooter motors will also fit, these are brushed Dc motors, fairly cheap in various ratings.

There are lots of videos on fiting replacement motors etc on You tube. Be careful with descriptions involving US mains, it is different colours! safetyy, and insulation etc, seek advice if novice.

 

It is a Sieg CO lathe, but uses the same board as the larger C1, which is now discontinued. XMT 2315 is the board code. The motor is a plain brushed DC 230v type according to the ratings label but I will double check.

 

Thanks for the confirmation that trying to use a car battery charger will work but draw high amps. Why one was suggested perhaps since they can supply such ratings I believe. It wasn't to run it for a long time, just to confirm it still worked/hadn't failed. I think going to my local garage might be my best option.

 

I have looked at the possibility of replacing the motor/power/control system  with such as a 24v scooter motor as per the re-motor Unimat thread, but I am trying to consider all the options of keeping it contained and portable in a small size. Having another lathe and mill/drill both with induction motors for nearly 30 years I am concerned that the CO's board has failed so quickly, not something I really expected. But it is a nice little thing to use indoors on the portable workbench. 

 

Izzy

[Grasshopper John]

Well after months of searching I think I've got one that fits.

 

 

 

I bought a Hobbymat MD65 earlier this year, It came with a large selection of collets but no Chuck, I've searched everywhere but a chuck for my lathe appears to be as rare as hens teeth, then I came across a forum ( think it was model engineer ) and someone posted that he had a Pratt Burnerd chuck and it fitted perfectly on his MD65.

 

So a bit more searching and this popped up, an 80mm Pratt Burnerd with internal and external jaws and a set of soft jaws, chuck key and fixing bolts, Allen key, brand new in the box, got it this morning and it fits my backplate lovely. I tried friends chucks but none fitted around the flange on the backplate. In the first pic the chuck is sitting on the backplate a perfect match the fixing bolts all match as well, Result.

 

Happy Christmas to me.

 

Grasshopper J

[dhjgreen]

I like the spring on the chuck key to stop you leaving it in, never seen that before. I remember the strict drilling we had in Ferranti training school in 1967 to never leave the key in at any time.

[tender]

I was recently given one of these from a former work colleague:

 

 

It's a Pultra Micro Lathe and was bolted to a substantial bench with the [Heavy] motor unit/drive pulleys/foot operated clutch mechanism mounted underneath:

 

 

Unfortunately I don't have any room for the bench so I've removed the Lathe and propose using a small DC motor/controller similar to that fitted to my Sieg SX2 Plus milling machine mounted on the back with a belt drive.

 

Can anyone see a potential problem with this proposal?

 

It came with this box of goodies:

 

 

Ray.

[JeffP]

Someone GAVE you that????????

 

The colletts alone are worth ££££'s.

[tender]

Someone GAVE you that????????

 

The colletts alone are worth ££££'s.

Worth spending a few quid on a new motor/controller then?

[jrg1]

Worth spending a few quid on a new motor/controller then?

The Colletts are a huge, valuable asset! 

[M Wright]

Hi, I would keep your Mardrive unit if you can.  The ability to control a lathe with a slippable clutch is a great asset in Instrument  work. It is an asset that unfortunately only is appreciated with experience. It also means you have two hands free for the lathe and you can stop and start without using your hands. Also it extends the life of the motor -it runs at constant power and by pressing the foot pedal the chuck rotates from a creep (ideal for tapping 12/14 BA holes) to full speed ideal for turning up a 2mm scale whistle..The whole Pultra setup especially with the Mardrive unit you have is a Rolls Royce machine. They are amazingly accurate (easily able to work to 1/10000") but note the graduations on the handwheels are usually metric and versatile with the extra parts Pultra made. I think I saw the back toolpost in your collet box  which makes parting off tiny parts a dream.

I have had one of these lathes for a long time.  They are built to last, but before use do check the lubrication system to the bearings in the headstock is clean and working and you have adjusted the bearing correctly. You can obtain copies of the manual still (look on e-bay) They were built for an industrial life, with collets they can safely be run at 2500-3000rpm (NOT WITH CHUCKS) These high speeds being necessay when turning small parts. If you have the hand turning rest in the box you can really exploit the high speed by making gravers and learning to use them. As the guy above said, lucky you!

[bertiedog]

Agree with the other posters, you have a very fine quality lathe which is designed as a bench lathe to use the motor unit underneath or behind the unit.

 

Basically the British Pultra was about the best made lathe for light engineering work ever made. It was based upon the Lorch German pattern lathes designed for watchmaking, clock making and fine instrument work. Lorch obviously were not popular after the first world war and the second, and Pultra came on to the market to supply British industry with a replacement, and even better made.

 

The accuracy is second to none, given good condition bearings, and no major cracks or breaks to the bed. Minor marks and dings do not affect the machine in any way.

 

They were designed for second operation work to great precision, with first heavy work done on an auto turret lathe. But the model engineer is not likely to be able to strain a Pultra except with cast iron work.

