Noizy Cricket the sprint build to Eurocrawl

[xkill]

About a month and a half to go to Eurocrawl I decide that I was adapting my axles project ( New axles project - XK - A1 ), and make a 2.2s.
Like this I could enjoy more time on the rocks!
The catch was that I only had half build axles, a 2 year old demanding daughter and a wife that would be delivering our second child in this time frame!

As far as electronics I only had to buy a BEC because the FXR, Hitec 7950 and receiver were already at home. Even if it was not necessary I also scored a Brood Vapor that was used.

I designed a gearbox to use what I had at home, Bully V1 gears.
This was designed to use with axial axles... What I was using had much lower gearing.

Gearbox was 3d printed:







A custom shaft had to be made and another one changed. This was the first part I ever made in a lathe!
To make the pin hole this was all I had...



It took me a few tries but I got a straight hole!
Half way done



In it's place:


I finished the shafts on the rear axle.
The way they are I have zero slop!



85% finished rear. Missing hubs and under protection.





Front shafts are cheap 1/8TT OFNA style that were grinded down.



Everything was brased in place.



This was also my first go at brasing...



I was also using some Bolly v1 knuckles that I had to cut.
My dremel was working extra time!!



Almost done...



Rear hubs were printed



For the chassis I wanted to go with something different.
Central motor and a skid as small as I could make it.
The meant that the shaft would go in the side of the chassis plate.





3d printed a skid for the chassis



Rear hubs were also ready



An acrylic version of the chassis was cut so I could do links and test fit.











Little more than 24h before the departure to Eurocrawl and this was how the car was looking...



Final assembly has no pictures...
I worked all day and all night on the car... Managed to finish the car, put some electronics, had 1.5h of sleep and off I went to Eurocrawl!

[xkill]

The rig was fired up so I could set up the servo the night before the comp.
It was VERY LOUD because the gear mesh on the 32pitch gears of the gearbox is not good. They only touch on the tip of the gears...
Besides this, it is VERY SLOWWW!!!

I the morning I put the body on and off I went to tech the car.
The body was way too short!! I didn't have time to ready and rules and just took what I had...
One beer later...





It looked like crap but at least I could comp it!
My group was Samu, Sofi and 2 other Portuguese.

Getting ready for Course 1



Started to go and smiles all around! Damn that's a noisy rig!!!





Style!!



One thing is for sure, there's plenty of torque!!







Course 1 was finished and it went great! -4 points.
The rig is super slow but it is very very predictable!
One thing that helps is that I have 25:1 on the front axle and 40:1 on the rear. The only downside is that I have to be extra careful with reverse's...
Had a laugh and drank another beer for celebration!

Second course went even better! -8 points.









Things got even more exciting when I got a -17 on course 3!!
At this point I'd run out of "celebration beers"...





Things were looking pretty good but the I stuffed it on course 4 and got 22 points...



Course 5 was better and got -7

On the final course, course 6, I was doing great up to gate 5 then I took 2 role over's and a re-position.. The got to gate 7 I think and ran out of time... In the end, 26 points...

End result, 14 out of 28 drivers, with a car that had 0 testing and me driving for the first time a 2.2s rig!
Epic win on my book!!

Final toughs:
OD/UD is great!
Top speed sux as I was full throttle about 85/90% of the time...
Only had one problem because the bottom cover for the rear axle was not resistant enough (I was already expecting this but ran out of time to make anything better...)

Front was fine:


Rear broke but ducked take saved the day!



I was using 850 mha batteries and they with be +/-3.7v per cell after one course. This was great as run time was a concern.
With the 5min courses the electronics would get a bit warm but nothing major, the batteries were getting the warmest...

In the end some friends were testing the rig and battery got really hot!!!
Conclusion: Only run this rig for 5min, no more than that!!!

On yes, did I mention it is very very noisy?





Unfortunately, I don't think there's any video of it...

[xkill]

These axles will now for sure be living a 2.2s life!
I already have plans to make a different case for the worm gears, and also a new gearbox, probably made with pinions.
I just need to get some time and star working on Solidworks...

[crawl-o-matic]

How did it handle?

[xkill]

Long story short:
It went great!!

14 place out of 28 of the best in Europe!!

[Del Monte]

What a creative build! That definitely took some out of the box thinking.

Your first problem is that you ran out of celebration beers

[EeePee]

Always bring enough celebration beers!

[xkill]

For sure that was my main problem!
Next time I'll be better prepared beer wise, of course, the car part is good enough!

We'll see how this evolves...

