Cutting foam sheets... with a needle!

dkj4linux

Elite member
Decided to go for it. The laser seemed to be functioning properly and things looked really good for a while…


until… sadly – and quite unexpectedly – the raster exhibits skew in X as it progresses from bottom to top. To top it all off, the raster also seems compressed in Y and prematurely “finishes” without ever doing the dark top border and the profile cut (as on right in last photo). Obviously, a few things I need to go look at.







The message seems quite appropriate, don’t you think? … “I shall endeavor to persevere.”

stuck_out_tongue_winking_eye.png
thinking.png


– David
 

Notnewton

Member
I have the 3.5W version of that laser. Is there any benefit to running using the ttl line vs just pwm on the 12 V using the fan output?
 

dkj4linux

Elite member
I have the 3.5W version of that laser. Is there any benefit to running using the ttl line vs just pwm on the 12 V using the fan output?
I also have a couple of the Banggood 3.5 watt lasers but I still use the +5v PWM input for intensity control. Modulating the +12v power (such as with the fan signal) will indeed work but it's just ON/OFF control... kinda like controlling the room's lighting from the breaker panel. Dithering works well, however, for images but there is no true grayscale.

Is there a particular reason you don't want to hook up the TTL/PWM input? What CNC control board are you using? What firmware... Marlin? Grbl? If Marlin, I was able to remap the D9 fan signal to a +5v PWM pin (on RAMPS, it was pin 44... miniRambo it was the Z-min pin IIRC) and use M106/M107 for intensity control... it worked well. With Grbl v1.1f and later, I use "laser mode" and M4/M5 for control.

-- David
 

dkj4linux

Elite member
When last I left off I was astonished at what I was seeing… a skewed raster image. TBH from the beginning, I fully expected to have the put training wheels on the machine to keep it from running off the side of the road. What I didn’t expect was that it would gradually creep down the road in the same direction it was traveling.

So, after pondering things half the night – micro-stepping, dpi, etc. – I started not-so-fresh this morning. I decided to use a smaller image and try again. This ran to conclusion, complete with the expected raster skew… and kinda surrounded by a perfectly square vector/profile cut! Whut tha… ???



So, I decided to try a vertically scanned image to see what I could see… and fully expected to see the image skew along the Y axis this time. But, surprisingly, I got a nice, square image out of it…






Of note, my X-axis is the direction the tractors roll… and where the skew takes place. Since these have printed 78-tooth pulleys affixed to the wheels, the steps/mm setting is pretty ugly – 169.473. In the Y-axis, things are cleaner… motor, pulley, idler, and GT2 belt… steps/mm is 160.000. Since vertical scanning made a dramatic difference, I then began to suspect “rounding errors”… with the poor, little Nano just unable to keep up. So then I rounded the NASTY-looking 169.473 to 170.000… and then 160.000… and I still get the skewed images (top two of the middle 5 images)…



It does appear there may be a little less slant to the top two images but it still ain’t right. So, grasping at straws, I began to wonder if it was possible I was “slipping the tires” a little and changed the X-axis acceleration from 100 to 50… the middle-left image appears virtually the same.

The easy way out, of course, is to simply sit at end of the table (or turn the machine 90*) and swap the X and Y axes. Given the short door cut-off serving as the work surface, it would look perfectly normal using it that way. There’d be less mass moving on horizontally-scanned images that way as well… though my FoamRipper doesn’t seem to have the issue, with an even bigger, heavier gantry, and did the Chief Dan George image I used for comparison.

So I’ll turn the machine 90* and swap the X and Y axes, temporarily. But I’m really at a loss as to why I’m seeing this now… and never before, in the some several laser machines I’ve built in the past???

Any ideas? All you “brains” out there? And, yes… I did check all the grub screws ;)

– David
 

TEAJR66

Flite is good
Mentor
Time to put a Flite Control Board on that thing. Let the G-code set the way points, and let it loose on the wood floors. You could have all the fancy arts burned into the floor.
 

Boberticus

Active member
With the latest in RTK technology, you can achieve a sub 1cm accuracy!!!!!

using PPK and a powerful computer, you can be even more accurate than that! Granted, you will only be able to say, "man i was off by that much (~.5cm)" after the cut(and post processing), but why bother picking up a ruler when your technology can do the work for you!!!!