 

The collet system was fitted as standard on the nose of the mandrill, with a screw for chucks of various types. The collets are Standard Swiss pattern, and available or can be made on the lathe. The box you have seems a good selection, missing ones can be sourced.

 

All classes or work up to inspection grades and prototypes could be made on a Pultra or they could be set up in a  factory to do a dedicate precision job on a production basis.

 

The MOD ordered thousands in the war, and many ended up sold as surplus, finding there way into light industry and parts manufacture as well as precision clockmaking and instrument making.

 

The first thing is to strop and check, clean, and re-assemble the main bearings, which is a lot easier than it sounds, the nuts are released, and the lot comes out for an inspection. They have Lorch type floating cones in bronze bearings that are adjustable, so if no scoring and the cones are OK, then the bearings last forever, but if worn out they can be replaced with bronze ones made on another lathe.

 

The whole lathe should be be washed in paraffin, and then de-greaser, and re-lubed with suitable single weight engineering or car oils.

 

The guide ways and Gib strips are usually Lorch pattern, and just need cleaning and re-adjusting with the single screw fitted on the end of the slide. Some may have a row of conventional screws to adjust like the Schaublin Swiss lathe.

 

The Pultra is worth a lot of cash, but condition rules the price, a nicely restored one with a new paint job and the vital motor unit, may fetch a premium price. A perfect original, would fetch over a thousand.

 

Please say you will use the Motor unit, it works fine, the motor may be three phase, but convertors are made, or change the motor to a mains one.

 

Belts are made in the heat joint type to suit any set up. Finally do not under any circumstances dispose of or lose any nut or bolt or part from the lathe of motor unit, do not saw up the motor unit or modify it, it is a serious collectors item.

 

Once given a bit of TLC for lathes, this lathe should be able to do the finest standard work any lathe can achieve. Pultra have gone out of business, driven by cheap copies from abroad, but the make was acclaimed to be the best ever made, only disputed by Schaublin and Lorch.

Lorch have alao gone, but Schaublin, the swiss maker is still going and collet spares are made by them.(at dreadful prices).

 

If you have no three jaw for the machine, try to find a Pratt Burnard to fit. There are several large dealers in the UK who sell to model engineers and they can usually source all parts.

 

If you fit a DC motor try to fit off board and do not modify the lathe to fit it, modify the DC  motor unit to suit, as it would affect the value if extra holes are drilled in the base etc.

 

You may not realise it but the original motor unit can be arranged to hang on a wall behind the machine vertically to save space, or be placed under the bench via a long drive belt and extra idler shaft. Pultra even marketed a treadle attachment for war work, where power was limited.

 

I assume that you realise there is lots on the net about Pultra and Lorch etc, history, guides, restoration etc.

 

 

Stephen.

[bertiedog]

Worth spending a few quid on a new motor/controller then?

NO use the Mardrive!!!!!!! and YES it is all worth spending money on..........

[bertiedog]

I note that you said " it was bolted to a substantial bench" ... O.... please say you did not turn that out etc, if it was the Pultra original metal  cabinet stand it is priceless!! They were not cast iron like Schaublin, but were very heavy welded mild steel, and very well made indeed. If it is Pultra then it should have transfers etc on it or a brass plate.

 

Some factories fitted to other benches for production lines. but a cabinet one indicates it was from a toolroom. Only Schaublin stands were better as they cast them and then aged them for up to 10 years in the open weather before machining!!!! Lorch used cast but aged them in ovens. The Pultra was simpler in using sheet steel, but the gauge was heavy and they were stable, and prompt delivery for war purposes was more important at the time!

 

Stephen

[tender]

Many thanks for all the encouraging words.

Looks like I'm going to have to try and rearrange my workshop a bit to try and get the lathe installed with the original Mardrive motor. That might take some doing but sounds like its worth a try and will save me having to buy and fit a new motor/controller. I'm pretty sure the motor is single phase 240vac hence the 13A plug on the end of the cable.

 

Unfortunately the bench isn't an original Pultra but a wooden affair made from 4"x2", a substantial 1 1/2" thick solid hardwood top and a couple of draws. No fear, i didn't chuck it, its in the garage holding up a Adept Hand Shaping machine and heavy vice (also donated).

 

Ordered a copy of a Pultra manual off eBay so hopefully will be able to get it striped down, serviced, setup and back in action for the new year.

[Dave John]

Interesting thread, lots of good advice. I keep looking at lathes, but keep coming back to the conclusion that my old Perris Moldelmaker is all I actually need. The Tray on which it sits was "borrowed" from a works canteen back in the days when works had canteens and cooked yard square bakewell tarts and the like. 

 

 

 

 

 

 

 

[bertiedog]

Pity no bench, but nice to find a mains plug. Do not hope for too much from the manuals, they are really a spare parts listing, but the Lathe is a logical design and should be easy to service, bar stuck bolts or nuts, and screws that have broken down tapped holes!

