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Old Nov 21, 2004, 01:02 PM
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I had some links to watch gear suppliers in another industry besides watch makers. Scapbooks come to mind. You don't know what you will get with the order but have gotten some parts to make 6:1 gearboxes as well as lower ratios.

My first watch gear gearbox turned out a flop. I used a balsa spacer and wrapped with thread this offset the spur gear. It would run but not smooth plus the motor heated up using a 1.5" prop. I might have even damaged the motor as it stalled the first hookup. I think I'll go to the drawing board with the measurements I have and see if that works out. If it does'nt I can always open up the spur slot as in Dave Wulf's technique.

On another note not to change the subject but In one of David Dewitt's posts in the DIYIR thread he posts a picture of a drawing of his hinging. In that photo there's what looks like a square motor magnet housing. It was a few posts after his 1.5g plane posts with the notched motor can. Seeing that along with Dave's light plane got me thinking. I was wondering if you could make a square can like the HiLine Minbi6 or old stomper motors, and use small N50 magnets with the coreless motor coils? Maybe the coiless motor coils are more suited to having the magnet on the inside but seems like the square motor would be the easiest route to a lighter than the 4mm motors diy homemade motor.

Billy
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Old Nov 21, 2004, 06:43 PM
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Dave, I use them for small size.
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Old Nov 21, 2004, 07:15 PM
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Dave
I missed your post somehow.
Depends on which watch gears you use but probably most are lighter than the .2mod plastic gears only because the watch gears are so thin. In the end if you lightened the .2mod gears you probably would not be able to tell a whole lot of difference in weight if the same materials are used for axle, bushings, and supports. Like Graham I'm using them because they are small. Plus the watch gears will for sure be lighter than the .25 or .3 mod gears I have. Might be able to make some bit gearboxes almost as light if the bit gears are thinned.

Billy
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Old Nov 21, 2004, 07:54 PM
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http://www.clockworks.com/wparts.html

I bought two of the 1/4lb packs and spend about two hours solid trying to sort through them, I never did quite finish as it was literally sending me insane. Lots of gears, some brass, some steel. Really nice stuff although there were quite a few completely useless bits as well.

Moo ha ha

Graham

p.s. Thanks to Ralph Bradley for the link!
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Old Nov 21, 2004, 08:19 PM
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Here's the other link from Ralph.
http://scrappinfools.safeshopper.com/
1 oz of watch parts for $0.90 but some of the 1oz grab bags may not have useable gears in them. I would imagine if you ordered $10 worth you will probaby get some good gears. They will not pick through the parts and just send gears either I allready asked.
Graham you are not crazy the small parts are hahahah.

Billy
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Old Nov 22, 2004, 12:20 AM
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Ok
I built a gearbox with 2 ply uprights. It's working better than the balsa spacer.
I done the math and the pinion seems to be .125 mod. The spur turned out to be .124...something or another mod so I calculated the distance using .125mod figuring(vernier complications) the spur was probably .125mod. Well I think it would have been almost a perfect fit but the spacer I used for the spur was wire insulation resulting in a offset so the gear hangs bit in one spot. If there was a 1/16th of a hair more space between the gears I think it would be perfect. I do think it would be a bit fiddly to make a gearbox like Dave W posted with this size gears. It's fiddly enough with just the 2 uprights. How much mesh allow distance should you use for .125mod gears? Didel and Carl Martin have a figure for .3mod gears how did they figure it? I know Carl came to his figure by having a laser cutter attached at the hip.

Graham
Is your pinion 1.5mm and 10 teeth?

Billy

[edit added some pics(appologies for excessive blurriness moved pc and theres no lamp closeby yet)]
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Old Nov 22, 2004, 11:32 AM
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Hi guys,

I just finished off my gearbox today. It tips the scales at 0.285mg w/o prop, the motor w/o gears, cf prop shaft or nylon bearings was 0.27g. I replaced the motor shaft with hypo tube as per Bob Bailey's technique, and used a 0.7mm 8tooth pinion and 4.5mm 60 tooth spur. Another 10 or 20mg could be saved by using less glue, trimming the endbell, changing wires etc. It runs almost silently, but I can feel friction in the bearings and gear mesh.

Ben

EDIT:: New pics
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Old Nov 22, 2004, 01:01 PM
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What do you guys do about the motor axle slipping out?
There is too much play in the axle the play is wider then the pinion and if it slips all the way out then the pinion slips of the spur. I imagine you could pull it most of the way out then glue that plastic retainer on right?

