That was fast! It was the motors that I used. A friend of mine happened to have 4 stepper motors at work that he gave to me and they don't all match. This made sense at the time to just get started since the store was out of stock. 2 steppers are 0.9 degree steps where the other 2 are 1.8 degree steps. The 2 on my X and Z axis are both 0.9 degree steps so mystery solved. When I doubled the step/mm on the X from 40 to 80 it works like a top and the X is now drawing 100mm lines.

Once I corrected that I layed down a 64 segment circle and drew it. The machine preformed much smoother than last night by a long shot and you can't even tell the circle is segmented by looking at it. However you can hear that it is segmented as the machine is drawing it . There is still that starting and stopping but it is less jerky than before. Not the smooth motion that I would have expected, but in all honesty I wouldn't be able to tell the difference by looking at it so I'm ok with it grunting through circles and arcs a little.

The real funny thing was the curves for the text sounded great when it was drawing those even with wonky settings. The 'O' was a very fluid motion unlike the circle. I'll have to take apart the G-code maybe that can tell me why.

 

I am using the grbl controller version 3.5. I grabbed the source code my version is using and also the 3.51 version to have a look and G64 is not supported unfortunately.

I guess SketchUCam exploded my circle because I didn't see any Rxxx terms in any of the generated gcode of sketchUCam when drawing the circle in sketchup (I did not scale it or use a transform in any way). I do not know how to make a complete arc with sketchup beside just using the circle tool. When you say complete arc I'm assuming you mean a circle. A few questions came to mind as I was writing this:

Is there any sort of tutorial on phlatboyz SketchUCam and what all the buttons do etc? I still don't understand what the majority of controls do, for instance, I still have no idea what a phlatbone is or what it is used for.

I need to learn more about these gcodes. Does anyone know of a good site that explains in detail each one?

David, what controller is your friend using?

 

David, Thanks for all the info will have plenty of reading to do now.

I'm getting ready for my first cut and I will be cutting foam first to test out the gcode and then acrylic. Do you guys have any recommendations for a dremel drill bit that cuts acrylic nicely? Something that doesn't melt it and gum it all up.

The thought never occurred to me until I started planning to cut something real but how are you guys clamping down your work pieces to the bed of your CNC's? There doesn't seem to be any good spots to use a clamp or such.

I had a look at it today, going to hold off on buying software until I know for sure this is something I want to invest a lot into. I don't want to use it quite yet because I'm afraid I will spoil myself with it and not want to go back

 

Acrylic is harder than wood. I use a 2 flute solid carbide 1/4" bit. At first I cut some foam but it sucked. Then I did wood and it looked great. Next I milled my spoilboard flat and that went well. Now I'm milling acrylic and I hold it down with double-sided tape. I'm finding that some belts need tightening, screws need tightening, etc when I cut the acrylic. It isn't melting at 10,000 rpm but it takes a lot of torque to move at the feed rate I'm using (200mm/min).

EDIT: Shortly after writing this I went out to check on my piece and the tape had come loose and the part was ruined. Now I'm drilling holes in the material and screwing it down to the spoil board.

 

Funny, my feedrate is set to 500mm/min(20ipm) and my cut depth is 1mm(0.04in). They suggest 0.003"(0.0762mm). I think my leadscrew pitch is wrong so it was cutting half that amount(0.02in) but that's still way too much, I guess. I did notice it jerking around as the gantry flexed. Maybe I'll fix the leadscrew pitch and try again at a much smaller cut depth.

 

Let me know how that goes for you. I would be very interested in the settings you used for acrylic if your planning on cutting that. I had a look at the chart but I'm sure I have calculated something incorrectly. I was going to make a metric version of that chart that kram posted but some of the math is wonky trying to sort it out now.

 

In case you don't have a network connection attached close to your mill like me, I created a little xls file with Krams info in it. There are 2 sheets one for imperial (Direct copy of sites info) and one for a metric conversions of the imperial chart.

 

It's working with 200mm/min, 20% plunge rate, 0.0762mm cut depth. This is 1/2" plexiglass, so it's probably the "plastic with glass" type listed in the chart. The cuts are wicked clean, edges sharp, and there's a lot smaller chips coming off which can go airbourne.

