Thanks for the updates Steve. Best wishes and a speedy recovery.
-RC
Thanks for the updates Steve. Best wishes and a speedy recovery.
-RC
Steve - I know it's been a while but thanks for posting your impressions. It seems clear that the belt reduction upgrade is the clear path vs. the motor upgrade alone. Is anyone aware of plans, kits, or assembled boxes for sale for us 911 motor owners?
Andrew…
As far as I know, Talking with Mike Richards or buying Dave Rosenbleeths plans are still the best options…
SG
I may have another option. Belt reduction units for the PRT similar to those shown in the pics below. Prices as follows:
X1, X2 & Y gearbox on PRT bracket. (requires drilling an additional hole for stability)
For NEMA 23 nongeared motors (3/8 shaft): $275 ea with 350 ozin motor: $400
For NEMA 34 nongeared motors (1/2 Shaft): $300 ea with 600 ozin motor: $450
For AS911 NEMA34 nongeared motors (14mm shaft): $350 each
Z axis (non swivel mount) reduction box for R&P: $300 with motor add as above
Z axis AS911 (non swivel mount) reduction box for R&P: $350
Z axis ballscrew assembly with mount kit: $400 with motor: $550 (standard Z) Extended add $75
Prices assume purchase of 4 units minimum. Single price add $100. Lead time 3-4 weeks, as they are made to order.
Ratio is 3:1 (standard) for 4:1 add $25 per unit
For more info contact: caseworxmfg (at) gmail (dot) com
PRT swivel reduction units are similar, but not exact to versions shown!! Current version uses bushed 3/8" aluminum in lieu of steel swivel plate.
Gary Campbell
GCnC Control
GCnC411(at)gmail(dot)com
Servo Controller Upgrades
http://www.youtube.com/user/Islaww1
"We can not solve our problems with the same level of thinking that created them"
— Albert Einstein
I've had a number of inquiries and sales (thanks guys) regarding the belt reduction units for the direct drive PRT Alpha with ASM911 motors. Yes they are available, here are the specs and prices:
Units are $400 USD each in groups of 4. They are constructed from billet 6061 aluminum with pressed in ABEC3 sealed bearings and have all keyed shafts. Reduction ratio is 4:1 (only) using HTD 15mm wide belt. All hardware, pulleys, belts and 24t pinion gears are included. There is also the option to add a second support bolt in a provided slot if your application requires it. All components are cut on my CNC Bridgeport Mill. Z product is available to fit most every version of the PRT Z assembly, including the new style Retro Z. Custom configurations are available.
Torque is 3.3 times that of the original with 20t pinion. Resulting unit value is ~2122 steps per inch.
Units ship will full instructions and an "SBD" file with new unit values installed, ready for a few clicks to import.
For more info email: GCnC411@gmail.com
Here are a few pics:
Gary Campbell
GCnC Control
GCnC411(at)gmail(dot)com
Servo Controller Upgrades
http://www.youtube.com/user/Islaww1
"We can not solve our problems with the same level of thinking that created them"
— Albert Einstein
Those reduction units look great Gary. I am a little confused however concerning the comparison between these 4:1 belt reducers and the 7.2:1 tapered hob gearbox motors from Vexta. Would the resolution not be almost double with the 7.2's compared to the 4:1's?
Jon...
Simple answer no. Do your homework. Remember that resolution is what you set it at. Also remember those are different motors with different drives with 20 and 30 tooth pinions. Also remember that cut quality is a combination of speed, resolution, torque (the ability to hold position at microstepped levels) and backlash.
Each and every one of those is changed by resolution settings, reduction ratio, pinion size and motor torque. Combinations are developed are always a compromise. Laws of physics, when one spec is increased, most certainly another will decrease.
Gary Campbell
GCnC Control
GCnC411(at)gmail(dot)com
Servo Controller Upgrades
http://www.youtube.com/user/Islaww1
"We can not solve our problems with the same level of thinking that created them"
— Albert Einstein
Gary, I'm trying to do my homework here by understanding all of this. I suppose that the reason shopbot used the 30 tooth gears was to give the bot a smoother action on the linear rack. Do you know if it's worth it to put the 20 tooth pinions on the 7.2 motors? If I made a 2:1 reduction belt box and added it to the 7.2 gear head would there be more backlash than resolution gain? Would the communication and software be able to handle that? I have the newest control card in my box.
Jon...
Your idea of homework and mine are different, I think. So between myself and a couple of friends I have access to uncounted hundreds of hours with motors and racks and pinions, dial indicators, torque meters, even a small hydraulic stepper dyno. That's homework. Finding out what someone else "thinks" in the internet is not.
I assume that the 30 tooth gears returned the best combo of speed, torque and cut quality within the range they were looking for. Actually this is true.
I know for a fact that there will be an inverse gain using 20T pinions on the 7.2TH ASM's.
Adding 2:1 reduction will not improve anything, except in the most rare of cases. You want these motors to stay in their torque range to be able to hold position on angular and radiused cuts.
The backlash, 6 arc minutes or 1/10 of a degree is inherent with those 7.2 gearmotors. 1.5" pinion * pi / 360 /10 is seldom the cause of issues. Pinion wear, wear from use and maladjustment are far more likely to cause issues.
Buy a set of the new AR series motors and drives and throw them on.
Gary Campbell
GCnC Control
GCnC411(at)gmail(dot)com
Servo Controller Upgrades
http://www.youtube.com/user/Islaww1
"We can not solve our problems with the same level of thinking that created them"
— Albert Einstein