servo help

[Devinb]

I'm putting together a build sheet for an Axial ARTR that I want to get in the near future. I think I've got everything pretty much figured out, except the servo. I plan on running a Tekin FX-R ESC, CC BEC, and 3s 1800mAh 20c lipo battery. What would be a good, strong, reliable servo to match? I've seen people use the Hitec 5955 as well as the 645MG. Would these be good choices? What specs do I look at that make a good servo? Any help would be great.

Thanks-

[PaloAltoK5]

Originally Posted by Devinb

I'm putting together a build sheet for an Axial ARTR that I want to get in the near future. I think I've got everything pretty much figured out, except the servo. I plan on running a Tekin FX-R ESC, CC BEC, and 3s 1800mAh 20c lipo battery. What would be a good, strong, reliable servo to match? I've seen people use the Hitec 5955 as well as the 645MG. Would these be good choices? What specs do I look at that make a good servo? Any help would be great.

Thanks-

for crawlers, it's all about the torque.

Check the list for more info: Hitec Servos

[jamesdicken]

get a titanium gear hitec or tower.something above 300oz/in

[Scattman]

Originally Posted by Devinb

I'm putting together a build sheet for an Axial ARTR that I want to get in the near future. I think I've got everything pretty much figured out, except the servo. I plan on running a Tekin FX-R ESC, CC BEC, and 3s 1800mAh 20c lipo battery. What would be a good, strong, reliable servo to match? I've seen people use the Hitec 5955 as well as the 645MG. Would these be good choices? What specs do I look at that make a good servo? Any help would be great.

Thanks-

There is a huge difference between a 645(140 oz in) and a 7955(new 5955 replacement)(333 oz in)

You need at least 200 oz in but I recommend more.

Basically get as much as you can afford. Best bet would be to get a 7955TG if you can swing it. I just picked one up for less than 100 shipped.

I have run a Hitec 645, a TP946R, a 5955TG and a 7955TG on steering before. I have run the 645 and the 946R on 6.8 volts and were still weak for serious comp use. Might work for small gtg's and bashing but get it in a good enough bind and they won't be enough.

I have even run a 5955TG on 6.8 volts and a couple times wish I had just a little more.

Bottom line is you can never have too much turning power. Keep in mind when you step up to the big servo power, make sure you have your endpoints set up correctly. If not, bye-bye servo.

[Devinb]

Thanks for the help.

The buggy won't see any serious abuse, no comps or anything. It's just a toy to play with.

How do you know what volts to run through them? Is 6.0 pretty standard? I don't want to break/fry anything. I just want a trustworthy crawler that I know won't melt down on me. I don't want to pay ~$25 for the castle link for the BEC when I can order the BEC from Holmes Hobbies with a pre-set voltage for $2.50.

Scattman, where'd you get the 7955TG for less than $100?

[Devinb]

Originally Posted by jamesdicken

get a titanium gear hitec or tower.something above 300oz/in

Tower? The only Tower ones I can find are either micro or cheap, which makes me think they're poor quality.

What other brands should I look at besides hitec?

I found the Futaba S5301. It's $15 cheaper than the Hitec 7955TG but has ~50 less oz/in power. How are the Futabas compared to the Hitecs? Is one a better quality unit than the other? Or is it like Ford vs Chevy?

Thanks-

[O.C.D.]

I ran Futaba all of my RC life (since 89ish) in all of my offroad/onroad vehicles. I have never had a problem other than using the wrong servo for the job. Futaba's are great but tend to be underpowered. I could only find a 333 oz @ 6volts on their site. Hitec tends to have more power on more of their servos it seems. I have the 5955/2*225's/and a 645 (coming). They are all my first Hitecs. With a bec they are great.

[PaloAltoK5]

Originally Posted by Doc J33P

I could only find a 333 oz @ 6volts on their site.

The issue I have with that, is Nylon gears and that much torque is asking for stripped gears in any bind.

What I like about the Hitec's is metal or Ti gears, and the better ones have an overload circiut so even if you do bind it up and overheat it, it will just shut off for a while until it cools down. Much cheaper than replacing the servo because you let the smoke out!!

[newbie8324]

how do you set up the end points on the servos???

[freetimecrawler]

Originally Posted by newbie8324

how do you set up the end points on the servos???

You don't, EPA's (End Point Adjustment) is set on your radio.
And not all radio's have EPA's.

[Timmahh]

I would recommend the JR Z9000T (320 in/oz) Z9100T (370 in/oz) or the DS 8711 (405 in/oz) of torque.

couple that with the JR 3 yr warrenty and the relatively same cost for the Hitec 5955 and its an easy choice.

[Scattman]

Originally Posted by Devinb

Thanks for the help.



Scattman, where'd you get the 7955TG for less than $100?

