ive been watching this and the wheel is looking awesome.. any news on the new cogs and how its coming along?

James

Quote from jameso77 :

ive been watching this and the wheel is looking awesome.. any news on the new cogs and how its coming along?

James

Hey, i got the new cogs, but i still havnt found any time to make the new blocks... i only have 3 days in the week time for it, and i have to do alot there aswell... I'm actualy considering to stop this little project, because i think it will cost too much money and effort to make it work. I doubt if the FFB is proper after the last step I need to do.

''It will coast too much money.'' How much does it is?

Quote from PioneerLv :

''It will coast too much money.'' How much does it is?

Hi, thanks for the interest. I just ordered New stuff from a mate of an other forum. It will arive tuesday (or later). The costs are something like 180 euro for the ballscrew. and 15 euro for the new parts. The other parts are home made, so no costs. New cogwheels are 20 euro. I also rebuilt the wheel, of a new material. pics soon. so the costs are 215 euro or something like that.

215 euro is quite expensive

id rather buy a G25 for the same amount of money and then you get a clutch pedal and shifter, AND is saves alot of work

but still its a nice project

Quote from G!NhO :

215 euro is quite expensive

id rather buy a G25 for the same amount of money and then you get a clutch pedal and shifter, AND is saves alot of work

but still its a nice project

Yeah, more people would agree on that. I agree it looked better on paper. But maybe this will work, and it could be alot of fun. Fingers crossed. If not, i'm going to throw it through my window.

Quote from Bose321 :

Yeah, more people would agree on that. I agree it looked better on paper. But maybe this will work, and it could be alot of fun. Fingers crossed. If not, i'm going to throw it through my window.

lol, and how about the motors? you already know which ones to take, or do you already have em?

Quote from G!NhO :

lol, and how about the motors? you already know which ones to take, or do you already have em?

Ordered original (almost new) MOMO ones. I don't think the current controler can handle a new motor.

It is so nice to see people who like to do something with his hands. Sure, it needs to invest some money, but you made it and you trust it.

Waiting for news and good luck!

Great to see your giving it a go! I followed it from the first page and i'm quite eager to see how it turns out.

Theres a lot of things you'll learn from this that will surpass any costs you might spend, for example you know you built it yourself.

Its quite easy to go out and buy it all done, but to know how it was built and that it was built by yourself is a great achievement

Don't be discouraged, money comes and goes but new life experiences and knowledge will stay with ya for life!

I say Go for it! Not long to go

btw when its finished i'd like to see it in action

Quote from PioneerLv :

It is so nice to see people who like to do something with his hands. Sure, it needs to invest some money, but you made it and you trust it.

Waiting for news and good luck!

Thanks. hope it turns out good!

Quote from polepositiondriver :

Great to see your giving it a go! I followed it from the first page and i'm quite eager to see how it turns out.

Theres a lot of things you'll learn from this that will surpass any costs you might spend, for example you know you built it yourself.

Its quite easy to go out and buy it all done, but to know how it was built and that it was built by yourself is a great achievement

Don't be discouraged, money comes and goes but new life experiences and knowledge will stay with ya for life!

I say Go for it! Not long to go

I totaly agree on you. I will come with news soon

Quote from G!NhO :

btw when its finished i'd like to see it in action

Ill find a way to film it.

Quote from Bose321 :

Sorry for the triple post, but does somewhere here, or do you know someone that knows a bit about FFB systems?

im thinking of buying a controller and a AC Servo. but i heard it is VERY difficult, and the AC servos are very expensive. Does anyone have some info to share or links, whatever helps me.

Regards,

-Bose

Hi Bose, I can tell you a bit about the MOMO Racing FFB transmission which might make your lack of power at the wheel clearer. MOMO Racing uses a 39:1 overall gear reduction. The motor produces approximatly 42 mNm of torque. If you multiply 39 times 42 you get 1638 mNm at the SHAFT. But, at the wheel rim you only get about 12.8 (wheel dia is about 256 mm). Your set up appears to use the first reduction gear from MOMO Racing attaching it directly to the screw shaft to which the wheel is attached. The motor pinion has 20 teeth, the first reduction gear has 120 teeth yielding a 6:1 reduction. This means that at your SHAFT you are getting only 6X42 mNm=252, and therefore at the wheel rim you are seeing less than 2 mNm. You can see why a double reduction gear set is required: the second reduction pinion on the double gear has 20 teeth, the main gear has 130 teeth yielding a 6.5:1 reduction, if you multiply 6.5X6=39. It is this power of mutiplucation that produces the torque that is needed from a cost effective motor/power supply.

