Cutting foam sheets... with a needle!

[jhitesma]

View attachment 101840
The only thing I'm not happy with is there is some vibration as the gantry gets to the right side of the machine. Ive loosens up all the tension bolts but the vibration is still there. I haven't tried to cut any parts yet so Im not sure if it will be an issue.

Looking great! Makes me want some honey

I printed a cable chain like that one but wasn't happy with how it came out...and saw a few comments from Ryan/Allted advising against mounting anything (including cable chains) directly to the top of the Z. So..I've been happy with my simple shower hooks instead. Not as pretty, but puts no extra load on the Z and is super quick and cheap.

I have some vibrations in a few places on mine as well but have never noticed them in the cut quality. Even doing very small fine detail work with the laser it looks like the gantry is unstable - but the accuracy seems unaffected. I can't figure out why...but I'm not going to complain

 

[moebeast]

trying to build one of these.... Foam Ripper but seem to be missing some things. i printed all the STL files but don't have the side rails that run along the board. are these made from something else? if so, where is the templet? i PM the guy but seeing you have a message on this board is not easy. you have to look, so i assume he just hasn't seen it.

any help guys?

thanks,

jason

Hey Jason,
Sorry I didn't see your pm. For some reason I stopped getting notifications for this thread as well. The parts you are referring to are what I called X-carriage plates. They are too big for my printer, so I cut them from flat stock. The pattern is in the .dxf files. I used my mpcnc to mill them from HDPE, but plywood or mdf will work. I used 3/4" thick plates, but thinner may work as well. These plates can be cut out with a drill and jigsaw. The only hard part would be the stepper motor pocket.

Let me know if you are still stuck. mrmoebes@gmail.com

Mark

 

[EDinCT]

IT WORKS!!!! (sort of.)

I spent the day doing some final wiring and decided I couldn't go to bed without trying this puppy out. I spent some time using Inkscape and Estlecam to prep an FT Cruiser. I did a dry run without the needle spinning and the Z lifted way up just to verify that I actually laid out the parts such that I wouldn't crash my machine. All seemed good so I loaded up some foam and let her rip. WOW! This thing is amazing. Cuts are very clean.
Just one problem... I'm breaking needles. About half way through the first sheet of foam and the needle broke right in the middle- in a spot where there are no bends. I replaced it and reset back at the origin and started over... not starting the needle until it got to the part where it broke. it ran great again for about the same amount of time and broke again. I decided to stop and post a short video. Maybe one of you guys will see something obvious I am doing wrong.
-Needle is sharp, .025 dia.
-running 9mm/sec, RPM unknown (about "half throttle" on a 920kv motor on 12v.)
- Just after the break the needle guide is cool to the touch.
- wire was straight with no bends except right at the top by the bearing, but thats not where it is breaking.

Very clean cuts. Not jagged at all.


Here is where the breaks seem to happen.

 

[EDinCT]

This morning I went back to Estlcam and changed my feed rate to 6mm/sec, slowed down the rpm of the needle and tried again. Looks like that may have done the trick. It ran for almost 18 minutes just to do two spars, but the needle didn’t break. The guide was much warmer this time but not so hot that you can’t hold it.
I’m really impressed with how much better these parts fit over the laser cut or hand cut. This really is the ticket for cutting foam!! Yeah sure it cost me almost $400, but just the fun of building the MPCNC made it all worth while!

 

[dkj4linux]

Spectacular build... and first cuts! Great work! -- David

 

[EDinCT]

Spectacular build... and first cuts! Great work! -- David

Thanks!

47 minutes to cut this out- a little slow but no broken needles. Needle guide is pretty hot after al that, but still not that bad. I am super happy with this thing. Thanks again to all who did the leg work before me to get all the kinks worked out!

 

[jhitesma]

Too high of RPM was what caused my needle breakage issues. Once I got an IR tach ($13 on banggood or amazon) I realized just how much faster I was running it than I thought I was and slowed down - don't think I've broken a needle since.

