Colchester Lathe Headstock rebuild - Warning - scary gearbox monster lurking inside... Pic heavy.
Turbo Mini Forums

Thought I'd share this with you guys, not strictly "mini" related, but it does have SC CR gears LOL!

A little backwards, but this is the lathe that is now back in operation all leveled and sitting pretty:

Over here, it is known as a Clausing colchester 15", but I and the most of us know this as the Triumph 2000. I have a soft-spot for the colly's, partially because it, and the Harrison M300 was what I spent all my time on at college, but also because it is a very compact (short) lathe, with a large 7.5hp motor, metric threading without having to unbolt gears, and a HUGE spindle-hole. Loads of them also had taper turning (as this one does). They aren't really great lathes like a DSG or Hardinge, but for "home use", especially in a limited footprint, they are pretty hard to beat.

I got this cheap with a known "clutch issue" and was sure it was the clutch rollers given the early serial number (they used needle bearings, later changed to solid rollers), which is actually a very easy fix, *IF* this is the only thing wrong.
Unfortunately, it looked a lot worse when I opened it up, so it's been a long time in repairing... I've actually sold two other lathes while having this one, I bought it five years ago, and have rebuilt the headstock and re-commissioned it in the past few months.

Unfortunately, there was more than just the clutch rollers, hence it took a few months on and off...
I also had another issue that is all too common with these lathes; the input sheave (pulley) coming loose, something I thought was due to it only having one woodruff key fitted (yes, really), but realised later that it is just a crappy design! This is a pic I borrowed off a unit recently selling on eBay, mine looked very similar to this:



Fortunately, the shaft itself was made something like 1.08" diameter, so these are easy to repair by (tig) welding up the keyways, and turning the shaft down to 1".
This was what the finished repair was like:

I used a taper-lock bushing to mount the pulley in place on the shaft, the SD-1 size worked perfectly. I am running a temporary sheave right now, because the factory sheave didn't have enough stock to machine for the taper-lock, so will soon machine another taper-lock sheave down to use as a "hub" for the original pulley as aftermarket pulleys have the belts spaced too far apart...

But the biggest nastiness was in the headstock itself.
Despite these lathes running a pressure-fed lube system from a tank in the base under the headstock, they never fitted a filter in there, and the suction for the pump was approx 10mm above the bottom of the tank, so all the junk was easily "re-distributed"...

This is a pic I (again) borrowed off eBay, but is pretty typical for what they look like inside:



These pics are from the inside of mine after a very brief cleanup with WD40 to get the worst of the crap off..:



Below you can see the clutch rollers that collapsed. Also note the bearing race on the top-right; all dark and dirty instead of clean and shiny. Because one of the rollers had probably failed before the others failed and rendered it inoperative, the clutch fork was also beyond repair due the the clutch sleeve being canted over at an angle.




This pic below shows the other major failure: The compound (cluster) gear on the middle-left sits on a metal-backed bushing that had failed and dissolved. This had left the shaft getting chewed up - this gear is the final High/low drive the the spindle. The gear had been used this way for a while (must have made a heck of a noise) and had chewed up the previously machine-ground shaft.
I took the shaft to an engine re-conditioner, who put it on a crank grinder and took the min off until it cleaned up (12 thou). I sourced a good used gear, pulled out the bushings, then machined two oilite bushings to replace the standard bushings, loctited them into place, then bored out the ID of the two on the Bridgeport leaving 1.5 thou of running clearance - a little on the high side, but will have a good opportunity to get oil into there



To rebuild this, I basically stripped the whole headstock down, including the spindle. Every bearing as replaced with SKF bearings after trawling ebay for NOS bearings, luckily the spindle bearings looked great, so these went back together as they were. Every geartooth was checked, and cleaned, occasionally de-burred and polished (parts for these are sooo expensive, so is a question of make-do instead of replace unless it is "worn"...

Lots, and lots, and lots of cleaning followed, as well as changing all the seals and o-rings.
I got all the parts from GPS, who were REALLY cheap, and very knowledgeable. www.gpsengineering.co.uk

All said and done, these are the finished article:












I also added in a filter so the headstock will only get clean oil (see above image):



I haven't painted the outside of the headstock, because that would leave everything else looking even more dirty! I personally prefer machines that look "used" so you don't need to worry about oil stains (its a colly so it leaks oil like everything else made in the UK in the 70's) LOL

Lots of little things still to do, but it is operational - AND (for a colly) very quiet, even at 2000 rpm!!!
There are no vibrations like the "made-in-taiwan" colchester 15" at my workplace has. All feeds, speed and threading work, haven't checked the taper-turning yet, but sure it'll be just fine.


