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Cutting foam sheets... with a needle!

Looking great David! I haven't been using my laser much because I'm a little frustrated with the G2 lens. Seems like I have a harder time cutting than people who went with the 3 element - even though the G2 is supposed to be more efficient. I'm guessing it's the slightly larger spot of the G2 that disperses the energy over a larger area. Need to pickup a 3 element to try but hasn't been a high budget priority because I decided to build a new nano quad instead. (been having a lot of fun learning Onshape and redrawing that eggbot as well as designing this new nano quad frame...which flew for the first time last night!)

I did get to give the MPCNC a bit of a workout last weekend however. My daughter wanted to have a birthday party for the two goldfish she won at the county fair last year since it's fair time again. She's not only managed to keep them alive but they've grown so much we had to move them from their 10 gallon tank to a 30 gallon. Anyway, my wife agreed to this fish party as long as it had a very limited guest list. Even so my daughter wanted to do it right. Cupcakes, a craft project (they made fishtanks out of construction paper decorated with glitter and markers), and "pin the tail on the fish" which was where the MPCNC came in :)

I found a nice fancy goldfish SVG which I used the MPCNC to draw onto a sheet of DTFB. Then made slightly smaller versions of it's tail which I used the laser to engrave and cut from posterboard. The kids loved it :D

I really need to catch up on some of my projects. Just haven't had a lot of time to get out to my shop to work on them the past few weeks :(
Thanks, Jason. It's so good to hear from you.

I've decided that Onshape is the CAD I really need to get familiar with but really haven't been able to spend the time with it that I need to. I probably need to identify an "eggbot" project -- as you did -- which would give me the excuse to spend the necessary time with it. BTW your Eggbot design might be it... I have a couple of grandkids next door that I'm sure would go crazy over it ;)

-- David
 

jhitesma

Some guy in the desert
Mentor
Re-redrawing the eggbot was a fun way to learn a lot about onshape!

I had actually tried it a few months ago but quickly got frustrated. The tutorials I was following at the time were not very good for someone just entering the solidworks/onshape style of CAD.

But then I saw this fidgit spinner from the guy who designed a 3D printed clock I made:
http://www.thingiverse.com/thing:2110472

And he had shared the link to his onshape design...so I opened it...and looking through the history on the left side to see how he made it things made a lot of sense suddenly. Then I tweaked it a bit to create these:
http://www.thingiverse.com/thing:2163765

Only took a few seconds, just double clicked on the features that created the arms, and changed how many there were. Or opened the sketch the arm feature was based on and adjusted the value for the length. Super easy!

So I spent a few evenings working through the tutorials here:
https://www.onshape.com/learn/learn-cad#

I still need to finish the last few about mates and constraints. But I got a little frustrated because the thing that tests your results is broken on almost all of the examples :( They have a post in their forum with a link to a google doc with the correct answers...but it's still frustrating to work through and be told you did it wrong. Also a few of the tutorial projects ask you to do things that aren't well explained in the associated videos.

So I dug in on recreating the eggbot as a fun way to learn more:
https://cad.onshape.com/documents/7...83a4ab88a0a85f960f/e/4351b138d554a8d00c2558a4

Finding out how to import an existing STL and pick points off of it to use as references in a sketch made it go a lot faster.

The quad frame has been a lot of fun:
https://cad.onshape.com/documents/0...ce658b6ee7b07e6791/e/6b1820b07c502b2d5d3d3fe6

I did import an existing design to pick a few dimensions off of, and took a lot of inspiration from that design on the overall shape. Still, it's diverged enough I don't feel bad calling it my design.
 

jhitesma

Some guy in the desert
Mentor
Something interesting you guys may get some ideas from:


I'm not sure what that oscillating thing is doing on their print head. My first guess was that it was embedding carbon fiber into the melt for strength...but the more I watch it the more I suspect it's (also?) leveling the layers by tamping them down as they're printed.

But the mechanism looks a lot like those tattoo guns that were discussed a month or two (or three?) ago and it seems to do a good rotary to linear motion conversion. Of course it's not KISS...but...for those who are feeling adventurous.
 
Hi, I've started tests with a needle cutter of my own (for my soon to be up CNC, see the thread), have 3D printed a mount, and tested with a crankpin setup, but the needle flies away. I'd like to test with a flywheel but wondered if there is a STL file available somewhere ?
 
Hi, I've started tests with a needle cutter of my own (for my soon to be up CNC, see the thread), have 3D printed a mount, and tested with a crankpin setup, but the needle flies away. I'd like to test with a flywheel but wondered if there is a STL file available somewhere ?
Thanks for your interest, SFReader...

