i think, that i may of come up with a solution to the whole g25 noise problem. . . i'm not sure yet but i'll be doing some more research on this first before i go ahead and start doing things. . . i'll try to explain my idea a little.. . .

ok we all know the motor has a small metal gear and the wheel has a large plastic cog with a pre-loader which is w@nk. . this is what i'm thinking about converting it to. . . BELT driven!!

it would be possible to re-mount the motors on the same plate but further apart away from the wheel gear, put them on a slider on one of the bolt holes to make the motor more adjustable as at the moment they are fixed, then remove the standard cog and fit one of these. . . .

copy and paste this link into your web browser
http://i.ebayimg.com/t/MXL-TIMING-BELT-PULLEYS-0-08-PITCH-SIZE-15-10-PCS-/12/!BsGId5gEGk~$(KGrHqEH-CEEvQT2HuSGBL2e+0JF4!~~_35.JPG

press on this link
http://www.deepskyparts.com/wp-conte.../08/BELTS6.jpg

correct size and tooth amount hasn't been worked out yet, the tooth amount wont matter too much its the size and the pitch of the teeth that will, then find or make a larger cog for the wheel gear with the same 2mm pitch tooth, chop up the original plastic cog and fix the new larger plastic or even metal cog to the wheel, secure the large cog, mount the motors and the belt, adjust the tension using the motors on the slider and hey presto, one belt driving logitech g25?

idea copyrighted and protected

so tell me what you think?

How is the idea protected?

was a joke, now back on subject please. . .

anyone here have any knowledge of belts and pulleys, where to order?

http://www.fingertechrobotics.com/how-to_pulley_belt.php

Ondrive is a good place to start. And there are various calculators for working out centre distances, belt lengths and pulley diameters.

Quote from tristancliffe :

Ondrive is a good place to start. And there are various calculators for working out centre distances, belt lengths and pulley diameters.

excellent, thanks!

ok one of these belts
dont know which one yet as i need to take my wheel apart.
http://www.ondrives.com/pulley ... tch-6mm-wide-t-belts.html

two of these pulleys for the motors
still unsure of which exactly as need to measure the diameter of standard motor pinion
http://www.ondrives.com/pulley ... ulley-6mm-wide-belts.html

just need to find or ask for a pulley that will be the same diameter as this stock g25 larger wheel pulley, with an offset because the pulley can not be bolted directly to the wheel because it would stick out and wouldn't be in-line with the motors. still hunting. . .

something like this for a quick image

Usual problem with replacing gears with belt is getting the ratio's low enough, you may find you need a huge output pulley to get a low enough ration with the smallest available pinion. 2.5x6 is a little small, it should handle the motor torque ok but you could have double that torque with inertia, belts are cheap though (put a second one on the shaft before assembly so if it does strip you wont have to take the whole thing apart to fit a new one). Good luck with it, should be a big improvement.

EDIT: 2 belts would be better, the single belt could jump out of engagement fairly easily.

with the correct tension the belt "shouldn't" jump?

trial and error?

other wheels have a belt and they don't jump out of sync.

the site ondrive also sells tensioners, maybe something to look into if they do slip, i don't think any teeth would strip as the current gears are metal to plastic, the belts are made out of a tougher material than that plastic gear on the wheel and they don't strip.

it looks to me that a belt can be sourced, cheap and they are readily available and the smaller motor pinion is easy to get hold of, the thing i'm having trouble with is the wheel gear as it has to be mounted 'offset' as it cant be bolted directly to the face as it would stick out past the motor and wouldn't be 'inline' the belt would just fall off when turning the wheel around.

even cars, (twin cam + quad cam), they have belts put under more strain and pressure and go for a couple of hundred thousand miles and they don't jump (with wear and tear they do but it takes years) much more heat is produced in a car engine also.

Jumping could be a problem due to the angle the belt is driven at, cam belts cover at least 90 degrees of the pulley so the teeth are effectively pulled hard together, you have about 45 degrees of contact each side so belt tension would need to be doubled to get the same kind engagement. Doubt it would be a problem but if there is an easy way around it then its a potential problem avoided.

What way is your offset? Could a drilled aluminium or acetal plate line things up or is it the opposite direction where you would need a dish shaped mounting for alignment? Would suggest acetal or even plywood for that, both are strong enough for what your doing and a lot easier to hand work than aluminium. If you need an odd shaped mounting made I could turn one out and put it in the post, I have 80mm dia acetal and its really fast stuff to machine, would probably work out about 10-20 euro +post depending on complexity.

