Cutting foam sheets... with a needle!

[iGull]

Neil,
That is the cleanest and simplest foam cutting machine I've seen yet. Many have tried, some have succeeded, but you have killed it.
I am guessing your machine would cost around $250 to replicate?

Thanks, it still has lots of issues that I'd like to fix - however, that gets you into the realms of over-engineering things and it works perfectly ok for now

250 USD would be about right for what I have.

I think Quimney mentioned that he had regular alumin(i)um extrusion, I bought a large bag of wheels from China for that same purpose - same wheels that they use on those el cheapo Chinese CNC machines - would be perfect for something that hangs from the wall using maybe 20mm^2 extrusion - think it was from Aliexpress - if there's interest, I'll rake out the invoice.

Cheers

Neil

 

[iGull]

I have been wondering about an arduino-like "disguising" as a stepper driver (using the same connections step,dir, 5v Gnd) and piloting a servo for the Z value...
Even better would be to update the marlin software and transfer Z moves to servo positions (and simulate endwitches) piloting the servo pins on the ramps board...

That would allow use of "lightweight" cutting/tracing heads on the common Platform...

I had given thought to all those ideas strangely ) However, in the interests of simplicity (that's simple for me, not necessarily for everyone else), I went the modified gcode text route.

While it's very easy to drive a stepper from a wee Arduino, and equally simple to test for step and direction from the controller , the issue is the speed of the RC servo (it's not a _real_ servo - as in dc motor mit encoder), it's fixed. You would have to insert a fixed/variable delay into the data stream from marlin (if that's what you are using). You are also adding cost to complexity by adding (albeit cheaply an Arduino.

Updating the marlin software (which is probably what someone should do for machines like this anyway - create a fork from marlin with a reduced interface) would be a better idea, but it still has the same issue as above.

By editing the gcode, you can simply stick a regular RC servo on a regular ramps board using regular vanilla marlin firmware and work your way around all the above issues - not the neatest approach, but as I said before, it's not for SpaceEx employees )

It would be easy enough to write something that parses the gcode to give what's required - there are a couple of gotchas in that everyone's Z heights will be different most likely, but that can be worked around.
I'll have a look at that today if it's not flying weather- it could be less labour intensive for me and it is prone to human error
It would have to be a Mac application of course LOL )

Cheers

Neil

 

[TheSFReader]

I had given thought to all those ideas strangely ) However, in the interests of simplicity (that's simple for me, not necessarily for everyone else), I went the modified gcode text route.

While it's very easy to drive a stepper from a wee Arduino, and equally simple to test for step and direction from the controller , the issue is the speed of the RC servo (it's not a _real_ servo - as in dc motor mit encoder), it's fixed. You would have to insert a fixed/variable delay into the data stream from marlin (if that's what you are using). You are also adding cost to complexity by adding (albeit cheaply an Arduino.

Updating the marlin software (which is probably what someone should do for machines like this anyway - create a fork from marlin with a reduced interface) would be a better idea, but it still has the same issue as above.

By editing the gcode, you can simply stick a regular RC servo on a regular ramps board using regular vanilla marlin firmware and work your way around all the above issues - not the neatest approach, but as I said before, it's not for SpaceEx employees )

It would be easy enough to write something that parses the gcode to give what's required - there are a couple of gotchas in that everyone's Z heights will be different most likely, but that can be worked around.
I'll have a look at that today if it's not flying weather- it could be less labour intensive for me and it is prone to human error
It would have to be a Mac application of course LOL )

Cheers

Neil

Oh, yes, clearly a gcode post-processing is WAY simpler... Just read the G01-04 commands that relate to Z, and translate them to servo settings(with some dedicated calibration parameters for the "real" Z-min-z-max depth vs the "servo" ones) ).
Only problem is if the CAM mixes Z move instructions with XY , in which case the servo would be out of sync...
It that doesn't happen, the fixed servo speed won't matter either.

But ovarall, you're right, the gcode processing is way easier

 

[TheSFReader]

Updating the marlin software (which is probably what someone should do for machines like this anyway - create a fork from marlin with a reduced interface) would be a better idea, but it still has the same issue as above.