Another aspect of FFB response is inertia in the system. Everything that has mass has inertia. Interia is what makes someting that is not moving hard to get moving, and something that is moving hard to stop. Increased inertia in the FFB system absorbs the force producing an overall smaller "feel" at the wheel. By adding large metal parts the inertia of the system increases decreasing the available force. Another serious aspect of this added inertia is tooth strength. The teeth in MOMO Force's transmission are desgned to accept a given bending stress without failing. The highest stress happens at the mechanical "stops". Inertia makes the system (wheel, shaft, gears, motor rotor) want to keep rotating. The stop makes the whole thing come to a very quick stop. Force equals Mass X Acceleration (F=Ma). In this case very large forces are created because the (de) acceleration is very high. And, due to the nature of FFB gear drives, the same teeth see this force over and over again until that fail due to fatigue of the plastic. Your system has alot more rotating mass which will destroy the plastic teeth of the original MOMO Racing first reduction gear.

Another aspect of FFB transmission design/function is refered to as "frequency response". This is the ability of the transmission to reproduce the frequency (back and forth forces) at the wheel rim. Gear based transmission have small gaps between the teeth of the gears called backlash. This backlash limits the highest frequency that can be felt at the wheel. Think of it this way: the motor turns back and forth at a given frequency. As it does it must "take up" the space between the teeth before any force can be transfered to the next gear tooth. IF it is changing direction so quickly that it is turning around BEFORE the gap is removed, then no force is transfered to the next tooth and the maximum frequency response has be reached. Control of the system backlash is of very high importance in FFB transmission design.

As you stated, these dc motors have a "shocky" feel unpowered. This is called "cogging" force and is a function of the motor's design. Logitech FFB motors are custom designed to minimize the cogging effect as much as possible. But, cogging and motor torque are directly related: less cogging means less torque. A higher transmission reduction ratio minimizes the cogging feel: there is less feel at the wheel's rim as small wheel rotation angles result in large motor rotation involving many cogging steps. BTW: G25 uses a 16:1 reduction which caused the need for very special, very low cogging, custom motors to minimize the cogging feel at the wheel.

Finally, I have question about your design: what purpose does the "screw shaft" and associated "square mass" serve? It appears that the original MOMO Racing wheel is attached directly to the shaft. If so, then the screw and added system mass do nothing for you that a straight shaft would do, while adding cost and interia to the system.

Hope this helps. As you can see, a great deal of thought and engineering go into making FFB wheels that work well and are affordable.

Good luck with your project!

Thanks for the post. The ballscrew is there to stop the unlimited movement of the wheel. You seem like a smart person, what should i do to improve it? What do you mean by 'square mass' ?

Quote from Bose321 :

what should i do to improve it? What do you mean by 'square mass' ?

Just throw more money at it and the problem should go away

Quote from CSU1 :

Just throw more money at it and the problem should go away

Throw money in what parts?

Quote from Bose321 :

Thanks for the post. The ballscrew is there to stop the unlimited movement of the wheel. You seem like a smart person, what should i do to improve it? What do you mean by 'square mass' ?

Hi Bose, I think I understand now: the "square mass" I refered to is your "moving stop". It moves up and down the ballscrew and stops at the ends. Is this correct?

If so, as I mentioned, your "stop" must be accelerated and deaccelerated at what ever frequency that the FFB system is sending the wheel. This "absorbs" some of the forces and degrades your experience.

As far as what you can do. If you use the same motor I would increase the gear reduction to near stock or higher using stronger gears or perhaps a belt drive. If you use a belt drive tension on the belts will be critical to the feel and losses in the system. Please note that the electronics are design with power constraints based on the stock motor/power supply and can be burned out with a higher amperrage motor. There is also "over current/back EMF" protection on the board which can affect your driving experience if the configuration is not correct.

