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In need of some advice repairing a lathe

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James Sanchez09/10/2018 16:08:17
2 forum posts

Hello, Im new to the forum and was hoping that someone with more experience than I could offer some knowledge regarding a second hand lathe I have purchased.

It is an Optimum Opti d 140x250 Vario which was sold as not working with an electrical fault, but was very cheap so I thought it was worth a punt. I didnt take a picture before taking it apart but its physically in good condition, just a little mild rust here and there and and everything's still very smooth.

it was manufactured in 2002, which I think means it was made in Germany as i'd read that production was moved to China in 2003. It looks similar to the modern Optimum Opti d 140x250 Vario, but there are slight differences with the controls placement an the width of the gearing cover, the lathe branded Quantum D140 x 250 Vario is identical though.

So after taking it apart I have discovered that the control board and the motor are both burnt out and that I now need to replace them, yesterday I contacted Optimum and a few Chinese company's which had the motor listed on their website, but so far had no reply.

I have a hunch that if/when they do get back there are going to be fairly expensive parts, I am willing to spend what money it requires to function well, but I would really like to spend as little as possible, so would be happy to source alternative cheaper parts.. I would love to know what my options are, what would you do?

The motors model number is 83ZYT004 with an 8mm shaft, specs can be seen here,

**LINK**

Ive been looking for a replacement motor online and so far haven't come across anything that really seems similar, I wouldn't like to go any lower than the 450w that was in the lathe..I don't know if it is important that it matches the 6000rpm or other specs, and don't know where I should really be looking, any help and suggestions would be very appreciated. The room available for a motor 8.8 x 9.8 x 15.2cm

And also with the control board, are there any cheap good alternatives? I have had a glance at something like this (link below) but dont know if this would be subtitle, of so I would lose the main on/off switch but if it meant saving £150 or more I think id be willing to sacrifice it.

**LINK**

If you would like any photos please do ask, and I really appreciate any replys.

James

Neil Wyatt09/10/2018 19:19:13
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15010 forum posts
638 photos
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HI James,

I'd look at getting a 3-phase 450/500W motor and an inverter.

This will give you a pretty much bullet proof solution.

You may need to put an intermediate pulley/shaft to replace the existing motor.

Neil

Martin of Wick09/10/2018 20:07:58
37 forum posts
2 photos

James,

I think the controller in the link is only suitable for low voltage motors (hence 9 to 60v) and you would also need an appropriate power supply for the input side.

As stated, you have a choice to go AC with a 3P motor & VFD or scout around for a Suitable DC motor that may approximately fit

The AC solution will cost about £100 including VFD sourcing the cheapest you can find, but as a starter for 10 try these DC options

Motor

**LINK**

controller

**LINK**

The motor spec is conservative and from my measurement is the rating at about 180v. The controller chucks out about 230v at max, and the speed is close to 5000 no load at that voltage. holds speeds well down to approx. 15% of full duty.

The motor seems quite happy to run at 230v, but have not run it for hours so not quite sure if it would get very hot at high loads.

For that little money, you cant really go wrong, it will get you going while you search for a reasonably priced beefier DC motor, and unless you get something pulling more than 7 amps (allowing for the fact that Chinese amps and watts are worth about half of the imperial) you will be able to use the controller. And at that price you might as well buy a spare controller too!

Cheap as chips & semi crap, but works for me!

Martin

Martin of Wick09/10/2018 20:25:20
37 forum posts
2 photos

Also,

Just seen this......

jMAAOSwn6Rbn9s2">https://www.ebay.co.uk/itm/500W-220V-DC-Treadmill-Motor-DIY-Project-Electric-Variable-speed/253877628028?hash=item3b1c492c7c:gjMAAOSwn6Rbn9s2

bit pricy, but if you are a power hog it would suit. you will need to check size and speed, but most are usually in the range 4 to 6k unloaded

for the record, I have no connection with this vendor - just satisfied with the motors I have purchased.

