New LR2 build

Hey Folks - I’m getting ready to embark on my first build. I think I’ve decided to go with a LowRider at this point, I’ll lay out the criteria and see if any of you have further input.

Build goals:
-4’ x 6’ work envelope.
-interchangeable tool heads: laser engraver, small spindle to cut ¼” lexan and shape foam, plasma cutter (I’ll start with the easy ones and sort the plasma out after it’s functional, since I know that can be a pain).
-positional accuracy is more important than rigidity since I don’t intend to make heavy cuts
-built on a frame constructed from 2”x2” steel tubing, slats for plasma cutting and removable spoil board for the rest

One question - what kind of positional tolerances can be expected from a low rider? Not errors related to cam/cutting but repeatability of the unloaded machine. I’ve seen some people say ~.1mm, which is pretty good for a machine built like this.

I have a spare duet controller (older 0.8.5) I may use for starters, I can print my own parts and probably buy the hardware kit from the store. I haven’t found much information on running a plasma table with a duet controller, is there any reason to start with a different controller from the get go? I have an SKR mini in one of my printers, so my second choice will probably be the SKR pro.

I still have to square my LR, but I recently milled 14 similar parts in 1 run out of a half board 18mm multiplex and it was close to 0,5mm of tolerance. It was perfect as I can keep in mind this tolerance while making a design!

You can always upgrade afterwards

I’m running my Primo on a Duet 2 wifi, and will probably have my LowRider converted to use the same (Currently on an SKR Pro) very soon, because I really like the Duet Web Control interface. I think there are a couple of us that can help with a RepRapFirmware config.h file for you.


Tolerances on the LR are tricky. It can be tuned but it tends not to stay that way.

I can get my lowrider to be accurate within .025mm in XY over 100mm for a cutting session using sensorless endstops. I can stop power down rehome and still be accurate. HOWEVER if I come back 3 days later it loses its calibration and is more like .2mm without recalibration. Z is far less accurate initially due to gantry sag call it .5mm across a 4foot span.

For my purposes this is very acceptable… to a machinist probably not. YMMV.

Thanks all!
I’ll be looking around for more info on the Duet firmware, if I have troubles I’ll ask.

.5mm sag on a 4ft span is doable. I’d like to get it a bit less, but we’ll see.
I’m hoping by eliminating some of the wood bits the temperature/humidity changes will be minimized, but the 60" long DOM just doesn’t feel very stiff. I’ll try to minimize the weight of the tooling. I’ve got aluminum to cut the plates from and the 1" x .065 DOM, just need to start printing parts then order the kit.

One of the main uses at this point will be cutting lexan/polycarbonate windows for cars, so I won’t need a heavy spindle for that.

Can’t wait to get started!

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