Asinine “Cordless Broom” restored

2016-10-12-23-49-53bA few years ago I got this ridiculous thing from a thrift store: the Black and Decker “Cordless Broom” (differentiated from regular brooms, which I guess somehow have cords???).

It’s basically a really weak leaf blower, but it looks like a giant bazooka, and it was $5 at the time.

versapakIt runs on obsolete “VersaPak” batteries, which were part of a proprietary tool battery system from at least 10 or 15 years ago. I had an old electric screwdriver that ran on one of these around then. Each battery was a 3.6V NiCd pack, and this unit uses two of them at once to run at 7.2V.

I wanted to revive it, but I wasn’t going to be hunting down decade-old batteries on ebay to do so. I decided to use 18650 rechargable Li-ion cells (the same kind used in laptop batteries) because they’re 3.7V each (close to the original’s 3.6V) and I had a bunch lying around.

I popped the housing apart, drilled a hole in the side, and added a 2.1×5.5mm panel-mount female DC barrel jack that hooks to where the VersaPaks would connect in. Now I could power it from my bench power supply to verify it worked, and it did.

My first attempt at a battery solution was a single pair of 18650 cells in a cheap ebay case. This worked, except the wires that came pre-soldered to the battery case were a very small gauge, and I actually felt these wires heating up when I used it. This was no good – I was a bunch of my power to wire resistance! Also, the thing ran the pair of 18650s down pretty quick.

I don’t have any pictures of any of that because I did that part a long time ago, then lost interest. Recently, I felt like doing a little project, and the thing was sitting here, so I finally finished it.

2016-10-12-23-49-21bI got two new two-cell battery cases, and snipped their tiny pre-soldered wires. I soldered on good 22 AWG wires direct to the outputs, and hot-glued the wires for mechanical strength. I ran both sets of battery pack wires to a single male DC barrel plug, so as to run two pairs in parallel (2S2P in battery-people speak). I screwed the two cases to the housing (there’s plenty of room to screw into where the VersaPaks used to plug in) and plugged it in, and presto. No more warm wires and much better battery life.

I like this thing because it can quickly blow sawdust and stuff in the shop without sending screws and heavier stuff flying around. Also, Reginald is terrified of it.

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MPCNC: Portable and Wifi-enabled

2016-07-30 20.28.30bI’ve come to realize that I can’t run the MPCNC in my office — it just kicks out too much dust. I could add a vacuum, but I bet there’d still be a bunch kicked off. Therefore, I’ve modified the machine to be portable and wifi-enabled, so I can take it to the shop out back.

To do this, I’ve done three main things:

  1. Attached a Raspberry Pi running OctoPrint, with configuration made so I can upload gcode via a Windows share (samba).
  2. Added handles to either side, and eyelets with rope for a shoulder sling, allowing it to be tipped over, collapsed, and carried out by myself.
  3. Protected the electronics with a removable cover made of hardboard.

Details after the break if you’re interested.

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MPCNC: Lumber ID

If you’re like me, you live in constant fear of criminals breaking into your backyard shed and stealing your valuble scrap pieces of 2×4. Well, worry no longer:

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Now you can protect your lumber scraps by engraving your name in giant letters across every individual piece, thanks to the MPCNC.

MPCNC: new pen holder and trochoidal milling

2016-07-16 13.17.14bI improved the Z coupling, made a much better pen holder, and discovered trochoidal milling, which, in addition to making actual milling easier, draws cool pictures if used with a pen.

The pen holder was actually somewhat complex. The pen I wanted to use was a Bic 4-color, and its barrel has a very slight taper to it, so I had to model it fairly precisely and it took two prints to get the dimensions right. Now that it’s done, though, I can get really nice, repeatable drawings. I’m thinking of developing an algorithm to convert images into combinations of the pen’s four colors and emit gcode to approximate color printing. It will be ugly due to color theory (there’s a reason printers use cyan/magenta/yellow/black), but it might look neat.

Video/pic:

db-tor

MPCNC: it drew this

The MPCNC with my rudimentary pen holder was able to draw this. I need to add some kind of spring downforce on the pen to deal with small differences in depth (which is why the lower left is faded). That should also help with pen accuracy, because on the high parts it’s grinding the pen too hard against the page and its getting stuck. I  also need to turn up my overlap to get it to solid fill better.

draw1

MPCNC: A relay-switched outlet box

On Thingiverse I’ve posted a model and schematic for a relay-switched outlet box. This will let you switch an outlet on/off with an Arduino pin. That’s nothing new, but it’s a box that puts all the components together in a neat and safe package.

The model holds a U.S. power outlet, IEC C14 power inlet (for use with common PC power cables), a cheap arduino-compatible 5V relay module, and a small Dupont connector for the control relay module’s inputs. The wiring diagram below shows how to make one outlet switched with the other being always on.

The intent of this model is provide a switched outlet for my Mostly Printed CNC machine (MPCNC). It’s designed to be narrow so it could mount on the side of the machine to (a) provide always-on power to the power supply and (b) provide switched power to the AC spindle motor. That said, this model is a general-purpose switched outlet, so you could use it for any automation of AC power you need.

See photographs below for assembly directions. Notes:

  • The faceplate is a standard one cut down to fit the width of the box; you could modify something like this if you had to print one.
  • Relay modules tend to vary in size — move the screw posts in the model if needed.
  • The relay control wire is just three double-female dupont jumper wires taped together and hot glued in place.

WARNING: This switches high voltage! If you are unsure how it works or how to build it, consult someone with electrical experience before proceeding! This isn’t hard to build, but it can kill you if you touch the guts when it’s live, and it can start a fire if wired wrong or with insufficient gauge wire (18AWG to probably not die, 14AWG to meet code).

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MPCNC: Custom mods and part of a dickbutt

I’ve posted two custom parts for the MPCNC: a wire harness and a customizable end-stop holder.

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This test model works as well in 2D as it does in 3D!

I tried a test run of the Optimal Fabrication Test Model (it’s dickbutt…we talked about this).

Results were…mixed. It started out strong by making key outline portions, so I left the room. I came back when I heard the spindle inexplicably struggling from downstairs. I come back to find the spindle has sunk all the way into the foam, and the nut that mounts the endmill to the tool has itself ground a sizable trench through the foam. Bits of foam are everywhere.

It turns out two separate failures happened. First, the Z coupler came loose…that’s my fault, as the plans called for nylon locknuts, but I couldn’t find any locally, so I used plain hex nuts, so the screws tightening it vibrated loose. Locknuts: ordered.

Second, there was a flaky connection on the X-axis, which is why it’s a vertical trench instead of a vaguely dickbutt-shaped trench. Apparently the wire I used doesn’t like to crimp well in Dupont connectors, so I crunched them all harder and added a bit of solder to be sure.

I 3D printed a pen holder to attach to the tool, so I can do ink-based tests while I work out the kinks. I did a dickbutt print on the same crappy foam, offsetting it a bit upward. The result is surprisingly good, given that the foam is nowhere near level, and I used the same program that assumes a 1/8″ endmill. Look at the solid ink on those eyes…nice!

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