Jan 24 Update
Jan 29 Update
Feb 4 Update
Feb 7 Update
Reversible ESC
Weta Punga


God of Ugly Things!

A "Weta" is a very large insect from New Zealand http://en.wikipedia.org/wiki/Weta

One english translation of its native name is "God of Ugly things".

This then seemed a good name for our new 3lb beetleweight combat robot. It will be our first ever drum bot and its design and build will be followed on this page.

First idea was for a chassis machined from a solid block of UHMW combined with an "in-drum" brushless motor. I abandoned this design point when it became clear that the drum design was too complex for a first ever drum design. 

Next idea used big tough wheels up front and O-ring belt drive with a timing belt and brushless in-runner. Problems in making weight and the small drum size versus the width of the bot led to me abondoning this design even though it was complete in most details.

This the design I finally settled on. It used the Drum design from the big wheled version aboved but with a more conventional chassis.

Chassis side rails are 1/2" UHMW. Top and bottom panels are 2mm thick carbon fibre and the rear and wheel protection will be from 1/8" UHMW.

This is the intended weapon motor ESC.  It reversible and with a 35A rating should be ideal.

http://www.unitedhobbies.com/hobbycity/sto re/uh_viewItem.asp?idProduct=7186

I've ordered two but they have been on backorder since early December :( If it does not arrive in time I'll use a 40A ESC similar to that used on "Pure Dead Brilliant".

And this is the planned In-runner, a Turnigy  2835 with a Kv of 3900.

http://www.unitedhobbies.com/hobbycity/sto re/uh_viewItem.asp?idProduct=4200

Planned drive is B16 motors, Daves Hubs and 3" LiteFlite wheels.

I'll use the small 3-9 banebots ESCs for the drive and a 1050mAH LiPo.

Most parts are in and build will start with the making of a aluminium template of the side so that I can quickly rout out several sets.

1/19/2010 Update

Heard today that the 35A reversible weapon ESCs are back in stock and mine should be here in about two weeks :)  I also ordered an 18A one for use in an upcoming Antweight.

I have also designed a small mounting plate that will allow easy mounting of the b16 motors.  These motors use tiny M2 screws combined with a double D front face both of which are not ideal for a easy build.  The plate will be watercut from 1/16" Al and then countersunk to suit the M2 and #4 screws I plan to use to attach it to the UHMW side rails.

I plan to also make this part available on the kitbots website....price to be announced.

Machining of the AL pattern for the sides is about 30% done. I have also added connectors to all my 3-9 Banebots drive ESCs so that they can be quickly replaced and also interchangeable with those on "Pure Dead Brilliant"

1/22/2010 Update 

 WARNING:  a wood router is dangerous tool and great care must be taken with its use.  The bits are extremely sharp and thick leather gloves MUST be used when handling them at all times!

I finished the pattern for the sides of the bot.  Its machined out of 1/4" thick Al.  I mounted it with woodscrews to the same 2" thick block of plywood that I use as a jig for the PDB2 kits and drilled a couple of 1/2" holes to give the router an easy start.

I then routed a good clearance right around thge part and in the large centre hole.  This is so when I'm routing the plastic parts I'm not routing wood at the same time. I used a 1/2" pattern bit which has a 1/2" ball bearing at the top  that can follow the profile of the Pattern.

Four blanks were then cut out using a jigsaw.  the blamks are slightly larger than the pattern.

A blank is then placed between the pattern and the jig and the pattern is then screwed back onto the jig.

In a very little time one can make as many parts as you need.  One part got a little chewed up when the bit moved in the router but its still usable.  I have the two sides I need plus a couple of spares. The sides need a little more machining but the router has done the vast majority of the work.

Reminder.....I was not kidding about the danger of using a router. Wear safety glasses and always use leather glove when handling the bits.  I cut myself  so learn from my mistakes!