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View Full Version : What if... (non-xmod-based AWD Pro-Z)


color01
2006.01.10, 10:22 PM
question is, is it worth giving a go? i'm 60-70% done, just need to finish up the wheel adapters (easy), suspension arms (damn hard) and spec'ing the thread sizes in case i actually have a machinist do this.

it'll serve as a test base for belt drive w/o tensioners, cf plate front suspension, and a special ball diff. this design isn't quite what i have in mind for a final product, rather just a test bed and to use the square TE-37's i still haven't found a use for. (yes, it'll use standard MR-01/02 wheels, all i have to do is change the knuckle design by 2.5mm.)

at least i have the diff balls i need. :rolleyes:

http://img191.imageshack.us/img191/3729/awdminiz0hn.jpg

you can probably figure out where i'm planning to put these belts. and yes, i've done my homework before attempting this piece of graphic crap.

btw, i read/heard draconius has something similar going on. thought his was shaft drive though?

gulfclk
2006.01.11, 12:20 AM
Xemet has done something similar. Here (http://xemet.altervista.org) is his website.

imxlr8ed
2006.01.11, 10:25 AM
Never got to finish mine... maybe one day !!! :rolleyes:

xemet
2006.01.11, 02:46 PM
yeah color01, nice setup.
But I see there are still some problems to solve...
The central pulleys seem to be too small in my opinion, I don't know how much teeth they have (I think 9-10), but consider that the smaller is the pulley and the higher is the resistance of the belt. Also belts are a little more resistant than a shaft transmission so I think that four batteries with 4,8 Volt are not enough, I suggest you to tray a lipo battery, they are small and very light.
Also I don't like very much the rear suspension system, the central pulleys move with the rear plate and the motor (just like in a mini-z with a h-plate) but here is a belt and the belt is twisted while the suspension is working, this cause resistance, also I don't understand what happens when the rear flex so that the distance between the center pulley and the front differential change. Or maybe I've not understood the system, maybe there is no h-plate and you have to design an arms based suspension . But I don't think there is enough space for it.
Also the space for the servo and electronics is not so clear...And the steering system with drive shafts has to be designed.

However, it is a very good base, continue on this way.

color01
2006.01.12, 01:24 AM
thanks xemet,

i saw your work some time ago while i was working on this thing...

"dang, that's cool." (and my devil's voice then says, "but i can do better." :p )

anyhow, like i've said before, i'm building this to test out the capabilities of a belt drive chassis. i'm going to keep the y-plate for simplicity, as i want to keep machining costs low as possible for now.

and the belts, i think they will be ok for a test bed, as a "worse-case scenario" thing; for the final model i will not have to deal with the small pulleys, just the differential pulleys (which i believe are plenty big enough).

i don't think the h-plate twisting will be too detrimental to performance either; the suspension on a micro rs4 allows the belt to move and twist much more than my concept, and yet the mrs4 is said to be a decent performer. i'll see about it.

i will not worry too much with the electronics either; as a test bed, i'll just put the board to the right, the servo to the left, maybe a couple grams of balancing weight, and it should be fine. the tierod will be held in place by a two-piece "sleeve" of sorts, so there will be very little play but hopefully no binding. knuckles will be similar to MA-010.


believe me, i have everything down and precise in my head... i just don't have too much time to actually work on the darn thing, i only have minutes here and there to spare, especially with finals all week long... anyhow, thanks for the comments guys. much appreciated. :)

xemet
2006.01.12, 03:06 AM
no one has much time to do these things...unfortunately...maybe those that work for kyosho or other model brands. We have to to them in our free time.

Of course my car can be made better, and I can say very much better. I know how to do it better, the initial design of the car that you see in my website is the simplest possible due to the limitations I have with my machines (my lathe and my mill). If I own a 100.000 $ mill, the car would be much better... :) The art of designing include the art of understanding what you can do and what you can't do with your workshop.

The only thing I'm pretty sure that will not work is the belt system with an y-plate, I know my belts and I've worked with them. They have tolerances of 1/10 mm...
MicroRs4 is much bigger than a mini-z and pulleys in the microRs4 are much much much bigger...

However, do your tests and let us know. If it works, this setup is very nice, I will buy one if you succed in getting it produced!