Though...once I upgraded to the guide bearings and longer needle I upped my RPM a bit more and and it seems happier there now. Still not running as fast as I was when I was breaking needles regularly - but lets met do faster feed rates and keep everything happy. You'll probably be able to double your feed rates (maybe a bit more even) once you get everything dialed in. Though...I spent a couple of months cutting slow because I was so happy just to have it working once I solved my needle breaking issues

I found calculating the RPM is tricky since ESC's aren't very linear. So 50% throttle isn't necessarially 50% of the calculated max RPM given your voltage and KV. That was what caught me and had me going crazy with breaking needles. The math told me I wouldn't be running nearly as fast as I actually was due to the throttle curve in the ESC.

 

[ironkane]

I've had very good luck with needles. The last one that I broke was when I was getting everything dialed in.

I don't remember if this was mentioned in this 189 page thread: Annealing your needle? Throw your finished needle onto a baking sheet @ 500 degrees for 30 minutes and then turn off the oven and let it cool naturally.
Also try not to put any nicks or even deep scratches in the needle. They will be the snapping location.

I have no idea what RPM I was running. I shoot for as smooth sounding as I can push it without dipping into "are you crazy?" speed where the is sounds like it's going to shake itself apart.

 

[ironkane]

Progress on a Z gantry for my OpenBuilds Acro mod. Waiting on some stuff I forgot to order like the 8mm acme nut block, some standoffs and some screws. The acrylic back plate is replacing one of the plates in the Acro kit. The 2020 extrusions were leftovers from resizing down from 40 x 40 to 40 x 30. Gantry plate and wheel kits from OpenBuilds. Amazon for the short body Nema 17 and 8mm acme screw.

 

[mrjdstewart]

ok. still trying to print dxl files for the side plates. i have someone who can open the files, put into pdf and print, but he needs to know the scale.

i have the 60" wheels and he says when imported into pdf he needs to, "know what 1 is?"

is it 1 inch, 1mm, 1 pix, 1 ......

thanks,

jason

 

[moebeast]

ok. still trying to print dxl files for the side plates. i have someone who can open the files, put into pdf and print, but he needs to know the scale.

i have the 60" wheels and he says when imported into pdf he needs to, "know what 1 is?"

is it 1 inch, 1mm, 1 pix, 1 ......

thanks,

jason

I think it is 1 mm, but it was a while ago. I will try to upload a pdf version if I get a chance. I am working 4 on, 1 off 12 hr nightshifts, so not much time to tinker.

 

[moebeast]

I think it is 1 mm, but it was a while ago. I will try to upload a pdf version if I get a chance. I am working 4 on, 1 off 12 hr nightshifts, so not much time to tinker.

I added a 1:1 pdf drawing to the Thingiverse files. https://www.thingiverse.com/thing:2520214

 

[Tryb]

Progress on a Z gantry for my OpenBuilds Acro mod. Waiting on some stuff I forgot to order like the 8mm acme nut block, some standoffs and some screws. The acrylic back plate is replacing one of the plates in the Acro kit. The 2020 extrusions were leftovers from resizing down from 40 x 40 to 40 x 30. Gantry plate and wheel kits from OpenBuilds. Amazon for the short body Nema 17 and 8mm acme screw.

How's that machine treating you? I'm eager for an update and to see how it works!

 

[thompsbp]

So I have printed all my parts. Saving up to buy the electronics from Vicious. How hard is this to build? How do you keep it square? How do you keep the tool head at the same z distance from the bed all over?

 

[enola_yay]

Hi everyone,

New to needle cutting foam, just discovered this thread -- could someone kindly guide me to the latest info regarding the needle cutter? e.g. which electronics/equipment to purchase, and the latest file I need to 3D print.

Thank you!

 

[TEAJR66]

This is a good place to start. https://www.v1engineering.com/

 

[enola_yay]

This is a good place to start. https://www.v1engineering.com/

I have already made my MPCNC. Just unsure about the needle cutting mechanism.

 

[ironkane]

Hi everyone,

New to needle cutting foam, just discovered this thread -- could someone kindly guide me to the latest info regarding the needle cutter? e.g. which electronics/equipment to purchase, and the latest file I need to 3D print.

Thank you!

You've found it. I'm afraid you'll have to read the almost 200 pages of this thread. Designing a needle cutter tool head is pretty straight forward. Mount a brushless motor over a Harbor Freight Welding tip with some spring wire fashioned as a needle that's on an elliptical attachment to the motor. People have shared their designs here. Specific questions will be answered fairly quickly, but it's all been covered.

