Colchester Student Mk1 Won’t Start

[Phil WhitleyParticipant @philwhitley94135]

the relay K2 can be seen arcing in time with the rattle from K1, I would suggest the rectifier is failing, allowing intermittent DC to K2 and causing the fault we see in the videos.

[Phil WhitleyParticipant @philwhitley94135]

Or possibly C7 or R7? the fact that the PC 40 does this with the lathe disconnected is pretty damning! 3 phase motors will not start or run on 2 windings, when there is a "leg off" they just growl and sometimes turn very slowly.

[Richard Kirkman 1Participant @richardkirkman1]

Phil, to answer your question from a few messages ago, I have not replaced the contact i found in the bottom of the box. The lathe has been wired around that contact so it no longer needs it to turn on. I had my electronics friend look at it. The contactor must have broken so they wired around it, it was the other part of the contactor for all of the microswitches, so that's also why the yellow wire is not connected through the limit switch or to the circuit board.

As far as the use of vfds go, Initially i though i was dealing with a 3hp motor, so a phase converter was going to be much cheaper than a vfd, however now i know its only 1.5, a vfd would only be around £130.

But, I would have to rewire the lathe and i'd much prefer to keep it as close to original as possible.

I have a 2hp vfd wired up to a 3 phase motor for my belt grinder. Also, the motor for the lathe is original. I'm not sure it can be wired up for 230v or not, as vfds, as far as i know, do not produce 440v.

I would use the vfd, but only if its wired to where the plug for the lathe goes, which wouldn't work as I think the vfds need to be attached directly to the motor.

I have a 32 amp plug, so the pc60 seems like the more suitable option to me, as then i'll be able to use it with future machinery too, unlike a vfd where i'll need to buy one for each machine

[Phil WhitleyParticipant @philwhitley94135]

Hi Richard,

You can get VFD's with 415v out but they are expensive. With a std VFD you would, as you say, have to rewire the motor in Delta, and connect straight to the motor, and it looks from your pic of the motor connections that the star point is inside the motor, you could try to test between the incoming blacks and the spare terminal on the connector block, as it is just possible that the star point is connected underneath the spare terminal, but it is a long shot. I think the PC40 should run the lathe easily, theoretically, the PC 20 should run it. I have detailed above how the PC40 works, and what is wrong with it, but we have seen from your videos that it WILL run the motor at full speed, but the starting is slow, and that is a fault on the phase convertor.

Back to the lathe contactor, if the missing contact has been bridged, the lathe must be starting on the other two contacts, the C&D switch cannot start the lathe without a contactor of sorts, as it needs to switch the three phases on simutaneously and seperately. I will look again at the pics of the lathe contactor and get back to you. Must go and cook Isobels tea!!

Phil

Edited By Phil Whitley on 16/12/2019 18:59:46

[mal webberParticipant @malwebber91786]

Posted by Phil Whitley on 16/12/2019 10:43:01:

Thanks Mal, thats interesting, possibly shows up how they fail when they do, although you would expect it to deliver its rated output reliably, but then again, it is probably made in Italy, like much of the machine mart electricals, which means some is good, and some not. I have a Clarke single phase mig from machine mart, and made in Italy, bought in the eighties, and still welding well after much use and abuse, it has had a couple of repairs, but I certainly have no complaints, and I am working on a SIP italian welder /battery charger, which is still going strong, and is suprisingly well built too!

Just a thought, did it rattle like this from new, or did it start rattling when it began going faulty?

Phil

Edited By Phil Whitley on 16/12/2019 10:47:00

Phil no it did not rattle when new only the one clunk [ from the pc 40 as well as the clunk from the lathe ] and it ran well used it like this for years and then it got slower on starting to the point that I had to give the chunk a helping turn to get it running but when it was running it did not seem any less powerful.

Now the pc60 also gives one clunk on starting in any gear hi or low same with the mill, the pc 60 has three switches 1,,1.5 and 3 hp the lathe will start and run good on the 1 and 1.5 switches but when all three are on the lathes motor seems to hum more when running .

Richard if you want me to take a vid on trying to run of the pc40 and then on the pc 60 i can or will try if that helps.

