- February 10, 2017 at 2:11 pm #27164
I don’t know if this has been asked before, but would it be worthwhile to upgrade the stepper motors in the MPCNC from the 76oz/in ones in the kit to 92oz/in, which are the highest NEMA 17 torque I can find?
What advantage would I gain? Right now I can easily cause the steppers to slip with a good yank on the gantry, but I haven’t seen it slip while cutting so far.
Just wondering if anyone has any ideas…February 10, 2017 at 5:39 pm #27179
Don’t see a reason to do this. The current steppers can bend the tubes on some of our larger builds.February 10, 2017 at 8:26 pm #27183
Dui, ni shuo de duiParticipant
That’s the ones I use. They work great. The more torque the better, but as Barry just said, it is useless if you don’t have a very stiff structure, so either reinforced tubes or small CNC size.
In my opinion, the biggest advantage to have torquey motors here is that it will give you a bit more freedom of mind, since you will better trust your CNC to work fine even if you are not constantly around. Wood is an inconsistent material, you have some soft and some hard spots even in the same plank, so the amount of torque needed is not constant and not previsible at any point. Having more torque means that you are a bit safer regarding the risk of missing steps on some hard spots.
Don’t forget to take into account that these motors will be heavier and longer than the other ones.February 11, 2017 at 5:09 am #27186
Meh, I’m not even maxing the current I could be using with the steppers I have. If I needed more torque, I would start with that. But on my 3’x4′ build, the steppers aren’t the limiting factor.February 11, 2017 at 8:34 am #27203
How are your steppers currently wired?February 11, 2017 at 10:25 am #27227
My steppers are currently wired directly to one driver each. No parallel or series, I’m using all 6 slots on the Ramps board with Estlcam set up to use all 6.
I find it hard to believe that these steppers can bend the tubes, especially when I can cause then to slip with a good yank. That’s mostly what I’m worried about as well, because I was recently cutting bamboo and my workpiece slipped and even though the dewalt stalled, before it did that, the stepper slipped and lost a whole lot of steps.
16oz/in of extra holding torque might make it more rigid, but that’s why I’m asking, because I’m not sure.
In my 2.5′ x 2.5′ machine, the place it flexes the most is where the belts attach to the zip ties, but apart from that it’s been great. I’m just trying to find ways to improve this machine, haha.February 11, 2017 at 10:38 am #27233
So let me back this up a little bit.
You can’t just brute force drag a sharp object through wood and expect good results.
A proper cut should have very little force exerted on the machine at all. Proper feeds speeds should cut like a hot knife through butter. I would work on your setting before you do anything else.
Try using a full sized router by hand on wood and mess with your amount of force, if you push hard enough to stall it all sorts of things are wrong about that. There is a proper amount of force for every material, and for wood it is very very little.
Everyone is so quick to jump at a bigger router and bigger steppers and more voltage. CAM is a science and it is peoples full time very well paying jobs. There are a million things to learn.
If you drive a Lamborghini to the grocery store doesn’t mean you will get there any faster than a driving a Volkswagen bug, you can only drive as fast as the conditions permit.February 11, 2017 at 3:22 pm #27260
Fair enough, I’m aware that there are better ways to approach things, all I’m asking is if there will be an improvement to using more powerful steppers, and if there are improvements, where would they be?
I’m cutting bamboo, and it’s nothing like what I’ve worked with in the past. To be honest it’s more like aluminum more than it is like wood, as strange as that sounds. I’m just trying to find ways to improve my MPCNC, and I just happened to come across these steppers and I was wondering if they would make a difference.February 11, 2017 at 6:34 pm #27271
I would spend the time testing gcode and different cam techniques, rather than spending the money, but that’s me. I built a budget cnc…
I have a few videos milling IPE, that is some of the worlds most dense wood, bamboo should be easier (I assume). Have a look at my videos and my settings to get you going down that path.February 11, 2017 at 9:12 pm #27300
I would imagine bamboo is so fibrous that it’d be really easy to get the bit to tear instead of cut. Proper speed and RPMs should allow a bit to deal with it as well as normal wood. Maybe too many flutes or too fast? You want the cutting surface to have time to get a bite.February 11, 2017 at 10:56 pm #27307
If you are skipping steps, and you don’t think you should be then increasing the driver output should also help, but you run into heat issues. I don’t have mine set at near the theoretical max, and I feel that they are strong enough already.
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