Didumos69

[MOC] Greyhound 4WD RC Buggy /w instructions - Improved rim-hub connection

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On 3/28/2019 at 5:37 AM, Woodstock89 said:

Я наконец нашел время и сумел доделать эту великолепную машину. Это действительно шедевр, и мне понравилось его создавать. Я выбрал черно-красную цветовую гамму и улучшенные диски.

Greyhound_1.jpg 

Greyhound_2.jpg

 

Hey.
I also chose these colors.

1.jpg

Edited by crooked_2

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@crooked_2 На этом форуме разрешен только английский.

Please, speak English only. Congrats with building this awesomw buggy!

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8 hours ago, Aleh said:

@crooked_2 На этом форуме разрешен только английский.

Please, speak English only. Congrats with building this awesomw buggy!

Hello
Thanks for the help.
Fascinated by the design abilities of Didumos69.
I first assembled the model in August using an LDD file.
Then I bought the instructions. I collected the model 4 times already.
I have not figured out yet how to thank.
And my language is not very. I use translator.
Easier German.

More photos at https://bricksafe.com/pages/Sergej
I have a limit of 0.1MB here.

Edited by crooked_2

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14 hours ago, gregorski904 said:

Stickers and latest wheel design

Very cool! With the new wheel design the tires seem to fit excellently :thumbup:

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Hi guys i litterally just created an account so see if you guys can help me with some things with this model. 

First off to the designer, this model is beautiful ive been looking for years for a 4wd rc buggy that looks beasty and can actually handle some actual off-road obstacles. Great work.

now ive ordered some custom LEDs for the lights as well as a POV camera that i am going to be adding to the model.

i saw that some guys here have used tiers that arent technic tiers, and look to be made for the gas powered rock crawler market. I was wondering if someone could help me understand how i could go about purchasing some of those tiers like with sizes or what i need to get.

Thanks guys hope to add a few pictures after i get everything built. 

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Posted (edited)

Looking for help, either from didumos, or from the collective.

I have built greyhound and it's awesome. Not awesome like a hotdog, but awesome like the universe (Eddie Izzard joke).

Within the first few minutes though, it spat out its first universal joint. Turns out I don't have any spares, but I do have some CV joints which 42099 didn't mind donating.

Greyhound

It fits!

Greyhound

And if you reverse the rim, it works. However... Then you have only half a stud connection into the wheel's axle hole, and enough slack between the rim and the turntable that makes it wobble like you've got your lug nuts fitted finger tight on your real car.

What I really need is that red connector with an axle hole in the middle so the CV axle would drive the turntable hub.

Greyhound

But that's not a thing. What I did was this:

Greyhound

With the two rubber bands which were on the universal joint wrapped around, it seems to be holding. Maybe it even gives a cushioning effect, like a sprocket cush rubber on a motorcycle?

 

So, to my question:

Can this be done with a more legitimate connection between the driving axle and the turntable?

 

Ps: Apologies for big pictures. Working on mobile, will try and resize on PC.

Edited by amorti

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Just now, astyanax said:

@amorti is the turning radius affected at all?

I'm still testing it for durability, but it works fine.

Worst case scenario, you can program the buwizz to steer a little less tightly.

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I just tried putting the long female CV joint from 42099 into the hub, with the red #2 connector in between, and it actually extends fully into the wheel's axle hole. So from what you're saying, it sounds like the female CV joint is (slightly) coming out of the wheel when driving?

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Posted (edited)

I guess you put the female (axle hole) end to the motor as I did, because the male (axle) side doesn't reach the motor.

You end up with an axle pointing to the wheel.

If you put the wheel the same side out as didumos, the axle doesn't reach the axle hole in the wheel.

If you put the wheel the other side out, you'll get half a stud of connection into the wheel, but also a little play between wheel and turntable, enough that the whole thing shakes.

The wheels I have are same as from 42099. The 2L wheel centre hub has an axle hole but only half way through it. If you put the wheel the way out if needs to be (this side against the turntable) you don't reach a crosshole.

15038-0-8b645e8c-6a8a-4110-baa0-9cc85583

Are there wheels which fit those tyres, but with an axle hole the full way through? Ideally in black.

Edited by amorti

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1 hour ago, amorti said:

Greyhound

Ah I think I get it. What I meant was that, in this picture, the female part (in darker gray) can be pushed further into the red #2 connector -- further inside the wheel. If you push it all the way, its axle will go fully through the wheels axle hole. But I think your point is, that this cannot be done, because then the pivot point would be too far inside the wheel...

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Obviously, the pivot point would have to be between the ball joints, or you need extra pivots in the axle which seems undesirable.

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Posted (edited)
48 minutes ago, pleegwat said:

Obviously, the pivot point would have to be between the ball joints, or you need extra pivots in the axle which seems undesirable.

+1 on the point

+1 on the obviously

Putting legal and illegal builds to the side (yes I'm aware it's a shame on a didumos build), how would one go about obtaining one of those red connectors with an axle hole in the middle, and maybe 1L of axle either end? Must be possible to 3d print something of the same rough shape, but what about material strength and fit tolerance?

