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DIY CNC Cutter


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Hopefully getting the final tweaking sorted them some serious cutting next month :D.
 
Although its behaved flawlessly the overlimit switches and dremel "off" at the the end of the run should give me peice of mind between coffee  breaks  ...i hope 

Edited By Foamie Dave on 20/04/2009 20:07:22

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Peter, there are a few ways of adjusting the cutting height. Pockets (milled areas) are created by generated using one of the Phlatscript tools in Sketchup, for each area you can define the cutting height as a percentage of the material thickness. Tabs (the pieces that hold the cut parts to the rest of the sheet) can also have a user defined height. There is also a 'Fold' tool that allows you to specify the cut height of individual lines if required. 
 
The Phlatprinter is actually capable of 2.5D cutting (full 3D cutting requires a 4 axis machine so that the material can be rotated). At the moment this is not possible using Sketchup, but below is a photo of a 2.5D cut created using the Phlatprinter :
 
 
Hope this helps,
Si.
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Cheers Si

Peter , This is Wiki's definition if it helps
 
 
 

In machining, 2.5D refers to a surface which is a projection of a plane into 3rd dimension - although the object is 3-dimensional, there are no overhanging elements possible. Objects of this type are often represented as a contour map that gives the height (thickness, depth, etc) of the object at each point.

2.5D objects are often greatly preferred for machining, as it is easy to generate g-code for them in an efficient, often close to optimal fashion, while optimal cutting tool paths for true 3-dimensional objects can be NP-complete, although many algorithms exist.

2.5D objects can be machined on a 3-axis milling machine, and do not require any of the features of a higher-axis machine to produce.

 
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Hi Dave, saw your latest creation on Youtube. Did you use your Phlatprinter for any of the cutting out?
Can you tell me if you got a relay board with your Phlatprinter? I didn't order one and of course it's essential if you're going to switch the cutter on and off.
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Hi Tony,
 
Unfortunately the Phlatprinter arrived just after Id finshed it (presume you mean the Beretta) but Ive started cutting a few bits for a couple of new ones Ive got up my sleeve and theyre coming out a treat.
 
Ive tried cutting a plywood motor mount as well (2mm works great but I it struggles on 4mm and above..lots of charcoal and loud smoke detectors !!) . I think balsa will be walk in the park (Si also sent me a 1.5mm bit to try out)
 
Funnily enough Ill be fitting the relay board later this week . I ordered mine from  Rhonmac-cnc but its very similar to the Easy CNC unit.  At the moment Im just switching the cutter on/ off by a mains rocker switch but ill just wire the relay card output in series so Ive got a manual and auto power off just in case.
 
 
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Hi Peter, remember you must cut or you rub the cutter blunt! So, say .001"/rev
35000x.001" = 350"/m divide by 60, you still get 58"/sec !!! I don't have mine yet so I can't comment, but 1st, I doubt the Dremel is going 35000 under load, and 2nd, the cutter is upside down, so maybe it's not clearing the chips.
To get back to your original statement, yes 1"/sec is very, very  fast if you're used to larger machines and cutters.
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Hi Dave, I see you've fixed your deliberate mistake However, if I may be so bold It might be a good idea to check the rpm of the Dremel under load, then try a feed rate that gives you about .001/rev. I don't know what the hp requirement is for hardish wood, you'll probably find it somewhere, it'll W/cc/min, maybe it's the Dremel that's being overloaded.
Another thing, are you using HSS or Carbide cutters?
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Dave, I just ran a test cut of my motor mount file with a 1.5mm chipbreaker bit (like the one I gave you). I reduced the feedrate to 0.7ipm and it worked pretty well, although it did burn the edges of the ply a little. I taped some 3mm depron to either side of the ply so that the drive roller had more material in contact with it.
 
It's slow going, it took about 20mins to cut this mount, but I don't think I could cut one by hand in the same amount of time.
 
Si.
 

 
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Hi Tony,
 
Im not sure on the bit material I'm afraid . The 3mm came with the Phlatty (no markings) and the 1.5mm came from Si (cheers mate). The dremel must be bogging down a bit under load as you can hear the rpm change quite a bit.
 
Si, what thickness of ply is it ??. Ive just got some more 2mm to play with , but Im still stuggling on 4mm.
 
Just got home (9.30pm)  so hopefully  wiring the relay card up later tonight if I can keep my eyes open  so I  can try some more  test cutting tommorrow. That way I can leave it cutting without worrying the dremel will be left running at the end of the cut.
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Hi Dave, I think I'm going to butt out of this discussion for a while. Without having anything to test on I'm just batting the breeze! One last thing though, when I was young and stupid! We were taught never to use less than 1thou per flute of cutter feed rate, and that is in metal, wood is much softer, so the cutter should be able to easily handle 2thou /rev feed rate. Maybe it's the power of the Dremel that's letting you down.
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Cheers Tony,
 
Its still going to be very much trial and error with me at this stage anyway as Im very much on the bottom rung of the ladder regarding this kinda stuff . Many thanks all the same for your input so far (hugely appreciated).
 
Hope the post office comes good with yours  and let us know when it arrives
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You got that right Peter! I think that's why Mark changed the cutter arangements on the Mark 2. Perhaps upgrading to a Die grinder with a flexi drive on it is the way to go. Rigidity and horsepower! Something else I've just thought of, when you're cutting aluminium you don't go much over 100m/min surface speed, I imagine hard wood is very similar, so 3 x 3.142 35000/1000 = 210m/min I would guess that with harder materials high cutter speed is going to be a problem. Somebody check my math please!
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Hi Dave, I've installed Sketchup 7 to my D: drive and downloaded the Phlatboyz_v0.918. Obviously unzipped and put the files in the right places and rebooted.
When I start Sketchup 7 I don't get the Phlatboyz options in the Menus, I just get the words 'Dynamic components'. Any ideas?
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Hi Tony,
 
Im at work now so cant get acess to my machine but if i remember correctly you have to enable it  before it will show on the options and the buttons appear on the SU interface
 
Launch Sketchup, then on the top option bar, click on
 
Window > preferences > extension > then tick the Phlatboyz Tools  tick box and reboot SU
 
That should do it
 
 
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