Facebook's latest release, CAM powered by occulus rift, inside out tracking allows you to become the machine. sculpt, shape, and make whatever you want, then program your CNC machine to make whatever you can think up, over and over agian. failed print/etch/carve automatic detection abort included with purchase!!!!


real talk though, were going to be messing around with this sorta stuff within the decade. that stuff is already changing the surveying and construction world. im pretty sure ive already seen failed print detection for klipper
 

jhitesma

Some guy in the desert
Mentor
Looking good David. I've been having some laser "fun" of my own. One of my electronics projects is going to need a case, and it's a bit big to 3D print...plus I want something really finished looking. So I decided to get the k40 going and see if I can't cut it out of black acrylic.

I should probably update my laser thread with the details...maybe I'll do that tonight. But short version - I had to finally remove the exhaust duct so I could fit 12"x12" stock in there. Which meant having to remove the laser tube itself because one of the bolts that holds one of it's mounts was in the way. And that in turn means now I get to have the fun of re-aligning the tube and the mirrors. Which...is proving to be just as tedious and annoying as I had expected it to be. But - it also gave me an excuse to install the upgraded mirrors I had bought and never installed because I didn't want to deal with laser alignment. And I installed a power pot finally so I can test fire it at very low power. Oh, and I designed and 3d printed some risers to hold the expanded metal bed finally. So it's close to usable again...just...need to finish this annoying alignment procedure.

The same project also got me to dive into a new form of 3D printing. I decided to try SLS resin printing. I almost went with the Anycubic photon zero since at just $170 it's dirt cheap and had decent reviews. But the more I watched/read the reviews the more I realized what most of the reviewers really liked was the wash/cure station that was released along with it. It actaully has noticably lower resolution than other SLS printers - and the whole reason I want it is to print small functional parts like knobs and buttons that are too small to do to my liking on my FDM printers. Yeah...I can print them on FDM...but they're so small they just don't look right with the layer lines even printed at 0.10mm. I even tried printing them in ABS and vapor smoothing them...but they just don't look consistent enough then.

20200617_225918.jpg


FWIW - buying these knobs isn't really an option. They're for special fancy dual rotary encoders (i.e. one encoder but with nested shafts so they can act as two separate encoders) and no stores that sell to consumers sell them in quantities of less than 1,000. I only need 4 so that would just be silly.

I've actually wanted to try SLS printing since before I even got my first FDM printer...so this was really just an excuse to finally try it :)

I did some research on other <$300 SLS printers and decided that the Phrozen Sonic Mini sounded like the one I'd be happiest with. It got really good reviews from a bunch of places and is apparently way faster than most others because it uses a monochrome LCD for it's mask that lets more UV light through. Most printers in this range do layers in 5-8 seconds. The Sonic mini does them in 2-4 so that makes it significantly faster. It did have a few flaws when first released but the biggest (a weak plastic resin vat) has been upgraded to an aluminum one. The other big flaw is the stock build plate is rather poorly designed and hard to clean after printing...but there's a replacement available now with a slanted back that solves that. Unfortunately it was out of stock on Amazon so I wound up ordering from a distributor who claimed 2 day fed-ex shipping and that they shipped out products in 3-6 days.

First bummer was having to actually pay for shipping. That bumped the price up $60. But they sold the upgraded build plate for half the cost it sells for on Amazon and it was also out of stock on Amazon as well - so that saves $20 which helped offset the bummer about shipping price. The next issue was they took longer than the 3-6 days to ship. Apparently the "distributor" I bought from doesn't actually maintain inventory - they just drop-ship direct from the manufacturer. And the manufacturer closed their shop for a week for a dragon boat festival the day after I ordered. Great. I e-mailed the distributor asking when I could expect shipping...and when I hadn't heard back in 24 hours got ready to dispute the charges with paypal and/or my credit card company and put plan B into action.

I ordered an Elegoo Mars Pro off of Amazon. The Mars Pro was about the same price as the Sonic...and has an upgraded UV lamp that makes it slower than the Sonic but still faster than other <$300 printers. It was also in stock with prime delivery in 3 days. The day after Amazon shipped the Mars pro I finally got a shipping notice on the Sonic - and sure enough it was 2 day shipping from Taiwan.

