Cutting foam sheets... with a needle!

[dkj4linux]

They have seen the needle cutter, but are dedicated to rotary cutting.
The Rascal looks like a good value considering what it is capable of doing. If you only want to cut foam, you can save a couple hundred dollars.

Heli2Go: the needle cutter is an inexpensive and straight-forward build that can be adapted/attached to virtually any CNC machine. This thread is full of examples: from my original wooden BuildYourCNC-based monstrosity, to Joachim's half-ton commercial beast, to Neil's exceptionally clean DepronCNC, countless MPCNC-based CNC machines, and any number of custom-/purpose-built machines...















and the list goes on...

-- David

 

[Hell2Go]

When I get some time, I will read thru the entire thread...
I have built a 3d printer from a kit and that mostly works, I should be able to handle building one of these. I look forward to your guidance as I build mine. I would like to adapt it to a bigger work area and a head unit that's capable of cutting .250 inch polycarbonate parts that are 20x70inch. Anyone done something similar? Might need a rotary cutter or maybe a laser...

Mostly I wanna setup for the pincutter for my planes... thanks guys

 

[rockyboy]

When I get some time, I will read thru the entire thread...
I have built a 3d printer from a kit and that mostly works, I should be able to handle building one of these. I look forward to your guidance as I build mine. I would like to adapt it to a bigger work area and a head unit that's capable of cutting .250 inch polycarbonate parts that are 20x70inch. Anyone done something similar? Might need a rotary cutter or maybe a laser...

Mostly I wanna setup for the pincutter for my planes... thanks guys

Welcome to the fun!

Check out the Lowrider for a frame design (by the same guy that did the MPCNC) that will handle the 70 inch length no problem, and can run a router for plywood and polycarb cutting too.

http://forum.flitetest.com/showthread.php?36066-Lowrider-CNC

 

[ftwingnut]

When i get that far, i am not going to do anything for counter balance. Those motos in tandem are penty strong. I know this from the way there was no stopping it when my shirt got caught in the belt and bearings once. Thank goodness it happened close to the far end of a cut and the gantry quickly went the other direction. Moment of sheer terror.

If standing up does not work, i can always lay it down.

You might want to rethink that strategy. Agreed that the motors are plenty strong enough to probably lift the gantry and any tool you have attached, but what happens when the cut job finishes and the motors are turned off? I can see the gantry crashing to the bottom because it has no counterbalance.

 

[TEAJR66]

You might want to rethink that strategy. Agreed that the motors are plenty strong enough to probably lift the gantry and any tool you have attached, but what happens when the cut job finishes and the motors are turned off? I can see the gantry crashing to the bottom because it has no counterbalance.

If home is lower left, no where to crash to.

 

[ftwingnut]

Well I know I probably said I would keep you all posted during my build, but I tend to get focused on what I'm doing and forget to take pictures and document things. I ended up making a 36" x 48" unit, so my useable space is about 26" x 38" which will work out perfectly for what I will do with it:


I started out with a cheap GRBL controller, which worked ok, but when I was hooking up and dialing in the X and Y limit switches, the controller smoked for some reason. Not sure why, it definitely wasn't a wiring issue on my part. It even took out the Arduino connected to the GRBL. I then replaced it with an Arduino Mega and a RAMPS 1.4 with 4988 drivers running 16th stepping. This set up has been going strong for me.

My first test was with a sharpie marker, and a simple heart shaped sign that read "I love my wife!" She has been very supportive of this project, and is excited about the wood carving and other projects we can do with it. After that successful test, I build the needle cutter, using Jason's frame design on Thingiverse. I opted to wait on the intermediate alignment bearings until I had tested it out, and so far, I have had no issues. I am using an .035 mig tip with .025 wire, and I found an old CPU heat sink in my box of spare parts that I drilled and tapped to hold the mig tip. Everything runs cool as a cucumber in a refrigerator. I ran a simple test cut of a 100mm x 100mm square to make sure my machine measurements were calibrated correctly. After that, I cut that same "I love my wife!" job in foam and gave it to her. After that, I started cutting out the parts I need to make a vacuum plate for holding foam sheets while cutting. Right now I am just using weights, but have to keep moving them around as the cutter moves.

