Finally bit the bullet

Well, I hit “checkout now” last night finally so now after over nine years and a half built Instructables DIY CNC I’m finally going to be machining stuff. After reading and reading and reading it sounds like I might have just opened a bigger can of worms than I had anticipated and will soon be looking at converting this into a laser cutter, needle cutter, 3d printer and pasta extruder!

I’m going to be building a hybrid table with a pop out insert piece so that I can open up a 20” x 40” opening which I’ll be lifting a carving block of ice up into with the help of a hydraulic lift cart (the blocks are almost 400 lbs!). Once lifted partway through the opening, side clamps - much like you find on a wood working bench will squeeze the block of ice thereby “connecting” the ice block to the table/gantry solidly.

Question number one (of which I’m sure there are going to be many):

I see lots of people talking about leveling the table and it sounds like it’s a critical thing. I guess I kinda understand that although if the table and gantries are square and parallel to each other, should it matter if it’s all level? I also saw mention of slanted tables - one I think was 70 degrees! So where does the “level” discussion come into play there? I ask because I’m wondering how precisely I’ll need the block of ice “leveled” in the opening or can I use the CNC to make the flat surface for me before the milling really gets underway?

I also plan to make the table portable and stow able - not a ton of room to spare in my shop. I saw a flip-up roll away table last night which I think I can adapt. I do wonder though if I can leave the MPCNC all set up on the work surface if it’s to be tipped on its side for storage repeatedly?

I’ll stop there for tonight. I have some serious cleaning and reorganizing to do in my shop before the big box of goodies arrive.




Just know that the work area is not centered between the feet. The tool is offset to one side, so there work area is too.

I think that’s a new one. I can’t wait to see how it works. How do you keep the I’ve from melting while milling it?

Level is just shorthand for all that. The machine should Be pretty close to square, and the gantry needs to be close to in a plane. The bit needs to be perpendicular to that plane. Then, the workpiece top surface needs to be parallel to the plane (which you can achieve with surfacing). Then you can go carve something perfect. In reality, everything has tolerances and if you’re cutting through, a lot more error is tolerated. If you’re carving, then the surfacing matters and the rest isn’t as important. It’s easier to say “level” than all that.

What does matter w.r.t. level is that the machine is designed with gravity pointing roughly down. If you had it really tipped, then you’d run the risk of backlash in the Z screw, or maybe something else.

I think it’s probably ok, but I’m not a Mechanical engineer. Someone a while ago attached a winch and lifted it off of his bench up close to the ceiling to get it out of the way. That seemed like a clever idea.

What Z height are you thinking of wanting?

Dang Heffe nice reply, my thoughts exactly!

Kelly, can’t wait to see the first MPCNC ice sculpture and make a new category in the gallery. The router blows some heat so you will probably need to rig up a little deflector, but no big deal.

All the questions get a lot easier after you have used your build once or twice.

If I need 20 X 40 centered (because it’s easier for me to wrap my head around when building the table) how wide and long do you think I should plan my table / mill? I was sorta thinking it’d be in the neighbourhood of 48" X 28"?

I’ll be making the table portable so I can move it outdoors during our winters (it may even be hauled out and about to festival jobs if it works really well). That and a good stream of air from a blower or compressor and I should be able to keep the heat from the tool away.

Oh man…if you could see the way the roof my shop ALREADY looks…but you triggered another thought. I’m also a very active chainsaw carver which means loads and loads of dust in the shop. Should I sew up a fabric cover to keep the rails and belts etc under cover when not in use so we don’t get major dust build up? (I feel like there’s an obvious answer here…)

I think I can get away with 6". It depends on what I end up doing with the mill ultimately. If I just want to use it for logo engraving 5" would be fine but if I’m clever about things I could technically use it to do full carvings - I just need to flip the block after carving the first side. The blocks are 10 inches thick. And you KNOW I’m going to try it eventually so I might as well plan for it…hahaha.

I use a 5" long, 1/2" end mill by hand currently in a Makita GD 0600 Die Grinder. Then I have shorter, finer end mills for the details…smallest is 2.5" long, 1"8" diameter - all 1/4" shank. I figure if I keep the feed rate low and overlap high (not sure if that’s the right terminology) and go in just 1/4" per pass It should work okay. There isn’t a lot of resistance unless you’re really bearing down on the tool. I can plunge the full 5" into a block and wind it through in all sorts of shapes and it works. It works the tool hard but it works without too much physical force.

FYI - there is a commercially sold ice CNC out there…for a mere $20,000…

I’ll try to attach some of the hand carved logo pieces. The colour fill logos are a multi step process but I think I could wrap my head around how to do it with he MPCNC. The white (snow) filled one is after about six hours indoors, melting away.

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Too cool!

Literally. Ha!

This is really interesting. I had no idea such a process existed.

I know that a 5"x1/2" bit in wood would be a disaster, but if it’s OK in ice, then great! I suppose you’ll have a much lower fire risk :D. Generally with the MPCNC, you can go as big as you want, but the less you know about CAM and the farther you get from a 24x24x3ish size, the harder it is to get good results. You’re definitely on the brisk, icy edge with this, but we are cheering you on, for sure.

The other powerful thing about the MPCNC is it doesn’t take long to “edit” it to change the size later. So learn, share, edit, repeat.

w.r.t. the asymmetrical build area, you can see what I’m talking about in a pic like this:

The center gantry will bring the bit almost all the way to the inside of the left feet (and front feet) and it’s got that whole 4" or so on the right and back.

If you use the calculator to determine the overall size of the machine, given you want a 20"x40"x6" build area, and then you cut the opening just inside all the feet, you’ll end up with something like 24"x44" opening, and it doesn’t really matter what that area is, just remember to clamp your ice to the front left corner, and you should be pretty good. The bit definitely can’t hit the feet, so that’s where I’d start, and it may still be 1/2" or so away from the feet, so I’d plan to add some spacers, or otherwise adjust that after you’ve got it built. It’s not rocket surgery, but I’d hate for you to make something Per-Fect and then have to destroy it because you didn’t realize there was an offset.

I’ve seen some pretty dirty rails, and they don’t seem even a little bit bothered by them. The lead screw is going to need some lubricant, so that might be one spot where really fine dust could get stuck, and then jam, but the rollers are pretty tough. I don’t want to spread paranoia, but my first thought is that the bearings will be upset if they get wet. This is just based on my experience playing inline hockey around water, they can rust, and then start sounding pretty crunchy. Granted, my frame on 8 tiny wheels is a lot more stress than the trim router on 50 bearings. Using compressed air to redirect the “chips” could help, and if you get rusty bearings, then you’ll have to cough up the money for good sealed ones. The bearings aren’t the hardest thing to replace.

Shop tours are always welcome :slight_smile: I bet you’ve got a unique space.

Sweet! Used to go see ice carvings every winter when I still lived in Fairbanks. If you use one of the dc spindles instead of a dewalt, they don’t blow as much air on your workpiece. Just a thought.