Murad Cadet Restoration Project

[XedParticipant @xed]

Thanks!

Yep, the Paragon paints can be brushed or sprayed – I thought about spraying but don't really have the space or compressor to go down that road.

The levers do look to be held onto the shafts with pins but no amount of tapping with a punch would make them budge no matter which end I tried, so I've parked that as a problem for Future Me.

[noel shelleyParticipant @noelshelley55608]

Check continuity on the 2 wires to the centrifugal switch OK ? check also red to black – note the reading ! Then white to white again note reading. 1 to 3 is a dead short and something is not right with 4,5,6. All the right wires are there but the orderis odd. Check from the red wire to find the other end, that will be the start windings ! there should be continuity between the other 2. That will give you the 4 wires you need. The insulation needs sleeving it is in poor condition. Till next time. Noel.

[HopperParticipant @hopper]

Best gasket making method ever!

The old girl is starting to look very nice in her new livery.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Xed on 02/04/2022 11:58:53:

… first up puzzling out the motor:

…

The measured value of the capacitor (380 nanofarads) is probably wrong, so either a mistook or the capacitor is faulty.

The circuit looks like a Capacitor-Start, Induction Run motor, and I'd expect the capacitor to be much larger, perhaps 150-ish microfarads.

Did the motor start OK before being stripped down? If so, likely 380nF is an irrelevant mistake. However, if 380nF was measured correctly and the motor didn't start, then time to find a replacement. Hopefully the capacitor is labelled with the correct value – it varies depending on the design of a particular motor.

Buying a replacement capacitor shouldn't be a problem once the value is known. Common spare, because they're the least reliable part of a single-phase motors.

The motor's internals look very mucky. Although appearances are deceptive and it might be fine, I recommend an insulation test – damp dirt murders windings! Apart from paying for it, replacing the motor shouldn't be difficult, but if it's necessary installing a 3-phase motor with VFD is a worthwhile improvement: less vibration, more torque, and speed-control.

Would a motor expert comment please?

Dave

[Mike HurleyParticipant @mikehurley60381]

100% agree with Dave's comments – well worth considering a VFD setup if you can afford it! With spending so much time & effort in this restoration, and wanting to end up with a useful functioning piece of kit it's a no-brainer. Also, you may have to do a few minor mods to fit one (cable routing, motor mounts etc) so better to look into it at this stage rather than when its all back together.

Fitted mine 3 months ago, would never look back to the old single phase job.

regards

Mike

[egaParticipant @ega]

How will a VFD fit in with the standard Cadet switching arrangement?

[RedsetterParticipant @redsetter]

Why would you want or need a VFD anyway?

This is a gear-head lathe which gives a good range of easily changeable speeds.

And it has a single phase motor, which is not designed for use with a VFD.

Nuff sed.

[XedParticipant @xed]

I won't rule out a VFD down the line, but it's a substantial chunk of change – and as others have said there's a good selection of gears so I'll stick to a regular AC motor for the time being

I am keeping an eye out if a suitable replacement comes up at the right price, but will happily use the Hoover if I can get it running reliably again (The lathe was disassembled when I got it and I suspect it last ran many years ago). If nothing else it's proving a great learning experience for how these things go together.

I did some more poking around and the capacitor which I initially thought was unmarked turned out to have a label. I also decided to stick a coat of paint on as it was already disassembled so might as well.

Naturally, it was glued to the motor label side down. It had also stubbornly bonded to it's little foam bumper.

A lot of patience with a scalpel and a bit of photoshop lead to this – would I be right in thinking that's a rating of 80-110uF?

I also spent some time with the multimeter checking the cables – the centrifugal switch opens and closes as it should when pressed. The only resistance readings I could get were the following:

Red(1) to White(4) – 13Ω

Black(2) to White(3) – 4Ω

No other combination seemed to be connected.

[Chris GunnParticipant @chrisgunn36534]

As Dave said the internals of the motor are mucky, this is because the motor is not totally enclosed and has vents in the end plates which suck in the muck and swarf. I would swap it out for a new TEFC motor, 1ph if you want to retain the existing reversing switch, of a 3ph one if you go down the VFD route.

Chris Gunn

[Ex contributorParticipant @mgnbuk]

Why would you want or need a VFD anyway?

This is a gear-head lathe which gives a good range of easily changeable speeds.

And it has a single phase motor, which is not designed for use with a VFD.

Nuff sed.

A replacement 3 phase motor will run more smoothly than a single phase motor, but will require something to drive it from a single phase supply – usually a VFD these days rather than a static or rotary converter.

The VFD can be set up to provide a fixed 50Hz – it is not a requirement to vary the output frequency & this is how I choose to run my 3 phase Myford from a single phase supply. Even with a fixed output frequency a VFD can be programmed to give a soft start & stop so easier on the gearbox, plus a 3 phase motor will be totally enclosed so no manky windings due to cooling slots like that poor Hoover.

So many advantages to going for a 3 phase motor & VFD combination.