What about the diffs? Have you designed your own?

bye

color01
2006.01.12, 12:50 PM
well, i don't have my own workshop, so perhaps i can just run wild with the design? hehe.

i'm certain the belt system is going to have small flaws... but according to the qualitative analysis it should be minimal. if the layshaft were to be at the differential's position, suspension movement would cause it to move away from the front diff, stretching the belt. if the layshaft were at the y-plate's pivot point, suspension movement would cause it to move towards the front diff, making the belt slack. i put the layshaft right about between the differential and the y-plate pivot point, so with a bit of luck the layshaft won't alter the belt tension too much.

that said, the final version (if this thing works) will have only 1 belt, and 4-wheel independent suspension using cf plates as springs. in that situation the suspension movement doesn't even affect the belts, so in the long run i shouldn't really have to worry about the belts.

yes, i've designed the diffs; they use 6 balls, and the diffs are about the same size as the ones on your m24-pro. the only thing i'm not certain about is whether to be traditional and use steel diff plates (which, in my experience, slip more than i like them to), or do something strange and use soft rubber. in theory it allows for 100% power transfer, but by tightening the diff i can adjust the left-right slip by itself. *shrug*

keep the comments coming! :)

xemet
2006.01.12, 02:24 PM
yeah, you can run wild with the design, but, keep in mind, the machinist will go wild with the price if you design too much complex parts ;)

My diffs use steel plates and, yes they slip a bit too much for my taste, but if you tight them you don't notice it very much, specially with the brushless motor.

I was thinking, like you, to mount some different material plates, but I think that they will wear very quickly if the material is not hard enough.

Try to take a look to this huge online shop, maybe you can find something different:

http://www.minibearings.com.au/products_index.html

good bye! Keep on this project!

color01
2006.01.12, 03:23 PM
of course. i'm trying to keep it simple, i swear... ;)

i think i can find some medium-hardness rubber, that will serve a good purpose in the diff... i honestly don't like "traction control" feel provided by slipping plates, so perhaps rubber plates will be a better plate material. plus, i'll be using a regular 130 motor, so if there's slipping going on, i'm going to feel it. i'll look for the rubber stuffs.

and that's a good site... so far i've only known www.sdp-si.com, which is pretty good too. thanks for the link!

xemet
2006.01.13, 03:04 PM
yes, I've purchased my first parts on sdp website, yesterday I've found that new website that is very cool. Althoug sdp seems to have lower prices.

I was thinking...what about mount different material balls with the steel plates? They have nylon balls, teflon, acetal...and a lot of different materials...I think I should try.

They also have a very miniaturized thrust bearing that is very nice for the diffs, but it costs about 6$ each...that is too much for my intentions.

I don't know if rubber plates would work...maybe you can reduce the slip with rubber, but I don't think the differential can work properly in this way...it would work more as a rigid jooint than a differential.

Good bye

color01
2006.01.13, 06:58 PM
well, some material that allows for grip while not wearing itself out too much... perhaps silicone?

if you used a soft diff plate (i.e. rubber/silicone) you might be able to get away with the acetal balls... i could try that along with you. it would be a very lightweight diff, not having any steel in there.

hard silicone won't "envelope" the balls too badly, so it won't be too rigid. i've tried this experiment with electrical tape in a xmod diff -- so long as your diff plate does not squish and stay squished, it will work. if it squishes, there will be noticeable "steps" when your differential plates move.

color01
2006.01.14, 07:51 PM
i can't find the edit button, so forgive me...

i got the front suspension done, the thickness of the arms is a best-guess thing, judged on typical h-plates. i won't worry about that too much, but i'll learn from it when i design the final version. i'm doing the towers right now, just wanted to let you guys see the actual suspension first.

http://img63.imageshack.us/img63/5457/awdminiz28qr.jpg

xemet
2006.01.15, 03:47 AM
ehe, that piece with the ball will cost to you a lot...and it should be made of metal because it seems very breackable.
The knuckle, with this type of uniball joint can't be done in metal but only in plastic. Maybe plastic is better...but, you know, I love aluminium parts...

Maybe you should thy the contrary: ball solid with the knuckle and cap-joint on the suspension arm.

If you want to use CF for those plate-type suspension arms, I think you have to made them less thick than an h-plate, I guess less than 1 mm if you use this D-type design, in order to give a right ammortization to the car. All depends of course by the final weight (I guess about 180-200 g if there are aluminium parts).

