Cutting foam sheets... with a needle!

[dkj4linux]

Verris, those are outstanding looking cuts... I'm anxious to see the finished plane now. I also want to check out your firmware and hook-up mods for controlling the ESC... I really like the way you ramp the motor up to speed. If I understand correctly, you are picking up "battery" power from the D9 fan output... and the PWM control signal from the Servo 0 output? -- David

 

[Verris]

Verris, those are outstanding looking cuts... I'm anxious to see the finished plane now. I also want to check out your firmware and hook-up mods for controlling the ESC... I really like the way you ramp the motor up to speed. If I understand correctly, you are picking up "battery" power from the D9 fan output... and the PWM control signal from the Servo 0 output? -- David

That's correct. The battery leads on the esc plug directly into D9 (5mil bullet connectors plug nicely onto the contacts inside an xt60) and since it's powered by the same source as the ramps, you don't need the 5x and ground from the servo header so a single wire run from the signal pin on servo 0 port is all you need.

The only firmware change needed is to change the number of servos from 0 to 1 in configuration.h.

 

[jhitesma]

Now you've got me wanting to find the right speed setting on my ESC and go back to using that servo wire I put in but haven't been using

Did you get a laser? Will make doing the posterboard bits easy Needle can do them but I much prefer the laser for those.

 

[Verris]

No laser yet, but it's definitely on my list. People seem to be using banggood lasers, any suggestion for a specific one?

 

[Verris]

I see this one is on sale right now, how would it work? I really know nothing about using lasers aside from needing some quality eye protection.

http://www.banggood.com/450nm-3500m...r-Cutter-Engraver-p-1103261.html?rmmds=search

Edit: looks like its out of stock right now, but hopefully when its back in stock it'll be the same price.

 

[RAGII]

Verris,

One of the reasons you might not have been able to auto select the main part is there is likely a small gap in the lines in the drawing. I have found this to be true in many of the FliteTest pdf plans. They are usually where two arcs join up or where an arc meets a straight line. I am lucky enough to have AutoCad so I convert the pdf files to AutoCad and then clean-up the drawing and search for these gaps and correct them.

 

[Verris]

I think it might have been because I turned the layer visibility off then back on which locks the layer.

 

[x33]

... now that everybody is off 3d printing planes
......
.......and have never had issues with loss of sync or missing steps. -- David

Yes...I've seen some of this printed "heavy monsters" and I'm not realy convinced!
---> a Flying Wing Design (Span = 0,9m ) with a mass just below 1000g....glued together form 100 parts....a printing time of 100 days...but it will not last 100min in the hot summer sun...

............
Thanxs for the infos on the steppers...I'm a little anxious when working two Nema 23 (3A@35V) on two sturdy ballnut-screws in parallel for one axis...but a sycronized version is toooooo expensive...so I will have a try...

 

[Verris]

Just a note, I'm using my steppers in series as per his newest instructions. I had two different sizes of steppers and even the minimum he suggests (42oz/in) works fine for my y axis and z. No problems there at all. Running my stepper drivers at 90% of the motor max (Max is 1a).

 

[jhitesma]

Yes...I've seen some of this printed "heavy monsters" and I'm not realy convinced!
---> a Flying Wing Design (Span = 0,9m ) with a mass just below 1000g....glued together form 100 parts....a printing time of 100 days...but it will not last 100min in the hot summer sun...

Well, I had to give it a try:



Without battery it came in at about 375g...but I still had a few small bits to add so it's probably closer to 400g. Pack I'm running is about 150g, so 550g ready to fly for what's close to a 1m wing...I'm pretty happy with.

It was 40 hours of printing...but just the corner blocks for my MPCNC took that long. It's about 10 parts - could be fewer if you have a bigger printer. The designer crashed his quite a bit and never managed to break a part just glue joints. So we'll see.

Now - leaving a PLA printed plane in my car in the summer is indeed asking for trouble here in the desert. I'd like to try PETG but I'm not sure it would be strong enough. And I just got some "Raptor Series" PLA from Maker Geeks that you can anneal and is dishwasher safe claimed to not warp at up to 250F after annealing. So if I like the way it flies I'll be tweaking it to accommodate some FPV gear and reprinting with the raptor

 

[x33]

....550g ready to fly for what's close to a 1m wing...

....not warp at up to 250F after annealing....

The model looks fine...landing speed with this weight may be a little high???
The conversion for 250F is ~120°C - sounds like a big improvement compared to normal PLA


This technology
https://markforged.com/mark-two/#specifications
could be a great advantage in printing lightweight and strong parts....
"....the Mark Two prints materials that no other 3D printer can, like Carbon Fiber, Fiberglass and Kevlar...."

ooops...the price is not so "lightweighted" ---> $13,499.00

 

[Verris]

Laser parts are on the way on the slow boat, thanks to Jason's advice.