The mars pro arrived yesterday. Setup took all of 10 minutes. But my first two test prints failed:

20200702_132024.jpg


20200702_155016.jpg


The prints were sticking to the FEP film at the bottom of the vat instead of the build plate. Still the part that did print showed enough detail to get me excited.

I wasn't sure if the problem was the white resin I was using (since this is a light based process color of resin can make a BIG difference in settings) since the stock test print was apparently prepared for grey resin...or if I had just done a poor job of leveling the build plate. So...I tossed caution to the wind and changed multiple variables. I re-leveled the bed and decided to try printing my knobs instead of the pre-sliced test file.

It worked!



20200702_191822.jpg


20200702_210313.jpg


It's hard to get a photo that shows the detail and finish on these but they're amazing! More like cast parts than printed parts! And while resin is brittle it's also very tough. I put one of these in my dremel hobby vise and wasn't able to break it in any orientation! They were also accurate enough to fit the encoders first try.

They aren't perfect. You'll notice there's some major elephant foot going on which caused issues for the top knobs. Also I want them in black not white (I have black resin but didn't want to clean the vat and switch resins yet) and the top knob is a tiny bit looser than I'd like and the lower one is a tiny bit tighter than I'd like. But for a first "real" try with my own sliced parts...huge success.

One thing to note. Since SLA printers do a whole layer at once it's kind of neat that I can put as many of these on the build plate as I can fit and it takes just as long as printing one. Which is nice when you want to do a lot of parts at once. But is a bit of a bummer that just printing one isn't any faster when you want to iterate a design or do a quick test of a setting change.

In fact - I didn't mention it but the test part was a 3 hour print but I couldn't even see if it was working or not until over 2 hours in because it was still down in the vat. So you have to let a print run for at least 2 hours before you can even get a hint of if it's working or not.

After the success with my knobs I tried the test file again. I overrode the exposure in the printer to lower it from 7 seconds per layer to 5 to compensate for the white resin but suspect it was really just re-leveling the print bed that got me success this time:

20200702_222311.jpg

20200702_222318.jpg


Note - this was still a bit wet from post processing. The detail on the words on top is astounding. I've seen photos of this test piece before but they don't do it justice. It's so detailed and so fine! There are no visible or noticeable layer lines of any kind. And the fine details that show through...just astounding!

Now note - I would still say a FDM printer is more useful and functional by far. It's also much more pleasant to use. The resin STINKS, but while printing with the cover on the smell isn't that bad (the mars pro even has a charcoal filter which seems to help) But cleaning the prints after is messy and annoying. The resin in addition to smelling bad can cause chemical burns so you have to wear nitrile gloves and wash the finished parts in isopropyl or denatured alcohol....both of which are almost impossible to find right now thanks to COVID. A popular alternative is a cleaner called "mean green" but I can't find any locally which leaves me with the next most popular option - Simple Green. I HATE the smell of simple green :( The smell of the simple green bothers me WAY more. And once washed parts need to be final cured under UV light. I can just stick them outside but I also got a little UV spot light for $20 off Amazon which I can stick in a foil lined boxed to take care of that in just a few minutes.

Standard resin is also very brittle. It's very hard...but not very tough. So ok for things like busts in models but not great for functional parts. But there are also "ABS Like" tough resins that cost a bit more but are supposedly less brittle. There's also a few flexible resins and you can blend them - people add the flexible to regular resin to make the regular resin less brittle. I picked up some of the flexible to try but haven't had a chance to give it a go yet.

And after last nights success...the printer I originally ordered showed up today.

20200703_112930.jpg


First print on it is running now. Overall first impression the mars pro is a more refined package that impresses me more. But the sonic seems to have a few nice things in it's favor in addition to it's speed.

So I'm going to have a hard time deciding which one to sell. I don't really have room for both (not sure I even have room for one!) so I shouldn't keep both. But I'll give them a workout for a week or so before I decide.
 

dkj4linux

Elite member
Wow! You've been busy, Jason! It's always good to hear from you.

I once thought a K40 might be in my future but I guess not... been finding plenty to do without going that route, I guess. I was actually starting to slow down a bit with some of the diode laser stuff as well... until @Bulldog, over on the Lightburn forum, started showing off some incredible almost photo-quality engravings on wood, kids' scratch pad, and even ceramic tile... all done with a 2.5 watt laser. He generously shared his "recipes" and I've had a lot of fun trying to duplicate his results... only limited success so far but good enough to be real encouraging.

