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Cutting foam sheets... with a needle!

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Here is the link for the instructable :
http://www.instructables.com/id/Add-an-Arduino-based-Optical-Tachometer-to-a-CNC-R/

I can't find a link to the DJI motor Im using, but here is a clone thats the same size. the shaft is threaded for their specific quad props but that actually worked in my favor- Jasons flywheel has the perfect center hole for threading that shaft on :)

https://www.amazon.com/920KV-Brushl...=8-13&keywords=dji+2212+920kv+brushless+motor
Thank you!
 
Using a servo for third axis on a foam cutter

Hi all, for those interested, I've made a branch (and a pull request) for Marlin (2.0-bugfix) with a implementation of a "servo-stepper". This allows to replace a stepper activated axis by a servo, for a lightweight depth of cut control. The PR is [2.0]Servo stepper feature.

THis would allow for example a setup like IGull's one (http://forum.flitetest.com/showthread.php?24251-Cutting-foam-sheets-with-a-needle!&p=367344&viewfull=1#post367344) to work with no GCode processing/Massaging

I will possibly try and upload a video, but for now it would only show 2 servos sycnhronously following a G0 change of position. Maybe something more spectacular in the future ?
 
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My latest creation courtesy of the MPCNC- the X-29. I’m so impressed with how nicely parts that are cut with the needle cutter go together.

A few things I’ve learned as I go:
- The mig tip needle guide apparently has a life span. After cutting about ten sheets of parts, the cutting residue (melted foam dust?) builds up in the hole and eventually binds the needle.
- I really like my needle holder but after awhile the needle can start to get loose and break. So I printed a few and now replace after 5-6 sheets.
- for me, the needle length is important. It should be barely visible in the guide on the upstroke. Any longer and the cut isn’t as clean because I guess the needle starts to be less stable the further out of the guide it goes. I’m sure all of you have figured this out already, but I’m still in the learning phase of MPCNC ops. Haha

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78843B1B-1AF8-4FA1-82F7-6E94EC924C18.jpeg
 
Progress! The Z gantry took me a couple of do-overs. Disassembling the entire X axis a couple of times encouraged me to come up with ver 1.3 where I can now just loosen the T-nuts (that I can now access) and slide it off the back plate.

Recap: I bought OpenBuilds Acro kit for $234 without motors or controller or anything. Removed 10" from the 2020 rails and used them for the Z gantry. Ordered v-slot wheel assemblies, gantry plate, etc and printed the top and bottom pieces. Everything in orange is just me quick and dirty with Fusion 360. The modification for the Z gantry was to take the plate from the kit and make a slightly larger version with 4 new holes. The acrylic was less than $2 for a 4 3/4" x 5 piece. I had to countersink the 4 original mounting holes with a forstner bit from Harbor Freight. Otherwise the wheels would hit.

The CNC control box is housing a Sparks Concepts xPro controller. Got the idea for the aviation connectors from thingiverse.com Bought them on Amazon for a couple bucks each.

If it looks too low, it's because of my future vacuum table. Cutting the grid with a dado blade also from Harbor Freight. Gluing more pieces around it to seal it off and raise it back up again. The Z has about 3.5" of travel btw. Controller is powered by a $24 PSU that plugs straight into the board after removing the excess wires. And a couple of strips of double sided tape to hold it together.

One last item, check out my R/C motor. If this works like I think it might, it'll be hilarious. Once I work up the courage to grind that protruding shaft down flux with overheating anything or getting particles in the magnets. This could be a almost ready to go needle cutter. Hole spacing is enough for .5" depth of cut. And 3 other holes if you feel you need to counterbalance. The needle is wrapped around a small bearing with 3mm ID. Also Amazon
 

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jhitesma

Some guy in the desert
Mentor
I'm not sure on the motor like that. You can't really use the other 3 holes for counterbalance because then they'll interfere with the needle.

And in my experience counterbalance is critical. I ran my original cutter with the crank style and no counterbalance for almost a year...but had to constantly adjust things as it would vibrate so much. The new cutter has been maintenance free and has been used WAY more than the old one.

You could probably put some plugs into the holes...but I doubt that would give enough mass to offset the needle and bearing.

Neat idea and looks clean...I'm just not convinced it would work well without a better way to counterbalance.
 
I'm not sure on the motor like that. You can't really use the other 3 holes for counterbalance because then they'll interfere with the needle.

And in my experience counterbalance is critical. I ran my original cutter with the crank style and no counterbalance for almost a year...but had to constantly adjust things as it would vibrate so much. The new cutter has been maintenance free and has been used WAY more than the old one.