Quote from stan.distortion :

Jumping could be a problem due to the angle the belt is driven at, cam belts cover at least 90 degrees of the pulley so the teeth are effectively pulled hard together, you have about 45 degrees of contact each side so belt tension would need to be doubled to get the same kind engagement. Doubt it would be a problem but if there is an easy way around it then its a potential problem avoided.

i was also thinking this but with moving the motors further away and having a longer belt would aid into having more surface area around the motors pinion but a longer belt would give more stretch and may give some wobble/vibration/unreliability

What way is your offset? Could a drilled aluminium or acetal plate line things up or is it the opposite direction where you would need a dish shaped mounting for alignment? Would suggest acetal or even plywood for that, both are strong enough for what your doing and a lot easier to hand work than aluminium. If you need an odd shaped mounting made I could turn one out and put it in the post, I have 80mm dia acetal and its really fast stuff to machine, would probably work out about 10-20 euro +post depending on complexity.

i haven't taken the wheel apart yet to measure to see what kind of offset would be needed, going to take it apart now, be back soon with some pictures. and thanks for the offer, the problem i still have is getting a larger geared cog with the correct toothed pitch for the belt, they do a large pulley but then the size of the pitch is increased to 5mm from 2.5mm giving larger teeth which would be no good at all for a smaller sized pinion being 5 toothed and around 7mm diameter. i will measure the diameter of the pulleys/gears inside the g25 and see what the closest is can find to match it with the correct pitch pulleys and belt.

ok i've measured and looked and looked again and taken pictures and thought and thought and thought and started to hurt my head! BUT!! this can be done!!

i need to source a pulley that's got over 100 teeth and has 2.5mm pitch and is 9mm width, the diameter of this pulley can be no greater than 96mm as there wont be enough room inside the g25 casing.

i can see they do timing bars and may need to order one just to have 9mm shaved off the end and then drill and tap securing holes and mount it to the wheel in place of the plastic gears/pre-loader. the pre-loader and gear will have to be cut off! the price for this though is like $200 but that's not going to happen, custom items can be made to order so i'll be emailing some companies.
shouldn't be that hard to make one up surely?
http://www.nuovatrasmissione.com/dataload/home/y27qqi.jpg

regarding the offset, the large geared cog would need to have a recess of around 3mm to sit in-line with the motor/pinion. so nothing really needs to be made in regards to lining up the belt, not sure if you can make a larger toothed cog with 96mm diameter, 9mm width and 2.5mm pitch teeth stan.distortion?

the motor pinion(s) need to be 2.5mm pitch and 7mm outside diameter with a 3mm inside bore diameter which can be drilled and then glued tight onto the motor shafts, the shaft diameter is 3mm. these need to be flanged and need to be able to handle a 6mm belt (10mm belts are available but space is tight!) these pinions are easily to acquire.

the belt needs to be 6mm wide and have a 2.5mm pitch, the length to this point is unknown as i need to remount the motors with the pinions on and with the gear attached to the wheel and then measure it, i could do a mock up but it wouldn't be accurate although. i will make either one or both of the motors adjustable or fixed if i can use a spring loaded tensioner one on either side would be ideal but then i am limited on to how much tension i can put up the belt if it begins to slip or jump teeth.

thoughts??

i'm going to head for more on the side of the 10mm belt width! seems do-able as the motor shaft length is over 10mm already so the pulley should fit!

Quote from daveb948576 :

...the pre-loader and gear will have to be cut off!

Do you mean the gear will have to be cut off the main shaft in the g25, its not bolted/screwed on?

Quote :

the price for this though is like $200 but that's not going to happen, custom items can be made to order so i'll be emailing some companies.

Seen that on ebay from time to time, engineering plastics are plenty strong enough and are cheaper than aluminium.

Quote :

not sure if you can make a larger toothed cog with 96mm diameter, 9mm width and 2.5mm pitch teeth stan.distortion?

I can but the teeth take up a lot of time, could do one for a hell of a lot less than $200 though. May be worth checking companies selling that kind of thing near you, even ones with silly prices, as they can often do a reasonable quote for that kind of thing with CNC machines tooled for the job.

Quote :

....glued tight onto the motor shafts, the shaft diameter is 3mm.

