ERC TimSav - Cheap DIY CNC Foamboard Cutter

[dkj4linux]

So my kit arrived in late June, It has been assembled, tested and calibrated and seems to work very well, except I am struggling with needle breakage right at the flex point near the top of the two rows of bearings that guide the needle down into the MIG tip. I can get through a single sheet on a needle, but never two in a row. the "PING!" noise the needle makes is exhilarating, but I could do with hearing it a lot less frequently. Interestingly, the parts list calls for .6mm wire, but the pre-made needles I received were at most .4mm (still look to be 304 stainless). I bought a spool of 20 gauge steel wire that measures .58mm and it will not fit between the bearing guides. I am running the cutter motor at 8500-8900 rpm, the needle has been sharpened quite well using a Dremel and fine grinding wheel. When the needle is in one piece, my cuts are pretty sharp and clean, although I noticed some fine alignment issues that look like they're due to slop in the Z-axis motor plate. I am considering building this: ERC TimSav ball bearing head

I would really welcome advice on both diagnosis and what needle material I should be using (if this has been discussed earlier, I apologize; I read through the thread as best I could, along with Cutting foam sheets... with a needle!, but i Could easily have missed it since there is an absolute trove of information there. I took the advice posted earlier and have been running the JTech Inkscape plugin and am impressed; it is no more difficult to use than GRBL but more flexible and up-to-date.

FWIW, I found that importing the plans into a CAD program, converting all the spline curves to closed polylines and fixing the teeny, tiny mismatches and poor intersections that importing brings along make for quick work in Inkscape, without excessive Z-Axis changes and clean joinery. Importing as a DXF seems to keep things tight, and allows me to completely rearrange plan sheets to minimize waste.

I have always used, and recommended, 0.025" (0.635mm) music-wire... it's high-carbon "spring" steel (designed to bend). The 20 gauge steel wire you tried looks to be 0.035" (0.89mm) and I'm not real surprised that it's too large to go between the guide bearings. I do not recommend the spooled wire that Edward (and many others) used... but the 36" straight stuff, like this K&S wire from Amazon. It is crucial when fabbing new needles that you do not create "stress risers" (nicks/scuffs) or bend more than once... use round-jaw pliers. Take care forming the needle and loops and, with practice, it shouldn't take more than a couple of minutes to make a good needle. Also try to "center" the angle the needle makes as it exits from the loops (don't come off at a tangent to the loops)... to equalize the amount of bend on both the up and down stroke. I like to observe the conical "blur" as the cutter runs... it should be symmetrical, not bending more to one side than the other.

I've also heard of some who have removed the top tow guide bearing to ease the severity of the bend the needle experiences with each rotation but I wouldn't do that except as as last resort... it largely defeats the purpose of having the bearing array in the first place [to constrain the needle's motion to up-and-down *before* it enters the main (MIG-tip) guide]. If you feel this is necessary, I'd go ahead and remove the bottom bearings as well... and then you have the basic cutter that I started with.

I'd recommend trying the 0.025" music-wire first and see if that doesn't help. Also, check that your RPM's are really 8500 rpm (or less). Don't guess or "play it by ear"... you'll almost always be running too fast if you do. This is IMHO the most common mistake made by first-time needle cutter builders/users. I'd also recommend getting a inexpensive optical tach... just to be sure.

-- David

 

[jpot1]

Hobby Lobby is a good source for the 0.025” diameter music wire mentioned by @dkj4linux . 4 pieces for $1.99 assuming you have one nearby.

My latest problem I’m looking for help with. I was using Inkscape 0.92 with the Jtech plugin to create my gcode. Everything was fine until I opened Inkscape today and it had upgraded itself to v1.0. Downloaded the beta Jtech v1.0 plugin but it’s throwing errors.

Has anyone got it to work or is the plugin recommended by Edward working for anyone in Inkscape 1.0?

 

[kevbospr]

Thanks very much for the reply; I have .029 music wire on order, should be here Wednesday. Nothing I can find locally is high carbon or stainless, and I think mild steel will likely work harden at the flex point and break even faster. I do in fact have a cheap laser tach and even put a little swatch of the reflective material on my flywheel to ensure accurate results. I am wondering about a little-more sophisticated servo tester as the little potentiometer-based one seems to have a high degree of variability and I like things to be repeatable.

I am loathe to remove any of the bearing guides except as a last resort, and would even go to a redesigned cutter head before removing features from an existing design; I've seen an alternative arrangement here in the forums that might be interesting.

