Conference 44.392::eng_in_miniature

>>    And could somebody once again reassure me that running the straight-
>>    cut gears at 1000 rpms is an okay thing to do? :-) It sounds fine
>>    (I redid all the bushings back there so the gears are sitting
>>    correctly) but VERY busy!
    
    Sure, it's okay Charlie. You've got a heavy cast iron belt and gear
    guard on the Logan.  If the gears blow up, there's very little risk of
    getting hurt.  ;-)))))

    Hello again. What is the max rpm you've run your lathe at under
    power feed? Just curious..... Those S7's go about 2K right? Ever
    run it that fast under powerfeed?
    
    Thanks,
    Charlie

<                     <<< Note 166.2 by TALLIS::GREENMAN >>>
<                         -< max rpm under powerfeed? >-
<
<    Hello again. What is the max rpm you've run your lathe at under
<    power feed? Just curious..... Those S7's go about 2K right? Ever
<    run it that fast under powerfeed?
<    
<    Thanks,
<    Charlie

I have never not used my power feed because of RPM.
The then again I am almost never on the fast side of the primary pulley
so for me high speed is usually in the 700 RPM range.
Also I haven't done much milling on the lathe since I got a small Clausing.

So - I hear your question - but I can't be much help.

Bye          --+--
Kay R. Fisher  |
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    Okay then, next question.....
    
    What do you use to lubricate your drive gears?
    
    Open gear grease?
    
    Light oil?
    
    I use a bit of 50w on them; just enough to keep them wet.
    
    And again.... any of you running your lathes up much beyond 1000rpm
    in powerfeed? I reread the "owner's manual" for 'a lathe like mine'
    (same spindle/gears/apron/quickchange but about 30 years newer), and
    top rpm is 1800 and it says nothing in there about not (sorry for the
    double negative) using the quickchange.
    
    But I'll tell you, at 1000rpm in powerfeed, it sounds like the M715
    coming down out of the mountains against the engine at 65mph :-)
    
    /Charlie

On behalf of other Myford S7 owners... (??? where are you all???)

Like Kay, I seldom use the "high" range, so generally keep below ~900-1000RPM.
Higher speeds are usually reserved for drilling, but as you rightly point out,
are also useful for milling cutters in the small sizes. From memory (some time
since I have done milling in the lathe) I have probably not used power feed at
the same time.

Yes, the gears are noisy (although the Myford uses Tufnol gears for the first
tumbler gears). I am quite sure that they will stand up to the speeds and loads
being applied. After all, the back gears are the same DP and take much heavier
loads (albeit at lower speeds). I have seen no warnings not to use power feed at
high speeds. I remember Martin Cleeve talking about screwcutting at 1000RPM with
his auto-cutoff, and essentially he was using the same gear setup. Myford do
indicate that back gear should not be used at the two highest speeds, but there
is no need to anyway, as these overlap with the lowest direct speeds.

I use a small dribble of oil whenever I get fed up with the noise. A light
grease is probably better, as oil tends to get flung off. You also have to be
very careful to keep the gears clean (i.e. avoid swarf coming back out of the
spindle) as swarf sticks only too easily to oily gears. My Dore-Westbury uses a
heavy grease on the back gears, as it is fiddly to re-grease and even the thick
grease obviously gets thrown off after a while. Top speeds there are probably
~1000RPM.

- Brian

    Thanks Brian (and Kay). I too have seen no warnings about using
    powerfeed at high rpm. But again, the only time you'd want to do it
    would be with milling and almost nobody does that with "American"
    style (no t-slot cross-slide) lathes.
    
    I have now gotten sort of used to what it sounds like at 1000rpm
    which right now is max speed for the lathe (it has a slow motor). But,
    when I eventually (soon I think) convert the primary drive to poly-v
    belt and a 3-step pulley, I'm going to go for the full range, which is
    up to 1800rpm. I do think I'll hold powerfeed to 1000rpm which ought to
    work okay. I mean how many models were made with ML7's and they top at
    what, 800rpm or something?
    
    Rocol sells an open-gear lubricant and I may try that (in moderation).
    I have read the great GHT (and I think others) who crack on ME's who
    grease their gears, saying a bit of light oil is sufficient. I was also
    quite liberal with the lash and I should probably go back and check
    that with some cigarette paper and shoot for the minimum. (I shimmed
    the rack/pinion to the minimum with good effect I think.)
    
    I did redo all the bushings back there as part of the lathe renovation
    (sp?) and made new (some three and four times!) spindles for everthing.
    It needed it. (If you want a pretty good indication of how "used" a
    used lathe is, reach back and wiggle the stud gear!)
    
    I personally could not imagine firing up the backgears at say 1500rpm!
    Could you imagine what that would sound like!!
    
    Thanks,
    Charlie

    Since (in theory) gears make rolling contact only, you shouldn't
    need much lubricant.  Eliminating most of the backlash ought to 
    help with the noise, I think.  

<                     <<< Note 166.4 by TALLIS::GREENMAN >>>
<
<    Okay then, next question.....
<    
<    What do you use to lubricate your drive gears?
<    
<    Open gear grease?
<    
<    Light oil?
<    
<    I use a bit of 50w on them; just enough to keep them wet.

I use STP on the open gears (about once a month) and on the dead center.

Bye          --+--
Kay R. Fisher  |
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