Cutting foam sheets... with a needle!

x33

Member
1> Have you won any of your RC/CNC/flying buddies over to the needle-cutter yet?

2> I'd love to see how your CNC is coming along.

3> Did you ever video you flying your needle-cut Shocky60(?) planes? If so, I'd love to see it and any photos. :D

Hi David...to start with <3>
A few weeks before a member of our club made a video in our small gym...but sadly he had the windows in the background of the plane and the bright sunlight is hitting the lens...as you can imagine ---> you can see nothing:mad:
So I will make a video by my self outdoors...but therefor I need very calm conditions...and a better show-pilot ;)
I also started to make a kind of photo story as a instruction for the assembly...but this will take some more time.
When finished, I can post this together with an additional part list and ((if you like) the DXF-file

<2> the CNC is running better than expected...even the belt drive is working very fine without any faults.
I was able to make a 2 test parts out of 5mm Alu...but this is only possible with a very low toolpath speed and multiple passes....but it works...and the 2 parts are fitting together much more better than "hand made":D
I have 2 differend z-axis to change --> one is lightweight for the needler and the laser and for a small router motor (proxon) to cut 2mm balsa --> the second Z-mount is much more sturdier and is holding/lifting a 400W spindle...which works very well (even on hard multilayer plywood ) This works with an additional y-rail to minimize vibrations.
The idea with the additional rail took some days/weeks of thinking/testing...it ihard to explaine...have to send some pics the next days.
As I mentioned before, I still running with the small stepper-drivers (30V - coming with the Arduino board) - did not found the time to connect the "real ones" (single driver board for every stepper 40V - 2,5A max)
May be I will put this on the list for "cold/rainy days"

<1> I made a flywheel for a club guy -- he build the needler quiet the same way as mine is...and is very happy whith it.
His first "project" was a smaller version of this
https://www.google.de/url?sa=i&rct=...SRo1YsKdaBETqHHcp45cGxjQ&ust=1494543715671654

At the moment, my biggest problem ist TIME:rolleyes: I'm going out for flying most the time (depending on the weather)...and I have to build up some planes for the holydays....first in the priority list ist my new DLG (Blaster3), my old one "desintegrated" while throwing (got weak after 5 years)

Greetings from Germany
Joachim

P.S.
here is the link to my club
https://www.modell-fvl.de

pics with 2 of my "fun planes"
https://www.modell-fvl.de/s/cc_images/cache_12474387.JPG?t=1473014050
https://www.modell-fvl.de/s/cc_images/cache_12474014.JPG?t=1473013060
 

rockyboy

Skill Collector
Mentor
I've been oggling these hanging CNC machines for years, and will probably build one for home CNC work now that I've let my TechShop membership lapse. I've been interested in both plotting on DTFB, and attempting a hanging needle cutter too. I know there are concerns about the accuracy level of these machines, especially closer to the edges of it's total operating space, but do me that just means build it oversized compared to the expected working surface.
 

ZeGodFaja

New member
You are a friggin huge help!!! I have been cutting planes out for years now. I figured a cnc would be too expensive to buy, especially as a now young college graduate. I have access to a 3d printer and less than 300 is definitely affordable. You are a good man and I appreciate all you have recorded here!
 

dkj4linux

Elite member
You are a friggin huge help!!! I have been cutting planes out for years now. I figured a cnc would be too expensive to buy, especially as a now young college graduate. I have access to a 3d printer and less than 300 is definitely affordable. You are a good man and I appreciate all you have recorded here!

Thanks, we're a helpful bunch. Hand-cutting planes -- and my dislike of it -- is what drove me to develop the needle cutter in the first place... that, and I was already into CNC. But having a 3d printer is IMO the real game-changer... it gives you the ability to rapidly fab and develop parts for an inexpensive CNC machine, easily capable of cutting foam and other light materials. No affiliation, I highly recommend Ryan ("allted") Zellars MPCNC (and other neat machines) if/when you're ready to take your RC scratch-building to the next level... check it out at https://www.vicious1.com/. -- David
 

DKchris

Member
I've been oggling these hanging CNC machines for years, and will probably build one for home CNC work now that I've let my TechShop membership lapse. I've been interested in both plotting on DTFB, and attempting a hanging needle cutter too. I know there are concerns about the accuracy level of these machines, especially closer to the edges of it's total operating space, but do me that just means build it oversized compared to the expected working surface.

