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Colchester Student Mk1 Won't Start

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SillyOldDuffer08/04/2020 10:27:29
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Posted by Richard Kirkman 1 on 07/04/2020 19:44:24:

Thanks Dave, good to know someone else is still interested...

Have a look at the number of 'reads' you're getting. At the moment this is the forums most read thread on a technical subject.

People aren't commenting because Phil is doing such a good job helping with the electrics and you're not needing help with the mechanics or using the machine yet. Don't be put off by lack of responses.

Expect more reaction when you ask about paint colour, tool-height setting, HSS vs Carbide, toolposts, confirming alignment and run-out etc. The fun starts as soon as the lathe is able to cut metal! (Making that washerwas a good first test - it confirms the motor is delivering power, not just spinning, that the gears and controls are more-or-less sound, no obvious problems with the chuck and headstock bearings, and the saddle and top-slide both behave as expected. No gross mechanical problems emerged. More good news or bad doing more jobs: facing, turning longer rods, screw-cutting, using the tail-stock, taking deep, fast cuts, drilling etc. If all those go well, you can confirm alignment with Rollies Dad and confirm precision and tightness with a DTI.)

Have to say it's looking good. Lathe condition is difficult to assess by eye: a dirty old lathe might actually be in good condition whilst spit and polish examples hide a multitude of sins.

Dave

Dennis WA08/04/2020 10:58:25
76 forum posts
5 photos

Richard...Phil has done a great job in helping you, including emphasing the safety aspects.

I agree with Dave that you have sorted it out as you have progressed and are learning as you go.

I have a 1964 Student Mk 1.5 and have followed the thread with great interest. At no stage could I add anything to what you had got from other folk.

Congratulations on your progress - enjoy using the Student and good luck with your studies.

Dennis

Richard Kirkman 108/04/2020 12:05:01
300 forum posts
740 photos

Dave- Sometimes I think most of those views are mine! Thank you, it's nice to hear some positive feedback after all this. It's probably been 6 months since I got the lathe now, so lots of missed opportunities to make up for. I wouldn't do it any differently since I've learned so much.

Thanks for the rollies dad thing, I haven't seen that before. I do have an indicator, but I need to make a mount for It to go onto the magnetic base. Perhaps today's project

Dennis- Thanks, good to hear from someone else! I hope you've learned something about your lathe too!

Howard Lewis08/04/2020 12:35:17
3544 forum posts
2 photos

It will be time well spent to make a Centre Height Gauge. It can sit on the Cross Slide, it has a machined flat surface, or on the flat bedway.

There are various ways of adjusting it to exact centre height, from simple to complicated, depending on what equipment is available.. It can be either "suck and see" to use of slip gauges and vernier height gauges

The objective is being able to set tools on the centre line so that they cut properly.

If you want to see a picture of the one that I use, and how to make one of your own, PM me with an E mail address, and I'll send pictures and instructions..

By now, I have made about six, using different methods, for different lathes..

Howard

Phil Whitley08/04/2020 13:37:33
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1251 forum posts
147 photos

Hi Richard,

It is not certain that a phase to earth would damage the phase convertor, but having a "leg down" would put a large unequal load on it, and it is not worth the risk! all exposed wiring should have a primary insulation to keep the electric pixies seperate and inside the wires, and a secondary insulation to protect the primary insulation from mechanical damage. Flexible conduit, and bushings where cables pass through metal fulfills this essential safety requirement. Do you remember the wiring on my Rapidor machine hacksaw? Well, Don't do it like that!!

The not starting sometimes, mine does that as well, I put it down to dirty contacts in the C&D switch, OR moving the handle down too quickly, and bypassing the intermediate position of the C&D switch before the contactor has pulled in fully, and closed the holding in contacts. try moving it a bit more slowly and I think the problem will dissapear.

the reason you do not hear a massive clunk like you do with mine is that the modern contactors are virtially silent, and will probably last 10 to 20 years, whereas the one on mine is big, numb, and has a large surface area of armature and contacts, which slams metal to metal in a very noisy fashion, and will last, with a bit of maintenance, forever!

Phil.

