My new CNC
Brian Carpenter
Posts: 728
I will get a picture to post here in the near future. I just to receipt of a probotix comet on friday. the machine is beautiful. it comes complete with an Umbutu computer, monitor, keyboard, mouse, joystick, power supply and Numeric controller. I am very excited to figure out what projects i will build next
Comments
Looks like this uses a Porter Cable router. One problem I had on my first ShopBot was figuring out how to put different drill sizes into the router. I found a quick-change tool post with a straight shank to fit into the Porter Cable router and I still have it if you want me to send it to you. The only problem is that any spindle runout gets amplified when the drill bit is so far from the bearing surface.
I also want to know what you're going to cut on the CNC.
Do you have ear protection? You are going to need it. I'd spend the money on some Bose noise cancellation headphones because that high-pitch screech is like riding a jet engine.
Or are you planning on milling metal? Coolant won't be practical in this case, but maybe it is.
Tell us more, Brian!
Ken Gracey
Has amazing rapids at 250 IPM. That's about half of our Haas SR-100 except you're using steppers. That's pretty darned quick for steppers!
The real elephant in the room about anything CNC is the CAD/CAM software. It's always another expense nobody anticipates. I'm curious what you're doing in that regard.
Ken Gracey
So Brian, how do you like your Comet?
I'm debating with myself over getting one.
I love this thing. I have 'attempted' to build cnc's in the past. i have tried hobby cnc plans. Accuracy was not in my realm of fabrication abilities.
This comes completely assembled and tested. Complete with a pc to run it. I wish i could show you all some great robotic or electronic projects created with this machine. The truth is that i havent had time yet to enjoy those parts.
With the holiday season, i have been creating many projects to sell.
The JOY was cut from 1.25 inch thick Pine Cuts very nice. The letters are cut from MDF. That stuff cuts like butter and i can use a nice higher speed over the pine.
The picture at the far left was done tonight. It is parts for some snow skis for my RC plane.
More pics to come
Pictures from left to right
Ornament in Black Walnut with 90 degree v-carve bit
Small ornament size picture frames for the tree
Pocket routing on the back of a frame
Round picture frame
Nativity set out of MDF
the last picture is to show the dust shoe that i printed on the 3d printer at work It works very nicely
this is an award that i am fabricating. It is in the shape of a puzzle piece. It is 3/8 cast acrylic. V carve the logo and the text.
2 flute .25" upcut bit for the profile.
all the pieces fit together nicely.
The dust shoe is very impressive. Have you thought about selling them? Is that the Bosch router?
I'm waffling between the V90 and the Comet. What sealed the deal for you?
Thank you.
There is a definite difference between the V90 and the Comet.
First off is the the work envelope.
Second, the comet comes complete (pc, driver, power supply, controller tether). the V90 is a kit that you assemble and them add controller and PC
I was tired of building CNC's and not building the things i wanted to build so i went with the Comet. The price was steep for my wallet at first blush but after i received it a have been using it, i am very happy. Jeremy at Probotix hit it out of the park on this product.
Complete with Grease zerks for the slides. 2 steppers (either side of the table) on the Y axis (long axis) for accuracy across the entire x range.
I am using the bosch Colt Router. I purchased the 1/4" and 1/8" collets for it from Precise Bits.
I am sure you will be happy with either.
Users on the Probotix forums don't seem to have many issues with the Comet, and that's a very good thing.
I had no idea you had a CNC, Ken! Steppers can be quick if they're in a rack & pinion machine instead of using lead screws. Mine rapids at 1000 ipm, and it's still possible to get backlash of less than 0.002 with that setup. Mine isn't that accurate, but it's plenty for what I use it for. I have a couple different pieces of software - VCarve Pro being the workhorse, but I also use MeshCam when I need 3d stuff.
The Comet looks really cool, and having a machine arrive ready to run is kind of a big deal - there's a big learning curve in CNC, and trying to figure out if your mistake is in the machine itself or the job you just messed up is a pain. It looks like it's pretty beefy, too - Dual drive screws, supported rails, and aluminum plate is a pretty serious machine.
Congrats on the new machine, Brian! I'm curious to hear what software you use as well.
I too use the VCarve Pro. The software is amazing. I purchased meshcam when i bought the cnc but have not even installed it.
I enjoy the ease of how the Vectric software works. I love the 3d tabing and use it often. As i mentioned to Ken the other day on the phone, I have gotten creative with how to hod down my MDF parts.
On the nativity parts that i cut, i used a 1/4 2 flute spiral down cut bit. It puts the spoils back in the curf and holds the part in place. I am sure this is not the way it was intended, but it works nice.
The Vcarve Pro has paid for itsself in the first 2 months of ownership.
I also own o copy of Cut3D and have only just dabbled as i am not proficient in 3d design yet. But someday soon.
For cutting thin stuff I've recently started cutting mounting holes as part of the design. I drill those first, then use screws through those into a sacrificial board to hold it down, and just clamp the sacrificial board down. Because the screw holes are arranged in the CAM software, I know I'll never crash a bit into them.
I haven't played with downcut bits much, but I just got a few of them. Do you have to ramp into the parts, or do they work well just doing a straight plunge? I used a downcut bit to cut the inlays and inlay pockets for a pick box for my dad, but that's the first time I ever used one. (A pic: http://www.facebook.com/photo.php?fbid=10150468995208973&l=15ce29e2c4)
no ramping on the plunge
The CNC machine itself needs software to parse and act upon g-code. I've seen machines using EMC2 or code borrowed from the reprap project to do this. I haven't seen any propeller based solutions which is too bad, although I know there's one in the planning stages.
However, you also need design software on the PC which emits g-code. I've seen software like simple CNC which can only do simple objects, but seems effective within those constrains. But what else is used?
I've also seen the Mantis and Easy Mill CNC's route PCB's, but it's not clear what software generated the g-code.
Also, how does the design program couple with the g-code interpreter?
The GCode interpreter is given a bunch of information about the setup of your machine, including how many motor steps it takes to move an inch, which axis are controlled by which motors, maximum speed and acceleration per axis, and so on. It interprets the GCode commands which represent things in unit measurements, converts everything into "steps", and plans the motion based on coordinated movement between the multiple axis of the machine, given the speed and acceleration constraints you've told it. It's actually pretty complicated to support the full spec.
A lot of the PCB milling software can generate GCode directly, as it can be very simple if all you're using are the basic moveto / goto commands. I wrote a program that generates halftone images with the CNC, and it outputs GCode directly: http://jasondorie.com/page_cnc.html
For design software, check out Vectric - They have a line of programs that work really well for 2D stuff. I started with Cut2D and upgraded to VCarve Pro, and it was money well spent. I hope to get Aspire one day, but I can't justify the price just yet.