Cutting foam sheets... with a needle!

[x33]

Have had some nice results in cutting EPP with the needle this afternoon ... also set the motor to more "high speed" and did the tests with Depron again. ---> The bending wire has some resonance points by differnd motor-speeds - it seems to be a good idea to use a frequency outside of such a resonance point - the cutting will be more precise! I will test an ESC with Governore mode for this to optain a fixed speed.

Two more pics:

The CNC mill with the needle cutting head
http://www.jokr.de/cutter/cutter-15.jpg

needle cutter at work
http://www.jokr.de/cutter/cutter-16.jpg
You can see the parts coming out of the Depron sheet almost by itself.

The next goal is a (nearly) professional grade version (metal - no wood) of the cutter-head...then we can start cutting small planes for indoor flying
Thanx to all here for this great idea (especially to David)

Joachim

 

[dkj4linux]

Have had some nice results in cutting EPP with the needle this afternoon ... also set the motor to more "high speed" and did the tests with Depron again. ---> The bending wire has some resonance points by differnd motor-speeds - it seems to be a good idea to use a frequency outside of such a resonance point - the cutting will be more precise! I will test an ESC with Governore mode for this to optain a fixed speed.

Two more pics:

The CNC mill with the needle cutting head
http://www.jokr.de/cutter/cutter-15.jpg

needle cutter at work
http://www.jokr.de/cutter/cutter-16.jpg
You can see the parts coming out of the Depron sheet almost by itself.

The next goal is a (nearly) professional grade version (metal - no wood) of the cutter-head...then we can start cutting small planes for indoor flying
Thanx to all here for this great idea (especially to David)

Joachim

Outstanding, Joachim! I'm very encourged by those cuts... and anxious to see what the next version cutter looks like. Something seems a bit odd, however, building a heavy-duty, professional needle cutter for an industrial grade CNC machine to cut... of all things... super-light *indoor* planes

 

[dkj4linux]

First light!

After being side-tracked a couple of times, I finally hooked up the 3.5 watt Banggood laser.

The quick-change mounting clamp...



Laser and shroud mounted and power applied. TTL-controlled intensity and power worked first time...let there be light!



Focus setup -- removed shroud and improvised a secure fixture so I could get to the lens assembly...



Roughly set the surface to heatsink distance using a 55 mm gauge, low-power setting, and adjusted lens for smallest spot...



Ran Allted's focus test without shroud...

The focus pattern... count lines back to best focus and multiply by 2mm to determine how much to lower the laser to get to proper focus on top of material (here about 10 mm)...



Rerunning the focus test pattern with shroud affixed... note the smoke is pretty vigorously cleared by the air-blast coming from the nozzle of GremlinRC's shroud!

Running a couple of initial tests, it appears that my 2.8 watt laser cuts 5mm plywood as well as this one seems to. Running the same gcode files I can judge from the backside burn that there seems to be no real significant difference between the two. I had hoped that maybe I could cut in 3-4 passes rather than the 5 passes it takes with the 2.8 watt unit. I'll have to play with it some more but this was a bit of a disappointment. -- David

 

[x33]

Running a couple of initial tests, it appears that my 2.8 watt laser cuts 5mm plywood as well as this one....there seems to be no real significant difference between the two. -- David

Hi David,

do you realy trust the China-man's technical Datas.???

I've seen a post somewhere, that in some of this laserheads the Diode is only working "a little over the limits" to claim more power...I do not know if the is only a rumour....
If you will have a look on many of the "cheap" ESCs ...you will see only few transistors but a big heatsink for cooling (not a so good design ) - I also do not trust the Data (max Amp) on the BECs!!!!

I placed an order for this 3,5W laser (will take some weeks before arriving to Germany)...may be I can find out the true output power (my son is working at a technical university).
Very important is the possibility to refocus the laser beam at every pass via the Z-axis (as your system can do)....the cheap plottersystem (so called "laser-engraver" - without a Z-axis) does not have this advantage.

