Wednesday, October 6, 2010

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 ;)

Saturday, October 2, 2010

DIY Millennium Falcon

Carys was turning six at the beginning of October and had recently become StarWars obsessed (we let them watch the original 3 movies a few weeks back and they loved them).  Lin and I like to add a few home made presents to the mix on the kids birthdays; So, we decided to make a few StarWars themed things for Carys' birthday.

Lin started out making a set of StarWars figures using wooden craft pegs (more about that on her post here).  We were going to make a Millenium Falcon using a couple of plastic frisbies, but then thought it'd be nicer to create something a bit larger and more durable so that they could use it with the figures for some make-believe fun.

It took us a little while to decide on the components to use.  We found this weird wooden board at the local thrift/charity store.  I think it's used for carving meat and the grooves capture the juices (there's even a "patent applied for" stamp on the back).  I forgot to get a picture of it in its original state; the picture below shows it after a little bit of modification.  It was originally symmetrical - I rounded off one of the handles/ears and cut a groove in the other in preparation for adding the front prongs.

Here's a quick overview of the components:

There's the weird carving board, a plastic lid (another lucky thrift store find as it fits perfectly in the groove of the carving board), some PVC pipe (2" diameter) and a 90 degree elbow joint (both from Home Depot).  There's a dollar tree airfreshener case (the white tear drop thing by the black pipe) and some wood.  There are some other bits and bobs that aren't in this picture (I hadn't figured out what was going to be used at the time): a hinge for the cargo bay ramp, some more wood for the internal walls, screws, nuts/bolts, wood glue, some grey spray paint, a few plastic bottle caps, and the outside case of a CD spindle.

From the 'ingredients' picture you can see that I cut and sanded the carving board first and then made the front 'prongs'.  For the prongs, I looked at a few online plans and scaled the dimensions to fit the cutting board.  I used a scroll saw to cut out the shapes and then screwed and glued them onto the main board.

While the glue was drying I made the internal structure.  It's made from the outside of a CD spindle and some wooden boards (2" hobby board from Home Depot).  I cut the CD spindle to fit the height of the lid and then measured out the boards to fit up to the edge of the curve.  That was a bit of a mistake as the lid didn't fit with the boards that long and I ended up having to sand the ends down a bit.

I thought it'd be fun to have internal doors but didn't think the spindle would survive with large chunks cut out of them, so I just put some painters tape where I wanted the doors and then painted it all leaving some see-through areas after the tape is removed.

I gave the lid it's first coat of paint, bolted on a few bottle caps and wood disks to mimic some of the structures seen on the original, and then gave it all another coat.  The lid needs to be cut in a couple of places to make room for the cockpit attachment/corridor and for the cargo bay ramp.

I used a miter saw to cut one end off the PVC elbow (so that the cockpit would face forward) and to cut an angle into the corridor (makes it easy to screw the pipe into the base). My first attempt failed as the corridor was too short, but I had plenty of pipe left over for another go.  Everything was given a coat of paint.

I cut the airfreshened body down to a size that would fit snugly over the pipe and then used hot glue to attach it.  I like the fact that the cover comes on and off so we can put pilots in there.

 Here's the final set-up (with cargo bay ramp attached with a hinge):
Lin made some ace characters for Carys' birthday and the two presents go really well together.  I love the fact that Darth Vader's helmet comes off to show his pale splotchy face :)

And, just to finish off, a gratuitous set of action shots:

Thursday, August 26, 2010

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, 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!

Saturday, July 31, 2010

Rescuing a CedarWorks Swing Set

We had the good fortune recently of being offered an old play-structure by a lovely couple who'd recently bought a house with it in the garden, but their kid was too old for it. They'd tried to give it away a few times over the last year or so, but no one who came to look at it had any clue how to take it apart - I'm beginning to suspect that they were just sensible and realised how much work would be involved in deconstructing and reconstructing it all ;)

It was completely worth the effort though. These CedarWorks play-structures are fantastic (seriously, check out that link, it's like swing set porn) and there's no way our kids would ever have had anything like this under other circumstances. We managed to salvage the whole thing for about the cost of the metal steering wheel it came with (~$160).

I took a look and thought, yeah, that'll come apart easy and should squeeze in our back-yard. So the missus and I went down one Sunday with a big U-Haul truck (one of these) and spent about 4 1/2 hours taking it apart with the help of the original owners (and Jessen and Lani who were looking after the filthwizards). We'd actually been down the day before to show the kids and to get started (we spent about 1 1/2 hours there that day). These things are definitely built to stay up!

Most of it was pretty straightforward to deconstruct, it's mostly held together by long bolts and hex-screws. The hardest part was removing all the dowel rods... These were all kept in place with nails driven through the main posts... this turned out to be the biggest pita time-sink of the day. I ended up clearing some of the wood around each of the nail heads by hammering a 7mm socket around the top of them and then using a claw hammer to pull the nail out. We left parts of the structure intact (the smaller tower, the monkey bars and 3 rows of the larger tower). Phew! That was quite hard in the midday sunshine... and guess who forgot his hat! Doh!

We did joke a couple of times that we may have landed ourselves some very elaborate firewood.

Here it is, taken apart and stored down the side of our house waiting for some attention (both of us quietly hoping not of the bonfire variety):

Whilst taking it apart we found that the lower 6 inches of the structure was rotten (including the A-frame support beams/crossmembers) so we'd have to come up with a plan for fixing it up. A few of the dowels were rotten as well and one of them wouldn't come out, so we ended up sawing it in half in order to get the frame apart and out of the garden.

We decided to stain the wood to protect it from further water damage and to make it look a bit nicer. We picked up the stain from Home Depot (Red, Brown and a small pot of green for the horse swing) and set to work.