You could probably put some plugs into the holes...but I doubt that would give enough mass to offset the needle and bearing.

Neat idea and looks clean...I'm just not convinced it would work well without a better way to counterbalance.
You could certainly be correct. My plan was to use a 3mm spacer or a 2nd bearing to stand off the needle enough to provide clearance. But I'm not so convinced about counter balancing. The needle assembly is so light to start with and there could be some mechanical advantage to it. On my MPCNC, all I did was to put another allen screw on the back of the flywheel for balance. Nothing exact. And I went through a full case of the waterproof foamboard + a lot of DTFB and never had a needle break. And the flywheel was an aluminum disc, not printed so it had some mass.

I had a lot of problems using the crank method too. Way too much flexibility. Centrifugal force throwing the arm in an even larger orbit. Not enough rigidity to give the needle the right oomph to punch through efficiently. Going to the rigid flywheel design was a game changer.

It'll be a good experiment. The 700Kvm speed and the larger diameter should provide some improvements. The whole point of this thread is innovation, right?
 

jhitesma

Some guy in the desert
Mentor
It'll be a good experiment. The 700Kvm speed and the larger diameter should provide some improvements. The whole point of this thread is innovation, right?
Yep, love the experimentation.

I did fire mine up with no counterweight when I first build the revised version. It ran...but it sure was rough. Rougher than my crankshaft version. I didn't even try cutting with it it was so rough. A small M3 screw and washer on the back smoothed it out like butter.
 
Yep, love the experimentation.

I did fire mine up with no counterweight when I first build the revised version. It ran...but it sure was rough. Rougher than my crankshaft version. I didn't even try cutting with it it was so rough. A small M3 screw and washer on the back smoothed it out like butter.
Well, if I was to disassemble the motor by removing the C-clip, which would be a little nerve wracking, I could reverse mount a socket head M3 as a counterweight.

Your flywheel was 3D printed, correct? It could be that it's too light to not balance well? It may be a couple of weeks before I can try it out. I'm going to Monterey Friday and most of this week is also busy. I'll try to get version 1.0 of the motor mount printed tonight. Then I could do some bench testing.
 
Nothing motivates me more than having someone tell me it can't be done. :cool:
So I cobbled together a quick needle cutter mount. I didn't try anything fancy because the first versions always end up in the trash and I didn't want to have to waste any more filament than I had to. Turned out my hole spacing for the mount didn't quite fit for example and I hand to ream out the holes a bit larger. Reminds me of DjLinux's early mouse trap designs.

I was very pleasantly surprised at how happy it sounded. I think that if I was to put in a set screw opposite the bearing that it'll be even happier. So this is just a large diameter 700 Kvm with the protruding shaft ground down flush with the face and a needle wrapped around a small bearing screwed into one of the prop mounting holes. It took me less than 10 minutes to tape and grind down the shaft.

I did a little cut by hand on some DTFB in the air and it was as smooth as can be expected for something held by hand. If I later determine that I need more speed, I've already sources a 900 Kvm SunnySky motor for $33

 

jhitesma

Some guy in the desert
Mentor
Glad to hear it works ironkane! It does sound a little rough to me - but that's hard to judge from video on audio. What worries me more is it looks like your needle is deflecting more to the right than the left. When mine was doing that I had issues with needles flying off and breaking. But I suspect adding some guides to it will help with that.

I'm super hyped because I FINALLY got estlcam running under wine!

Screen Shot 2018-03-24 at 11.16.41 PM.png

I haven't fully tested it...but so far everything seems to work! (that's power pods and center sections for 3 FT-Dart's on one sheet of DTFB in the screenshot!)

Woo Hoo! I can now use my favorite CAM from my macbook so I don't have to go out to my shop to do cam on my old windows machine anymore!
 
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I'm super hyped because I FINALLY got estlcam running under wine!

View attachment 104408

I haven't fully tested it...but so far everything seems to work! (that's power pods and center sections for 3 FT-Dart's on one sheet of DTFB in the screenshot!)