I will wait the final suspension design.

Bye

color01
2006.01.15, 12:14 PM
thanks for the suggestion, i'm planning to have the ball piece in aluminum and the knuckle in delrin. that should be ok.

i thought about having the ball on the knuckle, but i decided not to have an all-aluminum knuckle as that would be much heavier than i want. and my final goal for this machine is to have minimal unsprung weight, so that's not going to do. would there be a way i can have a delrin knuckle, but an aluminum ball? then i could screw the ball to the knuckle, and everything would be ideal (and cheaper). except, i fear that the normal ball joints (you just screw them in) might come loose easily.

maybe i should try both ideas? that would be the ultimate guess-and-check thing to do...

and about the suspension arms; i expect this car to be in the low 180g range, as the servo is tiny, the electronics are light, and i'm using as little aluminum as possible. so for the final version, the suspension will be thinner (you'll just have to wait ;) ), but for now, i'm making them thicker so i can guarantee they won't break while i'm testing (and leave me stranded and ticked off).

for mini-z owners... could someone do me a favor? i don't know how far away the holes for the front clip are away from the front axle-line... if i could get a measurement for that, that would be greatly appreciated. i don't need something incredibly precise; but please give higher guesses rather than lower ones, as i can sand down a front clip if i have to, but i can't really extend one very well. thanks!

xemet
2006.01.15, 03:05 PM
the part with the ball, in alluminium, will cost to you a lot...it is a very complex part to machine, you should definitively try to design the part in order to use the ball joints that you can find in the market. I'm talking only of the ball, not the cap. So, you could make the knuckle in delrin and screw in it a brass or alluminium ball and design a plastic cap (nylon or delrin) that will be on the suspension arm (my way). Or if you want to use your design, you should try to divide the alluminium part that have the ball in two parts, so that the ball will be of the standard type that you can buy easily, simply screwed in an alluminium support designed by you.

The distance you need is 8 mm in a mr-01.

Good bye

color01
2006.01.15, 10:58 PM
i'll put the ball on the knuckle... it'll be a frictional fit for now, i suppose with a little threadlock, it will stay securely.

oh, and thanks for the measurement.

xemet
2006.01.16, 04:17 AM
ah, I've forgotten it yesterday: don't think that delrin is so much light than alluminium...

delrin density is 1,41 g/cc while aluminium is 2,7 g/cc...

If you consider the dimension of the parts you will note than maybe, if you're lucky, choosing delrin instead of aluminium you can save 1.5 - 2 g...

You can say, yes, 1 g here, 1 g there and I will save a lot...I think not.
The parts that will determine the weight of the car are others, batteries, chassis, motor, servo, electronics, screws, leads...

So, if you have the complete car that weighs 190 g using alu, the difference if you use delrin will be that the car will weighs 180 -185 g. Don't believe that you can pass from 190 to 140 using delrin. 10 g can be important on a car like this, but, remember, aluminium parts are virtually unbreackable...

good bye

color01
2006.01.16, 08:53 PM
xemet, the figures say delrin is almost twice as light! if they're accurate, a 1g alu part will be 0.53g in delrin... for a couple of 4g parts, no the difference is not going to be large, but every last part that won't suffer significan't abuse should be as light as possible. i do go through the dimensions on every part to try to get stuff as thin as reasonable.

oh well. i did redesign the knuckle, so now there's an alu ball that fits into the knuckle (will probably need adhesive...), and a delrin ball cup up top -- i hope it's a simpler piece now, it seems simpler to my mind.

http://i42.photobucket.com/albums/e345/color0/awd-miniz3.jpg


and for fun, a little detail of the rear pod... thoughts?

http://i42.photobucket.com/albums/e345/color0/awd-miniz4.jpg

xemet
2006.01.17, 03:14 AM
the ball can simply be screwed into the knuckle, all the ball joints you will find on the market are with a thread stud.

This design is better, because I think that delrin parts will be done using a molding process while alu parts probably will be done by machining.
And machining a ball as a part of a piece in alu is not the easiest thing...

