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ERC TimSav - Cheap DIY CNC Foamboard Cutter

The source files are on Thingiverse and it is likely you'll need to tweak some of the sizes to make it fit just right on your printer, but here is the spinner I have on my TimSav right now.

thanks a lot for the stl !
today i constructed my own flywheel, based on your idea, but i have 2 bearings to guide the screw which holds the standoff. it was balanced properly and worked well in the beginning, but whatever i try, the assembly gets hot and melts after a while...no matter, if i use original or tweaked flywheel...maybe i should buy new bearings and washers.

update: i replaced the bearing with a bearing of my 450 size helicopter. it has the same dimensions, but is 2.5mm thick; better for mounting the wire. had it running for 10 minutes and it remained absolutely cool...so the bearings were defect.
 
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CapnBry

Elite member
Finally got my motor and got rid of all that extra wiring that came from using my other motor and nice ESC. Now using an old 12A EMAX from an Power Pack A. I think it looks so pretty that I even took it outside for a stroll.

DSC07040.JPG

DSC07044.JPG


The motor has a 3mm long shaft so the screw I was using to attach it to the motor shaft caused it to tilt as it wasn't fully engaged on the motor shaft. Luckily, there are M3 bolt holes in the top so I redesigned again and now the grub screw is the counterweight. I had to increase the stroke to 8mm to have space for the mounting bolt heads but it runs even quieter than before with 2x washers on the grub-terweight.

The needle is already chewing through the 3D printer nozzle though. I guess it is pretty thin brass there at the tip so at some point down the road I'll probably need to get a welding tip. The bottom-right wheel on the needle's mountplate was a teensy bit loose so I just wrapped a couple wraps of PTFE tape around it. Testing has gone well though and I just need to make a new homing plate to account for the new needle/motor geometry. I did pretty good at just using spare parts to build this:
  • OpenBuilds V-Slot 2040x1m and 2020x1m - $35.01 shipped
  • 2212 930KV brushless motor - $9 shipped from eBay WHAT
  • CNC Shield - $9 shipped
  • $53 out of pocket and only about 100 hours of 3D design and problem-solving
First thing I think I am going to cut is an FT Sparrow and make a 3 channel glider out of it. I have nowhere to fly so I might enjoy building a launching mechanism and gliding around the cul-de-sac. Maybe even FPV if I want to throw up on launch!
 
I've got a silly question for you....
Edward's original design has the needle being guided into the welding tip with bearings, so I'm assuming the needle tip will be going straight up and down. You're not doing that. Your needle is essentially rocking side to side because of the flywheel. Does your tip have a long enough constriction to keep the needle straight, or does the tip of the needle move slightly side to side? You mentioned the needle chewing through your nozzle. Maybe adding the bearings would eliminate that? I'm assuming the bearings would cause the needle to flex with each rotation though. What's the life of a needle with Edward's design?
 

CapnBry

Elite member
I've got a silly question for you....
Edward's original design has the needle being guided into the welding tip with bearings, so I'm assuming the needle tip will be going straight up and down. You're not doing that.
Right but a big difference is that the welding nozzle is constrained across its entire length and a 3D printer nozzle is really only constrained right by the tip. Therefore it just pivots at the nozzle tip and the side to side movement is proportional to the stroke vs the motor distance. My motor distance is 65mm and my stroke is 8mm so a 8/2 / 65mm triangle forms a 3.52 degree angle at maximum left or right deflection. At that point the needle is 4mm long in the diagonal so X / 4mm = sin(3.52) or a 0.245mm left/right to center deflection or about 0.5mm of wobble per spin. You're right that having it vertical by passing through some bearings would reduce that at the cost of bending the needle back and forth every stroke. I was hoping to get away without straightener bearings (because I don't have any) but it would definitely improve the performance if the needle went straight.

