Cutting foam sheets... with a needle!

dkj4linux

Elite member
Adjusting the SCALE value in the LinuxCNC configuration file does indeed allow for "fine tuning" each axis...

My X and Y values for SCALE, in the <config>.ini file, were initially set at 80... and the units are "steps/mm".

So, commanding a G0 move for a specific distance and measuring the actual distance moved should yield an adjustment factor for the current SCALE value... i.e.

( commanded / actual ) * current SCALE​

gives a new SCALE value to be put into the <config>.ini file. Specifically,

I sent "G0 X900" and X moved just 898.5 mm, therefore the new SCALE is (900/898.5) * 80... or 80.134.

I sent "G0 Y300" and Y moved just 299 mm, therefore the new SCALE is (300/299) * 80... or 80.268.

With these adjustments, both X and Y now move the commanded distance.

-- David
 

ironkane

Member
Looks like you're having fun David. This is something that I've been interested in doing for a while.
I think you're biggest hurdle is going to be when you have to flip the DTFB over after marking/decorating one side to do your cuts on the opposite side. Mostly when your art intersects with cut lines and you don't want it to fall a little short.

Have you considered using a laser set low enough to mark but not burn enough to melt the foam or compromise the structural integrity of the paper? I was thinking it'd be faster to draw the lines and some shading and just fill in the color by hand like a DTFB coloring book.
 

ironkane

Member
All right, not having a 3D printer, where can I get the components for the needle cutter head printed? I looked at the wood needle cutter head, and I have the tools to make one, I just didn't see a pattern.
What David said. Basically, it's a L shaped bracket with a motor on one wall and a guide on the other to constrain the elliptically rotating needle. Wood is perfectly acceptable. Acrylic from Tap Plastics is fairly cheap. If you have a MPCNC, download the file and try your library or local secondary schools to 3D print. Look at my cutter on page whatever. It's about as simple as I could make it and could have done it with scrap wood.
 

dkj4linux

Elite member
Looks like you're having fun David. This is something that I've been interested in doing for a while.
I think you're biggest hurdle is going to be when you have to flip the DTFB over after marking/decorating one side to do your cuts on the opposite side. Mostly when your art intersects with cut lines and you don't want it to fall a little short.

Have you considered using a laser set low enough to mark but not burn enough to melt the foam or compromise the structural integrity of the paper? I was thinking it'd be faster to draw the lines and some shading and just fill in the color by hand like a DTFB coloring book.

It has been fun and a bit different... coming full-circle with LinuxCNC, messing with a little electronics, and thinking about cutting foam again. But this is starting to get out of my area of expertise/interest and I'm personally not going to go too much further with this. I'm totally out of the "build/fly/crash/repeat" game now... and was never one for finishing/decorating my planes anyway. So I'll leave it to folks with more ability and a greater interest in building and decorating their planes to carry on with development along these lines. Our machines are capable of a lot of really neat stuff now... and the remaining issues IMO are primarily operating procedures (registration, flipping, tool changes, etc...) and software (for generating CNC-friendly artwork). A laser offers many advantages over pens/markers, of course, but I've built enough laser machines now my curiosity is satisfied and I can see pretty much what I want/need to see using pen and paper. -- David
 
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synjin

Elite member
David,

Compulsive DIYer, yes. Simply yes. CDIYS (Compulsive Do it Yourself Syndrome) is, I think, a genetic disorder (though I hate to blame my wonderful parents). I may even have materials for projects squirreled away in at least three states...thousands of miles apart. But, I digress.

Primarily, I’d like to accurately cut those cool patterns I keep finding for RC aircraft. Secondary, I’d like to cut parts for miniature architecture (at some point I’ll probably get back to miniature war gaming). It takes too long to cut pieces compared to putting together...stuff. So, that’s the objective. If I can cut foam board and, hopefully, cardboard I’ll be a happy camper (chipboard would be a bonus). If I can replicate the work, I’ll be even happier.

I suppose I have folks I can go to for 3D printing (though I’d love to know where that metal flywheel I saw on the thread came from). In any case, I’ll get the main body of the MPCNC together, then worry about the the cutting head (the printed parts should be here tomorrow).

