Farmboy would have possibly beaten Kojack in the final match if it has a weapon for longer then 3.2748493 seconds

I ignored my own rules and used chains... Look where it got me! Going to use Mult V belts for the rebuild as they worked awesome for the drive train and are 1/4 the price of the chains.
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https://www.halfdonethings.com/

Wait till you see farm boys dance in slowmo
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Miles Blow - Julie Pitts
www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

quote:

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Originally posted by miles&Jules:
Wait till you see farm boys dance in slowmo

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Nice work bro, good report and good to see you were able to get some combat time onto those new gearmotors with no issues.

Glad our fight was early when my weapon was working well haha

You haven't heard the last of Das Boot! *shakes fist*
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<Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls

In anticipation of Nationals having Sportsmen class, time to finalize Farmboy 2.22!



New aluminium structure over the top, which will have polycarbonate panels bolt onto it.
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https://www.halfdonethings.com/

One of the issues FarmBoy MK2 had was that it was built in a fashion that it required assembly in a specific order and certain parts were not interchangeable. For example, to replace a drive motor, I would have to remove the whole weapon assembly, remove a front panel, the side panel and any parts bolted to those. This could be anywhere in the 15-20 min range, which is way too slow for repairing between matches. I started to have motors come loose on the gearboxes after the Zoidberg fight, however it would have taken me far too long to dismantle the robot and fix them. Luckily I lost to Kojack and I never got to the point of the drive failure.

Glen and I had a quick discussion on this as I was building the robot, but there wasn't really any time to change the design mid-build to resolve it, so I just ran with it. However, with 3 months till Nationals, this is the time to fix the problem and I have tackled the issue as follows.

MK2.1 has side panels made of 5mm 5083 aluminium instead of 10mm, this halves the weight and I no longer have to drill and tap everything!
Each panel has a pair of 'Keyholes' cut into them.

This allows the motors to be unbolted and lifted straight out the top of the robot.

The drive pulleys and support bearings can be fitted onto the robot separately to the drive motor as one unit.


Glen suggested the use of bearing cups that bolt onto the side panels instead of boring pockets and pressing the bearing in. This allows a quick removal of a bearing with just 6 bolts.


Then the wheel just bolts on as per normal.


Switching to this design allows the whole robot chassis to be water jet cut and welded. Saving some weight and a whole lot of mucking around compared to the drill n tap chassis.

The next step is to revamp the weapon assembly and look at ditching the chain drive.
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https://www.halfdonethings.com/

Cools, will probably have alot of warpage from welding that though, what about some nut strip? Then it can 100% be bolt together after cutting it out.
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www.demon50s.com - Minimoto parts
http://www.youtube.com/user/HyzerGlen - Videoooozzz

+1 on warping. Also, 5083 is relatively soft, so having that large cut-out will weaken the side considerably. I would make the frame a little wider and mount a square bearing block on the inside, with 4 larger screws going thru the frame and into the block. then the frame only needs a narrow slot for the axle and the block helps to reinforce the frame.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

Some good points on the potential warping, I might be able to address that by using stitch welding methods or event building a strong welding jig. I can't use nut strip as I do not have the space to waste for it and it's a similar situation for adding internal bearing blocks. Currently the bearings inside the bearing cups actually sit inside the boundary of the side panels, I could shrink the key holes a lot if I moved the bearings outside. However that would put all the bearing load onto the bolts and instead of the shoulder of the bearing cups.

5083 is soft, but I believe it is currently sufficient for use in sportsmens. When I start seeing it regularly bent up, I'll consider shelling out for some better grades.
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https://www.halfdonethings.com/

Also pretty compact little robot... so will be less likely to bend right?
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Miles Blow - Julie Pitts
www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

Quick shuffle in Solidworks...

I've reduced the keyhole in the side wall from 36mm to 28mm. The shoulder on the bearing cup is now gone and the bearing shell is used as the load bearing structure between the chassis and bearing cup.


The chassis is only 270x200x60, making it a very small unit. If I can find a better lifter solution, I would attempt to make it even smaller.
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https://www.halfdonethings.com/

Having similar space constraints in my full combat feather, and a similar wheelbase, I had this issue. I dealt with it by placing the threaded bar/nutstrip on the back of the machine, running the side panel past the rear panel, completely capturing it with slots in the chassis in the process. Makes it strong before it's even got any bolts in it.

http://i.imgur.com/AkLpV37.jpg
http://i.imgur.com/nYyjrAX.jpg

Also in my case I could put the bearing block actually inside the wheel. Can you hollow out the colson to do a similar thing?
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Online store - www.ranglebox.com
Pulsar and friends.

Wow Ellis that metal work looks genius.
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Miles Blow - Julie Pitts
www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

I found this the other day btw.
http://aluminium.matter.org.uk/content/media/images/stap-graph-stress-strain.gif
5083 doesn't look too bad for armour, it'll bend a whole bunch as you load it up and it yields slowly so it should absorb heaps of energy.
Dunno if those properties are what you are after for a frame though.
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Mechanical engineers build weapons, civil engineers build targets

I use the 5083 grade as it's very easy to get in 3-10mm sheets since it is commonly used for Marine applications. It might not be theoretically best on paper material to use, but it has always done the job.

In the sportsmen class, until we start getting hardcore flippers, hammers, axes and crushers, a cheap grade like 5083 is very effective.
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https://www.halfdonethings.com/