Hopefully the pinions you get will have a grub screw for tightening, the pinions on the motors are probably pressed on and can be tricky to remove, worth getting a drift if you don't have one.

Quote :

....length to this point is unknown as i need to remount the motors with the pinions on and with the gear attached to the wheel and then measure it, i could do a mock up but it wouldn't be accurate although.

Once you have the motor mountings decided its easy enough to figure out the belt length, the site you linked to probably has a calculator for it. Count teeth to get the ratio's and figure out how many you need on the main pulley to match your pinion options, 100 teeth at 2.5mm pitch is less than 80mm, get it as big as you can to suit a pinion to reduce strain on the belt and keep noise down. Think there are g25 internal photo's in some forum threads, will have a look later.

its the only thing stopping me that pulley, the amount of teeth is going to bo over 100 but haven't figured it out yet.

pics coming shortly...

pics are being uploaded, let me know if the link don't work.

http://my.imageshack.us/v_images.php

also if you can see in this picture i want to move the motors up and out of the way, allowing more surface around the pinions for the belt and to get the cogs away from each other, i can only move them up there because any further below has no space for the larger motors on the back as the rack is in the way,

the red circled area would need to be cut off and have 6 or so holes drilled and then have the new larger cog fixed for the belt to go around.

there would not be enough room on the shafts for the pinion to also hold a grub screw, two flanges and the surface area with a 10mm belt width. making a nice tight push fit and stuck with alraldite should do the job.

I just found something out!

The motors rotation will be backwards!

If the stock setup has a motor that turns clockwise to turn the wheel to the left then if I fit a belt then all the gears rotate in the same direction including the wheel. Ups! I'm hoping that just by changing the polarity of the motor will be enough to send it the other way or the right way so to speak!

Just a thought the optical sensor will have the opposite readings, what to do??

Link works but wants me to log in, can you change permissions? Motors only need the connections reversing, sensor is fine

[img=http://img11.imageshack.us/img11/1812/g25beltrouteedit.th.jpg]
[img=http://img841.imageshack.us/img841/498/img20120412152511.th.jpg]
[img=http://img560.imageshack.us/img560/6375/img20120412152545.th.jpg]
[img=http://img832.imageshack.us/img832/2797/img20120412154452.th.jpg]
[img=http://img26.imageshack.us/img26/4990/img20120412154246.th.jpg]
[img=http://img26.imageshack.us/img26/624/img20120412153218.th.jpg]

I make that about 16/1, smallest 2.5mm pitch pinion listed if 10 teeth so would need 160 teeth on the main pulley to match which equals 128mm dia :/ If a pully was made 92mm dia (to leave clearance for belt) it would have 115 teeth so 11.5 to 1 ratio, that's a big difference, response would be a lot faster but force would be reduced by about 30% and it wouldn't be good for the motors and amplification circuitry. If you can source 8 tooth pinions the ratio could be got fairly close, about 14.5 to 1. Been searching for alternatives, there are 1 and 2mm pitch options but cant see anything that would go straight onto the motor shafts, will dig into it a bit more later.

fantastic!! thanks very much for your input with the maths which i'm no good at, the 'hole' that's there is 99mm. the belt protruding from the pulley is 0.6mm so the pulley can be 98mm at a push. but 97mm would be ideal, can you work out what the ratio would be with a 97mm pulley please.

although i'm a little puzzled which doesn't take much assuming the pinion and larger wheel pulley is the same size in diameter as the standard then i can't see it making that much difference with overall gearing regards to acceleration/power/speed?

i've also wondered if it worth looking at the sprockets and chains? (EDIT no the pitch is 6mm)

I've been checking through a few other options, chains wont go small enough for the motor pinion's. Multi row v belts might do it, they would need to be quite wide because of the small pinions and I'm not sure what's available. 97mm dia x 3.142 (pi) = 304.774mm circumference / 2.5mm pitch = 121.9096 teeth (near as damnit to 122) / 10 (number of teeth on motor pinion) = 12.2 to 1 ratio. Still a long way from 16 to 1, I really doubt it would do any harm trying that but there is a risk of damaging the motors or driver circuits. The risk would be small though as everything will be designed to work with the motors stalled, doesn't mater what ratio it is if they're not turning.

EDIT: Maybe PM with this if no one else interested, save filling up the forum with posts full of numbers