Assembling the Merriman 2.5" Standard WTC

[He Who Shall Not Be Named]

Dan,

In the absence of good instructions you've done a wonderful job of improvising and coming up with rational solutions to your SD assembly problems. Well done. And your tip on color correction is welcome and appreciated.

Good stuff.

David,

[roedj]

3/16" push rods

To All,

With the Carmel Sub Regatta and some family issues behind me I'm now going to complete this build. But first a question.

I see where the 2.5" WTC uses 1/16" push rods and seals which is just fine and I'm sure work very well. The problem is -- is that I'm a nut job who firmly believes that any assembly like a WTC must be able to completely field stripped down to its integral parts for maintenance or modifications without the use of a soldering iron or wire snips. Please don't waste your time trying to convince me otherwise for, as I said, I'm a complete nutter.

The reason I like 3/16" push rods and their seals is that I can install a 2-56 threaded rod inside of the 3/16" brass tube and thus be able to unscrew anything I may have attached there which allows me to completely remove the push rod from the seal.

I can't see how to do that with a 1/16" push rod system. Does anyone have any ideas on how I might do this?

If I can't come up with a solution to the 1/16" push rod problem I may just drill out or push out the 1/16" seals in the motor bulkhead and replace them with 3/16" seals. I know that will undoubtedly bring down the wrath of "You Know Who" on my head. Oh well.

Now, where did I put my asbestos skivvies?

Dan

[Kazzer]

I imagine His Eminence will say that the larger seals will cause more drag and make your servos work harder. I seem to remember him beating on me about this once, as 'skinny rods' were poo poo'd by another supplier when I mentioned these to him. I passed these thoughts on and started The Wiz ranting 'n raving - again! Mind you, the supplier was selling great big GRP models that weighed a ton, and had not much experience in plastic kits.

Good luck pal!

[roedj]

I imagine His Eminence will say that the larger seals will cause more drag and make your servos work harder.

Mike,

All of which you say is correct. The idea of a 1/16" push rod makes very good sense except when, as noted in my original post, you have a whack job like me who wants to be able to field strip everything. If someone can show me how to do that with a 1/16" push rod system I'll gladly stay with the smaller push rod.

Scanning the sky for cruise missiles - CIWS at the ready,

Dan

[Kazzer]

I'm surprised you are quoting 3/16" push rods. Sounds more like a prop shaft! :-)
Why don't you use the 1/8" seal?

[He Who Shall Not Be Named]

Dear Nut Job,

If you simply have to you can push the 1/16 pushrod seal bodies out of the motor bulkhead with a little force -- they are secured with RTV silicon adhesive.

This is what you do if you get a leaker -- note that in the package of spares there is an extra seal ... just in case, Dan.

David,

[roedj]

I'm surprised you are quoting 3/16" push rods. Sounds more like a prop shaft! :-)
Why don't you use the 1/8" seal?

Mike,

You're spot on ol' sock. I know what I'm talking about even when I say it all wrong (Huh?).

I meant 1/8" push rods - this was just a test to see if you were paying attention - you passed with flying colors.

"He who must be obeyed" has told me how to push out the smaller seal - thanks for that. I shall now proceed to wreck his wonderful design.

Dan

[He Who Shall Not Be Named]

I buy 'em books, I wipe their nose, I drop them off at school. What do they do? ... they eat the frig'n teacher!

**sigh**

David,

[roedj]

they eat the frig'n teacher!
**sigh**
David,

Not gonna happen, I'm on a strict low fat diet.

Dan

[roedj]

the connecting tube

I shall now prepare the connecting tube. This tube is normally used to carry battery, plus and minus, back to the "engine room". However, I shall also use it for one of two possible functions. One, to carry a servo signal back to the forward compartment if I ever decide to place a servo up front - OR - two, use an extra battery up front to just power the receiver, i.e, don't use the BEC of the ESC (don't you just love abbreviations).

First of all I jam the two wired through the tube......then I solder a Deans like plug onto the forward end. I like Deans plugs but I don't like trying to solder to them. So I drill two small holes in the lugs so that I can better mechanically attach the wires to the lug... At this point some of you are shaking your head saying to yourself,"The fool will get into trouble running the servo wire next to the power wire." Well, maybe. I've done this in other circumstances (surface craft) and have never had any difficulty. Maybe I've just been damn lucky. I know the risks involved - let the recriminations begin.

Next I solder the wires onto the lugs using shrink wrap for insulation and strain relief......and ...

If I use a separate battery to power the receiver I must isolate the "battery plus" lead between the ESC and the receiver. For that purpose I have constructed a servo adapter connector without the "battery plus" wire, the red one...

More later,

Dan

[roedj]

assembling the SNORT pump with MPC

As I shall be using a SNORT system with this WTC, I'll now assemble the SNORT with a KMC Mini Pump Controller, MPC.

A picture of a completed one and an unassembled one...

First a drop of solder flux on the case to make soldering easier...
Secondly, put some solder on the case...

Then solder on the wire...

Next, wrap the servo and battery leads with electrical tape to the pump case. This does two things, a) provides strain relief for the wires and b) holds the MPC onto the pump case while you're working on it...

Then solder the grounding wire to the pad on the printed wiring board (PWB)...

Finish up by soldering the pump leads to the MPC and trim off any excess wire...

I did all this using the old "rubber bands around the pliers handle as a poor man's "third hand" trick...

Finally, attach the power plug of your choice and you're good to go (See the first pic).

Dan

[roedj]

Antenna leads

Now it's time to start the assembly of the "engine room". First I prepare the antenna lead. As I'm always after ease of service in the field I shall prepare a rapid disconnect for the antenna lead. I'll use Märklin (German manufacturer of model railroad equipment) banana plugs. I've used these for years in model railroads with no failures. I prepare a star washer by bending it 90 degrees and soldering a wire to it...

Next, using the banana plugs I complete the circuit...

More later,

Dan

[roedj]

The "Engine Room"

This is just the start of this assembly. I spent some time trying to figure out where to place everything. There's not a whole lot of room in this WTC but with smaller components I think it'll all fit (I hope).

Here are three views of what I've done so far......... and ...

More later,

Dan

[He Who Shall Not Be Named]

Hey, Dan:

Put the LPB on the bottom and the receiver on the top. When you take on water in that space, which item you want to keep in the dry?

David,

[roedj]

David,

Ok, I see the logic in that..

BUT...

I thought that the two holes in the transverse shield were made for the leads coming out of the LPB. If I put the LPB on the bottom then I have to run the hoses from the front bottom of the equipment rack up the sides to the SNORT tubes on the back top. The way I have it now it's a straight shot from the LPB to the SNORT manifold on the back seal...

OR...

I have this whole thing completely screwed up.

To get the receiver off of the bottom I suppose I could mount it in the middle area of the front in between where I have the LPB and the receiver now.

Confused in Canton

P.S. What is all this bilge about "taking on water"? Are you saying the designer occasionally makes a mistake (or is just the FUBAR assembler)?