1/72 688 class

[He Who Shall Not Be Named]

I must have the worst timing with phone calls... will have to try again. Land chores to do today, but possibly not all day. But that depends on what does or dosen't break while working...

I'm knee deep in production work today, but can give you a few hours in the late afternoon.

David

[a1965l]

Thanks David. Hopefully I won't need more than a few minutes, but you never know... I will call before I leave

[He Who Shall Not Be Named]

Thanks David. Hopefully I won't need more than a few minutes, but you never know... I will call before I leave

Very good.

[a1965l]

Once again I am in debt to David for his time and efforts. He turned my dual output cylinder into a single:



And steered me onto the right path vis-a-vis mounting the stern planes. He fabbed up 2 yokes in short order...


Which fit very snugly in the hull... but snug is good..



But.. I was still wondering how to get the yoke installed with the planes on.. turns out the answer is a setscrew and some flat spots in the rod. Easy enough, but first I need to glue the broken off plane back on. A few minutes work with the sand block got me a nice flat surface on both the plane and the hull. I threaded the rod through everything, which lined up the plane nicely. A bit of thick CA and just like new...



Still need to so some clearance work, as the movable portions are still kinda tight. Well, at least one is.

David also hooked me up with some material to make brackets to hold the sail on and some other hardware that I need. Of course, I did forget the vertical snort...

[a1965l]

Little more work tonight installing the planes and rudders. Let me preface by stating that I know set screws are the preferred method of attaching yokes, and I intend to utilize them on the permanent install, but the cap head screw were used for conveinence, given that the assembly is going to have to come apart a few more times.
Well.. no 4-40 tap so off to madhouse Lowes to pick one up. My intention was to drill and tap holes in the planes for setscrews to hold them to the shaft. I did a little thinking and decided to drill the holes off 90 degrees, in an attempt to get more meat for the threads, and so that the set screw would clear the fixed portion of the plane when the moveable portion deflected. So...




Easy enough.. threads! I drilled all the way through so I would be certain to get the threads all the way through the hole. Not much material there for tightening down against.





Done! All ready for install!.. well, not quite. There is still some binding with one of the planes, so some work with the old sandpaper should clear it up, right?

Well, more on that later.

Ground some flats on the shaft




and put it all together...





Almost looks like I know what I'm doing. but that's only b/c the yoke is so highly professional. It shines a good light on everything else. Yes that horn is perpendicular to the planes.

Then, realized that I would have to cut the shaft and had no way to index it when I install it. I'll figure something out.. but what the hell let's put it all together anyway..


There are still some interference issues that will be resolved with sandpaper. The rudders are very, very loose.. almost rattly. I may have to re-install the brass bushings in the hull, actually I'll probablly just cut them very short and install them on the rudder shafts. That would be a good way to space the rudders off the hull. that or some nylon washers. I have somewhat the same issue with the fairwater planes, I need some kind of washer to center the yoke in the sail, and don't need the planes rubbing teh sail to do it.

Money shot...



Still need to trim the ends of the shafts and obviously orient the yokes in the right direction. As I mentioned before, one of the planes still has some interference issues, but damned if I can tell where it's binding up. Not between the plane and the fixed plane... I can easily get a piece of sandpaper inbetween the two at all deflections. Of course, I dont' have a 1/8" drill bit... I broke it somewhere. so I can't just run a bit down the hole and see if it's binding there.

One problem that I figured would come up. I tightened down the set screw, or should I say was trying to tighten down the set screw, and I stripped out my new threads. I didn't think the resin would hold much force, but I hoped it would hold more than that. Is there a way to strengthen those threads? I don't see a way to get any more meat for the threads to hold into, short of drilling through the back of the plane, and obviously I need enough torque on the setscrew to hold the plane in position. I guess I could try drilling through the brass rod and thread it all the way through.. say.. there's an idea.

[He Who Shall Not Be Named]

Your two problems are fixed with CA.

the holes in the stern and sides of the sail are tightened up by running a bead of thin formula CA within the bores and hitting it with accelerator. Build up and file with rat-tail till the operating shafts are a tight, non-interference fit through those holes.

Rebuild the stripped thread in the stern plane set-screw bores with CA, hit with accelerator and re-tap. The cured CA will be much more robust than the virgin cast resin. All the tip of the set-screw has to do is touch the flat of the operating shaft. Back off, wrench-wrist!