[skypyt]

congratulations for this crap rig ;) with nice setup!

this one of the stories of Portuguese Team at Eurocrawler

[xkill]

Thanks!
It beat your crapy rig so that's fine with me!!

Got this on a scale and RTR weight is 1694g with a perfect (to me), 65/35 weight bias!
Some call it lucky, I just call it good planing!
Hahahahah!!

[truespace]

Hey,

I like that rig look like built in a mad max movie
and i appreciate a lot the awesome work on axles

Do you have any link for inserts you use ?

Truespace

[xkill]

Sorry for the late reply!
I got the inserts from ebay (Italian seller).

100 Inserti Filettati A Pressione M3 Ottone x Legno Plastica Threated Inserts | eBay

I bought these because I wanted to get rid of the imperial screws on VP hubs... I was stripping the aluminum screws too often.
I made some 3D printed hubs and put these inserts.
It works great!

[xkill]

Noisy Cricket just got the first of it's revisions!

I just got the center the worm gear re-designed and now it much much better!
Why didn't I make it like this the first time?!

3d part:



Was trying to dye the parts but failed, I guess the dye is not good for this...



Got to love some cnc action!!



Rear model:



Front



V1.0 vs V1.1







On the rear:



And the front:



Now I have more ground clearance, a simpler and more robust setup, and a round edge instead of a strait edge (I was never a fan of strait edge, I like beer too much!)

Some pics with the old setup after the trip to EC







The slim skid is the objective of this chassis design.





Next thing on the agenda, more wheel speed!
This gearbox was initially thought to use with Axial axles, not 25:1 worm gears...

[xkill]

The action this car lacks on the rocks more than compensates on the bench!

Since Eurocralw it went to the rocks once, and it broke in 2minutes!!
Some might say I got lucky that I finished all courses on EC, I just say this car was engineered like a F1, strong enough to last one event and then rebuild!

Anyway, it broke a bearing.
I knew the bearings were not a good option because they are not designed to work like that, especially with the forces involved. But I wanted to know how long they would last (not very long...).
I already had bushings ready to go so it was an easy fix.





My hobby room was messy after the sprint to finish the car to EC, and I didn't have time to make it any better....



The shapeways parts compress too much... They distort more than I would like.
I made this spacers to try and fix that problem. It was much better, but not perfect (the spacers length is not perfect, I would kill for a lathe!! ).



After that I wanted to seal of the bottom of the axles (you can also see one the bushings that replaced the bearings).



And also the servo...



The car went to EC with Rovers on the front (on 0.7'' wheels), because the taller voodoo's were rubbing too much... Even the Rovers were rubbing a lot...
To fix that I had to inboard the front lower links, as well as the shocks.
But to accomplish that I had to move the servo!
And this meant also finding a new place for the batterys!!!

So this is the new servo placement!





Now I don't have any rubbing with the voodoos!
If you notice I also inboard the plates on the chassis, allowing me to have more room for the shocks.



To inboard the shocks I had to cut some CF plates to mount on the existing (3d printed), shocks mounts.



A bit too much separation but I guess I have to live with it...



So now I have to make another under tray for the front so I can mount the battery. I will be using 450mha batterys instead of the 850mha I used in EC.
This tray (hopefully), will also allow me to move the electronics from the chassis to the tray, this will lower my CG a bit more.

Maybe one of these days the pinions I ordered from HobbyKing will show up and I will be able to make a new gearbox with faster ratio...

Stay tuned!

[xkill]

Noisy Cricket rides again!!!
And this time noisier than ever!!

I'm testing a brushless outrunner.
With 1250kv I think it's even slower then before, and for sure more noisy.... Battery live sux too... 8min out of 1000mha bat!
The upside is that all the electronics were nice and cool, unlike with the brushed setup!

I wasn't running a BEC so I wasn't pushing the servo too much...

Enjoy, with ear plugs!!!

[xkill]

Building a new gearbox for this project.
It will be much faster for sure, let's see how it will be torque wise...



The last time this car was used it stripped the rear worm gears.
I think I can make the gear mesh tighter and test again.

[xkill]

New box is done.
Man, the difference a proper gear mesh makes...Axles are next but I'm not sure I'll be able to print them at home...

I suppose I'll have to change its name!


Oh and the ABS changes color with temperature!
Left is cold right is hot, straight out of the printer ;)
It's nice to keep an eye on the temperature.

[Natedog]

AWESOME, love all the 3d printed parts, your thinking and coming up with different stuff. Congrats on your comp and keep this thread updated!

[Natedog]

What's new, whats' cooking, what's 3D printing Xkill Cricket?