# Atlas 10F 24... motor RPM and HP verification ..



## tawas23 (Aug 23, 2014)

Wondering if someone could let me know the HP... I believe 1/3 to 1/8...  and RPMS of the motor that should be on this beauty Atlas 10F 24 with Babbit bearings ..


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## kd4gij (Aug 23, 2014)

Up to 1/2 hp 1750rpm or thereabouts.


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## pdentrem (Aug 23, 2014)

My Timken version had a 1/2 hp motor, but it was not original. The lathe came out of a high school.
The motor rpm was the standard 17xx as found on most motors today.
Pierre


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## tawas23 (Aug 23, 2014)

thanks for the input

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 ...One more question just read that my lathe 10F 24  rear gear drive max turning speed is 345 ...thought it was much higher ...can someone tell me if the speed of this lathe is 345 or can it turn any higher ?????MY bad I found out my problem ...


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## wa5cab (Aug 24, 2014)

Tawas,

Original motor recommendations for the 10" was 1/3 or 1/2 HP, 1725 to 1750 RPM.

The speed range of the Atlas 10" and 12" machines when fitted with a nominal 1725 RPM motor is 28 to 2072 RPM.  The speed range in direct drive is 164 to 2072.  With back gears engaged, the speed range is 28 to 345 RPM.  For most turning work on a 10" or 12", you wouldn't use back gears.  However, it depends upon the diameter of the workpiece and the cutter speed you need for the material that you are working.  For a table of cutting speeds versus diameter versus RPM, look in the MOLO around page 47 to 49, depending upon which edition you have.  A couple of pages earlier, you will find a chart of various types of steel and other materials versus recommended cutting speeds with HSS (High Speed Steel) cutters.  

Robert D.


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## tawas23 (Aug 24, 2014)

Let me understand something better :thinking: ...are you saying I dont use the back gears when turning ..I thought the back gears always had to be engaged..what are the back gears for ??????

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Pic of my Atlas 10F 24

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another pic

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Lathe pics

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1 more

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Thanks to this site and help from members its up and running like a champ ..thanks again to all thats helped me with this beauty :thanks:


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## wa5cab (Aug 24, 2014)

The back gears are a compact way to slow the spindle speed down by, in this case, a factor of 6 to 1.  Doing the same thing in a 2-stage belt drive system would be impractical because the largest pulleys on the spindle and on the left side of the countershaft (motor belt) would be huge.  Think of it as akin to the two-speed transfer cases in most 4X4 and 6X6 motor vehicles.  If you want to go fast, you put the transfer case in high range (usually 1:1) and use the main gearbox for shifting.  If you want to crawl along slowly, you put the transfer case in low range and then again use the main gearbox to "fine tune".  

Atlas had a try at doing it all with belts in the early 9" lathe.  They called the system the "compound drive".  Apparently it worked better in theory than in practice as after a couple of years they came out with a 9" without the compound drive.  And shortly after that, scaled it up to 10", which in two or three years became the machine that you have.  For a few years in the mid 30's they and Sears sold versions of the 10" and 12" without the back gears.  But they dropped those by 1940.

Robert D.


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## tawas23 (Aug 24, 2014)

Wow Yikes...... to think I have been running this lathe in all speeds with the back gear engaged..my bad ..I did this because the belt seemed to slip without the back gears engaged ...I better go check my belt tension or find out why my belt slips when the back gears are not engaged ....what year do you think my lathe is approximately????


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## wa5cab (Aug 24, 2014)

The Atlas 10F came out circa 1939 (maybe late 1938).  The babbit bearing headstock was I think offered up to about 1945.  On a babbit bearing model, without a serial number that's as close an estimate as can be given.

RD


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## tawas23 (Aug 24, 2014)

the other number I found are 9-95A in rear by gear cover and inside gear cover 10F 24 other than that no more numbers exist ..Also I tried running it without back gears engaged and I can stop the chuck with my hand and some pressure ..belts are tight and new ...the counter shaft belt slips if back gears are not engaged ...any ideas???


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## JOEZ (Aug 24, 2014)

The reason you can stop your chuck with your hand is ,there is a pin in the big gear on the spindle shaft that needs to be engaged.

Also I noticed if you put a smaller pulley on you motor it would slow it down a lot.


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## tawas23 (Aug 24, 2014)

Finally found out on how to use the BULL gear and pin with or without the back gears.... wow opened up a whole different lathe...now this lathe is running way better than before ..my bull gear pin was out to far not giving me correct speeds and I had to use the back gears to do anything..thats way my questions were about motor size/speed/feed rate etc..now I can run at speed and feeds that I could not get before... very important for new lathe owners of these sizes to know how the BULL gear and bull gear pin works ..thanks again to all that helped me ..


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## wa5cab (Aug 24, 2014)

The usual question that we get from new owners is why the belts slip and the spindle won't turn if they engage the back gears.  The answer, of course, is to pull out the pin and read the manual.    Incidentally, the pin should not come out.

You also need the correct size 2-step motor pulley.  The two diameters (OD) are approximately 1.930" and 4.390".  As shown, you have an 8-speed machine.  If the motor pulley OD is close to 4.390". then the 8 speeds that you can get are the high numbers of each pair.  There is a motor pulley drawing in Downloads.  Also note that when you calculate the pulley ratios, you use the pitch diameter, not the outside diameter.  The PD is roughly the outside diameter of the belt when in the pulley (which should be slightly less than the pulley OD) minus the belt height or thickness.

Robert D.


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## wa5cab (Aug 24, 2014)

Those are both part numbers.  If you look, you will find similar numbers on most parts on the machine that were made from castings and not on any that weren't.  

Look on top of the right end of the front way close to where the tailstock runs.  Most pre-1957 machines have the serial number there and not on the nameplate.  
Robert D.



tawas23 said:


> the other number I found are 9-95A in rear by gear cover and inside gear cover 10F 24 other than that no more numbers exist ..


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## tawas23 (Aug 25, 2014)

My motor pulley measures same as drawing and in post.. thats good to know  ..as for my bull pin coming out I had to turn it and pull to get it out ..it stays in now I know how to use it .. looking for numbers next ..thanks


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