 

[Verris]

Video of the first full sheet cut!

https://www.youtube.com/watch?v=c1JVG0g0JHw

It worked pretty well, my z ended up off a little bit so there were still some bits holding it together on the bottom, but I ran through it with an xacto and in a couple minutes it was perfectly fine.






Then while printing the second wing, disaster struck and the needle guide ended up in the foam, the needle was gone and that foamboard sheet was done for.



So this is related to two things, one, that my stepper motors get very hot, especially my smaller set. So hot that I just added heatsinks to them. And two, that my pineapple coupler never fit my threaded rod very well. It was mostly held together with super glue.

I'm printing a new smaller pinapple coupler, the imperial version is slightly smaller than the 8mm version, but my 8mm rod fit too loosely in the 8mm coupler, so I'm printing the imperial one. While I'm at it, I'll lengthen my threaded rod as I ended up lengthening my z axis earlier but the rod is still shorter so it eventually comes out. Also, while I have it apart, I'll be adding some lithium grease to the z axis to hopefully smooth it out a bit.

 

[dkj4linux]

Video of the first full sheet cut!

https://www.youtube.com/watch?v=c1JVG0g0JHw

It worked pretty well, my z ended up off a little bit so there were still some bits holding it together on the bottom, but I ran through it with an xacto and in a couple minutes it was perfectly fine.
...
So this is related to two things, one, that my stepper motors get very hot, especially my smaller set. So hot that I just added heatsinks to them. And two, that my pineapple coupler never fit my threaded rod very well. It was mostly held together with super glue.

I'm printing a new smaller pinapple coupler, the imperial version is slightly smaller than the 8mm version, but my 8mm rod fit too loosely in the 8mm coupler, so I'm printing the imperial one. While I'm at it, I'll lengthen my threaded rod as I ended up lengthening my z axis earlier but the rod is still shorter so it eventually comes out. Also, while I have it apart, I'll be adding some lithium grease to the z axis to hopefully smooth it out a bit.

Oh, my! Things looked great up to the point it failed. Did the Z-axis actually fall suddenly in mid-cut?

It's interesting that you have different steppers on the X and Y axis... just used what you had on hand? Also have you checked your motor driver reference voltages... motors running so hot it's probably set too high for those particular steppers? IIRC 0.75v for X/Y, 0.5v for Z are reasonable starting points for steppers with same/similar ratings commonly used for MPCNC.

Sounds like you have it all under control... please let us know what you find -- David

 

[Verris]

Yeah, my steppers are from my pre-upgrade kit Prusa i3, which had two different sized motors. The voltages are all set to their correct values according to Ryan's directions. My problem was the coupler started slipping around the threaded rod, only sometimes gripping it so when it would spin there was a chance it didn't move, which it didn't move up, then it did move down and went past the bottom. I've got a new coupler printed, attached with better screws I could tighten more and actually designed and printed a new cutter mount overnight that I'm about to assemble and see how it works.

 

[Verris]

The first new version worked ok, it was mostly a combined version of the add on bearing block, added 20mm height and Jason's cutter. The needle would slip forward and back and ride between the bearings and the wall, or the bearings and the restraint out front.



I've now printed this beautiful contraption to test all the fits and it works great. Next step is to attach it to the cutter and print it out.

 

[Verris]

Also, another huge upgrade was changing from the 5 for $0.80 inflation needles to some that came with a pump by Spalding. Their walls are about twice as thick, they are longer and they are attached at the top a lot better. The pin fell out of the first one I was using.

 

[jhitesma]

I actually was going to comment on the Spalding needles. Because apparently my walmart has switched from the cheap generics they had before to Spalding. Same price or at least still in the 2 for $1 range. But as Verris says they're thicker and more substantial. It does seem to run with a bit more friction for me, but I doubt I'll wear it out nearly as quickly as the last two cheapies!

 

[Verris]

Now cutting the piece that previously it failed on. Working great with the new cutter.

https://www.youtube.com/watch?v=zi6u0tOCkMw

 

[Verris]

New cutter works great, though Jason was right, cutting posterboard leaves a lot to be desired. Laser will be here eventually!

Finished building the spitfire. Everything lined up perfectly except one tab cut on the original version where a corner got messed up. Seems to be fixed with the new version.

I printed out a set of Tiny Trainer plans because I've built so many by hand I'd like to compare it to the handmade ones. The first sheet I set my needle a little too low and apparently my bed is a bit out of level because when it got to the back corner, the guide got under the foam and bent. Straightened it out and moved the needle up a bit more for the next sheet and it cut perfectly. No issues on the replacement sheet or the second sheet.

My current problem is that after about 6 sheets of cutting, my clothespin is worn down into a groove about 60% of the way through so it won't last much longer. Finding a spring the right size for the shaft wasn't the easiest, finding one the right size and a stronger metal is going to be tough. I might see if I can bend my own spring out of thicker music wire.