I’m hoping to get some help from some of the members of our community who are better at the electronics side of things than I. I am in the process of getting ready to make a new motor shield, but am unsure what specific pairing of motor drivers and Arduino to make.
I have a Voltera PCB printer from work that I need to practice with it. My company just started selling them and my boss wants me to be competent enough to train our customers on how to use them. It’s a really neat machine, it can both all the traces as well as solder paste. It also has the ability to flow that solder for surface mount components.
As for the Maslow electronics, I have been very interested in doing an Arduino Due build. The motor shield for the Due is designed around the standard L298P motor drivers that the Mega shield uses. I do see some documentation about how to make a TLE5206 shield to work with the Due, but it seems unclear to me.
This image from the Due instruction page shows a jump needs to be made and some traces need to be cut on the SMD TLE5206 board:
I think I can figure out how to edit the trace map to make that work. What is not clear on if there needs to be the additional resistors, filter caps, and eeprom storage that is on the L298P board. If so, then does the board need to be further modified to incorporate these components?
Further information on this has been documented here
Is it worth sorting out the TLE5206 type of board or are the gains going to be too small? Would it make more sense to just run a Mega-powered TLE5206 over a Due-powered L298P? I know some people have blown up the lower powered chips, but I haven’t had too many problems from them on my machine. With some of my future plans for my machine, I will be pushing the motors a lot more, so maybe I will need the additional headroom?
I have found the L298P to be perfectly okay for this application. There have been folks having some heating issues, but I believe that it was due to the weight of their sled vs the weight of the counterbalance. The bungie-cord method does not supply a constant counter-weight to the sled, and therefore the motor currents get quite high. I use water jugs and a couple pulleys to provide about 16 total pounds of counter weight against the 22-pound sled. My motors and drivers barely get warm.
In the source code on the github site you list, there are compile time switches (#define) for the various versions of shield boards (both TLE and L298 based). The Due software requires the EEPROM to store the GRBL parameters and run-time position stuff, and that is why on the schematic above it was added to the Due (I did this using a Mega-breadboard between the Due and the shield.) I did modify the shield (latest at that time) artwork to support the EEPROM and that is what is on the site.
Hope this helps.
What you’ve said about the weight makes a lot of sense. I didn’t like the bungees myself so I have counterweight system in place on my machine. They’re very light, only a few pounds each. Its really just enough to tension the slack side of the chain. My sled is right around 26 lbs, so that’s only slightly heavier than your machine.
I think I will try to blaze ahead with the L298P’s for now. From what you’re saying, they will probably work just fine for my application. It’s great that you were able to locate all the additional components on the same board.
If I do decide to go down the TLE route, you’re saying that you made an in-between board which has all the resistors and EEPROM? It probably wouldn’t be too hard for me to print one of those, either.
Thanks for the support, this has been massively helpful!
when the chains are long, the tension on the chains can get very low (under 4
pounds) and with a 2:1 mechanical advantage due to the pully, if your weights
are > ~8 pounds, then at some point the tension on the slack side of the chains
becomes larger than the tension on the sled side, and the motor will turn a
little bit without moving the chain (as the gears move from the pressure being
on one side of the gears to being on the other side), so there will be a curve
across your workpiece where things don’t quite move as expected.
Given that we are talking about woodworking here, not metal, this may not be
noticable, but you should be aware that it’s there.