Cutting foam sheets... with a needle!
- Thread starter dkj4linux
- Start date
moebeast
Member
Last night I was working on other things in the garage, but kept thinking about the cutter. Even with the mig tip, I still get side to side deflection. The guides you guys have developed fix the problem, but are getting complicated. This is what I am trying now:
Using the 3/4" block with a small hole at the top with the edge of the hole eased. The hole for the mig tip threaded into the bottom is only as deep as the threads. My needle is not deflecting anymore.
The tip was fairly warm after the first test, so I added some fins. They are shockingly effective. Just drill a 1/4" hole in thin aluminium, but as soon as the bit breaks through, stop and leave the bur.
Using the 3/4" block with a small hole at the top with the edge of the hole eased. The hole for the mig tip threaded into the bottom is only as deep as the threads. My needle is not deflecting anymore.
The tip was fairly warm after the first test, so I added some fins. They are shockingly effective. Just drill a 1/4" hole in thin aluminium, but as soon as the bit breaks through, stop and leave the bur.
dkj4linux
Elite member
Interesting... I was thinking similarly. Instead of sideboards or bearings, just a simple block with small, eased hole to "preguide" the needle down to the needle guide (not shown) below...
PS: I think I like your all-in-one [block] idea better however...
-- David
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moebeast
Member
I was thinking like you were first. How can I sandwich a block above and below? Then I would also need to make the printed part taller. Then the single block idea hit me. It is working great so far. My kerf is the smallest I have ever achieved.
But...but...I like the sound of the guide bearings - they add this nice "Swish swish" to the sound of the cutter in action 
Seriously, I'm all for simpler - just wish you guys had tried that a week or two ago
I was also thinking about adding some cooling fins the other day so I could eliminate the wooden insulator. But I also noticed that my mig tip is a little crooked so that's probably adding more friction as well. Going to try machining a new insulator today and will tap it properly so I get the tip in nice and straight. Then we'll see if I still want to add fins!
Seriously, I'm all for simpler - just wish you guys had tried that a week or two ago
I was also thinking about adding some cooling fins the other day so I could eliminate the wooden insulator. But I also noticed that my mig tip is a little crooked so that's probably adding more friction as well. Going to try machining a new insulator today and will tap it properly so I get the tip in nice and straight. Then we'll see if I still want to add fins!
dkj4linux
Elite member
Though I like the simplicity of the one-block approach, I'm thinking the sandwich approach might still be best for me... easier to fabricate. I think I can *laser-cut* two thinner 5mm pieces far more accurately than I can mechanically "hog out" one thicker piece with the drill press. The plastic of the cutter body will then serve as the "spacer" between upper and lower guide plates... giving it some thickness.
I'm glad to hear your cutter is doing so well. It amazes me that such a small change -- to what still so closely resembles the original cutter -- can make such a big difference
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dkj4linux
Elite member
Rather than a drill-press exercise with 3/4" material... or rasslin' with trying to cut 5mm plywood with a 2.8 watt laser... I decided to take the easy way out and cut multiple copies -- in just one pass -- of the pattern for a preguide and/or upper/lower guide out of craft sticks. I figured that laminating them and using the mounting bolts for registration would allow for sufficient alignment... at least as good as I could accomplish using another approach. Just a fit/alignment check...
I think I can make this work...
-- David
I think I can make this work...
-- David
moebeast
Member
I like it. You could progressively elongate the holes in the upper layers to reduce the bending force at the entrance of the block. It should work great. I was also pondering this morning whether we need a metal guide at all if the wood is thick enough and the hole is tight enough. It would be interesting to see how long it would last.Rather than a drill-press exercise with 3/4" material... or rasslin' with trying to cut 5mm plywood with a 2.8 watt laser... I decided to take the easy way out and cut multiple copies -- in just one pass -- of the pattern for a preguide and/or upper/lower guide out of craft sticks. I figured that laminating them and using the mounting bolts for registration would allow for sufficient alignment... at least as good as I could accomplish using another approach. Just a fit/alignment check...
View attachment 91942
I think I can make this work...
