Hi Joji & David,
I'm also looking at building a foam ripper of some description so that my son and I can cut down on the build time in scratch builds. I discovered this thread a few months ago and have been checking in with it now and then since. We're new to the hobby but my son's excitement as we started to maiden our first build makes me want to build more. That, and the fact that you're a true gentleman David and have inspired me to participate here.
Before I saw the needle cutter idea, I was thinking about/investigating different drag knife designs. Having done a couple of scratch builds by hand, it always seemed to me that a drag knife would make a mess of DTFB (not to mention the CNC programming complexity). The needle cutter just seems so much easier and clean.
I don't have an MPCNC and I missed out on getting one of EdwardRC's Timsav kits. I like the idea of the low rider inspired design but, not having built a CNC before, I wonder whether it's just easier to go for a full V-slot based approach for X and Y?
Also, the designs I've seen all move the entire welding tip and motor assembly up and down together, and some of the videos I've seen of these cutters in action show the needle bending to an extent, perhaps leading to inaccurate cuts. It occurred to me that you could leave the welding tip down close to the DTFB and just move the motor up and down, with the benefit that the needle doesn't bend as much? But maybe there isn't going to be much benefit to that especially if the needle extension beyond the welding tip is kept to a minimum.
Anyway, some 3D printing of parts has started while I get other bits of hardware in. With me being in Galway in the west of Ireland, everything has to be ordered in, so it's gonna take a while to get it all together.
Graham.
Thank you, Graham, for the kind words... and welcome!
As you've probably realized all these machines and needle cutters are DIY projects that can be both a blessing and a curse. No "no-brainer" kits and too many options... but also lots of opportunity to alter/explore and use whatever materials you may have on hand.
I think that as a first-time machine builder, Edward's
TimSav machine -- even without the availability of a his kit -- is probably the simplest and most inexpensive way to go. It's quite well-documented, has a large and active following (especially the FB group, which is not my cup of tea but others seem fine with it), and with enough care/patience in assembly, and possibly a mod or two from the community, this machine can be made to operate pretty effectively. There is a TimSav thread here on FliteTest that also may be of help.
The LowRider and derivatives (Moebeast's Foam Ripper, my FoamRipper/MiniFR, etc) are probably the next best machines with sufficient capacity for foamboard and needle cutting... but they (the derivative machines) are not as well documented and widespread enough to have solid community support. I've not put my latest miniFR (inspired by Geodave's rolling plotter and my previous FoamRipper) out on Thingiverse or adapted it for a needle cutter yet but if I were building a new machine, specifically for needle-cutting, I think this would be my machine of choice; i.e. it's basically just a gantry rolling on a hollow-core door and can be made as large as you like.
If you're interested, my miniFR build starts
here, evolves over a couple of pages, and ends about
here... just a few posts before you introduced yourself. My TimSav build was never constructed, complete with needle cutter (didn't need one)... I only built the basic X/Y motion machine, to satisfy my curiosity, and then built/added a second TimSav to come up with my TimSavX2 hot-wire machine, built for a specific project. It has since been dismantled.
MPCNC is always a good candidate machine -- this very thread started with MPCNC as the CNC of choice (LR and others didn't yet exist) -- for needle cutting but is a more complex and expensive build by comparison. It's generally not recommended in a larger format, sized for foamboard, but will work fine for lighter loads such as needle-cutter, laser, drag-knife, etc... much as I was using it back in the beginning of this thread. At that size, however, it does have a pretty large/bulky footprint and takes up quite a bit of valuable workshop space. MPCNC is also currently undergoing a version upgrade so there's a little bit of "growing pains" confusion and long-term uncertainty there, but, of course, all that will settle out in time. MPCNC Primo, like it's predecessors, is an amazing design and the community support is outstanding.
Of course, with the pandemic playing havoc with shipping and supply, it's a bit less predictable where best to source all the materials for whatever machine you decide to go with... but I've eventually gotten everything I've ordered online. Hopefully the same will be true for you.
Again, welcome to the party. Please let us know how we might help.
-- David