I scored an Aloris CXA tool post and holders at an auction a while ago, and have collected 15", 12", 8" faceplates, 10" six-jaw chuck, 4-jaw, centres, MT4 drills and have been collecting other various tooling over the past 10 years, so this will likely be covered in swarf in a short space of time!


TD

Edited by TurboDave16V on 14th Oct, 2014.

Very nice, will be on the look out for one of these myself when i get a bigger shop. A long bed version is pretty much the ultimate lathe compromise imo

i did the tvr clutched automatic conversion on one of these in the 90's really nice lathe .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Is the Mini leaking Dave?

Yep, stripped sump plug... It's coming out soon.

Red Bull Soapbox or Flugtag?........

huh?

Intrigued by the wooden box with wheels lol

ah, yes...
That thing is in my way no matter where I put it...

It contains a racetrack for the local cub scouts. I offered to make a box to keep it in as that'll make it easier to store, and that was interpreted as "I'll store it" LOL
Hopefully will have it to someone else soon!
It makes an OK (if a little low) workbench however!

Edited by TurboDave16V on 13th Oct, 2014.

Good job on the lathe by the way

You have far too many tools...

superb! dave

Excellent stuff

hopefully im not on my own saying im a little bit lost with all those gears

Yes i moved to the darkside

Instagram @jdm_brett

Stop playing with your own stuff, and let's get some cad drawings from you .

Also please can we have some photos of your hot wife,???,

Team www.sheepspeed.com Racing

Dave,
I was just googling repairs for my large which is also a Colchester triumph identical to yours. The reverse rollers ended up in bottom of the gearbox...

Did you go for solid replacements and were they from the place you mentioned? I was tempted to make some but by the time I've bought the reamers etc...

Is the clutch assembly easy to get out? Looking in the top I'm guessing it comes out through the casing after removing the drive pulley and bearing?

Other than that mines pretty good. I like the filter mod though. I've got a Beaver Mk2 mill which is a little bigger than the Bridgeport.

Hey Iain,
Good to hear you are still around!

All the rollers after 1980 ish were solid as far as I can tell. They were about 45 quid each from GPS IIRC. I just changed them all out for solids.

For the clutch, ease of removal depends on the year. The later ones with the electric brake (no brake pedal) are easier to remove than the earlier ones with the brake pedal, but it's much of a muchness - you are getting into the depths of the gearbox and more stuff may turn up amiss...

If you google triumph 2000 there is a site where the guy tells about how he bought one for a few hundred quid - that site will have both manuals for download. The cross-sections of the shaft will show what needs to be done.
Basically:
Pull off top cover and rear clutch access panel.
Remove belts off input sheave (pulley) and remove sheave.
Remove the fastener at the "chuck end" of the clutch shaft (this is where it is easy or difficult depending on the year)...
Remove the three bolts holding the bearing retainer on behind the sheave, and use the screws to jack it out.
If you have disconnected the shaft, it will all slide out. The clutches can now be rolled forwards (pulling the shift fork too) and then out of the hole.
On the bench, set them vertically, then lift one end off, and rest (upside down to how you started) adjacent. Remove the plates one at a time, transfering from one side to the other, inspecting and checking they are ok. If all is good with them, you can just wind in the collars as needed and replace the roller assemblies.
Assembly is the reverse of removal - lol
Remov

Yeah still lurk from time to time but no mini for a while now. Have a steam roller of all things at the minute
Mines the earlier one so I'll see about the chuck side of the clutch assembly then. Yeah mine must be pre 1980 as its all on the roller versions. It's a pretty clean machine, came out of a fire station for £150! Didn't meet HSE requirements and could only be sold for scrap...
I have the normal manual for it so have a lot of the info. Always good to hear if there are any tricks.
I'll get stuck in today then can order the bits while I'm away at work (2 week rig trip) ready for when I get home. A Coventry die head is also on the shopping list as I've got a lot of bolts and studs to make. I know where there is a ward capstan lathe up for sale as well that is tempting. Can never have too many tools!
Hope all is well with you
Iain

Dave, just a quick query as I ran out of time today trying to look at it.

I've got the pulley off, bearing out and am looking at getting the clutch assembly out. At the brake end I've removed the 4 radial dowels so it can slide out. I'm assuming I have to pull the brake assembly out from the "headstock" end, then remove the "brake drum" before I can slide it out towards the drive pulley end.

Is there enough movement to lift it out the fork?

Is down on your lever forward or reverse? Mines forward. Could be I have 2 phases different to how it should be hence why my forward (which should be reverse) works well. I suspect worn plates.

Iain,

I think I may have given you some bum info... I am wondering if you can slacken off the clutches sufficiently to actually replace the rollers. Try this before going any further....

I'll have to look when I'm home again. I suspect one side of worn plates anyway so removing isn't the end of the world. Good to get this kind of thing out the way then can use it for what it's meant for. I think I've found the taper turning attachment amongst the spares too