Cutting foam sheets... with a needle!

[bperc]

The only time I've had any fusing of the foam (either to itself or to the spoilboard) was when I had a longer needle and/or too high of an RPM. With either of those I did experience it...and with both oh boy did I have some fusing

I used your needlecutter design for the first time today. What an improvement over the one I was using. 4 bearings guiding the needle makes a big difference. It runs much quieter too. Thank you for sharing it jhitesma!

 

[jhitesma]

Glad to hear it's working well for you! I do like the four bearing design but can't claim credit for the idea - I'm not sure who first tried using bearings for the guide...looking back around pages 45-50 it looks like David or Basscor may have done it first...and then Verris stepped up to 4 bearings (though I think Basscor may have done 4 first) and then Verris went kind of nutty with his 6 or 8 bearing beast

I just happened to be ready for a new cutter shortly after they did all the ground work and was looking for a project to teach myself some new stuff in Onshape Still love seeing a new print of my design in the wild though!

 

[TheSFReader]

Just a small question : couldn't find it (doh), but what size are those bearings ? I'd like to buy some for a cutter.

 

[TEAJR66]

Just a small question : couldn't find it (doh), but what size are those bearings ? I'd like to buy some for a cutter.

3x8x4.
These are the bearings I used.

 

[jhitesma]

If you fly mini quads you may have the right size bearings in your junk bin. They're the size used in 2204 (and 2205 and a number of other common sized) motors. I had a bunch of motors with damaged bells or shafts or magnets that weren't flyable anymore...but still had good bearings. So that's where I got all of mine

 

[TheSFReader]

Ah, I fly some quads, but have yet to trash them enough to have spares/unjunked bearings. Ordered a few now.

 

[ironkane]

CNC up and running! Been mostly playing with the laser. But I did switch over to the needle cutter a couple of days ago. The first video shows my long needle. It protrudes about .8" from the Mig tip. It ran very well despite my cuts were set too deep which caused a lot of heat transference between DTFB and paper-stripped DTFB waste board resulting in a lot of fusing. It did cut very cleanly.

The 2nd video was after I had shortened my needle by .4" and it didn't cut as clean. WTF? Plus my needle now retracts into the Mig tip so that now anything that adheres to the portion of the needle that penetrates into the foam is now able to enter into the tip for potential accumulation and clogging. Look how rough looking the cuts are getting about halfway through the video.

So I'm going to make a new needle when I get a chance and run a side by side comparison where the only change is the needle length. I think my original needle of .8" is probably going to be the ideal length or possibly .75".

Long needle

Shortened needle

Lasers are just cool

Note how blissfully quiet the CNC is without running the vacuum table. This CNC rolls as smooth as butter. Good bye electrical conduit!

 

[dkj4linux]

Lasers are indeed fun. For grins, replicated small cross-stitch pattern for daughter... jumbo craft stick. Banggood 3.5 watt laser, 100 mm/min, single pass, Octoprint timelapse. Pattern is 26mm square with 14x14 array of 1.2mm holes... just under 10 minutes per pattern. Used Onshape to create dxf (and stl for printed version... needs tweaking), imported to Inkscape with JTech laser plugin for gcode creation.

 

[dkj4linux]

Posted to my other MPCNC-inspired CoreXY laser engraver thread... a reworked X carriage and Z-axis actuator.

Just thought it interesting to see our own Jason (jhitesma) has been playing with the little, very cheap, 28BYJ-48 stepper motor to build a automated fish feeder... https://www.thingiverse.com/thing:2959685. Coincidently, I've been playing with the same motor, converted to bipolar, used in a linear BB-bearing stepper slide I found out on Thingiverse (https://www.thingiverse.com/thing:2813896).

 

[jhitesma]

Yeah I've had a couple of those motors laying around since I used 2 to make a little robot for my daughter about 9 months back. Been trying to find a use for them since. The fish feeder seemed like a perfect use - but those little things are so weak it's proven trickier than I expected.

Finally seems to be working now though. Hoping to write up an instructable on it tonight to enter into the Pets and Make it move contests

I do like those little motors...but they're tricky to use due to their slow speed and low torque. I just modified one to turn it into a bipolar stepper but haven't had a chance to wire it up and try it yet.

Rather impressed that yours is able to move that fast and lift that much weight. Guess I should get that modified one wired up!

 

[dkj4linux]

Yeah I've had a couple of those motors laying around since I used 2 to make a little robot for my daughter about 9 months back. Been trying to find a use for them since. The fish feeder seemed like a perfect use - but those little things are so weak it's proven trickier than I expected.

Finally seems to be working now though. Hoping to write up an instructable on it tonight to enter into the Pets and Make it move contests

I do like those little motors...but they're tricky to use due to their slow speed and low torque. I just modified one to turn it into a bipolar stepper but haven't had a chance to wire it up and try it yet.

Rather impressed that yours is able to move that fast and lift that much weight. Guess I should get that modified one wired up!

Hey, Jason! Good to hear from you.

That bipolar hack is a simple mod and just what that little motor needs... probably your fish feeder would benefit as well. If you haven't already, check out the videos from the Thingiverse page for the linear slider... https://www.thingiverse.com/thing:2813896. It's capable of far more torque than unipolar and can be driven from a Ramps with A4988 or DRV8825 drivers, if you're setting it up for CNC use. Take off all the microstepping jumpers and turn down the Vrefs... it can only handle 150ma or so. Then you can go into Marlin and set the steps per mm to a value that moves it the distance required. Seems like it should work quite nicely as a light-weight Z-axis for my MPCoreXY laser engraver. Kudos to John Mulac (3DPRINTINGWORLD) for the linear actuator... and he has a bunch of other interesting "things" out on TV as well.

