Colchester Student Mk1 Won’t Start

[Richard Kirkman 1Participant @richardkirkman1]

Big compressor it is then! (one day)

My belt grinder has a 2hp motor with vfd so I don't think it needs changing to run off air

I'm not too sure what you mean by backsplash plate. My lathe doesn't have one like Phils does.

I received an email back from the man at Danebury electronics.

He said

"Unfortunately we don't keep records dating back that far.

I would replace capacitor values like for like.

My best guess for capacitors if they are unidentifiable are

Run capacitor 60uf 450V

2X start capacitors 80uf 450V.

Broyce relay set to around 275V"

So it looks like the capacitors in there are correct, but they still all need replacing.

But, from what I found on the 80uf capacitors on eBay, they were motor running caps not start ones. So I'm a little confused once again.

[Phil WhitleyParticipant @philwhitley94135]

here ya go Herman!

[Herman van der MerweParticipant @hermanvandermerwe76509]

Thanks @Phil, so I see the side plate is all straight with the last bit into a lip. I have a lot of panel beating ahead of me!

[Herman van der MerweParticipant @hermanvandermerwe76509]

Posted by Richard Kirkman 1 on 29/05/2020 11:39:37:

But, from what I found on the 80uf capacitors on eBay, they were motor running caps not start ones. So I'm a little confused once again.

Just buy the running caps. They are "stronger" than starting capacitors and obviously costs more but will be a lot more stable.

[Herman van der MerweParticipant @hermanvandermerwe76509]

Can you guys please post a picture of your lathe's apron? Not your kitchen one please

We are trying to figure out what apron my funny lathe has and how it works.

[Richard Kirkman 1Participant @richardkirkman1]

I've made a little bit of progress with the traveling steady. Still getting better at painting, but I'm getting there. Sprayed it for the first time today, it gives a much better finish, I'm amazed, even with a wagner fence and decking sprayer. I just wish I had sprayed the primer on with it too! The finish could still do with improvement, but I'll sort it somehow.

I think painting more things at once would be much better, so I might move onto doing a few lathe parts soon. I can feel the tailstock calling to me

Pictures and video of apron

Video Link

[Herman van der MerweParticipant @hermanvandermerwe76509]

Paint work looks good! Keep hacking away at learning how to paint and then you will hit the wall … you will need a quality compressor ..

Thanks for the photos and the video. Seems like my lathe is missing the lockout arm thing. I will double check tomorrow if it maybe is not laying somewhere, but I doubt it.

I see your one gear is as bad as my lathe's! One day when you strip, clean and paint the apron you can take measurements of the lockout arm thing for me.

Thanks again @Richard!

[Herman van der MerweParticipant @hermanvandermerwe76509]

Posted by Richard Kirkman 1 on 30/05/2020 20:30:25:

Morning @Richard. Would it be possible to take some more pictures of the bolt thingy that holds the lockout arm in place?

I found a photo with dimensions on the Colchester groups.io page as below. Would it be possible to get something in the apron from underneath to check the length and possibly the width of the lockout arm against the sketch's dimensions?

[Richard Kirkman 1Participant @richardkirkman1]

More pics here. I don't think the thickness of it matters too much as long as it fits in the slots that are on the lead screw bit. As yours is in pieces i'm sure you can measure the slot and other parts. I can get even more pictures, but I think I've covered most angles that I can get to it

Just to be clear, my apron is shown in the manual that I sent in somewhere. So that's the place to look

i can't get a full measurement but the measurements from the picture seem right to me.

Look carefully at the shaft it's resting on, there's a flat.

I've emailed the company I bought the converter from to ask if they'll pay for the capacitors, but their website is no longer available and their Facebook has shut down. Perhaps they have closed down. Either way I'll get new capacitors.

Herman, is there any requirement to use the same brand, or am I okay to buy these cheaper ones that are unbranded. Surely they're the same? They have all the same codes on, yet they're much cheaper

Cheaper Caps

 

Edited By Richard Kirkman 1 on 01/06/2020 13:07:43

[Herman van der MerweParticipant @hermanvandermerwe76509]

Hi @Richard! Thanks for the detailed photos. These are really helpful!

