My new lathe has landed

[RobCox]

Another day, more progress. There are 2 shafts in the headstock which have ball bearings, both of these are a bit noisy. So while I'm trying to sort out what to do about the rear spindle bearing, I pulled both shafts to check the bearing condition. Result - each shaft has a rough and a not so rough bearing. These are the offending items:

Relatively cheap, so I've gone for SKF. They're only getting done once by me. Looking at the spindle locknut, I'm not the first to get my grubby mitts in there, as witnessed by this damage:

Why ding up the hole beats me. I used a length of 1/4" silver steel as a tommy bar, no damage was done. There are a couple of O-ring retained caps covering the bearings on one shaft. These were removed with an improvised slide hammer:

I've also located the missing metal from the rear spindle bearing inner race. There it is:

Pulling those two shafts lets me get in there. Thats all being thoroughly cleaned. I think the two other shaft bearings have been mullered by this debris.

So to the thorny question of a replacement rear bearing. I've got two feelers out trying to obtain a used one. The most unpalatable option is new. A cool £980
If all else fails I'm probably going to fit a slightly smaller OD bearing and a bush. The only thing that makes the bearing unique to Gamet is it has a flange. There are plenty of bearings in 55mm ID x 100mm OD of a quality that will suit my purposes, but without the flange they'll get pulled in by the preload. If I have to, I'll make a bush to take a 55 x 90mm tapered roller bearing. Turned in one setup and parted off concentricity won't be an issue. It will also make no modifications to the lathe spindle or headstock so it could be put back if I have to.

The hardest part is waiting...

 

[Martin Hocking]

Crikey rob that’s one spicy meatball! I thought buying a matched pair of angular contact bearings for the omnimil was expensive!

Interesting (for me at least) to see that it’s a bearing at each end. In my head having a pair of bearings at the front was a Harrison thing and having one at each end was what colchester did.

I’m not up on the timeline but I guess by the time the ‘M’ lathes come along Harrison and Colchester were the same thing….

 

[RobCox]

More progress this week. I carried on clening out the headstock and the spindle. There was a fine film of black rusty looking carp in every nook and cranny. I decided to strip the spindle fully so it could be cleaned. Thats my bearing extractor poking through the camlock holes that was used to press the bearing off. The front bearing appears to be in good shape fortunately.

Whilst the headstock is off, it was time to mount the motor. Once the headstock is back on. the bolts at the front become difficult to get at. First the motor is bolted to the mounting plate. If you ever have to do this, fit this bolt in the slot before mounting the motor. It's impossible afterwards:

I used some new anti vibration bushes to attach the motor to the plate:

A couple of bits of wood to support it in the right place, and it gets bolted to the back of the bed. The adjuster screws have to be fitted to the bed first. There are holes in the headstock to clear them where they poke above the ways:

This then gets wired up as the top of the motor box can't be got at once the headstock is on:

The headstock got primed and at least 2 coats of enamel, more in some places where the paint got the runs. The various bearing caps got tarted up too.

Once dry, time to get this off the floor and back where it belongs:

Then all the new bearings got fitted. I made a complete pigs ear of fitting these, having done it I know what I should have done, but in the end it all went together and runs very nicely. The bearings no longer drown out the noise of the selector forks dragging on the sides of the sliding gears. Finally, out came the rear bearing outer race. I've sourced a new one - I say new, new to me but used. Still f*****g expensive but a fraction of the cost of a new one. Just waiting for it to turn up.

 

[RobCox]

My next job is the quick change gearbox. I was hoping to simply wash it out with paraffin and scrub it clean. The best laid plans etc etc:

The oil has not just gone gooey, it's solidified into a crust. Paraffin wouldn't touch it. I chiselled off some on the base of the gearbox (the left side in the photo) but I didn't fancy this to work reliably long term, so here we go again, lets pull it apart!

This was after the selector cams had been removed. They were encrusted with solid oil. I scratched some off, tried a not too aggressive wire brush. In the end I tried acetone. Bingo! The only solvent that will touch this filth. I started gingerly as the cams are plastic (delrin, apparently) but this seemed resistant to the acetone, so off we go. A few hours of cleanup gets the cams, the shaft and bevel gears looking like this:

After a bit of panic over how I'd get the timings right again, I discovered that the cams are in fact 8 identical pieces. I took photos when I did up the longbed m300 so I know what the order is. They'll just need syncing with the knob. The jury's out on whether the other shafts will come out one by one for cleaning (probably) or get done in situ. Either way, it's a long job.