Next, I would make the "stop" weigh less (lower the mass).

I need to find out a few things about the optical encoder on MOMO Racing which will help you determine what range you can obtain, as MOMO Racing, as you know, is a less than one full turn device (240 deg's I think) as so it does not need to calculate what turn it is on. This is very different from DFP/DFGT/G25 which are multi turn devices which BTW would be more straight forward for you to modify.

Please tell me if my assumptions about the "stop" are correct and let me think about this and get back to you later.

Quote from mcman :

Hi Bose, I think I understand now: the "square mass" I refered to is your "moving stop". It moves up and down the ballscrew and stops at the ends. Is this correct?

If so, as I mentioned, your "stop" must be accelerated and deaccelerated at what ever frequency that the FFB system is sending the wheel. This "absorbs" some of the forces and degrades your experience.

As far as what you can do. If you use the same motor I would increase the gear reduction to near stock or higher using stronger gears or perhaps a belt drive. If you use a belt drive tension on the belts will be critical to the feel and losses in the system. Please note that the electronics are design with power constraints based on the stock motor/power supply and can be burned out with a higher amperrage motor. There is also "over current/back EMF" protection on the board which can affect your driving experience if the configuration is not correct.

Next, I would make the "stop" weigh less (lower the mass).

I need to find out a few things about the optical encoder on MOMO Racing which will help you determine what range you can obtain, as MOMO Racing, as you know, is a less than one full turn device (240 deg's I think) as so it does not need to calculate what turn it is on. This is very different from DFP/DFGT/G25 which are multi turn devices which BTW would be more straight forward for you to modify.

Please tell me if my assumptions about the "stop" are correct and let me think about this and get back to you later.

Yes, you are right about the stop. Why should the stop weigh less? would it improve the FFB? Maybe you have something like MSN so we could chat easier.

Quote from Bose321 :

Yes, you are right about the stop. Why should the stop weigh less? would it improve the FFB? Maybe you have something like MSN so we could chat easier.

Hi Bose, at various frequencys, say, running over a bump strip, the quicky changing forces applied to the system will be better with a lighter stop.

Anyway, I don't use MSN so just let me get some more information and get back to you tomorrow.

Quote from mcman :

Hi Bose, at various frequencys, say, running over a bump strip, the quicky changing forces applied to the system will be better with a lighter stop.

Anyway, I don't use MSN so just let me get some more information and get back to you tomorrow.

Alright. Thanks for the help already!

Quote from Bose321 :

Alright. Thanks for the help already!

Hi Bose, I have done a little looking into MOMO Racing and have some insights for you to consider as you go forward with your project:

First, MOMO Racing uses a "geared down" optical encoding system (same unit is used in Driving Force Pro). Basically, the system uses thin slots in a rotating disk to create "counts" and to determine direction. These "counts" provide the firmward with the information it needs to know where it is between the mechanical stops. In the case of MOMO Racing, the wheel rotates less than one full revolution, so, upon startup, the wheel rotates one way until it hits a mechanical stop. The firmware resets the counter to zero, then rotates the wheel the other direction until it hits the other stop. It then divides this number (full range) by two and rotates the other direction until it reaches this new number which centers the wheel. After this calibration, when the wheel is turned the firmware keeps track of these numbers and always knows where center is. Now, the processor that stores these numbers is designed to keep numbers of only a maximum expected size. If the encoding system feeds more counts above this number then it looses counts/stops working. I do not know what this number is, but I am fairly sure that if you feed 900 degrees worth of counts to the device it will not keep track.

So, this is what this means to your project: For it to function you will need to further gear down the optical encoder to create roughly the same number of counts over the larger wheel rotation angle. MOMO Racing is a 240 degree rotational device, so to make it a 900 degree device you would need to reduce the rotation of the optical encoder disk by 3.75 times. NOTE: this greatly reduces the accuracy of the steering wheel as a one degree rotation of the stock wheel produces about 10 counts, divide that by 3.75 yields only 2.8 counts. To accomplish this gear down would require a new optical encoder frame with a double gear between the stock 14 tooth pinion and the optical disk's 35 tooth pinion. You will have to calculate the ratio based on the two gears you assemble to make this double gear.