Joachim

P.S. your 3-D-Printwork looks fine!
I'm looking for a 3D-maschine since many month...but my time is limited...and I do not want to have an additional hobby

 

[GremlinRC]

Running a couple of initial tests, it appears that my 2.8 watt laser cuts 5mm plywood as well as this one seems to. Running the same gcode files I can judge from the backside burn that there seems to be no real significant difference between the two.

My first thought is to be absolutely certain that the PWM duty cycle is reaching 100%. However, I suppose when you think about it 3.5W is only 25% more power than your 2.8W model. The only way I have to test is to put a current meter inline. I will try that later. I know amp draw is not a true test of the power output but at least it will let us see what power is being used. If its a lot less than 3.5W then maybe we have a problem.

Have had some nice results in cutting EPP with the needle this afternoon

Well done Joachim, you certainly have had great success. I look forward to seeing your progress with the 'all metal' version. Mine is all metal but is very simple. My next task is to redesign mine, certainly including your extra two bearings for a needle guide. I also noted your comment about a 3d printer. If you can, just do it. I only have mine less than a week and I'm wondering how I ever lived without it. It's a game changer!

 

[dkj4linux]

Hi David,

do you realy trust the China-man's technical Datas.???

I've seen a post somewhere, that in some of this laserheads the Diode is only working "a little over the limits" to claim more power...I do not know if the is only a rumour....
If you will have a look on many of the "cheap" ESCs ...you will see only few transistors but a big heatsink for cooling (not a so good design ) - I also do not trust the Data (max Amp) on the BECs!!!!

I placed an order for this 3,5W laser (will take some weeks before arriving to Germany)...may be I can find out the true output power (my son is working at a technical university).
Very important is the possibility to refocus the laser beam at every pass via the Z-axis (as your system can do)....the cheap plottersystem (so called "laser-engraver" - without a Z-axis) does not have this advantage.

Joachim

P.S. your 3-D-Printwork looks fine!
I'm looking for a 3D-maschine since many month...but my time is limited...and I do not want to have an additional hobby

No, I really don't trust that the laser has been set up to spec... but hoped it might be close. And it is. I wouldn't have had anything to compare it to had I not already had the other laser up and running. And, in fairness, I purchased the 2.8 watt laser as individual components (driver and laser head) and I followed Leo69's fantastic setup procedure from the MPCNC site to set the current (1.7 amps at 5.5 volts) to the laser...

http://www.vicious1.com/the-2-8-watt-100-laser/

With the new laser I just hooked it up and turned it on... using the exact same Mega/RAMPS/firmware as with the 2.8 watt unit. I'm sure the two pots (with "pooky" on them) on the new laser driver board (2nd photo in my last post) are for voltage and current adjust and I should be able to figure out which is which and set the current up a bit more than is currently set. Both lasers are similar in power and I've still got the dummy load from before... so hopefully I should be able to roughly follow the same procedure to get that extra 25% out of it

As Dave says... move the 3d printer to the top of your priority list; i.e. it is indeed a "game changer". He seems to have gotten a really nice printer that is already mostly assembled and ready to go... that sculpted hand they furnished as a first test print looks fantastic straight off the printer. And, in the first week, he's already fixed a MP3 player for his wife and designed and printed the laser shroud that he generously shared and I now proudly have installed on my new laser head. Check out that last video in my previous post to see how vigorously and effectively it clears the smoke during the focus test... I really think, judging from that video and the quality of most of my previous cuts, that I've already got the "air-assist" that everybody is so excited about -- David

 

[GremlinRC]

... move the 3d printer to the top of your priority list; i.e. it is indeed a "game changer".

Just to emphasise that point, here's something else I've knocked up. A one bolt quick release mechanism for attaching my drag knife holder to my spindle. It's one of those 2.2kW chinese water cooled spindles with an 80mm diameter and a collar which is 10mm high and 72.15mm in diameter. That's where the holder clamps to. Going to do the same thing for my laser so I can interchange between these tools easily. The needle cutter is on a separate machine, but If I keep the same screw hole pattern as my standard then it will even ve an easy job to swap between machines too! Before the 3d printer that would have taken days of planning milling and generally hacking about. With the 3D printer the job is a simple one and more importantly repeatable and modifiable for future gadgets.




Cheers Dave.