Or is there a claas tyre compatible wheel with an axle hole right the way through?

Edited by amorti

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Posted (edited)
2 hours ago, amorti said:

If you put the wheel the other side out, you'll get half a stud of connection into the wheel, but also a little play between wheel and turntable, enough that the whole thing shakes.

That's simply due to part 6553. Need to get rid of those. How about so:

https://www.dropbox.com/s/o8en6862ge5jreo/hub0.jpg?dl=0

https://www.dropbox.com/s/h9p5ex2q7odn2ko/hub1.jpg?dl=0

Edited by astyanax
URL formatting

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Posted (edited)

Pulley wheels - that's exactly what I wasn't thinking about. Nice one!

Leaves me wishing for a half stud thickness pin connector / washer, but yes I think that would do it. Gives you half a stud of axle connection from the pulley wheel into the turntable plus half a stud direct into the wheel rim, while helping centre the whole lot.

Doesn't give anywhere to anchor the two yellow half bushes outside the rim which set the clamping distance like 6553 does, but if no other solution offers itself I'm pretty sure those would just stay by laying them in the "lugnut" hole.

Edited by amorti

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What's this orange/brown pulley wheel called? Spotted it in a group listing and I think it'd fix even more points than a pulley wheel.

https://photos.app.goo.gl/jBbWMHvqxGoiTMPT7

Dangit, it's a whole stud thick. They've left the bottom part of the male CV shaft round (to reduce friction?), so that's out.

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7 hours ago, amorti said:

Pulley wheels - that's exactly what I wasn't thinking about. Nice one!

Leaves me wishing for a half stud thickness pin connector / washer, but yes I think that would do it. Gives you half a stud of axle connection from the pulley wheel into the turntable plus half a stud direct into the wheel rim, while helping centre the whole lot.

Doesn't give anywhere to anchor the two yellow half bushes outside the rim which set the clamping distance like 6553 does, but if no other solution offers itself I'm pretty sure those would just stay by laying them in the "lugnut" hole.

If you insist on retaining the half-bushes, simply replace my blue 3L pins by 4L axles, fix them with those half-bushes on the outer side, and fix them with a thin 3L beam on the inner side (on top of the pulley wheel). Another pair of half-bushes can be used inside the contraption.

7 hours ago, amorti said:

What's this orange/brown pulley wheel called? Spotted it in a group listing and I think it'd fix even more points than a pulley wheel.

https://photos.app.goo.gl/jBbWMHvqxGoiTMPT7

Dangit, it's a whole stud thick. They've left the bottom part of the male CV shaft round (to reduce friction?), so that's out.

https://rebrickable.com/parts/98585/hero-factory-weapon-barrel-with-2-pin-holes-and-3-axle-holes/

I considered that, but indeed it won't fit.

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Posted (edited)
28 minutes ago, astyanax said:

If you insist on retaining the half-bushes, simply replace my blue 3L pins by 4L axles, fix them with those half-bushes on the outer side, and fix them with a thin 3L beam on the inner side (on top of the pulley wheel). Another pair of half-bushes can be used inside the contraption.

https://rebrickable.com/parts/98585/hero-factory-weapon-barrel-with-2-pin-holes-and-3-axle-holes/

I considered that, but indeed it won't fit.

Yep, in the meantime I'd thought about using 4L axles with stops, up through the bottom. I hadn't thought of a 3L beam, that's good as it would slip over the plain round part of the CV joint and anchor the axles.

Those yellow half bushes outside the rim are to keep the wheel tight against the turntable.  I think it will be loose without them, although there may be enough stabilisation from that double pin/axle connector in the middle.

Like the use of "contraption". These hubs were already complex and not trivial to construct. This is going to be even more interesting!

Edited by amorti

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Posted (edited)

I have been driving the model a bit using the solution above, which works but doesn't have much to keep the CV joints centred in the hubs. As a result the CV joints are pretty worn on the softer half.

800x800.jpg

Chewed up, but not spat out. I'm pretty sure it would've spat out another universal joint by now as I've not been going easy on it.

The pulley wheels arrived for me to try the other method described by @astyanax. Goes together like this:

800x957.jpg

800x931.jpg

800x800.jpg

The idea to use 4L axles with end stop won't work, the end stop doesn't fit and interferes with the parts behind it. Doesn't matter though. Even if the axle got loose, it has nowhere to go and would just nudge itself back in as it span.

After that it's the normal construction, just stick a 3L axle in from outside the wheel to centre the double pin connector thingy.

I haven't driven it this way yet, but it's clear from just manipulating it that the CV joint is much better centred, which will definitely help it live longer.

Edited by amorti

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Just now, amorti said:

I haven't driven it this way yet, but it's clear from just manipulating it that the CV joint is much better centred, which will definitely help it live longer.

Very interested to know how this works -- didn't get around to trying it myself yet. Do these CV joints affect the max steering angle?

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