CNC rebuild and upgrades

I finally got round to taking the CNC machine out of it's box and rebuilding it (after 7 years of being in storage). This happened over the space of a year - mostly because I got caught up trying to decide how I wanted to control the machine this time round. Previously I used LinuxCNC on an old PC, but I'd left that PC in the US when we moved back to the UK in 2012. I wanted to use a laptop so I didn't have to have a PC in the garage. I decided to try out one of the UCCNC ethernet controllers - which meant sorting out a power supply and box for all the electronic components.

I was pleasantly surprised that the machine rebuild went fine - there's definitely some more fine tuning to be done, but overall it still works well and I didn't have to replace any of the major parts. I did end up replacing the router, mostly because I wanted everything to be native 240v - I didn't like the idea of running a router from a transformer for long jobs.

Here's some in-progress photos:

I did add a few upgrades/changes during the rebuild. Something that was missing from the original setup were limit switches.  I found the Xylotex limit switch suggestion on the Solsylva site (this has been down for years, but the content is available on web.archive.org here). I 3d printed the limit switch mounts (3 different designs).

All the limit switches are wired in series using speaker cable.

The z-axis limit trigger is just a bit of Lego glued onto the z-axis lead nut...

These work really well and it means that I can automatically (and consistently) home the machine. Importantly, it also means that I don't have to worry about causing damage if I accidentally try to move outside of the machine limits (which I definitely did a few times when using it in the US).

I had to use a different mounting method for the Makita router. I found a few mounts on thingiverse that looked like they would 'almost' work - I ended up adapting this one for my setup (I extended and flattened the mounting point so I could attach it directly to the wood). This took a few iterations before it worked well - the detachable dust shoe (from the original designer) is a nice touch!

Now for some random makey makey pics.

First attempt at dust extraction - not ultimately useful, but the cut of the piece is quite pleasing.

Soundwave design for my eldest daughter (her favourite transformer).

Halftone map of the world for my mum's birthday. I used Jason Dorie's Halftoner program to create this (and the above soundwave image).

Finally, some dice boxes I'm still slowly working on.

CNC update

I just realised that I haven't posted about the CNC machine for over a year! Judging by the blog, it looks like I failed and let it die a quiet death... but in reality it's been pretty great; it is up and running and working better than I had originally hoped.

Admittedly, it took longer to get into a decent state than I had planned for, but then I never had a lot of time to dedicate to it and I am not "skilled in the art" (oh no, not by a long shot!). One of the main reasons for embarking on the CNC build was to push myself into learning a lot of new skills; with that in mind it's been a huge success :) I picked up more woodworking skills, some metal working skills, knowledge of CAD, CAM, gcode and learned a ton of other random facts and figures along the way. But, best of all, I have this amazing contraption in my garage that can craft things out of wood, plastic, foam and aluminum with speed and precision that I couldn't possibly hope to achieve by hand.

So, what have I done with it so far?  Well, a lot of the things I've made so far have been improvements and additions for the machine itself.  First off, I made some hold downs (thingyverse thing:776) and some knobs to go with them (gcode provided free by solsylva.com, which is where I bought the CNC plans from in the first place).

You can see the new knobs and a couple of the hold downs in use here, holding down some 1/2" MDF with some more hold downs being cut out.

At the start of the year I upgraded the leadscrews from all-thread to ACME rod (the cheap stuff from Enco) which meant that I needed new leadnuts (also from Enco) and leadnut holders - I designed these in CamBam and cut them out on the machine (after a few false starts mostly to do with my understanding of g-code).  I guess I should upload those designs to thingyverse really; though I'm not sure how useful they are to others.

The leadscrew upgrade removed a lot of backlash and resulted in faster and smoother performance.

I noticed that the cutting surface wasn't level so next up was to add some MDF planks and level them using the machine to mill the entire surface flat.  After spending a couple of hours following the router bit with a vacuum hose and still getting myself and everything in the garage covered in a fine layer of MDF dust (not nice) I decided the next upgrade should be a vacuum system - I went with the one described on the Solsylva site with one minor modification.  I had a lot of trouble getting the ring cut from a 2 liter plastic bottle to fit around the vacuum attachment, so I cut it open and attached it with duct tape...  frustrated, moi?  That was a bit unstable (and ugly) and I ended up replacing the tape with a #56 band clamp, which has been working fine so far.  I intend on cutting out a few more in order to have quick change vacuum feet with different length bristles on each of them.

It's not all been machine related production though.  Some of the first things I made were random carvings for the kids.  I carved their names into blocks of wood; made spirals, hearts and shapes for them to colour-in and mess around with; I made a few door signs for bathrooms; name plates for kids friends bedrooms; and a few other random objects.

I've also mocked up a small version of Carys' birthday present and cut it out on the machine.  I can't wait to be able to post about the completed full sized birthday project, but that's going to have to wait until it's finished. I love the fact that the kids birthday presents are always collaborative efforts with my lovely missus - all the projects are so much better when she's involved. Remember the colour conundrum?  That would just have been an ugly cardboard box with wires sticking out if it weren't for her creative talents and influence!

The current crop of unphotographed and unfinished projects include "kids name marble mazes" and rubber band guns.  I've been wondering how hard it would be to make simple versions of star wars ships like the millenium falcon and mill them out.  I guess I wouldn't be able to share the files though (or I'd risk getting sued).  The one thing I haven't really thought about is actually one of the reasons I thought the CNC machine would be ace - PCB milling.  It turns out that getting boards through DorkbotPDX is much simpler than milling your own (unless you're in a rush) and the results are fantastic - you can see a few of my completed boards here.