On the 3d-printer front, I've been so happy with my Prusa's that I've never felt compelled to look around for something else. I understand about those knobs and such, however. Way back when I was an active electronics hobbyist after the Navy, in college, and then in industry... test equipment was a big deal to me, especially O-scopes. I used these machines every day... but they were so totally out of reach, $$$-wise, I was always dreaming of someday building my own. And if anything ever had on display, those concentric knobs, it was the scopes from the 60's and 70's. I had tons of those concentric/ganged switches and pots in my junk box to play with... and the knobs would have definitely been a problem, had I ever gotten that far toward building a working scope. Those knobs (and other pieces) you've shown are really stunning... far nicer than what you'd get from your FDM machine. Good work! All the post-processing involved, however, sounds daunting. I only make giant messes, nowadays, with anything involving liquids, glues, paint, solvents, etc.

Then SIL took on a large children's activities room decorating project at his church that involved a lot of construction foam that needed to be cut into a lot of interesting shapes. I duplicated the ERC TimSav minimalist CNC machine I had gotten... and used the two of them, slaved together and side-by-side, to make a hot-wire machine, which we used to cut a few shapes and some signage. After that project had run its course, I dismantled one of them and am using the extrusions and parts on my current project, the "rolling gantry" that I've been playing with for the last couple of pages.

I've not documented some the latest developments on the rolling gantry front in this thread... it was moving so fast. You can see more about the fun we've been having trying to figure out the causes of the "skew" I've been seeing, along the tractor's rolling axis, here. It's been a lot of fun.

Stay well, stay busy... and be sure to keep us up to date!

-- David
 

Notnewton

Member
I also have a couple of the Banggood 3.5 watt lasers but I still use the +5v PWM input for intensity control. Modulating the +12v power (such as with the fan signal) will indeed work but it's just ON/OFF control... kinda like controlling the room's lighting from the breaker panel. Dithering works well, however, for images but there is no true grayscale.

Is there a particular reason you don't want to hook up the TTL/PWM input? What CNC control board are you using? What firmware... Marlin? Grbl? If Marlin, I was able to remap the D9 fan signal to a +5v PWM pin (on RAMPS, it was pin 44... miniRambo it was the Z-min pin IIRC) and use M106/M107 for intensity control... it worked well. With Grbl v1.1f and later, I use "laser mode" and M4/M5 for control.

-- David

David,
I’m running the skr v1.3. Honestly i haven’t gotten to work with it much yet. I was going to plug signal in to the servo port and leave the 12V on the const on fan or power input but wasn’t sure how to modify marlin to control it. I plan on switching between the router, laser and needle cutter for various tasks. Haven’t got to the cutter yet either.
 

dkj4linux

Elite member
I don't have a SKR board so can't really give you specifics. But since you are using Marlin... here's the way I hooked up the laser on my Marlin-based machines.

The laser's Power input was simply hooked to the same +12v power as powers the controller, i.e. RAMPS, mini-Rambo, or SKR in your case. The part cooling fan signal (D9 for RAMPS, SKR ???) is a 12v signal and not suitable for direct connection to your laser's TTL/PWM pins (you run the risk of "blowing it out" with over-voltage), so it needs to be "remapped" (re-assigned) to a suitable +5v pin, capable of PWM (for RAMPS I used pin 44, for miniRambo it was the Z-min pin, for SKR ???). This "remapping" is a firmware edit ("pins_RAMPS.h" for RAMPS IIRC) to re-assign the part-cooling fan signal pin to an appropriate 5v pin to allow direct connection to your laser's TTL/PWM input and use of M106 SXXX to turn the laser on and M107 to turn the laser off. The Sxxx is the laser strength with a value between 0-255, 255 being the most power.

The Marlin firmware edit was very simple... finding *where* to apply it was the tricky part. For RAMPS, in the Heaters/Fans section of "pins_RAMPS.h", that's where I changed the RAMPS_D9_PIN value from 9 to 44. The variable itself should still be called RAMPS_D9_PIN ... it just has a new value assigned. I usually just duplicate the line, edit it, and comment out the original line just in case I should ever want to go back.
...
#ifndef RAMPS_D9_PIN
//#define RAMPS_D9_PIN 9
#define RAMPS_D9_PIN 44 // laser PWM - M106/M107
#endif
...