 

Very nice, thanks for the info. Glad to hear you have had good success with those settings. When the time comes I will use them, hopefully this weekend. I'm still trying to fashion myself a holder for my Dremel tool. I first tried to use zip ties to hold the dremel to cut some leftover MDF to make some brackets to hold it in place. After that failed, I decided just to let the machine draw it and I will cut it out with the dremel. My hands work better than zip ties any day of the week and even in the mornings.

I have the same tool that Forest has and I downloaded his designs. Had to make a slight modification though because my machine is certainly not a standard one. (I went by the parts list ). I ended up with a piece of 20x80 and not 20x40 on the Z to mount the spindle/tool so I took the liberty of modifying your design a little Forest. I also increased the thickness of the holder a little. I was worried about the MDF not holding up so its thicker now. The holder should buy me enough time to make a better one later... I hope. Attaching the skp file as well if anyone needs/wants it.

 

Better brackets just arrived . Anyone cut 3/4 in MDF before? If so what were your settings. Settings on todays cut were the acrylic settings The Dude posted. My god it was slow... 3 hours about. Wife banned me from ever using it in the house again.

 

The cut depth was set to 0.0762mm same as @The Dude suggested for acrylic. Since it was my first real cut wasn't sure what to expect so I set it low. I was also using the same feed settings of 200 mm/min. What is the worst that can happen if I push the machine too fast and or too deep with depth of cuts for the material I am using? I looked in the speeds and feed charts but didn't see anything listed for wood products or MDF.

 

@Chris Allen and @JustinTime Just curious how you guys attached your Cable Drag Chain's to your machines. Is it resting on something? Got any pictures or skp files? Mounted to the side somehow? etc. I snapped a wire loose today, I should have ordered these earlier.

Yep you were right!

 

Thanks @JustinTime gives me a good idea of how I will hook it up to the machine I have here. Thanks for giving me a preview of what I'll be getting myself into. Much appreciated.

 

Just a quick one for anyone mounting a dremel tool. I found a better way to mount it and lock it down super tight. Home Depot or Lowes carries Conduit Pipe Straps 1 1/2 inch clamp worked wonderfully on my machine. http://www.homedepot.com/p/Unbrande...be-EMT-2-Hole-Straps-25-Pack-61615B/202241092 you can get them in a single package of 2. The gantry will break before that tool moves now, its not budging moving anymore.

Keep in mind I have 20x80 where you mount the tool and it works well for me. For those of you using 20x40 take care you may need to construct some sort of adapter plate so it will fit nicely.

Cheers

 

@Ceiling Cat,
Yes, makes sense ... I already got some of these to use when I upgrade my Routy to an Ox ... it is the way recommended for that build. I need to work a bit more on using Routy to accurately machine plates for OX, when I get back home in a few weeks from Beijing. Been recearching best way to build good bet for this set-up ... considering 80/20 10 series so I can use 1/4" bolts, clamps, etc.

 

Haha, yeah with wood try 800mm/min and cut depth of 1mm. Acrylic is "special" like aluminum, brass, etc. You could try 0.5mm for really clean edges. I think I've run pine through mine at 1400mm/min with ratty edges. One time I had the axis reversed and so it plunged the bit into the wood at top speed(1500mm/min) to a depth of about 25cm. Scared the bajeesus out of me but no harm befell my routy.

 

Is 1500mm/min the top speed of routy? Only thing I have tried is around 200 thus far. I want to run it now but machine is down for repairs presently . I burnt up a stepper apparently. Not sure how it happened but one of them on the y axis doesn't even spin anymore, just kind makes high pitch grunting noise. I ordered 4 new Nema 17's all 1.8 degree steps for better holding torque. Not using second hand steppers this time around.

Do any of you leave the plastic on when cutting your acrylic or do you peel it off? I've been peeling it off but wondering if it would help to keep it from getting scratched if I leave it on.

 

My motors stall at anything faster than 1500. It all depends on your controller board+motors.

I don't have plastic on my acrylic but it doesn't matter either way.

 

hey all
kinda new to the whole cnc thing. but have a lot of experience with 3dprinters. i have just finished the build of routy and have a question. am i able to use RAMPS to run this? id really like to use elecronics i have/know. if so how would i o about this.
and finally im having difficulty finding an appropriote router am currently looking at the kress 1050 but think it might be a little heavy.
thanks
mevo

 

3D printers and CNC machines have identical components with the exception of the router/print head. If you can run GCode you can do CNC. The best router, by far, is the 890KV OX spindle plus it costs less than any others. I think you need a drill press to make it.