Denham Junior Mk2 Lathe Purchase

Hi. A new lathe owner and first post on the forum.

After a few years on the lookout for a lathe, I took a punt on a old Denham that was fairly local to me. The price seemed reasonable so bought it sight-unseen. From what little research I’ve done, it’s a Denham Junior Mk1 made in 1929 and according to the info plate, reconditioned in April 1949. It’s somewhat rough but overall it seems to work so the plan right now is to restore it into a good a working condition. Basically just go through it, clean and repair anything that needs it and give it a coat of paint.

Is there any fellow Denham owners on this list who can share their knowledge on this model? I’m also looking for any documentation: Service manuals, operating manuals, parts list etc that will help with the process.

I expect that "AM" is Air Ministry.. I have a Denham DL6 or 7 (I can't remember which. It is quite slow and TC insert tools are not supposed to work with it. They do! Productivity is significantly improved with 2 axis DRO.

John

Likely it was thoroughly worn out during the war years when it would have given sterling service for the war effort.

It may be due for another reconditioning, but likely still in fine fettle, the only drawback is the speed range - but keeping the speed down would have made it so long-lived.

Modern lubricants may allow that range to be extended, but better left as it is. Some TC cutters will work very satisfactorily - the polished ones designed for cutting aluminium at high speed are good with other metals if care is taken with their use.

That it has a separate power feed shaft (not using the lead screw for that duty) sort of demonstrates the quality of the machine.

I would say that looks like a good starter machine, although some on the forum would always recommend a new (chinese) machine. It has clearly stood the test of time. Enjoy.

It looks like it could clean up really well

A DRO as mentioned makes life much easier with those old ladies

Edited By Ady1 on 11/11/2021 10:07:10

Hi John,

The guy I bought it from did say it was likely from an air base up in Lincolnshire. I'm assuming it's the low speed that's the issue with using inserts? It didn't come with any tooling so I was going to purchase some 12mm holders (the height from the post to centre looks to be 1/2". HHS would be nice but I don't have the skills yet to make them (or even a suitable grinder).

A DRO is a possibility down the road but not right now.

I've just noticed the type-o in the thread title. It should me a mk1: can a moderator change this?

The gear head is what drew me to it over some of the belt drive models, more like a mini Colchester student (the only lathe I've ever operated). It all looks original going by period photos I've found. It could look quite smart with new paint. It's missing an on/off control, you just plug it in to start it which seems a bit sketchy from a safety standpoint.

Do you know anyone on the forum that has a mk1? There's so much I don't know, like how much oil it takes, what taper fitting the tail stock is, etc.. I'm also worried about breaking something that cannot be replaced when stripping it down. Having some documentation would really help. There's a little history on lathes.co.uk but not much else.

check your inbox

I suspect there will be an oil level plug in the side of the casing. Some old machines had a sight glass/tube or two taps - one for max level (allow oil to drain until at max level) and the oil level was OK if there was oil at the lower valve (when cracked open).

I suspect the level might be just above the teeth on the smallest gear on that intermediate shaft - to allow pick-up with all three gears on that shaft. It will also be below any potential leakage points - gear change levers and shaft bearings.

I expect the large gear will pick up, and splash, plenty of oil for the bearings or the oil will be picked up by the gear in the lower section of the box, at the left side in your pic. Unless there is a separate oil-slinger or pump (unlikely). Are there any oil channels in the top cover?

Looks to be a very nice machine, don’t worry about low speeds I have an old Holbrook that is a bit challenged in the speed department and have never had a problem using tipped tools at slow speeds. Have you got any other chucks etc for the lathe, can’t quite make out from the photo what’s in the box underneath it.

A kind member has emailed across a manual for the mk2 which from the look of it shares a few similarities with my mk1. There seems to be no fill-to mark on this version. I think it might just be trial an error. Shell-Mex R-1 no longer made so ISO 32 to 68 I guess, I use 32 for my compressor but seems a bit thin so might try the latter.

Lubrication is splash by the gears only, no pump. The cover has some channels but some oil holes seem to sit under sides that don't, very odd. Externally there are many oiling points, flat with a sprung ball bearing inside. Is there a special oil can that fits these? Not come across this type before.

I also have an early Keighley lifts Mk1 lathe with the plain bearings.

Has been happy for some years now being fed ISO 68 oil. If a dial indicator is used to indicate a workpiece while turning the chuck by hand, you can see the small difference when the oil film is established & see the change as the spindle settles when rotation is stopped.

Although i did take approx 11mm off the topslide casting to allow larger tooling & fitted an adjustable height toolholder. Very happy with the lathe, but still need to add graduated handwheels at some point !

Well done you, she looks much better now

Smart to gather info before acting! If not done already see lathes.co.uk's description, who say 'literature available'.

