Colchester Master 2500 - defective feed

[belu84]

Hello folks,

I've bought a Colchester Master 2500 3 years ago and everything has been working well so far. However, when I was working on the lathe yesterday, I recognized that the feed from right to left doesn't work anymore. Both the lead screw and the feed shaft don't turn. It still works in the opposite direction (if the lever on the top left is switched up).



Today I wanted to have a look into the gearbox, but I have no idea how to open it. All the screws and levers have been removed, but the cover won't come off. It seems like it was glued to the housing.



Does anyone have an idea how to get that cover off and what could be the cause for the defective feed?


Thank you!

Cheers,
B

 

[Tyrone Shoelaces]

It’s a bit since I had one of those apart but I thought the covers were dowelled in position. If you’ve removed all the levers from the front cover it should be able to be eased off. I used to take out all the screws and put a couple of longer screws back in the corner positions so you can ease the cover along them. After that I had a sharpened painters palette knife that I could tap into the joint to split the joint. There could very well a gasket in there so be careful you don’t damage it.

Two rules in the repair game. Don’t break anything and don’t lose anything.

As soon as you can have a quick look inside with a torch ( flashlight in the US ) just to make sure nothing is fouling inside.

Regards Tyrone.

 

[Clive603]

If the gasket is still there it will be nicely stuck. Especially so if its the original. Over the years they go gluey. Presumably the oil eats into them.

Running round the joint line tapping with a hide, rubber or nylon soft faced mallet may help loosen things. Tyrones palette knife is a last resort. Not something I'd admit in public to using! Besides mine is a putty knife.

I presume you've had the top off and peered down to see if the fault is in the direction selection and initial drive mechanism rather than the gearbox proper. Can't see much but maybe enough if you can be creative with lighting. I have a 1/2" diameter LED light on a flexy stick about a foot long with a magnetic base that is very good for such things. £5 or so from the local Discount Crap shop mixed up with the standard display of tools so bad you'd not be seen dead with. Always the one decent thing in such shop if you nose around.

Have you got a copy of the official manual/parts book? Its pretty good from the what goes where perspective but not quite so good at showing where the drive goes. I have pdf's of headstock and gearbox drive trains for the Triumph 2000 and Student 1800 which are essentially the same. Also manuals in pdf for them but not the Master 2500 itself unfortunately. PM me if you'd like me to send something over.

Clive

 

[Tyrone Shoelaces]

If the gasket is still there it will be nicely stuck. Especially so if its the original. Over the years they go gluey. Presumably the oil eats into them.

Running round the joint line tapping with a hide, rubber or nylon soft faced mallet may help loosen things. Tyrones palette knife is a last resort. Not something I'd admit in public to using! Besides mine is a putty knife.

I presume you've had the top off and peered down to see if the fault is in the direction selection and initial drive mechanism rather than the gearbox proper. Can't see much but maybe enough if you can be creative with lighting. I have a 1/2" diameter LED light on a flexy stick about a foot long with a magnetic base that is very good for such things. £5 or so from the local Discount Crap shop mixed up with the standard display of tools so bad you'd not be seen dead with. Always the one decent thing in such shop if you nose around.

Have you got a copy of the official manual/parts book? Its pretty good from the what goes where perspective but not quite so good at showing where the drive goes. I have pdf's of headstock and gearbox drive trains for the Triumph 2000 and Student 1800 which are essentially the same. Also manuals in pdf for them but not the Master 2500 itself unfortunately. PM me if you'd like me to send something over.

Clive

Nothing wrong with my trusty palette knife Clive, it’s served me well over the years. The blade is only about 1/32” thick so you can’t do any damage with it. I just tap it in gently, feeling for any resistance. It’s sharpened to a razor edge.

Regards Tyrone.

 

[john.k]

Do you want the feed reverse?...Isnt that the lever on the bottom LH of the head.......as mentioned ,the feed gearbox is dowelled to the frame ......IIRC,its pretty much the same as a Bantam ,with lots of tiny gears that often suffer severe abuse...............Also.......feed drive out of the head has a shearpin.........never replace it with a roll pin or any HT steel pin......a bit of brazing rod is OK.

 

[john.k]

Id back up a bit there......IIRC the front part of the box bolts to the lathe bed ,and the back part with the shafts etc actually bolts to the front cover,not the lathe frame......if so ,you will have to slide the feed rod out and maybe also the leadscrew......check the manunal.

 

[eKretz]

Yeah there may be fasteners in from the back side of that. John may be correct that you need to remove the feed shaft, lead screw etc. and the whole thing comes out as one unit, then you disassemble from there. I would look behind there as best I could with a small mirror, that one ear on the top right side sure looks like it would have a screw back there. Too bad you don't have the parts book, that would probably show whether that's the case or not.

And I use something similar to Tyrone's palette knife for disassembly. Sometimes there's no other good option. They can be tapped in gently then slid down the joint to break the seal. Mine is very thin and flexible and sharpened with a nice bevel too. If you do any damage or scratching, it's easy enough to dress back down with a file. I do generally try tapping with a soft dead blow hammer as my first approach when something is stuck. (Key word: gently - be judicious with your use of force if you try that).

 

[belu84]

Thank you so much for your answers!