 

I may be seeming to prempt your knowledge on lathes but check the wear to the bed at the head end, it should not be serious, and check the tail end has not been used as an anvil. If you find gouge marks into the iron base do not worry at all, it is ones that leave a upstanding lip that should be flattened by scraping away any excess.

 

The main check is to flush out any abrasive as it might have been used as a polisher in a factory, not a major worry as the bearings can be replaced, and the iron bed is tough.

 

Stephen

[bertiedog]

The Perris is not a bad lathe, it's design was the basis for the Cowell type etc. and all it's basic operations are there in miniature form from a Myford. It is also a size that makes making extras for it easier than bigger lathes. It can do milling as well, and I doubt that a Seig etc would be any better, only convenience in fittings etc. As long as the bearings are not totally shot, the lathe can even make new ones.

[M Wright]

Hi, I see you have had some more very well informed advice about your Pultra. Your Mardrive is the same as mine.  Mardrive were a separate company. They made these progressive clutch units fitted to motors for industrial sewing machines. It looks to be fitted with a single phase Hoover brand motor.  You even have a nice Dewhurst reversing switch (again worth a good price and a well made bit of quality kit)  I would like to see it rewired with modern multicore protected cable and get the whole lot pat tested for earthing before use!  Have you got the foot pedal for the clutch?  It is joined to the motor link arm by  flat chain and /or steel wire , the pulley wheel is to ensure alignment  with the arm of the clutch. There is a lot of helpful information  and loads of photos on www.lathes.co.uk  I look forward to seeing some nicely detailed models coming off your bench in due course.

[jrg1]

The miniature Peatol lathe produces accurate work, and there are plenty around.  My criticism is that it does not have a driven leadscrew for surfacing work-although a computer counter can be added.  For my 4mm scale work, it is quite capable.  Moving up towards model engineering work, I favour the Colchester Student as a compact, versatile, accurate and reliable unit.  I have found that model engineering machine tools are generally quite expensive, and small ex-industrial machines, such as the Colchester can be a far more economical proposition.

[tender]

Hi, I see you have had some more very well informed advice about your Pultra. Your Mardrive is the same as mine.  Mardrive were a separate company. They made these progressive clutch units fitted to motors for industrial sewing machines. It looks to be fitted with a single phase Hoover brand motor.  You even have a nice Dewhurst reversing switch (again worth a good price and a well made bit of quality kit)  I would like to see it rewired with modern multicore protected cable and get the whole lot pat tested for earthing before use!  Have you got the foot pedal for the clutch?  It is joined to the motor link arm by  flat chain and /or steel wire , the pulley wheel is to ensure alignment  with the arm of the clutch. There is a lot of helpful information  and loads of photos on www.lathes.co.uk  I look forward to seeing some nicely detailed models coming off your bench in due course.

Thanks again for all the advice and the link. I'm sure the foot pedal is in one of the draws of the bench but I don't remember seeing a chain or cable but that shouldn't be to difficult to make up once I've put it all back together.

[Guest Isambarduk]

"I was recently given one of these from a former work colleague:"
 
Good grief!  I thought that I'd had a blessed life but your experience really takes the biscuit!  Do treasure this gift from such a benevolent colleague.
 
I have managed my 7mm modelling perfectly well with a couple of Unimats (one set up as a lathe and the other [which was given to me, to be fair] as a miller); they have been faithful friends but, unlike your machine, they are not things of beauty or to be treasured, particularly.

 

David

[ozzyo]

"I was recently given one of these from a former work colleague:"

 

Good grief!  I thought that I'd had a blessed life but your experience really takes the biscuit!  Do treasure this gift from such a benevolent colleague.

 

I have managed my 7mm modelling perfectly well with a couple of Unimats (one set up as a lathe and the other [which was given to me, to be fair] as a miller); they have been faithful friends but, unlike your machine, they are not things of beauty or to be treasured, particularly.

 

 

 

 

David

 

Hello David,

 

do you have the milling table for the Unimat? I have one that I don't use, drop me a PM.

 

OzzyO.

[Grasshopper John]

Following on from my purchase of the Pratt Burnerd chuck a couple of refinements were required, first was the M5 bolts supplied were too short at 45mm so I ordered some 60mm these did the job but I had to cut about 5mm off.

 

Next the locating holes in the backplate are 7mm ( well about 6.6mm ) so when assembled there was a very tiny amount of movement enough to throw a job off true, so I took a friends advice and made some sleeves out of some scrap aluminium. This was my first job on the lathe first I turned down some 7.8mm bars to the size of the locating holes in the backplate then faced them off and made a center hole and drilled a 4.9mm hole through the middle to accept the M5 bolt then measured width of backplate and cut to length.

 

First two attempts wern't satisfactory but practice makes perfect ( they say ) so here is the final result all three now a nice fit in the backplate and hopefully will take away that little bit of movement I had.

 

 

I am a novice I know but pleased with the result.