I just bought a Ramps board in order to use the dual endstop firmware, but then I discovered that unlike the Arduino, the Ramps only takes 12V. I am planning to use medium length Nema 23 motors with a DRV8825 driver for each. At 12 V are these going to be effective? I want to cut aluminium with a flute and leather with drag knife. I hope that’s not too ambitious.
I also have a Ramps board and the input voltage is stated as 12-24v, are you certain yours is 12v only. What are the specs of your stepper in terms of Amperes? As this will have an impact on power requirements. I understand the holding torque is more important with steppers…
I’m sure someone more knowledgable than myself will be along shortly…
Actually I’m not sure; I was told by someone on the Facebook page that it could only handle 12V. It looks like you are correct though, by accounts that I can find elsewhere on the web it seems like it was designed for operating at 24V which should be fine.
The motor amperage I cannot remember, LOL. However, I will be going by temperature: running them pretty warm -but not hot to touch. I am guessing that will be somewhere between 0.5 and 2.5 Amps. As I understand, this is a value averaged over time; the current is not actually DC, but some sort of square wave with duty cycle. This is great because it means almost zero heat disappated by the driver boards (hence the tiny MOSFETs you see these days that still run so cool even while delivering several amps) and you can set the average power by changing the duration of on time (done on the stepper drivers themselves with the little potentiometer).
I was worried I was limited to 12V because I imagine the coils in the motor have significant inductance and probably need more voltage to get them passing current quickly enough to operate responsively. If the board delivers 24V and I have two beefy motors on each axis, each driven individually, I think it is going to be pretty dam good!
According to this page the Ramps 1.4 boards only supply 24V to heated beds - but only 12V to steppers. So there seems to be a lot of conflicting info. The capacitors on the board that I can see have 35V on them, but this isn’t much comfort really.
According to this page on reprap.org, the Ramps 1.4 boards supply 24V to heated beds - but only 12V to steppers. So there seems to be a lot of conflicting info. The capacitors on the board that I can see have 35V on them, but this isn’t much comfort really.
How do you plan on making a 23 fit? 17’s really do have more than enough power.
Why 24V, it is only slightly more efficient? The ramps can handle it but you need to cut the diode and supply the mega with it’s own power. This used to be easy to find info, I am guessing it fell out of fashion if you can’t find it.
Kinda the bottom line is why go through all of this? The steppers never have been even close to the weakest link. The first videos I put up were salvaged/old 42 oz/in steppers carving aluminum. I now supply the kits with 76/oz in and under power the heck out of them so people don’t rip there machines apart. There was a video early on of a 24 trying to go to far and crushing the CNC. I have most of this in the FAQ’s
Ha! Well to be honest I started off with plans to build a Root 3 CNC… then a friend who found the design a little problematic told me about your design. I have 4 Nema 23s. Also, my router is a bit heavier than a Dewalt, so I figured it might be ok to use them. Sure enough, someone’s already created MPCNC motor mounts for Nema 23s on Thingiverse.
I don’t think there are anymore, maybe though, there were for the old design. I would say sell them and take the extra money. They will not add anything but extra weight. The recent steel milling vid, he was using tiny 17’s smaller than the ones I sell. 24v is a hassle, a large router is just heavy. Making a bunch of mods to end up with an expensive sub par build…? It is all about balance. Using a chainsaw to cut a birthday cake when a butter knife does the job better?
It’s not because I wanted to change your design, i’m just using what I have. Ordering 5 small steppers would have been a lot cheaper too. If the mounts are not available anymore I will try designing my own.
Lol -the man in the video is very lucky he didn’t fling a spoon into his front teeth or receive Go-pro shrapnel in his eyeball…
24v is better for achieve greater accelerations and speed. usually it’s good for a 3d printer. but if you don’t need this in cnc - 12v seems ok.
if you decide to use 24v you have to modify your ramps because 5V dc-dc converter on the mega is too weak. remove diode D1 and make separate power to mega with cheap dc-dc plate. tuning it to 24 -> 9V usually assumed as best way. https://reprap.org/wiki/RAMPS_1.4
i am/was planning on using 24 volts as well to my stepper drivers as i plan on using nema 23’s. with the help of my electrial engineer brother, we found that feeding a 24v line directly to the stepper driver would work. that is, cutting the pin that goes down into the ramps board and wiring in a 24v feed from the top. im using 1" cold rolled steel as my tubing so I have a little more mass to move around. i am planning on using 270/oz/in motors