Mal.

[Richard Kirkman 1Participant @richardkirkman1]

Posted by mal webber on 17/12/2019 00:38:00:

Posted by Phil Whitley on 16/12/2019 10:43:01:

Thanks Mal, thats interesting, possibly shows up how they fail when they do, although you would expect it to deliver its rated output reliably, but then again, it is probably made in Italy, like much of the machine mart electricals, which means some is good, and some not. I have a Clarke single phase mig from machine mart, and made in Italy, bought in the eighties, and still welding well after much use and abuse, it has had a couple of repairs, but I certainly have no complaints, and I am working on a SIP italian welder /battery charger, which is still going strong, and is suprisingly well built too!

Just a thought, did it rattle like this from new, or did it start rattling when it began going faulty?

Phil

Edited By Phil Whitley on 16/12/2019 10:47:00

Phil no it did not rattle when new only the one clunk [ from the pc 40 as well as the clunk from the lathe ] and it ran well used it like this for years and then it got slower on starting to the point that I had to give the chunk a helping turn to get it running but when it was running it did not seem any less powerful.

Now the pc60 also gives one clunk on starting in any gear hi or low same with the mill, the pc 60 has three switches 1,,1.5 and 3 hp the lathe will start and run good on the 1 and 1.5 switches but when all three are on the lathes motor seems to hum more when running .

Richard if you want me to take a vid on trying to run of the pc40 and then on the pc 60 i can or will try if that helps.

Mal.

Mal, a video would be very helpful for comparison thanks

[not done it yetParticipant @notdoneityet]

This seems to me to be cheaper/lower quality capacitors changing value over time.

Cheapness is not always a good trait and MM do seem to often offer cheaper machine ‘lookalikes’ … sometimes called ‘clones’

”You pays your money and gets what you paid for” may well apply in circumstances like this.

While I do occasionally make purchases from MM, I do tend to be very careful with my selection and often choose a better product from elsewhere.

[Stuart BridgerParticipant @stuartbridger82290]

This may be of interest, It is the technique I use on my Chipmaster for a VFD conversion.
My lathe has the original 1963 motor which cannot be wired for 240V (or at least not without digging into windings for star point). There is some loss of power, but it is fine for hobby use.

**LINK**

[Phil WhitleyParticipant @philwhitley94135]

I doubt it is weak capacitors, if it were, I would think that the start relay would remain in the start position, because the motor speed would not build, and current flow would remain high. Something is switching off k2, and that should only happen when the motor is up to speed and current falls.

Phil

[Richard Kirkman 1Participant @richardkirkman1]

Still waiting on machine mart, no doubt it'll be another couple of weeks, but who knows!

Stuart, thank you, that link was quite an interesting read, I didn't realise you could do that with a VFD.

Not done it yet, yes I do agree, Machine Mart is best to be avoided, however I struggled to find a comparable converter or even a clone of the same product. The only other thing i could find was transwave, their converters seem much higher quality, If you're judging by the price! I'm not keen on spending twice what I paid for the lathe on the converter though. I'm trying to keep this cheap while keeping the machine as original as possible

Once the lathe's up and running, the next problems going to be sorting out the oil leaks from the headstock and gearbox. I don't even remember if i saw any gaskets when I took it apart (definitely one, but they're old)

Phil, I know you recommended that shelving cork with a sticky back for it, but would this stuff be appropriate?

I found someone selling gaskets on ebay for a student made from the same stuff.

Or would it be easier to just buy them instead of making them myself, as i'm not too sure how i'd go about cutting them all to the right shape

la-520699180922&abcId=1139126&merchantid=115678302&gclid=CjwKCAiAluLvBRASEiwAAbX3GXPMyTkzY8vO4NWmD5U24q-qRs-Zm34CKvHOhaY7gysSQqVPIc2x9hoCyNUQAvD_BwE”>Ebay gasket sheet link

Ebay gasket seller

[JuddyParticipant @juddy]

an alternative supplier of clarke products is Site Box **LINK**

they are often cheaper that Machine Mart,

[not done it yetParticipant @notdoneityet]

Well, I have no idea if they need to be thick and compressible – some may even need to be ‘solid’ – and some can act as ‘shims’, so check them out first.