CNC Machine Build - Part III "It's Alive!"

Finally... after a lot of work and learning, the CNC machine is up and running.

I got the main machine finished and connected to a computer about a month ago, but I've been having trouble getting the z-axes working properly.  I tried tuning/adjusting it as described in the plans and I even remade the leadnut bracket, replaced the leadnut (twice), replaced the leadscrew (twice) and went through 3 couplers (these are only made out of cheap hose so that was no biggie). But, each time I put it back together, the axes would stall part way through a job (ruining the workpiece and usually destroying the coupler).  Eventually, I had to walk away for a week to cool down - at least that gave me time to make the Millennium Falcon dolls house for Carys' birthday.

Last weekend I went back to it.  I replaced the lead-nut and lead-screw assembly (again), this time making sure to buy some new threaded rod that was straight. It turns out that the previous ones were slightly warped and this was causing most of the drag. I guess that's the problem with building a CNC machine with bog standard threaded rod as a lead-screw, they're not meant to be used in applications where the rod has to be straight... I also updated the coupler tubing - I'd been using clear vinyl tube from Lowe's (the kind used for irrigation) which is weak and slippery. I bought some fuel pipe from Kragen and this works a lot better.

I did a couple of test runs on some kitchen cutting board and quickly realized that I'd have to work out how to hold/clamp things down whilst cutting.  I have a few clamps, but none of them fitted well between the slats so I made up a few hold downs using some left over wood and some bolts (you can see them in the picture below).

If I were to start this again, I think I'd opt for the more expensive ACME lead-screws/nuts and associated couplers. I spent a lot of time over the last few weeks tuning the axes and I think a lot of this would have been avoided if I'd gone with the better rods and lead-nuts.  All in all though, I'm very chuffed that this is actually working!  Last year Lin did a detailed pumpkin carving of our CSO, this lead to some geeky conversations at work about how you could automate the process but we ended up deciding that it was too complicated (mainly due to the issues of mapping an image onto the surface of a pumpkin in order to carve it).  I'm wondering if I can actually achieve that this year using the CNC machine - just like this guy did.  I bet all the CNC carving time gets eaten up with hearts and unicorns though... you know how it is ;)

CNC Machine Build - Part II

I bet you'd all thought I'd given up on this! Well, I just got a little sidetracked with a few other projects - the main one being the play-structure restoration and a load of garden "improvements" (I hope the landlord agrees!).

Well, I was wondering if I could finish it before posting again, but I got impatient. Most of the hardware is done, but there's still some fine tuning to do on the axes and I still have all the electronics to sort out.

I've been really happy with the plans I bought from solsylva.com, they are detailed and straightforward to follow. Most of this has been new to me, so I've taken my time (not that I had much choice) and it's been working out ok. It must have been comedic seeing my sleep deprived carcass hanging around the wood or screws/bolts at Home Depot around midnight on Saturdays, looking confused and eyeing everything up suspiciously. I had no idea what all the numbers and specifications meant on the parts when I was first buying them... trying to match up what was in the plans with what was on the shelves took a lot longer than I'm willing to admit.

There were a few choices to make when building the machine:

1. What wood to use.
2. What leadscrews/leadnuts to use (ACME rod or hardware store threaded rod).
3. What bearings to use.
4. What stepper motors, power supply and controller board to use (main choices seemed to be hobbycnc and xylotex.

Since cost is definitely an issue for me, I mostly went with the cheapest options. So, whatever wood was available at Lowe's/HD (pine and Douglas-Fir); threaded rod leadscrews (I can always upgrade to ACME later); hardware store tee-nuts as the leadnuts; skateboard bearings from Slam N City's ebay store; and I ended up choosing the xylotex 3 axis system kit for the electronics/steppers. I went with Xylotex over HobbyCNC mainly because the HobbyCNC kit appeared to require more work to get it up and running (like buying a separate transformer and fitting it in with the rest of the kit).

Here's a few in-progress shots:

This is after installing the y-gantry on the x-rails.

These are the bearing flanges cut out of kitchen cutting board. I bought some Forstner bits from ebay in order to cut the recesses. There are a few holes in the wood that require either spade or forstner bits as well -> the bits have been handy on other projects like drilling recesses for the bolts on the play-structure and making holes in our upside-down tomato plant buckets (you can see them somewhere in the middle of one of Lin's more epic posts).

This image shows the machine after the x-axes leadscrews and nuts have been added - there's one on each side of the machine. The x-axes stepper motor is connected to the two leadscrews by a belt and pulley system (suppliers and part numbers were given in the plans for these, so there was no confusion).

This is the cage that moves along the y-gantry rails and houses the z-axes spindle plate.

This shows the cage in position with the z-axes leadscrew assembly and stepper motor. The rods in the right hand picture are tension rods to press the bearings into the rails and allow the cage to run smoothly along the y-gantry black piping.

and here's the z-axes complete with spindle plate. The metal band at the front is used to clamp the router onto the spindle plate (as you can see in the picture below).

So, I think all I have left to do is to wire up the steppers, controller board and power supply; connect these to a computer (I'm planning to use linuxcnc on an old disused laptop - so old it has a parallel port!) and then work out how to use the software. Can't wait to carve out my first test pattern!