Here is a picture of my cutter head:


And here is a video of my cutter in action, cutting the top sheet for my vacuum table:

I have used Sketchup for years to design 3D printed parts, and to make foamboard airplane designs for printing and cutting. It was a natural step then for me to use Sketchup to design my vacuum table parts, export them as DXF and bring them right into Esltcam. Jason's tutorial video on how to use Estlcam was extremely helpful, and I was able to send the job to the cnc and cut two sheets in about 40 minutes.

I do have a couple questions:

How do I increase my travel speed when moving from cut to cut? I have tried a few different things, but nothing seems to change it, and I don't find that speed setting in the tool config in Estlcam.

How are you guys homing your machines prior to cutting? Particularly the Z axis, but interested in all axes.

Is anyone else using Repetier Host for interfacing with their machine? When I tell Repetier Host to home the X and Y axes, if the gantry is too far from the home position, it will only move a certain amount, and then act like it touched the switch, moving back and forth a small amount, but it is no where near the limit switch. I have to hit the home button a couple times to get the gantry all the way to the home switches. It's as if there is a maximum limit that the motors are allowed to move while looking for home, but I can't find that setting either.



Thanks again to everyone for their inspiration and encouragement. I am loving this machine.

Brian

 

[TEAJR66]

How do I increase my travel speed when moving from cut to cut? I have tried a few different things, but nothing seems to change it, and I don't find that speed setting in the tool config in Estlcam.

How are you guys homing your machines prior to cutting? Particularly the Z axis, but interested in all axes.

Is anyone else using Repetier Host for interfacing with their machine? When I tell Repetier Host to home the X and Y axes, if the gantry is too far from the home position, it will only move a certain amount, and then act like it touched the switch, moving back and forth a small amount, but it is no where near the limit switch. I have to hit the home button a couple times to get the gantry all the way to the home switches. It's as if there is a maximum limit that the motors are allowed to move while looking for home, but I can't find that setting either.



Thanks again to everyone for their inspiration and encouragement. I am loving this machine.

Brian

I have not adjusted the travel speed. I believe there was a discussion about it here on theis thread or in the Viscious1 forum. I think i read that it is set to the feed rate for X and Y. Not sure it can be adjusted, short of modifying the program.

For homing prior to the first cut, i push X and Y to zero. I move Z till the needle meets the foma at the bottom of the stroke.

Lately, Repetier Host has has just been used to view the file after Estlcam. I don't even do it for each cut file anymore. I have not interfaced with the machine throught Repetier since just after i built it. Everything is from an SD card, through the smart controler now.

 

[ironkane]

Since you're using Ramps, you might want to consider using Estlcam to interface with your MPCNC. I forget where I got the instructions, but I'm pretty sure this thread was my starting point. If I recall, it was mostly just installing the drivers on my laptop. Nice thing about using Estlcam is that it remembers where home is as long as you don't manually move anthing. I eyeball home position and set it via the popup controller. Since it's just foamboard, close is good enough unless your cut lines get too close to the edge. "Perfect is the enemy of good".

The feed rate settings are in "Setup\CNC Controller"

I have used Sketchup for years to design 3D printed parts, and to make foamboard airplane designs for printing and cutting. It was a natural step then for me to use Sketchup to design my vacuum table parts, export them as DXF and bring them right into Esltcam. Jason's tutorial video on how to use Estlcam was extremely helpful, and I was able to send the job to the cnc and cut two sheets in about 40 minutes.

I do have a couple questions:

How do I increase my travel speed when moving from cut to cut? I have tried a few different things, but nothing seems to change it, and I don't find that speed setting in the tool config in Estlcam.

How are you guys homing your machines prior to cutting? Particularly the Z axis, but interested in all axes.

Is anyone else using Repetier Host for interfacing with their machine? When I tell Repetier Host to home the X and Y axes, if the gantry is too far from the home position, it will only move a certain amount, and then act like it touched the switch, moving back and forth a small amount, but it is no where near the limit switch. I have to hit the home button a couple times to get the gantry all the way to the home switches. It's as if there is a maximum limit that the motors are allowed to move while looking for home, but I can't find that setting either.