I think it would still chew through the 3D printer nozzle though, because there's a lot of sideways force on the needle as it cuts, or rather enough sideways force that it will push against the nozzle egress regardless of how it enters the nozzle. The material there is just too thin to hold up (2mm vertical). It cuts pretty OK but the bottom cut is a rougher than I'd like. I'd probably try using a couple grooved 8mm ID bearings I have on hand with a welding nozzle cut down (length reduced) next but probably not for a month.
 
I'd be interested to hear how it turns out.
I'm hoping to get a 3D printer when my tax money comes back. Until then, I'm just gathering ideas and I enjoy seeing your experiments.
 

CapnBry

Elite member
I've posted STLs all the parts for my carriage to Thingiverse. I've cut a couple sheets with it so far and it works, but I'm having a real hard time with the depth of cut, due to the foam board being domed no matter how much tape I try to put on it. Other than the vacuum table idea, has anyone tried any alternative ways to keep the workpiece flat? I was thinking of making a caster wheel or some sort of big steel ball under the carriage that pushes down on the DTFB as it drives around.
 
I've posted STLs all the parts for my carriage to Thingiverse. I've cut a couple sheets with it so far and it works, but I'm having a real hard time with the depth of cut, due to the foam board being domed no matter how much tape I try to put on it. Other than the vacuum table idea, has anyone tried any alternative ways to keep the workpiece flat? I was thinking of making a caster wheel or some sort of big steel ball under the carriage that pushes down on the DTFB as it drives around.
The domed side should go down so that when you tape/pin/hold the sheet down to the spoil board the board should be flat.
 
I finally pulled the plug and ordered a 3D printer, an ERC TimSav LITE KIT, and the v slot rails I'll need.

I've never messed with 3D printing, so I first have to learn that before I can put my foam cutter together.
 

CapnBry

Elite member
I was in the process of making some plans and ended up with a Full Cut SVG, a Score Cut SVG, and was starting a new SVG for labeling the parts and putting reference lines and I said what the heck am I doing here this is a mess. In the spirit of "Do not spend an hour doing something you can spend 100 hours automating" I present MULTICUT:
inkscale-extension-multicut.png


This updated extension allows you to just have one freakin' drawing and have all of them in the same file. It uses the path stroke color to determine what type of cut it is.
  • BLACK - Full cut
  • RED - Score cut
  • BLUE - Blue cut
  • GREEN - Green cut
The last two I didn't name "reference" or "guides" or whatever because you can just use them for whatever you want. Blue is FULL BLUE (0, 0, 255, 255) and green is FULL GREEN (0, 255, 0, 255) in the stroke definition. No need to put things in layers or have separate SVG files any more, just make sure the line colors are what type of cut you want and export once. No copy pasting gcode files together either! The paths are all sorted to try to minimize travel moves, so all the cuts will be mixed in together instead of being completely separate passes. Note that the light blue color FT uses to declare A / B / C fold is not considered blue. Only fully blue things are blue!

IN ADDITION! If there is a file named "header" or "footer" in the destination directory, those are prepended and appended to the gcode file automatically. I have this as my header to pause 10 seconds then start the motor
Code:
G4 P10
M4 S70
and this is my footer to just stop the motor
Code:
M4 S0
Hopefully this will save everyone some time going through the files multiple times and deleting a bajillion lines and oops I saved over the wrong file.

INSTALLATION: Just extract the two files from the ZIP and put them in the Inkscape extensions directory (Inkscape/share/extensions/) not a subfolder, and it has the same title as ERC's (MI GRBL Z-AXIS Servo Controller). Note that it still has issues with the latest Inkscape (both 1.0 and 0.92) so Inkscape 0.91 r13725 should still be used.
 

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I just finished building the machine and I'm having an issue with some slop in circle cuts. Look at the image below...

IMG_20200511_111500.jpg


My circles keep undercutting along the X axis. I've checked everything and taken the slop out. Do you think the needle is bending? I'm using 8500 RPM and only going at 500 mm/min. I'm at a loss! I'm thinking about trying a pen attachment just to make sure it's not an issue with anything else.
 