Again, I really appreciate your advice!

 

[kevbospr]

Hobby Lobby is a good source for the 0.025” diameter music wire mentioned by @dkj4linux . 4 pieces for $1.99 assuming you have one nearby.

My latest problem I’m looking for help with. I was using Inkscape 0.92 with the Jtech plugin to create my gcode. Everything was fine until I opened Inkscape today and it had upgraded itself to v1.0. Downloaded the beta Jtech v1.0 plugin but it’s throwing errors.

Has anyone got it to work or is the plugin recommended by Edward working for anyone in Inkscape 1.0?

My local Hobby Lobby has the most minimal selection of music wire you could imagine, just a few carded strands of 18 gauge. It would be easier to just uninstall Inkscape 1.0 and reinstall 0.925, my PC runs an application called PatchMyPC that inadvertently upgraded my Inkscape to V. 1.0 and it was a snap to remove and reinstall the older version. There's nothing written to the registry by Inkscape, it removes completely when you use the Windows Control Panel "remove program".

 

[kevbospr]

Thanks very much for the reply; I have .029 music wire on order, should be here Wednesday. Nothing I can find locally is high carbon or stainless, and I think mild steel will likely work harden at the flex point and break even faster. I do in fact have a cheap laser tach and even put a little swatch of the reflective material on my flywheel to ensure accurate results. I am wondering about a little-more sophisticated servo tester as the little potentiometer-based one seems to have a high degree of variability and I like things to be repeatable.

I am loathe to remove any of the bearing guides except as a last resort, and would even go to a redesigned cutter head before removing features from an existing design; I've seen an alternative arrangement here in the forums that might be interesting.

Again, I really appreciate your advice!

Oops, should have posted this as a reply to dkj4linux's response to me. please forgive my faux pas.

 

[dkj4linux]

I've shared this a few times over the years... but early on I didn't have access to music-wire and did relatively little online shopping. But the local big-box store had 0.025" Mig-wire and I used the following method -- I call it "twist-straightening" -- to make quite good needles for many of my early cutters. Not quite as good as music-wire but it definitely worked well for needle-cutting the fanfold, bluecore, insulation foam my late fishing/flying/golfing buddy and I were using to build RC airplanes to fly in my pasture. We had great fun!

==============
I found the following photos that show twist-straightening a piece of 0.025" Mig-wire fresh off the spool. You'll need a strong vice, a power drill, a big enough hook to chuck up in the drill, and a 30"-36" piece of wire to be straightened. Form a small, sturdy eye on one end of the wire, hook it with the hook in the drill chuck, and a *securely* clamp/capture the other end of the wire in the vise.

Standing on the vice, I then pull upward until the wire is taut... and then power on the drill motor while keeping the tension. In this case I think I probably just kept going until the wire broke... and it's standing straight up on its own; i.e. I'm not holding it up at all...

Removed from the vice, the wire is perfectly straight...

and ready to be formed into a needle. I made many needles this way early-on, before I started using piano-wire...

This has straightened all the kinds of wire I've ever tried... solid copper electrical wire, baling wire, Mig-wire, galvanized wire, etc. I'm not sure about piano-wire (I've only used the straight stuff) but I'll bet it will. It will work-harden and probably not have quite the tensile strength it once had but it works nicely if you just need a straight, stiff, piece of wire...

========================

-- David

 

[dutchmonkey]

So my kit arrived in late June, It has been assembled, tested and calibrated and seems to work very well, except I am struggling with needle breakage right at the flex point near the top of the two rows of bearings that guide the needle down into the MIG tip. I can get through a single sheet on a needle, but never two in a row. the "PING!" noise the needle makes is exhilarating, but I could do with hearing it a lot less frequently. Interestingly, the parts list calls for .6mm wire, but the pre-made needles I received were at most .4mm (still look to be 304 stainless). I bought a spool of 20 gauge steel wire that measures .58mm and it will not fit between the bearing guides. I am running the cutter motor at 8500-8900 rpm, the needle has been sharpened quite well using a Dremel and fine grinding wheel. When the needle is in one piece, my cuts are pretty sharp and clean, although I noticed some fine alignment issues that look like they're due to slop in the Z-axis motor plate. I am considering building this: ERC TimSav ball bearing head

I would really welcome advice on both diagnosis and what needle material I should be using (if this has been discussed earlier, I apologize; I read through the thread as best I could, along with Cutting foam sheets... with a needle!, but i Could easily have missed it since there is an absolute trove of information there. I took the advice posted earlier and have been running the JTech Inkscape plugin and am impressed; it is no more difficult to use than GRBL but more flexible and up-to-date.

