Crawler setup (electronics)

[JimBear]

I am in need of a few examples of a working system (esc, motor and servo) combo for a trail truck. I am having all sorts of issues with the stuff I have on hand, so I need a baseline to work from.

Am I correct in assuming that it needs lipo, and that NiMH is too underpowered to be able to drive 25 kg servos?

What electronics do you use in your crawler?

[Mad Ax]

Short version: Hobbywing 1080, cheap 25Kg servo, cheap 55 turn sealed can or rebuildable 5-pole motor depending on budget, 3S LiPo for extra speed between courses.

Long version:

ESC: Hobbywing 1080.  I won't run anything else in my crawlers.  (OK, I have run other stuff either because it's come bunded in the package or I was in a pinch and didn't have time to get a 1080, but it never feels the same).

The new V2 1080 has some extra features that I've only just started using (literally just around my workshop, I haven't used them on the trails yet) - I'll come onto those later.

Servo: generally a Power HD 25Kg from Amazon, but I've also used other cheap high-torque servos, even down to around 10Kg, in the trucks with smaller wheels.  Those 25Kg servos really come in when you're using Class 2 or bigger wheels in really tight rocky courses, if you're just trailing you don't need a high-torque servo.  That said, there's not much price difference between the two.  Be aware that some "metal gear" servos have brass gears, if you're going hardcore then you'll want steel - if the splined shaft is a goldie lookin' colour then it might not be as tough as you think it is.

Motor: 55 turn brushed is my default.  I also have a couple of 5-pole motors (I think a 16 turn and 21 turn?)  - I still haven't got my head around how the turn counts correspond to conventional motors.  The 5-poles are indeed very smooth and feel nice on the trails, and if you're going for the mod-motor price bracket, it might as well be a 5-pole.  However there are some perfectly good sealed 55-turn motors in the bargain-basement price bracket.  I've ruined a couple of these when they've got wet and rusted up, but at that price it's not a huge loss.

Battery: 3S LiPo all the way for me, the bigger the better.  Some of my crawler events have 100-gate courses, being able to do a couple of courses in the morning then change the battery during the lunch break is a mega bonus, especially if the weather's bad.  3S gives you plenty more power in that 55-turn motor and a good deal more speed without compromising the low-speed gearing.  Being able to almost keep up with my friends with their 2-speed TRX-4s between trail sections, but still have the torque for the tough climbs, was a game-changer.  I never run 2S in my crawlers now, everything is geared for 3S.

Then there's the setup.  I tend to run 100% drag brake on my technical crawlers, but less on my trail rigs, as them coming to a dead stop in front of me while I'm walking is a problem.  Also 100% can make them topple over if not handled correctly.

I also run an instant forward/reverse config without the brake option - I don't need it with 100% drag brake.  That makes it very simple to manoeuvre without worrying about whether I'm reversing or braking.

BEC - 7.4V for me.  I've only ever burned out one servo and that was because the gears slipped and it got stuck past its endstop.  Also makes a big difference if you fit a servo winch (which I consider to be 100% essential in a crawler).

Radio - personal preference I know, but while I use wheels for racing, I always use sticks for crawlers.  The additional analogue channels are great for special functions (e.g. winches) and the switches tend to be easily accessible too.  Plus it just feels right to me.

If you just want to go trailing then you don't need additional channels, but they can be useful - for example I have my winch (right up/down stick) toggled by a 2-way switch, so when I'm driving normally the winch won't operate, but when I flip the toggle switch the winch becomes active using the right stick.  This is set up using the DR feature on my FlySky i6.

Also I can set up another toggle switch for throttle hold - then I can dial in a basic walking-pace throttle setting, which is nice for general trailing and means I don't have to hold the transmitter all the time, I can just flip the switch and let the transmitter hang.

Also I can set up another toggle switch to completely disable the throttle - that's useful if I have to do repairs or set up the winch line, as it stops the truck from moving off while I'm scrabbling around in the dirt with the transmitter hanging off my neck.

Finally - on the 1080v2 - it has 2 cool new features, adjustable drag brake and real-car reverse mode!

Adjustable drag brake: plug one of the floating wires into a spare channel on your receiver, and you can adjust how much drag brake you get by turning a knob.  I haven't used this on a course yet but I expect it will be a bona fide game changer.

