My plan is to get 6", but I’m wanting to use it to surface larger cutting boards. I’m wanting to do boards that are 2" thick, so I need to be able to clear the top of that.
I’m also trying to build one machine that can do everything I need, hence the 4’x4’ cut size.
I can always stack mdf boards if I need to increase rigidity for something
My LR Z is not cut down. The only time I go very high is when I need to get to the screws under the plate.
I still think of the LR as a sheet machine. So 4" seems good to me. If there is any rigidity advantage, I would rather on the small side. The laser is cutting at a bit higher, because I have a different spoil board. But still under 4".
But I know there are people who are going to want to go bigger, no matter what.
I am not quite to that part yet but if linear bearings are involved a size will need to be picked for the kits…Either way I do not see any reason it would not be open-ended like it currently is.
I guess to be more honest I had an idea that would limit the Z…but I think I can make that open-ended to some degree as well, with a couple more screws.
If there were a way to mount the router higher, perhaps that could offset some of the issue of long tools? It could be bolted down, and maybe not incur as much of a penalty as a longer active moving Z range?
The 611 and 770 can be slid up and down in the mount pretty easy, but I try to build them with the collet just a few mm above the minimum profile of the machine and the machine 1/2-3/4" above the deck to account for normal endmills.
Oh I just realized that the machine has to clear the workpiece too, not just the collet. If you have a 4" workpiece and a 4.5" long bit, the machine has to raise to 8" to be able to lower by 4" and still clear the workpiece. I was thinking you could just raise the router and have only 4" of working space, but that was wrong.
A hole in the table would work though, and accommodate much taller workpieces too like box joints. A job that’s 12" by 6" with big Z is plausible, but I can’t imagine 48" by 96" seeing more than a couple inches. So a hole should be fine for the tall cases. In the extreme case, a long narrow hole, and your 4th axis can turn table legs even if you have only 3-4" of Z.
My plan is to build a water table / CNC table so I will have some sort of drop table, probably not a box joint rig, but it will kinda show people how to adjust the table not the machine to use 12" Z for surfacing something giant like a raw slab.
I met a guy that pays a ton of money to have his slabs surfaced on a CNC…I think two slabs cost would have easily paid for a LR…not to mention all the times he has paid to have designed machined in as well. Plus he has to transport the piece back and forth days apart. So, a new market that could easily benefit from something like this.
Even surfacing a large slab, you don’t need a lot sticking out, so in that case you can raise up the router so it just peeks out below the gantry. If the slab is 4" thick at the thickest part and the machine can lift to 4.5", you can use 0.5" sticking out and mill the whole thing down from 4" to 2" if you wanted to. You might have to empty your vacuum twice along the way…
Same with surfacing cutting boards, (or shallow v-carving), your working Z doesn’t need to be twice the workpiece, it just needs to be workpiece + depth of cut. For through holes, then yes it has to be twice workpiece.
But yes a drop table should be a pretty “standard” feature for pieces smaller than 48".
Maybe someone will do something totally stupid and awesome like mounting a $100 harbor freight bandsaw.
MPCNCSM
Mostly Printed CNC Saw Mill.
I have been kinda banging my head trying to solve a tiny printabuility issue, finally got it (mostly me and a fusion360 issue really). The sample that is printing is working…not everyone will like it but be able to print holes horizontally no room for teardrops but it is printing great with thick layers so thinner ones should be even better… That means I can tweak the rest of the holes and move on to the ZY part. The Tool mount, X axis, seem 90% complete (fillets, wire/vac management, and logos left 
) . That sets a lot of the variables, so hope to get on the ZY part later today or tomorrow.
Or Logrider2.
Ummmmm Nope!
I was wrong…but I did it a different way. Tester printing tonight. Basically the Core of the new build. Not close enough to share much else than small victories. Still no logo’s…
I am playing with some liner rails, and dam if they are not shockingly expensive. I think they are actually required in this situation but I am not happy about it. 4x200mm with two blocks each…hmmm. I will continue down this road for now but I really want to not use them just because of the price. I so desperately wanted to decrease the build price.
So far it does balance out, they are the same-ish as DOM or Stainless rails for the X…but I hope those are no longer needed. (So far if you have them you will be able to reuse them).
I was wondering whether the sbr25 bearing blocks could match with 25mm stainless tube - even considered buying a block and test it myself. The weight saving with tubes over solid rod + the aluminum base would be huge. And the tubes have been proven to be stiff enough anyways…
edit. I know it’s wishful thinking, but if anyone would have loose parts, I’d like to know if it’s even close.
I am pretty convinced they are the weakest link of the LR2, the new build is completely based on a different style of the X rails.
Alright, mine is only 600mm working span on X-axis so no problems with stiffness.
But whatever improvements/changes/upgrades I’ve thought about, it always starts with making it bigger. And unfortunately it hasn’t really progressed from there.
I think I need to wait a bit and see what you’re coming up with. None of the stuff I’ve started to sketch out could be considered an improvement in any way over the LR2.
Well, Fingers crossed this keeps progressing, and I really need to get some sort of build complete to do a full test. BUT…so far I am stoked and there are no compromises except the cost of the linear rails. For me I might be able to buy them in bulk and get a decent price, but buying them outside of a kit is a bit of a bummer.
so the lr is going to use linear rails? those must be massive