Woo Hoo! I can now use my favorite CAM from my macbook so I don't have to go out to my shop to do cam on my old windows machine anymore!
Outstanding, Jason. Care to detail how you did it... if you did anything different? I've tried -- though not lately -- to get it running under Wine and felt I was really not too far away... but it still eludes me. I resorted to VirtualBox and it runs fine there but I get a Windows nag (reminding me how much I hate it...) and would really love it if I could get it running under Wine ;)

I'm starting to play with a couple of my laser machines again... and playing with Onshape to get a shroud for another 3.5 watt laser I'd gotten on sale from Banggood some time ago. I'm planning to rework a CoreXY machine I had built to put it on... I've never been happy with the Z-axis on that machine. It's amazing how much I've forgotten in just a few months of relative inactivity with this stuff :(

-- David
 
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So I cobbled together a quick needle cutter mount. I didn't try anything fancy because the first versions always end up in the trash and I didn't want to have to waste any more filament than I had to. Turned out my hole spacing for the mount didn't quite fit for example and I hand to ream out the holes a bit larger. Reminds me of DjLinux's early mouse trap designs.
...
I really like what you are doing with this, ironkane. I should think we'd be hard-pressed to find a better fly-wheel than the bell of the motor itself for the cutter... this shows great promise and will get only better if it can be balanced out a bit. I recognize this is a quick and dirty first cut at a practical cutter and the needle blur is pretty wild but, as Jason mentioned, the addition of guides and a more carefully crafted needle should have this thing humming along nicely. I think you are really close to having a fantastic needle cutter. Good work!

-- David
 

jhitesma

Some guy in the desert
Mentor
Outstanding, Jason. Care to detail how you did it... if you did anything different? I've tried -- though not lately -- to get it running under Wine and felt I was really not too far away... but it still eludes me. I resorted to VirtualBox and it runs fine there but I get a Windows nag (reminding me how much I hate it...) and would really love it if I could get it running under Wine ;)
Someone on the MPCNC facebook page posted a link to this:
https://sites.google.com/site/electroniceccentricity/x/estlcam-cam-program-on-linux

Which is basically what I did. Though since this is a mac installing wine was slightly different. I followed the instructions here for installing wine on macos using homebrew: https://www.davidbaumgold.com/tutorials/wine-mac/ I already had Xquartz since inkscape uses it and installed it for me.

I tried the "normal" instructions first...and had all kinds of failure when I tried the winetricks stuff. So I fell back to the 32bit instructions lower on the page creating a new wineprefix ~/.wine-estlcam just for the estlcam installation.

I also broke up the 3 winetricks options into 3 steps in case something went crazy. But on 32 bit it went super quick and smooth (unlike 64 bit where it was crazy and wonky and took all afternoon then still didn't work.)

Once I had all that done I downloaded the 32 bit estlcam, ran it's installer in wine...then just ran wine ~/.wine-estlcam/drive_c/Program\ Files/Estlcam10/Estlcam32.exe

And boom there it was. However the fonts looked terrible. But it turned out that's an issue with Xquartz so it only affects mac users not linux users. Something about XQuarts and a font library going in different directions about how things should work. Some users suggested falling back to the previous version of XQuartz...but I worried that would break InkScape so I did a bit more digging and found that running: winetricks settings fontsmooth=rgb provides a work around. Supposedly it results in slightly soft fonts - but they look fine to me and I'm pretty picky ;)

So the big trick seems to be using a 32bit wine environment, then using winetricks to add dotnet40, gdiplus, and d3dx9_36.

I even put in my registration code for estlcam and confirmed it works. So seems like everything is good to go. It even feels faster than on my old windows computer :D

My only complaint that that the mac touchpad isn't great for it. Two finger scrolling to zoom in and out seems to go from full zoom to full non-zoom and nothing in between. So I have to use +/- to zoom instead. But my external mouse and trackball work so it's probably just a mac touchpad thing...
 
Hot dog!

Screenshot at 2018-03-25 16-53-22.png

Haven't really played with it yet but it's looking good so far :D

Used the link you provided, Jason. It pretty much went without a hitch... the 64-bit installation on Linux Mint 18. Thanks a ton!

-- David
 
Foam cutter

Hey David it's Ken you responded to a post on thingiverse today from me regarding my build video questions just want to say thanks for all the links and that I'm waiting for my 3d printer to come.once I figure out how to use it I will be back and will probably have a lot of questions on building a mpcnc.
 
Hey David it's Ken you responded to a post on thingiverse today from me regarding my build video questions just want to say thanks for all the links and that I'm waiting for my 3d printer to come.once I figure out how to use it I will be back and will probably have a lot of questions on building a mpcnc.
Welcome to the party, Ken! You'll be amazed at the wide world a 3d printer opens up. And you'll have a ball using it to build your MPCNC as well. Another link you'll want to check out is the MPCNC forum... it, too, is full of knowledgeable, helpful, folks.

https://www.v1engineering.com/forum/

-- David