Go forth and sin no more!

David

[a1965l]

So.. got a binding stern plane, never good. Seems I have clearance from the fixed portion, but upon further investigation I find that my 1/8 rod slides in smoothly from the port side right up until this point:




You can see the misalignment. If I slide it in from the stbd side, it goes smoothly through the stbd side of the hull, and hangs up on the port side.



So obviously I have a misaignment, and it's on the stbd side fixed plane. This is the side that did not break off...


My first impluse is to work on the hole on the outer portion of the dive plane. Once I get the fixed plane moving smoothly, if it's not too rattly there, I'll just leave it. If it's rattly, then I'll work it with some CA and a file. I don't want to have to work the holes in the hull... as I'm fairly certain that the two outer planes aren't aligned. I did stick a 1/8 rod all the way thru when I re-attached the port side, but it went thru smoothly, but tight, and it rotated OK. Am I missing something here?

[He Who Shall Not Be Named]

File the hull hole on the other side till the shaft runs through the hull with no interference. Tighten up the gap between control surfaces and stabilizers with Bondo later. Get those planes to work freely.

David

[a1965l]

Really, I don't like builds that go perfectly. That means that you're not expanding your skill set, pushing your limits as it were. But then there are these kind of days...

First, I figured I'd mount the sail. Easy enough job. I'd use a couple pieces of Renshape to make blocks fore and aft, and then drill and tap them for bolts to hold the sail down. Easy Peasy. Would have been easier peasier if I had my belt sander up and running, but I have limits as to how much dust I'm willing to make inside the house. So, mark, cut, sand... man that stuff is nice to work with!





And done.. and then mark the hull and drill:



And then line up the sail, check alignment again, and mark the aft hole, drill, and then pin so I can mark the front hole. Who needs a drill press to drill a nice straight hole?



Not this guy. Oh, wait.. that's AFU. Looked straight while I was drilling.. but hey, it could be worse. I could have gotten it in the wrong place...



Oh, wait.. I did. Well, all is not lost. Easy enough to modify the renshape and get the hole straight and in the right place. I need that aft one right so I can mark the front. But wait.. there's more.. while I was CA'ing the blocks in the sail, I managed to let thin CA run down the inside of the sail and fix my fairwater planes in position. And not just any position. well deflected. Hey! Well, they needed to come out anyway so I could work the linkage a little bit.. it's smooth, but tight. That's not gonna cut it.

On a plus note I did some further clearance sanding in the hull and got both the yokes in and moving smoothly. Yokes, anyway. One of the dive planes is still binding, and only on half of its throw, from center to a limit. The issue is with the plane, apparently, as the problem travels with it. I dunno.. it's got plenty of clearance from the fixed portion, and not touching anywhere. and it does it no matter which piece of 1/8 rod I use. I really don't want to have to work the bore in the plane, I'd much rather that was a nice tight fit, but I'm running out of ideas. Opening up the hole in the hull did not help..





Anyway. At least it's a good day to stay inside and work on stuff like this.. need to get a little ahead as I expect a package tomorrow with pieces parts...

never time to do it right, always time to do it over.. at least thats what I've hard.

f

[He Who Shall Not Be Named]

"... I don't like builds that go perfectly"

WHAT'S WRONG WITH YOU??!!!!!

Lov'n that RenShape, huh? Me too.

Make both holes in the hull super-sloppy big -- keep enlarging them till the planes travel to extreme angles without binding. Then examine the holes (with the operating shafts still in place), note where you have to tighten them up with CA, and get to work!

David

[a1965l]

Since I can/t seem to remember my password to log on with my other computer, this will be a brief post. I received one of Nautilus's fm receivers today. Plugged in my Futaba crystal and it works with my 8u.. so that's a relief. I thought that was going to be a little bit more of a struggle. I did finally manage to get the dive planes free.. as it turns out, on the fixed portion, I needed to just touch the sanding block to the back side of the hinge block.. It looked to me like there was clearance, but apparently looks can be deceiving.

