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spinning weapon advice
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timmeh
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Joined: 20 Jul 2004
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Location: Victoria


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OK

Im using bevel gears on my light weights disc so i hope it dosent stuff my motor or gears?
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Post Sun Oct 03, 2004 10:13 pm 
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Knightrous
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Got any form of clutch or device that will slip to protect the motor from brute forces?
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Post Sun Oct 03, 2004 11:01 pm 
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Nick
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If you have the space, use a belt that will slip a little. If you have the weight to spare, use big gears that can take the shocks. I.E. the gears in my Mag motor's gearbox have taken a bunch of big hits and they hardly look worn because they are big enough to take the pounding.
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Post Sun Oct 03, 2004 11:45 pm 
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timmeh
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Dont have the space for belt.

Heres what im useing they have a 15mm or 16mm bore >
http://www.hotkey.net.au/~acerules/pictures/image36.JPG

With 2x 15mm or 16mm bearings with four bolt cast iron housings"The blue ones">
http://www.hotkey.net.au/~acerules/pictures/image23.JPG
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Post Mon Oct 04, 2004 6:36 pm 
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Spockie-Tech
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Cast iron bearing housings, apart from being heavy, have often been known to crack when used on spinner shafts..

Cast Iron is strong, but brittle.. it will take large gradual loads, but a sudden shock will crack it quite easily. for a shaft that has to deal with high impacts (like a spinner), you want a softer metal that will deform, but not break.
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Post Tue Oct 05, 2004 1:59 am 
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Nick
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That little pile of goodies must weigh almost as much as your EV motor! Smile

The gears look more than big enough to handle the job, particularly if they are quality hardened ones. I see one problem though; they seem to use grub screws. In a high-impact situation, grub screws will fail pretty quickly (that's your clutch Smile ). I would be thinking about using Trantorque bushes or getting keyways cut in the gears to stop them slipping on the shafts.

If you were planning to run the small bevel gear directly on the EV motor, you could get it drilled out to 19mm and use a 8 - 19mm trantorque bush, which is handy way of adapting the small EV shaft up to a resonable size.

Brett is quite right about the cast iron - it looks strong but fractures pretty easily. The pressed steel bearings you have might last longer.
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Post Tue Oct 05, 2004 7:07 am 
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ffej
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Doesnt Nightmare use cast iron flange mounted bearings?
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Post Tue Oct 05, 2004 4:59 pm 
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Nick
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Could be, he sells them on the RMP site. I recall that the Kkeerroo's used cast iron bearings on their first bot and broke them in a match.
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Post Tue Oct 05, 2004 5:27 pm 
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timmeh
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Those gears are for in my light weight and will be bolted onto the shaft which will be normall steel bar and im using a wheel chair motor so the motor is more robust then an ev.

Yes knightmare do use the same housings and there 2 bolts myn are 4 so im hopeing ill be ok.

My main concern is breaking teeth.Has anyone herd of a bot breaking them? Confused
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Post Tue Oct 05, 2004 7:32 pm 
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kkeerroo
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Nope Nick, that wasn't my first robot. The Aggressor was my second and that was its second upgrade. The reason why the pillow block broke was because it was hit by Annihilation. It took a chip out of the top and sent a crack across it though the hole for the grease nipple (and people were wondering why I was walking arond the arena looking for my nipples).
Having looked at the cracks and the chipped area it looks like the pillow block was cast with grey cast iron, or more correctly a high carbon, low allow steel that had been quenched but not tempered make I high hardness, low strength steel not suited for impact loading. Therefore the pillow blocks of this type should be mounted with the base always at the bottom and covered so it won't be hit by blades. Actually its best used for drive train. Nightmare uses the flange mounted bearings which are more suited for weapons.
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Post Tue Oct 05, 2004 7:37 pm 
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timmeh
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Thats what im using a 4 bolt flang bearing.

I wont have to worry about other bots hitting them cos they will be inside the bot.
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Post Tue Oct 05, 2004 7:41 pm 
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Totaly_Recycled
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Sounds like you might need to use those trans torqe things that nick uses if your gears are hardened as i doubt you will be able to cut key ways in them.
Also i would stay clear of cast iron bearing houseings for shock loads i like to use mild steel as it will stretch and deform before it will actualy break. I made all of vertex's bearing mounts out of 3mm wall galvanised pipe and welded it on to flat bar for mounting i just machined it out to an interferance fit for the bearings and machined circlip grooves inside to hold the bearings from drifting out . You can als buy presed stel bearing mounts some of them a a litle thin but i havent seen any that have broken although i have replaced a few on mowers that have had the bolt holes stretched from being worked over a long period with lose bolts .

Post Tue Oct 05, 2004 10:12 pm 
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