Well....actually you just have to move the motors further out......your work surface just needs to be able to carry your raw material plus have surface for your cutting unit to rest on while cutting near the edges of it;)
I'd tend to suggest placing the motors on a "stick" hung firmly and horisontally under the ceiling, and then just have a fixed/keyed in setup for where to put the support surface on the work bench/table.

Having the pull lines hover in mid air shouldn't affect the performance at all (as they already do hover in mid air in the first place:rolleyes:)...unless off course you get caught in them doing other stuff ;)
 
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jhitesma

Some guy in the desert
Mentor
Forgot to share a few weeks ago....

A few weeks ago when my wife and daughter went up to PHX for a girl scout trip and I had a day to myself for projects I finally tackled the mid-span supports on my machine.

I had printed the parts for them a few months ago, but was putting off cutting the conduit down so I could actually install them. My hacksaw blades are trashed and doing it with a pipe cutter nearly killed my wrists the first time I cut things. When I expanded the machine I used a friends chop saw to cut the tubes - but hadn't heard from him in awhile. With the girls out of town it was a good excuse to swing by his place and chew the fat for a bit...and borrow his saw while I was there ;)

So with the tubes cut down I finally had all the bits. I assembled the first support on the front X rail setting it up so it fit snugly right next to the corner foot. Then slid it towards the middle....and....it got looser as I went....and not because it's height was shifting. Turns out my x rails aren't sagging...they're bowed up slightly in the middle. I wasn't exactly expecting that but thinking back on the issues I've had I should have been.

Debating the best way to deal with this...I should try to find some straighter conduit and recut my rails...but that's a lot of work. I'd love to get some stainless tubes and upgrade - but that would mean reprinting everything...which I kind of want to do anyway to upgrade to the newer parts...just not in a rush to do that much printing again.

What I may do for now is rotate the rails so the bow faces down since then I can use the mid-span supports to push them back up and try to straighten them. It's kind of hacky but feels like the easiest solution for now.

Oh, and the Y rails...I forgot that they sit lower...so the pieces I cut for the mid-span supports are all too tall to even fit on that axis. Need to go visit my friend and his saw again before I can deal with those :D
 

Verris

Active member
Rotating is probably fine for now, that's what I would have done. I did the same thing with my mid supports and ended up with two too tall to fit. Except I had to print new tops, seeing now my mpcnc is at the lowest height possible.
 

dkj4linux

Elite member
..having a 3d printer is IMO the real game-changer... it gives you the ability to rapidly fab and develop parts for an inexpensive CNC machine, easily capable of cutting foam and other light materials...

For those following this long, eclectic thread -- and CNC-related developments -- I've started a new thread in this same forum for an experimental MPCNC-inspired CoreXY laser engraver. It marries a 2'x2' MPCNC and CoreXY technology, as with the little rebuilt/converted Makeblock laser machine I detailed earlier in this thread... and gave me an excuse to use (justify) my new Prusa printer. Check it out:

http://forum.flitetest.com/showthread.php?35285-MPCNC-inspired-CoreXY-laser-engraver

-- David
 
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jhitesma

Some guy in the desert
Mentor
Anyone with the new style MPCNC up for testing something?

Screen Shot 2017-06-22 at 11.14.30 PM.png

Worked up a version of my latest cutter design with the new style mount. STL available here:
https://drive.google.com/open?id=0B5JVPXZ3vDfBWXJTUkFlbHRTLTA

Or if you want to export your own from onshape or tweak the design:
https://cad.onshape.com/documents/b...ba6f37764b78a0464a/e/359c102244a60c2d31d9828a

I don't have the new style Z yet so I'm not in a big rush to print this myself...and it could probably be done better. But I felt like playing around with it tonight just to see how it would go together :)
 

dkj4linux

Elite member
Anyone with the new style MPCNC up for testing something?

