building a drum spinner

hi,
i am still in the process of building my first robot (trax) but am starteing to plan for my next robot, a drum spinner. i am going to order 20mm thick hdpe plastic off direct plastics for the walls which i will screw onto an aluminium base plate. to power the drum i will use speed 900s and argos drill motors for the wheels. Just a few questions:
-where is the best place to buy speed 900s?
-can i use the robochalenge 'battle switch' to control the drum, and does it feture reversing and does it work with dc?
-if not what should i use?
-i don't want to have a bar going all the way across te drum, what do other people do?
-i considered sandwiching angle grinder disks (4 or 5) imbetwween hdpe rod(90cm diameter), would this be effective?
- and finally could i use one of these batteries(link bellow) for the speed 900s and one for the drive motors? would i be better to buy new?
viewtopic.php?f=166&t=3989

No replies saying don't do this yet, finish your first then move from there, spinner are dangerous and you should build an axe bot etc.
Thanks
Max :lol:

-i considered sandwiching angle grinder disks (4 or 5) imbetwween hdpe rod(90cm diameter), would this be effective?

see topic: viewtopic.php?f=111&t=4035

Hey,
Just looked at price of speed 900s and found out how expensive they are! Are there better (cheaper) places to get them than Hobby lobby or are there cheaper alternatives eg. Car fan motors? Also, what kind of gear ratio do I need to spin the drum?

Car fan motor will be a bit cheaper but heavier.
Battle switch would have to be modified with a larger relay for either a fan motor or speed 900's, if you wanted a simple on/off.
As with other people on the forum I think it'd be better if you finish your first machine before starting another!

car fan motor will be alot cheaper if you buy one from a scrapyard

You could get away with a drill motor if you gear it right.

A drum is best made with a tube of steel 3 or 4 inches in diameter with teeth welded to the outside. Use Nylon instead of HDPE for the bulkheads. A battle switch will not be enough to switch the motor on and off. You will need to use something with a higher current handling capacity. I have used 40A car relays in the past but would recommend a 100A relay from jaycar electronics.

The battleswitch doesn't reverse and will work with dc current.

The best design which works with all the current drums is to run a solid shaft through the middle and have bearings set into the end of the drum.

Grinding discs would not work.

Those nicad packs should work fine.

Now for the important bit, FINISH YOUR FIRST BOT AND GET IT RUNNING WELL!!!! then look at other bots.

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Originally Posted by typhoon_driver

You could get away with a drill motor if you gear it right.

A drum is best made with a tube of steel 3 or 4 inches in diameter with teeth welded to the outside. Use Nylon instead of HDPE for the bulkheads. A battle switch will not be enough to switch the motor on and off. You will need to use something with a higher current handling capacity. I have used 40A car relays in the past but would recommend a 100A relay from jaycar electronics.

The battleswitch doesn't reverse and will work with dc current.

The best design which works with all the current drums is to run a solid shaft through the middle and have bearings set into the end of the drum.

Grinding discs would not work.

Those nicad packs should work fine.

Now for the important bit, FINISH YOUR FIRST BOT AND GET IT RUNNING WELL!!!! then look at other bots.

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what kind of gearing would you need for a drill motor powered drum spinner?

A drill motor typically does around the 18 to 20k mark (with the gearbox removed of course) so you would need gearing of around 6:1 to bring it down to a point where the drill motor could quickly spin up the drum (it's always a balance between top speed and spin up time).

what sort of rpm could you get from that gear ratio?

around 3k

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Originally Posted by Hard Time

around 3k

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sounds like a good speed, and at only £10 a pop, even if it lasts for 6 fights, thats still great

you would have to use belts or chain to get that gear ratio.
I would love to have a drum spinner for not very much.

i think a drum spinner just got a lot more possible for me :)

same!
BTW Matt are you going to worthing?

if thats the September one then ill possible go with ReAvenger, gives me plenty of time to get it ready :)

are you?

yeah, we can battle our upgraded robots

ill have a 1vs1 battle with you after one of the shows if we can?

That'll be good to see my robot thrash yours!

may i join in in the fight :rofl: i think i will use my normal tactics; trundle around for about 20 seconds, get link knocked out, spend rest of fight upsidedown in the corner

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Originally Posted by Hard Time

That'll be good to see my robot thrash yours!

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you have 4wd, but i have claws :)

and harry, you could join in if you want? i can have a 4kg box to play with when ive thrashed L.A.S.E.R. :)

Sure Harry, I'll get my friend to join in.
PS I'll bring the 2mm HDPE to Worthing

Mine has a lifter beat that!
and it will push you around.

no more 4kg for me, its about 6.5kg atm without weapon!

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Originally Posted by Hard Time

Mine has a lifter beat that!
and it will push you around.

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ILL STILL HAVE YA :lol:

Which ever of you whether it be Matt or Harry buys Daiske you can run that as part of a cluster bot with Harrys 6.5kg machine, would still be will within the limit :D .

I have a fealing that mine is overweight :(. Send it to weight watchers!

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Originally Posted by Anttazz

Which ever of you whether it be Matt or Harry buys Daiske you can run that as part of a cluster bot with Harrys 6.5kg machine, would still be will within the limit :D .

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*goes to ring team mate*

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Originally Posted by Hard Time

I have a fealing that mine is overweight :(. Send it to weight watchers!

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.........fat git! :lol:

mine is the opposite, in theory it will be underweight :)

yeah if any body wants a partner for a cluster bot, drop me a line :wink:

The plan with Daiske was to add 4WD and an electric lifter and even then I doubt it will be much over 7kg.

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Originally Posted by harry hills

yeah if any body wants a partner for a cluster bot, drop me a line :wink:

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:rofl:

if your bot can come in about 1kg then I would :rofl:

Might need some helium balloons for that to happen.

I think a pair of drill motors weight about 400g each :)

i know, 2 drills, 2 reeealy small batterys, 10mm thick armour all round, stainless steel base and alumium front (plus escs) acem to 4.1kg :shock:

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Originally Posted by harry hills

i know, 2 drills, 2 reeealy small batterys, 10mm thick armour all round, stainless steel base and alumium front (plus escs) acem to 4.1kg :shock:

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how long would your batteries last?

they survived a day of white boards, they were 2800mah

Daiske is 4.5kg or so and the 7.2v 4300mAh batteries are the heaviest thing in there, they lasted for testing, 4 fights at the champs, and a fight back home without needing charged :D

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Originally Posted by typhoon_driver

I have used 40A car relays in the past.

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What is that?
Ps. Please can you get back on subject rather than discussing some private fight?

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Originally Posted by Max

Quote:

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Originally Posted by typhoon_driver

I have used 40A car relays in the past.

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What is that?
Ps. Please can you get back on subject rather than discussing some private fight?

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its at en event! :lol:

and anyway, he just knows I would trash him :rofl: