Dremel Flex-Shaft Mount for Zen Toolworks 7x7 Mill

I wanted to try out AutoDesk 123D for designing parts to be 3D printed on the RepRap, so I designed a holder for a Dremel Flex-Shaft so I can mount it on my Zen Toolsworks 7x7 Mill.

Drawing the model in 123D was fast and easy. I'm looking forward to using it for other things. I constructed this by starting a sketch in the XY plane and drawing the long rectangle, the two concentric circles for the holder part, two three-point arcs for the fillets (it may be able to do that automatically, I didn't experiment with that), and a couple of rectangles for the tabs. The sketch lets you multi-select the areas defined by the lines, so you can then extrude just the parts of the sketch you want. For the horizontal holes I started sketches on the faces where the holes needed to be (just a circle), then push/pulled it through the solid. Very simple construction process, and it maintains all the sketches and push/pull operations in the Browser, so you can easily go back and change them later.

I drew all the holes to the exact size. I know that the RepRap typically makes the holes a little small, but I wasn't sure if it would be better to draw them a little bigger or drill them out.

Once I had the model done I saved it as a .stl file and got it going on the printer. This is about as easy as it could be. The printer has home switches on all the axes, so it's just a matter of opening the file and clicking 'print'. It takes it a minute or two to warm up, then it's off and printing.

It took about 15 minutes to get both parts printed. They came out pretty good. The horizontal mount holes are only 5mm from the edge, and I noticed that the layers were a little wobbly on that narrow part, but nothing serious. I think in the future I should probably try to provide more material around horizontal holes like that.

I ran a drill bit through all the holes to bring them to the target size. It seems to make them about 0.5mm too small. That works out pretty well because the drilled surface is more precise and smooth anyway. Since the back of the part that mounts to the tool plate on the mill is a bit wavy I decided I'd face it on the mill to make it flat and square with the bottom of the part( which is glass-smooth from the bed of the printer).

Milling the plastic part works pretty well, but you have to be careful to not go too deep. Because the interior of the part is an open network (I'm using 30% fill) you can't cut away very much wall and retain the strength of the part. Also, where the filaments stick to each other isn't nearly as strong as the  plastic itself, so if you try to cut nearly through a layer it'll tend to peel off in strings. It's probably best to plan to cut not more than halfway through the filament depth, or possibly to impregnate the part with epoxy (or maybe wax) before milling. I ran the parts on the big mill with a fly-cutter, and other than tearing up a few filaments, the milled face came out great.

Mounting the part on the mill was fast and easy, all the holes were exactly where they were supposed to be, and it was all square and flat. It bolted right up and is good to go.

Fortunately, my Flex-Shaft is the old-style with a simple 12mm tube, so no funky ergonomic shapes to deal with.

I think next I'll make an adapter plate system with some magnets in it so I can quickly swap out simple tools, like a pen holder, magnetic field sensor, touch probe, etc.

iPod Macro Photos

I ordered a couple of small lenses from Surplus Shed (#L4471) to try out as macro lenses for the iPod Touch. They arrived today, so I tried taking a couple of test pictures with them taped to the front of the iPod. I was a little disappointed, as I was hoping to get tighter close-up with it. So, naturally, I stacked the two of them together to try it that way. This is the result.

These are images of the pixels on my monitor (~92 px/in ) taken with the iPod and my DiMage Z2 in SuperMacro mode. The image resolution ends up being very similar (in this test each screen pixel ends up being about 12 pixels across), but the Z2 does a better job overall, with better color and, of course, more pixels overall. The iPod does pretty good though, certainly acceptable for quick shots of stuff. I'd like to try another lens with a different focal length (these are 51mm) to see if I can get up closer.

Here I got a picture of a US penny. The Z2 will take better macro pictures than this, but I didn't put any effort into setting up, I just snapped a handheld auto-focus picture with ambient light. But I did the same thing with the iPod, so it's a reasonably fair comparison of taking a photo under these conditions.

Web-attached pan tilt camera

With some help from Brandon and Ben I got the mechanics for the pan tilt camera rig going. The servos attach to an Arduino which is connected to a computer running a Windows web service that provides access to the camera.

I had an issue with the movement speed initially, and had to update the Arduino code with some position speed ramping. That went well and it is moving more smoothly. It flops around a bit, but I think that is mostly the slop in the mechanism.

The web service supports tagging of positions so that interesting views can be labeled. Once labeled a single button press takes the camera back to the associated position.

I will post some video of it in action soon.

Mail Rings

I'm working on a 4 in 1 mail wristband as a gift, and I thought it would be interesting to try welding and brazing some rings. This is the result, prior to an acid bath and more polishing. Unfortunately I ran out of oxygen before I could get very far with the brazing, and I didn't manage to close a ring with the brazing.

I deliberately picked some 'worst case' rings, which had wide gaps. These were fairly easy to close, and I think that well-formed rings would come out very nice.

I wouldn't want to do more than a few hundred like this, but I think smaller pieces shouldn't be too bad.

Tippy forge

Here are a couple of videos of the tippy forge I've been working on for the Omaha maker Group. At this point it just needs the frame to hold it and a handle to make it easy to tip. There is a little leakage from the input that we need to get sealed up, but it works quite well so far.

Motor demonstration rig

One of the interesting projects from the Omaha Maker Group meeting on Jan 10. Ben put together this little motor demonstration rig with a couple of magnets, a 3D printed frame, and the armature from a commercial motor. Here he is just holding a couple of wires against the commutator as brushes. It's interesting to see the effect of adjusting the brush positions relative to the magnets.

Arduino Fio and other bits

Received an Arduino Fio and some other bits in the mail today. I was planning to use this for the Omaha Maker Group Makery Monitor Micro (OMGMMM), but I did not pay close enough attention when ordering and pdid not notice that it doesn't support the USB serial. I didn't have the budget for the XBees for it, but I guess I will have to do that sooner rather than later, as the web page and web services for it are getting close to beeing deployable. It even supports driving servos via the web service.