Duet3 Mini 5+ - 2x TMC5161 expander board
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Aiite, hear me out -
So: Triple Z is the new hotness - Like the excellent Jubilee&Railcore, or my hopefully-pretty-good stablebot, and a few other machine platforms like the voron or similar use plenty of drivers (6-7 drivers) One common thing is that they tend to use nice and big X and Y motors (Jubilee&Stablebot use LDO's 60mm 2A RMS Nema 17, for instance) These pair nicely with the hefty 5160 drivers on the 6HC, but when we drive other motors like the Z axis or extruders, 5160's capabilities are pretty underused and leave alot of cost underutilized. The opposite goes for the D3 mini - the TMC2209s' work great for Z, Extruders, and they're plenty fine for driving motors at moderate currents, but If i'm buying a big old motor, I'd like to be able to chuck the full power at it. Something else that comes to mind is maximum voltage - Everything is more/less 5,12, or 24v locked, and even tho the D3 6HC is rated for more, it leaves the fan/heater/whatever options with pretty clunky/custom options.
Here's my improvement/solution/request:
Make an expansion board for the D3 Mini with 2x TMC5161's.
They're drivable via UART, can chuck plenty of current for even the largest NEMA17's, and use the same codebase to chat as the 5160 (I think). The expansion could use a seperate ground and VMOT from the D3 mini, for a higher voltage PSU (or just activate jumpers to use VMOT from the mini).
It seems like a great "right size" option for these higher-end machines - completely user-selectable (don't want it? don't buy the expansion!) but is plenty capable for what users like me are looking for - 2 high-current drivers for XY, and even allows for "easy" scaling to high-voltage motor driving for even faster maximum speeds. Could be a pretty killer feature that drives sales as well
Thanks for listening.
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Yeah; I've dwelled on this, and I'm definitely in favor of this idea.
A Duet 3 Mini + ($~50) 2x Expander board for XY steppers would be much cheaper than a Duet3 and give you one extra port to install your first extruder tool. At that point, both setups can add subsequent tools with either a 3HC or 1HC.
I think one of the hesitations for folks to jump into the project has actually been the sticker shock of the electronics. I'm all in favor for something well-engineered that's been tested, but I also think that a convenience like this expander board could ease that jump. Rather than start with a Duet 3 and 3HC, they can add the 3HC later when they have a single tool running and can budget more for the project a few months later.
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@poofjunior I've ordered parts to prototype such a board. I don't know yet if it can be built at the same size as the 2209 board more or less as it would be nice if it could dissipate more current.
I'm targeting 48V.
No idea of cost yet.
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@veng1
would be interesting to know, how good the firmware handles different (quasi onboard) drivers? Especially for input shaping.
The external toolboards have the advantage of their own CPU and FW to handle their drivers.