Ah ! Found the right place to update Marlin : would probably be in stepper_indirection.h / stepper_indirection.cpp (+ probably a configuration.h flag and its dependencies to add...)

 

[Nactan]

I've been trying to get my foam cutter working for 2 months now. My problem is that the needle keeps breaking. I'm using the flywheel version with the needle keeper and 4 bearings for centering the needle. The needle breaks right at the bottom of the needle keeper. I tried moving the mounting hole for the needle keeper closer to the motor shaft to reduce deflection but the problem persists. Has anyone else had this issue?

 

[quimney]

I think Quimney mentioned that he had regular alumin(i)um extrusion, I bought a large bag of wheels from China for that same purpose - same wheels that they use on those el cheapo Chinese CNC machines - would be perfect for something that hangs from the wall using maybe 20mm^2 extrusion - think it was from Aliexpress - if there's interest, I'll rake out the invoice.

I would be interested in what you found, I was planning on either printing or turning them... maybe both, but these might be cheap enough to convince me spend my time on other things. If it's not too much trouble send me a link

My extrusion is 24mm^2 so we are in the same ballpark.

 

[moebeast]

I've been trying to get my foam cutter working for 2 months now. My problem is that the needle keeps breaking. I'm using the flywheel version with the needle keeper and 4 bearings for centering the needle. The needle breaks right at the bottom of the needle keeper. I tried moving the mounting hole for the needle keeper closer to the motor shaft to reduce deflection but the problem persists. Has anyone else had this issue?

That happened the first time I tried the needle keeper idea. I shorted it down a bit and it worked for me. The smaller one is the one I published.
What is the distance between your guide bearings and the motor axis? Mine is 56 mm.
I would also add a drop of oil on the needle bearing.

 

[Michael9865]

Neil and Rockyboy - Your Lowrider type designs are looking great and very tempting to try. I don't think that I could fit another machine in my hobby room. Hmm

Jason - Did you make a copy of your 525 Improved Needle Cutter to fit a EMAX CF2822 1200KV? I think the mounting holes for the motor are different and I think it has a longer measurement from the back of the mount to the needle. If you didn't, would this motor work with the current measurements, http://www.valuehobby.com/e400-1000kv-outrunner.html ?
(FYI - I tried to stretch the stl after importing it into SketchUp and I did not come out well. LOL My skills are lacking.) Thank you!

I am almost finished with the updated Z to my MPCNC. I am at the alignment/squaring stage in the installation. I forgot to get a picture of it before I came into church today. I figured I might as well update to the Improved Needle Cutter also, since I have the bearings and hardware already on hand. I am also going to update from LiPo powered to a dedicated 12V Power source for the cutter.

 

[Nactan]

That happened the first time I tried the needle keeper idea. I shorted it down a bit and it worked for me. The smaller one is the one I published.
What is the distance between your guide bearings and the motor axis? Mine is 56 mm.
I would also add a drop of oil on the needle bearing.

I took Jason's 525 mount and modified it to work with the CF2822 motor. I think the distance from center of motor shaft to center line of the first bearing is 62mm.

 

[TEAJR66]

Neil and Rockyboy - Your Lowrider type designs are looking great and very tempting to try. I don't think that I could fit another machine in my hobby room. Hmm

Jason - Did you make a copy of your 525 Improved Needle Cutter to fit a EMAX CF2822 1200KV? I think the mounting holes for the motor are different and I think it has a longer measurement from the back of the mount to the needle. If you didn't, would this motor work with the current measurements, http://www.valuehobby.com/e400-1000kv-outrunner.html ?
(FYI - I tried to stretch the stl after importing it into SketchUp and I did not come out well. LOL My skills are lacking.) Thank you!

I am almost finished with the updated Z to my MPCNC. I am at the alignment/squaring stage in the installation. I forgot to get a picture of it before I came into church today. I figured I might as well update to the Improved Needle Cutter also, since I have the bearings and hardware already on hand. I am also going to update from LiPo powered to a dedicated 12V Power source for the cutter.