-- David
I do find it slightly ironic to build an alternative to a laser with a laser...
I currently have 7 planes cut out waiting to be put together, so I am back to my old problem of wanting to play with the cutter, but not having a reason to use it. I could make a file that just cut lines back and forth across a sheet and do durability testing on various iterations, but I don't want to listen to it for hours at a time.
moebeast
Member
I have submitted an article on my machine. I think you can see the preview at this link.
https://www.flitetest.com/articles/build-your-own-cnc-foam-cutter?preview=1
I welcome comments from you guys. I can still make edits while it is waiting for review.
Thanks,
Mark
https://www.flitetest.com/articles/build-your-own-cnc-foam-cutter?preview=1
I welcome comments from you guys. I can still make edits while it is waiting for review.
Thanks,
Mark
Looks nice Moebeast! I actually submitted one earlier this week as well and have been waiting on approval...didn't know you can share the preview links like that: https://www.flitetest.com/articles/cutting-foam-sheets-with-a-needle?preview=1
I tried to focus more on the needle cutter itself rather than the CNC...but I like your approach too! We'll see what the Monkey picks to approve - I say they both should go up
I tried to focus more on the needle cutter itself rather than the CNC...but I like your approach too! We'll see what the Monkey picks to approve - I say they both should go up
SteveRobey
Member
This is an awesome idea! How clean are the edges of your parts when they are popped out of the sheet though? I'm just wondering if for the style of airplane building we are all using if this method is better than what FT is using. The reason I say this is because when you cut foam board with a laser, sure, you get a nice clean edge on the paper, but the foam in the middle seems to tend to melt back a little bit which also encourages the paper to start peeling sooner since there is a little bit of a loose edge to the paper.
dkj4linux
Elite member
Wow, Mark! That really looks good. Seeing an actual article somehow makes all this seem so much more... official.
I can't begin to tell you how thrilled I am to see you and Jason "carrying the torch" for both the needle cutter and the MPCNC like this. Laziness and lack of imagination on my part, I could never do what you guys are doing to spread the word to the much larger audience that is out there. Many thanks and keep up the good work!
-- David
dkj4linux
Elite member
Welcome, Steve.
From the first post in this thread... and getting better every day! -- David
moebeast
Member
Looks nice Moebeast! I actually submitted one earlier this week as well and have been waiting on approval...didn't know you can share the preview links like that: https://www.flitetest.com/articles/cutting-foam-sheets-with-a-needle?preview=1
I tried to focus more on the needle cutter itself rather than the CNC...but I like your approach too! We'll see what the Monkey picks to approve - I say they both should go up
I thought you might have beat me to it, but with all the work you've been doing on the Low Rider, I figured you may have put it off.
I tried to give an introduction to the topic with links to more information. It would take a book to cover everything. I like your detailed explanation of the cutter. We could follow with a detailed article on creating files.
David, I'm glad to share, and I'm glad you like it. We got some publicity on the Angle of Attack podcast last week. I had to show my machine to Crash Hancock since he inspired me to get into CNC in the first place. He was impressed with the needle cutter.
Hey, looks like the Monkey is catching up on the article backlog - just got a notification mine went live...and see yours is too and you've got almost twice the views I do already!
I was definitely thinking about a few more article ideas - MPCNC specific, low rider specific, and file prep in detail. I just tend to prefer the forums over articles since they're more conducive to participation IMHO. But...I am thinking about a few more article ideas
and you've got almost twice the views I do already!I was definitely thinking about a few more article ideas - MPCNC specific, low rider specific, and file prep in detail. I just tend to prefer the forums over articles since they're more conducive to participation IMHO. But...I am thinking about a few more article ideas
dkj4linux
Elite member
I remember seeing Crash Hancock doing a series of videos on the Phlatprinter-series of CNC machines... really neat machines designed and kitted by Mark Carew, now of OpenBuilds fame.
