Maslin's Bomber Not-Ready-To-Run Build

[terrible]

I'm working out a steering rod type servo-saver. Something that woudl just look like a normal link from the servo to the knuckle but have a spring with adjustable pre-load and your choice of spring.

Sick of killing servos and breaking links myself.

[generalee7]

I hear ya on breaking shit. I bought a supposedly good servo from a reputable source and broke it on the first run. Ridiculous so I put a Hitec 7950 back in and started breaking servo cases. Turns out I was just pushing the limits of it so I bought a Tenno truggy I can really beat on and dedicated the Bomber to crawling duty and its been great! Now I have the best of both worlds and am not breaking shit every trip out

[Erik D_lux]

The biggest problem with the servos breaking on the Wraith/Bomber setups is the short steering arms on the knuckles.

As you may already know, the longer the servo horn is, the weaker the servo will be. This also applies to the steering arms on the knuckles. The longer the steering arm, the STRONGER the steering will be and therefore, the stronger the servo will be.

The way the servo is typically oriented on the Wraith/Bomber can also be a problem. Since they are not efficient due to the way they are mounted, they need a longer servo horn to get full steering. Again, this will get you a weaker servo. The caveat to this is that if you happen to hit something with the wheels at 50% of their throw, it will be so inefficient that it will have some give. If its at 0 throw or full throw, its not so forgiving. This is one thing that can make my truss a better or worse setup. If you dont tune in the servo horn for the optimum length, my truss will actually stress servos more because they are more efficient with the steering throw and dont have that "slop" if you want to call it that.

Looks like youre all dialed in for your servo placement, not a whole lot you can do about that. But you could try some longer steering arms if you can get the throw out of your servo with new ones on.

This is why a lot of guys are having better luck with servos when they run my truss and knuckles. I run about a 1" long steering arms on my knuckles BTW.

[Correll]

Originally Posted by maslin

Killed the H50B, maybe 2 hours on it? Pics coming soon, something inside stripped.


Separated the first gear and bent the shaft bad. Not sure how that even happens, it's captured at the top and bottom





They aren't lying, helical gears for sure.

Guess its my fault you broke this. The first thing out of my mouth when you walked over to show me how fancy it was, "you'll break it"...
I knew this was gonna be in your thread, when I opened your parts cabinet to get a tool yesterday I saw just your front axle sitting there with an exploded servo attached...F@*K.

See ya Tuesday Sprinter Master!

[maslin]

Awesome customer service from Taildragger RC, I'm sending my broken servo in and he'll be sending out a new one. He said his parts supply on these is pretty limited, exactly what I found looking for parts myself.

In the mean time, put another case on the old trusty 1283 (case #3) and installed that with the VP servo mount. Much cleaner install, the fewer parts the better. I'll probably just stick the H50B in a drawer until the 1283 breaks.

[DenisLM]

I'm linking the 1283 so much lately. so many crashes and rolls, other broken parts (rod ends, servo mount) but the servo itself still strong. Only you to break it.

Also the reversed VP servo mount is great too.

[maslin]

Let's look at servo gears a bit. With all the abuse I've thrown at my Savox servos, I've never had a gear failure. I was cracking 1230sg cases down the middle on a regular basis, and have broken the ears off of two 1283 cases. The Savox gear set up is different than every other servo I've had apart, they've figured something out.



Most notably, the first gear off the motor does not have a large ratio, 2-1 or so? Compare that to the first gear in the h50b servo (which I separated within one battery,) the ratio is much much higher, 4 or 5 to 1.



The gearing from the motor to the output is all up. Driven big gear, small gear out. The h50b uses 4 gears, the last being a single gear with the output. The 1283sg uses one more gear at the end, 5 gears total.

h50b



1283sg



When force is applied back through the gears, say hitting a rock, the gearing is all down. The mechanical advantage applied at that last gear is massive, especially with such a high ratio. The Savox gears in general have a closer ratio, with one additional gear which results in a similar overall ratio. The strength of a tiny gear pressed in to a huge gear is minimal, a medium gear pressed to a large gear is much stronger. Hitec and other brands seem to use the 4 gear, huge to tiny principal. Even a high end Protek 170t, the setup is identical to Hitec.

This gear arrangement seems to be fairly unique to Savox, and I feel is the reason I have not had any gear issues in 3+ years. All that being said... I'm not an engineer, if I'm wrong, point it out. Forums are for sharing knowledge, let's get that back.

[Correll]

I work right next to this guy, and I was unaware of all of this. That's good tech Maslin!

[maslin]

The 1230 uses the same 4 gear layout as everyone else, the 5 gear design may only be on the 1283?

[WHITE-TRASH]

Seems like a 1283 gear train in a billet case with something along the lines of hv500 electronics would be pretty damned bomb proof.

[maslin]

Originally Posted by WHITE-TRASH

Seems like a 1283 gear train in a billet case with something along the lines of hv500 electronics would be pretty damned bomb proof.

I would pay a premium for a billet front 1283 case.

[WHITE-TRASH]

Originally Posted by maslin

I would pay a premium for a billet front 1283 case.

I have a friend that is a very talented machinist but he doesn't have time to do one off projects until the winter. I have a 1283 but it's in use. I'll talk to him and see if he's up for it. If he is I'll get that busted top case from you for him to copy.

[maslin]

Originally Posted by WHITE-TRASH

I have a friend that is a very talented machinist but he doesn't have time to do one off projects until the winter. I have a 1283 but it's in use. I'll talk to him and see if he's up for it. If he is I'll get that busted top case from you for him to copy.

Absolutely. Something like that billet Hitec case that's floating around.

Hi Tec 7950 servo cover Summit R/C Products



I have 2 ready to go

[WHITE-TRASH]

One is busted on the left, the other on the right. Just put them together duh.

[Correll]

Those busted metal covers are just aggressive driving, you should slow down and take it easy

Lets go bash at lunch, The AX10 is ready to take that bomber down a peg or two!

[Deckard]

I miss my 1283. The first break wasn't my fault, it was from just normal driving. Replacing the top cover was an easy fix. The second time was due to my half assing the waterproofing. Now I go overboard on waterproofing. I kept the gears just in case I get another one.

A HH with Savox gears??? Shut up and take my money. The HH servos are quiet. Savox sounds a bees nest in my front axle.

[maslin]

[maslin]

Longer video today, back to the Polaroid. Much better video quality, but no sound

The 1283 is doing great, plenty of abuse the past few days. I believe I've tweaked a fancy VP rear axle shaft, the right rear wheel has a decent wobble. As long as it doesn't snap off at the flange I'm happy.

[maslin]

I'll just keep posting, hopefully some one enjoys it

Blew the rear outer pinion bearing yesterday, threw some new bearings in and the housing is worn out Had a spare axle laying around, swapped it over real quick and went back out

[calcagno45]

Looks like a fun spot! did realize how much is edited out the clean version of Still Fly.

Nice back flips at the end