Harrison L5 Metalworking Lathe (1950) Teardown & Overhaul

[Fergie 307]

On mine, a 5a with the high speed shaft, I reconfigured the original coolant switch to give two positions. These control two pre set frequencies on the vfd. The original 1.5hp 1400 rpm motor has been changed for a 3hp 2800rpm. So I tweaked the lower frequency to give the same top speed as the original plate on top of the machine. The higher setting runs the motor at full speed, giving a top spindle speed of 1500 rpm. I then used a laser tacho to get the hi range speeds in each gear. I got a local print shop to make up a new speed plate, using an old two range plate as a pattern, so I now have the plate showing the correct speeds in each gear and speed range, imitating the set up on the machines that originality a two speed motor. Obviously the new plate is printed rather than the cast original but looks ok.
And Harrison's are well known for being quite noisy. The headstock gears are all hardened so they ring, especially when it's at full speed in the high range. Mine isn't too bad but some do make quite a howling noise!
Excuse the horrible modern stop switch. I have the original plate with green an red buttons, but the associated switches were well past their best. It's on my to do list, in the meantime this was one I had lying around.

 

[Fergie 307]

I should add they printed a number of the plates, so I still have a few if anyone is interested just pm me your details and I can post you one.

 

[Fastdruid]

I got a local print shop to make up a new speed plate, using an old two range plate as a pattern, so I now have the plate showing the correct speeds in each gear and speed range, imitating the set up on the machines that originality a two speed motor. Obviously the new plate is printed rather than the cast original but looks ok.

I like that. Unfortunately not much use with the infinitely variable control that a VR gives. I left the original alone and stuck this above the lathe. It gives an idea of rough speeds at a given frequency and then can use the tacho to fine tune things (note that although the motor is rated 5-90Hz I'm sticking to +/- 33% from 50Hz).

I've attached a version of this I recreated (I lost the file from the one I initially created) if it is of interest in working out the relative speeds.

And Harrison's are well known for being quite noisy. The headstock gears are all hardened so they ring, especially when it's at full speed in the high range. Mine isn't too bad but some do make quite a howling noise!

I don't actually think mine is very noisy at all. I mean it's not quiet but from reading about them I thought it would be horrific. Most of the noise is from the motor itself.

Excuse the horrible modern stop switch. I have the original plate with green an red buttons, but the associated switches were well past their best. It's on my to do list, in the meantime this was one I had lying around.

Better than mine there. Mine is horribly modern as the original had a massive great contactor on the front (unlike the newer ones which have a nice control panel). So I cut a hole in the cabinet akin to the newer ones and fitted a panel with the controls etc on...but modern ones.

 

[Sideways]

PM incoming Fergie,
I like your new speed plate and would be pleased to adopt that.
For me, I'll stick to 1500 as my top speed until and unless I have the need to go faster.
Thanks for the offer to share

 

[Fergie 307]

I have got that, will get it off to you over the weekend. I have limited mine to 1500 purely out of respect for the old girl. She is slightly older than me, and I know I certainly cant run as fast as I used to !
Many people of course choose to vary speed with the vfd, I suppose I am a bit old fashioned and still prefer to use the gears. You can of course combine the two to fine tune, whatever suits best for your particular needs.

 

[Fergie 307]

I like that. Unfortunately not much use with the infinitely variable control that a VR gives. I left the original alone and stuck this above the lathe. It gives an idea of rough speeds at a given frequency and then can use the tacho to fine tune things (note that although the motor is rated 5-90Hz I'm sticking to +/- 33% from 50Hz).

I've attached a version of this I recreated (I lost the file from the one I initially created) if it is of interest in working out the relative speeds.



I don't actually think mine is very noisy at all. I mean it's not quiet but from reading about them I thought it would be horrific. Most of the noise is from the motor itself.



Better than mine there. Mine is horribly modern as the original had a massive great contactor on the front (unlike the newer ones which have a nice control panel). So I cut a hole in the cabinet akin to the newer ones and fitted a panel with the controls etc on...but modern ones.

I was a little concerned at halving the frequency for the lower range, as I know some motors aren't keen and can overheat. This one is fairly modern and runs quite happily at half speed. I am old fashioned enough to prefer using the gears for changing speeds, but can certainly see the attraction of your set up. I am with you on some of the modern ones that look more like a jukebox than a machine tool.