I allready accidentally pulled the endcap off and broke one of the wires.
Not sure if the endcap is back on correct but measured 140 -150 ma current at 3.85V with 6:1 gears 2"x1.5" prop Didel 4mmx8mm 10 ohm motor.
This is more current than I expected.

Ben
Nice gearbox and nice weight as well.


Billy
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Old Nov 22, 2004, 01:15 PM
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I think the term should be axle despite didel's website. You do just need to glue on the retainers accurately, if the retainer is a bit of insulation you can do without the glue and just slide it to fit. I actually adjusted the motor position in the tube for mine.

Graham
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Old Nov 22, 2004, 01:33 PM
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I found 4 ounces of assorted watch parts for $5.95 at slarose.com
http://www.slarose.com/store2/store....tid=258&step=4
The link Ben posted may be a better deal.
These orings
http://www.slarose.com/store2/store....tid=258&step=4
might make good wheels if you make spoked wheels.

Graham
Thanks
Axis sounds more fitting with the watch gears. The terms used in watch parts is enough to drive you mad let alone sorting through them.
Billy
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Old Nov 22, 2004, 03:10 PM
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I forgot about the retainer when I made my motor, so I had to position the endcap to create minimal play (took several tries). Graham's way would have saved me a lot of trouble.

Istarted looking through more pages on slarose, some of those "military surplus material" in the last few pages of the swiss and american watch parts seem nice-
12 elgin 8/0 4th wheels (the bigest ones)
http://www.slarose.com/store2/store....tid=264&step=4
18 elgin 8/0 3rd wheels (the second largest)
http://www.slarose.com/store2/store....tid=264&step=4
18 elgin 8/0 pinions
http://www.slarose.com/store2/store....tid=258&step=4

I think these are all the same mod? would be great if that's what the 8/0 means, no more sorting watch parts!

Ben
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Old Nov 22, 2004, 03:21 PM
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Ben
Thanks for sifting through the parts. We ought to make a new prhase "going mad" that is a catch all for dealing with small parts, watch or other. Maybe 8/0 means .125mod That seems to be what the largest watch gear I have seen is. Your gears are smaller than .125mod. It appears Grahams gearbox is .125 mod. Ralph's watch gear gearbox is .125 mod. The pinions you have to put in hypo tubes seem smaller than .125mod but may mesh with the .125mod spurs. There are some 10t pinions that seem larger than .125mod. They are a very loose fit on a 4mm pager shaft(axle, axis, rod, tube, etc... ), The .125mod 10t pinions will not fit on a 4mm pager shaft without some reaming.

Billy
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Old Nov 22, 2004, 04:11 PM
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Billy,
I just measured, my gears seem to be ~0.80mod if I measured right (4.7mm diameter including teeth, 60 teeth). I just put a 1.5" prop on my gb, the weight is up to ~0.295g, it feels like it's blowing usable wind.

I agree with the phrase "going mad". I've lost at least half my watch parts to the floor, I pick up as many as I can with a magnet and leave the rest alone.(until I vacuum anyway)

Ben

EDIT:: Billy, just saw the pics of your gearbox, nice! Better craftsmanship than mine, and better photos.
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Old Nov 22, 2004, 06:42 PM
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Another advantage of the watch gears that has not been mentioned is reduced drag. The spur gear while very compact (66 teeth in a 10 mm diameter) is also very thin. I just measured one at 0.008" thick. The interface contact area of the gears is very small resulting in very little mechanical drag if you use ball bearings and build an accurate assembly. I always use ball bearings even though they weigh a bit more than plain bushings. I definately feel that the reduction in mechanical drag is worth the extra weight of the bearings. Drag is something to think about at these very low power levels and is much more difficult to overcome in watch drives than larger drive systems.


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Old Nov 22, 2004, 09:11 PM
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Ben
I doubt my craftmanship is as fine as yours. I don't see how you got those small gears to mesh. Your photos are fine can you get any closer up? I just have a cheap webcam to take photos with. It doesnt take good photos at all from far away but close up stuff is ok as long as there's plenty of photons bouncing into it.

Ralph
Didnt Gordon say something about the watch gear drives you made performed a bit better than gearboxes made with wider gears? I figured he would chime in about that but he's gone on vacation.

Billy
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