Nigel B.

[Dave WoottonParticipant @davewootton]

While I would agree that VFD's are great thingsand I have fitted them to almost everything in the workshop,but if you just want to get the motor running and try the machine out for a while, I've cleaned up old motors in the past and used them successfully, mainly out of economic necessity ! The capacitors are cheap to buy and as long as it's all effectively earthed you shouldn't turn into the human torch when you switch it on. Worth cleaning out the crud in the windings carefully with a vacuum, and testing the resistance of the motor coils to earth.

I'm sure there will be moral outrage at this suggestion and before anyone questions my sanity I am a qualified HV engineer. The reason for suggesting trying the machine out for a while on the existing motor if you can is to find out if you like using it. I once spent a lot of time rebuilding a Smallpiece Cromwell lathe, which has an odd control arrangement, only to find I hated using it, this after replacing the aged Ward- Leonard variable speed drive with a new motor and VFD at great expense.

Dave

[SillyOldDufferModerator @sillyoldduffer]

Posted by Redsetter on 03/04/2022 10:33:22:

Why would you want or need a VFD anyway?

This is a gear-head lathe which gives a good range of easily changeable speeds.

And it has a single phase motor, which is not designed for use with a VFD.

Nuff sed.

Not 'nuff sed', because an important detail has been missed. The discussion is what to do if the existing motor is a dud: we know it's filthy inside and the capacitor is probably a goner. Maybe the windings and centrifugal switch are OK, maybe not.

I wouldn't rush to replace a working single-phase motor with 3-phase+VFD. However, the option is well worth considering whenever a deceased single-phase motor must be replaced.

Single-phase motors aren't the best choice of power for a machine tool. Satisfactory rather than good performers, their main advantage is they work off ordinary domestic single-phase power. Otherwise they don't like stop-start operation, vibrate, have low starting torque, can't be speed controlled, are relatively low efficiency and a tad unreliable.

In the age of electronics, DC motors, 3-phase, and Brushless Motors are all better alternatives to single-phase on a machine tool. Brushless have the edge over 3-phase, and DC motors lose points because brushes are a weakness. At the moment 3-phase+VFD probably offer best-value for money, but Brushless is gaining ground, notably because they're available cheaply as a motor, power supply and controller assembly for industrial sewing machines.

A good reason for replacing a dead single-phase motor with like-for-like is to avoid rewiring. Rewiring might not matter because the Murad is being completely rebuilt.

Dave

[XedParticipant @xed]

Just a brief update – the headstock is painted and back on the lathe (the selector arms I'll revisit when I get the other parts done). I drained the old oil and refilled with some ISO32 to pretty much the same level.

Lovely and shiny. A little work on the information plate with some brasso followed by some black paint and clearcoat really brought it up.

That's the biggest and heaviest bits largely done now, currently on the bench I have the covers, guards and the saddle, cross-slide and compound for painting which should be done in the next few days. At which point it'll start looking more and more like a lathe again!

Thanks for reminding me about those sewing machine motor kits Dave, that might be an option to go with if the hoover motor is knackered or lacks oomph. I have read that they can stop pretty abruptly, my only concern is if I'd be risking any of the headstock gearing with one of them.

Now just to wait for paint to dry!

[XedParticipant @xed]

I've put the hours in over the last couple of days and got the guards and slides painted up and reassembled. Here's a quick look at the saddle:

The saddle underside, you can see the gear on the crossfeed shaft for the power feed option. Sadly, I don't think mine has this.

Adjustment to the saddle is made by a tapered block that sits on the far side of the saddle to remove any play. Coming from the minilathe, and it's system of jack screws this is a revelation.

There's a hole for a threading dial at the far end – I'll have to poke around the leadscrew and see if there's anything compatible that can be got (or 3D printed in a pinch)

Painted parts assembled and it's starting to really look like a lathe again. Different chucks will be an option for the future, but I'll have to make the plates for them – as near as I can tell the spindle nose thread is 1 7/8" *TPI Whitworth, so doubtful there's anything off the shelf if I'm feeling lazy.

[XedParticipant @xed]

Currently waiting for the paint to dry on the apron, here are a couple of reference photos from before:

I've also been tackling the tailstock disassembly today:

Thought I could get away with a good rub down and paint. Sadly not!

There are two tapered blocks on the bottom of the tailstock that fit it snugly to the ways, a fixed block and an adjustable.

Cracking the bottom plate off and yeah… the rust has got in.

A full disassembly later and all the parts are gently marinating in a soup of Evaporust for 24 hours. It can damage paintwork but as I'm repainting anyway I might as well.

And that's pretty much where I'm up to!

[XedParticipant @xed]

As my lathe didn't come with a threading dial, I thought that would make an interesting side project – luckily it turns out someone has modelled a functioning 3D printed version for a South Bend that turns out to be compatible!

South Bend 9C Threading Dial

I printed out the gear just to make sure it would mesh with the leadscrew properly and checked the measurements to the mounting hole on the saddle.