Thanks again to everyone for their inspiration and encouragement. I am loving this machine.

Brian

 

[jhitesma]

The travel speed is set in ESTLCAM's config not in the tool pane. However I don't have ESTLCAM on this computer here at work so I can't check exactly where to change it and what I'm using.

But it is explained on the vicious site:

Full page: https://www.vicious1.com/estlcam-basics/

I think that's the old ESTLCAM 9 still and it's a little different in 10. I don't remember if I'm still using those values or if I got brave and bumped them up a bit. I think I may have bumped up the X/Y since I'm pretty sure I've run it as fast as 3000mm/s but don't remember if I changed to that as default or not.

 

[jhitesma]

As for homing, I follow Ryan/Allted's method of not using endstops.


For Z I move the needle so it's fully extended and then manually adjust the Z so the needle just barely touches. I do this in the middle of my bed since there's about a 1-1.5mm difference across my bed and the middle seems to be the closest to "neutral". I look for the needle to just barely drag against the top of the foam but not quite leave a mark doing so.

Then I move the needle so it's fully retracted and set X/Y.

For X/Y I just position the needle at the lower left corner of my foamboard then reset my RAMPS board to zero it out. I used to use gcode to reset it to 0 but the version of Marlin I'm currently on does funny things when I try that. It works normally at first, then partway through goes crazy when it thinks it's hitting the end of travel even though it's nowhere near.


Getting Z just right took some practice. First few dozen times I found it very frustrating...but once I got the knack for it things got much easier and now I do it without even thinking.

I do suggest redoing Z each sheet since it seems adams has been highly inconsistent in thickness of their foam lately But I try to make sure I use all similarly sized pieces for a project and then don't bother to re-zero Z between sheets.

 

[ftwingnut]

Thanks so much for all the quick answers. I will be working with it tonight after chores, and will see if I can get those things ironed out.

Brian

 

[ftwingnut]

Jason was correct, setting the rapid feed for X and Y in Estlcam did the trick. I started increasing it and running test cuts with the Z axis several inches above the table, and have gotten it up to 4000 so far with no problems, and it definitely cuts down on the job run time. I will continue to increase this until I run into problems and then back it off a bit.

I have cut 3 sheets for my vacuum table so far, and finally broke my needle, right where it bends to wrap around the flywheel bearing. I tried to make a new needle, but continued to run into problems getting the new one to stay on the bearing. I finally printed out Mark's needle holder for an 8mm bearing and put that all together. Now the needle stays on, but the additional mass has introduced some vibration, so I need to rebalance, and the running needle is bowing more than it did without the needle holder. While running it now looks like this () instead of this \/ so I might have to actually add the guide bearings or some guide blocks after all.

 

[jhitesma]

Jason was correct, setting the rapid feed for X and Y in Estlcam did the trick. I started increasing it and running test cuts with the Z axis several inches above the table, and have gotten it up to 4000 so far with no problems, and it definitely cuts down on the job run time. I will continue to increase this until I run into problems and then back it off a bit.

Glad to hear it! I forgot to check last night so I'm still not sure what feedrate I'm actually using there. 3000 was a guess and my memory is horrible for numbers so probably not what I'm actually running I'll try to remember to check...I need to go out there and turn off the AC anyway now that we're finally under 80 for or daily high temps.

I have cut 3 sheets for my vacuum table so far, and finally broke my needle, right where it bends to wrap around the flywheel bearing. I tried to make a new needle, but continued to run into problems getting the new one to stay on the bearing. I finally printed out Mark's needle holder for an 8mm bearing and put that all together. Now the needle stays on, but the additional mass has introduced some vibration, so I need to rebalance, and the running needle is bowing more than it did without the needle holder. While running it now looks like this () instead of this \/ so I might have to actually add the guide bearings or some guide blocks after all.

Bummer about breaking a needle, that is a common spot for them to break if the bend is too sharp. I use round nose needle nose pliers when I make mine to help make sure I don't accidentally create a stress point in the metal. My current needle held on the bearing with a drop of super glue and squirt of kicker has now done around 40 sheets of foam with no problems - other than when I messed up setting my Z and dragged it through the foam bending it. But that was my own fault

Two thoughts on your current situation.