For your fish feeder, you can probably just replace the little Darlington driver chip with one of the A4988 drivers and control it with step and direction signals from your Arduino. That what I did for that MPCamSlider project... no Ramps, just a couple of the drivers on a breadboard, coupled to an Arduino Uno. I'm sure you can handle the alteration to your sketch easily.

Again, great to hear from you. -- David

PS: Pardon the loud TV in the background... forgot to mute again

 

[TheSFReader]

I've got a few of them too, and would like to use them. Unfortunately, apart from torque/speed issues, they also lack on precision : quite a lot of backlash for example. But will try them in bipolar configuration...

 

[dkj4linux]

Just a FYI...

I rounded up most of the parts needed to build the MPCNC-inspired CoreXY laser engraver that is the subject of my other thread (https://forum.flitetest.com/index.php?threads/mpcnc-inspired-corexy-laser-engraver.35285/) and uploaded it to Thingiverse

https://www.thingiverse.com/thing:2375050

I think there's a spacer missing yet and it's possible that a part or two may need reorienting to print properly but most of the parts are there. I've included pictures that show the assemblies... it's actually IMHO simpler (not better!) than a MPCNC; i.e. fewer motors, belts and less wiring. The videos are showing the original configuration but operation hasn't changed. I actually download current firmware from the MPCNC website and changed only a few lines in the configuration.h file to get CoreXY operation and proper steps per mm on each axis.

The linear Z-axis linear slide assembly is found at https://www.thingiverse.com/thing:2813896... thanks to John Mulac (3DPRINTINGWORLD) for a really nifty mechanism!

-- David

 

[jhitesma]

Hey, Jason! Good to hear from you.

Good to see you active and posting again too

For your fish feeder, you can probably just replace the little Darlington driver chip with one of the A4988 drivers and control it with step and direction signals from your Arduino. That what I did for that MPCamSlider project... no Ramps, just a couple of the drivers on a breadboard, coupled to an Arduino Uno. I'm sure you can handle the alteration to your sketch easily.

Well, I've got the fish feeder working pretty well (even at 5v, though even better at 9v) now even without the bipolar mod. But I did modify one motor to play with. Just have to clear space on a breadboard to play with it still.

Right now the big issue I'm having is finishing up the code. I've used the accelstepper library before but had forgotten most of it already. Finally got it figured out - but kept having phantom food dispenses happening. Finally track that down though - forgot I had left the code to read a button enabled and the pin was floating. Tied it to ground until I can be bothered to wire in a button and pull down resistor and finally solved those.

But...I'm not getting it to dispense on a schedule yet. I don't have any RTC's (Real Time Clock for those playing along and lost by the acronym) on hand so it's just counting ticks and estimating time based on that. But something is off because even if I set it to go every couple of minutes it never triggers. So still need to look at that a bit closer...and since I leave for Ohio this Thursday I may just have to bite the bullet and get someone to feed the fish while I'm gone Then again I do have a digispark Oak on hand which has wifi built in that works with the particle cloud so I could make an "internet of things" fish feeder which just uses nntp to check the time....but I can't bring myself to trust my network would stay up while I'm gone. Plus since I finally found the trick to getting the stepper to completely shut down between moves the power consumption on this thing should be low enough I can probably run it off a small battery for a week or so.

 

[Rit]

Ok, So, what is the best needle cutter set up and parts list?

 

[dkj4linx]

Ok, So, what is the best needle cutter set up and parts list?

Whatcha got in way of cnc... tool mount, intended use?
Totally diy... use materials you are comfortable working with - wood, metal, 3dprinted plastic.

 

[dkj4linx]

Silly phone... not logged in right. -- David

 

[Rit]

I will design my own setup for my printer, but I need to know wire size, Mig tip size, motor, bearings, and so on.
Thanks.

 

[dkj4linux]

Smartphones and old people are a bad combination. I'm home now so hopefully will make more sense...

Rit, it's been a while but I've used 0.025" piano-/music-wire and a 0.035" MIG tip without issue in the past. Using a smaller diameter MIG tip would probably work just fine... a little less slop needle-in-guide but probably a bit more friction. I strongly suggest using a "pre-guide" setup (bearings, sideboards, etc) that constrains the motion of the needle to near-straight-line motion *before* the needle enters the guide. Jason (jhitesma) has a very popular 3d-printed design that you may use or adapt to your situation. Check it out... https://www.thingiverse.com/thing:2450613.

I'm not sure exactly what motor Jason's cutter is designed for but I'm pretty sure it is in the 1000kv range. If you are not 3d-printing, but using wood/metal/etc and constructing it yourself, feel free to use whatever you have on hand that's reasonably close. That's how I started and this thread is full of examples of successful cutters that people have made using RC motors, ESC's, servo testers, and materials they already had on hand. Bearings can often be salvaged from junker RC motors and the like -- 8mmX4mmX3mm is a size often found/used -- but suitable bearings can be found on Ebay, etc.

Let us know more about what your "printer" looks like and how you plan to build and use your needle cutter. We'd love to help. -- David

 

[Rit]

Good, I ordered bearings, .025 wire, and .035 tips, I have an Eflight 2210 1450KV out runner and ESC. I will be 3d printing the mount to fit my custom Cartesian 3D printer with Duet WiFi elect5ronics. I have a few stepper motor heatsinks that I will use on the Mig Tip. I currently am setting up an old Jtec 2.8W laser on it.
The printer as I I said is a custom Cartesian printer that uses 1/2" EMT conduit for the frame, and smooth rods for the axis, I designed it to have 4 park-able hotends, which currently only 2 are being used, which are E3d-Aero Titan extrudes, and the other 2 will probably eventually be E3d Cyclops.
But, I can't wait to get this njeedle cutter going, Kudos to whomever figured it out and made it public, I will now be able to download foamies.