The cheap Tatra 6x6 build...hopefully
07-28-2014, 07:17 AM
#1
Thread Starter
The cheap Tatra 6x6 build...hopefully
This had been a off/and/on idea in my head for some time.
But now I finally have the core items needed to give it a real try.
I bought a pair of redcat RS10 axles with motors for $65
Then I bought a single axle and a motor for it for $35
I got a set of 5 axial ripsaw wheels for $30
Then I bought a single ripsaw wheel for $8
3 axles, 3 motors, 6 wheels = $130
I have already run the 2 axles with a simple torsion chassis and a redcat brushed ESC. So the single 27t brushed esc can handle the 2 motors. I am not sure if it can handle 3 tho. But my thinking is that a 15t capable esc should be able to hand the three 70t 390 motors.
I may have to buy some servos. I have 2 that work. Not sure if I will do just front steering, or all 3 axles or maybe just the front and rear axle. Depending on which I choose, I may have to buy a servo or 2.
The real trick will be the body and chassis. I don't want to buy links and shocks for 3 axles...this would be a bit cost increase. I did buy some 3/32 music wire which I will try to use as a torsion rod. 3' of the stuff was only $10.
I think I have a decent amount of 22 gauge sheet metal in the garage....so an attempt will be made to make the tatra's cab out of it.
I already have printed off a tatra picture that I scaled to size to match a 1.9 wheel.
My skills with metal are lacking....but the shape isn't very complicated so Im hoping I can do it and have it look decent.
If things go according to plan, I think I can make my 6x6 tatra for under $200. I am at $140 now, might have to buy a $30 ESC but hopefully have enough misc parts to do the rest.
As the build progresses I will post plenty of pics.
But now I finally have the core items needed to give it a real try.
I bought a pair of redcat RS10 axles with motors for $65
Then I bought a single axle and a motor for it for $35
I got a set of 5 axial ripsaw wheels for $30
Then I bought a single ripsaw wheel for $8
3 axles, 3 motors, 6 wheels = $130
I have already run the 2 axles with a simple torsion chassis and a redcat brushed ESC. So the single 27t brushed esc can handle the 2 motors. I am not sure if it can handle 3 tho. But my thinking is that a 15t capable esc should be able to hand the three 70t 390 motors.
I may have to buy some servos. I have 2 that work. Not sure if I will do just front steering, or all 3 axles or maybe just the front and rear axle. Depending on which I choose, I may have to buy a servo or 2.
The real trick will be the body and chassis. I don't want to buy links and shocks for 3 axles...this would be a bit cost increase. I did buy some 3/32 music wire which I will try to use as a torsion rod. 3' of the stuff was only $10.
I think I have a decent amount of 22 gauge sheet metal in the garage....so an attempt will be made to make the tatra's cab out of it.
I already have printed off a tatra picture that I scaled to size to match a 1.9 wheel.
My skills with metal are lacking....but the shape isn't very complicated so Im hoping I can do it and have it look decent.
If things go according to plan, I think I can make my 6x6 tatra for under $200. I am at $140 now, might have to buy a $30 ESC but hopefully have enough misc parts to do the rest.
As the build progresses I will post plenty of pics.
07-28-2014, 02:01 PM
#2
Thread Starter
Ok, add another $25...
I just bought some styrene materials to build a body with.
I had tried in the past to make a body with styrene sheet, it didn't go well. But this was due in part to me buying sheets that were really too thin (.40)
I just bought some .80 sheets, 1/4 square rods and 1/4 round rods (for roll bars maybe)
It seems like it shouldn't be hard, many tatra models have fairly square / simple shapes. Wont know until I get the stuff and try.
Im thinking of shooting for something like this:
I just bought some styrene materials to build a body with.
I had tried in the past to make a body with styrene sheet, it didn't go well. But this was due in part to me buying sheets that were really too thin (.40)
I just bought some .80 sheets, 1/4 square rods and 1/4 round rods (for roll bars maybe)
It seems like it shouldn't be hard, many tatra models have fairly square / simple shapes. Wont know until I get the stuff and try.
Im thinking of shooting for something like this:
07-30-2014, 05:32 PM
#3
Thread Starter
I got the music wire today.
I have a plan for the suspension layout that I think may just work.
The idea is to use solid lower links as one normally would....but in place of the upper link will be the music wire.
The upper link for the redcat axle bolts to the top/side of the axle. The bolt holes are 1'' long threw both haves of the trans case.
If I make a "L" in the music wire I can put it threw the screw hole.
I am going to try doing that, and using 1 piece for the front and 1 rear axle. The music wire will have a solid mount on the center of the chassis.
This should give each half of the music wire the job of controlling twist of the axle (since the "L" will make the music wire have to twist as the axles does)
I think the music wire will have enough stiffness to control the axles back/forth twist that a normal solid upper link would control.