Here but the introductory sale is over and now they are 114 plus shipping. It was 91 plus shipping 2 weeks ago.:-(

http://servocity.com/html/hs-7955tg_servo.html

[Devinb]

Originally Posted by Timmahh

I would recommend the JR Z9000T (320 in/oz) Z9100T (370 in/oz) or the DS 8711 (405 in/oz) of torque.

couple that with the JR 3 yr warrenty and the relatively same cost for the Hitec 5955 and its an easy choice.

Thanks for the recommendation. I'm not so much concerned about the warranty (Hitec has a 2-year), but the Hitec has titanium gears compared to the JR's metal. How important are the stronger gears? Is it pretty common to strip metal gears with that strong of servo or practically unheard of?

[Devinb]

Originally Posted by PaloAltoK5

What I like about the Hitec's is metal or Ti gears, and the better ones have an overload circiut so even if you do bind it up and overheat it, it will just shut off for a while until it cools down. Much cheaper than replacing the servo because you let the smoke out!!

From what I could find, you need to have Hitec's new programmer to activate the overload protection. Per Obrien Hobbies, "the new HFP-20 programmer is required to activate the new programmable functions of the HS7955 series." Am I reading that right, or does it come pre-set with overload protection?

[Scattman]

Originally Posted by Devinb

From what I could find, you need to have Hitec's new programmer to activate the overload protection. Per Obrien Hobbies, "the new HFP-20 programmer is required to activate the new programmable functions of the HS7955 series." Am I reading that right, or does it come pre-set with overload protection?

You need a programmer. They have a part # for a cheaper programmer that hooks to the computer but it is not available yet.

Can't see spending $130 on the current programmer for a $100 servo..............................yet.

[SDheavymetal]

I heard you can run the hitec 5955TG on 7.2 volts and get 400oz. I saw it when I was researching servos. I running the towerpro from JPcustom 200oz for $18.95 +$3.00 shipping-I got three because my son broke 2 servos on his AX10-I have never broken a servo.(not tring hard enought) I needed something cheap if he broke again. It works good.

[PaloAltoK5]

Originally Posted by Scattman

You need a programmer. They have a part # for a cheaper programmer that hooks to the computer but it is not available yet.

Can't see spending $130 on the current programmer for a $100 servo..............................yet.

HS-7955TG
Hitec's best servo just got better. Based on the powerhouse HS-5955TG servo the HS-7955TG has the added benefit of our G2 second generation programmable digital circuit. This new circuit has twice the resolution of our original circuit while adding programmable overload protection. The HS-7955TG has been designed for the most demanding hobby applications including the largest aircraft and monster trucks. Featuring a titanic 333oz./in. of torque at 6.0 volts, all this power is harnessed by incorporating the industries first Titanium gears for incredible wear resistance and two strong hardened steel gear pins and axial brass bushing in the servo case.

Detailed Specifications

Motor Type:CorelessBearing
Type:Dual Ball Bearing
Speed:0.19 / 0.15 sec @ 60 deg.
English Torque:250 / 333 oz.in (4.8v/6v)
Metric Torque: 18 / 24 kg.cm
Standard Size:1.57" x 0.78" x 1.45" Metric SizeL 40.00 x 20.00 x 37.00mm
Weight:2.29oz65.00g

Detailed Feature Descriptions

G2 Digital Circuit
Coreless Motor
Dual Ball Bearing Supported Output Shaft


Titanium Gear Train (MK first gear) Programable Features Include:

• Dead Band Width
• Direction of Rotation
• Speed of Rotation (slower)
• End Points
• Neutral Points
• Fail Safe On/Off
• Fail Safe Point
• Resolution* (default is high resolution)
• Overload Protection* (default is off)

*these features are only programable with the HFP-20 field programmer

[montereycrawler]

Originally Posted by Devinb

Thanks for the recommendation. I'm not so much concerned about the warranty (Hitec has a 2-year), but the Hitec has titanium gears compared to the JR's metal. How important are the stronger gears? Is it pretty common to strip metal gears with that strong of servo or practically unheard of?

I run both the 5955 and 8711. They are both great but I prefer the JR 8711. I have not had gear problems with either and run them at 6.2v. The 645 on the other hand and Hitec 5645 both are very easy to stip the gears in with a crawler.

[Devinb]

Originally Posted by montereycrawler

I run both the 5955 and 8711. They are both great but I prefer the JR 8711. I have not had gear problems with either and run them at 6.2v. The 645 on the other hand and Hitec 5645 both are very easy to stip the gears in with a crawler.

What about the JR makes it more preferable?

While we're talking about strong servos, am I going to be breaking stock knuckles left and right with a beefy servo (Axial ARTR)? Or can they take a little abuse?

[montereycrawler]

The JR has more power, and seems to respond faster.

Usually people break knuckles and axle c's from tumbles and falling off of ledges and rocks. I doubt you will break one just because of the servo. I would defininitely upgrade to aluminum when you can though.