It just so happens that I built this needle cutter around that exact motor. I copied the other designs here and made a few tweaks.



The files are available on Thingiverse. https://www.thingiverse.com/thing:2544466

You can also get the Sketchup files from the 3D warehouse. https://3dwarehouse.sketchup.com/search.html?backendClass=both&q=needle cutter

that is a .030 welding tip. Right now I am using .020 wire. No heat buildup. I did a little DTFB cutting by hand because my MPCNC is not operational yet.

 

[dkj4linux]

It just so happens that I built this needle cutter around that exact motor. I copied the other designs here and made a few tweaks.

View attachment 94970

The files are available on Thingiverse. https://www.thingiverse.com/thing:2544466

You can also get the Sketchup files from the 3D warehouse. https://3dwarehouse.sketchup.com/search.html?backendClass=both&q=needle cutter

that is a .030 welding tip. Right now I am using .020 wire. No heat buildup. I did a little DTFB cutting by hand because my MPCNC is not operational yet.

Very nice!

 

[Michael9865]

I took Jason's 525 mount and modified it to work with the CF2822 motor. I think the distance from center of motor shaft to center line of the first bearing is 62mm.

It just so happens that I built this needle cutter around that exact motor. I copied the other designs here and made a few tweaks.

The files are available on Thingiverse. https://www.thingiverse.com/thing:2544466

You can also get the Sketchup files from the 3D warehouse. https://3dwarehouse.sketchup.com/search.html?backendClass=both&q=needle cutter

that is a .030 welding tip. Right now I am using .020 wire. No heat buildup. I did a little DTFB cutting by hand because my MPCNC is not operational yet.

Thank you both. My skills are really lacking when it comes to this stuff.

 

[moebeast]

I took Jason's 525 mount and modified it to work with the CF2822 motor. I think the distance from center of motor shaft to center line of the first bearing is 62mm.

That should work. I just uploaded a modified holder with less mass and a taper where the needle exits the holder. I added an 8mm bearing version as well.

https://www.thingiverse.com/thing:2429886

 

[jhitesma]

I guess I need to do a modified version of my latest design that's a bit more flexible on which motors can be used.

That emax motor looks close...but it doesn't have the screw holes in the front I use to mount the flywheel - so it needs to use a "servo saver" style flywheel mount and those stick out more which my design won't currently accommodate.

The motor I'm using is 27.75mm from the rear mounting surface to the front face (not counting the "nose" around the shaft):



The good news is it's a common size motor. The problem is I didn't realize how few of these motors have the threaded holes in the face for mounting a prop shaft Turns out even some of the other motors I have this size that I thought would be suitable lack those holes.

It's fairly easy to adjust my design to accommodate a different length of motor.

1) Find the "Base" sketch in the features list:


2) Double click it to open it and press 'n' to view it's plane "normal" to your window:


3) Double click on the measurement between the needle hole and the back to edit it:


4) Enter your new measurement, Say 42mm (and keep your towel handy ):


5) Click the green check on the feature details pop-up to confirm:


6) Enjoy your new resized mount:



You can then right click the "new-mount" "part" in the parts list and export it as STL to print!

Note - this does have limits...if you resize it too much things can get wonky...here's what happens if you increase it to 50mm for example:


It's probably still usable...but not quite as intended, those overhangs may be tricky to print at that point. The problem is stretching it that much throws off one of the other features - you can look for red features in the features list and try to recreate them in a way that works...but that gets more complex. It would probably be easier to just eliminate the cutouts at that point - which would just require selecting them in the features list and hitting delete. I've named most of the features so it should be relatively easy to figure out what's what.

If anyone is interested I could try and do a video demonstrating how to make this kind of change.

 

[ironkane]

That is a truly great design. I've been wanting to move from my MPCNC to a OpenBuilds frame and this is a gift from on high. That Z axis is amazing. Do you have any drawings that you'd be willing to share? I doubt I could come up with a better one on my own.

Hi

Thought someone might be interested in my new setup for cutting depron, none of which is particularly new, but maybe a slightly different take on things.



