MPCNC-based foam cutter system


I’m posting this to the several relevant RC forums where I’ve started foam cutter threads, to acknowledge and express my appreciation for all the nice folks who’ve commented, encouraged, shared their ideas, and contributed in any way to the development of the MPCNC-based foam cutter… and to let you see an example of just how far we’ve come over the past year.

First, I want to apologize for being so inactive lately and basically taking the summer “off”. I’ve actively kept up with all the great posts but contributed very little. Basically a lazy slob and living alone in my grandparents’ old farm house with no a/c in the Texas summer heat (hey! my grandparents did it…), I’ve been pretty un-energetic and hunkered down most of the time under a fan. But, now, the heat is starting to subside, fall is in the air (sort of…), and I’m starting to feel a bit more energetic again. So I’m now trying to un-clutter my path back to my machines and hoping to start being more active and useful again with all this foam cutter stuff.

Of note, I promised one of my two 3d-printers to my son-in-law when he got settled in a bit more, so I have recently looked into getting another one. I’ve been rather spoiled having TWO printers to work with during all my MPCNC and foam cutter builds, so I really feel I NEED two printers going forward. I’ve been entirely pleased with the $300 FolgerTech 2020 All-aluminum Prusa I3 kit I ordered and built last year, so I looked there first… it’s very well supported, there is a lengthy thread dealing with it on the FliteTest forum, and IIRC Jason (jhitesma) also has one and seems quite pleased with it. Anyway, it is indeed still available (google it… it’s the ebay listing) so I ordered another one and now have it to build. It is another of my motivations for getting my workspace cleaned up and de-cluttered so I’ll have the room to actively get back to building stuff.

Lastly, I can’t begin to tell you how excited I am about all the MPCNC and foam cutter developments of the past year… and now – cheap! – VACUUM hold-down to boot! I think the magnitude of it all really hit me when Curtis (CartCurt), over on the FT forum, posted this picture of his very impressive, relatively inexpensive, and complete foam cutter setup… that wouldn’t exist today were it not for the collective contributions of all the nice folks in the several RC forums where all this development has taken place. What hobbyist RC’er in his right mind wouldn’t love to have a setup like that? Thank you all! – David

David, just want to say thank you again for your needle cutter design and promotion of the MPCNC! I saw the MPCNC on Thingiverse a few weeks before you posted on the FT forums about your needle cutter but dismissed it. I figured it was too much printing for something that didn’t look like it would actually be reliable and usable. Then I saw your post…and honestly kind of dismissed it as well because of your love of the MPCNC :smiley:

But I kept reading because the needle intrigued me. And as I saw more of your success and others I became more interested in the MPCNC. And eventually decided I had to try and build one for myself since I’ve wanted a CNC machine even longer than I wanted a 3D printer. So after less than two months of owning my 3D printer I dug in on printing my MPCNC.

My build ( has not gone quickly. And I don’t have your excuses for my slothfulness :wink: I do also live in the desert (even hotter than TX. This summer at least one source declared the hottest city in the US to be right here in Yuma AZ) but I do have A/C. And I’ve even been running A/C in my shop all summer since my MPCNC is out there. (which is why I printed mine in PETG, though some test parts I did in PLA and set out in the sun for the summer held up FAR better than I anticiapted - only the original motor mount plates failed without serious effort to deform them.) On the other hand I do have a young daughter who takes a lot of my time and only and hour or two a night that I can get out to my shop…and the computer out there is barely capable of running estlcam causing a lot of my lack of progress.

Still progress has happened and I’ve had an absolute blast along the way. I started the project with the goal of cutting foam on 3’x4’ machine…but assembled it as a 2’x2’ first to keep things simple. Then had so much fun with it even at that size that I put off dealing with the needle cutter and expanding it :smiley: Finally got the needle going and got it expanded and now I’ve got the wonderful problem of having more things I want to cut than I have time for :smiley: Though I am still working on finalizing my own budget vac table before I really dig in.

I will take a moment to plug a few things that MPCNC and David’s needle cutter inspired me to create/modify:

My parametric version of David’s needle cutter design:

It’s still a bit of a work in progress as I’ve only got “no mount” and hicwic’s mount on it so far…but I do plan on adding the new default MPCNC mount once I get the new Z parts printed for my machine. This update to David’s design was based on feedback from several other users who confirmed David’s theory that raising the motor higher would improve the wear aspects of the needle. But I went a bit further and made almost everything about the design parameterized so people can experiment and customize for their own needs.