Check back in this thread to post #1050... where I provide a link to the stl's and discuss printing and balancing a flywheel for use with the needle cutter. I would only use the flywheel stl from that link however... all the other parts referenced there are obsoleted. Post #1202 shows the cutter body and configuration that I am now using... but I've not yet put the stl's out on Thingiverse. I was saving that for a "rainy day" project... hey, wait! It's a rainy day today! Actually I need to round up all the files and post them... I'll probably just update the existing project with the new files.

BTW flying needles -- with the crankpin versions -- are usually due to way too high rpms. Keep it in the 6000-7000 rpm range and it should run fine... for at least a couple dozen sheets of DTFB or so. The needle will eventually wear through the crankpin and require fabbing a new crankpin so it all depends on how often you use your machine as to how long the cutter should last before maintenance is required. The flywheel should solve that problem nicely for you.

Keep us posted on your progress and I'll see if I can't get my Thingiverse "thing" updated. I'll announce it here when it's ready. -- David
 
Something interesting you guys may get some ideas from:
...
I'm not sure what that oscillating thing is doing on their print head. My first guess was that it was embedding carbon fiber into the melt for strength...but the more I watch it the more I suspect it's (also?) leveling the layers by tamping them down as they're printed.

But the mechanism looks a lot like those tattoo guns that were discussed a month or two (or three?) ago and it seems to do a good rotary to linear motion conversion. Of course it's not KISS...but...for those who are feeling adventurous.
Interesting link, Jason. It does appear the "tamper" mechanism is similar to some of the mechanisms we were looking at... but as you say, it certainly isn't KISS ;)

I think most of us who were involved in looking at the straight-line motion mechanisms all came back to the same conclusion... KISS is better, at least for our needle cutter. It was a very productive effort, however, in that we did indeed improve the cutter dramatically... attaining near straight-line motion of needle without additional moving parts. Sideboards and bearing blocks (I count bearings as "static" parts in this application) effectively reduce the number/intensity of resonances, stabilize/straighten the needle's motion before it enters the guide, and dramatically reduces the resultant friction/heat, which had been a major issue with the needle cutter in the past.

Thanks, Jason, for the video... and please keep dropping by and letting us know how it's going. -- David
 
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jhitesma

Some guy in the desert
Mentor
Interesting, RAM. I'd never seen that page, though I've Google'd for several years to find anyone else using this method to cut foam. I found only one and he was my inspiration for the foam cutter... Tom McGuire, a very talented artist/engineer, who made several versions of a foam cutting machine and to whom I'm very grateful for starting me down this slippery slope :)
Hey David, guess who just found one of my videos on my cutter :D Mr. Tom McGuire just left me a message asking if I knew of a forum where people were discussing the method - so of course I directed him here. Don't know if he'll stop by or not but it would be pretty great to have my inspirations inspiration stop by!
 
Hey David, guess who just found one of my videos on my cutter :D Mr. Tom McGuire just left me a message asking if I knew of a forum where people were discussing the method - so of course I directed him here. Don't know if he'll stop by or not but it would be pretty great to have my inspirations inspiration stop by!
How neat is that! I hope he'll stop in and let us all give him a big "Thank you" for giving us such a great gift. I tried to send him a "thank you and introduction" message and link to my thread(s) through a website he seemed active on a couple of years ago but never heard back. I'd love to have another chance! :D -- David
 

jhitesma

Some guy in the desert
Mentor
How neat is that! I hope he'll stop in and let us all give him a big "Thank you" for giving us such a great gift. I tried to send him a "thank you and introduction" message and link to my thread(s) through a website he seemed active on a couple of years ago but never heard back. I'd love to have another chance! :D -- David
Well if he doesn't you can reply to his comment on my video if nothing else ;)

https://www.youtube.com/watch?v=8GPKVmRBUm8&lc=z12jxlzq4zewjjfcz23ddlu5xuezgjaln
 
Good evening everyone, Psyborg sent me here looking for Might PM Jhitsema or Litterbug to help me out. I need a 3D printed part designed (judging on what you guys do this should take you a matter of minutes to make haha). It's a simple antenna mount and I can't really fly until I get the part printed sadly. All the specs, information, and pictures can be found at "First Build - Zap 130 Zero Racing Quad - Need Help" By Xspense

Safe Flying,
Sam
 
That's very niice

Hey guys, I'm really honored by your response to my greetings. It's really awesome to know something I did years ago had some far reaching effects. I've been really busy working with a maker space here in Wichita KS the last few years. MakeICT (.org) It's doing very well. We have a foam cutter, obviously :rolleyes:. Some fellow makers have helped create an Inkscape plugin that works with our machine that makes the whole thing almost kid friendly. It's a spin off of the old Egg bot / Inkscape setup. You can find it on github here: . I designed an Arduino shield for it. We use a servo for the Z so we can adjust the depth of cut. I'll try to get some more pictures and video up.
Any way, Great to hear back from you and I look forward to communicating in the future.
Tom McGuire
 