 

[Fastdruid]

I was a little concerned at halving the frequency for the lower range, as I know some motors aren't keen and can overheat. This one is fairly modern and runs quite happily at half speed. I am old fashioned enough to prefer using the gears for changing speeds, but can certainly see the attraction of your set up. I am with you on some of the modern ones that look more like a jukebox than a machine tool.

Mine is inverter rated down to 5Hz but still, I prefer to keep it 33-66Hz. If I was to run it any less I'd want an additional fan on it.

 

[sploo]

Always worth checking the motor specs if you can find them. The one that came with my Colchester Chipmaster turned out to be rated for some crazy range. I can't remember the exact numbers but from 50Hz nominal it can handle 100Hz down to something daft like 5Hz. Power drops off significantly at lower rpm, but the motor can do it.

 

[Fergie 307]

PM incoming Fergie,
I like your new speed plate and would be pleased to adopt that.
For me, I'll stick to 1500 as my top speed until and unless I have the need to go faster.
Thanks for the offer to share

In the post to you this morning. Good idea to put a smear of Hylomar or similar on the threads of the screws that hold the plate on. Otherwise over time oil seeps past them and puddles in the top under the plate. My perspex cover was pretty much opaque, I made a new one out of some clear acrylic left over from windows in a wendy house I made for my daughter, been sat behind my bench for best part of twenty years in the basis that it might come in handy one day!

 

[Sideways]

Excellent advice I'll take it.
Elsewhere, I've not started on gaskets yet. Mine leaks in fine style from around the headstock top cover, also slowly through the bolts down into the bed. Not too much, but enough to supply my oily rag maintenance regime. I believe that BMW engines for example are actually deigned to consume oil, so I don't see this as a problem for now as long as I keep an eye on the levels.

 

[Fergie 307]

Excellent advice I'll take it.
Elsewhere, I've not started on gaskets yet. Mine leaks in fine style from around the headstock top cover, also slowly through the bolts down into the bed. Not too much, but enough to supply my oily rag maintenance regime. I believe that BMW engines for example are actually deigned to consume oil, so I don't see this as a problem for now as long as I keep an eye on the levels.

The top cover I find is best done by putting a thin bead of automotive type silicon round the cover, about a millimetre or so wide. Hate the stuff normally, but for this it is very good. Let it go off a little till it's tacky, then put it on and just nip the bolts up not much more than finger tight. You need to be careful to keep it close to the outer edge at the front so you dont risk any getting into the oil trough round the front of the casing. If you rub a little Vaseline over the mating faces on the headstock before you put it on it will still seal but the silicone will stick to the cover, not the casing. You can then take it off maybe a couple of times and replace it before you have to redo the sealant.
For the bolts, a little Hylomar or Wellseal under the washers should do the trick. Just do them one at a time to avoid it moving. To clean all the oil out of the head I find one of the oil full guns for filling gearboxes is very handy. Basically a big syringe with a body like a grease gun, and a plastic hose. Enables you to easily suck up the last of the oil from the bottom of the case, and any sludge that collects there.
Can't remember now if you had the gap in yours. If not then you might want to make a plug for the hole in the bed under it. On mine so much crud and oil had accumulated in the hollow section under there that it had started to bleed out around the joint with the chip tray. Used a piece of plastic pipe on my shed vac to clean it all out. Probably got a couple of mug fulls out of there eventually. Now if I take the gap out I have a rubber plug to pop in.
A tip my dad gave me for these is that the strip at the back of the saddle is a potential spot for wear, and has no specific lube points, it relies on oil you pump into the way oilers working it's way down. His tip was that as well as giving all the oiling points a couple of strokes from time to time during a session, when you have finished for the day give the rear way oilers in particular a good feed, that oil then has plenty of time to work down into the rear strip before you use the machine next time.
Oh and for lubricating the change gears I find the spray motorcycle chain lube is good. Tends to stay put on the gears rather than all over the inside of the covers.
Have fun.

 

[Fergie 307]

Lastly while I remember. If your white knobs on the machine are in a poor state, which they often are, I found it quite difficult to get hold of white ones of a decent quality from the normal places. The knobs on mine I stumbled across on e bay. They are actually sold for joysticks on gaming consoles. They do all sorts of sizes and colours including white. They come with an M6 brass insert. They knobs are a thermo plastic of some kind, so I found the easiest way to remove the insert was to use a piece of M6 threaded rod. Just heat it up a bit then screw it into the insert. Once the heat spreads to the insert it softens the plastic around it and you can just pull them out. They are then easy to drill and tap to the correct size Not sure exactly what they are made of but good quality finish with no central ridge. I was a bit concerned they might discolour, but they seem impervious to oil and coolant and still look like new after more than two years of regular use.

