GoMeR23

GoMeR23

hey guys! so im new to the forum, i've been following some of the projects on here, and i've been inspired to build my own 1/4 scale rc! so far i have a parts scooter, engine., wheels, brake, and some metal. im thinking i will do a sandrail, with trailing rear suspension, and long travel front wishbone suspension. im building every part custom., including the shocks.

kenazzo2000

nice keep us updated and plenty of pic please good luck

GoMeR23

here is some pictures so far! i have some ball joints, and some impact driver universal joints for the driveshafts. i still need to make some h bridges for the servos, i will probably use drill gearboxes, for both throttle and brake servos. i have an idea for the differential, i will try to make a limited slip ball differential, by using a thrust needle bearing, with both axles being pressed against it on either side. i will get some pics of that hopefuly soon! i may have to string this project out over a little while. im a little short on funds these days.

kenazzo2000

youll get it ready one day these projects do take time i know mate

Dirty_Vinylpusher

Wow.
I like the look of this.

GoMeR23

http://i270.photobucket.com/albums/j...-28_111727.jpg
So here is my rear wheel drive axle design, im using stancard skateboard bearings because they are more easily available.

GoMeR23

And next to the wheel. I will weld a triangle plate between the two set screw collars and bolt that to the wheel. By the way, does anyone know if chrome vanadium can be welded to steel?

GoMeR23

Some mock up drawings of the rear end.

GoMeR23

So here is a mock up drawing of the frame design, and my steering setup. Its a rack and pinion type design, I will weld a peice of chain to the square tubing, and have that sprocket drive it.

Lars from Norway

Got to like this, i see some new thinking here, which is nice!

GoMeR23

More frame design.

GoMeR23

Ok so updates. I finally got a working h bridge together! It uses a cheap futaba s3003 servo rather than ruin a digital one.
I found a site that shows you how to find the pwm signal on a servo before ot goes into the servos h bridge.


I also started thinking about the suspension, im leaning towards using copper pipe, with thread adapters soldered ontothe
Ends and using putting an oring between two threaded reducers to seal the bottom.

GoMeR23

http://youtu.be/hsqJuuu5UjQ
Here is a video of the h bridge running a small motor at about 9.6 volts.

GoMeR23

so i found a better idea for the suspension, instead of a stupid peice of galvanized steel, i chopped up a steering tube from a bike.
its smooth, and has threads and a threaded collar and cap for the end which i only have to weld a washer to the end of. i got the
rear bearing tube figured out, the bearings are a little loose in there, but i can weld a few spots on the inside to tighten it up.

Dirty_Vinylpusher

Steering tube...
Brilliant idea!

GoMeR23

So I have changed my mind again about the design of the shocks. I was going to use rubber grommets in the end to seal the shafts, but irealized they seem to have too much play, and will leak under the slightest load. So im trying a thteaded, hollow hose connector that is 1/4 inside diameter, bolted to the end of the shock. I will put an o ring over the shaft and screw the end cap on to seal it.

GoMeR23

So I'm trying to design all the drive train and suspension systems before I build the frame around it all. For the transmission I'm using a an angle grinder head so I can mount the engine in the center of the frame for better balance.

GoMeR23

Huge update time! I have started the frame! I must say I'm pretty happy with it so far! One setback though, it turns out the bike tube is tapered inside, so the piston won't slide in there though.... Anyone have any experience with bikes that can tell me if all bikes are like that?

GoMeR23

So this is the almost finished shock, I just need to figure out what to do about the tapered tube. I may have to find another bike to thief o
Another steering tube from and see if those are tapered too.....

Dirty_Vinylpusher

Hmm..... I've tinkered around a fair bit with bikes but can't say I've even noticed that the steering tube is tapered.....




I like the look of that frame though!
[8D]

GoMeR23

Ok I lied, the tube isn't tapered, its just thinner on top and goes thicker half way down the tube. That still does not solve anything though. I may have to just cut it in half anf weld a thinner tube to the end to finish the shock tube. I'm not sure I have the welding skills to make a clean solid weld like that though. I will probably have to bag the bike tube, and use the same metal I'm using for the rear bearing carriers and make aend cap I can slide in the end and secure with set screws.

GoMeR23

Alright im way bummed out but i have to bag the bike tube idea. i cant fix the tapered tube issue without a lathe or some kind of tool for that. but i have decided to use the same size of metal, (which i bought alot of earlier) with a jam nut welded to the end, and a washer welded to a spacer, and bolted on four sides for the top end. I really liked the threaded tube, but what can ya do....



so here is an exploded view of the shock. All made from parts you can get at a hardware store. including metal, and springs. i made the piston from a peice of lexan plate, that is how i found out the tube was tapered, because it stopped halfway up the tube! so i need to make another one on my drill press. aka the poor mans lathe.

Dirty_Vinylpusher

Poor man's lathe, I used to do that too before I bought my lathe.





Are you SURE the tube is tapered on the inside....?
One thing that springs to mind is that it could be deformed from the tightening of the handlebars.

See the little shiny part in this pic?



That's what holds the stem in place by wedging itself against the inner part of the tube.



Anyway, seems like you've got it sorted out.

GoMeR23

Good point. But the thing is, its tapered so the top by the threads is thinner and halfway down it gets thicker.if it was deforming it wouldnt he bottom be thinner?ithink they are designed that way for strength. it kind of triangulates the tube so it can deal with the side forces it needs to. I would just weld the threaded part to a new tube, but its too hardto be that accurate with an arc welder.... Im not that skilled yet.