There is another problem that I've thinked about...
These pulleys, gears etc, you have choosen it from a catalogue or you would like to machine them? Machine gears and pulleys can be very very expensive, so the better thing is to design parts in order to use commercial products. Or at least modified commercial products. So study the distances, the numeber of grooves that you need and the belts you would need. For example, Gt2 2mm belts pass from 38 teeth to 50 teeth...and this can be a problem for the design.
The rear diff I think will be like the one on the mini-z, with balls on the gear, but with the add of the pulley that should be solid with the gear, right?

good bye.

color01
2006.01.17, 06:22 PM
well, the design here unfortunately limits the size of the ball to about 3.5mm; even so, i have to flatten part of the ball to allow the whole ball assembly to sufficiently clear the wheel. so i'm not sure if there are any commercial, threaded ball joints i can use for this purpose. i'll browse through all the catalogs i have.

the pulleys are all from a catalogue; the mesh is MXL (~2.03mm), and the pulley and belt sizes are spaced very close together, i can pick almost any size i want. i can probably modify by hand the pulleys to fit on the shafts/diffs if need be, but the most important thing is that i can get the pulleys pre-made, which is, like you pointed out, much cheaper than making them.

and yes, you're right about the rear diff, i'm keeping it as close to a mini-z design as possible (but i do have to have the pulley on the side). notice that i did try to reduce the rotational inertia of the unit a bit; it looks like a slot car diff now, with holes, and the balls close to the shaft. i'd like to see how a design like this works.

xemet
2006.01.18, 02:24 AM
The smallest commercial ball studs have a ball diameter of 3,8 mm and a stud thread M2, so I think these should be ok for your design.

Pulley and belts MXL probably have more sizes than GT2, so you're lucky.

Take a look also at the pulley stocks, these are round bars about 100 mm long that have the grooves like a pulley, you buy one and this bar can be machined in order to become a pulley like you want. In a pulley the parts that are hard to be machined are the grooves so if you give to a machinist the pulley stock it will be like he's machining a round bar and the cost will be highly reduced.
Pulley stocks are significatively cheaper than pulleys.

Good bye

color01
2006.01.18, 06:39 PM
can you give me the link to the 3.8mm balls? they will fit if i screw the balls to the top suspension piece (reverting back to my suspension concept). i just might have to move the kingpin offset back a little.

and i didn't know that about the pulley stocks... i can have those cut, then have the endplates cut and i'll bond the pieces together myself. very good idea, thank you very much! :)

xemet
2006.01.19, 03:06 AM
Well, I've purchased these ball joints in a shop here in Italy, they are like the one in this picture:

http://www.jonathan.it/images/111049.jpg

Every pack include 4 complete joints at the price of 2.3 Euro. Also mini-x have ball studs with 3,8 balls, but they have a M2,5 thread instead of M2.

However I think you can easily find them in a model shop, they are sold as accessories for plane or hely links, they are quite common parts.

I've searched them on sdp-si or on the australian website but sdp doesn't have them and the other have only bigger type.

Good bye

color01
2006.01.19, 08:42 PM
i believe most of the heli accessory ball joints are made of steel... i would prefer to leave that material as a last option, though i will check and ask around next time i go to my local hobby shop.

i did some math, and all things considered, i don't have the money to build two cars. so, i'm going to move straight to the final draft. i guess i'll have to put my square rims somewhere else. anyhow, i'm going to have to start pulling out the figure sheets and calculators if i want to calculate and optimize the flex in the chassis and suspension.

http://img44.imageshack.us/img44/2937/progress089ob.jpg

4-wheel independent suspension, half-gear-half-belt drivetrain, which isn't going to be affected by suspension movement unlike the previous draft. power goes from motor > pinion > idler gear > rear diff > belt > front diff. differentials are the same size, and i'm still considering using silicone for diff plates.

suspension, i can make partially interchangeable front and rear. front bulkheads only will be 2-piece, so i can switch out the top part of the thing to change caster (0, 2, 4, and 6 degrees sounds good right?). front bulkheads will also house the front eccentric bushings (for tension adjustment). after i rework the knuckles -- the ball is once again going to be screwed/pressed into the top suspension piece -- i'll make 0.5, 1, 1.5, and 2 degree camber knuckles. front toe in, same thing, 1, 0, and -1 degrees toe in. rear toe in, 1.5, 2, and 2.5 degrees.


lots of work ahead of me.

xemet
2006.01.20, 02:21 AM
the ball studs I've purchased are made of brass, but I've seen them also made of alluminium, so I think you will not have problems with them.

