ok would 2.5mm or 3mm be better for the shell, and what would be a good way to mount the bearing blocks to the base

Use the thickest steel you can without going over weight - I know that isn't too helpful but you will need to use rhino to figure out the weight of the shell and see what's possible. If you run over weight, use thinner steel on the top and thicker on the sides, which get most of the beating.

You could use an M8 screw in each corner of the bearing block to hold it to the frame. My experience with spinning weapons is that you want the bearings to be rigid and the mount to the frame to be even stronger, otherwise an impact will bend the bar up into the frame and the bot will damage itself.
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

That is much better.

If your carefull with the design you can get away with 3 mm. But you will need to use the weight fetures in your cad program to get it correct.

Still some changes can be made.

First/ The nose, I would move that back until it was hard against the bearing block.

This will be a weight saver and you will also be able to bolt the front of the bot to the bearing block as well as the bottom.

Second/ The weapon motor. A trick to lower it.

Drop the height of the motor so the the center part is through the base plat. (will need to cut a hole in the base plat for the motor to fit.)

Remember you have a weapon that will help protect it.

This should allow you to drop the motor about 5 mm. In turn reduce the height of your robot by 5 mm, giving a weight saving of (guessing here) around 500g

third/ mounting bearing block

For mounting the bearing block I would personly use 4 M8 Cap screws in the base and 2 - 4 M6 in the front for extra support.
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It's all about the destruction.

ok sweet i already dropped the motor down on the cad and on rhino how do u use the weight feature, im still only getting the hang of it
ill take the front bak to the bearing block aswell thats a good idea,
for attaching the pulleys and the weapon to the shaft how would i do that i have a few ideas but dont really think they will work

There are acouple of ways of doing it.

1. Key way with grub screw.

2. a Shaftloc. this is a unit the will lock to the shaft and pully.

3. shaft coupling

4. 680 Locktite. this is what I used to lock a hub for the weapon on 'Little Brute'

there are some other methodes just not comeing to me at the moment.
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It's all about the destruction.

does that look ok

Its looking better every day

If you go with base welded to the sides, you will need to leave room at the front bottom edge of the bearing block for the weld bead. Adding a 45 deg. angle across that edge of the block will do the trick; you will need to experiment to find the what size is needed to clear the welding. If you go with a flat base and removable top ' sides then you will not need to worry about that.

The only way I know to mount a pulley to that particular motor is to do it like the original fan - screws through the face of the pulley & into the flange attached to the motor shaft. The pulleys you have are too small to use the existing M5 holes so you will need to drill & tap three new ones.

Mounting the pulley on the weapon shaft has more options. I found the Locktite 690 (that Ajax mentioned) sucked unless the load was low or there was an extra locking method.

The keyway method is an engineering classic. You can get most types of pulley with a key already cut and you can also buy shafts with a key already cut. The Robot Marketplace has both and is easy to deal with. The only problem I see with that is that most pre-keyed shaft is made of quite soft steel, which might be an issue down where the bar meets the shaft.

A shaft lock like the ones sold by Trantorque or MAV use friction rather than a key. I really like them but for a 20mm shaft, their OD will be something like 30mm and you will need a much bigger pulley to fit it in - I don't think you have the room.

Some brands of pulley have a built-in shaft lock which saves room. I have one with a 3/4" bore and a 3" diameter, so that style would just about fit. unfortunately, they only come in steel and it is really heavy
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

I would rearrange drives, electronics and batteries to put more weight on drive wheels, I like a well-balanced bot.

quote:

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Originally posted by Nick:
Mounting the pulley on the weapon shaft has more options. I found the Locktite 690 (that Ajax mentioned) sucked unless the load was low or there was an extra locking method.

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quote:

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Originally posted by From Loctite web site:
680 Retaining Compound - Gap Filling

A high strength, room temperature curing adhesive used to join fitted cylindrical parts. It fixtures in just 10 minutes and provides a shear strength of 4000 psi on steel after 24 hours. Capable of filling gaps up to 0.2mm (0.008"), product 680 can reduce costs by allowing relaxed machining tolerances and replacing clamp rings, set screws and snap rings.

Applications
Gears, wheels, pulleys, cams, collars, flywheels, sprockets, and rotor to shafts.

Specifications
NSF61
Related Products

Loctite 7070 ODC-Free Cleaner and Degreaser

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i agree with rotwang
weight should be on the drive wheels as much as possible, otherwise you will be skidding all around the place and it'll be a biach to drive.
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Mechanical engineers build weapons, civil engineers build targets

One other thing to possibly think about is rather than start from a base plate turn it upside down and have the heavy strong permanently attached panel as the top.

Load batteries and maintenance access from underneath.

Overseas comps use arena hazards, Kill saws spikes, flame pits etc, So far that hasn’t happened locally.So strong bottom Armour is very necessary overseas but not here.

We prefer a contest between the bots and the bots work well enough these days that its not really necessary to jazz up the show with those sort of gimmicks.

Very few bots attack from underneath, More from above.

There is currently no local bot that flips and then attacks from above and it would be a bad idea to try and build one because a lot of bots are still built with thick bottom Armour and thin top Armour.

Elanore is a good example of this idea.

Ummm, Eleanor has everything attached to its base plate and then has the shell bolted on top. Devastator has everything bolted to the shell and no base plate.

Ok maybe I should of waited to see Elanore in RL. OK Rat, and Devastator

Kang was built like that also and had the same motor, mounted to the top. The downside of that concept for this bot is that the weapon block is then mounted at the far end (the top) and the front. As I found out in Jolt, this puts a huge extra strain on the mounts as the moment of leverage between the weapon and the mounts is much longer. I had to go up to 10mm aluminium to stop the frame bending and 3mm steel will probably bend too.

If you want to make the bot more balanced, try placing the batteries behind the drill motors in a long thin pack and making the front pointier.

Have you thought about how the bar will be mounted to the shaft?
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Australian 2015 Featherweight champion
UK 2016 Gladiator champion

wat i was thinking of doing is most people try to attack from behind or where they dont have a weapon so ill make the front part of the shell with thinner metal and make the bak a bit thicker, and also put some metal at the bak and side to hide the wheels so it make it harder for a wedge and a flipper to get under the bak of me and flip me over