paulwall wrote: ↑Wed May 27, 2020 10:53 pm
Gary had the same recommendation for me. I opted for the 3421S ELN model, and am going to pair them with 25t pinions to squeeze just a bit more speed out of them. We shall see how that goes. How has the adaptation to the new control software been for you? I assume Gary set the machine up to make the transition nice and easy.
Actually I recommended the 3411S model for all ShopBot PRS models because (IMHO) the others have too much torque for the frames and the SB gravity based V-roller motion system. I wouldn't put on anything stronger unless linear rails are installed. I would also not "gear for speed" on a machine that the success of operation will be determined by motion below 300 ipm for the most part.
There is a possibility of the 3421S working well on the Z if you were not going to replace the spring counterbalance on the Z and do a lot of 3D cutting.
I ran a short experiment this morning to see what happens when using the Teknic Power-4 hub. I powered the hub ON (24VDC), then powered on the motor power supply (75VDC). I manually jogged the X-axis motor to verify motion. Then, after marking the position of the X-axis, I turned off the motor power supply. I turned the X-axis shaft 1/4th turn manually. The Centroidcnc software detected a motor fault (HLFB out of position). I pressed Reset to clear the fault and then turned the motor power supply ON. The X-axis shaft stayed in the same position. It did not return to the pre-power-off position. I thought that was the way it worked when I tested it months ago, but either I didn't write it down or I misplaced my notes.
So, the Power-4 hub keeps the encoder ON, even when power to the motor is turned OFF. (It has a 24VDC power input that is separate from the 75VDC motor power supply input.) The motor sends the proper HLFB signal even when the 75VDC supply is turned OFF. The Acorn will receive the proper HLFB motor fault signal even if the 75VDC supply is off. The operator will know from the motor fault signal that the axis(s) is/are out of position.
Richards wrote: ↑Thu May 28, 2020 8:53 am
I ran a short experiment this morning to see what happens when using the Teknic Power-4 hub. I powered the hub ON (24VDC), then powered on the motor power supply (75VDC). I manually jogged the X-axis motor to verify motion. Then, after marking the position of the X-axis, I turned off the motor power supply. I turned the X-axis shaft 1/4th turn manually. The Centroidcnc software detected a motor fault (HLFB out of position). I pressed Reset to clear the fault and then turned the motor power supply ON. The X-axis shaft stayed in the same position. It did not return to the pre-power-off position. I thought that was the way it worked when I tested it months ago, but either I didn't write it down or I misplaced my notes.
So, the Power-4 hub keeps the encoder ON, even when power to the motor is turned OFF. (It has a 24VDC power input that is separate from the 75VDC motor power supply input.) The motor sends the proper HLFB signal even when the 75VDC supply is turned OFF. The Acorn will receive the proper HLFB motor fault signal even if the 75VDC supply is off. The operator will know from the motor fault signal that the axis(s) is/are out of position.
Which is, if I am correct, the same exact feedback to the controller that we have without the hub, (assuming HLBF is connected) correct?
Gary,
That is correct; however the hub can be connected to two Ipc-5 power supplies and four motors (more if multiple hubs are used). I've made custom cables and I've used stock cables. Crimpers to make good cables are pricey if they are efficient. Of course on a router custom length cables might be needed.
Gary Campbell wrote: ↑Thu May 28, 2020 8:51 am
Actually I recommended the 3411S model for all ShopBot PRS models because (IMHO) the others have too much torque for the frames and the SB gravity based V-roller motion system. I wouldn't put on anything stronger unless linear rails are installed. I would also not "gear for speed" on a machine that the success of operation will be determined by motion below 300 ipm for the most part.
There is a possibility of the 3421S working well on the Z if you were not going to replace the spring counterbalance on the Z and do a lot of 3D cutting.
Well now I'm really questioning my decision! I put my order on pause until I can make more sense of it all. Gary are you of the opinion that downtuning the torque limit through the Clearpath software of a 3421S on X & Y would have no advantage over a 3411S setup without any software limits? From a logic perspective I suppose if you have to cap the torque anyways then you're missing out on the speed capabilities that the 3411S would offer. I remember you mentioned to me earlier that the 3411S already has 3x the torque of the stock PRS Alpha setup now that I mention it.
Richards wrote: ↑Thu May 28, 2020 1:22 pm
Crimpers to make good cables are pricey if they are efficient. Of course on a router custom length cables might be needed.
I've found that the stock (10'-55') cable lengths are seldom "just right" for a professional looking installation. I do have crimpers for the mini-fit jr (data) and sabre (power) connectors. And yes, they are expensive.
Last edited by Gary Campbell on Thu May 28, 2020 8:47 pm, edited 1 time in total.
paulwall wrote: ↑Thu May 28, 2020 2:57 pm
Well now I'm really questioning my decision! I put my order on pause until I can make more sense of it all. Gary are you of the opinion that downtuning the torque limit through the Clearpath software of a 3421S on X & Y would have no advantage over a 3411S setup without any software limits? From a logic perspective I suppose if you have to cap the torque anyways then you're missing out on the speed capabilities that the 3411S would offer. I remember you mentioned to me earlier that the 3411S already has 3x the torque of the stock PRS Alpha setup now that I mention it.
We are talking about a bolt together frame design that has both deficiencies and of course limits. Excessive torque in the X (normal Y, but SB X) direction will have a tendency to rock an overly top heavy gantry design placing undue stress on the gearbox shaft. Which is the only physical component holding the gantry on the rails. Excessive torque in the Y (normal X, but SB Y) will cause the v-rollers to climb the V, load the gearbox shaft and cause an off line cut by 10 or 20 thou. There are no machined surfaces to ensure that line of travel is straight and true.
I have had the 3411S models run 1400 ipm, but usually limit them to 1000 or under. How fast do you need to go, and how quick do you need to get there? Those things are scary when you know that not much more than gravity is holding them on the rails.
And make sure that you use pinions with keys in them or you will spin them on the shaft.
Gary Campbell wrote: ↑Thu May 28, 2020 3:21 pm
We are talking about a bolt together frame design that has both deficiencies and of course limits. Excessive torque in the X (normal Y, but SB X) direction will have a tendency to rock an overly top heavy gantry design placing undue stress on the gearbox shaft. Which is the only physical component holding the gantry on the rails. Excessive torque in the Y (normal X, but SB Y) will cause the v-rollers to climb the V, load the gearbox shaft and cause an off line cut by 10 or 20 thou. There are no machined surfaces to ensure that line of travel is straight and true.
I have had the 3411S models run 1400 ipm, but usually limit them to 1000 or under. How fast do you need to go, and how quick do you need to get there? Those things are scary when you know that not much more than gravity is holding them on the rails.
And make sure that you use pinions with keys in them or you will spin them on the shaft.
I supposed I won't need to be running any faster than the 1000 per minute that you've found to be safe and effective - But well understood, thanks for the further clarification Gary.
Richards wrote: ↑Thu May 28, 2020 1:22 pm
Gary,
That is correct; however the hub can be connected to two Ipc-5 power supplies and four motors (more if multiple hubs are used). I've made custom cables and I've used stock cables. Crimpers to make good cables are pricey if they are efficient. Of course on a router custom length cables might be needed.
Mike are the power needs of running 3411S motors on a 4x8 such that you need two IPC-5 units? I believe Tom @Tlempicke used 2 on his 48" SB Buddy conversion.