It took a couple of weeks of preparation (mainly painting and grabbing some supplies) and an entire weekend of painting, sawing, hammering, drilling, lifting, squeezing, sneezing, spluttering (I got a lot of sawdust up my nose and in my mouth) and standing on-top of things with my mate, Jessen, bashing away with a big rubber mallet to get it finished and in a good state to play on. I sawed off the lower 6" or so of the entire structure (16 vertical legs and 3 A-frame legs) and replaced the unsalvageable, A-frame crossmembers with some 8' 4"x4" from Home Depot.

It was going dark on Monday night by the time the kids got a chance to test it out - They were very excited and I had to fend them off for a little while whilst finishing up the A-frames. You would have thought the sight of me running back and forth with a big drill in the twilight would have been intimidating enough... apparently not.

Well, it's still not quite finished. The platforms that go inside the main structure still need sanding and painting, but we can do those piecemeal. Hopefully this means I've got some time to get back to building that CNC machine!

It feels like we're pretty good at not necessarily biting off more than we can chew, but rather biting off enough to give us very sore jaws... It really felt worthwhile when Ffion came running over and hugged my leg, saying "you're the best dad ever!" and Carys shouts out (from the apex of a high swing) "This is AWESOME!". Yeah fine... they have me wrapped around their little fingers...

Wednesday, June 23, 2010

CNC Machine Build - Part I

I've started a 'little' project that promises to take up most of my free time (what little there seems to be of it at the moment) - I've decided to build a CNC machine.

To be honest, I've had gadget lust for a CNC machine for some time now... all the talk on the blogs about Cupcakes and Makerbots and RepRaps got me looking into CNC machines some time ago. I could never bring myself to spend the money on one though since they're a little pricey. The cheapest options that looked any good were the Zen Toolworks machines, which came with stepper motors but no power supply, controller boards or router/spindle. The cheapest of these can be got from Amazon for under 350 dollars. Still, it only works on a 7"x7"x2" area. The next machine up is around $600 and works on a larger area of 12"x12"x2". At this price I get a little scared and only being able to carve a foot is a little disapointing.

Anyway, I held off for ages but then came across these plans at which detailed the construction of a CNC machine that would cost a little bit more than the larger zen toolworks one (all inclusive), would use mostly materials from Lowes or Home Despot and also promised to be pretty easy to follow (a definite bonus for me, since I chose to do needlework and cookery rather than woodwork and metalwork when given the choice at age 13...). I've seen lots of online instructions for building various types of CNC machine (like this one, and this one, and this one... well, you get the idea), but they all left me a bit confused and unconfident about being able to build something worthwhile.

The promise of the solsylva plans were enough to make me order the 25"x25"x7" plans to see if they were idiot proof enough to give me the confidence to get started.

I received the plans a few weeks ago, read them over and then excitedly started to spend money on wood, bolts, washers, screws, pipes, all thread (threaded rod), forstner bits and skate bearings. So, yes, they appeared to be detailed and simple enough for me to follow from start to finish.

I like the fact that the solsylva plans allow for someone who doesn't have a truck. The wood measurements are for planks 8' and smaller, which fit fine in my little Nissan disappointment (with the back seats down). Recently I've been taking advantage of craigslist in order to pick up a few power tools on the cheap. I got hold of a drill-press ($50) and a miter saw ($60), which have been very useful so far. You'll laugh at me, but they were a bit intimidating to use at first - especially the miter saw. I kept having these images running through my mind of flying fingers and trips to the ER (in my defense, the miter saw is very loud). After a bit of practice I've become flamboyantly reckless much more confident. I'm definitely enjoying learning the new skills involved.

The pictures at the start of this post are the main base of the machine, put together over a few hours on the weekend. In the picture below I've added the X-rails and X-stepper motor support (this was done on the following weekend).

So far, it seems that things are going well. I'll keep you posted.

Wednesday, June 16, 2010

Upcycling: wine rack to doll bed

We found this little wine rack in the local thrift store (savers). Lin thought it'd be cool to turn it into a bed for the kids baby dolls. We bought an American Girl doll crib ages ago at a garage sale that was made of plastic and it inevitably fell to pieces... So the idea of the girls playing with a more sturdy one that I'd made was appealing, especially since they had a lot of make believe fun with the old one.

The idea was very simple: Take the rack apart, stick it back together again with some wood-glue for added strength, cut out a base, screw this on and then paint.

I was going to make a crib by adding doweling bars between the cross beams, but the way the rack was put together made this a bit too fiddly so I decided to just replace the bottom beams and make a baby bed instead.

I sanded the pieces to get rid of some of the murky dirt. Then I painted on some wood-glue to the ends of the beams, reattached them and left it all to dry overnight (with a toolbox weighing it all down from above so that it'd set straight).

I used one of our "new" purchases (a very old scroll saw) to cut out a base. Very straightforward really, just measure the distances on the wine rack, mark those out on some wood and then cut.

Ooo look, a rectangular bit of wood ;)

I drilled out holes at the points where the new base board met the cross beams and then fixed the base to the frame using some wood screws.

Then I let the kids paint on a layer of primer. I think they quite enjoyed it.

After the primer had dried I painted on a coat of gloss. Hopefully that'll keep it in good condition for a while.

I wasn't sure if the kids were taken with it or not until the next morning when a couple of their friends came over for a play date. "Dylan! Dylan! Come and see! I've got something AMAZING to show you!" cried Carys. To be honest I wasn't sure what she was going to show off, but was very touched to find out that it was the baby bed we'd made. Poor Dylan was a little bemused as to why she was so excited ;)