Assembling the Merriman 2.5" Standard WTC

[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]

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,

[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?

[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 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]

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

[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]

correcting a color cast in the photos

I really don't know if anyone cares about this but I do so here goes. You may have noticed that I try and include a piece of white in most of my photos. That's not accidental. I do it to allow me to correct the green color cast caused by the fluorescent lights over my work station. I'm using Adobe Photoshop Elements 4. It's in the Enhanced menu under Color.

Here's the before...... and here's the color corrected version...

This is undoubtedly more important in nature and people photos but what the hell...

Dan

[roedj]

Preparing the on-board bottle cylinder hole

With some behind the scenes advice from DM I've decided to enlarge the cylinder hole where the on-board bottle is placed.

First I sanded and filed the hole......the hole now looks oblong like this...... God, I hate the effects of digital photography. Every little scratch and oops really shows up.

"What did you use to make the hole bigger, klutz, a jackhammer?"

Anyway, I did it to allow me to turn the bottle inside the cylinder for the ballast tank assembly like this......then this...,,, and finally this......

I also had to deepen the "O" ring channel just a tad to allow me to actually get the bulkhead in the cylinder, like this...... be sure to use a nice sharp rat tail file and go slowly as a little filing goes a long way when you're only trying to remove a fraction of a millimeter.

Dan

[roedj]

bulkhead tool + velcro

I've decide to use Velcro brand products to attach the various components to the equipment frame on the motor bulkhead ...... more on this later.

I've purchased the purest silicone grease I can find to lubricate the "O" rings......It's available in a lot of SCUBA dive shops.

The assembly procedure for the SD ballast tank has at least one "tricky" part which, hopefully, won't be so "tricky" in the end. It's the part where we attach the gas line to the gas bottle. I'm sure DM has worked this out long ago but I see only one way to do it. The problem is that I cannot turn the gas bottle inside the cylinder......it's just too bloody long. This means, I think, that the gas line must be attached externally to the cylinder and the only way to do this is to physically bring the gas line outside of the cylinder like this......I had to push the bulkhead forward of its normal position to get enough of the gas line outside of the cylinder. I also did not push the bulkhead so far forward that the "O" ring would be over the ballast tank hole for fear of nicking the ring. Note that for this demo I did not have the hose compression collar on the tube nor did I have the "O" ring installed on the bulkhead.

I've made up a tool...... to move the bulkheads around inside the cylinder. It's two pieces of 1/2" by 3/8" basswood glued to a piece of 1" by 3" milled pine. It just fits in the cylinder. With this tool I can push the bulkheads in and out of the cylinder...... because the tool is longer than the cylinder...... It can get around the gas bottle if need to be adjust a bulkhead....

Later, I'll show the actual assembly of the ballast tank.

Dan

[roedj]

Greasing the "O" rings

The conduit tube is greased, not RTV'ed when slipped into the ballast tank space.
David,

What kind of grease do you use? Can I use this same grease to apply to the "O" rings to make it easier to slide the two ballast bulkheads into the cylinder?

The strain-relief block glues to the inside face of the forward bulkhead and is drilled to pass the three wires between battery pack plug and mission switch -- it unloads the switch solder joints from any flexing as a consequence of battery handling.

Also, I see where Caswell sells a waterproof switch, P/N BHWS, which is rated for 250V @ 2 amps. Do you recommend this switch to be used to turn the system on and off? I'm a little concerned because I think the current draw could be occasionally as much as 5 amps or more with all the electronics and the motor sucking current. I see a depression molded into the dry side of the forward end cap. Is this where you would install the switch? I'll also glue the strain relief block nearby too.

David,

I've made up a wooden tool to aid in the installation process. I'll show a picture later.

Dan

[roedj]

Dan,

The strain-relief block glues to the inside face of the forward bulkhead and is drilled to pass the three wires between battery pack plug and mission switch -- it unloads the switch solder joints from any flexing as a consequence of battery handling.

David,

David,

Which three wires? I can see switching one of the battery leads (+ or -) to effect an on/off condition but I don't get the three wires comment. Please explain.

BTW, good to have you back. I take it your presence here means thing are improving on the home front.

Dan

[He Who Shall Not Be Named]

Someone,

Can someone confirm for me that this round black "thing" in the hole in the ballast tank bulkhead is, in fact, an "O" ring?...[ATTACH=CONFIG]4352[/ATTACH] It sure looks like one to me but who knows?

I'm asking because I'm wondering if I need to use some sort of RTV sealant for the brass interconnecting tube or can I just rely on the "O" rings to keep the water out.

Dan

Dan,

Yes, both ballast bulkheads have this O-ring which effects the seal between bulkhead and conduit tube. The conduit tube is greased, not RTV'ed when slipped into the ballast tank space. It's the last item to 'slip' into place during assembly.

The strain-relief block glues to the inside face of the forward bulkhead and is drilled to pass the three wires between battery pack plug and mission switch -- it unloads the switch solder joints from any flexing as a consequence of battery handling.

David,

[He Who Shall Not Be Named]

See the web page for Mtroniks

Look for the Micro or the Nano. Same thing, except the Nano has no epoxy or wires, making it smaller.

Nooooo! ...

The Nano is only for the boats witha 1.25" SD!

David,

[roedj]

Now I'm distessed bait

Someone,

Can someone confirm for me that this round black "thing" in the hole in the ballast tank bulkhead is, in fact, an "O" ring?... It sure looks like one to me but who knows?

I'm asking because I'm wondering if I need to use some sort of RTV sealant for the brass interconnecting tube or can I just rely on the "O" rings to keep the water out.

Dan