I plan to control it with a Raspberry Pi 3 B+ and CNC Hat. Why? ‘Cause I had the RPi and saw there was a hat (which is currently sitting in the box with the RPi). If I could figure out how to convert .SVG files to GCode on the Pi I could do everything on the Pi (Theoretically. LibreDraw can save as .SVG files.).

There is all this stuff I have. I love it when I can make something useful out of the stuff I have (or can easily get a hold of).

I’m testing the limits. Being a nubbie to CNC I don’t know all of what can and can’t be done. But, being afflicted with CDIYS I’m going to find out.

Drew
 

dkj4linux

Elite member
Welcome, Drew! Thanks for coming back :)

It sounds as though you're wanting to take almost the same path I did... and this thread pretty well chronicles my trip.

First, RC aircraft... initially I introduced the needle cutter out on the RCPowers forum... which, sadly, no longer exists. I chose that venue because the needle cutter and their "score, cut, and fold" technology seemed a great "marriage" that yielded some really nice looking planes.
Shortly thereafter, I introduced it to the FliteTest and RCGroups forums... and ultimately the FT forum is the one that really generated interest and took off. My very first post in this thread shows a couple of those RCPowers planes (F-117 and Mig-29)... along with a scaled-down FT Old Fogey, a T-rex for the grandson, examples of the DTFB cut quality, and the MPCNC I was using at the time. So, the CNC machine doesn't care whether the parts it's producing are RC planes, dinosaurs, or architectural pieces... I think we've got you're covered.

Early on, I also used the needle-cutter to cut 3mm cardboard. Check out post #907... the stegasaurus on the placemat was needle-cut. But cutting cardboard was a torture-test of sorts... it readily cut through in a single pass but an Xacto blade had to be used in places on the bottom-side to fully extract the parts. I've intended for a long time to revisit those efforts... possibly making multiple passes can improve the result.

In that same post #907, you'll see a tiny triceratops laser-cut from cereal-box cardboard (chipboard?). Shaky as I am, I put only the head together -- using tweezers to pick up and place the parts -- but I was impressed with the precision I could now get. Miniatures are not my thing but the laser is the way to go for that kind of stuff.

So, there you have it. Unless you have a 40+ watt CO2 laser -- and I don't -- papered foam is IMHO best cut with a needle-cutter... inexpensive, great detail, straight-sided cuts (no under-cutting), little/no debris generated, etc. With cardboard and chipboard, larger pieces can be needle-cut somewhat successfully but a laser is IMHO far preferable, especially for miniatures. Even a modest diode laser is a great addition to the arsenal... with patience, it can cut many materials -- sadly, not white DTFB -- but it also engraves many materials beautifully.

Finally, MPCNC is a great choice for those first steps into the world of CNC... relatively inexpensive, flexible sizing/tooling, fun and incredibly educational to build, etc. In short, it is a DIYer's dream and pretty much why this thread is so eclectic... without the flexibility MPCNC affords, much, if not most, of this stuff I would have never attempted.

There's so much more to talk about but we can save that for later. Virtually everything you mentioned can be, and has been, done... much of it routinely. And, one of the greatest attributes of automation, the time spent preparing the work for machine operations, is recouped in spades when you start making copies.

Again, welcome to the party, Drew.

-- David
 
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Antioch

Member
David,

Compulsive DIYer, yes. Simply yes. CDIYS (Compulsive Do it Yourself Syndrome) is, I think, a genetic disorder (though I hate to blame my wonderful parents). I may even have materials for projects squirreled away in at least three states...thousands of miles apart. But, I digress.

Primarily, I’d like to accurately cut those cool patterns I keep finding for RC aircraft. Secondary, I’d like to cut parts for miniature architecture (at some point I’ll probably get back to miniature war gaming). It takes too long to cut pieces compared to putting together...stuff. So, that’s the objective. If I can cut foam board and, hopefully, cardboard I’ll be a happy camper (chipboard would be a bonus). If I can replicate the work, I’ll be even happier.

I suppose I have folks I can go to for 3D printing (though I’d love to know where that metal flywheel I saw on the thread came from). In any case, I’ll get the main body of the MPCNC together, then worry about the the cutting head (the printed parts should be here tomorrow).