View attachment 89717

Worked up a version of my latest cutter design with the new style mount. STL available here:
https://drive.google.com/open?id=0B5JVPXZ3vDfBWXJTUkFlbHRTLTA

Or if you want to export your own from onshape or tweak the design:
https://cad.onshape.com/documents/b...ba6f37764b78a0464a/e/359c102244a60c2d31d9828a

I don't have the new style Z yet so I'm not in a big rush to print this myself...and it could probably be done better. But I felt like playing around with it tonight just to see how it would go together :)

Thanks for this, Jason. I have the new Z-axis on one of my machines but it's also been fitted with the Hicwic quick-change mount, so that all my lasers and previous needle-cutters fit. I've also settled, I think, on using a "sideboard"-version for my own needle cutters (https://www.thingiverse.com/thing:1211039)... it seems more stable over the whole RPM range and I like the near-straight-line motion of the needle by the time it enters the guide. The only thing I haven't done -- and want to -- is to actully print the sideboards in nylon. That's, in part, one of the reasons I jumped on getting the Prusa... I want to try my hand printing with some other materials, like PETG, nylon, etc..

My Onshape documents are about like my workspace... cluttered. Somewhere I had actually played around with my needle cutter body but I can't find it now. Anyway... I really need to spend more time in Onshape. I really like that it's so easy to add the feature refinements that make something look finished/polished, like chamfers and fillets. I've worked through several good tutorials and can make some basic designs from the ground up but my problems start when I want to take an existing STL and make modifications, as I easily can in TinkerCad. It's far trickier to work with STLs in Onshape, it seems, and I'm so "awkward" at it that, at this point, it's far easier to give in and just keep using Tinkercad. But I'm SO..OO..O jealous of you guys who now seem so much more capable in Onshape than I am. Dui, over in the MPCNC forums, has been my "hero" with what he'd managed to accomplish using Tinkercad... but even he, now, has moved on to Onshape. And I'm starting to feel left behind... like a plow-horse among thoroughbreds...;(

Oh, well... getting old is tough. -- David
 
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jhitesma

Some guy in the desert
Mentor
I'm thinking I'm going to start printing all the upgrade parts for my machine...and am leaning towards ditching hicwic and moving to the stock mount...I may try and make an adapter that attaches to the stock mount and accepts hicwic so I can re-use my laser and pen and dragknife mounts....but for the router I'm not really happy with wicwic and want something stronger.

Onshape is terrible for quickly modifying existing STL's. There's VERY little it can do with a mesh import (and STL's are a type of mesh):
https://cad.onshape.com/help/Content/mesh.htm

Once a mesh is imported into an Onshape Part Studio, you can:

Create a three point plane using mesh points
Measure the surface area, and distances to and from mesh points
Obtain mass properties for solid meshes
Project mesh points in a sketch (via the Use tool)
Create Mate connectors at mesh points
Reference a mesh point for &#8216;Up to vertex&#8217; operations (as in Extrude)

Which is pretty limited. Basically you can use the mesh points for various things and you can do calculations on the mesh but that's about it. As far as I can tell you can't actually modify the mesh in any way. You can't resize it, you can't add to it, you can't remove from it....

So for quick little changes Onshape isn't great.

What I've been doing is recreating the part in OnShape using the mesh as a reference. I want to do a video on this. If you look at that cutter project and look at some of the 525LaserMount2 part studio you can probably get an idea for how I do it. The process for that one was basically:

Create a new plane using the 3 point method and picking 3 points off the bottom of the mount portion of the laser mount.

Create a new sketch and use the "use/project" tool to pick points off the mesh that define it's outline. Then use lines, arcs and circles to recreate the outline (This is Sketch 1):

Screen Shot 2017-06-23 at 8.53.17 AM.png

Extrude that sketch. In this case I did a blind extrusion because I was trying to match the height of the needle cutter, if I was trying to recreate the original STL I'd do a "Up to Vertex" instead and pick a point off the top surface of the original mesh.