This design is good, but I don't see drive shafts, and I maybe the space now can become a serious problem. By the picture I can't understand well the space beetween diffs and knuckles, specially on the pulley side. Maybe the best thing is to use the kyosho AWD drive shafts (maybe this is just your idea, I don't know), this because drive shaft are other parts really complex to be machined, and with the AWD on the market, there also a lot of beautiful alu drive shafts sold as aftermarket option parts at low cost.

Good bye

minizawd2006
2006.01.21, 05:23 AM
i will defo fund into this i will put $70 down for a chassis like that

xemet
2006.01.21, 06:23 AM
I'm not a guru, but I think a chassis like that will cost much more than 70$...

I know it...

And, remember that if you would like to make a prototype in order to test it well before selling it, that will cost you about double (and maybe more) of the definitive car that you will produce in quantity.

The fact is, if you would like to go into a business like that you've to invest money, and for money I do not intend 70 $, but 1000, 2000...

good bye.

color01
2006.01.21, 11:01 PM
realistically i'm aiming for under $500 for this first car. quite expensive, but with machining labor and extra parts... the cost is going to add up like crazy. i'm hoping to sell/give the idea to some manufacturer, with a few modifications to fit a 90-98mm wheelbase and a less exotic servo. or, if anybody knows anyone trying to start a business in the 1/28 world (who's good at marketing as well...), do tell. i'll gladly give him/her the design for free. (ok, so i might ask for a little royalty per chassis. :rolleyes: )

as for driveshafts, i'm thinking that dogbones will work, with foam spacers inside the cups to keep the dogbone in there. the xmod evo uses dogbones i believe, and i haven't heard of them falling out a lot, unless the car wasn't built right. for xemet, there is 5mm between the rear diff and the right rear knuckle; a little bit more on the left side. in the front there's about 7.5 both sides. plenty of clearance.

if it had been possible, i would have tried to design the car around the MA-010 drivetrain, but there is no way i can achieve a good CG with a shaft taking up space in the middle. thus, the diff had to be wider; thus, if i use the MA-010 axles, it will be too wide. i would gladly try to reduce cost, but not so that i compromise what i originally set out to do.

and although i haven't rendered anything new yet (it takes a good 15min, my computer's a little slow...), i am going to go back to a more 'traditional' spring-on-knuckle setup. a little math found that the ball and knuckle and two additional screws would weigh more than just a top plate, a spring, and knuckle. so the idea was nice, but i can't apply it successfully. just a note, i have MR-02 springs at home, and have designed the knuckles to fit them.

another note, the electronics are going in the empty slot i left before the leftmost battery; any ideas on how to secure them? just a regular MR-02 pcb.

xemet
2006.01.22, 02:24 AM
I will give my advice:

kyosho AWD is a nice 4wd car, only one thing really really sucks: suspensions, and all people that I've talked with, agree with me. People would like a car with real suspensions (= front and rear independent suspension with real arms and not spring on kingpins, h-plates, etc.) that is very difficult for the size. Your design was original with those plate-arms. So, if you want really sell this car, don't make an AWD with belt instead of shaft...
I think that you're too worried about weight. Yes, a decent suspension weighs more than a crappy one...but this is normal. A ferrari weighs double than a Fiat Punto...but this doesn't mean ferrari is slower. And remember that weight isn't always a negative factor.

7,5 mm aren't "plenty of clearance"...specially at the front where there is the steering movement added to the suspension movement. Dogbones are ok, the thing I was talking about is: if you go in a workshop and ask to a machinist: could you make me these dogbones (two balls with a shaft and pins mounted on them)? He will say: yes, give me 100$.
So the best thing is that you will find dogbones from other cars in the market, I don't know the xmod dogbones, and their dimension but you should check for them. However I think that 7,5 mm are not sufficient in order to steer properly.

For the eletronics, just design two plastic supports to be screwed into the chassis.

500$ are ok for the first car, I think you will not have problems. When I said 1000, 2000 I was talking of going into business, like your friend said. If you want go into business you will be asked to do 100, 200 cars, this because if you will make small quantities this is not convenient. So to make 100 cars you probably will spend 5000$...specially with this design where there are plastic parts that needs molding stamps. Of course if you will find a manufacturer that will spend the money for you that will be the best thing, but remember that the manufacturer take the risks, but he take also profits when they will came.