I plan to control it with a Raspberry Pi 3 B+ and CNC Hat. Why? ‘Cause I had the RPi and saw there was a hat (which is currently sitting in the box with the RPi). If I could figure out how to convert .SVG files to GCode on the Pi I could do everything on the Pi (Theoretically. LibreDraw can save as .SVG files.).

There is all this stuff I have. I love it when I can make something useful out of the stuff I have (or can easily get a hold of).

I’m testing the limits. Being a nubbie to CNC I don’t know all of what can and can’t be done. But, being afflicted with CDIYS I’m going to find out.

Drew

Drew,

If you are looking to build one of these let me know... I have a couple sets of the 3d printed sets done and will offer to someone who is willing to build one. I tinker with stuff & needed something to test my new 3d printer out on.. if interested drop me a msg. These are printed per Jhitesma's post & are very nicely designed.

Bob
 

IsmaelPR77

New member
Would you all say that a conical tipped needled is the best? Any other style would rip and or hang the needle up when moving in certain directions. With that being said would a long tapered point be best or a short tapered tip be best? I would assume with a long taper you'd need a slightly deeper cut stroke. Suggestions welcomed.
 

rockyboy

Skill Collector
Mentor
Would you all say that a conical tipped needled is the best? Any other style would rip and or hang the needle up when moving in certain directions. With that being said would a long tapered point be best or a short tapered tip be best? I would assume with a long taper you'd need a slightly deeper cut stroke. Suggestions welcomed.

I did a short conical tip - put the dremel in a vice and spun the needle up against the cutting wheel - and I've cut about 25 to 30 sheets without any problems or need to replace the needle yet. On through cuts, the needle goes about 1 to 2 mm into the foam spoil board.
 

dkj4linux

Elite member
From post #904, Joachim wrote...
===============
...
3) --> I tested a real sharp needle (pinpoint, like pencill) and an extrem blunt one (flat...like the bigger ones for punching holes in metal sheets) ---> after cutting some longer rows in Depron, both needle tips are looking nearly the same ( a rounded tip, not sharp and not blunt)

After all, the needle with the sharp tips is working "nicer"

This is the tips after needling the small Shockflyer and some aditional test rows

The pinpoint tip is gone...but it is still working fine

Joachim
=================

A short conical point is what I recommend and try to put on my needle.

-- David
 

Tingler

Member
I've made a little progress on my needle cutter.

Here is a couple shots of my setup and my homebuilt CNC router I'll be attaching it to.
How does the wire mount to the flywheel. It looks as if you just let it slip over the bearing and is not mounted.. how does it not fly off from vibration or movement? The photos are not big enough for me to see what's going on.
 

dkj4linux

Elite member
How does the wire mount to the flywheel. It looks as if you just let it slip over the bearing and is not mounted.. how does it not fly off from vibration or movement? The photos are not big enough for me to see what's going on.
Tingler,

I'm not trying to be mean or flippant but I admit I chuckled when I read this -- please forgive me. Quoting post #20 on the first page of a thread with 2400+ posts and 120+ pages, and then noting the photos were too small to get enough detail to see what's going on... my first suggestion is to keep reading ;)

Just six posts later, I detailed, with pictures, the very thing you've asked. I know this thread is a lengthy/difficult read and specific information can be hard to find -- and I apologize for that -- but I personally think it's a better thing to have *too much* information than *too little*.

There are numerous ways to attach the needle to the bearing...

Early on, I was grinding a very shallow groove in the outer race of the bearing... and under-sized loops formed on the end of the needle were opened slightly to slip over the bearing and into the groove, and they were held there by their own spring pressure. It actually works quite well but grooving the bearing race proved problematic for a number of people. MikeJM, who you quoted, successfully used this method... and this is the procedure I detailed in post #26.

Another DIYer destroyed a couple of bearings while trying to groove them, so he simply slipped the loops on the bearing and applied a small dab of super-glue. He then ran that needle for over a year and cut many planes.

Another machined a flywheel and embedded the entire bearing in a pocket... a crankpin/post extended from the center of the bearing and the needle was affixed. This is actually the way I would recommend if you print or machine a flywheel for needle cutter use.