Hopefully this make some sense to you and you already know how to edit and flash the Marlin firmware to your SKR board. I'm using Grbl now for controlling most of my machines and am too far removed from setting up and using Marlin for laser control to be of much help. But the above is the gist of what needs to be done to control your laser with Marlin.

I recommend you get the needle cutter and router going before tackling the laser. They require no firmware edits for basic operation (manual on/off, etc) and will give you opportunity to learn the ins/outs of your particular machine.

Good luck.

-- David
 

TEAJR66

Flite is good
Mentor
David, where did source your extrusions?

Preamble: Marlin firmware and ramps boards provide all i need and they are pretty simple.
Question: Is there any reason i should source newer boards and different firmware, (other than personal growth)?

Im still working on my foam ripper-ish design. Progress is slow.
 

dkj4linux

Elite member
David, where did source your extrusions?

Preamble: Marlin firmware and ramps boards provide all i need and they are pretty simple.
Question: Is there any reason i should source newer boards and different firmware, (other than personal growth)?

Im still working on my foam ripper-ish design. Progress is slow.

Tommy, I initially sourced my V-slot 2020 and 2040 extrusion from Openbuilds. Good folks, reasonable prices, and fast delivery. It's what I used to build the 2nd TimSav machine... that eventually became part of the TimSavX2 hot-wire machine (now dismantled). I also found some cheapie V-slot online -- Banggood, though I believe that the 2020 and 2040 came from different stores/places -- and it took far longer to get here... but get here it finally did. It's the black extrusion I'm using with the rolling gantry.

I have used a number of controller boards now... and, poor FoamRipper, it's seen them all. But early on I was using Mega/RAMPS/Marlin almost exclusively. I had several of them and kept reusing them as machines came and went. Then, while helping trouble-shoot some laser issues over on the ViEngineeing forum, I set up a mini-Rambo board and got it running. Later I tried the MKS Gen L v1.0 -- which is supposedly Mega/RAMPS integrated into a single board -- and found it to be quite compatible and easy to use as well. Then I started playing around with Grbl and became quite a fan of its "laser mode" and the numerous, simple, inexpensive, Uno- and Nano-based 2- and 3-axis controllers it still loads up and runs on. Personally, I am very much more comfortable with Grbl now than with Marlin... especially if a laser is involved.

Good on you, working on a foam-ripper machine. I love having some sort of a current machine build going on. I feel it helps keep me "sharp" (as best I can) and from becoming bored, doing the same thing all the time.

Let me know how I can help and keep us posted on your progress. And... Happy 4th of July!

-- David
 

dkj4linux

Elite member
Alright! Leveled up my rolling gantry as best I could and started playing around…

I’m probably showing my age here… but I found this really good old sailboat picture. Ah, the graceful lines of the hull, the height of the masts, the cloth sails, the rigging, the sky, the water, the mountain in the background, and the rock in the foreground…



Really makes me wish I was there… in a simpler time, now long gone.

In the photos above, my X-axis is left-right and the rolling axis is Y… and engraving is horizontally-scanned along the X-axis. So I vertically-scanned (scan lines along the Y-axis) the same photo, with all other settings the same, and, of course, the skew becomes once again apparent.



I actually spent quite a long time trying to get this machine leveled up as best I could… and it amazes me those tractors’ sensitivity to the slope they are traversing. There’s gotta be something I’m missing here…

Well… holiday or no, I hope everyone enjoyed their 4th of July!

– David
 

dkj4linux

Elite member
Coming to a “command decision” in the middle of the night (as most of my “command decisions” do), after suddenly realizing how easy it would be to “belt up” like LR and FR… I decided that, for my purposes , “bullet-proof” is vastly superior to “touchy” and “sensitive”. So this morning I made the belt conversion…


and reran the skew test that had been so sensitive to “sub-millimeter” changes in “foot propped upped-ness”. The run on the left is done with the machine sitting flat on the floor and the one on the right has a 2x4 slipped under one foot of the 3-legged Jawhorse…




There’s no discernible difference that I can see…

For confirmation -- and because I can't get enough of that sailboat! -- here's that vertically scanned engraving that was skewing so badly...