If you have any questions/comments feel free to keep them to yourself LOL )))

Thanks to all who have posted info on this forum thread that made my life a wee bit easier - you know who you are

There’s also a vid here on youtube …

https://youtu.be/bY4YnIyu8cE

Also just noticed (too late sadly that Barton Dring across on buildlog.net has created a driver board designed for drawing machines/lasers etc - uses grbl, but the neat thing is that it is designed to use a servo for the Z axis - as in some of the drawing machines (polargraph etc if you have seen them).

Apologies for the lengthy post.

Cheers

Neil

 

[iGull]

Cheap Aluminium Extrusion Wheels

I would be interested in what you found, I was planning on either printing or turning them... maybe both, but these might be cheap enough to convince me spend my time on other things. If it's not too much trouble send me a link

My extrusion is 24mm^2 so we are in the same ballpark.

Hi

Here's the wheels I got - they're on the ebay.co.uk website, but I assume they'll be available worldwide...

http://www.ebay.co.uk/itm/12pcs-HR-...728852&hash=item43e1281142:g:Si4AAOSwT6pVzzNN

Cheers

Neil

 

[iGull]

DepronCNC Laser Parts

That is a truly great design. I've been wanting to move from my MPCNC to a OpenBuilds frame and this is a gift from on high. That Z axis is amazing. Do you have any drawings that you'd be willing to share? I doubt I could come up with a better one on my own.

Hi

All I have are the laser parts, I've attached them in *.pdf format. The extrusion is 60x20 openbuilds and openbuilds wheels.
I didn't have any offset spacers, so just made the bottom holes a tad longer for adjustment (cheapskate . My extrusions were 2x1500 for the X and 1x1000 for the Y - you can make them any size you like. You should be able to see everything in the pix. The only hidden parts are the'skates' underneath, I had to cut a couple of sheet spacers to get the skates to align perfectly. The backplate on the main machine head has a pile of holes - other than the outer 4 and one at the bottom, they're all tapped M4 to accept various 'tools'. The holes are the correct tapping diameter, so if the tap falls through, then it's not to be tapped A cordless drill with tap is your friend
Any queries, just ask, none of it is rocket science

Cheers

Neil

 

[jhitesma]

Michael763 sent me a message that he was able to modify my STL in sketchup: https://www.thingiverse.com/thing:2545595

I LOVE it when I get notifications that my "Things" have been remixed! However when I got home and took a closer look I saw that sketchup kind of mangled the arms when he stretched it out

So...since I really needed to do a stretched version anyway to open up the possibility of using more motors I went in and did one with the spacing increased to 52mm which is what Michael763 said he needs for his motor with the prop saver style flywheel.

I just uploaded it to my thing: https://www.thingiverse.com/thing:2450613 as "cutter_body - New-mount-52.stl"

I solved the issue with the longer distance identified in my post above by changing the angle of the upper arms. As I already mentioned the problem was with the "move face" feature that creates the sides:



What this feature did was take the top face of the sides and angled it up to 45 degrees - which on the original design met the "shoulders" of the back nicely. But with the guide support stretched out this far 45 degrees would put it above the shoulders breaking the geometry so Onshape just skipped the move face feature entirely as it was no longer valid.

I solved this by dropping the angle to 40 degrees which puts it close to where it was before with the support arms just shy of the shoulders.

With that changed it now regenerates the full thing no problem with 52mm between the guide and the back:

Note - I still haven't tested any of these 525 mount setups and am a little worried about the strength of the support arms due to how much material I had to remove to clear the mount holes. I really need to upgrade my machine to 525 specs so I can fully revise a cutter for that...or at least print the new mount so I can test things


Also Talking to Michael I realized I may not have made it clear how to edit an existing design like this in onshape. If you just import the STL you won't be able to edit it since onshape can't edit meshes. Instead you need to open my onshape project as linked earlier in this thread - but included again here for convenience:
https://cad.onshape.com/documents/0...cb551c58564783c02f/e/0282404df574b68957c362e8

Onshape will warn you that it's a view only link and if you're logged in will offer to let you copy it. Once you copy it you can do as you like to your own copy. Be sure to click on the "Manage Versions and History" button:



At the top right corner which will let you see all the different versions I've done in this project (hicwic, 525, low rider...)

