My lathe is a small and quite elderly Zyto 3.3/8 screw cutting lathe in reasonably good condition. The headstock bearings are just plain metal bearings with no play or slop. Top speed at the moment is c600 rpm as measured with a laser tacho. I feel that this is a little slow for some small drilling and finishing cuts, and am thinking of introducing an extra range of speeds by adding a new pair of pulleys on the motor and intermediate shaft. What would be the fastest speed I could run at without risking damage to the bearings? I recently cleaned out the oil cups, replaced the felt packing and wicks and top them up each day.
Fastest recommended speed?
- Thread starter Norris
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skyline1
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Hi Norris
My Myford ML7 is a similar size and also has plain bearings, top speed as standard is 640 RPM AFAIK Myford do not recommend running them at faster than 1000 RPM so this may be a rough guide.
Hope this helps
Mark
My Myford ML7 is a similar size and also has plain bearings, top speed as standard is 640 RPM AFAIK Myford do not recommend running them at faster than 1000 RPM so this may be a rough guide.
Hope this helps
Mark
I think 1000/1200 rpm would be the fastest I'd take that lathe, and I'd go to a lower viscosity if the headstock warmed appreciably when running above 600/800 rpm.
The problem is that in failure the bearing is going to go rapidly from "I wonder if that's getting hot" to "oh crap!". I'd spend some time in front of it at speed watching for signs of it getting too hot before starting to pay attention to work. If it runs free for an hour without getting objectionably (can't hold your hand on it for 5 seconds) hot you should be OK for work.
But most of my plain bearing experience is at much lower rpm.
The problem is that in failure the bearing is going to go rapidly from "I wonder if that's getting hot" to "oh crap!". I'd spend some time in front of it at speed watching for signs of it getting too hot before starting to pay attention to work. If it runs free for an hour without getting objectionably (can't hold your hand on it for 5 seconds) hot you should be OK for work.
But most of my plain bearing experience is at much lower rpm.
goldstar31
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As Mark rightly points out the limits of the 'normal' ML7 are about 1000 but your lathe compares with the earlier Myford series, the ML1 to 4 and it is actually more flimsy than any of the Myfords.
This does not in any way denigrate the machine, I owned a similar machine which was sold by Tyzacks of London. Mine was inherited from a local doctor and he made endless Gauge 1 locomotives on it and a little Adept shaper. Digressing, he also wrote up much of his research in Model Engineer.
This, thank you Mark for jogging my failing memory, allows me to mention that spares and accessories will be like hen's teeth now. The source for such information is to go into British Public Libraries or a decent model club and get out the old Model Engineers from about 1953 and read up the articles of Martin Cleeve who wrote his improvements on the Myford ML7 but also the earlier Myfords which he owned. From these, he set to and modified similar small lathes such as the Super Exe which belonged to his friends.
I hope that this will expand the answer and be of constructive use.
This does not in any way denigrate the machine, I owned a similar machine which was sold by Tyzacks of London. Mine was inherited from a local doctor and he made endless Gauge 1 locomotives on it and a little Adept shaper. Digressing, he also wrote up much of his research in Model Engineer.
This, thank you Mark for jogging my failing memory, allows me to mention that spares and accessories will be like hen's teeth now. The source for such information is to go into British Public Libraries or a decent model club and get out the old Model Engineers from about 1953 and read up the articles of Martin Cleeve who wrote his improvements on the Myford ML7 but also the earlier Myfords which he owned. From these, he set to and modified similar small lathes such as the Super Exe which belonged to his friends.
I hope that this will expand the answer and be of constructive use.
MuellerNick
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The old Deckel mills had plain bearings (just for radial load, axially they have ball bearings) in the spindle. That went up to 2000 RPM. But you had to watch for the temperature! And if you worked at high RPM for most of the time, the bearing had to be opened a tad.
Lubrication was just hydraulic oil (grade 46) with felt oilers. Nothing fancy, no pump, no circulation.
Nick
Lubrication was just hydraulic oil (grade 46) with felt oilers. Nothing fancy, no pump, no circulation.
Nick
goldstar31
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As memory returns(?), there is a lot on the Zyto on 'lathes.co.uk'
Worth a look- and then a second one
If you are short of 'cogs' I would suggest that 20DP 'Myford' type gears should fit OK.You will probably the problem of a slow finishing gearing as the standard banjo will not readily take banked gears. You can get around this by fitting the slow speed one that was sold to fit the ML7. Cleeve, if you are so inclined, made a self act gear box top designed to fit the ML7.
I used to have interesting 'goodies' and it all rather boring to have everything hidden in a gear box.
Again, you will probably not have the luxury of dials on your lathe and Cleeve and a David Lammas both wrote up how they made them to fit small lathes.
I can promise that you will learn a great deal from your machine but treat the old girl gently.
Worth a look- and then a second one
If you are short of 'cogs' I would suggest that 20DP 'Myford' type gears should fit OK.You will probably the problem of a slow finishing gearing as the standard banjo will not readily take banked gears. You can get around this by fitting the slow speed one that was sold to fit the ML7. Cleeve, if you are so inclined, made a self act gear box top designed to fit the ML7.
I used to have interesting 'goodies' and it all rather boring to have everything hidden in a gear box.
Again, you will probably not have the luxury of dials on your lathe and Cleeve and a David Lammas both wrote up how they made them to fit small lathes.
I can promise that you will learn a great deal from your machine but treat the old girl gently.
