Nema 23 or 34 Clearpath Motors
I have a 4'x4' Fineline machine with nema 23 motors.I have been working through issues with the motors losing steps and stalling even when slowing the machine way down. I guess what I bought was just too weak to handle the weight of the machine. I have sort of decided to go with a set of clearpath motors so I can max out the machine and not have to worry about the machine skipping steps on me anymore.
I was thinking of upgrading my nema 23 setup to a nema 34 setup for the stronger belts (I imagine this would help reduce backlash at higher cutting rates/acceleration), but I have not heard back from Nate to upgrade my system to a nema 34 R&P. I was hoping to run a SDSK-3421S-ELN based on other users experiences, but am not sure how to upgrade my R&P. There is another option to keep the nema 23 1/4" shaft that I have with the SDSK-2331S-ELN. It is about $600 cheaper than the 3421S setup since I wouldn't need to change out the R&P and coupler on the Z axis. The only downside is the reduced amount of torque across the range. From 250IPM on, it is about on par with the Nema 34 kits offered by CNCrouterparts and Nate.
I guess I have two questions trying to make up my mind on which to get.
1. Since I haven't heard back from Nate, is the CNCrouterparts rack and pinion compatible with the FLA machine to go with the nema 34 setup.
2. Does anyone have any experience running these 2331S motors with a 1/4" shaft. Last thing I want is to spend a good chunk of change on a new setup and run into similar issues due to a weak link with the belts slipping or stretching with higher powered motors.
Thanks!
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Re: Nema 23 or 34 Clearpath Motors
If you do not hear anything back from Nate I would contact CNCRouter Parts directly. You more than likely going to need to upgrade your power supply and perhaps driver modules, and you can purchase those pulleys for the motors in a larger bore size to fit the 1/2 inch (mine are that size) shaft of the NEMA 34 motors.
1000x750 Workbee CNC - Mach4 - PMDX USB - Windows 10 Pro
Re: Nema 23 or 34 Clearpath Motors
Hi drxlcarfreak, I just wanted to clarify that NEMA 23 ClearPath motors have a 3/8 inch shaft diameter. Optionally, on the 1 stack and 2 stack ClearPath motors (i.e., CPM-xxxx-231… and CPM-xxxx-232… part numbers), you can also get a 1/4 inch shaft diameter.
The 3 and 4 stack NEMA 23 motors do not have a 1/4 inch shaft diameter option because of their higher power. So if you end up going with the 3 stack CPM-SDSK-2331S-ELN motor you mentioned, you will need a 3/8 inch bore on any couplings or pinions.
Please feel free to contact us at https://www.teknic.com/contact/ if you have any questions about the ClearPath system, options or accessories.
Best regards,
Warren
Re: Nema 23 or 34 Clearpath Motors
Yeah, I did contact them. Unfortunately, they can't guarantee that it will be a direct fit. Looking at the pictures though, I can't imagine that they are different enough to not work. Yep, unfortunately, I will need to replace the power supply I have with a larger one. The beauty of the Clearpaths though, is the driver is already integrated into the motor. Just need the power supply and step/direction wires. Downside is I have to rewire the machine too, lol. I was originally planning to just get the pulleys and belt, but looking at my R&P plate, it must be an old one that only allows nema 23 motors, which is weird since I only purchased it 9 months ago. It isn't the black one on the site that has all of the refinements done to it that I saw in another thread and assumed I was getting. I only noticed it a month ago, when I was trying to figure out how to upgrade. When I was building it, I was just so excited to have a machine. Kind of really bummed about that.If you do not hear anything back from Nate I would contact CNCRouter Parts directly. You more than likely going to need to upgrade your power supply and perhaps driver modules, and you can purchase those pulleys for the motors in a larger bore size to fit the 1/2 inch (mine are that size) shaft of the NEMA 34 motors.
Doh! I knew that! Completely slipped my mind when comparing the specs to the packaged stepper replacement. Thanks Warren, I will contact you there. Hopefully I can get a size recommendation!Originally Posted by Teknic_Servo
Re: Nema 23 or 34 Clearpath Motors
I have the CPM-SDSK-3421S-ELN motors (enhanced resolution) on the rack and pinion drives and the CPM-SDSK-3421S-RLN (regular resolution) on the Z-axis (ball screw) on a 4x2 Saturn machine. The closest NEMA 23 is the CPM-SDSK-2341S-ELS. The continuous torque is only about 60% of what the 3421S will do, and it has a higher max speed. The continuous power ratings are pretty close (227W for the 3421S and 201W for the 2341S) but that isn't the whole story. Power is (Speed x Torque). The 2341S gives up torque in favor of more speed.