I have the user manual which includes the respective technical drawings on page 47/48:
https://www.making.unsw.edu.au/media/uploads/Colchester Metal Lathe Master 2500_dQeKOzn.pdf

According to the drawings I can't identify anything which prevents the cover to come off. I might use a hot air blower to apply some heat to the gasket.

 

[Tyrone Shoelaces]

Thank you so much for your answers!

I have the user manual which includes the respective technical drawings on page 47/48:
https://www.making.unsw.edu.au/media/uploads/Colchester Metal Lathe Master 2500_dQeKOzn.pdf

According to the drawings I can't identify anything which prevents the cover to come off. I might use a hot air blower to apply some heat to the gasket.

Looking at the drawing the two halves of the feed box are dowelled together.

Regards Tyrone.

 

[AlfaGTA]

By the drawings the feed reverse is in the head stock, not the feed gear box....Shown as part "G" on drawing page 3. of the Parts section.
Your issue seems to be centered on the feed reverse as it works in one direction and not the other.
Big question , if you remove the rear head stock cover , is the gear coming out of the head stock turning when set to forward and reverse? Shown as reference "A" page 12 in the Maintenance section.
If not, your issue is in the head stock, not the quick change gear box.
Cheers Ross

 

[belu84]

Big question , if you remove the rear head stock cover , is the gear coming out of the head stock turning when set to forward and reverse? Shown as reference "A" page 12 in the Maintenance section.
If not, your issue is in the head stock, not the quick change gear box.
Cheers Ross

Yes, the gears that connect the head stock with the gear box move in both directions and in the head stock everything seems to work smoothly, also the switching between forward and reverse. It really seems that the issue is in the gear box. Sometimes the (forward) feed works for a couple of seconds and then stops again.

 

[john.k]

Sounds bad.....if you are lucky ,the gear in mesh will be part engaged ,and skived off on one side.......however ,my experience of fixing school lathes,is there will be either broken(missing) teeth,or the shaft will be bent enough to have teeth ride over ......some of the gears are tiny!and some have only a few teeth (12 or so).......my memory is getting hazy,but I dont recall having much trouble removing the gear box from the bed ....Im pretty sure the feed rod (keyed) slips out the box endwise,and the leadscrew slips out too......maybe slide the gearbox toward the LH end of the machine ....as I said before ,the gearbox is attached to the bed by the front of the box,the rear part with shafts is not attached to the bed directly.

 

[belu84]

Sounds bad.....if you are lucky ,the gear in mesh will be part engaged ,and skived off on one side.......however ,my experience of fixing school lathes,is there will be either broken(missing) teeth,or the shaft will be bent enough to have teeth ride over ......some of the gears are tiny!and some have only a few teeth (12 or so).......my memory is getting hazy,but I dont recall having much trouble removing the gear box from the bed ....Im pretty sure the feed rod (keyed) slips out the box endwise,and the leadscrew slips out too......maybe slide the gearbox toward the LH end of the machine ....as I said before ,the gearbox is attached to the bed by the front of the box,the rear part with shafts is not attached to the bed directly.

There are 3 screws which can be put through holes in the gearbox cover and which connect the gearbox casing with the bed, if I loosen them the whole casing can be moved, but that's actually not what I want. There should be a way to leave the gearbox casing connected to the bed and just take off the cover, which seems to be dowelled to the casing.

I also can't explain myself why it doesn't work anymore from one moment to another, there is no ugly noise of damaged gears etc. which I would expect if they were damaged. And if gears would be damaged in the gearbox, I would expect that both directions weren't working.

 

[eKretz]

You could have a sheared key that catches and holds the gear so power can be transmitted at times, shifts a little and freely spins at others. The gears for opposite directions can have their own separate keys, or perhaps the key is sheared in such a way that it catches better in one direction than the other.

 

[belu84]

You could have a sheared key that catches and holds the gear so power can be transmitted at times, shifts a little and freely spins at others. The gears for opposite directions can have their own separate keys, or perhaps the key is sheared in such a way that it catches better in one direction than the other.

I see, makes sense!

Just checked again, everything seems fine when I turn the chuck by hand without turning on the motor…

 

[belu84]

Problem solved!

I finally managed to remove the cover - the thin knife was a good hint; thank you Tyrone!

Once I had the cover removed I recognized that when turning the chuck, the gear outside the gearbox was turning as well, but the shaft was not.

I was very happy to see that the gears inside the gearbox are still in a very good condition. However, the problem was a broken shear pin as John.k mentioned above.

 

[Tyrone Shoelaces]

Problem solved!

I finally managed to remove the cover - the thin knife was a good hint; thank you Tyrone!

Once I had the cover removed I recognized that when turning the chuck, the gear outside the gearbox was turning as well, but the shaft was not.

I was very happy to see that the gears inside the gearbox are still in a very good condition. However, the problem was a broken shear pin as John.k mentioned above.
View attachment 348000

Well done and thanks for the feed back. Lots of guys come on here with a problem, get plenty of feedback - and you never hear from them again. So nobody knows what worked and what didn’t.

The thing I liked about the palette knife was the steel blade came right through and was sandwiched into the wooden handle. You could tap the end of the handle with your hammer quite safely.

Regards Tyrone.