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Questions about Beam Length and Z-Axis

Hi everyone! I am considering purchasing a kit but could use a little more info from experienced users. Apologies if this information is already documented - I did some basic searching and couldn’t find the detailed answers I was looking for. Specifically I have questions about the beam length and z-axis controls. As some background, I use a small desktop 3018 so am familiar with basic CNC Router operations including the workflow (e.g. Fusion → .nc → GBRL/CNCjs software) if that matters to your answers.

I see a lot of recommendations for a 12’ motor beam to “make use of the full 4x8 sheet.”

  • Assuming I had adequate supports along the side, with a 10’ beam, will I be able to cut accurate rectangles/shapes using the whole sheet? For example if I designed a piece of rectangular furniture that used a full 4x8 in its cut sheet.
  • If not the whole sheet - any idea as to what the workable area would be?
  • Would an 11’ help or does it have to be 12’?

Regarding Z-axis…

  • Would the basic motorized z-axis control have enough accuracy to make pockets for 1/2’’ cam-lock furniture connectors or dado joints?
  • If not, would the M2 provide that level of accuracy/control?

Thanks in advance!

K Connor

the problem is that as you get into the bottom corners, the chain to the near
motor gets close to vertical, and the tension in the chain to the far motor gets
low and the chain sags more.

This has two effects

  1. the sled does not move towards the corner as well, so if your feed rate is
    too fast, the sled may not cut where you want it to
  2. the sag of the slack chain can pull the sled away from the corner a bit,
    causing ti to cut in the rong place

the longer the top beam, the better, 12’ is a convienient length to buy lumber
in and gives a huge advantage without taking a lot more space, so that’s why
it’s recommended, but anything will work. you could even avoid cutting in the
bottom corners, then flip the workpiece and cut again to use that space (if you
are really good, even having parts that are cut partially in one position and
partially in another)

Yes, all of the Z axis options are accurate (once dialed in), the ones that
(ab)use the router’s built in depth control are not as fast, and wear out
faster, but they work.

David Lang

Thanks David. That helps a lot, really appreciate it.

Hi David, is it possible to go proportionally higher and wider with the motor mounts, to lesson the effects of the outer edge extremities


Yes, play around with the numbers on the spreadsheet to see the effects.

David Lang

Thanks David, I searched and found some of the informative and interesting posts on the topic. I’m going to also do an M2 style Z axis upgrade. Is the upgrade to the due board worth the money. Any other mods I should do?

Thanx in advance