Posts Tagged ‘CNC’

R3 Initial Electronics Progress

Friday, April 29th, 2011

I haven't gotten much done on the hardware side of things lately, but I've been busy with the electronics of the R3 platform I'm working on.  Above is the first draft of the parallel port adapter that will be used for the first round of machines.  This board allows a PC running Mach3, EMC2, or any other G-Code interpreter with a parallel port driver to control up to 4 RepRap/Makerbot stepper motor drivers and has separate inputs for X, Y, and Z axis home, emergency stop, and limit switches, as well as a few additional outputs and it exposes the enable functionality of the stepper motor drivers, allowing you to disable all stepper drivers if needed.  I'm planning on using Mach3 for the initial prototypes and then moving to a microcontroller based G-Code interpreter (possibly based on GRBL) once development is further along.

Other than the main PC breakout board, I've also designed boards for mechanical end stops (seen above) and a stepper signal splitter board (seen below) that will allow two stepper drivers to be controlled by the same signals, allowing for some interesting mechanical drive options.

While designing these boards, I tried to keep them single sided if possible, keep the required part counts low, and use big parts where applicable to make them easy to construct.  The idea is to make them easy to "bootstrap" via traditional DIY PCB etching methods and easy to mill once I've got a machine up and running.


Why I <3 OpenSCAD

Friday, March 25th, 2011

So my CNC design is coming along nicely now, and I'm really liking developing it in OpenSCAD.  I'm trying to organize everything well to make the design easy to modify and come up with a good work flow for going from designing individual components, to fitting them together into assemblies, to actually generating the toolpaths to cut out the parts on a CNC router.

One of the cool things you can do if you build full assemblies from your individual parts in OpenSCAD (or any CAD program, really) is do a quick first pass of your design and make sure everything fits together nicely.  Here's an example issue I caught when looking at my X-axis assembly:

One of the pipes that span the X-axis frame intersects the spans of the gantry.  To fix this I can open the include file for the X-axis and change a single line that defines how wide the  spans are or the  spacing of the guide rods, recompile, and end up with this:

Problem fixed!  If I extend this approach and make an assembly for each full functional unit, each axis, each tool head, etc., I can throw them all together and see how my whole final machine will look and identify problems with the design before I start cutting parts.  Moreover, others can also easily see how the hole thing fits together, make changes, and check their mods easily as well.  That's the plan at least.


Progress Update – 3/8/11

Tuesday, March 8th, 2011

I haven't been posting any projects, but I've definitely been working on stuff!   If you don't follow my Thingiverse posts, I've leaned a little about character modeling in Blender and made me a ceiling cat for the shop:

I also made some spools for jumper wire that fit in my trusty electronics tackle boxes:

I've also been working on a set of parts that'll attach to a standard Cupcake CNC to add fume hood functionality for a fellow Makerbot operator.  It's not done yet, but the parts I have done make it look like a little oven, which I think is pretty awesome:

I've also been working on the CNC router at CCCKC, which has had a few successful test cuts and should help me finish a few long-running projects I've had on the back burner.  Check out this CCCKC blog post for video and some more info.

Lastly, I've been working on my self replicating CNC project again.  I've decided to make this project even more ambitious and I've acquired most of the hardware that I think I'll need to finish it up, or at least get it off it's feet.  I'm also learning OpenSCAD and doing all my initial design and prototyping in OpenSCAD.  I'm going to try and use OpenSCAD to model all the milled components in 3D and then use OpenSCAD's 2D rendering capabilities to generate the DXF files that will eventually be used to generate tool paths to actually mill the parts.  I'm trying to make the design very parametric and well organized so it'll be easy for me to tweak and easy for others to modify use the parts they have on hand or make new  derivatives.  The CCCKCCNC being up should help prototyping as well.



Quick Projects – Building a CNC Mill Stand and Enclosure

Saturday, December 25th, 2010

Time for another quick project.  This time it's a cheap, simple CNC mini-mill enclosure using materials I had readily available, a re-purposed parts washer, and a combination of two of man's greatest inventions, duck tape and cardboard!  Well, not really cardboard, but corrugated plastic called coroplast only because cardboard isn't exactly waterproof.

To provide some background, I picked up a CNC converted X2 mini-mill from a local hobbyist a few weeks ago so I could try my hand at making some metal stuff.  It came with a DIY wood stand that was a little bigger than I would have liked, a slightly leaky PVC/wood/expanded foam flood system, and an open front that didn't stop little bits of metal from flying out and on to the floor.   I wanted to build a new stand and enclosure that I could use a flood system with and that was fully enclosed so I could use it inside without having to worry about clean up.

I found a build I really liked that I wanted to do here.  Basically, the idea is to set the mill in a cheap parts washer and create a cheap enclosure to set on top.   Just like the stock shelving project, I tried to make the most of a single sheet of material, so I tried to set a hard limit of using only one sheet of coroplast to complete this project.  Here's a list of all the stuff needed to make a full enclosure:

  • Harbor Freight 20-Gallon Parts Washer - Wait till it's on sale, I got mine for $70
  • 1 4'x8' sheet of 4mm coroplast in the color of your choice - I got mine at Lair Plastics in KC for about $10
  • 1 or 2 60yd rolls colored duck tape - I think you can get away with a single roll if you're careful, but I had to start another roll to finish out the project
  • 4'-5' of 1" wide 1/8" steel bar - this will be used to support the enclosure
  • 6 small magnets - To fix the steel bar to the parts washer
  • 28"x32" sheet of 0.118 acrylic - I got this for free from someone, I assume it's a standard size at some hardware stores
  • 1 drawer handle to attach to the acrylic sheet

Build the Stand

Start off by by assembling the parts washer and removing the parts you won't be using.  Be careful when removing the lid lift hardware, there's a spring in there that popped out when I was removing it that looked like it would hurt quite a bit if it hit you.  There's also a square hole in the side of the parts washer bin for the pump that comes with the stand.  You'll probably want to block that off with a few strips of duck tape, or maybe a big sheet magnet if you want something that will be easier to remove in the future.