Edited By Phil Whitley on 08/04/2020 13:38:45

Richard Kirkman 108/04/2020 16:56:34
300 forum posts
740 photos

Thanks Phil, very informative. There are quite a lot of loose wire in there. I'm not sure how l'll be able to cover them all

The lathe looks like it has space for feet on the machine through some threaded holes. Im not sure if anyone else has seen This Old Tonys video on lathe leveling, but he has a student mk1.5 and it has 6 feet to allow for leveling?

I made a mount for my indicator today, although I'm not sure it's on the right kind of stand, it's works for me

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I used a weird insert I found on arc euro trade. It said it was for non ferrous metals so I thought I'd give it a try, it did a good job I think

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I turned around 250 thou end for the indicator to sit on, then turned the rest to fit in the holder nicely

I img_20200408_143928.jpg

Drilled the end out to 3.3mm for a m4 thread. It was nice to finally get to use my taps. Although they were too small to use a spring center, it went in very well by eye

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I had a play with my has parting off tool, ground it to how it was suggested, then I played around looking at the center height. It was a long way off, too high. I used the flat bar trick thing. I did try to grind it down a bit but it was taking too long. And since it was such a small part I decided to use my carbide parting off tool which was under center so I could shim it to the right height. It worked like a dream, 120rpm or so, hand fed, very slowly, with plenty of oil. Only aluminum so not too hard, but still good practice

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When I parted off yesterday I used the other end of the tool which was lower, but I didn't check the height of that, so I don't know if it was or wasn't on center. Guessing it wasn't since it went so badly yesterday.

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It fits! A nice little project

Now I'll be able to use my 4 jaw when it dries. I put another coat of paint on it today. The first had only just dried as I put it on so thickly, and it pooled at the bottom. So just a thin coat today!

Phil Whitley08/04/2020 18:52:15
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1251 forum posts
147 photos

Hi Richard, You dont have to cover all the wire, only where it is exposeed, it is fine when it is inside an enclosure, like inside the switch or the control panel, but it must be protected when it is in the open, or where it goes through any holes in metalwork to prevent vibration wearing away the sheath and exposing bare copper. the metal or plastic flexible conduit fulfills this purpose.

I dont like the idea of feet on a lathe, although many people do use them. If you check the manual, my manual says it has levelling screws ( mine hasnt, or any threaded holes) and it does detail using them to get the bed straight. See what your manual says. There is little point in putting feet on the colchester, it is the bed of the lathe that needs to be level, or more accurately, straight (without twist) and leveling the cabinet will not neccasarily achieve this. If you look at my video of the rebuild on my lathe, you will see a slide of the refitting of the bed to the cabinet, and you will notice that it is only fitted to the cabinet with three bolts, which have sealing washers on them to stop coolant leaking in to the base. I think it would be a lot easier to level (straighten) the bed at this point, instead of applying twist to the cabinet, and hoping that this twists the bed in the right manner. However, it may be that given the small amount of twist required, doing the adjustment between the bed and the cabinet will result in too much bed movement, I don't know, because I am not going to do mine untill I have fitted the new bearings.

What I would do for now is to get the lathe sitting flat on the floor, with the cabinet well supported all round, you can use sheet metal shims to stop any rock if the floor has any low spots, , and then do a test cut to see if there is taper, and which direction it needs twisting in. There are loads of good videos on youtube showing you how to do this. Using a level, you need to level across the bed at each end using a precision engineers level, and the difference in the readings is the amount of twist you have. All things considered, it is more important to see how much taper the lathe turns in use, and correct as much as you can, without becomnig too obsessed with ultimate accuracy. "Rollies dads method" looks good to me, but bear in mind that I have never done this to my Colchester at all (although I fully intend to in the fullnes of time)l, and it has always made the parts I wanted, to an accuracy that was easily sufficient for what I was building or modifying. Have a look at "home made lathe machine" on you tube to see what this guy makes with his home built machine tools.

That coolant pump is very noisy, sounds like bad bearings, but easy to strip and replace them, cheap too compared to what a new one costs!