Good bye

color01
2006.01.22, 03:27 AM
really? well... i'm not going to argue with you, as i have absolutely no experience with any kyosho cars whatsoever. i'll stick to the carbon spring then.

i am worried about weight... a lot. unsprung weight especially, as it hampers response. if weight and friction didn't matter, i would've designed a full c-hub style suspension with adjustable upper links and lower arms. actually i did, but like you pointed out, i worry a lot with weight and friction.

dogbones are roughly the same size as xmod evolution, though i'll have to pick up an evo awd kit to check. the 'eyeball' check says that they are about the same length and ball size though, so that should work with minimal change to the design.

one more thing: i notice the xray M18 uses plastic balls of 4.1mm... semi-logical deduction says that 3.5mm delrin balls could work. what do you think, xemet? (yes, i'm being weight-obsessive again, please forgive.)

no matter what, keep the advice coming, as i'm really appreciating the large amount of feedback you've given me. :)

minizawd2006
2006.01.22, 11:13 AM
well im very interested in your design color01 as it is the first style of belt driven and i believe in my opinion that belt is better than drivshaft as 1 its quite 1 its easy to work with i like the hpi micro rs4 as its belt and dont like the m18 or wateva it is well hope we can go some where with this and hope it wont cost too much to build me a chassis if you do

xemet
2006.01.22, 01:58 PM
of course delrin ball will work, but first you've to find or make it, and second the front knuckle is one of the most solicitated part of the car so it will be easily broken.

Good bye

color01
2006.01.23, 12:35 AM
xemet, i think i have an idea that will work well with the uniball system; i can adjust camber without having to switch out knuckles. see if you can visualize what i'm trying to put across...

there are four large circles there, 2mm in diameter; a screw goes through here and clamps the ball to the suspension piece. the four smaller circles are for a pin, which is attached to the ball. since the pin is of set length away from the ball, by moving the mounting points of the pin, the ball is moved forwards or backwards. then, the user tightens up the screw to keep the camber change solid.

to reiterate, this is the top suspension piece, so by moving the circle inwards, the ball moves in, thus the top of the knuckle moves in (thus negative camber).

0 camber:
http://img22.imageshack.us/img22/986/progress09a6zb.jpg

-1 degree:
http://img22.imageshack.us/img22/4704/progress09b0pe.jpg

-2 degrees:
http://img22.imageshack.us/img22/7325/progress09c9es.jpg

-3 degrees:
http://img22.imageshack.us/img22/8819/progress09d7hb.jpg

the only compromise i have to make for this is a little more cost, and a little shorter cf spring-arm. not a bit troubling, now that i can adjust camber without disassembling the car. loosen one screw, push cf arm up, switch hole, tighten screw. i think this is a good idea. this one piece will cost more, but now i don't have to machine separate 1, 2, and 3 degree knuckles. :)

xemet
2006.01.23, 10:19 AM
Yeah, this is a good idea,
The only thing I was thinking about is the lower part of the knuckle. Is there a ball like in the upper part or only a cylindrical pin that fit into the chassis? If you change the camber (inclination of the knuckle) by moving the upper ball, there should be a joint in the lower part that allow this kind of movement. And this is true even for the normal suspension movement, even if you will not change the camber, when the knuckle moves up and down, with the ball on it attached to the upper arm, it will change its inclination and the lower joint must permit this.

I don't know what you have in mind for the lower joints of knuckles, in the model they are not shown.

Good bye

color01
2006.01.23, 05:26 PM
on the lower, i'm open to suggestions... the math says that when i change the camber, or the camber changes from suspension movement, the deflection of the bottom 'pin' of the knuckle is less than .05mm, so it's a little pointless to have a complicated articulate joint in the bottom. better off like the gen 1 xmod and just leave the hole open.

color01
2006.01.23, 06:54 PM
gah, why is there no edit button? to make things clearer, i made a little 3D sketch of the idea. props to cheezman for this camber plate thing.

this is the ball; the inside will be threaded for a 2-56 screw.

http://img69.imageshack.us/img69/9103/progress10a9ri.jpg

this is the top camber plate, so to speak. the screw goes through the oval.

http://img69.imageshack.us/img69/8213/progress10b4jc.jpg

0 degrees camber:

http://img69.imageshack.us/img69/693/progress10c0ho.jpg

-1 degrees camber:

http://img69.imageshack.us/img69/7894/progress10d3wo.jpg

so on and so forth. with each successive hole, the ball moves inwards 0.25mm, which coincidentally is exactly the distance i need to achieve 1 degree increments.

xemet
2006.01.24, 04:01 AM
for the lower I agree with you, a complex joint is not worth.