 

[jhitesma]

We really don't have a very good concise source for the latest needle cutter info. I've thought about registering a domain and setting up a little info site to consolidate it...but...seems like every time things seem to be stable someone else comes up with a new idea to improve it

I'm really happy with my latest design:
https://www.thingiverse.com/thing:2450613

In fact it's been so reliable and consistent that I really haven't had to do anything since I started using it in July. My biggest problem has been catching up on finishing and crashing^h^h^h^h^h^h^h^h flying all the planes I've cut with it

It doesn't affect me personally...but the one downside of my latest cutter is it isn't as flexible for different motors and really is designed specifically around the motor I had on hand. Though I have made some modified versions to fit different motors when people have asked and TEAJR66 did one based on mine but designed for a motor he had on hand: https://www.thingiverse.com/thing:2544466

A lot of people have been happy with mobeast's needle holder seems like a nice upgrade...but I'm happy with mine as it is until I need to replace the needle...when that day comes I'll probably try his needle holder as bending the needle and getting it secure on the bearing without creating a weakness in it is one of the trickiest parts of a build.

Overall though the latest info seems to be:

Taller is better - don't get crazy but more height means less bend on the needle so you get longer life and lower friction.
Pre-guides help - Even just some simple wooden wedges like David used: https://www.thingiverse.com/thing:1211039 or some bearings if you have some on hadn and like that nice swish swish sound they make
An oiler (just some cotton ball soaked in light machine oil) can help cut down on friction but isn't generally necessary if you have a tall enough cutter and pre-guides.

Inflation needles work...for a needle guide...but wear out rather quickly and can loosen up causing inaccuracy. MIG tips seem much better - but need to be properly sized to match your needle and work best with a longer needle and pre-guides (and/or oiler).

I made a little calculator to help figure optimal motor RPM for your feedrate: https://jscalc.io/source/46UNa6KQoeqDptKR but in general about 6-7k is a good place to start and 10-15mm/sec is a good feed rate range. Start slower and work your way up.

I strongly suggest picking up a $13 IR Tach from Amazon or banggood. Well worth having. ESC's are linear so trying to set your RPM by calculating a throttle position isn't very reliable. I spent months dealing with flying needles because of that before finally getting a tach and realizing that I was running it way faster than I thought I was.

 

[dkj4linux]

Enola_yay,

I wish I had a simple answer for you about which needle cutter to print but "ironkane" pretty well sums it up. The needle cutter is a relatively simple and flexible device but needs to be adapted to your particular machine requirements (primarily the mount tool mount)... and only you know that at this point. I will go further, however, and say read/skim the last 50 pages of this thread (vs the entire thread) and you'll probably find something you can work with... the most current information will be found in these latter pages.

Of prime importance will be to look at one of the later versions that employs a "preguide"- setup that will convert the needle's motion to straight-line, up/down, motion before it enters the main needle guide (welding tip, inflation needle, custom, etc.). This can be an array of bearings, side-boards, a wooden stack, etc and may or may not incorporate a cotton-ball oiler to help reduce friction and heating in the main guide.

I'd suggest looking at Jason's ("jhitesma") needle cutter body(s)... he's adapted the needle cutter to more machines and mounts than anybody else. Take a look at

https://www.thingiverse.com/thing:2450613

and see if that floats your boat. Please chime in here, Jason, if you are following along.

I started developing a wooden stack pre-guide setup/approach in the following post... though I now think a graduated upper-guide approach isn't desirable/necessary (a simpler 1mm upper-guide stack seems to work best)...

http://forum.flitetest.com/showthre...with-a-needle!&p=360136&viewfull=1#post360136

but I can't really tout it as better, or even "as good" as the other approaches, because I simply haven't used it to cut the amount of foam that Jason, Mark ("moebeast"), or others here, have cut. My attraction to this approach, however, is that it uses the "original" (though taller), printed, needle cutter body... without any special support structure for the pre-guide setup. It also probably requires use of a laser engraver/cutter to pull off... and I recognize many/most folks may not have one of those yet.

Please provide some information about your MPCNC and the tool mount you've used and I'm sure somebody here will be able to get you going on your needle cutter.

Welcome to the party!

-- David

PS: I see Jason has already chimed in... thanks, Jason!