The wire should also allow the axle to move up and down....but within a limited range. I am just hoping it will be within the range I want.
The redcat axle's have 2 holes for the upper links' mount. So, on the 2 rear axles I will have a second piece of music wire joining the 2 as a upper link for the rear axle. Not 100% sure this can work...may allow too much flex and give. But if it does work, it will be a very simple layout.
tried to draw a simple "top down pic"
black is chassis
blue is music wire
brown is solid links.
I have a plan for the suspension layout that I think may just work.
The idea is to use solid lower links as one normally would....but in place of the upper link will be the music wire.
The upper link for the redcat axle bolts to the top/side of the axle. The bolt holes are 1'' long threw both haves of the trans case.
If I make a "L" in the music wire I can put it threw the screw hole.
I am going to try doing that, and using 1 piece for the front and 1 rear axle. The music wire will have a solid mount on the center of the chassis.
This should give each half of the music wire the job of controlling twist of the axle (since the "L" will make the music wire have to twist as the axles does)
I think the music wire will have enough stiffness to control the axles back/forth twist that a normal solid upper link would control.
The wire should also allow the axle to move up and down....but within a limited range. I am just hoping it will be within the range I want.
The redcat axle's have 2 holes for the upper links' mount. So, on the 2 rear axles I will have a second piece of music wire joining the 2 as a upper link for the rear axle. Not 100% sure this can work...may allow too much flex and give. But if it does work, it will be a very simple layout.
tried to draw a simple "top down pic"
black is chassis
blue is music wire
brown is solid links.
08-01-2014, 04:28 PM
#5
Thread Starter
Im struggling with how to do the suspension. I found a very cool and very simple way to use the music rod as suspension material....but not sure how to adapt it to the redcat axle.
The picture below shows it on a kyosho mad force axle. This axle is flat and has tabs that made adding the metal sides and delrin top plate fairly easy. The rods then go threw the delrin plate and act as the upper, lower links and the shocks....all in one!
But the redcat axles are MOA and have a lot in the way. I may need to mount a delrin plate off of the servo mount. The 2 holes for the upper link mount could work, but im not sure how to use the those to mount a delrin plate from those.
But if I can duplicate this design with the redcat axles, I will have a simple and compact suspension.
08-03-2014, 02:50 PM
#6
Based on the pics I could find of the axle my only guess would be screw a piece into the servo mount position, and mount a servo higher up.
For the other side you could probably bend a piece of metal to make an L-bracket with some longer screws that screws into the screw holes that hold the cover to what I'm guessing is the spur gear together that I can see.
Now that idea would work insanely well with WK axles as no modding would need to be done at all.
Its an interesting idea though
For the other side you could probably bend a piece of metal to make an L-bracket with some longer screws that screws into the screw holes that hold the cover to what I'm guessing is the spur gear together that I can see.
Now that idea would work insanely well with WK axles as no modding would need to be done at all.
Its an interesting idea though
Last edited by SyCo_VeNoM; 08-03-2014 at 02:53 PM.
08-03-2014, 03:33 PM
#7
Thread Starter
Ive been re-thinking the torsion rod setup.I have figured out a way to adapt it to the rs10 axles...however this would have the rods up where the upper link mount is.
The problem with that (maybe a problem) is that the mounting would be high above the center of the axle.
With a shaft driven axle, you can mount the rods about 1 inch above the axis of the axle.
On the redcat axles, I would be about 3 inches of the axis (because of the transmission and the fact that the axle tubes are angled)I fear this would cause more twisting force (back and forward) on the torsion rods then you would get with them mounted closer to the axle. With the rods close to the axis, I think they can handle the job of upper, lower link and shocks. But with them higher up, I think they will have trouble doing the job of the upper link.
I might still try this on the rear-most axle, but am currently thinking of making a regular torsion "stick" for the front 2 axles. I think I can mount the stick to the main chassis plate and still have flex, but mounting it with some O rings as spacers.I am finding using these axles to be a big pain.
Between the trans case, motor and lack of a shock mount (stock, the shocks mounted to the lower links) I feel limited in my options. If I had a way to machine parts, it wouldn't be too hard. But trying to come up with a solution when I only have a drill, hack saw and screw driver is proving difficult.
I will still work on a torsion type setup. I feel this will be a big advantage as a scale tatra shouldn't have a lot of flex and not having lower links will greatly increase the ground clearance.
The problem with that (maybe a problem) is that the mounting would be high above the center of the axle.
With a shaft driven axle, you can mount the rods about 1 inch above the axis of the axle.
