What is a good Z-axis size?

Mostly Printed CNC - MPCNC Troubleshooting
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Hey there. I have printed all of the parts to get my MPCNC up and running (I have an xyz davinci jr printer). I am getting ready to start my build (have to schedule a day off work. Having 4 young children leaves me no free time). I was hoping to have an x/y build volume (useable) of 20"x30" (size of adams foam board). Was hoping to either one day setup a drag knife system to cut the boards for me (RC Aircraft) or at the very least draw cut lines. I have purchased Ryan’s extruder and was hoping to run the mpcnc as a 3d printer (with hopes to build his new i3 style printer in the very near future, as I ended up with 10 stepper motors in the process of getting things ordered - lets just say ordering parts after you have had a few drinks…).

Anyway, I am curious as to what is a good sturdy build height for the Z-axis. I am thinking in terms of 3D printing here. I do not want to limit myself on my build volume if I can help it (then again I plan on building his 3D printer in the future). I plan on using this guy to print the parts for the 3D printer then swapping out the extruder for a spindle (probably the recommended dewalt). I never plan on cutting much more than some light wood/plastic for making panels for projects and such. I know going to large with your Z-axis can cause issues with milling. I was hoping someone knew the ‘just right’ value.

I was thinking maybe 6"? is this too much if I plan on running the dewalt later?
Another question I had was will I need to support the Y axis at the length I am planning?
I have already printed the 1/4" threaded support (http://www.thingiverse.com/thing:1160962) just in case.

Thanks for any suggestions you have to offer. Having little free time I just want to make sure I am doing it right the first time :wink:

Neil

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The issues we face having a multi machine! Good problems though.

Here is what I say, since it sounds like you are going to kind of do thing sequentially. Build it just a bit taller than your tallest part to be printed since you know what you are making. Then you will have a printer, and can make the MPCNC shorter if you need to. If you make my thhingiverse printer I am pretty sure the tallest part is 2.75". If that is the case I think you would be great to leave it at a 3-5" Z. Most bits won’t let you cut more than about 1.5" max so the rest is just for material clearance.

I don’t think you will need the midspan supports but they can’t hurt.

As for those foam panels, one of our uses has been pretty successful with a tattoo style needle cutter. https://www.google.com/search?q=mpcnc+foam+cutter&ie=utf-8&oe=utf-8

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Ryan,

Thank you very much for the information. I will probably go 4". I love the link you provided to the foam cutter. What a great idea! I have plenty of spare rc parts around to throw something together. Thanks again for the wonderful design and for providing us with all of the information and files to allow us to create this amazing multi purpose machine! I may end up just printing the parts off on my da vinci jr (plastic needed for your 3d printer) and skip throwing the extruder on the mpcnc (just go right for the dewalt). We will see. I have another roll of pla getting delivered Wednesday (hatchbox silver). I may go with a black and silver design for your 3d printer.

Take care,
Neil

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Can’t wait to see what uses you find for it!