Needle "keepers" have been printed which friction-fit over the outer bearing race... and the needle fab is a simple 90 degree bend, captured in the keeper. Some have made this work... others haven't.

I know it can be frustrating to find specific information buried in this thread but scores of needle cutter builds are presented -- along with many other tips and fab ideas -- so it can be very worthwhile to at least scan through the thread. Google and the forum search tools are also your friends... use them.

Best, tell us a bit about yourself and your foam-cutting plans and then ask specific questions relative to your planned build... there are many friendly and helpful folks here and they are more than willing, and able, to help.

-- David
 
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Tingler

Member
Tingler,

I'm not trying to be mean or flippant but I admit I chuckled when I read this -- please forgive me. Quoting post #20 on the first page of a thread with 2400+ posts and 120+ pages, and then noting the photos were too small to get enough detail to see what's going on... my first suggestion is to keep reading ;)

Just six posts later, I detailed, with pictures, the very thing you've asked. I know this thread is a lengthy/difficult read and specific information can be hard to find -- and I apologize for that -- but I personally think it's a better thing to have *too much* information than *too little*.

There are numerous ways to attach the needle to the bearing...

Early on, I was grinding a very shallow groove in the outer race of the bearing... and under-sized loops formed on the end of the needle were opened slightly to slip over the bearing and into the groove, and they were held there by their own spring pressure. It actually works quite well but grooving the bearing race proved problematic for a number of people. MikeJM, who you quoted, successfully used this method... and this is the procedure I detailed in post #26.

Another DIYer destroyed a couple of bearings while trying to groove them, so he simply slipped the loops on the bearing and applied a small dab of super-glue. He then ran that needle for over a year and cut many planes.

Another machined a flywheel and embedded the entire bearing in a pocket... a crankpin/post extended from the center of the bearing and the needle was affixed. This is actually the way I would recommend if you print or machine a flywheel for needle cutter use.

Needle "keepers" have been printed which friction-fit over the outer bearing race... and the needle fab is a simple 90 degree bend, captured in the keeper. Some have made this work... others haven't.

I know it can be frustrating to find specific information buried in this thread but scores of needle cutter builds are presented -- along with many other tips and fab ideas -- so it can be very worthwhile to at least scan through the thread. Google and the forum search tools are also your friends... use them.

Best, tell us a bit about yourself and your foam-cutting plans and then ask specific questions relative to your planned build... there are many friendly and helpful folks here and they are more than willing, and able, to help.

-- David
David I appreciate your patience and help. I've spent several days bouncing between google, forums and website articles..
I had to shake my head at myself for not seeing the rest of the posts.. Sometimes in the late evenings I'm already pretty tired and miss simple "next arrows" to skip to more threads or continue through posts.
Also I'm "JT" on V1engineering who's questions you answered as well. it's funny but I started on this forum and ended up on that forum... both are good info and I have a LOT of catching up to do so as not to ask question already discussed. I've done SEVERAL needle cutter searches but sometime the forum posts tend to go astray so I back out and move on to other topics...
Any way... thank you for your help... I do appreciate it...

My end all goal is foam board cutting for of course air plane building and from templates and custom builds.. totally hooked on the foam board plane hobby.. I would like to be able to custom build my own planes and not have to endless drag the exacto blade just to cut out a plane which results in mistakes, too much time. The other is I would like to be able to use a decent router to cut out various wooden ideas, gears, boxes, what ever.. All this also revolves around my kids and getting them involved and able to use the machine as well to make their creativity tangible. :)

Thanks again..
JT
 

dkj4linux

Elite member
JT, I do understand. And I'm happy to try to answer your questions about MPCNC, CNC in general, and needle cutters... or anything else we hang on our machines. That particular post just struck me as funny...

This thread is both a blessing and a curse. Tons of good stuff... but often hard to find it. So many topics have been covered that I'm not too sure it'd be any easier to find information if it was broken up into a hundred separate smaller threads... topics are often related to something else that's been discussed and "marriages" of ideas often occur. I posed the question some time back, to those who post here, whether we should start new threads each time we went off on a tangent and the consensus was to keep doing what we were doing... we were all having too much fun kicking around ideas and working collaboratively.

