Cutting foam sheets... with a needle!

Headbang

Master member
Looks good! Is this the 15k RPM version?
This motor will only do 12k, in reality aprox 10500rpm. Already working on another sleeve crank for a 2205 2300kv motor. Thought of a better way to do the crank bearing that will be more stable and spread the bearing load over a few bearings. That will be in the next version. But for loading up the jeep. It is Timber Tuesday!
 

Headbang

Master member
So need to make a more stable bearing setup on the sleeve crank. I am also going to have to put in some guides half way up the needle to stabilize it at high rpm. Had it up at 10k rpm, so much more quiet and stable then the clothes pin crank. Cut out a sheet (ft edge wing). Mig tip was cold to the touch all the way though the cut.
20191001_180748.jpg 20191001_180830.jpg
 

Michael9865

Elite member
So need to make a more stable bearing setup on the sleeve crank. I am also going to have to put in some guides half way up the needle to stabilize it at high rpm. Had it up at 10k rpm, so much more quiet and stable then the clothes pin crank. Cut out a sheet (ft edge wing). Mig tip was cold to the touch all the way though the cut.

Wow! Congratulations!
 

Kratho

New member
I would like to thank everyone who shared files and knowledge with me on my road to making a needle cutter. Especially Keno for posting raw files! And DKJ4Linux for creating and keeping this thread alive!

I have combined many files and ideas originated and mixed by others to create my best attempt at an awesome needle cutter!

I ran it at the motors max speed (13,422 RPM) for 30 minutes and was able to hold my finger on the mig tip as it and the heat sync remained cool to the touch.

Hopefully once I balance the motor and pump in 12 volts vs 11.1 off of battery power the motor will get above 14,000.

Thanks again!!
 

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Headbang

Master member
I would like to thank everyone who shared files and knowledge with me on my road to making a needle cutter. Especially Keno for posting raw files! And DKJ4Linux for creating and keeping this thread alive!

I have combined many files and ideas originated and mixed by others to create my best attempt at an awesome needle cutter!

I ran it at the motors max speed (13,422 RPM) for 30 minutes and was able to hold my finger on the mig tip as it and the heat sync remained cool to the touch.

Hopefully once I balance the motor and pump in 12 volts vs 11.1 off of battery power the motor will get above 14,000.

Thanks again!!
That is awesome! The fan may be a bit overkill but heck, why not! The heat will not happen until you start using it, it builds up as the needle drags while cutting. But based on my experience you will have no issues. I like big fat bearings! Bearing size is my down fall right now.
 

Keno

Well-known member
So need to make a more stable bearing setup on the sleeve crank. I am also going to have to put in some guides half way up the needle to stabilize it at high rpm. Had it up at 10k rpm, so much more quiet and stable then the clothes pin crank. Cut out a sheet (ft edge wing). Mig tip was cold to the touch all the way though the cut.
/QUOTE]
I think you nailed this one, thank you for your work. Are we going to see this on thingiverse?
 

dkj4linux

Elite member
When I was a kid in 1950-ish, television was a pretty brand-new thing... small circular screen, b/w, etc. Howdy Doody, which I watched almost religiously, was probably my favorite show... but "westerns" were also one of the most popular early-on program genres. And westerns (at least the ones without any Indians...) were most often the good guys in white chasing the bad guys in black, who ran in outlaw gangs and had just robbed a bank... and always had a surprisingly nice-looking hideout deep in the woods and/or in a remote box canyon somewhere. And, oddly for a small kid, I often thought those hideouts looked like they would be a really neat place to live...

Well, here's my new hideout... and this weekend (with the help of my kids) I'm making a run for it!

20190802_112442.jpg


20190802_112339.jpg


If I don't get caught and hung, or mortally wounded, I'll see ya later ;)

-- David

PS: The kids are headed this way today. We'll pack me up over the next couple of days... and hopefully make our break on Saturday or Sunday. I hope to sneak a peek now and then to try to keep up... you guys are a moving target and doing great! Thank you all!
 
