I was searching around on eBay and came across an interesting little trunnion table, link below. I had seen similar units, but they all used belt drive reductions, which from experience will not have enough reduction, and will likely be chatter with any real cutting, not to mention the belt is exposed. This unit however uses a harmonic drive to get a 50:1 reduction, with essentially zero detectable backlash. on top of that, it actually back drives the stepper motor. Harmonic drives are also sometimes called wave strain drives or flex spline drives. Anyways, the trunnion uses a couple of nema 23 steppers, and the holding torque is fantastic, even with a cheap stepper driver. For simplicity I'm using an arduino based controller that runs grbl 1.1f, and a couple of 5-30v inductive switches, links below. The controller can be controlled by sending gcode over the rx and tx pins, aka rs-232. The trunnion unit itself is very beefy for what it is, and has what look to be waterproof seals around all the bearings, so with a bit more sealing on the motors it can probably handle coolant usage.
I was looking on ebay and it looks like there is a smaller single shear unit for about $550, I might buy one of those for my plasma table haha.
I use fusion 360 for all of my CAM, and one of the big draws is it can do multiaxis toolpaths. The second biggest draw, for me at least, is the post processors can be edited. The third thing being the new machine simulation, I was able to use the haas provided model for the CM-1(we have an OM2 at work, but its the same mechanically), and modeled up the trunnion and configured it to behave correctly to simulate indexing.
I modified The pre-ngc 5 axis post and configured it to work with the way I have the trunnion mounted in the machine, then I also modified the output of a and b gcodes for indexing operations appear as shown below.
Standard Post: G0 A0. B90.
Eventual Modified Post: DPRNT[G0 A0. B90.]
Im avoiding altering the grbl firmware for now, just editing parameters, so the gcodes the haas will be sending over serial will actually be X and Z codes for the A and B axiis. Ultimately its not necessary to change the firmware to accept a and b codes, however I want to make it right so its more readable, and there's a few other things I want to change as well.
Current modified post: DPRNT[G0 X0. Z90.]
Things still to work out:
I've done some reading on the Haas DPRNT command, and its very limited. Only A-Z, and +, -, can be put out. The grbl controller has special commands the use the $ symbol, for example to home, or send out positional data over serial. If I edit the firmware I can probably change that and use standard gcodes instead like g28 and g102.
I hooked everything up and the trunnion didn't move(womp womp), so I'm in the process of diagnosing why that is, starting with testing the output of the haas itself. I had one of the pixie wizards hook up the output to his signal analyzer, and he said it was basically outputting noise, so I'm not sure if there's a parameter that needs to be changed, but the control seemed happy with the code I had input in MDI and I made sure the macro parameter was enabled. The code: DPRNT[G0 X90 Z0].
The other issue is the controller doesn't have specific pin or button to home the axiis, for now I have an offline controller, and with it I can run programs from an sd card, i have a program to home the machine using the illegal $H command lol.
Link to buy on ebay, although I got mine through aliexpress for cheaper. CNC Rotary axis Harmonic Gearbox Dividing Head 5th 4th Axis 50:1 reduction ratio | eBay
single shear head: CNC 4th 5th A B Rotary Axis Harmonic Drive Reducer Dividing Head SpeedRatio 50:1 | eBay
Strain wave gearing - Wikipedia
3 Axis GRBL 1.1f USB Port CNC Engraving Machine Control Board CNC Router Engraver Milling Machine Controller board - - Amazon.com
Amazon.com: XJS DC 4.8-30V 500mA NPN NO 3-Wire 4mm Inductive Proximity Sensor Switch SN04-N : Industrial & Scientific
I was looking on ebay and it looks like there is a smaller single shear unit for about $550, I might buy one of those for my plasma table haha.
I use fusion 360 for all of my CAM, and one of the big draws is it can do multiaxis toolpaths. The second biggest draw, for me at least, is the post processors can be edited. The third thing being the new machine simulation, I was able to use the haas provided model for the CM-1(we have an OM2 at work, but its the same mechanically), and modeled up the trunnion and configured it to behave correctly to simulate indexing.
I modified The pre-ngc 5 axis post and configured it to work with the way I have the trunnion mounted in the machine, then I also modified the output of a and b gcodes for indexing operations appear as shown below.
Standard Post: G0 A0. B90.
Eventual Modified Post: DPRNT[G0 A0. B90.]
Im avoiding altering the grbl firmware for now, just editing parameters, so the gcodes the haas will be sending over serial will actually be X and Z codes for the A and B axiis. Ultimately its not necessary to change the firmware to accept a and b codes, however I want to make it right so its more readable, and there's a few other things I want to change as well.
Current modified post: DPRNT[G0 X0. Z90.]
Things still to work out:
I've done some reading on the Haas DPRNT command, and its very limited. Only A-Z, and +, -, can be put out. The grbl controller has special commands the use the $ symbol, for example to home, or send out positional data over serial. If I edit the firmware I can probably change that and use standard gcodes instead like g28 and g102.
I hooked everything up and the trunnion didn't move(womp womp), so I'm in the process of diagnosing why that is, starting with testing the output of the haas itself. I had one of the pixie wizards hook up the output to his signal analyzer, and he said it was basically outputting noise, so I'm not sure if there's a parameter that needs to be changed, but the control seemed happy with the code I had input in MDI and I made sure the macro parameter was enabled. The code: DPRNT[G0 X90 Z0].
The other issue is the controller doesn't have specific pin or button to home the axiis, for now I have an offline controller, and with it I can run programs from an sd card, i have a program to home the machine using the illegal $H command lol.
Link to buy on ebay, although I got mine through aliexpress for cheaper. CNC Rotary axis Harmonic Gearbox Dividing Head 5th 4th Axis 50:1 reduction ratio | eBay
single shear head: CNC 4th 5th A B Rotary Axis Harmonic Drive Reducer Dividing Head SpeedRatio 50:1 | eBay
Strain wave gearing - Wikipedia
3 Axis GRBL 1.1f USB Port CNC Engraving Machine Control Board CNC Router Engraver Milling Machine Controller board - - Amazon.com
Amazon.com: XJS DC 4.8-30V 500mA NPN NO 3-Wire 4mm Inductive Proximity Sensor Switch SN04-N : Industrial & Scientific