First I wonder if the imbalance is causing the change in bow - might be setting up some kind of resonance. Second I wonder if the needle holder moved the point where the wire starts to flex lower and that's why the bow shape changed. Based on the design of the needle holder that seems likely to me since it constrains the needle for a bit after it comes off the bearing. So instead of the flex starting where the wire bends coming off the bearing it starts to flex where it leaves the needle holder. So I can easily see that causing a change in how it flexes.

 

[ftwingnut]

First I wonder if the imbalance is causing the change in bow - might be setting up some kind of resonance. Second I wonder if the needle holder moved the point where the wire starts to flex lower and that's why the bow shape changed. Based on the design of the needle holder that seems likely to me since it constrains the needle for a bit after it comes off the bearing. So instead of the flex starting where the wire bends coming off the bearing it starts to flex where it leaves the needle holder. So I can easily see that causing a change in how it flexes.

I was wondering those same things last night while I was watching and listening to it. I gently placed my fingers on each side of the wire while it was free running, and started closing the gap to act as a guide. the more I closed it up, the faster the motor spun, so there was obviously some induced drag from the wire bowing outward as well. I think I am going to 3D print a simple guide that will screw into the bearing holes on your design and see how that goes. I just don't have any more bearings, and don't want to have to invest time and money into getting more just for this issue.

I'll let you know how I fare.

 

[moebeast]

My needle holder hasn't completely eliminated the needle breaking for me, but it is easier to replace. They always break at the bottom of the holder, so I think some sort of stress relief might help spread the load and increase the life.

I should add some guides to see if that helps.

I use 4800 for my rapids with no issues.

 

[jhitesma]

I checked over lunch, I'm running 4000 for X/Y on rapis and 480 for Z.

Thought I had bumped it up to match moebeast's from the gcode he shared awhile back...but guess I'm still not hitting my limits

 

[ftwingnut]

Ok guys, I finished building and testing the needle cutter, and then I turned my attention to carving and engraving with my dremel. I am wanting to make some Christmas gifts for family doing this. I bought some new cutters of different types and started doing test cuts. I was surprised how much torque it actually required from the stepper motors to push the dremel through the cuts, and I was only doing 1mm step depth. I had tweaked driver currents and feed speeds in order to get a decent cut, but was discouraged at how slow I needed to go, and how many passes I was going to have to make in order to get an acceptable depth carving.

I had seen others that were using trim routers for their tooling, but was tentative to spend money on one only to have it only work marginally better. I noticed that Harbor Freight had a 1/4" trim router for $29, but didn't really have the extra money at the time. A few days later I helped out a friend, and in return he paid me, which I wasn't expecting. The next day another friend gave me a 25% coupon for Harbor Freight that was going to expire, and he said he wasn't going to use it. I took all this as a sign that I needed to buy the trim router, and I also picked up a package of router bits. When I got home, I immediately found an mpcnc mount for the router and started printing it. The next morning I mounted it up, loaded the same test DXF file I had used for my dremel, and recoded it with the new tool settings. I flipped the power switch and clicked print, and off it went, throwing sawdust everywhere. I was amazed at how much faster I could push this new tool, and how much cooler my drivers were during the cut job. It's only been a few days since then, but I've been carving and engraving all kinds of things in wood and lexan. cutting plastics definitely requires a bit of trochoidal milling to keep it from melting, but it works great and the finish comes out well.

 

[dkj4linux]

Outstanding, Brian. I know Christmas gifts take priority right now... and it looks like you've got it on the run. Great work!

Congrats on getting the needle cutter built and tested as well. I look forward to seeing some the planes you build using it

-- David

 

[jhitesma]

Nothing like strapping it to a CNC machine to realize just how gutless a Dremel really is

I used mine for a few weeks when I first got my machine going...only to wind up burning out the brushes and bearings in my dremel. They really are cheaply made and not at all up for this kind of use

Glad to hear the HF trim router is working well for you!

 

[TEAJR66]

It's official! I bought the Estlcam license.

Turns out I like exporting the DXF from Sketchup and preparing the cut in Estlcam the best.