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Thread: Lathe lubrication
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19th Oct 2012, 03:54 PM #46Most Valued Member
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Hi Simon,
That was the only reason, apart from oil not reaching them that I could imagine.
Sounds like you could remove the seals on the bearings that get splash or bath oil.
Probably not much to gain by doing it - though it would drop the bearing temperatures at very high speed.
My Waldown toolpost grinder is interesting in that the spindle bearings use an oil bath to keep their cool, and for lubrication.
BUT when you service the spindle you pack the open bearings in grease during reassembly and add oil to the bath in the spindle later.
The oil washes the grease out very quickly (at 20 - 30,000 rpm it's no surprise).
The spindle bearings subsequently run at a much lower temperature in the oil only situation. Huge difference at those sort of bearing speeds.
I contacted Brobo Waldown over this and that's how it's laid out in the manual they sent me - interesting.
So if the oil washes out the grease on your much slower speed bearings it's no big deal - probably an improvement
Same situation when reassembling gearboxes (eg Holden), you use grease to keep all the needle rollers in position, and it just washes out later.
Cheers
Rob
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19th Oct 2012, 04:08 PM #47Most Valued Member
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Thanks Rob, thats interesting!
Just thinking aloud here. My gear head mill is no different to others in that it sounds absolutely terrible. Clunkety clunk clunk. Everything is in order so I know it's not going to die and I have since replaced the spindle bearings so they are OK which is the business end. BUT I find the terrible sound a big distraction when I'm machining. I have removed the quill and it still makes the same noise so it's not the quill so it can only be the cheap Chinese bearings or the poorly formed/meshed gears. So replacing the bearings may fixed but also i'm thinking that instead of using the ZZ bearings with the metal shields I'm using the RS which tend to have a little more friction. I'm hoping that they may reduce the backlash in operation..... Guess we will see.
Simon
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19th Oct 2012, 04:30 PM #48Most Valued Member
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Simon,
Chinese gears are not wonderful things - well not on lathes anyway, so mills are probably no different.
Bad bearings that still have lubrication normally "rumble" rather than "clunk", so if was me I'd be looking at the gears for any tight or misaligned mesh problems.
Unfortunately things like that are not easily fixed.
You can make your own (spur) gears, I've done it quite a few times, and using alloy will make them run much quieter.
Cheers
Rob
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19th Oct 2012, 04:44 PM #49Cba
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Simon, it is not the bearings. Good machine tools (Chinese or not) use hardened and precision ground gears, about the sort of quality that you would expect in a car gear box, and these are as quite as you would expect in a car or bike. Lowest cost Chinese machine tools often use soft cast iron gears (cast iron as in recycled soup cans) that are not even de-burred and have never seen a grinding wheel. To make matters worse, the center hole is not at the center of the tooth, so the whole gear wobbles aroound the center. To compensate for this, the gear spacing is designed for excessive clearance.... You only ever get what you pay for, even the Chinese are not prepared anymore to work for peanuts. That is why I say, if you do not want to pay for quality, then better buy a lathe or mill with belt drive. You can always fix or improve on a not-so-well made belt drive head with little more than home shop means - it is much much harder to fix or improve a badly made geared head. Chris
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19th Oct 2012, 05:23 PM #50Most Valued Member
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Thanks rob & chris. Luckily my chinese lathe is in total contrast to mu mill. It sounds quite nice when in operation. Mind you the morton style gearbox is a little loud but that's partly my fault from insufficient lubrication. WRT the mill, i was going to change to a belt until chris pointed out (in another thread) that i would be expecting too much for it to get the range of speeds that i want with a single gear ratio. So im still stuck with the dodgy noisey gearbox! I bought what i could both afford and justify, but that didn't mean im guarenteed to be happy with it! Simon
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19th Oct 2012, 05:52 PM #51
Hi Simon,
You could always drain the box and lap all the gears. Just add lapping paste and run it through the speeds. The other option would be to make a few sacrificial ally or plastic gears. All you have to do is replace the one drive gear that is always driving or driven and the noise should subside. If you make enough gears you just replace them as they wear out.1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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19th Oct 2012, 06:47 PM #52Most Valued Member
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Lap the gears hey? I got a lapping kit. Think id be to scared to try that! I don't have a rotary table (yet) so its not within my capacity to make gears at this stage. You can talk me into lapping of gears though...... i better do some research! Simon
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