height for CNC/3DP

i see in the faq that the max height for the z axis when using an MPCNC as a 3dp is about 12 inches, is that an ideal height? or literally the max? I am looking to build a CNC but i really want to be able to use it as a dual CNC/3DP, however im not opposed to only having maybe a 10" z axis if that would be significantly better than 12.

Also, when i put in the z axis at 12 with the dimension calculator it says that my legs should be 11.5 inches tall. That seems a bit too tall for the router to work correctly? maybe not?

I guess what im asking is this:

If i make a CNC/3dp with a usable area of 24/24/12, the dimensions the calculator spits out is 34.4x34.4x19.5, will this work fine for the CNC part, and will the 3dp still be able to print at a reasonably fast speed, say 80-90mm/s along the x/y axis? (thinking of cura where speed settings for infill seem reasonably fast and i get decent prints at 60-90 for me on my anet a8)


also want to mention for 3dp i plan on using a bowden setup

Nope. Mixing a giant printer and a cnc router does not work well.

The tallest you should go with a router is 4" less is better.

90mm/s is extremely fast for a 3D printer. I generally print from 30-35mm/s.

ok. so i really do need to decide between a router and a printer then lol.

so in your video where you switch out the router for the printhead (the cup of coffee one), thats not really feasible? or are your prints on that machine just really limited in height?

yeah 90mm is pretty fast and tbh my anet is probably not getting near that speed, that’s just what i have been setting it to, i think its actually limited in firmware somewhere.

No but how often do you think you would ever print 12" tall? You can have a giant printer just not a tall one. Apache’s video is very common, most of us constantly swap the head. No other tool needs more than an inch or two of travel other than a very tall printer.

For milling speeds are very critical and running off the firmware limits is not going to be a successful strategy for you. There is a noticeable difference between 12 and 14mm/s when milling. As a matter of fact the new updates to the firmware tend to crash the machine if you don’t keep your speeds in line.

first, thanks for your help and your replies, i expected not to get much out of this question and you are being very helpful

honestly i dont think ill print 12" very often at all, however i can see myself printing more than 4" regularly. id think 8 would be about right. Honestly i see myself printing more than using it as a router, but id like the option for both (im a cheapass and for now i dont want to have to buy another control board, stepper motors, etc if i can make a machine that will do both functions).

would it be feasible to build one of these that can print up to maybe 6 or 8 inches high but still do a decent job as a cnc router? or is that out of the question as well? 4 inches of print room just seems really short. what about if i had a table where the bottom dropped down a few inches when i wanted to print? thought i saw a build like that on here. is that possible?

sorry to ask so much, im just really trying to understand what my limits are, and what i can do here.

If you are milling foam you will be fine, wood-maybe, plastic-doubt it, metals-no chance. Very large very expensive mills generally do not even have 8" of Z. It is really just a physics thing. The forces involved in cnc routing are much much higher than printing. You have to make a choice.

This is a cnc router that can easily 3D print,and do many other things within a size envelope. If you want to build it as a giant printer then is pretty much all it is good for. There are lots of giant printer builds but that is all they want them for.

Have a look at some of the videos and take a look at the build volume on some of these, and know that most of these people have rebuilt the machines to suit their needs, after trying to go giant in all axis.

The smaller it is the more rigid it is, the faster you can push it. 24x24 is big to learn with.

so if i wanted 8 inch z axis, but also wanted to be able to cnc cut wood, what would be good x/y dimensions?

I’m not able to give you numbers like that. I don’t think you will enjoy using this as a router with an 8" z axis.

You should chose one or the other, both is not a good solution. Choose a main purpose and build to that, then see what you can do as a secondary function.

alright, sticking to your guns on this i see :smiley: . i will go with a router as primary, 24x24x4. i can always rework the z axis if i feel like testing it higher, or if i decide that i really wanted a large 3dp… for now though, router it is. Most importantly though, thank you for the help.

4 inch high is good right?

Yup, good luck.

You’re not really forced to chose between CNC or 3D printing applications.
You can do both if you have the right table.

Take a look at my setup, it works fine for 3D printing tall objects and for milling while keeping a rigid setup.

Here: https://www.v1engineering.com/forum/topic/my-mpcnc-made-in-china/

You can adjust the table height and you just have to build two different Z axis: a tall one for 3D printing and a short one for milling.

Milling position:

Giant 3D printing position:

nice, i thought i saw this on a build, this is the one i meant. i will follow in your footsteps on this, and make 2 different z axis, i have an extra stepper motor anyway since i had to buy in sets of 3. thanks to both of you for your help

I’m sorry intrude, but have to ask something related, i saw that you suggest start the machine with x30in and y30in of usage space or its the size overall, 20inches of usage space and 10inches for the machine use?