Phil

Edited By Phil Whitley on 08/04/2020 18:58:52

Phil Whitley08/04/2020 20:00:47
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1251 forum posts
147 photos

Hi Richard, checked the manual again, and although it gives the position of the supposed jacking bolts. the details it gives for alignment are for the headstock and tailstock, not for eliminating twist on the bed.. I will be at the workshop in the next couple of days, not sure when, but I will have a look for jacking bolts (or threaded holes) in the positions marked, although I am sure I have looked before, and there are none, if there is, and I missed them, it would make it a lot easier to straighten the bed by twisting the cabinet as the front one is at the left end and the rear one at the right end, so definitely positioned to induce twist, and from the diagram, it looks like they are inside the motor housing,and inside the cupboard|!

Richard Kirkman 108/04/2020 21:32:08
300 forum posts
740 photos

It's not just the twist, it's also raising the lathe since I'm taller than average, it's a little low. I don't want to be crouching over to use it. Accuracy isn't quite it either. Obviously I've got plenty of time so I'd like the machine as well as possible, but that had limits. I'm not sure if the garage floor is level as well

I'll strip down the coolant pump once I'm done with the apron, another rabbit hole

When I've been playing around with threading, the lever doesn't always want to disengage fully, so I thought I'd try to take it to pieces so I can get in to clean. Also, I wanted to look at why my main carriage hand wheel moved in and out, which is very anoying when turning. All has become clear!

img_20200408_190218.jpg

So the issue is, I can't remove the apron completely without taking the SC gear box off. So I thought I would just take the top of the carriage off and clean in from the top. So I started to take it to pieces. The holding part at the back came off first, then I unscrewed all the bolts holding the top on. This unattached the apron, but the top was still attached with a part underneath. I couldn't remove it since I didn't have access. The only way was to slide it across then lift it off once the gap bed was removed.

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First time I've taken the gap bed out. I'm very tempted to paint it orange while it's out😀

I have no idea how this would be disassembled on a straight bed lathe, possible the long way round

This then let me take the top off, so I have access to all the gears. Very dirty inside as expected, I'm just wanting to get all the gunk removed and have it cleaned up

img_20200408_195128.jpg

img_20200408_195118.jpg

Some very thick gunk in there. Anyway, I'll get on with a proper clean tomorrow. It won't be perfect, but it'll be better than before.

I also got a look in behind the shaft that the wheel goes on, there's a circlip holding the shaft in place, but there's a space of about a quarter of an inch that's unoccupied. Looking in the manual, I'd say there should be a spacer in there to keep it from moving back and forth like mine does

img_20200408_195137.jpg

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Dennis WA08/04/2020 22:32:34
76 forum posts
5 photos

Richard,

I am sure you have thought about this, but do not get paint on any surface of the gap bed that sits on, or is adjacent to, the main lathe bed. To preserve the accuracy of the machine when reinstalling the gap bed it must be clean and go in the exact same position.

My Student stands on a concrete floor with some shim under one corner to get it firm and level. I have no problems with accuracy of the finished product.

If you want to raise your student you could use heavy steel channel across each end. My Myford Super 7 ( which is on a factory steel cabinet with tray) is raised like this. I also have no problems with its accuracy.

I have a high precision level which helped to ensure the lathe beds were not twisted. I machined test bars to confirm the lathes cut the same dimension near the chuck and at the end of the bars near the tailstock.

Good to see you are able to use the Student.

Dennis

Dennis WA08/04/2020 22:34:09
76 forum posts
5 photos

Duplicate post removed

Edited By Dennis WA on 08/04/2020 22:36:40

Richard Kirkman 108/04/2020 22:45:00
300 forum posts
740 photos

Thanks Dennis, of course I will not be painting any of the contract surfaces. I probably won't even paint it right now as if I'm painting, I need to paint the whole thing!

What sort of approx size shims did you use. Lxwxh? Obviously it depends how level and flat the floor is, but I'm just interested

I'll have a look at getting a good quality precision level just to test things

Dennis WA09/04/2020 10:07:02
76 forum posts
5 photos

Richard

I used a piece of coated steel approximately 150x80x1.6 mm that was to hand.

