DIY V-Slot Gear Rack

I have read for years that for extremely large format machines, at some point gear racks made more sense vs belt or lead screw designs. The problem always was, in my mind, the cost of the gear rack.
This is quite impressive…


I’d have to dig up the post, but someone on here created a gear rack setup for their MPCNC. I’ve since lost track of that project, though.


I believe dj4linux had printed some, but they were much shorter. I thought I talked to him about them, he sent me the files, but like most things, I never got around to printing them…
These looked interesting not only for their length, but also the fact that they just slide into the v-slot.
I have no idea how much slop there is in these, but I can just imagine bolting some v-slot to the side of a table (below the surface of the table), sliding these in and going to town - might make a multi-use table easier to work with.
How would you get a LR to roll on the track?
How would you keep sawdust / aluminum / whatever out of the rack?
Yea, dunno…
How durable would the plastic track be with the weight of the bridge & router on it? - I suppose if it was cheap enough, like belts are, who cares…

Pro machines either run the gears inside an enclosed area with a dust belt going around the track area like a conveyor belt, or run the track upside down under the table.

I’ve mostly see this.

How do you reduce the backlash on a gear like that?

Mesh them tighter, after that you only get software/firmware compensation. Easy on big machine… lots of small moves not so much.

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The machines I delt with were angled gears so they had less backlash to start with.


I mean, marlin has backlash compensation built in now, this is a pretty valid solution these days. Some herringbone gears and go for it.

I wonder if we will ever switch from belts.

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I was speculating on this topic about a month ago. I came to the conclusion that rack and pinion like this could work and be easier to implement for large high speed low torque machines. But I worry that CNC cutters would need to be geared down (or upgrade to NEMA 23) and that just gets a little more difficult to implement.

Just my opinion. But I’ll stick to belts on all my hobby machines.