Hey guys, I'm really honored by your response to my greetings. It's really awesome to know something I did years ago had some far reaching effects. I've been really busy working with a maker space here in Wichita KS the last few years. MakeICT (.org) It's doing very well. We have a foam cutter, obviously :rolleyes:. Some fellow makers have helped create an Inkscape plugin that works with our machine that makes the whole thing almost kid friendly. It's a spin off of the old Egg bot / Inkscape setup. You can find it on github here: . I designed an Arduino shield for it. We use a servo for the Z so we can adjust the depth of cut. I'll try to get some more pictures and video up.
Any way, Great to hear back from you and I look forward to communicating in the future.
Tom McGuire
Welcome, Tom! I'm so glad you came by... "THANK YOU!"

For those who don't know, Tom is the originator of the needle cutter idea and served as my inspiration for all the CNC and needle cutter development I've shared in the RC/CNC forums. So we all have him to thank for this wonderful foam cutter tool that we now take for granted.

Repeating here for those who don't know... Tom first inspired me with a little pipe-framed desktop CNC machine, which I built and had a ball with... pen-plotting, hot-wire, and dremel. Later, his kinetic toys/sculptures -- and most importantly his foam cutting machines -- became my focus and off I went, embarking on what has been a very fun and rewarding journey...




I adapted his cutter to a conventional 3-axis CNC (with fully-implemented Z-axis and running gcode) and, because of my interest in RC planes (and my dislike of hand-cutting them), introduced the idea of machine-cutting sheet foam to the RC community out on the RCGroups forum in June, 2012 (https://www.rcgroups.com/forums/showthread.php?1663946-Perforator-style-foam-cutting-head). It gained virtually no traction at the time... few folks in the community were into CNC and able to see the function/utility of the needle cutter. I reintroduced the needle cutter -- along with Ryan Zellars' fantastic MPCNC -- to the RC world in November, 2015 on the RCPowers forum (their planes, PDF plans, and score/fold method were the attraction to me and perfect for the needle-cutter) and the reception was far better... though still limited to a relative few folks who were "ready" for CNC. But it was a start. I expanded the scope, introducing it out on several other RC/CNC forums, including this one, and again the uptake was "modest". The RCPowers thread continued to slowly grow, however, and then our FliteTest thread suddenly took off. Some 125+ pages in the rear-view mirror now, with folks world-wide, and about a year and a half... many needle cutters, MPCNC and others, 3d printing, lasers, drag-knives, camera sliders, vacuum hold-down, etc. have all been fair game.

Anyway... THANK YOU, TOM! I hope you'll keep coming back and give us all a chance to get to know you. Again, you may have never posted much about your work but what you did post has touched a very large community of folks.

Gratefully,

David Johnson
 
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Print Size Settings Question

I tried to set up my MPCNC with needle cutter to cut MPF which is 2' x 4' or roughly 609mm x 1219mm. I set Repetier to have a print area of X=1219 and Y=609. My needle cut well. However the last 450mm was ruined. The parts where printed on top of each other and measurements where skewed. Should I have updated the Arduino? This is the same board that came with the bundle I received from vicious1.com. If I print/cut anything 762mm x 508mm, it all comes out perfectly. I look through the forum on the vicious1 site and could not find an answer. Can any of you help a brother out? Educate me. Thank you!
 
I tried to set up my MPCNC with needle cutter to cut MPF which is 2' x 4' or roughly 609mm x 1219mm. I set Repetier to have a print area of X=1219 and Y=609. My needle cut well. However the last 450mm was ruined. The parts where printed on top of each other and measurements where skewed. Should I have updated the Arduino? This is the same board that came with the bundle I received from vicious1.com. If I print/cut anything 762mm x 508mm, it all comes out perfectly. I look through the forum on the vicious1 site and could not find an answer. Can any of you help a brother out? Educate me. Thank you!
Michael,

I notice nobody has a definitive answer for you and I'm certainly no expert but it does sound as though something needs to be "informed" of the extended X and Y you have on your machine. The Marlin firmware from vicious1.com currently has the X_MAX_POS and Y_MAX_POS set to 200 mm in configuration.h so I'm not sure why it would even work for the smaller 762mm x 508mm case (assuming you never changed it)... much less your larger one. Could be it's not responsible for the problem you are seeing but it probably would be best (less confusion?) to make the configuration.h values more representative of the physical machine... if you are inclined to re-flash the Arduino, that is.

Another thing that occurs to me: is it possible you have the X and Y values exchanged somewhere? In RH possibly? I don't know how you measured that "last 450mm" but the actual cut-area difference between 1219mm and 609mm isn't too far from that. And in your quote you specify the MPCNC dimensions as 609x1219... and then specify X=1219 and Y=609 for Repetier?

Just a thought...

-- David