Lastly, some butcher had been at this long before I bought this lathe. The selector knob has been a bit mangled:

 

[RobCox]

Took a drive today to collect (and pay for!!) a replacement rear spindle bearing. New and old:

While I was there I mentioned I'd like a tidier selector knob for the QCGB and this was available so I bagged this as well:

Unfortunately for my finances this turned into an even more expensive day. The front brake calliper on my car seized on the way there. The chap I bought the bearing from, Ron, very kindly took off the very hot calliper and squeezed the piston back with a G clamp and lent me a brake hose clamp so I could drive home on 3 brakes. That'll be a garage bill for me then, I'm not in to fixing my own car. I did enough of that in my youth to my Austin A35 and Ford Escort.

Then, time for Sunday lunch:

15 minutes at 125 deg.C and the front bearing dropped on the cleaned spindle no problems. Then it was time to fit the bearing I'd just acquired into the headstock:

Once I'd got the spindle back in and the awkward circlip back in place I could get the new bearing inner fitted, grease up my home grown gaskets and get it roughly adjusted:

The gear selector controls were then fitted ensuring they were timed correctly:

And finally get the lid fitted. I'll sort the oil out another day. I need to make a new pulley for the motor so there's no drive yet and I need to go through the bearing adjustment procedure in the manual.

 

[Seadog]

Result!

 

[Brad93]

lovely job.
out of interest where did you sort the anti vibration mounts

 

[RobCox]

out of interest where did you sort the anti vibration mounts

They're Fibet mounts from RS Components:

CGM5023-M | FIBET Anti Vibration Mount, Universal | RS

uk.rs-online.com

Not cheap, but I bought these ones back in 2017 when I was doing up my longbed M300. I secured them on an m8 caphead and turned off the shoulder as the length of fixing bolt needed wouldn't fit into the motor feet from above. Had to turn them a few thou at a time as the shoulder on the top washer was only connected by the squidgy rubber!

 

[RobCox]

After a couple of days breathing in far more solvent than is good for me, the QCGB is looking a bit better. I got it stripped down this far:

To get the remaining shaft out you have to remove a metal plug in the side:

It's threaded M6 for a slide hammer or puller. I tried my makeshift slide hammer, then a threaded rod inside a tube with a washer and nut. No chance. It wasn't budging, so rather than waste any more time and to avoid the nightmare scenario of breaking the gearbox case (as it's only cast iron), I cleaned it in situ. Several cleaning cycles later (with care, the acetone eats the paint as well as the goo) it looks like this:

It's clean enough and will be fine. I stripped all of the chipped paint off the outside:

Then I set to work on the rest of the shafts and gears. Before...

and after:

Currently the case has it's first coat of paint, red oxide primer, drying in the workshop:

 

[RobCox]

More progress. The QCGB got several coats of paint:

Then I put the shafts back in:

The new oil sight glass got fitted at this stage too. The lower shaft has a bronze bush on the left hand side here. It's outside the oil seal and gets no lubrication, so I poked a little hole in the top side so oil will weep through it. Yes, it's going to cause an oil leak, but that's better than wearing out the bush. Apparently it's been redesigned on later models to move the oil seal outboard, but I'm not spending another fortune on spare parts. This lathe has already had it's fair share of expenditure:

The hole is 1.5mm.

Then I got the timing cams (is that the right name for them?) back in and selecting the correct gears on the 1-8 knob. I couldn't find anything on the web as to how these are arranged so I worked out how and why it should go, then videoed the reassembly which I'll pop on my youtube channel. Here it is selecting the gear in position #1:

 

[RobCox]

I also made a start on the electrical panel. With the WEG VFD the whole wiring is much simpler than the arrangement with the Teco VFD on the longbed that I did. This is the original panel:

and this is the panel arrangement before wiring up:

The VFD has to mount sideways as there's not enough depth to mount it so the display faces out. I'll make the wiring looms long enough so it can be mounted like this for setup and debug:

This is my wiring diagram for how I'm going to be connecting it up:

 

[Brad93]

I also made a start on the electrical panel. With the WEG VFD the whole wiring is much simpler than the arrangement with the Teco VFD on the longbed that I did. This is the original panel:

View attachment 485183

and this is the panel arrangement before wiring up:

View attachment 485184

The VFD has to mount sideways as there's not enough depth to mount it so the display faces out. I'll make the wiring looms long enough so it can be mounted like this for setup and debug:

View attachment 485185

This is my wiring diagram for how I'm going to be connecting it up:
View attachment 485187

What did you use to draw the wiring diagram?

