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Cutting foam sheets... with a needle!

That looks pretty cool David. Yes PTFE will definitely finish that off nicely. Just wondering how much infill you use on these printed cutters? I will probably have a go at making my own version too. I may well try Basscor's idea of the 4 bearings to keep the needle totally straight. Took delivery of a big stash of piano wire today so got lots to play with:)
Thanks, Dave. I use 30% infill, 3 perimeters, and 3 top/bottom layers. Jason's parametric needle cutter (http://www.thingiverse.com/thing:1723915) will give a basic cutter body -- I increased the "back height" to 50 mm -- and then added the sideboard mount in Tinkercad. -- David
 
the postman...

...was at my house!
----------------------------
Hi, I can see a lot of nice 3D-Printings :) but I will be out of business in making new needle cutters the next time!

---> The postman gave me a heavy package with some fine goods to play with ;)

rails-01.JPG

rails-02.jpg

rails-03.jpg

I want to have a router at home...this is more convenient than sitting in a factory-like compartment...especially for longer test (laser)

For the first step, I ordered 2 sets of SBR-rails 16mm (gantry) + 20mm(main)
Because this rails are supported over the whole lenght, they can be mounted very easily.(I hope so..;))

I will build the main body from multplex/plywood (18mm).
This frame will make it strong enough to do some real milling jobs...but first, I will use it for the laser and the needle cutter.
The rails are 80cm long...with a real toolpath space from ~65x~65cm - which is big enough for most jobs (I can use my friend's router for bigger parts)

The next step is to look for the right stepper motors and the drive train (may be the timing belt version?) -
By building a kind of a "modular system" I can change this to a more powerfull set of lead screws in the future.
(BTW "BallNuts" is a funny word)

????? Which kind of steppers are you using in the MPCNC???? - I'm looking for Nema23...should be strong enough.

Joachim
 
Joachim. I'm using those exact same rails on my "all metal" CNC and they are great. Nema23 is perfect. I highly recommend that you look at ballnuts if it fits your budget. (yes it is a funny word!). You can of course go with a belt drive but with those fully supported rails you can build a machine capable of milling aluminium and you won't get that strength with timing belt. Avoid ACME leadscrew if you can, it will severely limit your max speed (unless you get a very big thread pitch which will then eat into your accuracy.

Good luck,

Dave.
 
1> I'm using those exact same rails on my "all metal" CNC and they are great.
2> I highly recommend that you look at ballnuts if it fits your budget.
3> You can of course go with a belt drive...
4> Avoid ACME leadscrew if you can....
Dave.
Hi Dave, thanx for the infos!
1--> yes, they look strong, but mine where a little bit bend like "bananas" ;)...could fix this very easy by releasing the scews a little and tighten them again.

2--> I will look for the balls, ä...nuts, ähhh...BallNuts :)...I do not know if I will use one in the center or two (one on every side, coupled with a beltdrive)
?Any idea for the pitch?

3--> my intention is to use the belt for the first tests using 2 belts/motors for the main axis and a system like that
http://www.buildyourtools.com/phpBB3/viewtopic.php?t=1050&p=3221
for the gantry ...Can switch over to the lead screw after some time.

4--> I never had them in my mind...only 2 solutions -> beltdrive or ballscrews

I do not want to spoil this "needle-thread" with to many post about the router, but I will send some building infos now and then.

Greetings from Germany
Joachim
 

jhitesma

Some guy in the desert
Mentor
Thanks, Dave. I use 30% infill, 3 perimeters, and 3 top/bottom layers. Jason's parametric needle cutter (http://www.thingiverse.com/thing:1723915) will give a basic cutter body -- I increased the "back height" to 50 mm -- and then added the sideboard mount in Tinkercad. -- David
That's about what I do...but I usually only use 15-20% infill. The extra perimeters seem to give more strength than infill in my experience so I mostly use just enough infill to support the top surfaces well.

I'm thinking about modifying the defaults on the Thingiverse listing with more default height since it seems that's the way more and more things are moving :) But I also still want to add some guide supports - just debating how I want to do it. I'm thinking about just two towers with four mounting holes - so they can be used to mount bearings or wood blocks. But debating how configurable they need to be.
 
That's about what I do...but I usually only use 15-20% infill. The extra perimeters seem to give more strength than infill in my experience so I mostly use just enough infill to support the top surfaces well.

I'm thinking about modifying the defaults on the Thingiverse listing with more default height since it seems that's the way more and more things are moving :) But I also still want to add some guide supports - just debating how I want to do it. I'm thinking about just two towers with four mounting holes - so they can be used to mount bearings or wood blocks. But debating how configurable they need to be.
Sounds good, Jason. I think you are right about the infill... I'm going to default mine to 20% as well.