My square check tool:

This came from a discussion on the MPCNC FB page where someone posted a link to a similar commercial tool and I thought “Hey, that looks like it could be printed”. My design isn’t perfect, the rotating section could be done better. But it works and it made things MUCH easier for me when I enlarged my machine and could no longer just reach across to hold a tape on opposite corners.

My vacuum nozzle with offset:

I just did this yesterday. I’ve been looking for a way to hook my shop vac to the vac table I’m building without having to drill a hole in my table. On his MPCNC (the one pictured in David’s post above) Curtis used a crevice tool to interface between his vacuum and vac table - I remembered seeing a customizer on thingiverse a few weeks ago for designing crevice tools…but it always made the nozzle centered. I wanted my nozzle offset so I could lay it flat on my table. So I made a few quick tweaks to the OpenSCAD and added an additional variable allowing the nozzle to be offset. It’s not perfect - the nozzle tapers in both X and Y at the bottom so the walls get very thin if you offset it too far…but it allowed me to print a nozzle that fit my needs.

Even though I’ve done a lot with my MPCNC already I still feel like I’m just barely beginning on the journey and look forward to a long list of projects and plans that are now within my reach due to this machine.

So once again big thanks to David for his needle cutter and promotion, and of course huge thanks to Ryan for designing this thing in the first place!

Now if the weather would just cool off so I can feel safe ordering more PLA and printing the new upgrade parts :smiley:

I was hoping you would show up around here. Thanks for your work buddy. I plan on throwing one of these together this winter and cutting out some planes!!!

Thanks, Jason and Neil, for the kind words. – David

Hey all, I posted this on the vicious1 FB page but figured I’d mention it here as well.

I wrote up an instructable about the needle cutter I built for my MPCNC and entered it into a few contestson there. Instructables picked the entry to feature on their FB page, in their weekly email and on their homepage :smiley: Figured I should share it here too since it wouldn’t have been possible without the MPCNC:

BTW - Voting in the CNC contest is still open through Jan 12th and the 3D printing contest is still open for entries until the 27th. Would be fun to see a few more MPCNC projects in there to compete against

Been playing with the needle cutter again lately. Thought I’d better update this here as well :slight_smile:

First off I made a few videos on how I use InkScape and Estlcam to prepare files for cutting:


After sharing that I realized that I left out how to re-arrange parts to use your material more efficiently, so did a follow up (and switched to using estlcam 10 where I found a few “new” features that it turns out were in 9 but I hadn’t noticed.)

And one showing me setting up the machine and doing a cut, I really need to edit this down and speed up the bits where I’m not talking. And my needle cutter is starting to have some serious vibration issues - so the sound it makes is worse than normal. My hats off to anyone who actually watches this one all the way through (the main reason I haven’t finished editing it is I can’t handle listening to it!)

That last one is actually getting quite a few hits lately…and they seem to be coming from here. But I’m not sure why as I haven’t posted it yet and haven’t seen anyone else post it. If someone did share it I’d love to know were so I can join in any conversation :smiley:

Anyway…as you can tell from that last one my needle cutter has seen better days. After a year of use and about 2 cases of foam (close to 50 sheets!) the vibrations from it are really taking a toll. So I started working on an improved version. I’m switching to David’s original design with a balanced flywheel instead of the quick and dirty spring crank, and I’m incorporating a few other new designs people on the FT forums came up with.

[attachment file=38801]


  • It's taller - so the needle doesn't flex as sharply
  • It has guide bearings so the needle is already moving in a straight line when it hits the guide
  • It's shorter so there's less of a lever arm on the needle which should also minimize vibrations.
  • I'm switching to a motor that can direct mount as I've had the bayonet style mount of my current motor come loose a few times and if I tighten it enough it doesn't come loose then it binds the motor shaft - I hate those mounts.
  • The new motor is much lower kv so I can run it off 12v and still have fine control over the RPM at the speed range I run it at
  • I modeled it in Onshape so it's a little more stylish. [/ul]

    This should give me a more stable and accurate tool that won’t wear itself out as quickly/badly as the current one has.

    Here it is next to my current one:

    [attachment file=38802]

    This is still very much a work in progress. I have to reprint it tonight with a few adjustments, some of the screw holes were slightly too large, and the guide bearings needed some standoffs. I also made a few cosmetic changes:

    [attachment file=38803]

    Can’t wait to get this printed and built up to see if my changes have the effects I hope they do!

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