# Slowing Down An Atlas



## cdhknives (Mar 4, 2015)

Say I wanted to cut the slowest leadscrew speed down even slower...for feedrates useful in drilling and milling stainless steel with a drill bit in a boring toolpost and milling with the mill attachment.  The power cross slide is particularly fast for facing operations as well.  I have a QC gear box already, so do the correct gears exist for something like 1/2 or 1/4 speeds (to simplify threading, an even multiple is desired) to the leadscrew?  If I could cut it in half or 1/4, threading would still be possible by multiplying the required thread by 2 or 4 as applicable to find the correct selection on the QC levers.


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## pebbleworm (Mar 4, 2015)

A hand crank?  A useful gadget I found out about when I was using a Unimat.  Lots of plans and drawings are out there for different machines.  It wouldn't fly in a production shop, but as Mr. Sparey says in the Amateur's Lathe, a lot of us are using a too small machine to the last gasp of its' capabilities.  You could also change the motor and jackshaft pulley sizes.


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## bill stupak (Mar 4, 2015)

Here is a link to all the speeds available.
www.machinistweb.com/forum/showthread.php?t=2711 
Scroll down to Rob's reply. I plan on doing the same thing and am shooting for .002' per rev

Bill


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## cdhknives (Mar 4, 2015)

Changing the motor pulleys would not help, I want to change the spindle/leadscrew ratio to 1/2 to 1/4 the current slowest rate so I can set up autofeed drilling with 2 hands free to pump oil and air into the hole.  This stuff work hardens so fast I hate to stop a cut as restarting means breaking through a hardened skin...at least that is what it feels like.


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## cdhknives (Mar 4, 2015)

Exactly Bill, the slowest feedrate on the standard QC gear box is like .0042"/rev...fine for turning but too fast for boring and facing.


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## VSAncona (Mar 5, 2015)

If you can find a copy of the original Atlas quick change gearbox manual, it has pages of charts with the gears needed for different feed rates. I swapped out a couple gears on mine and got the feed rate down to .00144".


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## yendor (Mar 5, 2015)

There is a copy of the QCGB Gear Setup Manual in the Thread Link posted above.

On the LAST Line of the Threading Chart it lists the combinations required for a .001 Feed Rate which is the equivalent of 1000 TPI.

The PDF Link is on the 2nd page of the linked thread.


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## outsider347 (Mar 5, 2015)

I can t get into the link to find the slowdown gear combo
Available anywhere else?
tks
ed


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## Rob (Mar 6, 2015)

You can find it here. 

http://www.flywheelmachinetools.com/Data/Atlas10QCgearsetups.pdf


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## cdhknives (Mar 6, 2015)

It looks like the sliding gear [IN] halves the QCGB already...quick and easy!  Thanks!  Now to look for change gears...


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## cdhknives (Mar 6, 2015)

Duh...it doubles the leadscrew speed.  Halving the threads per inch doubles the speed the leadscrew advances the carriage.  I gotta stop and let my brain catch up before I type sometimes...


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## wa5cab (Mar 7, 2015)

Heh heh.


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