- Joined
- Apr 11, 2014
- Messages
- 23
Hello peoples,
I'm new to metalworking. My occupation is woodworking which using various related equipment that kinda motivated me to learn more of the machining world. Like why some operations/tools, equipment are more accurate than others and what can improve them. Repairs and mods also led me to the services of a machinist from time to time, also.
Currently working on my modest 4'x8' cnc used for sheet stock processing. Ive had 3/1 gear ratio XL timing belt boxes built in the past to replace the machines original stepper motors to more powerful (more torque over broader range of rpm's) stepper motors.
Came across the ClearPath servo motors and decided to upgrade to an appropriate sized motor for the 3 axis. Figured I would also fabricate new belt drive gear boxes while I'm at it to replace the older ones I originally had built. Kind of a botched job on that build from the guy I had building them. Needed to be built out of Aluminum rather than steel. Was built with 1/2" steel bar stock instead. A few other problems with the design but I cut my losses and ran with what was fabricated thinking I'd limp along and replace them eventually. That was 10 years ago...
Now that I'm upgrading stepper motors to servo's I figured it was a good time to build new belt drive boxes to replace the heavy arsed existing one's. Here's where It's at so far:
The two 'plates' have been cut out of 1/2" MDF on the 4x8 for prototyping> I will eventually cutting the plates put of 1/2" 6068 aluminum plate stock using same 4x8 cnc these boxes will be upgrading. Gears are 60T & 20T aluminum XL timing gears. The larger 60T gear will be mounted to a 1/2" diameter shafts' end that will extend thru the plate opposite the one the servo is bolted to. The pinion gear attached engages the racks on the cnc axis' racks. Shaft is supported by two bearings that mill be installed in bearing pockets milled into both plates (sides facing each other).
Plates are separated by threaded stand offs that are 5/8" diameter and recessed about 3/32' into pockets milled into the plates. Bolts will be replaced with flat head machine screws. The plates thru holes for the screws will have to be countersunk on the opposite sides of the stand off pockets to allow them to be flush to the plate surface. I Turned the stand off's on my Southbend 9 (I scrounged the Southbend a couple of years ago in anticipation of this project. Thanks to all of the good folks over at the Southbend forum for helping me get that up and running!!!).
That's where I'm at on this project but I have a couple questions for getting it completed:
The 60T gears' shaft... The CNC's rack pinion gear, that will be getting attached to the end of it, is a 1/2" bore. I've ordered all new 20T, 60T timing gears. 20T with 1/2" bores and fit the servo motors' 1/2" shaft nice and snug. 60T gears were a little harder to come by with 1/2" bores so I decided I would order them in the more common 12mm bores and enlarge them to 1/2" diameter (HEY, i've got a lathe now!). Would it be better to get a 1/2" reamer and ream them out or turn them on the lathe? Would reaming be accurate enough? Would turning be better? If so, it seems like it may be hard to get them accurately mounted in a 4 jaw to ensure concentricity. The outer diameter gear teeth look like they would be a challenge to get a good indicator reading from. Maybe put a wide foot on the indicator and wiggle a selected tooth back and forth under it to get the maximum reading? Repeat with 3 other teeth selected at 90 degree intervals from the first? A better look at the 60T gear:
60T gears' shaft... Is there a particular steel (very ignorant here) that would be better than others for this application. lengths are apx. 5". Heaviest use would be the X (96") axis. The CNC's gantry runs along that axis with 2 motors engaging racks opposite one another, with one motor reversed 180 so they both spin in the same direction on opposite sides of the machine. The gantry's total weight I would guess to be over 300 lbs.
I's there a source for reliably accurate steel shaft that would be good for this application?
Any advice for those two questions would be appreciated.
Thanks Tim
I'm new to metalworking. My occupation is woodworking which using various related equipment that kinda motivated me to learn more of the machining world. Like why some operations/tools, equipment are more accurate than others and what can improve them. Repairs and mods also led me to the services of a machinist from time to time, also.
Currently working on my modest 4'x8' cnc used for sheet stock processing. Ive had 3/1 gear ratio XL timing belt boxes built in the past to replace the machines original stepper motors to more powerful (more torque over broader range of rpm's) stepper motors.
Came across the ClearPath servo motors and decided to upgrade to an appropriate sized motor for the 3 axis. Figured I would also fabricate new belt drive gear boxes while I'm at it to replace the older ones I originally had built. Kind of a botched job on that build from the guy I had building them. Needed to be built out of Aluminum rather than steel. Was built with 1/2" steel bar stock instead. A few other problems with the design but I cut my losses and ran with what was fabricated thinking I'd limp along and replace them eventually. That was 10 years ago...
Now that I'm upgrading stepper motors to servo's I figured it was a good time to build new belt drive boxes to replace the heavy arsed existing one's. Here's where It's at so far:
The two 'plates' have been cut out of 1/2" MDF on the 4x8 for prototyping> I will eventually cutting the plates put of 1/2" 6068 aluminum plate stock using same 4x8 cnc these boxes will be upgrading. Gears are 60T & 20T aluminum XL timing gears. The larger 60T gear will be mounted to a 1/2" diameter shafts' end that will extend thru the plate opposite the one the servo is bolted to. The pinion gear attached engages the racks on the cnc axis' racks. Shaft is supported by two bearings that mill be installed in bearing pockets milled into both plates (sides facing each other).
Plates are separated by threaded stand offs that are 5/8" diameter and recessed about 3/32' into pockets milled into the plates. Bolts will be replaced with flat head machine screws. The plates thru holes for the screws will have to be countersunk on the opposite sides of the stand off pockets to allow them to be flush to the plate surface. I Turned the stand off's on my Southbend 9 (I scrounged the Southbend a couple of years ago in anticipation of this project. Thanks to all of the good folks over at the Southbend forum for helping me get that up and running!!!).
That's where I'm at on this project but I have a couple questions for getting it completed:
The 60T gears' shaft... The CNC's rack pinion gear, that will be getting attached to the end of it, is a 1/2" bore. I've ordered all new 20T, 60T timing gears. 20T with 1/2" bores and fit the servo motors' 1/2" shaft nice and snug. 60T gears were a little harder to come by with 1/2" bores so I decided I would order them in the more common 12mm bores and enlarge them to 1/2" diameter (HEY, i've got a lathe now!). Would it be better to get a 1/2" reamer and ream them out or turn them on the lathe? Would reaming be accurate enough? Would turning be better? If so, it seems like it may be hard to get them accurately mounted in a 4 jaw to ensure concentricity. The outer diameter gear teeth look like they would be a challenge to get a good indicator reading from. Maybe put a wide foot on the indicator and wiggle a selected tooth back and forth under it to get the maximum reading? Repeat with 3 other teeth selected at 90 degree intervals from the first? A better look at the 60T gear:
60T gears' shaft... Is there a particular steel (very ignorant here) that would be better than others for this application. lengths are apx. 5". Heaviest use would be the X (96") axis. The CNC's gantry runs along that axis with 2 motors engaging racks opposite one another, with one motor reversed 180 so they both spin in the same direction on opposite sides of the machine. The gantry's total weight I would guess to be over 300 lbs.
I's there a source for reliably accurate steel shaft that would be good for this application?
Any advice for those two questions would be appreciated.
Thanks Tim