I had actually proposed the needle cutter as an add-on tool head for the Phlatprinter III but Mark was already involved in bringing OpenBuilds to life... and, soon after, Phlatprinter development ceased. I have a needle cutter thread over on the OpenBuilds forum (http://www.openbuilds.com/threads/brushless-motor-foam-cutter-and-cutting-sheet-foam.5862/) but it hasn't generated much excitement lately... most folks there are not RC-oriented/focused.
I've given some thought to doing a MPCNC-style (printed parts,conduit,etc), Phlatprinter-inspired, dedicated foam-cutter CNC machine. Like the PhlatprinterIII (and the typical Cartesian 3d-printer or HP plotter), the material moves... the sheet of foam is driven back and forth by a roller mechanism and the needle cutter moves above it in the orthogonal axis. It would be a smaller-footprint machine, needing only sufficient room in front and back to allow the foam to reach the extremes of Y-axis travel... and might be useful in smaller spaces. -- David
moebeast
Member
I've listened to the back catalog of the Crash Cast twice, so I was really wanting a Phlatprinter, but it was 2015 when I started listening, so I was too late to the game.
I've thought about it myself, but getting the material to feed consistantly seems like it would be difficult. I'm thinking a lower weight version of the Low Rider might be ideal for small spaces. It wouldn't need the ss tubing if it was only carrying a needle cutter and only wide enough to cut 20-24". I'm thinking of using a cd-rom mechanism for the z-axis.
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dkj4linux
Elite member
Simplified (again!) needle cutter update
Alright! Got roped into playing golf the last couple of days and am just now getting back into needle-cutter mode
After previous fit/alignment checks looked pretty good, I fired up Inkscape and laid out and cut new guide patterns for a new and simplified cutter, along the lines of what Moebeast and I were thinking. I've created 4-layer upper and lower guide blocks, with each layer being about 1.5mm (the thickness of a craft stick). The upper guide block consists of 4-layers of progressively smaller needle holes (4mm, 3mm, 2mm, and 1mm) to create a pseudo "eased" or funnel-shaped needle preguide... and a lower guide block that has a 1mm hole in the first layer, followed by 3 layers with 5.4 mm holes for the Mig-welding tip to thread into. Upper and lower guides are then sandwiched on either side of the needle cutter body with M3 mounting screws...and no metal parts (other than the mounting screws) directly in contact with plastic.
So, I'm back to my basic cutter body with only a slightly taller back... I printed a new one. But I've misplaced my previous working cutter and can't find it in all the clutter at the moment... so will built it up and test it when I can locate all the goodies
-- David
Alright! Got roped into playing golf the last couple of days and am just now getting back into needle-cutter mode
After previous fit/alignment checks looked pretty good, I fired up Inkscape and laid out and cut new guide patterns for a new and simplified cutter, along the lines of what Moebeast and I were thinking. I've created 4-layer upper and lower guide blocks, with each layer being about 1.5mm (the thickness of a craft stick). The upper guide block consists of 4-layers of progressively smaller needle holes (4mm, 3mm, 2mm, and 1mm) to create a pseudo "eased" or funnel-shaped needle preguide... and a lower guide block that has a 1mm hole in the first layer, followed by 3 layers with 5.4 mm holes for the Mig-welding tip to thread into. Upper and lower guides are then sandwiched on either side of the needle cutter body with M3 mounting screws...and no metal parts (other than the mounting screws) directly in contact with plastic.
So, I'm back to my basic cutter body with only a slightly taller back... I printed a new one. But I've misplaced my previous working cutter and can't find it in all the clutter at the moment... so will built it up and test it when I can locate all the goodies
-- David
Hey David,
I keep bugging Mark about an OpenBuilds Phlatprinter now and then, but he seems to be too busy overall. He did release the Phlatprinter build video a few weeks ago though so I could finally see how the roller mechanism works. I still love the overall design of that machine, because one of the biggest issues I have with CNCs is the space requirement...
Balu
I keep bugging Mark about an OpenBuilds Phlatprinter now and then, but he seems to be too busy overall. He did release the Phlatprinter build video a few weeks ago though so I could finally see how the roller mechanism works. I still love the overall design of that machine, because one of the biggest issues I have with CNCs is the space requirement...
Balu
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