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Headbang

Master member
So I have lost track of how many sleeve cranks I have printed. In the end I have landed on 2 3x7x3 ceramic bearings, and a 3mm x 16mm bolt as a shaft. This seems to be working stably. No heat build up in the shaft. Ran it at 10800rpm today for 2hrs. Only thing it needed was a drop of oil in the cotton oil well after the first hour. Installed and cut 2 sheets tonight. Very much an improvement over the clothes pin crank. Time will tell tho how robust it is. Now on to the next one with a 2205 2300kv motor.
 

Kratho

New member
So I have lost track of how many sleeve cranks I have printed. In the end I have landed on 2 3x7x3 ceramic bearings, and a 3mm x 16mm bolt as a shaft. This seems to be working stably. No heat build up in the shaft. Ran it at 10800rpm today for 2hrs. Only thing it needed was a drop of oil in the cotton oil well after the first hour. Installed and cut 2 sheets tonight. Very much an improvement over the clothes pin crank. Time will tell tho how robust it is. Now on to the next one with a 2205 2300kv motor.
What oil are you using?
 

Springer

Member
Well. . . Had my first serious crash with my cutter this afternoon. As one might expect I had a flying buddy over and we were cutting a lead feather Yak 55 for indoor this winter and showing off the machine. I had been using the laser for a couple weeks, so had to swap the needler in. Got that done, set up vac table, zeroed everything. Powered it up and got half way through the kit when it started vibrating bad, motor popped off mount, needle and bearing assembly went flying! Chaos! My setup is same as David's, using an emax 2812 motor and his press-on flywheel, which has worked perfectly for more than a half dozen 24x48" sheets of MPF. The needle seemed to have survived ok, so I put everything back together with fresh locktite on grub screws and started again, only to have it come off again in perhaps a minute of running. Twice! Our current root cause diagnosis is that the emax grub screws are 180 degrees apart, and I set it up so they are on a horizontal line, which allows the vertical loading to flex and loosen the screws. (How it managed to go for many sheets, then loosen almost instantly, I don't know). As an attempted fix, I drilled and tapped two 3mm holes so they and one original one form an equilateral triangle. Assembled it with a new needle, locktite, etc. Letting it sit overnight. Will test tomorrow. Have any of you guys had this kind of failure?
 

Headbang

Master member
Well. . . Had my first serious crash with my cutter this afternoon. As one might expect I had a flying buddy over and we were cutting a lead feather Yak 55 for indoor this winter and showing off the machine. I had been using the laser for a couple weeks, so had to swap the needler in. Got that done, set up vac table, zeroed everything. Powered it up and got half way through the kit when it started vibrating bad, motor popped off mount, needle and bearing assembly went flying! Chaos! My setup is same as David's, using an emax 2812 motor and his press-on flywheel, which has worked perfectly for more than a half dozen 24x48" sheets of MPF. The needle seemed to have survived ok, so I put everything back together with fresh locktite on grub screws and started again, only to have it come off again in perhaps a minute of running. Twice! Our current root cause diagnosis is that the emax grub screws are 180 degrees apart, and I set it up so they are on a horizontal line, which allows the vertical loading to flex and loosen the screws. (How it managed to go for many sheets, then loosen almost instantly, I don't know). As an attempted fix, I drilled and tapped two 3mm holes so they and one original one form an equilateral triangle. Assembled it with a new needle, locktite, etc. Letting it sit overnight. Will test tomorrow. Have any of you guys had this kind of failure?
Vibration is a killer! Spending a lot of time adjusting a balance screw to make things as smooth as possible helps a lot. I think I spent over an hour adjusting one way until it got smooth then got worse then adjusted back to smooth. I did this on the bench so I could really see and feel vibration easy.
 

dkj4linux

Elite member
Mike,

I haven't had anything so severe as that. However, I've never trusted those little grub screws on that motor... and have always replaced them with short 3mm screws that I can torque down on a bit more. Then again, I've not done the serious cutting that most of you guys have. Of course, we've now had several different slip-on flywheels, fitted on different motors, with different mounts... so maybe you'll want to pick a motor with a more secure mounting scheme?

-- David