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Cutting foam sheets... with a needle!

mrjdstewart

Legendary member
once again, it has been so long i don't know. i assume so. i have all the original .stl files somewhere, will have to dig deep though.

i'm just kinda crossing fingers at this point. i have the supply list and will check it against, see where we are.

laters,

me :cool:
 
Modifying the new "Multi-cut" by @CapnBry to work with my mpcnc. Looks like it's a simple modification to the commands used to specify what you want the Z-axis to do. Instead of 'M3 S0', I'll be using something like G00 Z5.0000 F540, or something like that, depending on my tool heights.. etc.
Will be performing a side by side comparison later this week (hopefully) between Estcam and just using Mutlicut. Waiting on belts to arrive from V1Eng. Should be here tomorrow. basics tests, and then starting cutting. have like 20 sheets to burn through. :) and plenty of hotglue. need to get my power packs on order as well.

Both of these solutions (Multicut and Estlcam) require some level of intervention for them to work seemlessly. One thing I did notice, as Estlcam makes a much more streamlined cut order for each part, since inkscape separates each line into separate objects, such as lines, curves, poly-shapes, that just means a seperate g-code command for each of those 'objects-to-path'. Will be testing using groups, to see if that improves the necessary cuts on a per part basis. would like to group them up and make sure that it does all a single part first, but not sure it's possible when 'multicut' parses the lines/objects. Not getting my hopes up on that. After all, this would be pretty automated anyway you look at it no matter which work-flow used. - Print, Tape, cut out, spray glue to DTFB, cut foam >>> changes to >>> Import into Inkscape, > ensure proper color assignment , export g-code, automatically cut.
 
Hi, what feedrate and rpm do you guys use when needle cutting? I have had some decent results with 600mm/min and approx 4000-5000 rpm but I wonder if someone has had success with a higher feedrate?
 
Hi, what feedrate and rpm do you guys use when needle cutting? I have had some decent results with 600mm/min and approx 4000-5000 rpm but I wonder if someone has had success with a higher feedrate?

Speeds

The important number to remember is that you need 10-15 strokes/mm to cut cleanly and limit the load on the needle, i.e. feedrate (mm/min) of ONE-TENTH the cutter speed. At 8000-10000 rpm you can use a feed rate of 600-1000 mm/min to cleanly cut DollarTree foam board (paper on), blue-cor fanfold foam, etc. in about 20 minutes. At higher speeds, the MIG tip may heat up and melt the plastic mount, and the bending load on the needle can break it at the top. If your flywheel is poorly balanced and needs to run at lower speed, reduce the feedrate accordingly.

Jason is at 15mm/sec with an rpm around 8500 i think. I will be using this as well.
The paragraph above is from David, and is what he's been recommending all along.

Always good to have a starting point, and increase it from there.
 

TEAJR66

Flite is good
Mentor
Just as i was cutting poster board, contemplating the long life of my current needle cutter configuration, i ran the needle right into the table top. First time in a long time that i threw a needle and bearing. I have not done that since the second or third day after finishing my MPCNC.

Double check those starting and cutting depths.

I was cutting poster board. My spoil board is a single sheet of DTFB (~5mm). I had my needle cutter set for cut through (5.5mm).
 
Just as i was cutting poster board, contemplating the long life of my current needle cutter configuration, i ran the needle right into the table top. First time in a long time that i threw a needle and bearing. I have not done that since the second or third day after finishing my MPCNC.

Double check those starting and cutting depths.

I was cutting poster board. My spoil board is a single sheet of DTFB (~5mm). I had my needle cutter set for cut through (5.5mm).
Just got my mpcnc up and running this week.. did a 75% goblin, and broke a needle right in the middle of my first print ever. luckily, when the needle broke, it happen to be in a 'rapid' move , and I was able to pull the plug, hence, saving, the dtfb, and was able to determine exactly where to restart the cut..

Overall, a 'Successful failure', but need to come up with a better bearing, retention, and needle setup.

What is the preferred needle cutter setup for the MPCNC at this time?
 