Forty quid for the few gaskets supplied is steep – even if they are of a suitable material. I’ve made hundreds of gaskets over the years. Mostly paper or rigid gasket card. Paper often just needs suitable ball-pein hammers, thicker material may need hole punches. Craft knife and scissors are good tools, as is a photocopier at times.

They are not difficult to make and you can practise on less important parts. Go for it!

[Phil WhitleyParticipant @philwhitley94135]

The only gasket on mine is the quick change box one, there is no gasket on the headstock gearbox lid, and it doesnt leak! The cork gasket material is available on the net and also at any local agricultural engineers, but it can be pricey there. Look for self adhesive cork roll, available in a variety of thicknesses. For the rest, use Hylomar if you can find it, or failing that Hernetite.Unfortunately both of those latter products have been reformulated, so if you can buy old stock, so much the better, as the new stuff is, as usual, piss poor!

Phil

[Richard Kirkman 1Participant @richardkirkman1]

Posted by Phil Whitley on 18/12/2019 15:36:39:

The only gasket on mine is the quick change box one, there is no gasket on the headstock gearbox lid, and it doesnt leak! The cork gasket material is available on the net and also at any local agricultural engineers, but it can be pricey there. Look for self adhesive cork roll, available in a variety of thicknesses. For the rest, use Hylomar if you can find it, or failing that Hernetite.Unfortunately both of those latter products have been reformulated, so if you can buy old stock, so much the better, as the new stuff is, as usual, piss poor!

Phil

There should be gaskets on the main spindle too, near the bearings when you replace them.

[Richard Kirkman 1Participant @richardkirkman1]

Quick progress update

Spoke to man from machine mart, nothing's happened, seems like they've packed up for christmas a week or two early. But, such is life. Even if I do get a refund, sitebox says the pc60 won't be delivered till the 3rd jan, by which i'll be back at uni. So, i'm back to cleaning the lathe. Will be back to try the pc60 after ive finished my exams on the 15th. Unless I can find a better converter on ebay. Saw a transwave 3kw rotary converter go for 260 today, so definitely worth looking out for

I'm going to order some of the gasket material to make my own, I'll use 2mm nitrile rubber as if that's what the man on ebays's charging 40 quid for then it must work. I'm going to measure my current one, then scale the pictures from his ad to make my own templates. The headstock is going to need taking to pieces again to change the gaskets, so i might be able to sort out the gear misalignment issue too

Finally managed to get the toolpost off the lathe, much to my disappointment, realising that it's not going to be able to fit a QCTP as it's proper 4 way tool post with the built in mount. When the woman responds with some pictures of the spare parts lathe I may see if the top slide on her one has a t slot, might be able to swap them over.

Does anyone know what material the coolant tank is made from, when i cleaned that out there's been a bit of corrosion and some really small places have corroded through. I can borrow a friends MIG welder, and I have some experience welding, so will i be able to just fill the gaps so it's nicely water tight? Recommended or unrecommended?

Richard

[not done it yetParticipant @notdoneityet]

I, for one, would never recommend welding on any closed vessel that has had hydrocarbons in it previously – unless proper precautions are undertaken beforehand.

[Richard Kirkman 1Participant @richardkirkman1]

Posted by not done it yet on 22/12/2019 22:39:28:

I, for one, would never recommend welding on any closed vessel that has had hydrocarbons in it previously – unless proper precautions are undertaken beforehand.

I wouldn't call it fully closed, It could be cleaned out fully and could have a hoover in there too for fumes?

However, what precautions or other methods would be suitable?

[Robert Atkinson 2Participant @robertatkinson2]

If using a MIG clean the tank well and then fill it with shield gas to displace vapours and oxygen. Close the filler with a bit of plastic film and an elastic band so any thermally induced pressure increase is vented..

Robert G8RPI

Edited By Robert Atkinson 2 on 23/12/2019 07:21:21

[not done it yetParticipant @notdoneityet]

I don’t think I used the term ‘fully’ and added the proviso re ‘proper precautions’. A tank with just a screwed-off cap would, in my opinion not be in any way termed as an open tank. Your description and proposal was very poorly/sparsely described.