20200705_141923.jpg


Every machine I’ve ever built – until now – has been pretty insensitive to how level (within reason) it’s been sitting and, as I’ve felt all along, they should be able to operate normally, even on a slight slope. But this one defied me and has had me “bum-fuzzled”… until now. I’m convinced that if you want the machine to accurately move over a worksurface… it needs to be anchored/tethered/referenced somehow to – and not independent of – that worksurface.

It’s no longer a [free-] Rolling Plotter, of course, but I’m pretty comfortable with what I’ve found out… and am ready to move on with my new, alternative, mini-FR gantry/playtoy. Most of the skew-related discussion and trouble-shooting took place over on the V1Engineering forum -- here -- but I genuinely appreciate everybody’s interest and kicking around all the ideas/suggestions/comments has been great fun… I love this stuff!

As always, please feel free to chime in if you have anything you want to add or offer up. Thank you all.

– David
 
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rbtoaks

Junior Member
David,
I am following up to see how much testing you have done with the Eric TimSav needle cutter on the MPCNC. I am finally getting around to assembling the Eric Timsav cutter for MPCNC conversion that you completed and the main MPCNC frame. I have a couple of questions.
1. Where do you source the bearings, and washers? I am only finding those size bearing from a china providerand various washers are one size.
2. Have you followed the modification that an individual did on raising the motor higher and changing the needle holding area? https://www.facebook.com/groups/erctimsav/permalink/1654725341342236/ What is your take on it? I just want to limit the breaking of needles.
3. Did you use or have used the welding tips and where did you source them?
4. Suggestion on needle material (thickness and type)?

Thank you for the great insight of this craft,
Robert
 

dkj4linux

Elite member
Robert,

I simply adapted the Edward's TimSav needle cutter to the MPCNC Burly tool plate. The needle cutter operates entirely as it would on TImSav... but will have the advantage of a real Z-axis on the MPCNC to lift the cutter and control depth of cut. I'm not actually doing any needle cutting nowadays --my plane building and flying days are over -- and I'm not really building new needle cutters so am not ordering the parts for them. Edward came along and started specifying parts and supporting his version of the cutter and I was happy to see him do it. His cutter was the closest thing to a standard cutter, and "kit" of standard parts, we've ever had... so I started pointing people toward it.

You need to refer to the BOM that Edward provided... it's all in his download materials out on Thingiverse. The reason I started "pushing" Edward's cutter is that, at the time, all the necessary parts were much more available for it than any of our previous cutters... but that was all before Covid. Being metric, most all those parts are still readily available for order from online sources... but delivery is, of course, another matter. The only critical part is the small-OD 3mm flat washers need to space out, and bear on, the inner race of the tiny bearings. They are extremely hard to get and of the several orders I've made, specifically for the smaller OD, not a single delivery has been anything but a common 3mm flat washer. One of the guys on the FB group (I despise FB and only looked in early on) had trouble getting the small-OD 3mm washers... so he ordered 2mm flat washers instead, epoxied them to a board, and then drilled them out on a drill press for 3mm. That'll work... it's just a pain.

I know you haven't had time to wade through this thread... but the needle cutter has been developed completely out in the open and all this information, and way more, is in there somewhere. Increasing/decreasing the motor shaft to main needle guide distance is a common way to control the severity of bend, and entry angle, the needle has to endure with every revolution. This, in turn, helps control the friction heating in the guide that, left unchecked, will eventually lead to catastrophic failure/seizure. The quad-bearing setup, above the main needle guide, in most recent cutters helps to constrain the motion of the needle in the main guide to basic up-and-down motion... and helps keep the friction heating to manageable levels.

I recommend needles that are fashioned from 0.025" piano-/music-wire... not the stuff on a roll (like Edward specified), but the straight 3' lengths sold in better hobby stores. And needles properly fitted around a bearing/post will generally last quite a long time... though fabricating them without stress risers (where breakage usually occurs) takes practice. I rarely had needles break, or fly off the bearing, unless I was torture-testing in cardboard/coroplast and/or running at much too high RPMs.