Dennis

Phil Whitley09/04/2020 11:48:11
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1251 forum posts
147 photos

Hi Richard,

to remove the apron, you remove the lead screw and feed drive shaft first, they disconnect from the SC box under the sc box top cover. So, with the saddle still on, you disconnect the lead screw and feed shaft from the SC box, remove the support at the tailstock end (you might have to do this first, to get enough clearance to get the leadscrew and feed shaft disconnected), slide the leadscrew and shaft out of the apron, remove the apron, and then remove the saddle retainers front and rear under the saddle, and remove the saddle. You could still do this if you support the apron on some wood blocks, do not let the weight of the apron hang on the leadscrew and feed shaft, they may bend!!

Phil

Edited By Phil Whitley on 09/04/2020 12:04:16

Richard Kirkman 109/04/2020 11:56:02
300 forum posts
740 photos

Thanks Dennis

I don't really fancy taking it that far apart right now, so I'll just clean what I can access from here. But I will have to put it back together to make a new spacer, then take it apart again to fit it! I should probably go support the apron...

The weather was really nice yesterday, so I left the tractol out in the sun. It actually became much thinner than before, so it was much easier to paint and left an alright finish. I still need to do a few more coats.

 

Also, Does anyone know exactly what size key I need for an mt3 jacobs chuck? I don't seem to have the right size and managed to size it up wrong already. The model options on their website don't make much sense to me. It's a no34 chuck, I'll see if I can find anything

Looking at my order history, I just got confused and got a k32 key when I should have got a k3.

Yep, ignore that, I'm being stupid and not doing enough research

Edited By Richard Kirkman 1 on 09/04/2020 12:04:39

Edited By Richard Kirkman 1 on 09/04/2020 12:10:16

Edited By Richard Kirkman 1 on 09/04/2020 12:14:20

Richard Kirkman 109/04/2020 20:25:57
300 forum posts
740 photos

I did some cleaning today. Got everything ready to go back together. I need to measure up the size of the new spacer I need to make. Needs 5/8ths bore, then o can measure the thickness when it's all back together. I need to remove as much of the slop as possible since it's causing uneven wear on the gears.

All the oiler holes were bunged up with gunk, so a good clean should have helped them a lot!

I cleaned the gap bed thoroughly, but I don't think I'll be painting it this time around. Maybe next time

img_20200409_161532.jpg

img_20200409_164543.jpg

Also, I think I'm going to get some 100x100 box section steel, 5mm wall so I can raise the lathe. It's just too low and it hurts after extended use. I may as well make it comfortable.

I've also found a very cheap precision level, so that will come in handy

Edited By Richard Kirkman 1 on 09/04/2020 20:30:07

Richard Kirkman 109/04/2020 21:17:04
300 forum posts
740 photos

Wheel video

In the video you can see where it's already been worn unevenly

Phil Whitley10/04/2020 11:26:45
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1251 forum posts
147 photos

Don't worry too much about the wear Richard, it is not a "precision" control. Fit a spacer to take up the play, clean out the oil holes into the bushes, and call it done!

Phil

Richard Kirkman 110/04/2020 14:33:16
300 forum posts
740 photos

I wasn't worried about the precision or the wear. It's just anoying having the wheel move in and out.

I put it all together, measured what I needed, then made the spacer. I had a play with speeds and feeds. It would be nice if I'd remembered to bring my machinery's handbook back from uni with me

Parting off is going much smoother now, so thank you for your tips. Although I am still using the carbide one, I will get back to the hss one since it's thicker and will be better for heavier work

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Parting off

I'll take it to pieces again and reassemble with the spacer this afternoon. I hope it fits😀

Howard Lewis10/04/2020 15:20:00
3544 forum posts
2 photos

More progress! "Every day, in every way, I get better and better"

You are up and running; making things to repair things!

My problem with parting off is that the face is never as good as is obtained facing with a normal tool, which always makes an additional op for. me. So the tendency is to part off slightly over length and then face back to the required thickness, or even, most unusually for me; to make it look nice!.

Keep up the good work.

Howard

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