If/when you do decide to implement the added towers, do you suppose maybe there could be a "single" or "split" tower option... with all the tower dimensions, hole spacings, etc customizable as well? With the apparent ease and rapidity with which you implemented the parametric cutter in the first place, I guess I don't see that as too out of line with all the customization you've already built into that "thing". And it would sure make life easier for all us "dummies" out there to make a mount for almost anything -- bearings and/or sideboards -- that we might want to back/constrain/guide the needle with. Pretty please??? Huh, Jason... pretty please? ;););) -- David
 

jhitesma

Some guy in the desert
Mentor
Main reason I haven't done towers yet is I'm kind of waiting to see how the testing/prototyping works out so far :D

So any input on what kind of options I could/should add are more than welcome and will help make sure I get to it sooner rather than later ;)
 
Main reason I haven't done towers yet is I'm kind of waiting to see how the testing/prototyping works out so far :D

So any input on what kind of options I could/should add are more than welcome and will help make sure I get to it sooner rather than later ;)
I don't think there's any doubt the towers would be a welcome addition. The only thing holding me back from testing what I've got is -- first, I'm lazy and trying to get ready for another fishing weekend-- and the other is that I really haven't got suitable PTFE, Delrin, etc to make proper side-boards with yet. I'm thinking of just greasing the printed ones I made and give them a go... wooden ones might also be used but I'd sure like to laser-cut them and that means I'd have to clear all the crap (a technical term) off my laser setup. I've also thought about possibly using DT plastic cutting board material... I think it's probably HDPE but don't know if it's really any good for this application or not (can it be safely laser-cut?).

-- David
 
Made some great progress this weekend and got everything built and working!

http://imgur.com/a/6AZoe

Some of those are progress pictures and some from when it was almost done. I've got it drawing nicely with a ziptied and taped pen. Had an issue where estlcam was starting a print witt a g00 to 0,0,0 at 2100 speed which was murdering my z axis. Had to change it to start above origin rather than start at origin which used the correct rapid z speed of 350.

Just need to attach the cutter and try it out.
 
Made some great progress this weekend and got everything built and working!

http://imgur.com/a/6AZoe

Some of those are progress pictures and some from when it was almost done. I've got it drawing nicely with a ziptied and taped pen. Had an issue where estlcam was starting a print witt a g00 to 0,0,0 at 2100 speed which was murdering my z axis. Had to change it to start above origin rather than start at origin which used the correct rapid z speed of 350.

Just need to attach the cutter and try it out.
Verris,

That really looks great... nice and clean. I look forward to see some foam cut :D -- David
 
Looking good Verris. I'm impressed by how neat and tidy everything is. That unfortunately is usually last on my list:)
Like David, I'm looking forward to seeing it in action.
Cheers
Dave.
 
It lives!

I've made a few cuts now. First problem I found out was that my quick mount flexed up and down quite a bit, so I had to jam a little flattened aluminium tube into the gap which stiffened it right up.

IMG_20170222_111048.jpg

Then I had to play around with the rpm as I was getting a lot of little holes in the bottom rather than a nice cut. I found around 7600 (While spinning the needle but not cutting) works quite well. I then had to grind off a bit more of my inflation needle as it wasn't flat on the bottom and I figured getting it closer to the paper would be better and a point prohibits that.

I then realized my stroke is just a bit too short only going about 0.5mm into the spoil board so I bent the crank out a bit and now get about 1.5mm into the spoil board which was the biggest increase in performance.

I then added the cotton and oil which cleaned the line up a bit more. And finally, I made a new needle wrapped around a smaller shaft so get less slop where it attaches to the clothespin spring. This helped quite a bit too.

In the end my lines improved quite a bit and the last thing I did for the night was cut a pretty nice looking circle. Oh, then registered EstlCam because the countdown is the perfect level of annoying.

IMG_20170222_010831.jpg
IMG_20170222_010906.jpg

There is a bit more work to do to try and clean up the fuzziness, I might try lowering the feedrate a bit and going back down to 6000rpm. But it looks good, I think.
 
It lives!

I've made a few cuts now. First problem I found out was that my quick mount flexed up and down quite a bit, so I had to jam a little flattened aluminium tube into the gap which stiffened it right up.
...
Then I had to play around with the rpm as I was getting a lot of little holes in the bottom rather than a nice cut. I found around 7600 (While spinning the needle but not cutting) works quite well. I then had to grind off a bit more of my inflation needle as it wasn't flat on the bottom and I figured getting it closer to the paper would be better and a point prohibits that.
...
There is a bit more work to do to try and clean up the fuzziness, I might try lowering the feedrate a bit and going back down to 6000rpm. But it looks good, I think.
Outstanding, Verris! It looks like you are well on your way to cutting planes.