 

[RobCox]

What did you use to draw the wiring diagram?

TinyCAD. It's a freebie download.

TinyCAD download

 

[RobCox]

More progress. The QCGB is back where it belongs:

The knobs are a bit messed up. While it would be nice to get them powdercoated and looking pristine that's further than I want to take this refurb. As long as they work ok, I'll live with them. If they really bug me in a year's time (they won't, the lathe will be scratched up then!), I'll do something about it.

A word of warning if you've got one of these lathes and you take the gearbox knobs off. Subtle differences change the engagement of the gears. When I first checked the operation when the box was reinstalled the leadscrew was always engaged, so the box came back off and I swapped the knobs around. Looking inside the box I checked the gear engagement with each knob and got an optimum arrangement so in every position the gears engage fully or disengage fully.

Then onto the feed gear train. The idler gear spindle either was made badly (that's the way it looked to me) or had been abused, but the thread was torn:

It was strong enough and rarely gets messed with, so I refitted it:

I finally bit the bullet and filled the gearbox with ISO220 and the headstock with ISO68:

The spindle preload still needs doing, but I'm waiting till the electrics are done so I can run the spindle under power.

As for the electrics, I tried to fit a new em. stop switch I'd bought. Unfortunately the fibreglass shell this fits in is about 8.5mm thick and the supplied nut won't go on and allow the switch mechanism to fit. The old switch is only a press to make and I need a press to break as there are 3 switches in series for this, em. stop, the cabinet cover switch and the footbrake. This is the switch with the original supplied nut fitted:

So, off to the longbed lathe in the garage to knock up a 3mm thick 22 x 1.5mm threaded nut. As it's all plastic the thread was some moulded pseudo square thread profile, so I used a small ACME insert to thread it. Even with the thin nut, there's very little clearance once the switch clicks into place:

I'm currently fighting the same battle with the pilot light. The old one had been damaged. The choice of new ones from RS Components gives no options that are a direct fit into the 12mm dia x 8.5mm depth hole. I seem to remember having the same issue with the longbed lathe and resorted to enlarging the hole, sacrificing the edge on whatever tool gets used to enlarge it (glassfibre isn't very forgiving).

Then I fitted a new 100mm pitch dia taperlock pulley onto the motor. There are 2 matched length belts. The old pulley had differing wear in the two sheaves. All nicely aligned and with the brake fitted afterwards (as it gets in the way of installing the belts:

The brake has been correctly assembled this time so the rod doesn't need bending and it won't rub on the pulley.

Also the coolant pump has been cleaned, stripped and the fresh paint job on the motor is currently drying. The tray of bits is visible under the lathe in the pic above. Fortunately the motor is dual voltage. It'll be driven using single phase and an 8uF Steinmetz capacitor.

Lastly, all the data plate mounting holes on the front of the headstock have been tapped M3 so I don't have to use those nasty little self tappers. One had already sheared off (bottom right on the threading chart) and as they're as hard as the hobs of hell there's no way of getting it out. Button head cap screws are much easier to replace:

 

[Brad93]

More progress. The QCGB is back where it belongs:

View attachment 485690

The knobs are a bit messed up. While it would be nice to get them powdercoated and looking pristine that's further than I want to take this refurb. As long as they work ok, I'll live with them. If they really bug me in a year's time (they won't, the lathe will be scratched up then!), I'll do something about it.

A word of warning if you've got one of these lathes and you take the gearbox knobs off. Subtle differences change the engagement of the gears. When I first checked the operation when the box was reinstalled the leadscrew was always engaged, so the box came back off and I swapped the knobs around. Looking inside the box I checked the gear engagement with each knob and got an optimum arrangement so in every position the gears engage fully or disengage fully.

Then onto the feed gear train. The idler gear spindle either was made badly (that's the way it looked to me) or had been abused, but the thread was torn:

View attachment 485692
It was strong enough and rarely gets messed with, so I refitted it:

View attachment 485693

I finally bit the bullet and filled the gearbox with ISO220 and the headstock with ISO68:

View attachment 485694

The spindle preload still needs doing, but I'm waiting till the electrics are done so I can run the spindle under power.

