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Scooter Motors
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timmeh
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Joined: 20 Jul 2004
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So will one of the motors im buying still have to pully on it?

and the slighly stuffed motor will not?
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Post Wed Dec 22, 2004 9:57 pm 
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Knightrous
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I'm not selling the motors. Gears/pullies/wheels only. Motors I want Smile
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Post Wed Dec 22, 2004 9:59 pm 
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timmeh
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O ok thats fine
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Post Wed Dec 22, 2004 10:03 pm 
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Knightrous
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Well I found the problem with the motor. It's not the bearing (sounds like gravel, will get replaced) but infact when tapping the shaft, it has allowed the armature windings to shift 3mm up the shaft and just mere fractions off the bearing.

So tommorow, some adjustment hammering should move the armature back to it's original place. But chances are, knowing my luck, I'm in for another scooter motor Crying or Very sad
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Post Wed Dec 22, 2004 11:09 pm 
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Knightrous
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I fixed it Very Happy Just needed some correctional hammering. I held the windings with my hand and hit the shaft in the direction it needed to go and moved it 2mm giving the bearing breathing space and freeing up the motor once again. Works like a bought one too Cool

*note to self: If it ain't fixed, break it so you can fix it. Learning is gooood!*
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Post Thu Dec 23, 2004 10:08 am 
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timmeh
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Hahahaha learnding hahahahaha
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Post Thu Dec 23, 2004 10:43 am 
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Nick
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Arron, so what you're saying is that the entire armature can slide along the shaft when the end of the shaft is hit? What's going to happen when another spinner hits the bot along the axis of the motor shafts?

I was going to use some scooter motors in a lightweight, but now I'm worried. Perhaps the armatures can be held in place with a high strength locktite or spacers I have not taken one of the motors apart yet, how hard is it to get back together?
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Post Thu Dec 23, 2004 11:47 am 
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Knightrous
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The bearings and there locking collars generally help hold it too, but I dissassembled the motor to tap the shaft off. If your worried about them shifting when hit by a spinner, you shouldn't be using any sorta of electric motor in your robots, because they all do the samething. We've shifted the shafts in Mini EV's(300psi motors), 550's, 540's, fan motors, Scooters and even a P9000. The motors will never experince this type of treatment during battle because there is nothing hammering directly on the shaft itself.

Looking at those ThinGap motors, I think they would shift easier then most motors since they don't have resin windings around the shaft centre Wink
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Post Thu Dec 23, 2004 1:07 pm 
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Nick
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I think the armature COULD shift if the bot was hit along the motor axis by a horizontal spinner like Basilisk. not a big risk, but not impossible:

When the bot is hit, it will be accelerated sideways at many meters/sec. I think Jake guessed 10g.

The bot and all it's parts have a certain amount of inertia that requires a force to get it in motion. This force has to be transmitted to individual parts along a chain of other parts from the source of the impact.

For the armature, the path might be chassis - motor mounts - motor case - bearings - shaft - armature. SO if the armature is not well attached, it's inertia will tend to keep it in place while the shaft moves, causing a problem.

At the other end of impact, if the bot is slammed into a wall, the armature's momentum will tend to keep it moving while the rest of the bot stops, causine a shift in the other direction.

Likely? No. Possible? Definitely! just look at how many bots fail due to connectors and parts coming apart during impacts - its the exact same process.

About those Thingaps; They certainly aren't bullet proof, but the armature is very light (no iron at all) and very well attached, so this particular problem shouldn't affect it as much as a motor with a heavy iron armature. I'm more worried about over heating and brush damage.
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Post Thu Dec 23, 2004 1:46 pm 
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Knightrous
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The motor magnets will crack long before the shaft will shift in the armature, so you might want to worry about them first.
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Post Thu Dec 23, 2004 2:27 pm 
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Nick
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That's just your B&S motor, Arron Razz . Seriously, if the motor has a thick case and the magnets are well glued in (like the EV warrior and those Thingaps), then the magnets should be virtually indestructable. After all, what causes the magnets to break? It would mostly be the motor case deforming or the magnets breaking free.

The drill motors are entirely different - thin case walls and poorly held magnets make it very quite the magnets will break. even so, I can't recall anyone in Australia having that problem recently.

I don't know about the scooter motors yet since I haven't opened one. How sturdy do the magnets and casing look to you?
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Post Thu Dec 23, 2004 2:40 pm 
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Knightrous
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Magnets are generally very brittle metals, if they are mounted to ridged, thats worse then having them moving. We broke the one in our B&S motor because it fell off the bench when it was getting first put in the robot and we just epoxied the shards back together and in it went.

Tough As Nails is a 2 tonne pneumatic clamp bot that snaps shut in under 0.2sec. Pulling around 40-60G's according to Mario on impact, they have more problems with breaking magnets in the Bosch 750 motors with the glued magnets and retainer clips then the armatures moving on the shafts.

A simple way to dodge the magnet problem is to run series wound motors Cool
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Post Thu Dec 23, 2004 2:48 pm 
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Glen
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has anyone done any tests between the 200w and 300w motors, they look almost exactly the same with a 3amp increase in running current or something like that..

im pondering some 200w motors in a thwackybot but the chain reductions they sell on oately seem to have some reduction that makes them run at 300rpm ~
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Post Thu Dec 23, 2004 5:31 pm 
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Nexus
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THose Oatley sprockets are also 165mm high as well so prob not a good idea.
Am also planning a thwackbot next with scooter motors using the same setup as in KingPin but overvolting it more.
Will start a post soon as I have a name already.
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Post Thu Dec 23, 2004 5:44 pm 
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Spockie-Tech
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quote:
A simple way to dodge the magnet problem is to run series wound motors


Series Wound motors are good for spinner weapons, but they are really hard to make go backwards. At least we havent managed it reliably yet, nor has anyone else that I know of.. The second coil in series seems to generate really nasty spikes that keeps smoking controllers. Theoretically, a big diode should fix it, in practice the smoke keeps escaping..

IIRC Magnet problems on the Bosch GPA750 are quite common. I recall reading that they need a lot of prepping with magnet retaining clips, glue and welding the end-caps on to be suitable for Robot Wars use. Why anyone ever used them when the EV Warrior (GPB's) were available for a lot less money was always beyond me..
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Post Thu Dec 23, 2004 8:39 pm 
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