 

[Sideways]

Making some progress on the clutch upgrade. I've identified a modern material that may make a good replacement disc and an excellent supplier who is educating me about the materials and processes. A number of folk from the Harrison lathe group have all contributed measurements and from that I'm having some friction material made and precisely ground to thickness as this seems to be important to the correct operation of the clutch. More to come on that story.

Meanwhile, I'll have to strip my own clutch for machining to reinstate the driving pins that are needed for the 3 plate design.
First job - get a pin hook spanner as the compression nut on the clutch shaft is distinctly harder to undo than it is to tighten up
Here's the end of the lathe with the cover off:

And while I'm at it, the clutch lever which I had not previously taken apart.
There's a boss which turns L and R, the lever on a sizeable straight pin. Small grubscrew from above locks the pin in place. A spring loaded plunger holds the ball end of the lever down. Lifting the lever raises a square tooth from a notch and allows the clutch lever to move R which in turn causes the clutch to grip.

 

[Fastdruid]

FWIW I've found just using a suitably sized pair of drill bits in the holes for the clutch nut gave sufficient leverage to undo it. Certainly a pin hook spanner would be useful but I've never found I actually needed one.

 

[Sideways]

FWIW I've found just using a suitably sized pair of drill bits in the holes for the clutch nut gave sufficient leverage to undo it. Certainly a pin hook spanner would be useful but I've never found I actually needed one.

My nut has just one pin hole in the outer edge, not the face. It accepts a 4.5mm drill bit, maybe a 4.8mm but 5.0 is too big.
This worked great for tightening it by hand against the spring but strangely it is harder to loosen than to tighten. I snapped the 4.5mm drill and nearly skewered myself. I'll be more careful next time !

 

[Fastdruid]

My nut has just one pin hole in the outer edge, not the face. It accepts a 4.5mm drill bit, maybe a 4.8mm but 5.0 is too big.
This worked great for tightening it by hand against the spring but strangely it is harder to loosen than to tighten. I snapped the 4.5mm drill and nearly skewered myself. I'll be more careful next time !

Mine has two but same design, holes on the outside edge. I wonder if it's because yours has been tightened up more than it should be because of the missing plate. Yours looks almost coil bound while mine is barely tightened. FWIW there isn't a procedure in the manual beyond tightening it until it doesn't slip. I tightened mine by hand until it didn't slip turning by hand while holding the chuck with a bar then 1/2 turn more. Check it released properly and job done. I figured in general it's actually better to slip at the extremes as it could save things getting nasty if you have a crash or something digs in etc.

 

[Sideways]

Mine certainly slips on excessively heavy cuts - that or it's the belts slipping. I agree it's a good thing to prevent damage.
You can see how the inner steel plate of my clutch sits lower the face of the pulley vs yours standing proud. The 5mm of the missing 3rd plate will account for that.
Having no friction <=> friction surfaces in contact, I'd expect mine to slip more easily than it should.

Anyway I've been able to borrow a hook + pin spanner from a friend with a later model 11" L5A so I hope it will come off tomorrow

 

[Fergie 307]

Once you have it all sorted and clean you should find you can adjust it without tools. A work glove with a rubber palm gives enough grip. With the plates in good condition it shouldn't need to be very tight. The old ones are easier as you only have the clutch. Getting the brake/ clutch balance right on the later ones often involves a lot of fiddling about.

 

[Fergie 307]

Judging from the pictures it looks to have cleaned up really well, I can imagine a fair bit of work went into getting it looking like that. Out of interest is your speed selection lever a similar design to the clutch lever, where you have to pull it out before moving it, or the type with no detent.

 

[Sideways]

The high low range lever on the front is like my clutch lever. Theres a detent so you pull and swing it from one side to the other. That's one of the features that lathes.co.uk mention as a difference between a mk2 and mk3 version of the L5.
I'm learning that these mk2, mk3 designations are kind of artificial tags that weren't used by Harrison and there's more gradual improvement than I realised.