Since I don't have much room I decided to build a cnc and a 3d printer in the same chassis
For the needle cutter I use a string from an old bass guitar by removing the winding string and using the core with two 0.4mm drilled to 0.6mm nozzles without bearings and the first test without knowing the revolutions and with an emax CF2822 1200kv is this

IMG_20200511_203028.jpg

the printer picks up the bed and leaves the base of the structure for the CNC, the cutter is removed to mount a laser and a dremel as needed

IMG_20200511_203058.jpg


I have it turned because I am still working on the 3D printer
 

Keno

Well-known member
Finally got my motor and got rid of all that extra wiring that came from using my other motor and nice ESC. Now using an old 12A EMAX from an Power Pack A. I think it looks so pretty that I even took it outside for a stroll.

View attachment 166974
View attachment 166975

The motor has a 3mm long shaft so the screw I was using to attach it to the motor shaft caused it to tilt as it wasn't fully engaged on the motor shaft. Luckily, there are M3 bolt holes in the top so I redesigned again and now the grub screw is the counterweight. I had to increase the stroke to 8mm to have space for the mounting bolt heads but it runs even quieter than before with 2x washers on the grub-terweight.

The needle is already chewing through the 3D printer nozzle though. I guess it is pretty thin brass there at the tip so at some point down the road I'll probably need to get a welding tip. The bottom-right wheel on the needle's mountplate was a teensy bit loose so I just wrapped a couple wraps of PTFE tape around it. Testing has gone well though and I just need to make a new homing plate to account for the new needle/motor geometry. I did pretty good at just using spare parts to build this:
  • OpenBuilds V-Slot 2040x1m and 2020x1m - $35.01 shipped
  • 2212 930KV brushless motor - $9 shipped from eBay WHAT
  • CNC Shield - $9 shipped
  • $53 out of pocket and only about 100 hours of 3D design and problem-solving
First thing I think I am going to cut is an FT Sparrow and make a 3 channel glider out of it. I have nowhere to fly so I might enjoy building a launching mechanism and gliding around the cul-de-sac. Maybe even FPV if I want to throw up on launch!
This is the best needle cutter head design that has been offered in my opinion. I do not use this machine but found though trial and error to adopt its design.

For added thought on others post, the issue of out of round holes is maybe your rails or arms need more support or hopefully just some screws need to tightened. My experience with guide bearing is you are better off with out them, mine just wore out the needle faster (needle flapping on them). I use two bearing in line to support the needle shaft for stability, longer life and smooth rotation. The problem with pressing two bearings together is you need something between them apart to allow bearing to rotate independently. I added a splash shield around the welding nozzle entry point and use synthetic grease for lubrication. Happy building
 

epsilon

Active member
I mean... not like this wasn't expected even before Edward gave us the heads up. If an amazon shipment that normally takes a day or two max now takes a week or two it just makes sense that something coming from china is going to be a big ??? ... anyway... i know, it's hard to be patient with something so exciting.
 
How many other people are finding their TimSav is reportedly stuck in China in a distribution center for the last three weeks? Is this normal or are they sitting on them because of all the mean stuff Donald has been saying? Or are they actually on the proverbial "slow boat".

The wait would be easier if we understood why it seems to be just sitting there.
 

epsilon

Active member
How many other people are finding their TimSav is reportedly stuck in China in a distribution center for the last three weeks? Is this normal or are they sitting on them because of all the mean stuff Donald has been saying? Or are they actually on the proverbial "slow boat".

The wait would be easier if we understood why it seems to be just sitting there.

Not sure there's any "official" answer to this question but seeing as how half the world is still shutdown over the current state of affairs, this is to be expected. Edward made mention recently that a lot of shipments piggyback onto commercial flights. Again, seeing as how flights are significantly cut back at the moment it's simply another side affect of the current circumstances. I was reading recently that physical gold is hitting the same problem, it often is transported on commercial flights and as such, is next to impossible to find now since they can't get it moved from one place to another. I certainly understand the frustration, especially if you were in an earlier batch that was already underway before all this began but what can anyone do? Least i had the opportunity to set my expectation to potentially have to wait 30-60 days.