 

[x33]

As Dave says... move the 3d printer to the top of your priority list; i.e. it is indeed a "game changer". -- David

...and this is my problem ==>> the printer is a very nice tool...
...and a real big toy...and I surely will spend at lot of time in "playing" with this thing

This printer will be like an additional hobby for me...
I like to go out for flying as often I can...and on days with bad weather I'm building/constructing small EPP/Depron-planes (or by now...a needle cuter )
I fear my situation will be like the guy with too many girlfriends --> one is fine --> two may be interessting --> bud three or even more at the same time are only "disturbing"

>I hope, you can understand what I'm trying to say - it is a little hard for me to express so complex thoughts in english<

On the other side: my friend (the guy with the big mill) is working with a 3d-Printer for nearly 2 years now...that makes it very easy for me to "order" some special printed parts...and I do not have to spend time or money...

-- My next step is to build the new needle cuttdoneer...and cutting the parts for a few sets of small Indoor-Shockflyers.
The CAD-works for this shocky are 90% done - two "hand cutted" prototypes are flying for a few weeks.
(if any interest? I will post some informations on it when the first needle cutted one is ready to fly)

-- Then I will have a try on the laser modul (hoping, not to run into serious troubles with the German customs...they are looking very closely on lasers with more than 1mW Output)

May be, a 3D-Printer could be an Item for NEXT Chrismas !!!!

Happy printing and cutting
Joachim

 

[GremlinRC]

This evening, I started thinking about the needle cutter again. I started off with the idea of redesigning it for 3D printing but then a realisation hit me. I've run this thing through about 10 sheets of foam at this stage and there is no sign of wear on the needle. I wonder why it hasn't worn out? Maybe its because its all metal and therefore dissapates the heat better. I did notice that even after an hour of constant running, only the motor got warm, the business end remained ambient. So maybe 'upgrading' to plastic is not the thing to do? I dunno.



There is a bit of wear around the needle guide (which is scrounged from an old airbrush). I ordered some mig welding tips 0.8mm to A: make that part easily replaceable. B: to better contain the needle so it doesn't wander inside the guide.



Also you can see the needle guide is about 5mm out of line with the motor. I'll take 5mm off the base block to bring this back into line.

I thought about to best to implement Joachim's guide bearings and if I do that, I think I need to mount them pretty close to the needle guide. I may well mill a new base block to incorporate the guide bearings but apart from that I think I'll leave it pretty much as is. "If it aint broke don't fix it".

Actually maybe I'll take that a step farther and leave this one alone completely and just make a whole new MK2 cutter with the improvements above and maybe a slightly higher KV motor.

Cheers

Dave.

 

[dkj4linux]

This evening, I started thinking about the needle cutter again. I started off with the idea of redesigning it for 3D printing but then a realisation hit me. I've run this thing through about 10 sheets of foam at this stage and there is no sign of wear on the needle. I wonder why it hasn't worn out? Maybe its because its all metal and therefore dissapates the heat better. I did notice that even after an hour of constant running, only the motor got warm, the business end remained ambient. So maybe 'upgrading' to plastic is not the thing to do? I dunno.

View attachment 79929

There is a bit of wear around the needle guide (which is scrounged from an old airbrush). I ordered some mig welding tips 0.8mm to A: make that part easily replaceable. B: to better contain the needle so it doesn't wander inside the guide.

View attachment 79930

Also you can see the needle guide is about 5mm out of line with the motor. I'll take 5mm off the base block to bring this back into line.

I thought about to best to implement Joachim's guide bearings and if I do that, I think I need to mount them pretty close to the needle guide. I may well mill a new base block to incorporate the guide bearings but apart from that I think I'll leave it pretty much as is. "If it aint broke don't fix it".

Actually maybe I'll take that a step farther and leave this one alone completely and just make a whole new MK2 cutter with the improvements above and maybe a slightly higher KV motor.

Cheers

Dave.

Dave,

When I shared my needle cutter with the world, I did so with an eye toward making it as simple and easy to build as possible for the masses... for folks who needed a tool that was "good enough" to cut a few sheets of foam for their airplanes but maybe didn't have machinist skills and/or a well-equipped workshop. I tried to identify and use common, readily available components and materials and never questioned that it could be made more robust but did resist recommending anything that drove up the complexity and/or made it more difficult to build for the masses. So that's what I supported in the forums and recommended for anyone who thought they might like to give it a try.