As you can see, this is not an easy or a good way to make a 900 degree wheel out of a 240 degree wheel. So, I have a few suggustions:

First, you could make the changes to the FFB gearing I reconmmended (39:1) then, move your stops in until they produce 240 degrees. Once the system is working you could then move the stops out a little at a time to see where the "saturation" point of the processor is. This would probabily be less than one full rotation.

Or, your cound leave your current FFB gearing, which is 6:1, yielding a per degree of wheel rotation counts of 1.6, then move your stops to provide the total expected counts which would be a 1560 degrees of rotation! But, you would have no/very weak FFB.

Or, you could change the FFB gearing to yield a total number of counts equal to a 900 degree device which is a ratio of 10.4:1. This would give you some level of FFB while allowing the device to boot up. Your accracy would be less, but might still be OK. Note: if you keep your stock MOMO Racing motor pinion (20 teeth) and make a single reduction device the main gear would need to have 208 teeth. Of course, you could reduce the number of teeth on the pinion allowing a smaller main gear to be used.

Or, you could buy a DFP, use all of it's internals stock, and get true 900 degrees as it's processor is looking for a bigger number based on 2.5 turns of the wheel. One issue with this approach is the 200 degree mechanical stop in DFP. The firmware expects to "see" and operate this sliding stop during start up. Fooling the firmware could be tricky.

Or, you could buy a DFGT, use all of it's internals, get true high accuracy FFB without the problems associated with the sliding 200 degree stop as DFGT does not have this stop. But, DFGT uses a direct drive/anti backlash optical encoder (same module as G25) which you would have to deal with. You could attach your ballscrew directly to the FFB transmission main shaft (where the DFGT wheel is currently mounted) to get around this issue. Still, DFGT is a PS3 device, with all of the associated buttons. You would have to rewire the MOMO wheel with the expected wires routing the MOMO paddle shifters to the DFGT paddle shifter buttons and the other six buttons as required for your game play on a PC. This is doable, just keep the DFGT wheel panel off to the side and run wires up to the MOMO wheel.

Finally, you could buy a G25, get smooth/strong FFB, solid construction, and a clutch/shifter. I use a G25 in LFS and GTPrologue mounted on a Playseat that I customized to raise the shifter and move the pedals over to the right and am very happy with it.

Anyway, I will keep watching to see what to decide. Good Luck!

Hi, i already ordered new parts(original momo motor plus all the other internals). I don't know how easy it is to do all the things you said, and what it will cost, but it sounds prety good. I'll have to discuss it with my brother. He is a bit better in all this

Quote from mcman :

Now, the processor that stores these numbers is designed to keep numbers of only a maximum expected size. If the encoding system feeds more counts above this number then it looses counts/stops working. I do not know what this number is, but I am fairly sure that if you feed 900 degrees worth of counts to the device it will not keep track.

I've played with this sensor before. If you rotate past 120 degrees in one direction, the reading stops increasing. But as soon as you unwind it back, the reading starts decreasing as if from 120 degrees. So if you rotate 150 degrees in one direction, the new center will be moved to 30 degrees, and the opposite end will be -90 degrees.

I believe this is more a driver design, though, instead of hard/firmware limit. But gearing down the optical disk should be necessary if you don't touch other things.

Hi all!
Last week the new motor + circuit board arrived. I also addapted the gears to 720 degrees. The Force Feedback is much better now! But still not really massive. And I have the strength maxed out, so. I have no new pics/vids yet. I am considering to add a seconds motor. But I don't know how to attach that yet. And I have no second Adapter, so I don't know if that will work. Next step is to make a cover for it, and to make 'stops' to make it stop from turning more then 720 degrees. And I have to solder the wires to the circuit board again. I'm still testing, and everything looks good. Motor gets quite hot though. I'd like to hear some responses from others.

Regards,

Gerben Bol

Pretty damn impressive build!
But I gotta ask, where have you read about that the G25 is a bad wheel?
Those people must have been retarded or something imo ...
The G25 is GREAT (have one myself) and the best wheel on the market!