My advice is not to jump in at the deep end by dismantling. Not even if you're a experienced mechanic certain you know what you're doing! Instead put the lathe carefully through it's paces, familiarising yourself with the controls and finding out how the machine cuts metal.

Older machines are likely to be worn, with incidental damage, and missing accessories. We've no idea what it's been doing in the last 73 years, thrashed or cosseted!

I think the hobby lacks an in-depth guide to evaluating old machines, but this is how I'd approach it:

1. Remove superficial muck and re-oil. Note obvious wear
2. Confirm electrical safely. Wiring in good nick: rubber perishes, vibration breaks insulation at holes etc. Switches work correctly. Metalwork all earthed, no tingles. Old tools rarely meet modern safety standards so maybe fit a combined No Volt Release/Emergency Stop
3. Turn by hand to make sure nothing's jambed and controls work. Check what change gears are fitted
4. Confirm motor runs, no magic smoke or overheating
5. Let it run off load for 30 mins, feeling the bearing areas for untoward heating. Warmish is OK
6. Buy a Free Cutting metal such as EN1A-Pb for testing. Avoid scrap because it can mislead by cutting badly
7. Get a sharp HSS tool to test with. Old machines often come with odd HSS tools, all blunt.
8. Run through a series of cuts noting trouble. Start by moving the cutter with the compound slide and saddle manually, then try the auto functions. Move from slow light cuts showing the lathe moves appropriately to deep fast ones proving it's OK under load. Test all the gearbox speed settings, reverse and back-gear etc. Check half-nut engages the lead-screw along it's full length and in the high wear area near the chuck. Move from plain turning up to facing, threading and drilling from the tailstock. Parting off is a tough test. Finally, DTI check alignment by cutting a test bar

Hard for beginners to tell the difference between problems caused by:

1. doing it wrong: RPM, Feed-Rate, Depth of Cut, cutter shape & setting, overhangs, iffy work-holding, maladjustments, bad technique etc.
2. difficult materials that challenge a pro machinist with a lathe in GWO
3. machine faults: slipping belts/clutch, worn bearings, hollowed slides, worn leadscrews/half-nut, cracked body, duff repairs, bell-mouthed chuck, bust shear-pins, stripped gears, rust etc.
4. Maladjustments. Gibs, twisted bed (see Rollies Dad if the lathe cuts tapers), blunt tools, loose tool-post or saddle
5. Don''t trust previous owners! Gibs fitted upside down with their screws not in the dimples, oil-ways blocked by grease, misfit parts from other kit, missing nuts, bolts, washers, grommets, cable clamps and sub-assemblies, dodgy electrics, paint & putty, stupid mods, belts wrong size, profile and overtight, misaligned motor/pulleys, and bodge repairs. Every time a tool is moved, there's a chance it's dropped causing bent shafts and controls etc. Maybe spindle bent by lifting with a rope around the chuck.

So I advise running the machine before anything intrusive. Save deep cleaning and major dismantling for later.

Nothing highlights faults like cutting metal because it stresses the whole machine emitting showers of audible and visual clues if anything is wrong. Inexperienced owners who start by stripping down and reassembling can cause more problems than they fix. Extra hard to diagnose mixes of predictable problems due to wear and weirdness caused by new mistakes.

The external appearance of machine tools isn't a good guide to condition. Paint and polish make wrecks look good, whereas a scruffy old lathe might be fine mechanically, ready to go after a few checks.

Step 1, I suggest, is to start by finding out what needs work by testing by doing. Take notes, don't jump to conclusions, ideally not fixing anything yet unless it's straightforwardly obvious. Don't take a working gearbox apart until certain the problem isn't an easily replaced shear pin. Collect evidence and think before acting. Not rocket science but lathers have subtleties. Easier to diagnose and fix lathes after a bit of experience.

If faults are detected, ask the forum. Many are easily fixed and others don't matter because the operator can compensate for them. Most worrying are the issues likely to be more time, trouble & money than the owner cares to take on: regrinds, costly bearings, and impossible to find essential spare parts. A large number of small faults might add up to more trouble than the machine is worth.

Special case: many people enjoy restoring old machines as a hobby. For them, lots of difficult faults are just more fun! But not if you want to get on with making things.

Amazing though how much good work is done on wonky lathes by skilled operators, so don't rush to reject it either.

Dave

Don't forget, it is a plain bearing lathe (like my Covmac), so it is essential to oil all the oilholes and cups before you use it, and don't forget the tailstock ends of the leadscrew and feed shaft! It looks like a lovely machine!

Phil

I'm afraid this is a different lathe than the one pictured by the original poster ! Mine was in quite good condition when i got it, so didn't need much work to get it working well. Other than having to use a 240v to 240v transformer to prevent tripping due to large inrush current on starting the motor.

Maybe light blue was the original colour for the MK1 though.