So.. work on the movable portion of the dive planes. I suppose three tries to get it right aren't bad.. I had to drill yet another hole in the dive planes, and thread it, to lock the plane to the shaft. The design is such that perpenndicular to the shaft the plane is very thin, and I wasn't comfortable trying to get that to hold. I drilled my holes at a bit of an angle, so that the setscrew is aft of the area of the plane that will come into contact with the fixed plane while being moved. This is easier to show that to describe, and of course I didn't get a picture of it. This complicated making flats, as they weren't perpendicular to each other. I made a flat and installed the plane, and then cut the flat for the yoke. Worked out best that way. But they all have flats, and the whole thing is fairly well aligned. Apparently, the secret to making a flat is to just use the cutoff wheel.. don't get fancy and try to flatten it out with a file. AT least not my files, anyway.

Now, I need to fill the two unused holes in one of the planes... does epoxy stick to brass? Or can I just wax it or grease it and the epoxy won't stick.. I suppose I could use some glazing putty or bondo, as well, but epoxy is a little more friendly to mix in the house.

Printing saddles as we speak.. they'll get installed later, once all the moving parts are installed and happy. No reason to make the job more difficult than it is already.... And Bob M. sent me the file to print the servo mount for the sub-driver, so I'll be cranking that out. I got electronics the other day, and with a receiver in hand it's time to start setting up the cylinder. Now, where is my soldering iron?



Yeah, I know, but cap screws are easier for this stage of the assembly. And I am aware that the shaft is a little long. will address that soon. You may notice the multiple holes in the port plane.. yeah, it took a couple tries.



Sooooooo close. but I think it's good enough.

Did the same with the rudders... no picture as it's essentially the same.

[He Who Shall Not Be Named]

To fill the hole just dab on a bit of thick formula CA into the hole and sprinkle some baking soda over it, repeat, then file smooth. KISS!

The hard part is done. Now for the horrors of getting the MSD outfitted with all that damned fool electronics horse-****.

David

[a1965l]

Not much to report the last couple of days. Tried to thread the prop shaft, apparently my harbor freight taps aren't up to the job, gonna have to source a more manly tap to cut into that SS shaft. The stern tube material is showing up tomorrow, so that's a little bit of a push. Question for you guys.. I'm going to use an intermediate shaft. The one on my Akula is made from aluminum with cut ends of a dogbone glued into it. Any reasons to not use Al for the shaft? Don't plan on the boat going into salt water on a regular basis, and that's really the only reason I could think of to make it out of brass..

My 3/32 brass rod showed up today.. bent in the middle, of course, but that's no worry as I really only need about 2" to fix the fairwater planes, which I, in fact, did. I also worked on the linkage to get it to move more freely. Got the sail part way installed, I need to fix the rear screw hole alignment. Might just be lazy and oversize the hole and use a brass insert, pretty sure I have a few of those sitting around here or there. Still need to go see HWSHBN and see if he'll hook me up with one of his vertical snorts to fit my narrow sail.

I do have a problem on the horizon, that I may not be able to work around. Placing the WTC into the hull with the ballast tank at the approximate center of the boat, I find that the rear of the cylinder is a good 6 or so inches behind my cut hatch. I may wind up cutting more of the top hull away to make a larger hatch. That really depends on whether or not I can rig up something to hold the pushrods and prop shaft in the correct position so I don't have to get fingers back there to make connections. The other consideration is that I may not have the room to stick the forward part of the cylinder into the hull, and then slide it backwards to make connections. I could space the supports to allow a couple inches wiggle room and then just put a pin in the lower part of the ballast tank.... probablly what I'll do, but then this is an issue for next week or later.

[a1965l]

So.. let's do something with the MSD, shall we?

I've settled on a 2300 Mah 3s Lipo for power, should give plenty of run time, and I have several of them so swapping batteries isn't an issue. I have most of the electronics on hand, and thought I had all the connectors I needed, but will get to that....

I didn't get pictures as I was intent on the job, but I pulled the pins from a servo extension and ran it and the power leads thru the ballast tank.. nothing to it. I'm only going to use one of the front servos, at least initially, so the other is a spare for now.

I'm not afraid to admit it, I'm not good at soldering Dean. All my electrics use the XT-60 connectors, the're a little bulkier than the deans, but solder fairly easy and come apart easier. Not to mention, they actually have the polarity cast into the connector body.. no more having to remember stuff. I wanted to be able to take the engine room apart, so using a connector between the incoming power leads and the powered components was a must. I thought about just twisting wire together and using an XT, and I may still go back to that, but I found some CC bullets in my meager supplies and thought.. why not? So...



