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Knightrous
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Spur Gears

I've got a few questions about spur gears.

I'm looking at making my own gearboxes for a pair of Astro 40's. I've decided I want a 10:1 ratio, but I'm in a bit of a pickle about which size spur gears to get for this reduction box.

Here's what I've come up with so far:

Stage 1: 0.75 Mod - 10T gear mated to a 50T gear
Stage 2: 1 Mod - 10T gear mated to a 20T gear

I'm just not sure if the gearbox will survive the torque loading of the Astro's (2.7Nm Stall). The 0.75 Mod gears are rated according to my HPC gear book to 4.5Nm with the case hardened gears and the 1 Mod gears are rated to 12Nm with case hardened gears. I'm iffy about how the gears will go, I doubt the motors will ever get to produce the full 27Nm stall in combat conditions (Unless something wedges itself into the gears) so I'm wanting some oppinions.

Also, if anyone knows a cheaper place to get the gears I'm looking for, please post (Not TEA Transmissions, those guys are rip off merchants).

I'm looking at a cost of $150 in gears alone if I head down this path, so I'd like to get some feed back before I strip the first stage and blow $$$...
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Post Sat May 13, 2006 7:12 pm 
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Knightrous
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I've had a bit of a rethink...

Looking at using a full train of 1 Mod gears using 10T & 32T gears for a dual 3.2:1 ratios for a total of 10.24:1

They should survive the torque... I hope Confused
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Post Sat May 13, 2006 8:36 pm 
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Daniel
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What are the gearboxes for? Two wheel drive or weapon?
What are the expected loads? Shock loading?
What are the length of the teeth you are wanting to use? Tooth contact area?
What are the gears going to be made out of? Case hardened steel?
Can you afford to replace burnt out Astroflights?

We need more information to answer questions, you noob. Wink

Post Sun May 14, 2006 9:16 am 
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Knightrous
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quote:

What are the gearboxes for? Two wheel drive or weapon?
What are the expected loads? Shock loading?
What are the length of the teeth you are wanting to use? Tooth contact area?
What are the gears going to be made out of? Case hardened steel?
Can you afford to replace burnt out Astroflights?



4WD Drive
Loads of load, it's drive
1 Mod gears, what ever the tooth length is... 8mm wide gears. IF you want the dia's with PCD, I can provide that
Can't you read? I said case hardened Laughing
Probably not, but the plan isn' t to burn any out Razz

If you want me to shift to noob mode, no prb.

Danielle, how make gerboxes w00t? I got like $.04 and a cordlezz dril, how make l337? Wink
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Post Sun May 14, 2006 10:06 am 
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Glen
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quote:
Danielle, how make gerboxes w00t? I got like $.04 and a cordlezz dril, how make l337?


lol simple take a dewalt gearbox and adapt an astroflight to it the astros only have a 1.5mm bigger shaft... n00b XD
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Post Sun May 14, 2006 10:25 am 
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Knightrous
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Dewalts Laughing Now that's a laugh Laughing
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Post Sun May 14, 2006 11:19 am 
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andrew



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yeah well just get around and build something already darn it

Gosh been like 2-3 years hasnt it
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Post Sun May 14, 2006 1:55 pm 
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Knightrous
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Trying to build something new for a change. Al my general designs are Kinetic based or Brick based. Aiming for something in the neutral this time. A weapon with some moderate armour.

Anyone got some useful information, or have I started another spam thread? Even some links to Aussie based gear suppliers would be good thanks.
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Post Sun May 14, 2006 4:07 pm 
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dyrodium
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Aaron you might like to look through the minibearings massive online database. Most of their things are outrageously expensive, but some are lower in price, and may have something you need. I might get some timing belts and pully's from them, the economy style ones are reasonably priced. Smile
http://www.minibearings.com.au/
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Post Sun May 14, 2006 4:35 pm 
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Knightrous
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Thanks for the link Angus. Prices arn't too bad, I worked out getting 4 x 14T & 4 x 46T is only $150, which is cheaper then buying them from HPC (Due to £ conversion and shipping). I'll tinker around some more, keep saving cash up and may well invest in those gears.
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Post Sun May 14, 2006 4:52 pm 
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Nick
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Why not get some info on the Whyachi TWA40 gearboxes? They are a similar ratio and I hear they never break gears. Making your own gearboxes will be a challenge; Perhaps it would be easier to use chain or belt reduction? They can take quite a bit of space, but you can put the motors where ever you like and belt drive can be lighter than gears if you use aluminium timing gears. An even better arrangemant would be to use 1st stage gear reduction and a 2nd stage belt, combining transmission out to the wheels. A single stage gearbox is way easier to construct; you can use something like this NPC design:




The back plate of this gearbox could easily be a frame member. For 4 wheel drive, you will be using chains or belts to the second set of wheels anyway.

EDIT: if you take Glen's advice, I can trade you some DeWalts for the Astros Razz
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Post Sun May 14, 2006 5:04 pm 
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Knightrous
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I have allowed myself 80mm x 50mm x 50mm to make my reduction box. The TW gearboxes (I had that one open a lot of time Wink) I noticed are approx 1 MOD or 1.25 MOD gears and that is why I based my decision on 1 MOD gears.

I'm also considering another idea from Andrew A, some custom AndrewMOD using only the first stage from the DSE 18v drills... I would have to make up a new carrier on the second stage, but it would be an effective gearbox when completed, and only a fraction bigger then a normal gearbox.

To be honest, I shun the Dewalts. Having seen Singularity loose brushes out of them and Glen cooking his batteries... I don't think it's good buying a $200 motor and gearbox combination if you have to put a zip tie on the brushes to hold them in... Confused

To connect the front wheels to the rear wheels, I'll use light timing belts and nylon timing pullies, but that's another saga...
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Post Sun May 14, 2006 5:17 pm 
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Nick
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I have some spare nylon timing pullies you might be interested in...
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Post Sun May 14, 2006 5:35 pm 
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Knightrous
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Mmm.. Let me work out the gearbox situation first, then I'll hunt the next part of it.
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Post Sun May 14, 2006 5:40 pm 
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Glen
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lol i wouldnt hype the astros up either nick has one with a shattered brush housing just from it being mailed.
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Post Sun May 14, 2006 6:22 pm 
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