Next I created a sketch on the face where the mounting holes go and drew in the mounting holes. I didn't reference the mesh for these though, I measured the C-ToolMount part from the original MPCNC design (which you can see in another PartStudio) to measure it I had to create a sketch based off three points on the face with the holes, then picked 3 random points from each hole and used the 3 point circle to re-create them. Then I was able to click on them and in the lower right it showed me their dimensions, and I could select the bottom of the face and the center of the lowest circle to get the height off the bottom - and the centers of any two holes to get the distances between them.

So back in 525LaserMount2 I used those measurements to create mounting holes in Sketch 2 and Sketch 3 which I then removed from the mount with extrudes 2 and 3.

Next I added 2 .8mm chamfers to the top and bottom to match Ryan's original design.

That gave me a mount the height of the cutter drawn natively in Onshape. It sounds like a lot but it really only took me about 5 minutes or so.

The next part is where I'm not sure if I'm doing things right...I haven't really read the docs or done the tutorials on this kind of stuff - just sort of played around to figure it out....but...

I went back to my "cutter' PartStudio and used the derived tool to bring over the part I created in 525LaserMount2. I then used the transform tool to turn it 180 and move it into position. This is the part I'm pretty sure could be done better as I just eyeballed it - and I'm sure there's got to be a way to do that more accurately. I think adding mate connectors would make it possible but I haven't fully come to terms with mate connectors yet ;)

With the mount basically in position I then extruded the two faces next to the holes to add more support to the cutter. Then did another little extrude to fix a small gap between the mount and the big square connection in the center of the cutter.

Then I added a few fillets on those new extrusions to smooth things out.

And finally made new sketches off the faces of the mount with the holes, did a "use/project" to get the original holes in the sketches, and draw slightly larger circles around them which I then extruded as a remove from the mount to make the cut outs to allow easier access to the mount holes.

One thing I'm not happy about is that I lost the fillet on the back of the cutter - OnShape is choking on adding it back now. Really I need to go in and cleanup the feature history since I didn't draw this in an optimal manner. I should also ditch all the fillets and redo them based on the final design.

Again, this all sounds a lot more complex and time consuming than it was. I had less than 30 minutes total into adding this mount onto this cutter...and I'm still figuring out some of these tools (like the derived thing.)

The way I'd rather do this is how I did the hicwic mount....(which you can see if you go to the "Manage Versions" button in the upper right and look at the "new-mount" version of this project. There I just drew it in as part of the initial sketch that I extruded for the main body of the cutter. But I'm not sure if there's a way to "import" a sketch (like Sketch1 from 525LaserMount2) into a different sketch in a different part studio. There probably is but it was late and I was tired and didn't want to deal with figuring out how ;)

This design is really crazy overkill. The cutter doesn't NEED 6 mounting holes. And the attachments between the mount and the cutter are way more substantial than they need to be. And when I finally have my new style MPCNC parts to upgrade my machine and am ready to swap over....instead of just adding cutouts to access the mount holes I'll probably redesign the "shoulder" area of the cutter so it's narrower at the back and doesn't get in the way in the first place. I'm also worried it's probably almost impossible to install a motor on this unless you're good at building ships in bottles...so I'd probably open up the back more to give easier access to the motor mounts...though I guess you could just install the bolts from the back and put the nuts on the front so it's not that big of a deal...I just don't like seeing nuts on the front like that :D

Oh, and I didn't recreate the fillets around the mount holes like Ryan has in his design...I just forgot them last night since it was getting late.



As for other materials. I love PETG - remember I printed my entire MPCNC in it! And I really want to love Nylon...but Nylon does NOT love me :( I'll have it printing fine doing test pieces...then go to print something "real" in it and suddenly it will be underextruding like crazy again. I've tried higher temps, lower temps - no difference. I still suspect the issue is the idler on my extruder...since tightening it up solved the problem at one point. But now the problem comes and goes and tightening it further doesn't help. So I've shelved my nylon until I can build up this geared extruder and give it a try to see if it works any better for me.
 

dkj4linux

Elite member
I'm thinking I'm going to start printing all the upgrade parts for my machine...and am leaning towards ditching hicwic and moving to the stock mount...