FWIW, I found that importing the plans into a CAD program, converting all the spline curves to closed polylines and fixing the teeny, tiny mismatches and poor intersections that importing brings along make for quick work in Inkscape, without excessive Z-Axis changes and clean joinery. Importing as a DXF seems to keep things tight, and allows me to completely rearrange plan sheets to minimize waste.

Back towards the front of this thread i posted a flanged bearing that fixed my needle snaping issue. It would get caught behind the bearing and snap time for a new needle. I have cut 30 sheets with the same needle just resharpend it

 

[Matagami Designs]

@kevbospr the ERC Timsav ball bearing head that Zerok posted on thingiverse should help a lot with your needle breaking issue. If you notice the motor has been raised higher from the bearing guides. This makes it so the wire experiences a lot less strain it and doesn't fatigue quite as quickly. I initially did this on my printed V-rail mount which can be found in the Facebook group files. Zerok was able to take this to the next level and added some fancy pen holders and gear attachment for the servo. There is even another mod posted by David Corscadden on the Facebook group which takes the v rail mount and adds the gear attachment with no pen. This is the one i am using now as there are no new parts i need to purchase besides what comes with the kit already. Attached is what the v rail mount mod looks like. If you haven't already i would recommend joining the Facebook group as there are many more resources and friendly people there as well.

 

[kevbospr]

@kevbospr the ERC Timsav ball bearing head that Zerok posted on thingiverse should help a lot with your needle breaking issue. If you notice the motor has been raised higher from the bearing guides. This makes it so the wire experiences a lot less strain it and doesn't fatigue quite as quickly. I initially did this on my printed V-rail mount which can be found in the Facebook group files. Zerok was able to take this to the next level and added some fancy pen holders and gear attachment for the servo. There is even another mod posted by David Corscadden on the Facebook group which takes the v rail mount and adds the gear attachment with no pen. This is the one i am using now as there are no new parts i need to purchase besides what comes with the kit already. Attached is what the v rail mount mod looks like. If you haven't already i would recommend joining the Facebook group as there are many more resources and friendly people there as well.

Thanks for the info, I think I have the Ball Bearing head you described downloaded and will be printing it soon; if I have the right one, it looks quite different from the image you posted https://www.thingiverse.com/thing:4330662. I may have to break a longstanding rule and join Facebook; I have resisted all these years because I am an IT professional and DESPISE the way Facebook treats user data, but there are too many useful forums, etc. We'll see.

The community here on the Flitetest forums is amazing; I love how helpful and friendly everyone is, and I have learned much and had nothing but positive, excellent interactions. Many thanks to you (again) for the Master Series P-38 parts, that'll be the 2nd or 3rd build once the needle cutter is behaving reliably (P-47 Thunderbolt 1st, possibly spitfire 2nd, I should be ready to form booms after a couple of practice runs).

Thanks again!

 

[kevbospr]

I've shared this a few times over the years... but early on I didn't have access to music-wire and did relatively little online shopping. But the local big-box store had 0.025" Mig-wire and I used the following method -- I call it "twist-straightening" -- to make quite good needles for many of my early cutters. Not quite as good as music-wire but it definitely worked well for needle-cutting the fanfold, bluecore, insulation foam my late fishing/flying/golfing buddy and I were using to build RC airplanes to fly in my pasture. We had great fun!

==============
I found the following photos that show twist-straightening a piece of 0.025" Mig-wire fresh off the spool. You'll need a strong vice, a power drill, a big enough hook to chuck up in the drill, and a 30"-36" piece of wire to be straightened. Form a small, sturdy eye on one end of the wire, hook it with the hook in the drill chuck, and a *securely* clamp/capture the other end of the wire in the vise.

Standing on the vice, I then pull upward until the wire is taut... and then power on the drill motor while keeping the tension. In this case I think I probably just kept going until the wire broke... and it's standing straight up on its own; i.e. I'm not holding it up at all...

Removed from the vice, the wire is perfectly straight...

and ready to be formed into a needle. I made many needles this way early-on, before I started using piano-wire...