There are too many, out there, that might give full agreement for some operation that is then carried out unsafely by the person who proposed it.

One then might wonder who would be deemed responsible, if injury or death should unfortunately follow that exchange, or after a third party has followed the same glib proposal and advice – clearly provided on an open forum. I don’t intend being blamed for someone else's folly and I stand by my reply. Simple, unrecommended.

[Phil WhitleyParticipant @philwhitley94135]

Calm down chaps! all good safety info is worth listening to, but the coolant tank on a Colchester student is actually the centre base of the lathe, and is accessed by opening an 18" square door underneath the chip tray, no way could anything explode, and very unlikely to catch fire! A good soak in hot soapy water is all that is needed. The coolant tank is steel like the rest of the lathes stand.

 

Richard, those T slot top slides are as rare as hens teeth, and about £300 on ebay, whilst the QCTP is very convenient, a GOOD one is expensive, and by all accounts the cheaper chinesium ones are not much good on bigger machines like the student, Actually it is a bit odd that yours hasn't got a Tslot one, because most gap bed machines came with them as standard, post up a pic of your topslide with the toolpost off if you can. You could forget the T slot and use the existing bolt and modify a QCTP to fit your topslide. I have a spare plain topslide, and one of next years projects may be to cut a T slot into it, but I am not sure if the Tslot topslide has more meat inder the toolpost than the plain one has, will have to have a measure up, and there are more important things to do first!

Edited By Phil Whitley on 23/12/2019 13:48:08

Edited By Phil Whitley on 23/12/2019 13:51:16

[Phil WhitleyParticipant @philwhitley94135]

these are worth watching Richard. he is a bit vague on detail, but I know what he is doing, he gets it working in the second video, and he is running a much bigger motor on a machine with much more starting load than the Student!

[Richard Kirkman 1Participant @richardkirkman1]

Posted by not done it yet on 23/12/2019 08:09:16:

I don’t think I used the term ‘fully’ and added the proviso re ‘proper precautions’. A tank with just a screwed-off cap would, in my opinion not be in any way termed as an open tank. Your description and proposal was very poorly/sparsely described.

There are too many, out there, that might give full agreement for some operation that is then carried out unsafely by the person who proposed it.

One then might wonder who would be deemed responsible, if injury or death should unfortunately follow that exchange, or after a third party has followed the same glib proposal and advice – clearly provided on an open forum. I don’t intend being blamed for someone else's folly and I stand by my reply. Simple, unrecommended.

Apologies, I haven't quite described it properly. By tank, i meant more fish tank, so more like an open box rather than a canister with a cap. I forgot to put pictures on.

As Phil says, there's an 18 inch opening for scale for the pictures.

Phil, the tool post is all back together now, and it was a pain to get to pieces, have to take the top slide all to pieces as well just to get to it. I'll see if i can find any similar pictures online and i'll watch those videos. Got some other jobs to do around the house first! Thanks

Before cleaning, about 1cm of gunk and rust and whatever else was down there

After cleaning and oiled. Holes are small, but would still leak.

[Philip DParticipant @philipd]

When repairing similar on my M300. I got a thin sheet cut to just the right size for the base and got a local faricator to weld it to the base for a drink, rather than attempt to repair a very poor surface.

[Richard Kirkman 1Participant @richardkirkman1]

Posted by Philip D on 23/12/2019 14:37:39:

When repairing similar on my M300. I got a thin sheet cut to just the right size for the base and got a local faricator to weld it to the base for a drink, rather than attempt to repair a very poor surface.

I'll go in and wire brush all the surfaces so they should be clean. It should be less welding for me to just plug the holes than put a sheet in. And I won't need to buy a sheet. The metal looks thick enough already I think

Phil, the tool post mount looks identical to the one in this post. If you haven't seen it, it's a good read for the first part but seems to not be concluded.

Colchester student QCTP

Video was helpful for how and why I would need to convert the static into a rotary, but if my machine will run nicely enough just from the static converter then why bother with it?

Thanks

[Stuart BridgerParticipant @stuartbridger82290]

if the holes are small, what about coating with an Epoxy sealant?

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