In this instructable i will show you how to turn a useless piece of junk, with rotten batteries into a handy tool.
If you happen to still own a "roto-matic" then this is made just for you
Ok what is a "roto-matic"?
a roto-matic is a piece of junk, plain and simple, beyond that its a dremel wanna be, that was sold on infomercials in the early 2000's
it touted special features like
--10,000 RPM !!!!
-- BATTERY OPERATED, NO CORDS TO TANGLE!!!!
-- 40 BITS INCLUDED
while visiting my aunt and uncle in Lake Mary, Florida, I took my niece to the mall (a few times), and they had an "AS SEEN ON TV" store. I ended up with a assortment of stuff, some awesome and some not so much, the roto-matic with its "featuers" and 40 bits for a sale price of 15 bucks seemed like a steal
And it was a steal! From my wallet!
A little back history
growing up i lived (basically) in a fully functional wood shop, dad had everything, including a old 1970's dremel and all the attachments, which he still owns today and is in perfect working order
and let me tell you, that is a man's tool, if you don't plug it into the vintage speed control (steel box with a knob) when you flip it on, it will jerk your wrist 25% clockwise!
steel meh! just like butta!
so when i moved away, i wanted a tool that i had become dependent on, and when i saw the roto-matic i jumped on it, got it home and tried to cut a rivet head off and learned my awful mistake
heres the crap factor of the roto-matic
10,000RPM, 0 Torque, i could equip this thing with a cutting disk and touch my finger on it and stop the motor
battery's, 3.6v, and after spending nearly 30 min i had barley made a dent in the rivet, and the battery's were dead, 1/16th of an inch in and i needed an 8 hour recharge
Bits, while most (like 3/5ths) were the same size of a dremel, the rest were not, which you were required to keep track of 5! collars, wanted to grind and buff? Well you had to remove the chuck screw, replace the collar, refit the chuck, fit the bit and go on. Im sorry, thats stupid
I think it lasted a week before i threw away all the non "standard" size bits and collars, it maybe lasted about 2 months before i just threw it in a box to forget, since at the time i only lived 10min away from my parents house, and access to real tools
fast forward 6-7 years, and i live across town, im married (which sometimes prevents me from just up and leaving the house) and i want a dremel darnit!
i looked at the 26$ battery operated one at walmart, with 0 bits, and remembering my dislike for a "dremel on a cell".
Also the "engraving" model which is 120v powered, down at Lowes, again with no bits, and the real dremels, which, honestly the 20$ model + bits is not really in my budget atm, let alone a 60-100$ kit.
Darn, all i want to do is cut, sand, and drill some pcb's or abs project enclosures ...
enter mom, who was cleaning out the garage and presented me with a box of "my crap", that i had forgotten i was storing there. Digging tru the box of crap, i found a hot knife (sweet) a glue gun (sweeeeet) and my roto-matic (ugh, well maybe not?)
Welcome to my instructable! (gah finally, you friggin windbag!!!)
Step 1: Basic Plan & Stuff Needed
Turn this useless dead hunk of junk into a usable tool by removing the dead / useless battery pack and hooking it up to a wall wart
Phillips head screwdriver with a narrow / small tip
Soldering iron, mines a 15/30 watt radio shack, and i have not used the 15 watt setting in the nearly 20 years I have owned it
Damp "yellow" sponge
Solder sucker or wick, i just use the red bulb from radio shack in this case
jewelers file, fine grit sandpaper, or any other similar abrasive to clean off the corrosion from the solder points
Solder, 60/40 rosen core in this case (ill switch to silver when this spool is used up)
Zip Lock style baggie (for the nasty battery to go in)
the wall wart i choose is a 5v switching model with a 2.5 amp load rating, ... why?
well theres no way this motor is speced for exactly 3.6v, thats what the old battery pack took to charge
The motor itself, probably can take 12 or more volts, but theres no markings on it, so i choose 5v @ 2.5 amps because its what i found in my "box of warts" with a similar voltage, and a nasty amp rating.
Which allows an increase in torque, and ensures me that if I really really push the tool I probably would burn out the motor well before even warming up the supply, remember were not trying to machine tool grade steel here, just cut, drill, and sand pcb's and project boxes
Switching, cause its what I happen to lay my hands on, and it has the bonus of being tiny, which is nice
after reading some other instructables, I thought I should test the load of this thing to ensure safe operation, with no load the motor is drawing less than a half amp, but with the motor stopped, it quickly jumps to a little over 3 amps