 

[TEAJR66]

jhitesma, it was your design where I stole most of my design. One reason for redoing it in Sketchup and hanging the file in the 3D warehouse was the ease of stretching or compacting for different size motors. By selecting a couple faces and moving them the distance that you want form the motor mounting face, the rest of the model accommodates nicely without creating any weird geometry. The only other real change was the addition of the extrusion for the bearing. I did not want to play with washers. The frame also matches up to the universal tool mount that was printed with the MPCNC.

There is an updated frame in the works right now. It has hex shaped recesses on the inside to receive the nuts for the guide bearings. Totally unnecessary, just a little addition to keep from reaching in there with tools. I'll post again if I hang the updated frame on Thingiverse.

These are the faces to select and move along the green axis to adjust for other motors.

 

[jhitesma]

jhitesma, it was your design where I stole most of my design. One reason for redoing it in Sketchup and hanging the file in the 3D warehouse was the ease of stretching or compacting for different size motors. By selecting a couple faces and moving them the distance that you want form the motor mounting face, the rest of the model accommodates nicely without creating any weird geometry. The only other real change was the addition of the extrusion for the bearing. I did not want to play with washers. The frame also matches up to the universal tool mount that was printed with the MPCNC.

Glad to hear it inspired you! I'm personally not a fan of sketchup, it's interface is just really non-intuitive and confusing for me, and it's really not very good at generating STL's. Partly just it's export is fairly "low definition" and uses fewer triangles in the mesh resulting in circles and curves that aren't as nice, but also the internal geometry engine that sketchup uses makes it really easy to accidentally design non-manifold parts which is a no-go for 3D printing.

My first needle cutter I did in openscad so it was fully parametric allowing it to be customizable right on thingiverse. But this new one I wanted to do things that are not possible or very difficult to do in openscad so I went with onshape. It's still a mostly parametric design. I'm a much bigger fan of an engineering approach to CAD with everything being either defined by a measurement or referenced to something that's defined by a measurement. Grabbing things and pushing/pulling them until they "look right" just doesn't sit right with me The steps I outlined about how to adjust my current design sound complex - but that's just because I broke them down into such little bites. It's actually only about a 1-2 minute job even with the adjustment to the sides when the angle goes out of bounds. I can do a video which will make it more obvious how quick and easy it is...but my rambling will probably make it seem longer

There is an updated frame in the works right now. It has hex shaped recesses on the inside to receive the nuts for the guide bearings. Totally unnecessary, just a little addition to keep from reaching in there with tools. I'll post again if I hang the updated frame on Thingiverse.

Looking good! I considered adding nut traps there on mine, but I'm honestly not even using nuts at all so decided not to bother. I left the holes slightly undersized so the screws could self-tap and they seem to be holding themselves just fine.

I do like the built in "washer" on the flywheel as well. I considered doing the same on my flywheel...but wanted to be able to experiment with longer stroke in the other positions. Also, and this is the biggie, I have recesses on both sides of my bolt on flywheel so it has to be printed with support - as a result I print it with the front down so the cleaner face is visible and because removing the supports from the 4 small mounting holes is easier than removing it from the large hole that fits over the "nose" of the motor. If the support doesn't come out of the small holes cleanly it's not big deal to drill them out, but if it doesn't come out of the big pocket then the flywheel won't mount right. So adding a bump like that on mine I'd either have to print it the other way around and worry about removing support from the big pocket which requires higher precision - or print it with a bunch of support under most of the front face and that just seems like a big pain!

Eliminating that washer would be nice though. I learned the hard way that if it's too big bad things happen, and finding an off the shelf washer the right size is impossible at my local hardware stores.

I love seeing all the variants! I really like how you made yours narrower so it fits on the 525 mount better. That's probably what I'll do on my next one when I eventually upgrade my machine to the 525 parts.