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Hmm, that will defeat the purpose of a light and compact setup if I had to use herringbone gears. I could maybe use helical gears and thrust bearings...but probably its better to keep it simple and do as you said...go with straight gears, any recommendations on who sells loose gears at a reasonable price, preferably within the EU not the States?Quote:
Originally Posted by maddox10
Technobots has a suitable range of gears, and are very dependable.
Christmas shopping time!
Just need some advice before I start ordering stuff... I'm about to order gears for the gearboxes, motors and escs.
The motors I'm going for are these:
http://www.hobbyking.com/hobbyking/s...dproduct=16231
These spin at around 13500rpm on 4s. The diameter of the wheel/track is 80mm, I'm thinking of gearing it down with a 12:1 ratio.
Did some research of available gears and I'm looking at two stages of 6:1 using 5mm wide 0.7mod gears with 10 and 60 teeth.
Any suggestions if this is suitable and strong enough for the above motor?
The NTM motors have a lot of torque, I would opt for mod 1 gears. Z12 to Z 36/Z12 to Z48.
The 12/36 double gear is one you can buy at www.Conrad.com , order number 240320 - 62
, making life easier.
Two 6:1 stages makes for 36:1, not 12:1. Stage ratios are multiplied to get the overall reduction. That setup would get you a bit over 3mph!
Mod .7 sounds a bit small to me (roughly the same as what's in a drill gearbox), and I'd be even more cautious at just 5mm wide. I'd expect to use mod 1, 10mm wide, or similar.
How silly of me! You're right! This will make my life much easier as I can select smaller gears with a larger modulus making the whole gearbox smaller.Quote:
Originally Posted by Ellis
Thanks to both of you, spared me a log of grief ;)
Will have a look at Conrad tomorrow Mario, hope they have decent prices as the gears I found aren't exactly cheap!
Had a good look at Conrad and found the same items for a lower price from the UK http://www.rapidonline.com
Going for 10 and 35 teeth gears with two stages of 3.5:1 for a final drive of 12.25...that will fit in the space I got, the 48T gears will be too large and will require quite a lot of work to fit in.
I estimate the weight of the motor and gearbox to be around 340 gr each, that's a weight saving of 110 gr over my current setup...I desperately need to shed off weight!
Christmas presents finally arrived, slightly belated but that doesn't matter now!
Been doing some sketches for the gearbox in the meantime, I'll upload them and as this is my first attempt to building one please feel free to point out any flaws etc which can be noticed
Attachment 4228
Gearbox details:
2 stages with 10t and 35t mod1 gears.
Gears interference fit on shaft.
Shaft material: chrom-vanadium (a 1/4" drive extension turned down to size)
Bearings: MR126 ZZ 6 X 12 X 4Mm, 6700 ZZ 10 X 15 X 4Mm
Side plates 7075t6 Aluminium 64x41x4mm
Grease : Rocol Aerospec100
The gearbox output shaft will bear no side loads as the drive wheel is supported by its own bearings.
Attachment 4229
Attachment 4230
I'm confused as to where all the gears are mounted, presumably the first gear is attached to the output shaft of the motor, the second 2 gears are on a separate shaft both attached to te shaft with a grub screw so they rotate at the same speed. Then I don't get where the last gear is connected? Is it on a separate shaft inline with the motor's shaft but only supported on one end?