Onshape is terrible for quickly modifying existing STL's. There's VERY little it can do with a mesh import (and STL's are a type of mesh):
...
What I've been doing is recreating the part in OnShape using the mesh as a reference. I want to do a video on this...
...
As for other materials. I love PETG - remember I printed my entire MPCNC in it! And I really want to love Nylon...but Nylon does NOT love me :( I'll have it printing fine doing test pieces...then go to print something "real" in it and suddenly it will be underextruding like crazy again. I've tried higher temps, lower temps - no difference. I still suspect the issue is the idler on my extruder...since tightening it up solved the problem at one point. But now the problem comes and goes and tightening it further doesn't help. So I've shelved my nylon until I can build up this geared extruder and give it a try to see if it works any better for me.

Jason,

I have actually imported the Roller from MPCNC for reference purposes and used "use/project" to pick off key features... holes, angled arms, etc. I'm making a 4-legged version of Ryan's 3-legged roller that will eventually -- if/when I ever get back to it -- become the lower roller part of the gantry ends for my new CoreXY laser/engraver. Suppress "import 1" and you'll see the basic shapes I've started adding to create the new part... and once I have native shapes to work with I should be okay

https://cad.onshape.com/documents/7...400aab7680b121099d/e/e44db2dcad365630a3960d1b

I also found the needle-cutter body I'd started... it isn't much and needs the sideboard tower added but it quickly gave me an idea of how easy it is to refine/polish basic shapes to look far less "clunky"

https://cad.onshape.com/documents/7...44fe8e2538eb21ba30/e/8217365f9f500541c154a356

I hope you will do that video. It's easy to get lost pretty quickly when trying to follow the verbal description of what you are doing... pictures/videos go a long way to help.

I don't really believe the Hicwic mount is the way to go now, either. Ryan's new mount is far sturdier and tool changes are not as tough as they used to be, from what I understand. However, since most of my tools present such a light load on the machine, I can still get by with the Hicwic mount and just haven't bothered to change it.

I've got a roll of PETG on hand now... for when I ever find a use for it. Actually, the 4-legged roller I mentioned above might be the perfect candidate ;)

I also got a couple of rolls of Sunlu PLA from Amazon to try... it claims to be more dimensionally accurate at +/- 0.02mm and was less than $17 a roll. I just looked and they're also now offering 1.3kg rolls for $16.55! Wow! I guess I'd better print some of it and stock up, if it's any good! :D

Thanks again. -- David
 

jhitesma

Some guy in the desert
Mentor
It's amazing how quickly I forget things anymore :(

Haven't really used the needle cutter since March or so, I have 5 planes that are almost ready or ready to maiden...and have been since March and I've just been too busy with other projects to finish them. Mini Corsair that needs a powerpod and servos (I actually need to buy servos for that one still.), my 3D printed wing that I'm just scared to fly since we don't have any grass fields here, a new mini Scout since my old one is wearing out - but I ended up just adding a new wing to the old one and it's "good enough" for now, an arrow that needs one more coat of campdry and just needs my TX programmed for it, a blunt nose versa that's been in progress for about 3 years now and is still being neglected, and an explorer that just needs to have the aileron servos installed and then the wiring done (but I'm adding a seppuku flight controller and GPS to it for semi-autonomous FPV experiments so it's a bit more complex.)

So I've kind of held off on starting any more planes :D

But...FT Cub. I love cubs. The first plane I built was a free flight balsa cub with rubber motor. I spent weeks building that thing, then finished it with tissue and dope - the classic yellow cub...though I don't think I ever got around to adding a lightning bolt on the side. Flew it in my front yard at the house I grew up in but never really got any good flights from it. Didn't have a winder for the rubber and would get bored doing it by hand way too quick so never had a good wind. Eventually I got tired of repairing it and gave up on it and dug in on a Fokker dr1 which our cleaning lady threw out when I was about 80% done because she "thought it was just a pile of scrap wood". (that was our first and last experience with a cleaning lady!)

