Monday, May 14, 2012


I have just sold my tracked robot on eBay. While driving it around was eventful, (sorry for running over your flowers Deb) the actual fun for me lied in the design and build. A while ago I came across these surplus hospital carts on Craigslist and I thought those would make an interesting robot base.

This is the cart in its stock configuration. The base holds two 17ah 12v batteries and all the electronics.  The top has a keyboard drawer and mouse. The mast has a linear actuator in it to allow height adjustment of the table height.

 Unfortunately the monitor/computer was trashed but all of the internal wiring was there along with the two dead batteries. ( I gutted it all anyways.)  I knew from the start I was going to put two wheelchair motors on it, but that as far as it went for a while.
I tried to reuse the electronics but the company that made these is long gone and no schematics are available. 

Well lately I have been rather busy, but I finally figured how to get all the components into the base. I gutted the inside of the original battery case and removed all cast in mounts at stiffeners. I then cut an aluminum plate for the bottom, then set the batteries in and welded sides onto it to enclose them. I then mounted the motherboard to the back of the aluminum enclosure with the sides holding the CPU power supply and the motor drivers.

 Here are the gearboxes without the motors on them. 3/8" aluminum welded to the stock frame. Motors, wheels and gearboxes are from a powered wheelchair.

Monday, January 30, 2012

Snow blower track robot base

I have always wanted to build a tracked robot, not that I don't like ones with wheels, I just think that the tracks make it look a little better. There are many types of tracks out there, from little ones on toys to larger ones on construction equipment. However, I have found that the best, medium size tracks are found on snow blowers.

I had purchased two sets of track,s both were on complete snow blowers. One ran (125 dollars) the other one was disassembled (65 dollars,) but the tracks were in good shape and complete.

I'm using two 350 watt motors from wheel chairs as they already have built in gear reduction.

Here is what a motor gearbox looks like inside with all the grease cleaned out.
The spring on the larger shaft was for the lever to disengage the gear by sliding it over on the shaft so the wheels can rotate freely.
I have removed the lever and the decided to not use the cover also as it will reduce the overall height of the motor/gearbox for more ground clearance. My new aluminum chassis uses a single aluminum plate the mount for the motors so that serves as the gearbox cover also.
Future plans include some type of two speed gearbox the the base can really move but I am still doing the CAD work and researching the gears as I would like to get it to fit into the existing gearbox.

My first chassis design was from mild steel because I could cut and weld it easily, and it was my first frame and I wasn't quite sure how I wanted it. The two 17 Ah, 12v batteries were mounted in the middle because my first thought was to keep the base a narrow as possible but as you can see in the next picture that did not provide alot of ground clearance.

In this picture the flat aluminum plate that ties the two motors together also serves
as the cover for the gearboxes. The stock cover was about 3/4" thick and had the manual lever sticking out of it.

Thursday, October 13, 2011

Micro MIll

I recently picked up this MicroMark mill. I got it off craigslist (Chicago) with a whole bunch of tooling. The cart / stand is from a hospital that also came from Craig's list.

The mill came with a DRO on the 3 axis's but the goofy rubber plugs that plug into the scales were so loose that the readout would not work half the time.

So, like  any other enthusiast I just cut them off and soldered the wires directly to the circuit board.

Once they were soldered  I assembled the units back together and I put some silicon in the pockets to seal them.

Tuesday, October 4, 2011

Telepresence Robot

I'm always on the look out for new thing to use in building my robots or to make into robots. Recently I was scouring the local electronics recyclers and came across these hospital computer carts,  And the first thing that came to mind was that they would be a great start for a Telepresence Robot.

Has 17 inch monitor (12 vdc) with motherboard
Keyboard drawer
Battery and charger in base (Dead battery)
The center post also adjust up and down to vary the height.

My plan is to replace the rear caster with  drive wheels to move it around.