Re the caps. I think we need to backtrack a bit here. Something does not feel right after I have read your whole thread again.

Your RPC needs to be designed to work with your electrical motor installed. Did you do that or did you simply match the lathe's motor to the RPC's output voltage and kW rating and bought the RPC based on those two parameters?

I brushed up on my RPC knowledge and you will need:

1. Two running caps rated at at least 370VAC or higher

2. One starting cap to start the idler motor rated at at least 250VAC or higher.

3. There must be some form of disconnector to disconnect the starting cap after the idler motor has started. You will need to find this and determine what it is. I can be a relay, a timer, a bimetal heat based switch.

4. Overload protector to protect the RPC if it is still running and the mains power goes down and comes back up again while it is still running. I think the orange box is wired for this but not sure.

The values of the caps will depend on the type of motor you have installed in the lathe. It looks very old, so I doubt if it is a squarel cage or induction motor.

So you will need to post the specification plates of the lathe motor and the idler motor of your RPC for me.

Then you need to let me know the type of disconnector in the RPC and the specifications thereof.

You will also need to make yourself a cuppa of whatever you drink and trace and draw the RPC's wiring as it is in the big blue box at the moment. In other words you will reverse engineer the existing circuit and produce your own wiring diagram which we can then analyse and check for compliance to your needs.

Lastly the best place to buy your caps would be https://www.surpluscenter.com/Electrical/Capacitors/Motor-Run-Capacitors/ and https://www.surpluscenter.com/Electrical/Capacitors/Motor-Start-Capacitors/ (Not that I know the UK that well, but this is a know source for quality equipment at good prices)

Once we know the details of what we have in place we will have to design the cap values around these. I am very rusted on this as I studied and used this many many moons back when the moon was still blue …

[Herman van der MerweParticipant @hermanvandermerwe76509]

Posted by Phil Whitley on 25/05/2020 20:48:02:

Evening all!, well I was right, I haven't got the holes, or the threads, I have two bolting down holes without threads at the headstock end, and one,central, at the tailstock end

The hole that you guys have in the cupboard at the front of the lower shelf is not there on mine! Don't bother with the measuring Herman, it is sitting firmly on a level floor, and it is staying where it is until after I have replaced the spindle bearings and then do the alignment!

Phil

Edited By Phil Whitley on 25/05/2020 20:48:57

@Phil, while I was searching for details about the apron lockout key thinghy I read that your lathe must be fitted with leveling pads. These fit from the bottom of the holes and you adjust the nut on the pad's threaded rod to get the lathe level.

I would recommend you buy machine leveling pad with the ball joint in the top of the pad which allows the threaded rod to enter the lathe exactly perpendicular to the lathe's bottom plate.

[Richard Kirkman 1Participant @richardkirkman1]

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.

[Herman van der MerweParticipant @hermanvandermerwe76509]

Posted by Richard Kirkman 1 on 01/06/2020 21:37:57:

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.

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.

[Richard Kirkman 1Participant @richardkirkman1]

Posted by Herman van der Merwe on 01/06/2020 22:02:23:

Posted by Richard Kirkman 1 on 01/06/2020 21:37:57:

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.

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.

[Herman van der MerweParticipant @hermanvandermerwe76509]

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.

[Richard Kirkman 1Participant @richardkirkman1]

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?

[Herman van der MerweParticipant @hermanvandermerwe76509]

Posted by Richard Kirkman 1 on 01/06/2020 23:12:57:

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

[Phil WhitleyParticipant @philwhitley94135]

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.

[Richard Kirkman 1Participant @richardkirkman1]

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

[Herman van der MerweParticipant @hermanvandermerwe76509]

Posted by Richard Kirkman 1 on 02/06/2020 11:20:37:

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.

[Phil WhitleyParticipant @philwhitley94135]

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

[Herman van der MerweParticipant @hermanvandermerwe76509]

Posted by Phil Whitley on 02/06/2020 21:05:09:

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!

[Richard Kirkman 1Participant @richardkirkman1]

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

[Richard Kirkman 1Participant @richardkirkman1]

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.

[Herman van der MerweParticipant @hermanvandermerwe76509]

Posted by Richard Kirkman 1 on 03/06/2020 15:35:44

VIDEO.

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

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

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