Even so the cub has stuck with me and I've always liked them. When I picture a general aviation plane in my head...it's a cub.

Which means it's time to dust off the needle again and cut some foam!

Wednesday night as soon as I got my daughter in bed I fired up inkscape and made some SVG's from the PDF, fit it all on 3 sheets (sans pod since I have several on hand.) But by the time I was done it was too late to actually do any cutting.

Last night we had an event to attend for dinner, but as soon as my daughter was in bed I headed out to my shop. I had cleaned up out there recently but still had quite a bit of organizing to do before I could start on anything. 3 trips to the house for things I had taken inside and forgot to bring back out. But got the cutter setup and ready to go after about 40 minutes.

Fired up estlcam...and...couldn't remember if I used inside or outside operations....maybe engraving? Oh and what depths did I use? Spent another 30 minutes searching this thread to review my old posts and find out what the depths were and started creating outside cuts....but then realized I used to use engravings so had to start over again. Finally got the first sheet turned into gcode and send it to the SD card.

I have half a box of waterproof foam and with those floats coming (I built floats for my old balsa cub but never got to try them) I figure this is a good time to finally use some. But didn't want to risk it on the first cut in several months and being out of practice. So, down goes a sheet of plain foam. Ran the code and.....

Got a nice cut :)

Cutter is sounding rougher than before...I noticed some funky vibrations...looks like the motor is coming loose in it's mount so need to tighten that up before sheets 2 and 3 which I hope I can tackle tonight.

Guess I better go ahead and make a video about this process just so I can review it next time I forget how to use my own setup :D
 

jhitesma

Some guy in the desert
Mentor
Two more things I forgot....

1) Put DTFB on the machine with the bow facing down so the corners stand up and get pinned down...not bow up in the middle like I did for the first two sheets of the cub :p

2) Use .75 or 1mm deep cuts for "markings" instead of the full 2.5mm cut I use for scores...and hinges have one score and one mark. Cut all my hinges with scores on both lines and they're kind of wonky now. Will probably still work...but not ideal. Good thing I cut this one out of cheap common DTFB foam and not my nice water resistant FT Foam ;)
 

offtrolley

New member
Very interesting project and thanks to all that have posted.

Question: what is the maximum thickness polystyrene that could be cut using the needle method?

Thanks
Rob
 

dkj4linux

Elite member
Very interesting project and thanks to all that have posted.

Question: what is the maximum thickness polystyrene that could be cut using the needle method?

Thanks
Rob

Thanks, Rob, for your interest.

I don't know that anybody has actually built a needle cutter with the intent to find a maximum thickness. The development to this point has primarily focused on the sheet foams currently in common use with the RC community. Foams up to 9mm or so are readily cut with the cutters most of us have built to date.

That said, my current cutter (https://www.thingiverse.com/thing:1211039), using my printed flywheel, is usually set up for a stroke of 12mm, using the 6mm position for mounting the bearing. Moving the bearing to the 11mm position would result in a total stroke of 22mm. And I see no reason other cutters/flywheels couldn't be set up for whatever stroke you want... within reason. There's nothing truly "sacred" about the dimensions, motors, needle (piano-/music-wire) diameter, etc. so you're not out too much in terms of effort or expense if you want to scale it up and/or push the envelope at bit... i.e. it's a pretty straight-forward build.

-- David
 
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offtrolley

New member
Thanks David for taking the time to reply.
I guess I've just got to build something to test it out on thicker material
Onwards and up
 

jhitesma

Some guy in the desert
Mentor
Someone on the vicious1 FB group was asking about the process to prepare files for the needle cutter. Since I wanted to cut the floats that Sponz posted yesterday afternoon anyway....


Let's call that part one...I left out how to re-arrange parts since they fit a full sheet pretty well already. But shows the rest of my process pretty well.

I also recorded a part two actually setting up for and cutting the file on my machine...but it's 40 minutes long and mostly just the machine running - so I need to edit it down a bit and speed up the bits where I'm not talking. Unless people WANT to watch my noisy machine for that long in hopes of catching the bits where I talk in-between....