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Spindle Speed for American Radial Arm Drill (4ft)

Dr. Hillbilly

Aluminum
Joined
Dec 6, 2019
Location
Oregonia, Ohio
I also acquired a Radial Arm Drill from a line-shaft shop, without main or counter-shaft pulleys so rpm is unknown. It appears to be similar to the 1919 model so the original spindle speed was probably 300 rpm max. However as high-speed tools became available the max. spindle rpm soared to 1200 rpm and then to 2000 rpm in the following years. Does anyone know if I can select my counter-shaft pulley diameters for the higher RPM without abusing the spindle?
 

sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
What can you tell use about the type of spindle bearings and their lubrication system (if any) in your drill? That's going to strongly influence the answer to "Can I run this at the higher speeds".
 

Dr. Hillbilly

Aluminum
Joined
Dec 6, 2019
Location
Oregonia, Ohio
What can you tell use about the type of spindle bearings and their lubrication system (if any) in your drill? That's going to strongly influence the answer to "Can I run this at the higher speeds".

Bronze bushings.
The illustrations of the bushings look the same in publications from 1919 to 1928 (300 rpm to 2000 rpm), but they may just be schematic.
 

Jim Christie

Titanium
Joined
Mar 14, 2007
Location
L'Orignal, Ontario Canada
If you increase the speed of the machine the ability of the spindle bearings to take it may not be the only thing you need to consider.
If there are power feed components or back gearing for the spindle involved they also may have to be able to take the extra speed or may be quite noisy if you can't disengage them for high speed running.
Jim
 

Dr. Hillbilly

Aluminum
Joined
Dec 6, 2019
Location
Oregonia, Ohio
See the 1915 Efficiency Bulletin - it refers to high speed ball bearing radials as being available. maybe you got lucky. The fact that it mentioned ball bearing would seem to eliminate those not equipped with high speed systems from being converted

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Have fun

A wealth of information!
How will I tell if I got lucky?
The lube system for rolling elements must be different than for bushings?
Use a sensitive accelerometer and rotate the spindle, listening for ball pass frequencies?
Observing how much lube leaks?
 








 
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