I have some large slabs and keep thinking i ought to mount a LR3 right on my sawmill to surface them.
Seems like a full size router will do better. I know its heavier, but surfacing doesn’t realy require precise, complex movement.
Has anyone experimented with this?
I’m sure you could but seems like a manual sled setup would be more appropriate since you don’t need a high degree of precision. As another option, someone I know is building a timber frame house and he has one of those portable electric planers rigged up to a manual sled setup right after the saw. Works surprisingly well and gives a finer finish. But that’s on cants, not sure what kind of tear out you’d get on a slab.
I did not experiment with this, but maybe it’s yet another time where I show off one of my crazy ideas 
Adding a second LR3 on the same Y track with a simpler/stiffer construction like this could be the ticket…
You could even go with a cheaper controller board, as there would be only 3 motors to drive…
First you use the “surfacing LR3” with the full-size router on it to flatten the slab both sides, then, with the slab already in place you can machine it with the “normal” LR3
Interesting. That’s a whole different approach to an IDEX or multi-tool setup…
Full size as in something like Bosch 1617EVS 2.25HP ? Think @Autonomous has this setup on his beefy LR3, he shared a mount for that router too.
I don’t really think this would work as an IDEX, mainly because you’d have to get both endstops and squaring perfect to have good positioning between the tools
On an IDEX build you only have to adjust the X limit switch for the second carriage, which is easier
If you have two completely different tools (like a laser or this flattening jig), or if you have a very long table and want to machine two parts at the same time, this could be useful.
Also, it’s way cheaper to make a dual-x-carriage idex (only one board, and you just have to re-print a core)
Yes, at this point it isn’t really IDEX at the controller level, it would be job-level where you’re essentially running two different routers with unique work offsets to finish one job.
But, it would be relatively inexpensive to build- if you could solve the software/work space issue.
Good point. I hadn’t thought of that. Maybe even a positioning jig- first operation happens on one part of the system with one X gantry, , then the next operation happens further on where the next X gantry can work on it.
Probably not worth it- but an interesting thought exercise.
More complicated in software, though.
A multi-head milling system is also much easier if you go to smaller spindle packages than a trim router.
I think it is a trade off. You can move a smaller router with a smaller bit faster than a large router with a large bit. Do you really want to modify everything just a save a maybe 5-15 minutes or robot work time? The smaller bit is easy to tram as well so the parts should come off more accurate for the same cut time.
Another option. I built a “manual” version of a mpcnc/LR. Conduit rails, 3-D printed bearing housings, plywood mount for router. Works really well. Big ol flattening bit. With the big router, I can take 1/4" deep passes at about an inch wide. Makes quick work. Mine is optimized for quick setup. Have made many modifications since revision one.
That’s more like what I had in mind
Just suggesting that if you already have an LR3 and will build a slab flattening jig like this one, you can do so on the same table and Y rail as the LR3
And even maybe reuse a slightly modified version of the LR3 xy plates, an LR2-style x carriage, slap 3 motors in there (or not) and have it all automated
To me, it makes a lot of sense in space optimization, re-use of existing parts design, and cost reduction
Having the motors to automate it is totally optional and could be added at a later point
Just to be clear, this makes absolutely no sense if you have a single flattening job to do… then just use the LR3, it’s very capable
But if you do this regularly this Can bé a nice tool addition to the shop, complimentary to the LR3
Neat! Are you using 1" EMT? Looks like you’re able to change distance between the rails to keep distance not much wider than the slab, to help rigidity?
Yes, I believe its 1" EMT. The shorter rails are simply a 10 foot stick cut in half. That table it is sitting on is wide enough to do about a 30" wide slab or so. If it gets any wider, I move the assembly to the concrete floor and extend the rails.
