So after today drills are not working. WTF do we have as alternatives as I see none.

Steve
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Steven Martin
Twisted Constructions
http://www.botbitz.com

Hmm, The single stage spur gear drives I use (and several UK roboteers) , based on the Graupner speed 900 are about as bombproof as Cheyenne Mountain.

Firestarter (Dutch feather) uses astroflights, to create a drive that can outpush a heavy.

A well designed 2 stage gearbox can transform any motor with a suitable rpm into a feather drive.
The batterydrill gearboxes are just the most compact and easely available ones.

First up, everyone who blew up drill motors this weekend, and tell us what has happened. Did the brushes blow? Did the windings short/burn out? Did the gearbox explode?

For the brushes exploding problem, I reckon people start looking into transplanting the armatures from 12V / 18V RS550 motors into RC car motors which have replaceable spring loaded brushes, ball bearing cans / end caps.

For the windings that shorted or burnt out, stop over volting the drills damn it!

For the exploded gearboxes, I think it's a 'potential' issue that the gearbox casings are distorting and loading the gearboxes up too much momentarily, which either jams or breaks the internals. Possibly solve with a fancy housing like the old "AndrewMODs" or a replacement billet housing like Don recently made.

EDIT: Mario, Speed900's don't exist over here these days and when they did, they were >$100. Not really an easy option for people to source reliably.
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Speedo 900's over here are rare too, that is a fact.

That is why we're using non-overvolted Gimson GR02's in our new feather. Those are just batterydrills in an easy package.

And, as I wrote, a well designed 2 stage gearbox will do the job as well. Problem will be the weight and size compared to the drill epicyclics.

And overvolting the drills will also affect the gearboxes, not only the motors. Actualy, chances are that an overvolted drill motor dies faster due mechanical issues in the gearbox than due the overheating effects of the overvolting itself.

Should probably have put forward a few specs as well. Drills are used so frequently primarily as they are relatively cheap and they are easy to get.

I think for anything to be a viable option it needs to weigh < 1kg and be < $70.

The obvious option is banebots but they are too expensive for something which is essentially just a drill in a nicer package.

Glen has shown me some photos of a motor from an impact wrench from supercheap and I also found a compressor which is direct drive both for $50 which could be potential candidates.

Steve
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Steven Martin
Twisted Constructions
http://www.botbitz.com

None of my robots have needed anything more than the andrew-modded drills yet, but here's what i was thinking.

Buy a pair of the $50 impact wrenches for the motors which are 800-900 size but low rpm plus they seem to have real brushes. (pic is of an rs750 so its a chunky motor) then build a one stage chain drive gearbox for it using two lasercut steel plates and flanged bearings (cheap).

Safe, low rpm, huge motor, could be worth a try. Certainly so if the motor can be obtained without the extra impact wrench bits.




The p90 banebots work perfect as far as gearboxes go but pretty pricey, and the motor issue remains which is the biggest problem especially with people slamming them foward and backwards while driving
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For me it was exploding gearboxes. TBF 3 of the 4 I killed had plastic gears, but one did not, and in 2 cases there was also a sheared gear pin.

A billet gearbox housing with decent drill internals might be worth doing. It would be good if we could come up with a good design, prototype it, test it, agree that we like it and then organise a group buy or something and do a CNC run of a big bunch of them... that's the dream

ALSO

I do happen to have access to nearly 100 Ozito 12v drills (the newer style gearboxes with the pin mount holes) BNIB minus batteries and chargers... for a good price. I mentioned this to a few of you today - Which will be the subject of a different thread I shall post up soon
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<Patrician|Away> what does your robot do, sam
<bovril> it collects data about the surrounding environment, then discards it and drives into walls

quote:

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Originally posted by maddox:
That is why we're using non-overvolted Gimson GR02's in our new feather. Those are just batterydrills in an easy package.

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The Banebots P60 has been awesome in Scissorhands; I have bent some output shafts and bearings, but all damage has been cheap & easy to repair. Zero gear or carrier pin breaks and only $54.50 USD + shipping for the 2 stage version.

Good motors are harder to come by. I use 75 turn RC motors and they still have brush burn-out problems at 22V, plus they are surprisingly shock sensitive. I want to try out brushless motors but they may be just as delicate.

Biggest problem with brushless motors is starting torque. You can get away with it but I think for really good control it has to be sensored. Could see what I could do maybe but too many other things to do.

Steve
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Steven Martin
Twisted Constructions
http://www.botbitz.com

Another gearbox setup that might be of consideration is the VersaPlanetary from VexPro - http://www.vexrobotics.com/vexpro/gearboxes/versaplanetary.html

They can accept a bunch of motors and have a hex shaft which is a bit nicer then keyways or threaded shafts. There is a retarded process for ordering them (due to the way they are all modular and expandable) but IIRC, Charles Guan has a guide/info on how to order them correctly.
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don't even start on drill gearboxes >_>

for me it just sheered teeth, both the gears and the single gear on the planet carrier which then caused the motor to lock up and in turn burnt out the motor.
Setup was in no way out there or crazy. 5s lipo with the 18v drills running bunnings red wheels.

the gears only ever broke on the second stage which i believe in the kmart drills well in my ones which were so inconsistent in regard to gears used in them (out of 4 drills 2 were all metal 1 was all plastic and 1 was half and half >_>) they were a thicker gear to the ones used in the first stage

Never had problems with drills for drives before whether it be in a wedge or spinner, even getting hit by another spinner the impact wasn't enough to shatter the gearboxes.

so all i can think of is that the quality of these kmart drills are absolute rubbish.

when i get a chance going to see if its possible to laser some gears at work that might be somewhat stronger then these lame cast chinese crap thats in these kmart drills.
thats my possible solution anyway.. i mean when do you ever destroy the housing of the gearboxes. its either the motor burning out or the gears shattering which are usually related to one another so possibility of a laser order of several hundred replacement gears might be an idea
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quote:

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Originally posted by Jaemus:

quote:

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Originally posted by maddox:
That is why we're using non-overvolted Gimson GR02's in our new feather. Those are just batterydrills in an easy package.

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Do you have a link to a source of these at all?

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If the GR02's could be landed in Aus at a half decent postage rate should get under Steve's minimum requirements.
Looking at international orders page, it is reasonable costings and you can save the VAT. http://www.gimsonrobotics.co.uk/international_shipping.html

if they live up to their website, could be a good, near drop in solution for current drill users and the shaft looks easy enough to use for new designs.

Kmart drills from reports here do not seam to be living up to the standards of the old DSE. I killed many a motor with my andrewmods or virgin gearboxes but not once have I killed a gearbox and vic fora time had a few long pushing events mainly attended by twackbots and wedges.
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Remember to trust me, I am an Engineer.

http://www.youtube.com/watch?v=rp8hvyjZWHs

After currency conversion and shipping, the Grimson gearbox is more expensive to import than the Banebots gearbox. With the Banebots, you get more ratio choices, four gears per stage (more load capability), larger carrier pins, more output shaft options, stronger 2024 aluminium, and they may be lighter as well. You can also get the P60 with a mounting plate for 775 motors.

At today's exchange rate a pair of Grimsons will cost at least $157 to import, while a pair of P60 gearboxes will be about $143. That doesn't include the crappy currency conversion from most banks or the VAT refund.

EDIT: the cost to import two P60 gearboxes with 775 motors is about $225 AUD, or save money by getting the motors locally. Your other option with this gearbox is an outrunner with a 5mm shaft - a very interesting option IMHO!

Last edited by Nick on Mon Aug 05, 2013 7:54 am; edited 1 time in total