Linear movement of control rods.

[mylo]

Good damn day,

Is there an optimum distance for the linear motion of a control rod ? In case I'm not saying this right, when moving the rod back and forth to control the forward planes, how far should that rod move when it moves the planes to both it's extremes ? From what I've learned so far, this linear movement can be adjusted by the length of the radial arm from the dive plane axel....shorter arm, less linear motion, longer arm, more linear motion. I'm probably using the wrong terminology, but hopefully my question is clear. Engineering is not my forte'.

I was just wondering if a servo works 'best' when this linear motion is a certain distance, not too long....not too short.

Many, many thanks.

Mylo

[cstranc]

In theory if you have

In theory if you have longer motion any "slop" in the joints will be less significant. Of course it's best to have no play in the joints.

One thing to think about is to ensure you have nice linear motion. If you use a direct connect to the servo horm it generates longtitudinal and horizontal motion. The horizontal motoion might cause issues at the seal of the WTC.

No expert but I think the movement you have on the servo needs to match the movement on the control arm for the dive plane / rudder etc.

I once increased the length of the servo arm and it caused binding in the linkages. But that could have been because I was using brass cable in a tube instead of 1/8" rods as the linkage. Or maybe my control arms were too short.

I am guessing that longer motion will be smoother, but you will bump into issues with space for the corresponding control arms. Especially if your rudder & dive planes are in a confined space. Of course with the size of your boat maybe there is no confined spaces. You can probably get lost inside your model.

[mike dory]

Servo motion

Mylo - This is just a thought, You might give rotary motion A thought.(going through the top of your WTC) This type of motion has less drag then Linear motion through an O-ring, It's not as easy to set up but once it is, your O-rings will last e great deal longer and with less no binding then with Linear... I've used this in all most, all my boats it works well. This is just a thought. .. Best wishes... Mike Dory

[mylo]

Chris,

Believe it or not,

Chris,

Believe it or not, I'm dealing often with what I feel are confined spaces at the extreme bow/stern.......just can't squeeze my hands in there. How guys build small boats (anything less than 6' long), ...I have NO idea, my hat is off to them.

Mike,

I have given rotary motion lots of thought, but short of having to engineer some sort of gear set to convert rotary into linear motion, I don't see how it's done. I don't want the added expense/complication of any kind of gear set. I understand exactly what you are saying about linear motion and how it relates to WTC seals, but I was thinking that if I used one of those.....whatever they are called.....'accordian boots' instead of a linear seal, that would work well, reducing the required maintenance/replacement of the seal. Have you got any schematics/diagrams showing this rotary motion to linear motion concept ? ....I'm a 'picture' guy, especially when it comes to mechanical engineering.

Thanks much,

Mylo

[JWLaRue]

Mylo,

.....this might be what you

Mylo,

.....this might be what you are asking about.....?

http://s181686668.onlinehome.us/phpBB2/viewtopic.php5?t=7168

-Jeff

[mylo]

Jeff,

Yes, those 'bellows' (bellows....accordian

Jeff,

Yes, those 'bellows' (bellows....accordian boots, ....what's in a name) are exactly what I'm talking about. I see no reason why they wouldn't work well and as you point out, allow 'less than perfect' alignment of the control rod through the WTC. I'm guessing that the resistance caused by the bellows expanding and contracting is insignificant ?

They look like the same things on motorcycle handle bars to keep the clutch and front brake cables protected.

Mylo

[JWLaRue]

Mylo,

Correct, the bellows offer very

Mylo,

Correct, the bellows offer very little resistance to the motion of the linkage. I got those from OTW, but these can be had at most automotive supply stores. They're vacuum line fittings.

-Jeff

[Guest]

The bellows that Robbe supply

The bellows that Robbe supply for their range of model subamrines are really nice- they concertina very well indeed.

Pandan sell them-

http://www.pandanmodelboats.co.uk/acata ... llows.html

Also you may want to check out linear servo conversion kits, they're very good!

http://e-clec-tech.com/lisekits.html

Andy

[scott t]

http://www.geocities.com/smallworldmodels/ss581/srvoinstal3.jpg
Small world model WTC servo


Small world model WTC servo holder.

Servo rotates a shaft.
Control horn is outside WTC.

http://www.geocities.com/smallworldmodels/wtc.html

-Scott

[wlambing]

Scott and All,

SWM is

Scott and All,

SWM is making anything last I heard. Dave hadn't got his shop up and he was saying he was only going to work on a Sierra kit, nothing else, when he got his shop done. That was months ago. I'm sad, as we all should be, 'cos he made good stuff and had reasonable prices to boot!!!!!!!!

B^(