Decided to go with a resin print to get a nice finish on the body, in hindsight this might have been an error as I think it warped slightly in curing. If I was doing another I'd probably stick with a filament based process, or at least only resin print the body.

Supports removed and print cured, ready to be primed and painted.

And everything installed around an 8mm brass rod to mount the dial and gear through the body! Everything meshes and moves as it should. I went with my initial FDM printed gear in the end as it seemed to mesh a bit better. Whether it lasts the long haul is anyone's guess but it'll definitely do for now.

[XedParticipant @xed]

And this is where things stand today – the mechanical side of things is largely there. There are a few nice-to-haves that I can work on slowly like replacing the slide handles that are flaking sharp pieces of chrome into your fingers and getting the slides adjusted.

[Roderick JenkinsParticipant @roderickjenkins93242]

Nice job. A useful solid looking lathe

Rod

[Dave WoottonParticipant @davewootton]

Excellent job, a really worthwhile project with a very useful end result. Thanks for posting I've followed this with great interest, as a result I gave evaporust a try and am most impressed with it, always something new to learn.

Dave

[HopperParticipant @hopper]

Useful looking indeed. With those looong carriage extensions behind the saddle, and the tapered gibs, if the bed is in good nick it should be dead steady in use.

Nice work with the thread chaser dial too. Very innovative. A whole new way of restoration.

[XedParticipant @xed]

Thanks for the kind words everyone! It's been a lot of fun documenting this and hopefully will help out anyone else who comes across one of these. I've been in touch with Tony from lathes.co.uk and will send him lots of high res images when it's done for the site.

With the mechanicals mostly done, it was on to the electrics and there was a Decision:

The bang for buck on the brushless sewing machine motor kits just seemed to good to pass up, so I've shelved the old Hoover motor for a rainy day. The deathdapter was naturally binned immediately.

The pedal lever the kit comes with operates by a hall effect sensor that looks to be powered by 5V from the control box. I think the eventual plan will be to replace the pedal lever with a little board the wires up to the original switch – even if it can't reverse the motor by itself it would be fun to have the controls back on there.

And the part number for the sensor itself.

While I was at it, I had a look in the control unit and documented the board.

Overcautious? Maybe – but I do feel better for having the OHCRAP button. It's a 2NC switch with live and neutral going through it that will cut all power when pressed. I wired the earth straight through and the lathe itself is earthed through the motor. I might run an extra earthing wire from the stand back into this box as insurance.

[XedParticipant @xed]

Of course now I needed to physically mount the motor, so ordered in a big chunk of 10mm thick aluminium to make an adapter plate. After double checking with the original mount, I found I'd screwed up by assuming the mounting holes would be in a uniform position – definitely not! I ended up transfer punching through the old plate and drilling everything out to 8mm to get a little extra clearance.

And there it is, a 1HP brushless DC sewing machine motor that is surprisingly grunty.

Mounted in position – I was very surprised that the 50mm pulley it came with fit the original belt pretty well. I do have to keep the guard off with where the positioning of the motor has landed, but I'm thinking of going for a linked belt and adjusting to fit the guard that way. The other thing on the list is making a busing for the original 45mm(ish) pulley from the Hoover motor to make sure it's properly matched to the headstock pulley.

Now we come to the most annoying part – I bought a nice 250-100 toolpost from Warco to go on the Murad and… it didn't fit. The tools would bottom out before reaching the centreline, so I raided the minilathe for its smaller 250-000 cousin and that's working like a champ.

As a little bonus, I did tweet a little video tour before I got the toolpost on:

**LINK**

 

It's already done it's first actual task as well – I turned down the end of the halfnut lever and threaded it M8, then matched that in the boss attached to the shaft. I swear that thing has fallen out for the last time.

Edited By Xed on 15/04/2022 21:18:43

[XedParticipant @xed]

I was able to knock out a few smaller jobs for the lathe over the long weekend, here's what I got up to:

I made a new plate to mount the toolpost to, as the original solution was sitting lower than the lip of the slot causing the toolpost to foul the cast iron.

I also sanded, varnished and painted the tool rack that came with the lathe, and gave the set of collets that came with it a good derusting. Now I just need to work out where to put it.

I also went hunting for the 0.9mm of backlash in the cross slide, so thought I might as well do an exploded view of the cross slide and compound components. (If a kind mod could turn this portrait, that would be lovely )

I'm not sure if it's 60 years of wear, or people trying to force the cross slide when everything was rusted up, but I'm pretty sure the nut is the source of the problem.

I can't tell if it's screwed or pinned – there are no obvious screw heads on the top of the slide, and I didn't want to start using precision violence on it as I've only just got the thing back together. Another issue to dive into some other time.

Also forgot that I hadn't documented the threading chart in this thread, so here you go

[BazParticipant @baz89810]

Wow what an excellent range of threads 2.5 tpi to 96 tpi.

[Ady1Participant @ady1]

Great stuff. Well done you.

[Author]

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