That said, there have been numerous successful needle cutters made by folks who do have the tools and skills to make it more robust and production-ready... such as yours, Joachim's, and others. Some became more complex and had other issues but, interestingly, the most successful have remained pretty close to the original design. The biggest issue with the 3d printed versions has been the friction-heat at the throat of the needle guide but those built of metal or wood are virtually immune (to the heat, not the friction)... as my originals were. Effective mods have been developed to make the 3d printed versions more heat-tolerant but the metal ones will almost certainly be more robust and longer-lasting... and you certainly have the skills and tools to make a really nice needle cutter; i.e. in your case, I'd stick with metal construction.

Yours has the potential to be one of the better ones... when the alignment issues have been addressed. I'm interested to see whether Joachim's guide bearing setup will really help but am not sure yet whether the bearings will oscillate freely with the rapidly moving needle or whether the bearings' inertia will simply cause the needle to slip and slide against their outer races.

Theoretically, it makes sense that the faster the cutter speed, the higher the feed rate that can be used and keep the perforations per unit distance in a good range to get clean cuts. So far, however, almost all cutters seem to cut a bit better toward the lower end of the feed/speed spectrum... even with the same perforations per unit distance. It also results in less wear/tear/stress on this admittedly primitive and somewhat sloppy mechanism -- David

 

[x33]

Dave,
I'm interested to see whether Joachim's guide bearing setup will really help but am not sure yet whether the bearings will oscillate freely with the rapidly moving needle or whether the bearings' inertia will simply cause the needle to slip and slide against their outer races. -- David

Hi David,

I tried to find out the movement of the bearings on my very first test....and you are right with both ideas

---> the needle is moving the bearings sometimes... ...and sometimes not!
The depends on how much the needle is bending to the outsides...
...and this depends on:
1. oscillation frequency (motor revs)
2. hitting a system resonance point (or not)
3. load on the needle pin when cutting/pinning

At first, I had a try with out the bearings and feared the danger in breaking the needle under worst case (high rev and big flexing movements, caused by hitting such a resonance. ..I feel much "safer" with the bearings!


you can see that the wire is running within a narrow wooden slot before the bearings...this wood is slightly grease (and is holding the grease for a longer time)...so the outside of the bearings will have some grease too.

A "funny" effect ---> sometimes the bearings are really spinning round and round...may be caused by some resonaces...


@David ---> a like the attitude to KIS (<K>eep <I>t <S>imple) very muuch...but a want to build the needle head as reliable as I can...it should be a real tool and I do not want to look for a "service" too often.
(...and I make it not only for me allone!)

Greetings from cold and rainy Germany
Joachim

 

[GremlinRC]

---> the needle is moving the bearings sometimes... ...and sometimes not!

I wonder if it matters too much. With the bearings greased isn't the important thing that the upper bearings retain the needle in the slot between them? I suppose it would increase the wear on the needle if they don't move, but it still shouldn't affect performance.

David: I hear what your saying about keeping it simple. After all that's the flitetest ethos! I wasn't suggesting that "all metal" construction should be adopted as some sort of standard. What I love about this thread is that so many people have tossed their ideas 'in the pot' and hopefully the reader can decide which suits their own skills/tooling.

Greetings from not so cold but soon to be rainy Ireland.
Dave.

 

[jhitesma]

I'm really intrigued about trying to add an arm and some bearings to better constrain the needle to just up/down movement like that tattoo gun Joachim posted....bit more complex but doesn't look like it would be too hard to implement and could greatly reduce the wear on the needle. I'm not in a big rush to try it...but it does look like an idea that has potential.

