Most people use a removable XT60 or XT90 plug with a wire link soldered across it. Some people make their own switches by 3D printing a frame with two copper plates in it and a bolt that ca be driven in to connect them. Some people use whyachi switches, but these are pretty expensive.
Sun Apr 09, 2017 9:24 am
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
The XT90 link is the easiest option, with the female side glued into a mounting block. I could print you a base in polycarbonate if you need it. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Sun Apr 09, 2017 9:31 am
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
That sounds like a good idea...
Question: what do you usually do before a match? (do you open the top cover to connect the link or do you just press down on it?)
Sun Apr 09, 2017 9:08 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
The fine print in the rules says that the power switch or link must be accessible without tools so you have to be able to get at the switch without taking all the screws out of the top cover. Having a sliding or rotating cover what is finger operated is fine. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Sun Apr 09, 2017 9:18 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
The more I think about it... How do you press down something like a link onto a piece of wire, when both of them are not really rigid?
Sun Apr 09, 2017 9:25 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
I have the socket of the XT90 glued into a printed block that also has screw mounting holes to keep it firmly in position. The plug has a printed back shell for added grip but most people just put heat-shrink tube or tape around the back of the plug. Its positioned high enough that the back of the plug is level with the top cover and I can just reach in through a cut-out to insert and remove the plug.
The idea is that the link is completely removed from the bot so that it can't be accidentally turned on in the pits and its easy for arena marshals to see if the bot is active or not. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Sun Apr 09, 2017 9:37 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
Ah I see. Thanks Nick.
Sun Apr 09, 2017 10:02 pm
shakesc
Joined: 14 May 2012
Posts: 62
Location: UK
I use a XT90 link on my bot
I line it up then simply use a screwdriver to push home
Mon Apr 10, 2017 3:51 am
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
Just found out that ordering those parts from Taobao probably isn't a good idea, so I sorta changed my mind on how the chassis will be machined and added round corners to the plates.
So... any suggestions on machine shop choices?
Thu Apr 13, 2017 4:00 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
I also heard that a number of Australian featherweights are going (or coming) to China recently. With the info I got from chatting with the builders in China I am sure that this will be a big one.
Thu Apr 13, 2017 4:06 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
Learned a lot from you guys during designing, and I came up with a bot that's intended to be cheaper to make (all panels are intended to be lasercut and drilled). It still has that 5kw weapon power though. Since in my opinion it looks a bit ugly, I'm gonna call it Contraption IIC.
Sun Apr 16, 2017 12:45 am
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
Update: Sorry that I didn't explain this in the previous post. Although I think all parts are possible to be made in the previous design, it is still a bit complicated to make as said by a few of my friends even with the additional round angles making all the parts able to be done by milling.
The new design is meant to be only laser cut, so no pockets will be present, only through holes. My new weight saving strategy would be a cluster of through holes with thin plastic cover glued onto the area with the holes so that nothing falls out.
I also changed the spinner to a simple disc spinner so that I don't have to find the tubes anymore. Another problem with the old design was that I needed to do extensive machining after I get the pulley to have the countersunk holes and a pocket for the thrust bearing. In the new version bolt heads and the thrust bearing stick out of the pulley so I only have to do through holes on the pulley.
The old wedge/front armor was a two-piece design where there's a front armor plate and there's a wedge plate(blade). The new front armor is also the front wedge, which I think will reduce cost.
With all that said I would certainly hear what you guys think of this new version, please feel free to comment.
Mon Apr 17, 2017 9:27 pm
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
Update: I quickly found out that I will have to mill a pocket on the back armor because of the weight distribution is not optimal. (I tried to go for the Touro approach, having the COM just ahead of the wheels so that there's not a whole lot of pressure and resistance on the wedge to affect driving.) Good news is that the shapes of the all the parts are now much simpler.
Mon Apr 17, 2017 11:24 pm
Nick Experienced Roboteer
Joined: 16 Jun 2004
Posts: 11802
Location: Sydney, NSW
So there is no side armour in this version? It will make turning better but exposed wheels don't last long if there are any other spinners in the competition. _________________ Australian 2015 Featherweight champion
UK 2016 Gladiator champion
Tue Apr 18, 2017 8:31 am
MoonSet416
Joined: 25 Sep 2016
Posts: 436
Location: Sydney
It actually has a side armor, I added the model after the last post.
However, I realized that I didn't do the torque calculations correctly, and the bot will tilt up at full throttle. (I was assuming the forward force was acting on the axis, but it should really be on the bottom of the wheel.) As a result, this version will be scrapped, and I will probably be working on making my last version easier to make.
EDIT: Some of the features in this version will be used, such as through hole lightening cuts, and the small side armor which covers only a part of the side.
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