This has straightened all the kinds of wire I've ever tried... solid copper electrical wire, baling wire, Mig-wire, galvanized wire, etc. I'm not sure about piano-wire (I've only used the straight stuff) but I'll bet it will. It will work-harden and probably not have quite the tensile strength it once had but it works nicely if you just need a straight, stiff, piece of wire...

========================

-- David

I've seen that trick before! My father was a welder and had all kinds of homemade jigs for steelworking. I am almost certain we used the same method a few times, but for much thicker material (and a lot bigger drill motor!). I do think it work-hardens the steel a bit, but I admit I had forgotten this process and I am sure it will be useful, even if I don't make needles out of MIG wire (very clever, that - my welder is a cheap flux-core, probably just make a mess and ruin expensive wire). I think I am going to print a redesigned ball-bearing based cutter head assembly (https://www.thingiverse.com/thing:4330662) that moves the motor up quite a bit, which should make the flexing less severe. I would kil two birds with one stone that way, as the slopiness of the slotted plate and screw mounting for the motor plate seems to be responsible for the slight end-to-end alignment issues (i.e. starts and ends don't always line up, and I can see the motor plate moving from side-to-side slightly during printing).

For me, the fun is finding the tweaks that hone the operation of a machine to a finer "edge"; I enjoy printing things to improve my Creality Ender3 and "rebuilding" it as much as creating things to do "real" stuff; I am rusty as can be in CAD, as that's how I started in IT, but it was a long time ago and I am dusting off old skills again to start creating and not rely on the kindness of Thingiverse posters (although there's nothing wrong with that, and there's fantastic ideas there). Just another step on the journey...

Thanks again for the excellent information; I will post again once the wire arrives and I start testing solutions!

 

[kevbospr]

Back towards the front of this thread i posted a flanged bearing that fixed my needle snaping issue. It would get caught behind the bearing and snap time for a new needle. I have cut 30 sheets with the same needle just resharpend it

I remembered seeing that, there's no evidence my needles are getting stuck, but I will keep an eye on that. seems like you created an easy solution for a tricky problem! I might be ordering some teeny little bearings soon.

Thanks for the reminder!

 

[kevinp]

It's been almost three months now since I ordered my kit..... sigh.

 

[Keno]

From all the info and different designs this is the one that works for me. As noted the throw need to be 1-1/2+ above the entry into the nozzle is what I found best. note no guide bearing they wore out the needle because "wire slap". With use of set screw to hold the needle on the flywheel it is easy to replace. I lube the needle with small amounts of syn. grease that is why you see splash shields on the sides. Well anyway it works for me. Happy building.

 

[kevbospr]

Time for testing! I did (what was for me) something unthinkable, joined Facebook and spend the last week plowing through the ERC TimSav group and incorporating all that information with everything I've read here. @dutchmonkey , I ordered flanged bearings from Amazon, at $10 it was a cheap experiment. I printed the X-Tensioner & support from the Facebook group, which seemed MUCH less prone to flexing on the far end of the 2020 X-carrier extrusion, and modified the Y-plates in TinkerCAD to add a second rolling support and standoffs to tie the end of the Y-plates together as the stepper motors flexed a lot on the Y-plates and I don't like things dangling. @Matagami Designs, I also printed Zerok's improved cutter assembly, which relies on linear ball bearings and has no flex or slop, but is smooth as glass. Gonna be doing a lot of cutting this weekend!
.

 

[kevbospr]

As my father used to say, "Up jumped the devil!": I got everything powered up, had a few missed attempts connecting, finally got going and had the cutter stop 1/3 of the way through. Reset, tried again, got a little further. Powered everything down, took a very close look at wiring connections, stepper driver connections, CNCShield-to-Arduino connection, tried again. Got all the way to 1/2 , died again. I issued a stop in GRBL, then a close / reset and got the attached garbled response. It feels like a connectivity issue, or a sick CNCShield or Arduino. No magic blue smoke coming out, nothing even warm to the touch, just stop and freeze. I would value any thoughts anyone has...

 

[GrizWiz]

Does Someone have pdf files if you wanted to make some of the 3d printed parts with plywood

 

[GrizWiz]

or measurements for the flat parts

 

[kevinp]

You could import the STL files into TinkerCad or some other program and measure off the grid or measuring tool.

 

[GrizWiz]

I used a 3d cad measuring software than took screenshots and brought them into inkscape

 

[GrizWiz]

here are two pdf with the parts