Time..... Mark works in Austria, & Im very busy so I have to fit robot building in amongst a lot of other things (including two jobs). It normally ends up that we get one shot a year as building takes so long.

The first Executioner was a bit of a pain because to get the massive pump & other hydraulic bits within the weight limit, we had to use an aluminium chassis. This is not easy to weld at home unless you have a really decent big MIG. Modifications have to be made in the garage, then taken somewhere to be welded with decent MIG/TIG equipment. Also, even with a regen valve, we found hydraulics too slow. Hence a petrol spinner. The other thing was battery life, the pump pulled in excess of 125amps. Battery life was a bit of a problem. Petrol engine performance doesnt drop as the fuel is used, whereas motor performance drops as the batteries run down.

I design the robot in my head as I go along, the only engineering drawings (if you can call them that), were for the spinning weapon as this had to be made on a very big lathe.