Lathe service

My lathe, a Chinese made AL 250 is almost exactly three years old. I brought it new and have had little trouble with it. I do not want to stir up the hoary old debate about Chinese made machine tools, suffice to say that I got what I paid for, a fairly robust machine at an extremely affordable price. I had the usual problems that most people experience but a little judicious work with file, scraper and emery paper generally set things right. Lately I had noticed excessive backlash in the apron handwheel and thought that it might be time to give this a bit of a service. I estimate that the lathe has about 2000 hours of operation. Generally I like to keep the machine clean, at the end of the day I vacuum it down to get most of the chips and then a final blast of air in the more inaccessible spots. There is a cover of sorts over the leadscrew and I fondly imagined that this, along with my cleaning would keep most of the crap out of the apron gearbox. As the photos show, this was not quite so. To the casual observer it might look like one hundred years of neglect. On the good side, there was very little wear that I could detect, all the shafts just run in the cast iron holes, not a bush in sight. Most of the machining looked OK, finish and final assembly is what pulls everything down a bit. A good clean, new oil in the gearbox, fix the backlash problem (three loose screws) and back on the lathe, good as new. I cannot see how I can prevent this from re-occurring, I know there are those who will say it is caused by using air to clean down and I can see how some of it can be blamed on this, I accept that. However, given that it is quite easy to remove and service the apron, (it took me less than an hour from start to finish), I intend to do this on a regular basis, say every 200 hours. Cheers, Peter.

Thanks for posting this. I'm refurbishing my Taiwan 14x40 power feed assembly so closely examining my power feed driveline - the rotating feed bar, worm gear & brass helical-type gear. It's been a long, convoluted story but hopefully on the home stretch now. Coincidentally I'm just now pondering lubrication for the worm/helical brass gear for reinstallation. Somewhat like yours, it resides exposed & awkwardly inaccessible on the back face of apron. My internal apron gears are greased (as opposed to sealed apron oil bath) & are in great shape. So I was initially thinking of greasing the worm gears too. But I have been warned that grease is great at attracting & debris/cuttings & can do some real damage once inside the teeth.

I'm shocked you haven't seen badly eroded teeth or worse, particularly the brass helical type gear that engages the hardened steel worm gear. How was that lubricated on your lathe? How do you figure so much mung was collecting in there? Is that what you mean by the air not reaching? Not intending to make you feel bad, but this is exactly what I'm trying to avoid. My other idea was an sheet metal enclosure so gears could be well greased but completely chambered & isolated. I could rig up an oil feed tube that pointed to the gears & maybe a daily oil shot would lubricate & help wash anything down. But lubrication is one thing, sticking debris is another.

BTW, hopefully your lathe parts supply is better than mine ('98 vintage) because those gears are getting to be unobtanium & a bugger to make. They weren't too expensive so I figure having a spare of this 'wear item' is good investment. No gear = no power feed.

My lathe, a King 14x40

You nailed it on the compressed air. Never use it when it could blow stuff into places. Only where it will blow stuff away from places.

I only use it for a quick 'clean' of chuck scroll and then gently.

It's better to brush and wipe, disassembling as necessary, than blowing junk into the 'cracks'.

Pete

D,

As you said, "To the casual observer it might look like one hundred years of neglect"

Paint and oil slicks don't do the cutting, the lathe tool does. Unless of course you are a machine polisher, which to me,does more harm than good, as the excess oil can clean out areas you can't see.

I purchased my machine, A Chester Crusader a few years ago (can't remember anything from that era) but most probably somewhere between 5 and 7 years ago. Once I had done the usual commissioning on it, a couple of days work, it has since been over lubricated to a state where there are oil drips and stains all over the thing, Nothing has moved or gone wrong except for a duff motor which Chester changed overnight.

All you need to worry about is if the machine gives what you want from it, and if it does, then keep on sticking oil into it, it won't do it any harm.

John

Cleaning machine tools with compressed air will do that. That's why it's banned in industry, aside from the safety aspect to eyes etc.

Something else that might help keep swarf at bay is attach a four or five inch wide flap of vinyl (offcut from upholsterer) to the leading edge of the saddle. It lays flat over the lathe bed ways right were most of the swarf falls. Make it wide enough to stick out over the lead screw and the rear of the bed. It acts like a chip tray but does not get in the way of the chuck of faceplate so much. Flick the swarf off it and over past the back of the bed with brush every now and then. This way, most of the swarf never gets on the machine to start with, - straight from vinyl "bib" to drip tray. Been doing this on my ancient flat bed lathe for years with great results.