Real-car reverse: plug the other floating wire into a spare channel, and you can toggle reverse using a 2-way switch.  That way, up-stick always means "go" (either forwards or backwards) and back-stick always means "stop" - but never "move".  This is how I set up my big rigs and my hillwalking truck, so it's natural for me to drive like this, and (along with the adjustable drag brake) gives you way more braking control in descents.  A total game-changer, and given the new model is the same price as the old one, it's a no-brainer.

 

[JimBear]

Very thorough and helpful, @Mad Ax! Maybe I'll just switch to some other radio and see if I can get one of the servos to play nicely. I already have the 1080v2, but it needs some setup work.

[Frog Jumper]

I have a Holmes motor in my cc02.  It was dirt cheap but works very well.  

[JimBear]

Some further observations on @Mad Ax post:

Servos: I have to try the Power HD servos - the ones I have are truly no-name, cheap (15 euros a piece) things. They've made 4ws into a bit of a bother, since they center on whatever they feel like.

Motor: 55T sounds really ... ahm... slow, but reading further on, I guess coupled with the 3s batteries, it works better than expected in the speed department. I took delivery of a RC4WD 45 T today, no idea if it is any good. I have a CR tuned 35 T that works fine on NiMH.

Batteries: I will have to get down to lipos, I'll start with 2s and see how that works. Especially with the 45 T.

The setup will have to wait - I need to put things in working order first. But a bunch of interesting things in there, for sure.

BEC - this one I am trying to get my head around that- what to get and how to intall.

Radio - I learnt on a stick radio, and wheel works, but given the choice, I think I am more of a stick man. Not sure if a Flysky i-6X or a Futaba T6L. It's a bit hard to figure out since anything above a 4 channel stick radio seems to geared towards airplanes. I don't know if they work or can be made to work?

[Losi XXT-CR]

I use a Flysky FS-i6 stick radio on a lot of my RC cars. My only crawler is a somewhat modified 6wd Dynahead: https://www.tamiyaclub.com/forum/index.php?/discover/content-started/#:~:text=Dynahead 6wd non scale crawler build thread....with a twist!

I'm using a stock 27T silvercan at the moment and a 1080 ESC. Which works really well IMO. I did get the programming card with it and tweak the settings a bit. I'm also running the cheap 25kg servo's (2 of them for 4 wheel steering).

I only run 2S LiPo, but can't see that I'd ever need more to be honest.

[JimBear]

21 hours ago, Losi XXT-CR said:

I use a Flysky FS-i6 stick radio on a lot of my RC cars.

Is it this one? - looks like something that fits the Dynahead in that case.

 

[Losi XXT-CR]

1 hour ago, JimBear said:

Is it this one? - looks like something that fits the Dynahead in that case.

 

Doesn't quite look like that, but might be similar.

This is it:

It is designed for airplanes. So the throttle is ratcheted as stock. I bought a spring kit to convert it to a normal stick. I went with this one because it was fairly cheap to buy and has (had) easily attainable and affordable receivers. I've also got a Core RC stick Tx, but supply of the Rx's vanished, which was annoying. I currently have 10 models on the FS-i6 and 3, maybe 4 more Rx's in the draw still. It is fully programmable, such as throttle curve, dual rates, end-points, etc. The extra channels are handy, on my Konghead I have the rear wheel steer activation on a toggle switch and then used the left stick, the throttle one to steer by going left and right with it, leaving the right stick free for the front steering.

Note mine should have a 4th toggle switch to the right of the dials, but I had an accident last week with it and broke the switch, so it has a temporary bodge repair currently. 

[JimBear]

Great to know! - if I get something like this, I'll have to reconfigure it too. Would this spring conversion kit be something like "self centering throttle mode (1 or 2)"?

[Losi XXT-CR]

6 minutes ago, JimBear said:

Great to know! - if I get something like this, I'll have to reconfigure it too. Would this spring conversion kit be something like "self centering throttle mode (1 or 2)"?

You'd need something like this: https://www.aliexpress.com/item/1005003931026404.html?src=google

You do have to open the Tx up, but it is fairly easy. There are YouTube vids on how to install it.

Don't know if you have flown RC planes/Heli's etc. But most (Mode 2) have the left hand stick as the throttle, so it stays where you put it, rather than returning to the centre. This mod adds a spring to self centre.

[Mad Ax]

On 10/12/2024 at 5:32 PM, JimBear said:

Servos: I have to try the Power HD servos - the ones I have are truly no-name, cheap (15 euros a piece) things. They've made 4ws into a bit of a bother, since they center on whatever they feel like.