Next you'll need to build something to set your mill on inside the wash tub.  What you set the mill on will probably depend on what you have on hand, but I used a 12"x24" sheet of 3/4" HDPE with eight 3/8" threaded rod stand offs that were coated with plasti-dip on one end so that they didn't scratch the bottom of the parts bin.  I left two of these threaded rod sections longer so I could mount additional hardware (cable management, flood nozzles, lights) inside the enclosure later.

Build the Enclosure

Next, you'll need to cut all the parts you'll need out of your coroplast sheet.  My sheet was not exactly 48 inches by 96 inches, so make sure you measure the size of your stock beforehand.

After you've cut all your pieces out, find some space to work and start seeming things up with your duck tape.  It's best to leave a little bit of a gap between pieces at this point because you'll want them to fold easily.  There's no set pattern here in terms of what get's seamed up first, just do what you think is logical.  If you mess up, in most cases you can just pull the tape off and start over.

Along the way you'll probably want to cover any exposed sections of the internal comb with tape to prevent debris and liquid from finding their way in there.

After the top, back, and sides are in place, take the 4 triangular pieces you cut out of the left and right flaps and tape them into the bottom corners.  I also took some of the scrap and added triangles to the front of the enclosure because the top was sagging and I ended up leaving them in place.  Install the front and back flaps first and attach them about 2" from the bottom of the enclosure.  After the front and back flaps are in place, install the left and right ones.  Here's a picture of the left flap just before installation:

After the flaps are in place, you'll want to route your cabling.  I did this by cutting a flap in the back of the enclosure.  I cut only half way through the top of the flap (which is much easier to do "against the grain" of the coroplast) and folded it inward.

Lastly, take your acrylic sheet and tape it in place along the top.  Remember to tape up both sides.

Bringing it all Together

One last minute addition to construction was adding some metal rails attached to the stand with magnets to support the whole enclosure when it was completed.  The corners on the bottom of the enclosure rest on these rails and support the entire enclosure.  Ideally, these rails would be 28" wide but I only had a 48" strip of steel to work with, so both of mine are 24".  I taped three 1/2" rare earth magnets to each, approximately 6" apart.

After the  rails are in place, simply fold all the flaps on the enclosure up and slide it over the top of your mill that's already in place inside the parts washer basin.   Fold down the front and back flaps then the side flaps and shift the enclosure into place.  Here's a shot of the inside of my enclosure once it was in place with the flaps down:

And here's a picture of the entire enclosure and stand when finished:

Construction Tips

Tack sections that you're taping together with a small square of tape to make things go more smoothly.

Internal seems can be tricky, so you may want to do them in two or more strips.

When sizing up the flaps, I tacked them in with 3 squares of tape and tried them out.  You may want to do this in your setup to make sure everything's looking good before taping everything down.

Final Thoughts

Overall I think this enclosure will work well for the time being, and it's not bad for under $100 total to construct.  I think the Z and X axes may end up bumping the enclosure, but only toward their extremes.  One thing I did notice about the white coroplast is that the oil I use to keep the machine lubricated seems to permanently discolor it.  Not a huge deal really.  It'll probably be a bit before I get around to getting the flood system up and running, and I'll probably make some modifications to the setup when I get to that, but I'm anxious to see how well everything works when I'm splashing cutting fluid around inside.


CNC Project Update – Stepper Motors, Controllers, and Miscellaneous Electronic Bits Acquired

Sunday, December 27th, 2009

Progress on my CNC router platform has been progressing slowly but I've hit a few milestones.  I got 4 RepRap 2nd generation motor controllers assembled and tested and have acquired 4 new NEMA23 steppers and one used high torque Xylotex NEMA23 from  the local swap meet to use in the prototype.  I got the X axis up and running and was quite pleased with the torque even the smaller steppers put out.  I also picked up some nice 4-pin sockets, terminal strips, and limit switches for the prototype build as well as a few other electronic goodies at the SSARC Hamfest about 2 months back.

As far as design goes, I've decided against the 1" square tubing and skate bearings design pictured above.  It's just too bulky for anything other than the X axis so I'm going to switch over the the more traditional precision ground shafts and bearings for linear guides on all axes at this point.  Other than being bulky, I like the design and will probably try to utilize it at some point in the future.  I've already acquired some shafts and bearings for testing this new setup but have yet to cut new bearing brackets to install on the boot-strap platform.   The overall design is on its second revision on paper with details for the X and Y axes specified and sketched up.  I'm looking at alternative linear motion setups that I could possibly fit within the specified budget so it may undergo another revision before I start cutting parts for the boot-strapped version.

This project will likely progress slowly for a bit longer as I seem to have outgrown my current work area.   I'm hoping to be able to move to a more suitable location in a few months time and set up a proper workshop, or at least that's the plan.