Mini lathe Motor issues HELP!

Thread Starter

Jack.fan

Joined Nov 21, 2020
3
Hi guys have two problems I need help with. I bought a mini lathe from eBay with its original motor and an extra motor. I’d like to get both working but they each have their own problems.

Firstly the original motor remains on when the switch is in off position. I opened the plastic hatch to see the capacitor (I think) and the diode. One of the diode legs was bridging the switch terminals shorting it and keeping it on so I figured out the problem. When I bent the diode back down however it broke off leaving one leg sheared and unable to be reused. The diode label was mostly rubbed out but I could just about make out enough to find the datasheet: https://elektronik-lavpris.dk/files/sup0/126620DSdioderBBC.pdf it’s a DS1.8 18A. I can’t find any exact replacements online. Can anyone recommend a suitable alternative?

Now, the second motors label is also slightly worn out (very old mini lathe and motors) and the wiring has come out of all the terminals. Can someone help me figure out what goes where? I will attach all relevant photos for the original and additional motor. I will be very grateful if anyone can help me!! For reference I live in the UK with 240v at 50hz coming through the outlets. Thank you:)
 

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Dodgydave

Joined Jun 22, 2012
9,837
Hi, Welcome to the forum,,the diode is a 7amp 1800V working, I would use a P600 from Vishay, there are other higher voltage rated diodes but these are metal tab types, .

https://uk.rs-online.com/mobile/amp...dfCP_hRWY7Nx02pkv6kaAjHcEALw_wcB&gclsrc=aw.ds

Is there a plate on the motor for model and make number? These have two windings , one goes across the mains and the other has the capacitor in series with it.
 
Last edited:

jpanhalt

Joined Jan 18, 2008
10,913
First of all, you give very little information about your "ebay" lathe. Did you buy a lathe or a motor? That is by far the most important part of your purchase. Is it junk? Or, is it worth fixing?

If it is worth fixing, consider a DC motor with speed controller. Re-purpose the other motors for fans.

Edit: By the way, welcome to AAC.
 

Thread Starter

Jack.fan

Joined Nov 21, 2020
3
Hi, Welcome to the forum,,the diode is a 7amp 1800V working, I would use a P600 from Vishay, there are other higher voltage rated diodes but these are metal tab types, .

https://uk.rs-online.com/mobile/amp/p/rectifier-diodes-schottky-diodes/6391790/?cm_mmc=UK-PLA-DS3A-_-google-_-PLA_UK_EN_Semiconductors_MOB_Whoop-_-Rectifier+Diodes+&+Schottky+Diodes_Whoop-_-6391790&matchtype=&aud-827186183686:pla-340510830467&gclid=Cj0KCQiAkuP9BRCkARIsAKGLE8Xf-e-UAffAAxwY3XYq8by46PP7_ab2aBX8dfCP_hRWY7Nx02pkv6kaAjHcEALw_wcB&gclsrc=aw.ds

Is there a plate on the motor for model and make number? These have two windings , one goes across the mains and the other has the capacitor in series with it.
hi thank you for your reply! I’ll check that diode out now and attach some photos of the other motors label. :)
 

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Thread Starter

Jack.fan

Joined Nov 21, 2020
3
First of all, you give very little information about your "ebay" lathe. Did you buy a lathe or a motor? That is by far the most important part of your purchase. Is it junk? Or, is it worth fixing?

If it is worth fixing, consider a DC motor with speed controller. Re-purpose the other motors for fans.

Edit: By the way, welcome to AAC.
Hi, it is a unimat 3 lathe with some lovely attachments and yeah it’s in great condition, just the motor needs a bit of care. I’d certainly buy a new dc motor for it in the future however I would first like to get this one fixed as it is original and has all the fixings for attaching to the lathe incorporated into it. Not to mention it will look much better when it’s all repainted.
And thanks for having me! :)
 

jpanhalt

Joined Jan 18, 2008
10,913
I inherited a pristine Unimat from my father. It is still in its original wooden box. It has the milling attachment. It cannot turn a tread, and down feed for the mill is crude. But, it can do simple facing and turning to a specific diameter. Speed control was added by a triac (aka light dimmer). Later, I added a small Prazi to my collection. It does have power feed and can turn a thread:
1606000576886.png
The first thing I did to the Prazi was convert to DC, and I was able to thread with it. The Unimate is basically a crude jeweler's lathe. I stand by my earlier comment. If you want good speed control, convert to DC. But, it is still useful as original. The original motor is a "universal" AC/DC motor. With DC control, you will have much better control of speed. KB makes inexpensive (eBay) that will work with it.
 
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