Colchester Student Mk1 Won't Start

The rotary converter is fine for what I'm doing. I do not need to change anything. I just need to replace the capacitors at the same value as was already in there.

I was simply inquiring if there was a difference in buying unbranded capacitors to buying the named and branded ones.

There are no issues with the converter. If you read the manual I put in the thread, which I have reattached, the literature explains it clearly.

Thank you for going into such detail, but I don't think it is necessary as there isn't really a problem that needs solving to that extent.

However I would like to understand what this converter does since I have watched numerous videos on making your own converters, but this seems simpler than those.

With respect I disagree. The RPC is to be matched to the type of motor you are driving. Your lathe's motor is VERY old, so the RPC might need different cap values to what is in it at the moment to be suitable to drive your lathe's motor.

I trust you understand my concerns.

I have changed the motor. I am now using a TECO 2003 3hp three phase motor. So much more modern.

I understand and appreciate your concerns. However i don't see the issue, the literature shows that the converter can run any single motor 5hp or less due to the power compensation circuit which eliminates the need for selecting and deselecting different amounts of capacitors for different motors. So my understanding is that it doesn't need to be suited to the motor, since it adjusts itself and works for a range.

My apologies. I was not aware that you changed the motor. I must have missed this post(s).

In this case, yes buy the two running caps and the one starting cap with values matching the existing. I would simply buy three running caps from the Surplus store.

I have just ordered some caps and female spade connectors, they should be here in the next fortnight or so.

But I still don't see why the motor age makes a difference. What is the difference between 2 three phase motors? Surely they would just work the same? Or do they make motors differently now?

There are so many types of electrical motors that one needs to be very careful in assuming an electrical motors are all the same. It is like eggs. All eggs are eggs, but then you get duck, peacock, snake, crocodile, chicken, ostrich, etc and etc eggs.

Here is a very short list of electrical motor types I took from the internet.

Types of AC Motors

Classification Based On Principle Of Operation:

(a) Synchronous Motors.

1. Plain

2. Super

(b) Asynchronous Motors.

1. Induction Motors:

(a) Squirrel Cage

(b) Slip-Ring (external resistance).

2. Commutator Motors:

(a) Series

(b) Compensated

(c) Shunt

(d) Repulsion

(e) Repulsion-start induction

(f) Repulsion induction

Heck, when I was studying one of my colleagues actually designed and built a very efficient three phase motor using a 220 liter oil drum as a rotor.

So no, three phase motors are not the same. In lathes and textile machines I have seen three phase compensated commutator motors used very often. In pumps, other types. It all depends on what is required from the electrical motor.

Edited By Herman van der Merwe on 02/06/2020 08:00:52

Most motors which we know as "three phase motors" are Asynchronous squirrel cage induction motors, the design of which has changed very little over the years. The use of VFD's has neccesitated the introduction of new winding tecniques and higher quality varnishes and encapsulation to make the windings suitable for high frequency operation, but they will still run perfectly on normal 3 phase. Basically, the "pony" motor on the phase convertor and the motor on the lathe are both Asyncronous squirrel cage induction motors.

Well, that is interesting.

I found the picture that I took of my apron in the manual, might help a little if you haven't looked it up

Also, I have been speaking to the man who I bought the converter from. He seems very knowledgeable about these converters and what he's saying is very interesting. I'll let you know if anything comes of it

Thanks for the reminder of that specific parts list even though it is with the wheel on the LH side whereas mine is on the RH side. I will check the dimensions of the arm after I made a plywood template/prototype.

Let me know what the seller of your RPC has to say. Sounds interesting.

@Phil, yes you are correct, but in my line of work I have learned never to assume and only make designs calculations on actual facts. The old motor @Richard had in his machine did not look like an induction type motor so that made me worry a bit as the RPC caps values would have had to be adjusted a bit for the old motor.

Herman " but in my line of work " You have piqued my interest, you obviously have good in depth working knowledge of the electrical industry, What do you (or did you) do as a job? I was trained as an Electrical engineer, doing maintenance, repair and installation in many different types of industrial settings, most of which unfortunately no longer exist!

Phil.

Edited By Phil Whitley on 02/06/2020 21:05:45

I am a qualified Professional Engineer and I specialised in the fields of Geotechnical Engineering as well as Water and Waster water purification. The last field requiring the transfer of major scoops of electrical energy to mechanical energy. Most of what I know in the field of electrical energy is self taught so as to enable me to design RO plants and anaerobic digestion plants.

Yeah, you know, as you say so truthfully, time changes too many things! And sadly we need to unlearn many things as these become obsolete. The first control room of a dam I helped built as a trainee Engineer spanned 1500m2 over two storeys. Today the same function is done by a PLC system on a DIN rail in a cabinet.

