LR4 working dimension question

[bernoodoo (Chris R)]

Hi everyone,

I’m in the process of printing/building my LR4 (first time builder) and I was having a question about the working area for a full size build.

I want to be able to cut full size MDF sheets (49x97) and be able to program the tool plunge outside the sheet if need be.

Do I need add length to the axis (maybe 50x98?) or i just use 49x97 in the calculator ?

Thanks everyone !

[franklyrosalind (Zach Zundel)]

Do you mean you want to be able to cut outside the sheet size? If so, yes, you need to include the full dimensions where you want the tool to move as the cut dimensions.

You’re talking about a quite-big machine, though. It may be worth brainstorming a bit on your table design to see if you can’t figure out a way to rig the plunge cuts inside the table so you don’t need the extra Y. Up to you though.

[DougJoseph (Doug Joseph (design8studio))]

One thing to bear in mind is that the center workable part of the table need not be as wide or as long as one’s outer “pontoons” on which the LowRider rides, if your table is designed like this one:

~ $200 Full sized Lowrider table, Non-CNC Build

[PXL_20250205_233205080] I went out to see exactly how I would make a table for a 4’x8’ Capable CNC if I did not already have a CNC. Besides just two full sheets of plywood on the floor I think this is the next easiest. I used 0.7"x3.5"x10’ Primed MDF strips, super easy for the torsion box 2"x4"x8’ For the saw horses and cross brace 1/2" OSB sheet for the bottom 1/2"-3/4" Particle board sheet for the waste board. Light gray spray paint just to clean it up a bit. [PXL_20250118_22323995…

My table is designed this way, and it not only makes it possible to cut wider than the center part by a little bit, but also makes it easy for the Y travel to reach areas off of the center part by a good bit. For a full size table, I recommend this approach, and the method shown by Ryan in the one I linked above.

Another thing to consider is that extra Y reach can mean you can add screw-based clamps to the front of the table, and clamp tall objects to the front of the table, and do CNC cuts on the end of the item that’s sticking up in that usable work area.

[bernoodoo (Chris R)]

yes kinda… I used to work has a cnc milling programmer/operator so plunging your tool outside the part before cutting was the method i was used to. Not ramping into the part except when i needed to.

Maybe someone could correct me but with a router, since your part is screwed to the table and you just cut a shape into the sheet, you dont need to plunge outside the part (like with a part into a vice) like i was used to.

[bernoodoo (Chris R)]

Understood !

So keep the X axis to the minimum (in my case 49in) and maybe extend the Y axis to be able to plunge outside the sheet if I ever need to ?

[DougJoseph (Doug Joseph (design8studio))]

@bernoodoo

keep the X axis to the minimum (in my case 49in) and maybe extend the Y axis to be able to plunge outside the sheet if I ever need to

Yep. That’s how mine is setup, and many times I’ve appreciated having the Y (long axis) able to be over mid-air off the edge of the spoil board.