Athletic ball inflation needles were my first guides... and worked quite well with conservative feeds and speeds. I started using MIG-welding tips once we starting getting the friction heat a bit more under control. All the big-box stores (blue, orange, etc) carried them in the tools department with the welding stuff... and I have even found them at Walwart. Usually a card of 10 for just a few $$$.

i know it's a bit difficult to find information in this thread but the search function works well. I used it often to find information that I've forgotten "where it is" when I was doing more active needle cutter support. But there is tons of other good information, about all kinds of stuff, hidden in there as well... ;)

-- David
 

Dazzy

Active member
Hi David @dkj4linux , Ive been reading these post from yourself and others for sometime on and off and Im very keen to cut foam and alternately cut balsa as well based on the ideas put up in this forum. So I dont have access to a 3D printer atm, I have found what might get me around this problem ( no 3D printer ) and thats an
EleksMaker® EleksLaser-A3 Pro Laser Engraving Machine CNC Laser Printer
That I found on banggood, so Im curious if this kit would be suitable candidate for use as a needle cutter ( converted ) and maybe as a bonus as a balsa cutter?

Just a bit more, Id also like to convert this base machine to an A2 size cutter, that better suits cutting all of the FT Master series models like the Spitfire, Corsair etc.

Heres the link below, please check it out and give me an appraisal based on your experience and or others thoughts on this matter?

Thanks Darryl

Edit: Fwiw Im similar vintage to you and since retiring Im keen to be a more active member.

https://au.banggood.com/EleksMaker-...1JcYLQ3DPs7Z6-BoC4aQQAvD_BwE&cur_warehouse=CN
 
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dkj4linux

Elite member
Hey, Darryl! Welcome to our old-timers' club and humble abode...

It's pretty straight-forward to set up the Eleksmaker A3 machines as a needle cutter... and our own @Springer (another old-timer!) has done that very thing IIRC. Hopefully he will chime in here in a bit. I think he bought longer extrusions to enlarge his A3's work area and then built and made an adapter for his needle cutter. I'm sure he's done a few other things to it as well but I'll let him fill you in. I've got one of those A3 machines also but my daughter currently has it and is using it as a... well, laser engraver. Search back through the thread for "@Springer", "eleksmaker a3", etc and hopefully you'll find some useful information.

I'd really recommend looking into getting a 3d printer if you plan on doing more of this kind of stuff. I use mine all the time and would be lost without it. My planned next post will give you an idea of just how handy they can be for doing exactly this kind of work.

Again, welcome!

-- David
 

dkj4linux

Elite member
I’ve enjoyed playing a little with miniFR but am not happy with my Z-axis. So started looking around on Thingiverse and, remembering how impressed I was with a printed screw-drive linear slide by 3DPRINTINGWORLD, I found that he’d done a belt-driven slide as well. I printed it and put it together only to find that regular GT2 belt was a bit stiff for the slider channel and really didn’t attach securely to the carriage. He printed his belt with TPU, which I’ve never tried… and, on a lark, decided I should. Ordered Overture TPU, got it the next day, and actually managed to print a few belts on my MK3S. But this particular TPU, while flexible, is also quite elastic… and it really skipped teeth easily. So I decided to see what I might do to the carriage to enable regular GT2 belt to be used. I used FreeCAD to create a STEP model of the carriage and then imported that into Onshape, my CAD of choice. I plugged the posts and cavities where the TPU belts fastened and then created toothed channels for the GT2 belt.

Screenshot 2020-07-11 at 11.43.31 PM.png


So I rebuilt the slide with GT2 belt and now it seems much more robust and positive… and the little 28BYJ-48 is surprisingly strong when set up as a bipolar motor. That’s my bench vise (a couple of pounds) riding back and forth over 70mm range…


20200711_211315.jpg


20200711_211310.jpg


Satisfied that the slide looked like it was gonna work, I took a first cut at coming up with a new X-carriage to mount the slide on. The slider is noisy with all the BB’s recirculating in the race tracks with no lube… but of course this machine isn’t going to be doing tons of Z-moves anyway.


The first-cut X carriage plate will mount the “stock” slide but I can already see that I can open the end of the slider rail, remove the small stepper motor, and mount a small NEMA17 and drive pulley just above it and drive it with a more conventional stepper motor…

20200711_211834.jpg


This assembly will replace the carriage plate in the right background. While I was at it, I also widened the “wheelbase” and placed holes for wheels/axles for either 2020 or 2040, should I ever decide to beef it up a bit more.

Later.

– David
 
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