I wouldn't lower the 7600 rpm (free-running) too much. I usually try to set the rpm at a bit more than 7000 rpm (free-running in air)... it will drop 1000 rpm or so when you actually start cutting foam. Since I usually use 600 mm/min for the feed rate, that insures I'll get about 10-11 perforations/mm... which I find gives decent cuts in DTFB.

Also, I couldn't tell from the photo... there are holes in the quick-change mount and receiver that should line up to allow putting in a couple of 3mm screws to lock them together. Or, you could just jam a flattened aluminum wedge in from the top :rolleyes: -- David
 
I've got the screws in the bottom holes, but theres only two levels of holes in the needle mount. It might work better to use the tall mount with all 4 holes. My needle mount seems thinner than the slot in the quickchange mount so it wobbles around in there.
 
Just got the esc controlled with the ramps board.

I have my esc (Some chinese simonk 24A esc) wired to D9 which is the fan control. I then ran a wire (One of my extra from my cat5e cable for my z stepper) from the servo 0 signal line next to the reset button on the ramps board to the signal line on my esc. I then had to go in to the firmware and enable 1 servo control, In the config file just search for servo and change it from 0 to 1.

Next I calibrated the esc

M280 P0 S180 - Set the max pwm to 180
M105 S255 - Power the fan (Esc power) at full
M280 P0 S0 - Set the minimum pwm

I did all these manually in repetier host.

Now to use the motor I just add this so the start of the gcode in estlcam

M280 P0 S0
M106 S255
G4 P2000
M280 P0 S16
G4 P400
M280 P0 S32
G4 P400
M280 P0 S47


And this to end end

G4 P0
M280 P0 S0
M107


** Added the G4 P0 to make sure the cutting is done before turning off the needle. **

I set the pwm to 0, enable the esc power, wait 2 seconds for the esc to power up, then start throttling up the motor in 3 steps with a short delay between each.

At the end, set the pwm back to 0 and turn off the esc.

Your values for the correct pwm will vary, for mine 7500rpm happened to be at 47.
 
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Just cut my first "part", a dihedral gage for the spitfire. So far I'm using adobe acrobat to delete all items from any layer in the plans other than cut, score, reference or crease. This leaves me with only the needed lines. Then following Moebeast's steps of setting the document size in inkscape to 30"x20" and importing the pdf. Ungroup a few times and rearrange. Exporting it then importing to estlcam.

Now to try something more complex with score lines and slots.

IMG_20170222_220156.jpg
 
Few more things after printing my first actual part, make sure to save from inkscape as dfx. Svg works fine for single layers but dfx preserves the layers which makes it really easy to put scores, creases and cuts in three separate levels and turn them off in EstlCam so you can do all of them at once.

It might have been something else, but at first I wasn't able to auto select the full path to cut the main part out, then in inkscape I selected everything and hit Path -> Object to path and resaved. This let me select the entire outside as one cut, the two inner cuts as one each and then used the point to point from the ends of the score line.

Got a vertical stabilizer cut for the spitfire and it seems to be pretty perfect. Ignore the dark spots all over, I put a bit too much oil in the cotton and it started spitting out during the cut.


Front
IMG_20170222_223933.jpg

Back
IMG_20170222_223942.jpg

Removed
IMG_20170222_224035.jpg

Score
IMG_20170222_224054.jpg
 
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Hi...I'm still alive and watching the posts....
.... and it seems to be pretty perfect
.... I put a bit too much oil in the cotton and it started spitting out during the cut.
yeah...that looks quiet nice :) :applause:....It is very hard to cut parts like this with a knife

;) you should watch the cutting a little closer...and you will have these funny looking spots in your face ;)

..........
I did no more cutting since my last post....the postman is dropping in many times with the parts for the router...and I'm trying to put every thing together "in a functional way" ;)...not so easy to build a thing like this from scratch.

Greetings from Germany....Joachim
=====================================
PS
???---> the is MPCNC working with 2 steppers per axis (not syncronized...only 2 parallel power drivers?)...any bad experience with this??? (loosing steps..)
 
Hi...I'm still alive and watching the posts....
...
???---> the is MPCNC working with 2 steppers per axis (not syncronized...only 2 parallel power drivers?)...any bad experience with this??? (loosing steps..)
Joachim,

Good to hear from you! I'm still here, too... but the thread has really slowed now that everybody is off 3d printing planes ;)

The original stock MPCNC uses two NEMA17 steppers on each of the X and Y axis. The two steppers on an axis are wired in parallel... with the exception that one coil is reversed on one motor so that one turns CW and the other CCW. Both steppers are driven by one A4988 or DRV8825 driver... not unlike the Z-axis on many/most 3d-printers out there. The wiring is shown here

https://www.vicious1.com/assembly/wiring-the-steppers/

While many use the MPCNC for heavier stuff like routing/milling... I use it only with light loads -- needle cutters, lasers, etc -- and have never had issues with loss of sync or missing steps. -- David