Delta-Rockwell 1 x 42 Grinder/Sander 31-35x -- Pulleys

Delta-Rockwell 1 x 42 Grinder/Sander Pulleys/Wheels.  These fit the 31-350 & 31-351 models.

• Drive Pulley - PN: 926-11-991-9441

  • Rockwell 31-351 Drive Wheel NoTire v6

  • This is printed as one part, I printed with PLA, 90% infill, supports everywhere, set screw hole to the top. 

  • Then tap the set screw hole with 5/16-18 tap. (I did not run the tap all the way through (a bit of trial and error) so that it would self-lock as it came close to contacting the shaft.)

• Large (Top) Pulley - PN: 406-04-406-002  (Original one came with shaft and bearing, you will have to move from old part)

  • Rockwell 31-351 Large Idler NoTire (split) v5

  • This prints as two halves, I printed with PLA, 90% infill 

  • Installed new Fafnir 203PP bearing.

  • Glued the two halves together with acrylic glue (Weld-On / SCIGRIP 3)

• Idler Pulley (Small) - 926-11-991-9440 (Original one came with bearing, you will have to add/move)

  • Rockwell 31-351 Small Idler NoTire (half) v2

  • Prints 2 of these as model is just one half, I printed with ABS, 90% infill. 

  • I used ABS as these spin fast and the bearings get fairly warm, so I did not want any deformation to occur from the heat.  

  • Installed new Fafnir 203PP bearing.

  • Glued the two halves together with cyanoacrylate glue.

Bearing Note:  The large pulley and idler pulleys use the same bearing.   I replaced with Fafnir 203PP bearings as I already had a bunch of them.  They are equivalent to what was originally in it a Triad 203 K.  Which are 17 mm bore, 40 mm outer diameter, and 12 mm width.  And if you run the math on the speed of the fastest spinning pulleys, the small idler, they will spin around 7700RPM.  And the Fafnir is rated for 10,000RPM.  

Modified to work without rubber tires.  Enlarged diameter of pulleys (wheels) to compensate for no rubber/tire on the outside.  Adjusted/added crown on the pulleys so the belt tracks.  Adjusted drive pulley inner hole for tighter fit on drive shaft.  Added a bit more space for bearings on the large idler pulley.

Thanks a bunch to the original creator for designing these and posting the F360 files.  That saved me a ton of time having to build from scratch.  The core design was excellent and made it easy for me to make the modifications.