As for the electrics, I tried to fit a new em. stop switch I'd bought. Unfortunately the fibreglass shell this fits in is about 8.5mm thick and the supplied nut won't go on and allow the switch mechanism to fit. The old switch is only a press to make and I need a press to break as there are 3 switches in series for this, em. stop, the cabinet cover switch and the footbrake. This is the switch with the original supplied nut fitted:

View attachment 485695

So, off to the longbed lathe in the garage to knock up a 3mm thick 22 x 1.5mm threaded nut. As it's all plastic the thread was some moulded pseudo square thread profile, so I used a small ACME insert to thread it. Even with the thin nut, there's very little clearance once the switch clicks into place:

View attachment 485697

I'm currently fighting the same battle with the pilot light. The old one had been damaged. The choice of new ones from RS Components gives no options that are a direct fit into the 12mm dia x 8.5mm depth hole. I seem to remember having the same issue with the longbed lathe and resorted to enlarging the hole, sacrificing the edge on whatever tool gets used to enlarge it (glassfibre isn't very forgiving).

Then I fitted a new 100mm pitch dia taperlock pulley onto the motor. There are 2 matched length belts. The old pulley had differing wear in the two sheaves. All nicely aligned and with the brake fitted afterwards (as it gets in the way of installing the belts:

View attachment 485698

The brake has been correctly assembled this time so the rod doesn't need bending and it won't rub on the pulley.

View attachment 485699

Also the coolant pump has been cleaned, stripped and the fresh paint job on the motor is currently drying. The tray of bits is visible under the lathe in the pic above. Fortunately the motor is dual voltage. It'll be driven using single phase and an 8uF Steinmetz capacitor.

View attachment 485700

Lastly, all the data plate mounting holes on the front of the headstock have been tapped M3 so I don't have to use those nasty little self tappers. One had already sheared off (bottom right on the threading chart) and as they're as hard as the hobs of hell there's no way of getting it out. Button head cap screws are much easier to replace:

View attachment 485701

RS never has the right sized pilot lights, ebay usually turns something up.

You could use the original NO estop if you have a spare relay kicking about.

 

[RobCox]

You could use the original NO estop if you have a spare relay kicking about.

The absence of a suitable supply to power the relay coil makes that difficult. Unless of course I use a 220V coil, which I don't have.

I have had a look on ebay for an indicator. That might bear fruit, but ebay is not exactly overflowing with technical details, like a dimensioned drawing of the parts on offer, so it's a gamble as to whether it fits. I'll report back when I have a solution.

 

[RobCox]

Two steps forward, one step back. I adjusted up the spindle bearings according to the procedure in the manual. Axial play was about 0.00005" (half a division on a tenths reading DTI) when I'd finished, and the spindle rotated very easily by hand:

I've painted the coolant pump motor, fitted new bearings and seal since it was in bits. Bearings were ok but they're cheap and it's easier to do now. I assembled it on the coolant tank and got it wired up before fitting to the lathe:

Then the fun started. Oil leaking from the headstock on to the motor. First try, blame the drain plug. A hi-tech solution to avoid draining down the headstock - do a quick swap so I could wrap the plug in PTFE tape. I used a clean coffee tin to catch the oil as I swapped the plug:

I hunted for something to plug it while I cleaned the plug and wrapped tape around it. The quick bodge solution - an old isolation valve:

Got the plug reinstalled and tightened. At this point I pulled the back cover off the headstock to put the drained oil back, only to realise the fill plug is the same thread as the drain plug and would have saved half an hour of faffing about looking for something to plug the drain hole.

That was yesterday. Today there were more dribbles . A careful look see revealed the source of the problem - the input shaft oil seal on the headstock. Guess who chose not to replace it as it was all right:

The screw in the end of the shaft protects the threads in the event the pulley doesn't want to cooperate. In this case I could turn the puller screw by hand. To get here the brake's been disconnected, the motor adjustment loosened and the belts removed. All after I had got it adjusted just so!

In the meantime, the wiring on the electrical panel is moving on steadily. Now just waiting for parts to arrive:

 

[Seadog]

What's that they say about a ha'pen'th of tar?

 

[minimutly]

Crikey rob that’s one spicy meatball! I thought buying a matched pair of angular contact bearings for the omnimil was expensive!

Interesting (for me at least) to see that it’s a bearing at each end. In my head having a pair of bearings at the front was a Harrison thing and having one at each end was what colchester did.

I’m not up on the timeline but I guess by the time the ‘M’ lathes come along Harrison and Colchester were the same thing….

Did you order sealed or open bearings? My take is that for limited home use the sealed would be better?

 

[Brad93]

Always replace seals. Doesn't matter if you put them in twenty years ago or two weeks ago, they're throwaway items.