Backlash build

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Kevinfipps

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Jan 2, 2016
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36
Need some photos and info on radio box and linkage set up first backlash gas hydro build
 

rhomodel

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Jul 15, 2003
Messages
293
Did Bob not provide these with the kit?
Alternative search for Backlash on the forums: plenty of pictures..
 
Last edited:

RichJones

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Joined
Jan 6, 2016
Messages
184
The instructions don’t really get into linkages and such. There are some materials recommended but that’s about it. Everyone has their own way of going about these so I would imagine there’s just no one perfect way of doing it. I can show you what works for me. The throttle is a cable setup rather than fussing with a bell crank rig and I have to tell you it works really really well. The cable kit is available from Zippkits. I got the longer one and cut to size. The throttle servo is a Futaba SBus servo. I have a 7PXR radio so I bought a couple of these to play around with. Any servo with 40-50 oz of torque should do the trick. The steering servo is obviously a Savox. It’s the 1210 SG I believe. It gives you around 270 oz in at 6.0 volts and that is more than enough. You could get by with less but I wouldn’t go less than 175 oz in or so. On the steering linkage, I used 4-40 ball links. I like the bolt through setup. The rod is a carbon arrow shaft ( I bought a set on Amazon for like 20.00 so I have pushrods material for a long time) and the ends are 1/4 nylon bolts. The bolts are drilled through for the 4-40 pushrod ends. You’ll see I drilled a hole in the carbon rods a few inches in and put a 90 deg bend in the 4-40 rod and cut the rest off. This gets pushed into the rod and engages with the hole. The nylon bolt pushes or twists into the rod with some epoxy. When the epoxy dries everything is solid and ready to install. There is a video from Scott Meyers on YouTube that describes the process well. He machined metal ends. The nylon works fine but to each his own. I hope this helps!

Rich

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Kevinfipps

Active Member
Joined
Jan 2, 2016
Messages
36
I seen something with this boat in it it was photos from start to finish on the build and now I can’t find it
 

RichJones

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Joined
Jan 6, 2016
Messages
184
If you google Blazer Backlash Build there is an article that Randy Rapedius did on Modelgasboats.com that’s good. Also on Jim’s RC Boat Dock, if you search Blazer Backlash in the builders forum, there’s a lot of good stuff there. And there’s plenty of stuff here too. The pdf instructions from the blazer marine website are pretty straight forward with pics too. After all that if you get stuck, ask someone here or on Jim’s RCBD.
 

Wasted wages

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Joined
Jan 2, 2006
Messages
1,288
Those arrow shafts are pretty trick!
Nice job on making up the 4-40 ends, simple secure and just plain works !

None of my boats have rods that long, that would benefit from these, but always good to learn new building skills.

I typically take my 4-40 rudder pushrods, buff them off with a green scrub, cover with paste flux and slip a tight fitting brass tube over the rod. Then hit it with a torch and work 95-5 solder inside the tube from one end to the other.
I've never had one bend. Something else will break first.

I still believe all electronics belong in the radio box, but one day I may try putting watertight servos in the hull to cut down on pushrod length.. I like the idea of this, but I just don't want to have to replace corroded and soggy servos on a regular basis..
 

Wasted wages

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Jan 2, 2006
Messages
1,288
Rich,
I forget to ask, on that cable type throttle setup, does the aluminum disk attached to the servo come with the cable kit ? Or is did you machine it yourself ?

@RichJones
 

RichJones

Well-Known Member
Joined
Jan 6, 2016
Messages
184
Those arrow shafts are pretty trick!
Nice job on making up the 4-40 ends, simple secure and just plain works !

None of my boats have rods that long, that would benefit from these, but always good to learn new building skills.

I typically take my 4-40 rudder pushrods, buff them off with a green scrub, cover with paste flux and slip a tight fitting brass tube over the rod. Then hit it with a torch and work 95-5 solder inside the tube from one end to the other.
I've never had one bend. Something else will break first.

I still believe all electronics belong in the radio box, but one day I may try putting watertight servos in the hull to cut down on pushrod length.. I like the idea of this, but I just don't want to have to replace corroded and soggy servos on a regular basis..
Thanks yeah it works just fine. To be honest a 4-40 rod by itself would probably work in my application, or 2 rods wheel collared together in the middle. But I saw others doing these and thought I’d give it a try. I like your idea too!
 

RichJones

Well-Known Member
Joined
Jan 6, 2016
Messages
184
Rich,
I forget to ask, on that cable type throttle setup, does the aluminum disk attached to the servo come with the cable kit ? Or is did you machine it yourself ?

@RichJones
The aluminum disk comes with the kit. I think you can buy the parts individually too.
 

RichJones

Well-Known Member
Joined
Jan 6, 2016
Messages
184
Those arrow shafts are pretty trick!
Nice job on making up the 4-40 ends, simple secure and just plain works !

None of my boats have rods that long, that would benefit from these, but always good to learn new building skills.

I typically take my 4-40 rudder pushrods, buff them off with a green scrub, cover with paste flux and slip a tight fitting brass tube over the rod. Then hit it with a torch and work 95-5 solder inside the tube from one end to the other.
I've never had one bend. Something else will break first.

I still believe all electronics belong in the radio box, but one day I may try putting watertight servos in the hull to cut down on pushrod length.. I like the idea of this, but I just don't want to have to replace corroded and soggy servos on a regular basis..
Oh on the 1/8 Scale and SPORT 40 I’m working on, , I’m using the mini waterproof servos from Savox for third channel and throttle. I’m going to mount the third channel servos outside the box and run the cable through a a tube and through grommet in the box. I will use heat shrink at the point it passes through the grommet to make sure it’s a tight seal. It’ll be my first “naked” servo experiment!
 

Wasted wages

Well-Known Member
Joined
Jan 2, 2006
Messages
1,288
Have you seen the throttle servo setup that mounts to the gas motor itself ?
That's pretty trick too, if I ever do a naked servo, that's probably the route I will go.
 

RichJones

Well-Known Member
Joined
Jan 6, 2016
Messages
184
Have you seen the throttle servo setup that mounts to the gas motor itself ?
That's pretty trick too, if I ever do a naked servo, that's probably the route I will go.
I’ve seen a glimpse or two of it. Enough to know it exists. Definitely worth looking into.
 

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