Well, so I followed the needle attachment method above, instead of using the retention clip, I just wrapped it around bearing as described in the video. Outcome, lasted 1 sheet cut worth of the horizontal sheet for the foam vacuum table by moebeast. Made it through that sheet. Get all prepped for the 'vertical sheet', turned on cutter, pressed start on the Repetier software.. made it through 1 vertical run trough, and then the cutter disintegrated .. again..grr
1 of the 8 bearings down on the guide was obliterated .

So I did some digging and looked at ERC's flywheel. Quite honestly, there was allot of effort to 'balance' the flywheel part, and in the end result in the video, it was attached using hotglue to the motor. That can't be balanced. or is it? What's the point of putting in all those little specialized washers if you're going to just attach it with a bunch of hotglue? I dont' know.. It may work, but I didn't want to go down that path without 'knowing' the forum has had success with that setup... Anybody using that setup that can speak to it? longevity?

I've been using the flywheel i think @dkj4linux put out on thingiverse, but I think the way I used the holes, it has a 21mm throw on it , so my setup maybe swinging back and for into the bearings causing this excessive wear and heat build-up.

Going to reprint several of these. waiting on parts to arrive from boltdepot for nuts and bolts and amazon for more bearings.

Hopefully I can come up with a reliable solution. trial and error..
 
:D So I went an literally reinvented the 'wheel', and came up with a much much easier flywheel assembly , using the standard bearings, and a cross between @dkj4linux and @Edwardchew flywheels. Using a simple Z-bend with a linkage stopper. No more curving a piano wire that never wants to bend and stay where you want it. And if you want, you can use a standard 'push-rod' from FliteTest with the right mig tip.

Introducing the EZ-Flywheel

Full documentation coming soon ... Update - https://www.thingiverse.com/thing:4685504
Photo Dec 13, 10 08 32.jpg
Photo Dec 13, 10 08 36.jpg
Photo Dec 13, 10 08 40.jpg
 
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:D So I went an literally reinvented the 'wheel', and came up with a much much easier flywheel assembly , using the standard bearings, and a cross between @dkj4linux and @Edwardchew flywheels. Using a simple Z-bend with a linkage stopper. No more curving a piano wire that never wants to bend and stay where you want it. And if you want, you can use a standard 'push-rod' from FliteTest with the right mig tip.

Introducing the EZ-Flywheel

Full documentation coming soon ... View attachment 186131 View attachment 186132 View attachment 186133
waiting for updates. looks great. my guess is though that the linkage stopper will fail from having to completely rotate every revolution.
 
:D So I went an literally reinvented the 'wheel', and came up with a much much easier flywheel assembly , using the standard bearings, and a cross between @dkj4linux and @Edwardchew flywheels. Using a simple Z-bend with a linkage stopper. No more curving a piano wire that never wants to bend and stay where you want it. And if you want, you can use a standard 'push-rod' from FliteTest with the right mig tip.

Introducing the EZ-Fly

Full documentation coming soon ... View attachment 186131 View attachment 186132 View attachment 186133
I like your take on the needle attachment. I am looking forward to seeing your results of continued testing and expanded information. I try to make sure that my needle only extends 8-10mm below the mig tip.
 
I like your take on the needle attachment. I am looking forward to seeing your results of continued testing and expanded information. I try to make sure that my needle only extends 8-10mm below the mig tip.
Agreed.. 8-10mm.. These were the initials photos. when I was going through it.. forgot to cut it shorter.. took it back off and shortened. when in full up-stroke, i have it only 1mm below tip now. Much straighter cuts of course. :)
 

2jujube7

Well-known member
I am considering making one of these, what all would I need to get into this sort of thing?
I'm currently making MoeBeast's Foam Ripper. For me, the total cost is around $91, but I already had a bunch of the stuff. I did lots of research and I'm pretty sure that I found the best deals for most of the stuff that balance cost and quality/reviews. Total cost that I found (minus the table) is around $250 (everything from Amazon and it's glorious 2 day shipping). Here's a link to a spreadsheet of the collection of parts that I found at good prices. Here's the link to the FT article by MoeBeast describing the build. Good luck!