I certainly can't remember where stuff is in the thread [and you may know this already]... so I use the "Search" box at the top of the page. Clicking it allows you to set the search scope to "This thread" and it then returns post snippets that generally help to find the information directly... or, at least, help locate the general area in the thread where it was discussed. I use this all the time to find to find and provide links when answering questions on the forums I inhabit..

Welcome, JT. -- David
 

ironkane

Member
How does the wire mount to the flywheel. It looks as if you just let it slip over the bearing and is not mounted.. how does it not fly off from vibration or movement? The photos are not big enough for me to see what's going on.
I have some photos posted on pages 115-116 that may give you some ideas.
 

rockyboy

Skill Collector
Mentor
hey how do i connect my cutter to my cutter. what program do you use to upload files and control the printer with.

All depends on what control board you have and what CAM software you're using to convert the vector lines to gcode for the machine. In my case I'm using a control board with Marlin firmware and an SD card slot (and USB) - so I always load my gcode files onto an SD card and do my cutting disconnected from the computer. Software wise, I use http://easel.inventables.com and under the "Machine Setup" / "Advanced" options it will generate gcode downloadable files. Lots of people prefer Estlcam for the software and export gcode files from it too.
 

dkj4linux

Elite member
hey how do i connect my cutter to my cutter. what program do you use to upload files and control the printer with.
Eric,

I responded to your last request for similar information back in post #2393. I know you are new here but you really need to provide more information in order to receive the help you're looking for. Answer questions as well as ask.

I'll give you a "nugget"... the needle-cutter really doesn't need to be connected to the computer at all; i.e. it can free-run. That may not be ultimately the way you'll want it but, for now, it can be that simple.

Please respond to us. You're very welcome here and we'd love to help but you've got to talk to us. Please join in the conversation and we'll help you get going.

-- David
 

dkj4linux

Elite member
WRT FoamRipper, when I last left off, I was starting to wander off into an area I have less interest in, and practically no use for, given that I'm no longer really cutting, building, decorating, and flying planes. So, once again, I've chosen to concentrate on the machine itself... specifically, the FoamRipper's Y-carriage and needle-cutter. The current carriage was originally designed for the Phlatprinter-style machine I built a couple of years ago but, for FoamRipper, there are clearance issues with the fixed guide rods that extend down uncomfortably close to the workpiece surface. So, I revisited some of the discussion Tommy and I had, back when I had expressed interest in a more compact carriage assembly. A new carriage and lift assembly is starting to take shape and initial tests are looking pretty good.

Y-carriage.png


I printed the motor mount, a temporary end plate, and the bearing block. I also printed a series of test bearings to find the ID that gives a nice sliding fit without too much slop... and printed them in groups of four. The coupling nut and linear bearings will be press-fit into the bearing block. All the parts laid out to start basic assembly...

20190327_171310.jpg


20190327_171603.jpg


20190328_083620.jpg


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20190328_172706.jpg


Using my bench vice, I pressed the coupling nut and the linear bearings into the bearing block. There are a total of 8 linear bearings -- four each pressed into the top and bottom of the block -- to provide good support for the guide rods, which are simply 6", smooth-shanked, 5/16" hex bolts from the big box store. I then started assembling the various bearings, printed parts, and fasteners into the major sub-assemblies.

20190328_172927.jpg


20190328_173948.jpg


20190328_174019.jpg


20190328_183124.jpg


I "borrowed" the motor and leadscrew assembly from a previous carriage design and then built up the sub-assemblies on the Y-rails. I've tried to keep it as modular as posssible and easy to build "in place"... without lifting or removing the gantry from the machine

20190328_184845.jpg


20190328_211331.jpg


20190328_211345.jpg


and then tested for basic operation...


I still need to capture the bolts heads on the motor mount. of course, to insure the guide rods move with the motor and mount when lowering toward the work piece. I could always turn or cut away the heads and thread the end to look like the other end but I'm trying to avoid that to keep all the hardware as standard as possible... to make it easy to duplicate. I also need to start thinking about the lower end, where the needle-cutter and/or other tooling will mount. I also need to devise a carriage arm... to attach the Y-axis drive belt to the carriage.

But, all in all, the operation is smooth and I'm pleased with how it's looking so far.

Later. -- David