Hopper, that is a great suggestion! Cheers, Peter

Peter, I have a 9 x 20 Chinese lathe and did this mod as described by Steve Bedair in his web site. Very pleased with the result. It is also very handy for catching small machined objects. Norm

Thanks Norm, I can see the sense in this, I think it was what Hopper was referring to. I have copied the pic so that others can see the mod. Thanks to Steve Bedair. Cheers, Peter.

deeferdog said:

Thanks Norm, I can see the sense in this, I think it was what Hopper was referring to. I have copied the pic so that others can see the mod. Thanks to Steve Bedair. Cheers, Peter.

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Yes, that's the ticket, exactly. I would not be without one.

Fitted the ways cover as per Hoppers suggestion. I used some 4mm neoprene insertion rubber. When I really looked at the problem I could see that the major portion of the crap that ended up on the leadscrew came from the leadscrew cover. The swarf would land on the top of this and it would slowly slide off due to vibrations etc. and mainly into the swarf tray. However the part of the cover that happened to be behind the carriage apron, the metal bits there could only fall onto the power feed gears and the half nut. From the same neoprene I cut a wiper and glued that to the carriage. Now when the carriage traverses the lathe, the wiper sweeps all the crap off the leadscrew cover. Hope it works. Thanks to all those who took the time to comment. Cheers, Peter

First time I've seen a wiper on a leadscrew cover. Looks like just the ticket.

I have the exact same lathe. The biggest issue with mine was actually paint at the underside at the way. Even when it was adjusted tight there was paint in between that prevented the sadle to be solid. Otherwise just by taking the whole saddle and apron apart, clean out swarf and debur parts, then adjust everything, the lathe became a whole different beast. I did get a new self centering HBM chuck though.
I got a 38cm (15&#8221 long alignment test bar with MT4 shank that fits directly in the spindle. The alignment is actually very good even at the end at the bar. So no complaints about the potential accuracy of this lathe.
These lathes seems to need some attention before they are fully serviceable, but it looks like you can do the most with just TLC.

Like those ruber details..

I made a tempory one of these from a coke can cut up and laid across the saddle as shown above. I say tempory as it needs something more ridgid and substantial. But it's a great idea and does help with clean up.

Another tip if your using the 3 or 4 jaw and not passing a long piece of barstock through the spindle bore is to loosely pack some toilet roll at the rear of the jaws, insert your bar stock and the tissue will compact a little,but prevents all the small chip pieces getting into the rear of the chuck. When done machining, pull it out and discard, chips clinging onto the tissue. Saves blowing air or trying to get a cloth/Hoover in there to clean it out.

Peter I use air and common sense to clean the lathe and mill. By paying a bit of attention to the sequence and direction of air blasting I have no problem gunking up the apron. Regarding the back lash. Although I do not recognize your lathe model, it look exactly as my Sieg 9"X20". The cross feed nut has a radial cut almost to part the piece in two. A setscrew on the top slide is intended to jams in between the two parts, spread them slightly and eliminate the backlash. That was the intent of the design. The builder fumbled up an nothing line up to work as intended. When I made an oversized leadscrew I made the matching nut the correct length and now it works as intended.

I do not want to stir up the hoary old debate about Chinese made machine tools,

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I do not want either but believe I got good value for the money and a machine that can make her own spare parts or modification of any part I do not like. A funny thing is happening, as the machine and the operator age, the machine is making better parts and less screw ups. Like wine my lathe get better with age.

I have spring covers on my leadscrew so don't have the swarf problem. I have to say deeferdog's solution is simple and elegant, it allows for easy oiling and keeps the crud off.

Myford lathes have MT2 sockets in headstock and tailstock. Spirit (whiskey, brandy, etc.) bottle corks are just the right size to plug an open socket.

Dave
The Emerald Isle

deverett said:

Myford lathes have MT2 sockets in headstock and tailstock. Spirit (whiskey, brandy, etc.) bottle corks are just the right size to plug an open socket.

Dave
The Emerald Isle

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That may be true of newer ML10, or ML7 lathes, but mines an early ML4 and is MT1 sockets at both ends. I do however like the idea, and I think a rubber bung could be found to stop swarf finding it's way into the bores 😀

deverett said:

Myford lathes have MT2 sockets in headstock and tailstock. Spirit (whiskey, brandy, etc.) bottle corks are just the right size to plug an open socket.

Dave
The Emerald Isle

Click to expand...

That may be true of newer ML10, or ML7 lathes, but mines an early ML4 and is MT1 sockets at both ends. I do however like the idea, and I think a rubber bung could be found to stop swarf finding it's way into the bores 😀

Jon

Nah, lad! Put one of your evening suits on, get 12 or 15 courses washed down with a different wine at each and then try to stand up for all the toasts with the port going correctly around the table- and then try to collect the corks afterwards.

I tend to forget to ask for them but old age and alcohol are terrible combinations

Hic!

N