I've noticed that same thing with bearings spinning from vibrations on my bandsaw. Even when the blade isn't touching them once the motor reaches certain RPM's they start spinning like mad

Just spent the weekend camped in the desert, my daughter got to have her first go at drowning worms while her friends fished (i.e. they caught something she didn't) for a 6 year old with minimal patience I was surprised at how well she did. Even more surprising not catching anything has her wanting to go again instead of being frustrated! This could be fun. My wife likes fishing and while I'm not crazy about it I do enjoy the occasional morning or afternoon with a line in the water. Had put off trying since licenses are $35 a year here but kids under 10 are free and the other people we camped with had their licenses. So looks like I'll have to break down and get one now.

Back on topic...this morning I woke to a pile of emails about comments on my instructables post: http://www.instructables.com/id/CNC-Needle-Cutter/ Apparently it was picked for this weeks email annoncement! Getting a ton of great feedback from people who are really impressed with the needle cutter idea. And the views on my entry went from ~5,000 yesterday to currently >16,000 and climbing! Wonder if it was enough to get me enough votes to make it to final judging...today's the last day for open voting so we'll see. Fingers crossed. The 3D printing contest it's in still has a few more days...but it's the CNC contest I'm more excited about.

You guys may enjoy checkout out some of the comments there. Some interesting ideas as well as a few of the common questions that have come up here. Maybe I should add a FAQ page to the instructable. And with experience from the Instructable maybe it's time to finally write up a FT article for the main site....Hmm....

 

[dkj4linux]

I wonder if it matters too much. With the bearings greased isn't the important thing that the upper bearings retain the needle in the slot between them? I suppose it would increase the wear on the needle if they don't move, but it still shouldn't affect performance.

David: I hear what your saying about keeping it simple. After all that's the flitetest ethos! I wasn't suggesting that "all metal" construction should be adopted as some sort of standard. What I love about this thread is that so many people have tossed their ideas 'in the pot' and hopefully the reader can decide which suits their own skills/tooling.

Greetings from not so cold but soon to be rainy Ireland.
Dave.

Dave,

I knew that you weren't suggesting all-metal construction for everybody. For you, and others with a workshop, tools, and the skills to use them, it makes total sense to make them of metal or wood... it is, after all, a pretty simple build. My original cutters were also made of metal and wood, I never had friction-heat problems, and I rarely had needles break... and they worked quite well for my need. I was just explaining the philosophy behind why I intentionally resisted recommending that for the masses that I was trying to reach when I introduced it out on the RC forums... I tried to picture myself, an RC/CNC/3dprinter enthusiast, living in an apartment without a workshop or any tools except a few hand tools, a power-drill, and maybe a Dremel/rotary tool. How could I build this thing and start machine cutting my planes?

I, too, like to "brainstorm" so I'm just thinking out loud here...

Adding grease to the mix improves things if the bearings are sometimes just a rounded surface against which the needle is rubbing... and anytime they rotate a bit just presents a fresh bearing surface. But I question then whether they are really adding that much "improvement" to the whole of the cutter. I believe raising the motor and shaft enough to lessen the severity of needle entry angle into the top of the needle guide (effectively "softening" the surface they rub against) has the same effect of reducing friction and increasing needle life... and without the extra bearings. In my experience with the original design, needle breakage has never been much of a problem (I use conservative feed/speed) and it's been "good enough" that I never felt it worth the effort to try to improve on it. But others, such as yourself and Joachim, do... so I'll be happy to sit back and gain from your experience(s) as you do so.

PLEASE, please don't take what I've said as an attempt to talk you out of trying to improve the cutter... it can be improved. So please do try... and then we all gain when you share your experiences. That's what this forum is all about IMO -- David

 

[jhitesma]

Finally remembered to snap a shot of my air tests:



From left to right:

Out of focus - forgot to adjust for thickness of material
Plain - Laser with shroud removed - just the fan above the laser blowing through the heatsink
shroud - Laser with shroud in place
Shroud w/ tape - shroud in place with back side taped up
blowing - me blowing air across the burn point as it burned.

Honestly...they all look the same to me. I can try it with some higher pressure air...but I'm thinking the 40mm fan blowing over the diode is already doing as much good as anything else will.

 

[GremlinRC]

I'm thinking the 40mm fan blowing over the diode is already doing as much good as anything else will.

Well then let me convince you otherwise

You see when I'm talking about air pressure, I'm not talking about what you can get from the 40mm fan. I'm talking about a high pressure air jet directed at the cut point.