But, you've to find a compromise, because if you will make a precie hole, it is very very probable that the suspension will not work properly. If you make a hole too big, in order to allow the right movement it is probable that you will lack in precision and all the work made for the upper part in order to change the camber will be useless.

One solution (only an idea), but maybe still too complex, could be a plastic (or metal...but I think you prefer plastic ;) ) bush with a precise hole where the lower pin of the knuckle will fit, this hole should allow the up and down movement required without problems. This bush should be not solidal with the lower arms (or the chassis, I don't know if there are arms in the lower part...however if there are arms they should be not flexible like the upper), this bush should be fitted in the lower arms with an elastic collar (something like semi-hard rubber) so that it can vary its inclination a bit in order to permit the suspension movement.

Ok, I think my explanation is very difficult to undersstand due to my english...sorry, later I could make a little picture to show the concept.

good bye

color01
2006.01.25, 02:49 AM
i can understand pretty clearly, so no worries. :)

so we put a little bushing, mounted in a flexible bushing, which mounts to the fixed and rigid lower arm. that's a brilliant idea, but with a little question. if the bushing is deflected 6 degrees (say, caster), does the rubber put sufficient force on the bushing to scratch the knuckle? or is this another silly worry of mine?

but... this doesn't leave me any room for a damper plate system on the bottom of each knuckle. i wanted to do that with a semi-hard rubber disk between two horizontal slots in the lower arm.

i'll do some more brainstorming before my next post.

minizawd2006
2006.01.25, 11:13 AM
color0 u have to make this man im in on this if i can be i have money to fund

modder5
2006.01.30, 07:01 PM
HEY color0 what up. i'm from over at xmodworld.com too. nice designs lookin sweet! Over there, im portdogmc :)

color01
2006.04.12, 08:01 PM
just a screenshot of what's been going on with this project. some stuff that needed to be refined has been deleted and not replaced since i'm still not done yet. :rolleyes:

http://img132.imageshack.us/img132/3948/progress115rt.th.jpg (http://img132.imageshack.us/my.php?image=progress115rt.jpg)

what's been done:
i flipped the motor up, but seated it down lower for the same CG as before.
94mm wheelbase now.
servo has been laid down flat!
space has been found for battery holders and batteries (3mm extra both ends).
batteries moved in 3mm each side, total chassis width 46mm.
drivetrain moved 3mm to the left, motor stays in the same lateral position.
knuckle offset *will* be deep enough so that all MR-02 wheelsets can be used.
geartrain now uses 48-pitch gears for compatibility with mini-z pinions.
larger pulleys (18t vs. 16t before) for slightly better efficiency.
slightly-larger ball diff radius for better torque management.

what's going to happen:
4mm diff shaft (vs. 6mm before) for less rotational inertia.
multiple-thickness suspension spring arms (deleted, in redesign).
uniball joint for suspension (deleted, in redesign) with adjustable camber.
aluminum 'hole' for bottom pin of knuckle.
knuckle caps.
wheel axles.
belt tensioner/caster blocks.
new tierod.
upper deck.
servo hold-down frame.
new chassis baseplate with cutout for open-endbell 130. (i don't know what i'll do with closed-endbell 130's... the cutout might be a little too wide for chassis integrity.)
reverse-action air dampers. (under suspension compression, the dampers are stretched. coupled with air as the damping factor, this will make compression softer than rebound, which is a good thing.)

can't think of anything else at the moment, but any suggestions will be well taken.


i've also found a possible candidate for a machinist, a privately owned small company that specializes in precision medical equipment, and is willing to do 1-off runs. if anyone knows any others do tell.



also, a request; how long (distance marked in green) is the metal can of an Atomic BB can? millimeters if possible, down to the 0.1mm preferred. thanks!

http://img133.imageshack.us/img133/4066/motor0lw.gif