Speed/RPM/SFM Slide Rule

[whydontu]

Saw this Feed and Speed slide rule and decided I want to make one. Probably will be engraved aluminum sheet. I haven't worked out the details yet but I've cobbled up the scales. The beauty of a slide rule is it always works, never needs recharging, and can provide an answer starting from any two variables.

I'm only making the Speed section, all my machines are manual so chip load and cubic inch calculations are irrelevant.

Wild ass thought, engrave the side rule scales on the back of a cheap brass caliper?

DXF file at https://www.dropbox.com/scl/fi/d241...ey=m5eq9w9q4n9nspjyn89ro73sz&st=1rsrywj5&dl=0

I'm picturing a slide rule with a chart of materials vs. typical SFM values. My electronic SFM calculators work, but this will be cooler and doesn't need a battery.

 

[David]

Very cool

 

[jorogi]

I'll take one

 

[Dan Dubeau]

I have the same one in the OP. Don't use it much anymore, but I have a thing for those old slide calculators, and have a bunch of them for various things.

I started using it again more at home as I'm doing more manual machining, and needed to re calibrate myself from the CNC speeds and feeds I'd grown accustomed to at work.

IMO I think everybody should start with one of these as they really show the relationship between speed, feed, chipload and SFM and how changing one, affects the others. Using one, even for a short bit should really drive home how these numbers relate, and help develop a better understanding of what they mean as opposed to plugging #'s into a speed and feed calculator and just blindly trusting the results.

 

[Susquatch]

Count me in too!

 

[whydontu]

Did some more layout work. Here's a link to the DXF file for this version:

Dropbox

www.dropbox.com

The top rectangle is the slider, the bottom is the frame. The rectangle below the arrow is cut out as the window to view the slider.

I'm picturing this as five pieces of aluminum sheet, slider and frame engraved as above, a blank backing piece the same dimensions as the frame, with two spacers to located the slider in proper alignment to the frame. I can't draw 3d stuff, so you'll need to make your brain wrap around my crappy description.

And no, it's not accurate to seven decimal places. Scale is laid out on a 0.010" x 0.010" grid, no point in being a fussbudget about this. Running a cutter at 345 RPM instead of 350 isn't going to ruin anything.

I might get super ambitious and engrave the blank backing piece with something useful like a tap drill chart or a number drill to decimal chart. Maybe even more info on the blank area of the slider, since it's easy enough to pull it out of the frame.

Next step is a prototype in ABS using my laser engraver. Laser engraver can scale from DXF and burn lines less than 0.002" wide.