When I was about 10 years old I read the autobiography of Tesla. That book really inspired me and made me start thinking out of the box ... alas, so many things remain undiscovered. Heck, someone in the first day class of Electrical Engineering 101 stood up the other day and started to answer the Prof's question as to what electricity is. Stuttering turned to silence and all he got out was: "Sorry professor, I have now forgotten!" The professor's reply? "There stands the only one in the world who knew what electricity is and now he has forgotten!"

I am thinking of retiring as I actually was on my way to New Zealand when the virus made me and the wife miss our first set of flights and then a few days later the second set. I sold my business over here in SA and with NZ now having major economical problems future work seems most unlikely.

Phil, when I am in the UK again I will most definitely come and drink a Guinness with you!

Sorry for hijacking your thread Richard!

No apology needed Herman, It's all interesting to hear. Although no talk of Guinness please, you're making me thirsty and the pubs are still closed!

I've just had a little play. I think the capacitors aren't causing the lighting issue, I think its the vibration of the lathe shaking a connection loose. Have a look

VIDEO.

Yes, The lathe doesn't quite knock itself that hard. But it does vibrate. What is this caused by?

A bad connection perhaps? Contacts in need of cleaning somewhere?

I'll still be replacing the caps when the new ones arrive and the spade connector

Back to some actual fixing

I think it was just caused by the entire box not being secured properly. A few of the threads are stripped so it's hard for me to get the box all the way in, however when I managed it worked nicely. I also cleaned the 3 prongs that the power goes through, and the holes they go in. The box bit was bent out of shape too, so I have beaten it back into shape so it now fits nicely.

I managed to get two of the screws in and they held well enough to make it work nicely!

VIDEO

I'll drill and tap them M8 and buy some bolts, which I will turn down to the correct dimensions and put a slot-head on. This way I can get the exact fixings I want. I believe they're currently quarter inch, but I dont have any imperial taps, so m8 will do.

Also, while I'm working on the box area, I'll give everything a good clean and take a look at the starter switch. It's always had quite a bit of slop to it, so I'm going to sort that out by making a sleeve to go inside it. If I leave it wobbly then It's only going to keep wearing until it breaks fully. The only issue is, I'll need a longer bolt to fit inside for the way I want to do it, so I need to figure out what thread it is.

I'll also have a look at the forward and reverse switch as this seems to be loose too.

Most likely the V-belts are not of equal length. Have you done the chalk test on the belts?

I have simply filled mine by using black powder and superglue. First I coated all the inside faces of the hole with the superglue and let it dry. Gave it a very light rub down with some steel wool. Then gave it another coat of superglue.

This way the superglue seals the bakelite.

I then filled the hole with the black powder and dropped the superglue onto the powder. So the hole is filled and hardened now. I still need to drill and sleeve the handle.

I meant what is the electrical issue caused by, but I've figured that out now.

The belts are almost definitely different lengths or not running right as they make a lot of noise and sound like they're hitting off each other. What is this chalk test?

I managed to sort out the excessive wobbling by using a much longer bolt, it works much better now

Wobble before

Wobble after

So it's now much more satisfying to turn, and doesn't feel like I'm about to break something.

These are only finishing touches but they're the feel of the machine, everything I touch when I use it. So I think it's important for it to feel nice so I enjoy using it more.

I also did the same for the reverse forward switch

direction switch before

And then it had no movement after. all the play was from the actual knob spinning, not the shaft spinning.

The last handle that Is loose is the main on/off lever. There is a lot of slop in this and it makes it feel loose and less tactile to use. The only trouble is, it's actually worn.

Herman, after seeing your future shiny handle I think I need to polish a few of mine. Perhaps just a brushed finish

I cleaned up the face of the switch box too. There must be a more elegant way to write reverse and forward onto it

Interestingly, there is the original lathe colour paint underneath the grey. This means that the switch is original, or at least was put on when the lathe was painted before.

This is the handle, it will be brightened up. The rod is held in by a blind pin. Any suggestions as to how I can get it out without drilling out the pin? Drilling is last resort, but I think it might be inevitable.

I'll get the bolts tomorrow for the cabinet things

Posted by Richard Kirkman 1 on 03/06/2020 21:51:38:

This is the handle, it will be brightened up. The rod is held in by a blind pin. Any suggestions as to how I can get it out without drilling out the pin? Drilling is last resort, but I think it might be inevitable.

I'll get the bolts tomorrow for the cabinet things

Have you checked that it cannot be punched through and out the other side? Remove some paint on the rear surface and check. If not then screw a self tapping screw into the hole of the pin and pull it out with a slide hammer.

Yes, I checked the other side thoroughly, but I did not take a picture. There's definitely not a through-hole for the pin to be knocked out.

You need a matched set of v-belts. If you do not have such you need to replace the belts with Nu-T link belts. I only run Nu-T Link belts on all my machines.

Chalk test - http://www.lathes.co.uk/colchester/page2.html