Here's a close up of the business end. I found a 3mm tube which I squished at the end to make the exit smaller and to increase the pressure of the air. It's just hooked up to my airbrush compressor, nothing special.


...and here is the result and I think it speaks for itself. I think it answers David's earlier question about whether the 10mm cone from the hood is enough. Clearly no. In fact you could argue that it makes the staining worse. I also forgot to photograph the underside, but the one with no shroud at all did not cut fully through.

3passes 700mm/sec, 100%, 3mm ply.


Cheers

Dave.

 

[dkj4linux]

Well then let me convince you otherwise

You see when I'm talking about air pressure, I'm not talking about what you can get from the 40mm fan. I'm talking about a high pressure air jet directed at the cut point.

View attachment 80031

Here's a close up of the business end. I found a 3mm tube which I squished at the end to make the exit smaller and to increase the pressure of the air. It's just hooked up to my airbrush compressor, nothing special.

View attachment 80032
...and here is the result and I think it speaks for itself. I think it answers David's earlier question about whether the 10mm cone from the hood is enough. Clearly no. In fact you could argue that it makes the staining worse. I also forgot to photograph the underside, but the one with no shroud at all did not cut fully through.

3passes 700mm/sec, 100%, 3mm ply.
View attachment 80033

Cheers

Dave.

Well, Dave, I'm glad you jumped in when you did... I was just about to give a big "Amen" to Jason's assertion, "..I'm thinking the 40mm fan blowing over the diode is already doing as much good as anything else will."

That's a pretty dramatic difference you've shown... so I guess I'll need to look into setting something up. What pressure did you use with the airbrush compressor? Also, with multiple passes are you lowering the focus for each pass? For some reason, I seem to get cleaner cuts with 5 passes in 4.5mm plywood when I simply leave the focus at the top of the material -- David

 

[RAGII]

Got my laser diode a few weeks ago and today my driver board showed up. The name on the back was covered up with what looked like white out. I scraped it off and found it was a Good Laser A-11. I have everything for a test load so I am hoping I can get this dialed in over the next few nights. Now just need my heat sink and I can start playing.

 

[RAGII]

Quick question. I just realized I do not have the female connector for the connections. Where did you guys get them from. I do not really need a large quantity of them which appears all that Amazon carries. Digi Key has some, but I can't find where they list the wire gauge.

 

[jhitesma]

RAGII - I happened to have a fan with the right connector on it so I just stole that...for the laser. The power I'm using the coaxial input right now, and the TTL I unsoldered the connector and hardwired it - but will be putting the connector back on since I ordered a pack of pigtails off Amazon for like $7 or so

As for the air...I'm still looking to get that kind of improvement. Just sort of working up to it. I was surprised I didn't see any changes with the shroud and without which was why I tried blowing. It's been a few years but I was a trumpet player for quite some time so have pretty good breath control - though my embouchure isn't what it used to be I can still direct a blast of air pretty well...I impressed my daughter at her last birthday by blowing out a candle from over 3 feet away So when that didn't make any difference and my cuts still look unstained I started thinking maybe I'm already getting enough air....

But I'll give it another try. But won't be able to try with my air compressor until sometime next week since my wife is working late nights all week this week and we've got plans this weekend that will keep me out of the shop. I might be able to try a fish pump...but I'd rather go big with as much air as I can get for the next test and then work backwards to see where the difference stops. Assuming I can get further improvement.

I notice your cones are pretty far off the material. My shroud sits just barely above the target, maybe 0.032" or so. Maybe that makes a difference...but since I saw no difference with vs. without the shroud I'm tempted to discount that theory.

But hey, I enjoy experimenting Just wish I had more time to do more of it. This really makes me want to build a second smaller machine because the laser is quiet enough I could use it inside at night. I already have an exhaust fan in my laundry room from when I had a darkroom setup in there. Just need to add a bit of ducting to it...hmmm. I suppose if I luck out and win that instructables contest and get one of those XXL shapeoko's I could use it for cutting foam and rebuild the MPCNC as a small inside machine. Would be fun to have a portable MPCNC agian so I could take it places and show it off.