Hi, i am receiving my kit this week, i need to cut my emt conduits but i am not sure on the calculation website. I want the recommended size which is 24x24 outer dimensions. I don’t see anywhere the outer dimension label. What would be the desired work size for the recommended build? Thanks
if your conduits are cut to 24" you’ll get about a 12" square cutting area, slightly less if you add a vacuum attachment.
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Is it required to stay with 24 max or should i go a bit bigger?
The bigger you build it, the “floppier” it gets, so your cam has to be perfect. Stay with the recommended size for now. It’s not hard to make it bigger later.
It’s not required, but it’s strongly suggested, especially for a first build. You’ll have much more success with that size. It’s also pretty easy to change the size later by changing the conduit, belts, and maybe wiring (depending on how much you change the size).
The big question is “What do you want to do with your build?” The answer to that question will help determine the answer to your size question. If you really want to cut metal (Aluminum), then I would certainly not go any bigger than 24"x24". If you’re looking to use a drag knife to cut vinyl signs, you could make it a fair bit bigger. If you want to do some work with wood, and learn CNC, then I’d keep it 24"-30" per side. Again, the strong suggestion is to go with the 24"x24" build to start with, then see what you need/want/are willing to try later.
For the record, the single best way to get accurate cuts is to minimize the size of your machine. That reduces the flex in the system. Especially the Z axis. Keep that as small as possible, and if you must have a large Z-Axis, use extra spoil boards to bring your workpieces up as close as possible to the gantry.
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Here is additional food for thought (see links below as well). I was in the same situation as you and here is what I found.
I would suggest that the two big questions (I am just adding to what kvcummins said) are:
- What do you want to do with your build?
- Based on your personality and shop space, how likely are you to “try later” to re-size?
Let me explain. Begin, perhaphs, by reviewing my post/repsonse here (MPCNC build in Montreal, CA - #6 by thejat).
So for me, I wanted just to carve some basic signs in pine (so super fine cute accuracy may not matter as much). Also, wanted to at least create some average sized signed. So I went with a 24" x 24" work area out of the gate. All in all my MPCNC works fine/great. Although, since I added dust collection, I actually get about 600mm x 575mm which is less that 24" x 24". Hence I really did not get my originally size anyway 
More importantly, if you look at the picture of my rig in the posting above, it has an enclosure and cable chains and is in a small space. Based on that, and my personality, the likelihood of me trying again later is very small.
My point is, I think you have to consider both of the above in deciding on size. Hope that makes sense.
Thanks for the answers, it just isn’t clear what size to use since people are having no issues with 24"x24" work size. I want to start with wood only basic stuff and i will add the vaccum attachment which is making it smaller. I think ill go with 20"x20" work size and 3" Z height to start with.
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