Can be an issue with cheaper servos but I find it less a bother with crawlers since I'm on the steering so much anyway (unlike say a race car where it must remain straight and true down the back straight).

On 10/12/2024 at 5:32 PM, JimBear said:

Motor: 55T sounds really ... ahm... slow

it is, especially on 2S, but that's sort of the point of a crawler.  On 3S most of my crawlers will go faster than a brisk walking pace, but the slow motor speed helps with climbing tricky technical obstacles.  I guess it depends what you want out of your crawler - if you want more of a trail rig then a lower-turn motor or higher gearing would be of more benefit  

On 10/12/2024 at 5:32 PM, JimBear said:

BEC - this one I am trying to get my head around that- what to get and how to intall.

The 1080 already has a built-in BEC, so unless you're adding loads of electrickery, you won't need an additional one.  In the setup of the 1080 you can select from 6V (which I believe is about normal) to 7.4V.  I think the 1080v2 can go even higher.  This assumes you're running 3S - my experience with the 1080 on 2S is the 7.4V BEC mode only puts out around 7v.  Most servos are only rated to 7v but in my experience they run just fine on 7.4V, as do the FlySky receivers - I've never burned one out running 7.4V.

I've got rigs that have full LEDs, two winches and a hi-torque servo and have never needed an additional BEC - the 1080 is plenty.

On 10/12/2024 at 5:32 PM, JimBear said:

Radio - I learnt on a stick radio, and wheel works, but given the choice, I think I am more of a stick man. Not sure if a Flysky i-6X or a Futaba T6L. It's a bit hard to figure out since anything above a 4 channel stick radio seems to geared towards airplanes. I don't know if they work or can be made to work?

I use an FS-i6X (previously an FS-i6).  The roundy-shape FS-i6S that you posted is pretty much the same transmitter in a modern-style case, but I like the oldskool transmitter look better.  As long as you fit the throttle return spring (mentioned above) it will be fine - yes, it's made for aircraft, but you can repurpose a lot of the aircraft-specific stuff for crawler things.

[Busdriver]

Another route you could try is the Hobbywing fusion’s. Two quality levels and two power levels in each. Cuts out the need for separate esc and gives you sensored brushless control. Relatively inexpensive especially from AliExpress.?

easy to program and give amazing modulation and often greater speed. I think they are also waterproof ( or at least I hope they are as I already have 3x540 size and 1x mini 16) 

[JimBear]

As for the 1080 - thanks for the tip on the BEC and the possible 7.4v - I may have set it up at 6v, but I will have a look at it again.

The higher-turn motors - weil, it's crawling. I am aiming for slow walking pace rather than anything. I'll have to experiment, as Dr Frankenstein said.

5 hours ago, Mad Ax said:

I use an FS-i6X (previously an FS-i6).  The roundy-shape FS-i6S that you posted is pretty much the same transmitter in a modern-style case, but I like the oldskool transmitter look better. 

I prefer the older look too. And being a dinosaur, I like the tactile experience. I looked around and was able to find them for about 55 euros. I might give that a go. I found an older video with an excellent tutorial on how to change out the lever/spring. Looked pretty fiddly but doable.

[JimBear]

4 hours ago, Busdriver said:

Another route you could try is the Hobbywing fusion’s. Two quality levels and two power levels in each. Cuts out the need for separate esc and gives you sensored brushless control.

I may have a look at that in the future - I like the idea. Noted.

[MadAnt]

I don't know if I could recommend the complete correct way to go for the electronics, because my setups are all over the place depending on the vehicle. 

I can say is use a good metal gear high torque steering servo, but don't go overkill or underpowered.

8-11 Kg-cm servo for a light CC01 is plenty in most cases, but 25 kg is overkill.

Class 1 crawlers may require more than 10 kg depending on vehicle weight.

25 kg or higher servo for a class 2 or 3 crawler is good in most cases, 11 kg is the minimum but 8 kg is not enough.

Some setups can draw so much power that they overload the built in BEC and everything shuts down for a little bit. This is called a brown out, an external BEC is usually what is needed to cure this issue.

Some of the things I have stated may be a close to what others say as well, but it works.

As for the rest of the setup and whatnot, it's more of personal preference. 55 turn crawler motors and crawler esc's may be the norm and most recommended, I sometimes do things a bit differently.