On the redcat axles, I would be about 3 inches of the axis (because of the transmission and the fact that the axle tubes are angled)I fear this would cause more twisting force (back and forward) on the torsion rods then you would get with them mounted closer to the axle. With the rods close to the axis, I think they can handle the job of upper, lower link and shocks. But with them higher up, I think they will have trouble doing the job of the upper link.
I might still try this on the rear-most axle, but am currently thinking of making a regular torsion "stick" for the front 2 axles. I think I can mount the stick to the main chassis plate and still have flex, but mounting it with some O rings as spacers.I am finding using these axles to be a big pain.
Between the trans case, motor and lack of a shock mount (stock, the shocks mounted to the lower links) I feel limited in my options. If I had a way to machine parts, it wouldn't be too hard. But trying to come up with a solution when I only have a drill, hack saw and screw driver is proving difficult.
I will still work on a torsion type setup. I feel this will be a big advantage as a scale tatra shouldn't have a lot of flex and not having lower links will greatly increase the ground clearance.
08-09-2014, 06:22 PM
#8
Thread Starter
well, after much head scratching I have finally come up with something that should work.
I will try to explain the pics below.
The center "L" aluminum bar, which goes between the front and center axles is a standard torsion chassis kinda setup. I tried having it extend to the rear most axle, but the short distance between the 2 meant there was very little flex.
So, now I have prototyped the main chassis rails (which all the body parts will mount to) which attach to the center torsion bar via 2 cross plates. These plates are placed somewhat close together so as to not stiffen up the torsion bar.
Then, the rear axles is flipped so that 2 lower links can go between the two rear axles...and 2 upper links can mount to the rails (they will be moved tho, and attach to the cross plate)
I found I need to make another set of cross plates which are 1'' wider as the rear most axle's motor hits the side rail. I also failed to get the center hole "on center" with these first set of cross plates.
So, once I make new, wider cross plates with better centered holes, then I will just have to figure out how to mount some shocks to the rear most axle.
On the front of the chassis, I may use some camber links to go between the torsion bar and the chassis rails....just to give some strength to the setup without reducing the twist allowed by the torsion bar.
This setup is still more complicated than I wanted, but these redcat axles with their large trans case and funky (and few) mounting points limited my options. Using a torsion rod was the simplest options, but couldn't be used on all 3 axles. Connecting the last axle via upper and lower links was the only option really.
The upside is the torsion rod means the ground clearance between the front and center axle is very high....no links or shocks to get in the way.
It will be kinda weird having the chassis rails "floating" over the front axle, but using a cross plate in the front would prevent the torsion rod from twisting at all. And the rod provides plenty of side-to-side and lateral rigidity on its own.
The torsion rod is mounted to the axles via the upper link mount holes. Then, I added a camber link between one of the trans case' screw holes and the torsion rod, to add strength and prevent stress from ripping the screws out of the upper link holes.
Once the new cross plates are made, mounted and I figure out how to mount a pair of shocks for the rear most axle, I will be ready to start on the tatra body!
I will try to explain the pics below.
The center "L" aluminum bar, which goes between the front and center axles is a standard torsion chassis kinda setup. I tried having it extend to the rear most axle, but the short distance between the 2 meant there was very little flex.
So, now I have prototyped the main chassis rails (which all the body parts will mount to) which attach to the center torsion bar via 2 cross plates. These plates are placed somewhat close together so as to not stiffen up the torsion bar.
Then, the rear axles is flipped so that 2 lower links can go between the two rear axles...and 2 upper links can mount to the rails (they will be moved tho, and attach to the cross plate)
I found I need to make another set of cross plates which are 1'' wider as the rear most axle's motor hits the side rail. I also failed to get the center hole "on center" with these first set of cross plates.
So, once I make new, wider cross plates with better centered holes, then I will just have to figure out how to mount some shocks to the rear most axle.
On the front of the chassis, I may use some camber links to go between the torsion bar and the chassis rails....just to give some strength to the setup without reducing the twist allowed by the torsion bar.
This setup is still more complicated than I wanted, but these redcat axles with their large trans case and funky (and few) mounting points limited my options. Using a torsion rod was the simplest options, but couldn't be used on all 3 axles. Connecting the last axle via upper and lower links was the only option really.
The upside is the torsion rod means the ground clearance between the front and center axle is very high....no links or shocks to get in the way.
It will be kinda weird having the chassis rails "floating" over the front axle, but using a cross plate in the front would prevent the torsion rod from twisting at all. And the rod provides plenty of side-to-side and lateral rigidity on its own.
The torsion rod is mounted to the axles via the upper link mount holes. Then, I added a camber link between one of the trans case' screw holes and the torsion rod, to add strength and prevent stress from ripping the screws out of the upper link holes.
Once the new cross plates are made, mounted and I figure out how to mount a pair of shocks for the rear most axle, I will be ready to start on the tatra body!
