Hi! Building my first mpcnc and want to go with the recommended 2’x2’ size.
However, does this refer to the “workspace” volume in the calculator? Or is it footprint?
What would be a reasonable workspace size?
Read through the forum and found different suggestions towards the 2’x2’-reference.
Thanks in advance!
The recommended 2’x2’ would be the over-all footprint. A 2’x2’ workspace would require 36-ish inches of total length for each axis, which is near the upper limits of the “recommended” size of the Primo, before moving to the Lowrider platform. Now, this isn’t to say that folks around here haven’t made larger Primos and have them perform within their expectations. My personal build has a 2’x2’ workspace, and performs as well as I want it too. But as you get larger, your accuracy goes down, depending on what you consider accurate. If you are bent on chasing fractions of mms, then make it as small as your work will allow, but a 2’x2’ over-all machine, will operate within the tolerances expected by the designer.
My recommendation would be to start smaller, and you can always go bigger by getting longer conduit (cheap), or DOM tubing (not-as-cheap), or stainless tubing (spendy). The printed parts are the same, no matter how long your axes will be. The only difference in the printed part sizing is the diameter on conduit/tubing you plan on using.
No, the 24"x24"x3" is workspace area. That is a good starting size for wood and plastic projects on the primo. If you’re doing aluminum, or you have any special requirements, smaller may work better. Larger than about 36"x36" and the LR is a better choice.
the 24" by 24" is the figure that the default kit comes with belt for, and is the total axis span, so this would be the rail lengths. This is a working area ov about 12" by 11.75" (Assuming a non-restrictive tool like the drag knife/pen holder, or the Makita RT0701C. It is 11.75" by 11.25" working area with the DeWalt DW660
A 28" working area (About a 40" span) is the largest that is recommended without mid-span supports. I say that, but I have somehow never gotten around to installing the mid-span supports for my Primo yet, and the Y axis is 37" working area, and a 49.25" rail, but it’s never given me a problem that I’ve been able to detect. (I really need to get to installing those supports though.)
Personally, I would have found a long axis of less than 18" work area a little restricting for the projects that I’ve done. Possibly even 24" as that is the short axis of most of the relatively convenient sheet materials that I’ve found. I’d hate to have to subdivide it too much just to fit into the machine, but of course it also depends on your planned usage.
But…
Wouldn’t the pre-made kit come with enough for the recommended size?
Thanks guys! Seems to be a bit of a confusion around this, if I interpreted your posts correct?
@vicious1, any chance you could ad what you intended? 
The Kit comes with 3M of belt and that is the default size of the MPCNC calc. You can play with the numbers but it is set at about 13"x17.75" of workspace 25"x30" footprint.
Thanks for the clarification! That settles it at least for me!
I recommend thinking of what you plan to make and sizing it according to that. Remember to add and extra inch of work area to account for endstops and to give you a little wiggle room. Belt is cheap and you can always add an extra meter to the base kit. Also I find that it is easier to shorten the machine if you decide you need more accuracy than it is to make it bigger (because of costs). All that said I think a 2’x2’ work area is a good place to start (even if it is a little bigger than the standard recommended size)
Is not there a way to reduce the inaccuracy with working size going larger?
Yes, there is: Build a LowRider for bigger sizes. 
Absolutely, cut slower, reduce the load on the tool.
Going larger does not mean less accurate, it means slower.
Got it. Thank you.
Btw, talking about going larger, is there a way to go from Primo to Lowrider? Table, chart?
I plan to go for a Primo for a beginning with later upgrade in mind. I don’t need a Lowrider right now.
Thank you for assistance.
It’s planned, just not now. I want to inquiry about any concerns that may arise at that moment.