Harrison L5A refurbishment

Hi all

I am part way through a refurbishment of my L5A lathe which I rescued when the company I worked for was going to ditch it. It had had a hard life and I only started using it regularly in the last 3 years. This is not going to be a complete rebuild and repaint - I have too many other projects to tackle to do it justice. Maybe something for the future; just now my aim is to get it mechanically sound as much as I can so that it is a useful machine that cuts accurately, albeit it will look a bit tatty.

The bed is ok and I have refurbished the cross slide and top slide, replacing lead nuts and making sure everything is clean, well adjusted and well lubricated. I don't think there is anything wrong with the headstock or the main spindle bearings so I am leaving well alone there. Shortly after I started using it the motor burnt out so I fitted a new 3 phase with twice the rpm plus a VFD inverter so it now runs off 1 phase and has a top speed of 1500 rpm. I have now started dismantling the gearbox and saddle. Both were packed with grease, including in the nipples and oilways, as a result of which, most of the shafts and bearings in the gearbox and some in the saddle will need replacing/ remaking.

For most of the problems I have come across, I have found answers on this forum so my only question at the moment is about lubrication of the gearbox and saddle. I know that all lubrication is oil only on this machine and I can see how it works in the headstock with a closed environment and a sump of oil sloshing around and coating the gears. In the gearbox and saddle, the oil nipples will direct it to the shafts and bearings but how do you keep the gears well lubricated, particularly in the saddle which is completely open underneath? Same question relating to the change gear train.

Am I missing something obvious?

Chris

If you use a moderately viscous oil enough stays on the gears for most sessions. I don't know what oils Harrisons recommended, though it may be in the manual (mine is a photocopy bought from Tony Griffiths); but the saddle on an L5 / 5A is no different from most other lathes is being open underneath.

Some people use high-pressure bearing-grease on change-wheels, though not the saddle gearing. I just use oil, but I am not running either my L5 or Myford ML 7 so fast that they spin-dry the change- wheels.

I have found my L5's headstock is not especially oil-tight - but I think most emerges through the bearings. I keep a tray under the change-wheel guard to collect the oil that would otherwise end up on the floor.

Thinking about it, it is tempting to make a sloping "draining-board" to direct the oil dripping off the change-wheels into the chip-tray; but that would make the lathe much harder to clean and is probably not ideal if your lathe has a pumped coolant system.

To help keep the lathe itself clean, I cut some left-overs of ordinary plastic down-pipe lengthways to form gutters that are a gentle push-fit, held by their own elasticity, into the bed below the ways, under both headstock and tailstock. This is so swarf and oil-drips can be swept into the chip-tray instead of accumulating in the deep bed cavities.

As a by-product the gutter at the far tail end finds itself as a "hold-this-er" of small tools or work-pieces - as long as I remember they are there when pushing the tailstock back!

I will be using the modern day equivalent of the recommended grade, which is thicker that the headstock grade but it still doesn't answer the question of how to add lubrication to the gears on a regular basis. I am thinking of drilling a couple of holes in the top of the box to drip oil through, plugged with grub screws.

My headstock has not been leaking but when I removed the cover to look at the gears, there was a cork gasket fitted which was blocking off the channel to direct oil to the main bearing. I removed the gasket when refitting the cover and hey presto, oil leaked out all around the joint! I trimmed the gasket back so the oil channel was not covered and now it is leak free again.

I don't know if the headstock on the 5A differs much from that on the 5, but on mine the only way to verify and replenish the oil level is to take off the cast aluminium cover, held on with two 1/4 inch BSF cap-screws.

Mine didn't have a cork gasket but a sheet of thick greaseproof paper I took to be original, though I can't be certain. The poor thing was practically dry though, when I investigated!

Some of the Harrison lathes had a combined filler/sight-glass, but not mine. I have acquired one but not yet determined the best place to fit it. It will need me to drill and tap an appropriate hole, but the difficulty is knowing how high above the headstock floor the red line needs to be.

What may be worth doing, given that these headstocks obviously need enough oil in them for the largest gear to dip into, is going a bit further than just drilling holes to drip oil through, by making and fitting a proper oil filler-plug with combined dipstick.

Provided the headstock is not leaking anywhere, it should not be necessary to drip oil into it regularly, but one leak path to be aware of is the threads of the screws that hold the unit to the bed. I had had to dismantle mine to move it, and I think I fitted fibre washers under the screw heads on re-assembly. Oil going down there disappears into the cavernous void below, and either oozes out into the chip-tray or seeps down the screws holding the machine to its cabinet, thence onto the floor.

My headstock has the site glass and filler on the back of the machine. I will see if I can give you a measurement to work to to fit one to your machine.

When I talked about drilling holes I was referring to the gearbox housing.

If you give all the oil nipples on the saddle a shot of oil each time you use it, plenty of oil will work its way onto the gears.

Ditto the gearbox (mine also receives a certain amount of seepage from the headstock).

Sorry - I'm a bit confused by your use of "gearbox".

Apart from the change-wheels a Harrison L5 and 5A has 3 "gearboxes" but as far as I recall the only one under that that name is the small leadscrew / feedshaft range box below the headstock. The others of course are the headstock and the saddle.

The machine is provided with all the appropriate oiling points. You should not need to drill any holes in it!

My own L5 has no separate oil-filler on its headstock but it does have a drain-plug, round the back, so that might be some past owner's replacement for the proper fitting. I have bought a second-hand filler supposedly for a Harrison lathe but it is on a short threaded spigot bigger than the plug, so I wonder what it had actually been used on.

So I would be very grateful for the details , please.

All my references to gearbox are to the Norton gearbox on the front of the machine. My original concern was that the oil nipples on both the gearbox and saddle would direct oil to the bearings but not to the gears, however a number of correspondents have assured me that the oil does make its way to the gears.

My machine has a combined fill, drain and level unit fitted to a boss on the casting at the rear of the headstock. Hopefully the attached photo will help you determine whether your second hand filler can be fitted.

Ah, I see. Thank you. I didn't realise the 5 and the 5A were that different, though my example and I think the facsimile manual are quite early versions and mine does not have a Norton gearbox..

The filler you show is the same as the one I have bought, and its position does correspond to the drain-plug on my lathe, and again we could be comparing earlier and later versions as well as model designations.

Significantly though the fitting is clearly screwed into a hefty boss on the casting, and I don't think my machine has that. Whilst it would be fairly simple to make an adaptor, I don't know if the resulting reduction in pipe diameter will matter, but more important is it being at the correct height.

I can only try it, and if it doesn't work, re-fit the existing plugI

Juts noticed another difference. Yours seems to have a cast (aluminium?) belt-guard. Mine is a sheet-steel pressing, which I have modified along with cutting the original motor plinth off, so the machine is much closer to the workshop wall. I fitted the new, 3ph, motor on a frame above the headstock, built independently of the machine and putting it well away from the muck and dust, with the inverter and controller above the tailstock. I've also screwed a sheet-steel (part of a scrapped server!) splash-back to a shelf behind the lathe so its lower edge is within the chip-tray but not touching it, to prevent annoying, noisy vibrations.