James Sanchez10/10/2018 21:05:28
2 forum posts

Thanks for the replys.

Yes Neil I had thought about that, but would really like to keep the motor contained within the lathe if possible, probably silly as its purely for aesthetic reasons..just seems a shame for such a small lathe to have the motor outside..especially when there is room there for one.

Hadn't looked at treadmill motors, thanks martin, they seem perfect. Your last link there I would happily pay, to be honst, I had been expecting to pay a lot more. Do you think that motor would be more than enough yea, even at lower rpm? Seen other stronger ones on eBay for a similer price.. im guessing they would be an option to if they fit, if I was to get the inverter separately?

And sorry one more thing im unsure off..probably a ridiculous question, but I really am clueless when it come to electronics, it frustrates me greatly. Would I be able to wire in the main on/off switch and/or the forward/stop/reverse switch that are on the lathe, between the plug/inverter or inverter/motor? Or would I need to get an inverter with a forward/reverse or on/off built in, should I want it?

Thanks again, James

Martin of Wick11/10/2018 16:10:19
37 forum posts
2 photos

James,

To put it in context, I use the 220W motor to drive a Peatol and it is more than enough (1/3 HP on a 2.5 in lathe!).

From what I can tell, your lathe is a clone of the ubiquitous Chinese Mini Lathe (I have one of these too)

If it were for me, a 500W motor should be more than adequate for the CML (looking at the motor picture, it is actually rated at 3.6A which if true means the maxpower may be 30% higher  Without having one on the bench, I think it is as good as anything currently supplied with this class of lathe.

Check the motor size to be sure it will fit in the tight space

Check the no load RPM x 0.85 or so against the ratios on the drive train to be sure it gives you the desired range of speeds.

The controller supplied is OK but simple, you can get better ones - did see some being sold as plain boards with options for ramp and torque and electronic reverse for about £20, but cant find these anymore, or you can fork out £100+ for an American made KB controller (but from what I have read, these aren't much more reliable than bog basic controllers from china)

If suitable either get the 500W motor and PWM drive package or a more powerful motor if it will fit and you really think you need it, but beware of over motoring the lathe. To make life simple make sure to get a permanent magnet type brushed motor with a suitable speed range. Find whatever controller suits.

Rip out all of the old electronics from the lathe control box.

Check the remaining switch gear - does the mains on off/e stop switch function and more importantly, does it incorporate a latching servo (ie is of no volt release type)

Secondly, does the rotary switch rev-off-on look butch enough to handle about 10 A and is it at least 3 pole? - you will need to check carefully it can be used in a dual pole dual throw manner by working out the connections with a multimeter (or a battery, bulb and some wire as a simple continuity test)

Because on my CML, all of the switching functions are latched electronically, I suspect the answer is no to both of the above. You then have a choice - If the switchgear is still functional from checking with a multimeter, visual inspection etc use them anyway and devil take the hindmost until they fail or the fuses blow (but remember to always switch everything off after use and check that everything is always off before plugging in) Remember also that you will be wiring the DC motor feed of 240V via the rotary switch so make sure you are content with mounting, isolation, robustness etc)

Alternatively, if in doubt, or unable to make a judgement, go to the usual outlets and get....

**LINK**

and

**LINK**

or search for 10 amp DPDT toggle switch

and because you never know when you might need it, a cheap BIG RED BUTTON type E stop switch, all together new switchgear should cost less than £20

and wire as follows - Estop - NVR on off - controller - DC out to Rotary motor run reverse switch - DC motor

remember this will be a manually switched system, so you will have to remember to avoid casually flipping from forward to reverse without letting the motor stop and also avoid starting with PWM drive set at maximum speed - just to be kind to the motor and drive!

If all that is too daunting, then try UK lathe suppliers that carry spares such as Amadeal, ARC eurotrade and purchase a complete motor and control board set up but you will be looking at well over £200 outlay

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