Pulling apart and old microwave recently, I pulled out the plate turner motor thingimibob and noticed that it rotated at around 6rpm. I've found this speed fine for turning rods, and I have also thought would be a good speed for a spit.........decisions decisions! Then our home microwave threw in the towel, and the easiest way to dispose of it was to pull it apart and throw it out in pieces. Another turner motor and problem solved.
This one ran on 21v AC, and I happened to have a few 12v AC transformers laying around. Seemed to turn it alright (I understand these motors get their speed from the frequency of the AC). The newer one I pulled out ran on 240v AC, even easier I thought, but I can't find a suitable box right now and I'm pretty cautious around mains power, so I'll stick with the low voltage one and use the other one for spit later on when I find a good box.
The actual building of this is pretty straightforward, but I'll run through how I went about it.
Step 1: Motor Shaft Attachment
Pondered what to do for a while, then saw that I had some aluminium pipe that was close to the right diameter. I figured that a small screw would grab onto the flattened side of the motor shaft.
Drilled a hole and tapped it to a screw I had available. I love putting my new tap and die set to use, finally having one, but those who don't have one could just run a normal screw through to thread the alloy, then grind the point off so its flat and doesn't chew out the plastic shaft.
Actually putting the rod onto this we will work on later
Step 2: Mounting
I measured the height of the rollers that the other end of the rod will sit in, and made the centre height about the same. No point being purely exact, as the rod will sit higher if its larger diameter, the rod will bend along its length etc. In this case it was around 90mm.
Cut one of the sides off the mount, and then held the motor in the right spot with a clamp ready to centre punch and drill. I turned the motor around so that the mounting holes were closest to the metal just so I could get the holes right.
Was intending to drill and tap it, but I didn't have any screws the right length for it, so I just went ahead and grabbed whatever was in the box that screwed in alright. Its not a high stress tool, just has to hold a rod and turn it overnight, so these will be fine.
Step 3: Wiring
This shouldn't be real hard at all for anyone who has done any work with electrical stuff, but I'll run through it for anyone who needs help with soldering. If your already good at that then just skip this section. Doesn't matter what way around we wire it, we just want the motor to spin.
First thing about soldering is flux. I know the solder is normally flux core, but adding your own doesn't hurt at all, and makes things a lot easier. Best flux I've found is made from rosin block that I bought from Deal Extreme. I think it goes under the name of colophony something or other, hard to find on there. I just crush a bit up in a bag, and mix it with methylated spirits (not sure what you call that in US and other countries, but isopropyl alcohol works as well I've heard). I've used barely any in about 3 years of using this stuff, so a little goes a long way. I store it in a little screw top pill bottle, and have a brush on the side that is stored there with an elastic band. Just brush a little on the part that your soldering. Note, this rosin flux is only good for soldering irons, turns black and stuffs things up if your using an open flame like gas torch.
Now to the actual soldering. You don't want to melt the solder onto the wire or pins, but rather heat the item your soldering to and hold the solder to that until it melts. In practice you can do things a little differently, but that's what your trying to achieve. I struggled as a kid with soldering, and was only when I learned this that I could do proper solder joints. Nowadays I often have a blob of solder on the iron and hold that onto the wire to tin, but ensure that its held there until wire heats up enough that it wicks along. You can tell when this happens as it flows nicely. The extra flux that you added really helps here.
Best bet is to tin the wire and the connections your soldering to, then just solder them together by heating and holding together. The extra flux brushed on each part initially is usually enough for this as well. Add extra solder if needed, but usually not needed.
Step 4: Rod "chuck" and Final Touches
After soldering the wires on, I mounted the motor back on and found that the power supply fit nicely underneath, clipping into some lugs that were on the base. That worked well to stabilise the whole thing too so it won't need to be clamped down.
For attaching the actual rod, I would like a chuck of sorts so it fits a variety of rod sizes, but I'm in a bit of rush to get this done so I can repair a rod for a mate. I found some garden hose that fit fairly snug on the rod, but was loose on the pipe on the motor. cut some slits and clamped it on with a hose clamp and it's great. Its crappy, but does the job perfectly. One thing I like about the hose is that its slightly flexible, and the pipe sticking out of the motor shaft isn't exactly perfectly square, so the flex of the hose overcomes this a bit.
I've made chucks for these in the past with something like a film canister or similar and just putting 3 screw through to clamp the rod. I'll make something like this eventually, but too many jobs on the list right now, so the hose will have to suffice
While this isn't exactly the grandest of projects, I'm hoping its been of some use for those who need a rod turner, or inspiration for some other project that could use a slow turning motor.
Any questions or comments please write away. Keen to hear any thoughts you have