Unfortunately, you don't really need more speed out of the motor. The NEMA 34 motors will drive at about 1100 RPM at its rated continuous power. On the Saturn, there is a 3.2:1 reduction after the motor driving a pinion (gear) that has close (not exactly) to a 1" diameter. For every gear rotation, the axis moves just a little less than 3.2 inches. With the 3.2 reduction, that means the axis moves about 1" per motor rotation. So max speed would be 1100IPM on the axis. That's pretty fast already.
With the NEMA 23, you get about 1650 RPM at Continuous rated power. You lose a little speed because the belt drive ratio for the Saturn is only 3:1, but you still end up with a max speed of close to 1550 IPM...while sacrificing about 40% of the continuous torque. By slowing the motor down, you can use a little more of the "max" torque spec, but to maximize the life of the motor, you are better off doing that less frequently. What are your current motors rated for? Remember that steppers are usually rated for max torque which only applies at pretty slow speeds. You need to look at the motor curves to really understand what they can do. The NEMA 23 ClearPaths will probably outperform what you have, but I'm not sure by how much.
Sorry for the dynamics lesson...this is a long-winded way of saying that the NEMA 34 ClearPath is probably the better choice. The NEMA 23 ClearPath may be more capable than your current motors, but for that investment, I think you would be better off making sure that you really solve the problem. I am a big fan of the ClearPath motors, but you may also want to look at the NEMA 34 motors that Nate and CNCRP sell. You can probably save most of the money you will spend on upgrading to the larger Fineline drives, and lots of people are running similar motors successfully on the Saturn machines. You may have to upgrade your stepper drive electronics and power supply, but you will provably save on wiring.
-Robert
Re: Nema 23 or 34 Clearpath Motors
I love reading this stuff! With the amount I am planning to spend I have made torque graphs and calculated what each option will cost me as well. So it's good to hear someone else recommending the more expensive version that I am trying to talk myself into.
Right now the costs to upgrade for each is, assuming the wiring and enhanced version of each:
2321: $1,783
CNC RP Nema 34 - $1,807
2331: $1,918
2341: $2,102
3421: $2,533
The cheapest only being a very slight upgrade from what I currently have, so for the price, definitely not an option. All the rest require either new 3/8" couplers, or a NEMA 34 R&P, hence the price jump. Torque wise the CNCRP fits between the 2331 and 2341 motors, so in my mind like you said that leaves either the CNCRP steppers, 2341 and 3421. The 3421 setup, does have the hidden added benefit of giving me enough spare parts to build a spare machine minus the frame and rack. Ahh, decisions, decisions...
Re: Nema 23 or 34 Clearpath Motors
Keep in mind that motor specs are a little ambiguous unless you have a nice torque-speed graph with maximum and continuous lines on them. The maximum torque on a motor rarely happens at maximum speed. Torque is also generally proportional to motor current. Motors current is what generates heat in motors and is usually a big limiting factor in a motor design. You can't keep running a motor at its maximum torque for a long time, because it will overheat and burn up. Designing for the continuous torque and power ratings are a much safer bet. Unfortunately, not every supply provides that data, so it makes comparing the motors more difficult. You can design the system to exceed the continuous torque/power ratings, just make sure that you don't plan to use that much torque/power all the time...unless you like replacing motors.
The motor curve fore ht CNCRP motor is a max torque curve. Your rankings of the motors looks pretty correct based on max torque/power. The big jump happens when you get to the 3421S. They don't call them "stepper killers" for nothing. The performance is much better for a comparable size...but you do pay for it in $.
-Robert
Re: Nema 23 or 34 Clearpath Motors
That's fair, especially the case with my current motors. I was a rookie when buying it and confused PPS with RPM, and the graph stops at 390 RPM, so my guess is it drops off pretty quickly after that, and like you said they are most likely peak numbers. Being chinese steppers, most like slightly exaggerated peak numbers. I am comparing what I think is maximum torque for each.With most of the cutting I do, I do not think that I would be cutting in the peak torque range anyways. I really want to increase my cuts a little, but more importantly to me, is speed up the rapids between cuts and be able to increase the acceleration so that the machine can maintain more of a constant velocity through the material when changing directions.
You are telling me, I threw them all in a graph together up to 1500IPM just to see how the max torque curves compared. As you can see below, the 23 SDSKs are on par with the CNCRP motor, but the 3421 blows the torque out of the water until 500 IPM. I am leaning heavily towards these, if not for surety that I wont ever need to upgrade, and I will have an excuse to use these spare parts to build a machine that requires less torquey motors down the road.
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