The eagle eyed among you may note that I'm short one connector... it rolled off my table and into the HVAC vent. Gone. I may have the one I need on an airy-o-plane that's hanging in storage, but that can wait. Sticking the wire right into the connector works for now... An advantage to the CC's is that I was simply able to fill the backside of the connector with a pool of solder, and stick my pre-tinned wires right in. I can put another sleeve of heat shrink over the entire assembly when I put it together for real.

I'm working on modifying the servo mount design. I'm using servos that are apparently a little taller and wider than what it was designed for. They're what I have on hand.. so they're gettng used. I thought I had a decent selection of micro servos.. but no. I had a flood a couple years ago and lost a bunch of RC stuff.. guess those servos were among it. So I'm using waaay overkill HS-65 MG's, but they're what I have on hand. Again, may try to harvest some from a foamie that's getting retired.



I set up the pitch controller, which leads me to a question. Yeah, I know, another one. On the Akula, the pitch channel drives the bow planes. The pitch controller works the stern planes, and they are controlled by a trim knob. Does that sound like a valid setup for the 688?

And.. it all works.. not pretty yet.



http://<iframe frameborder="0" scrolling="no" width="1920" height="1080" src="https://api.smugmug.com/services/embed/9432509474_mTxkDMj?width=1920&height=1080&albumId= 209507443&albumKey=DL5cFw"></iframe>

Guess I need a little studying on uploading movies...

But one little bright spot... in my stuff I found a prop shaft... don't know what it's for.. but it's got m5 threads and it's the right diameter for my app... since my die wasn't up to threading the SS prop shaft I got, this is a nice find. Just need to cut to length... etc etc etc



Still lots to do of course. David, can I swing by and lay ahold of one of your vertical snorkel valves? I see where the horizontal one worked in a similar situation, but not knowing how much freeboard I'll have here it wouldn't hurt to have an option.. I can always bring one or the other back if I don't need it! Plus, the pump tubing..... anything special? Not tygon, I guess..

[He Who Shall Not Be Named]

So.. let's do something with the MSD, shall we?

I've settled on a 2300 Mah 3s Lipo for power, should give plenty of run time, and I have several of them so swapping batteries isn't an issue. I have most of the electronics on hand, and thought I had all the connectors I needed, but will get to that....

I didn't get pictures as I was intent on the job, but I pulled the pins from a servo extension and ran it and the power leads thru the ballast tank.. nothing to it. I'm only going to use one of the front servos, at least initially, so the other is a spare for now.

I'm not afraid to admit it, I'm not good at soldering Dean. All my electrics use the XT-60 connectors, the're a little bulkier than the deans, but solder fairly easy and come apart easier. Not to mention, they actually have the polarity cast into the connector body.. no more having to remember stuff. I wanted to be able to take the engine room apart, so using a connector between the incoming power leads and the powered components was a must. I thought about just twisting wire together and using an XT, and I may still go back to that, but I found some CC bullets in my meager supplies and thought.. why not? So...



The eagle eyed among you may note that I'm short one connector... it rolled off my table and into the HVAC vent. Gone. I may have the one I need on an airy-o-plane that's hanging in storage, but that can wait. Sticking the wire right into the connector works for now... An advantage to the CC's is that I was simply able to fill the backside of the connector with a pool of solder, and stick my pre-tinned wires right in. I can put another sleeve of heat shrink over the entire assembly when I put it together for real.

I'm working on modifying the servo mount design. I'm using servos that are apparently a little taller and wider than what it was designed for. They're what I have on hand.. so they're gettng used. I thought I had a decent selection of micro servos.. but no. I had a flood a couple years ago and lost a bunch of RC stuff.. guess those servos were among it. So I'm using waaay overkill HS-65 MG's, but they're what I have on hand. Again, may try to harvest some from a foamie that's getting retired.



I set up the pitch controller, which leads me to a question. Yeah, I know, another one. On the Akula, the pitch channel drives the bow planes. The pitch controller works the stern planes, and they are controlled by a trim knob. Does that sound like a valid setup for the 688?

And.. it all works.. not pretty yet.



http://<iframe frameborder="0" scrolling="no" width="1920" height="1080" src="https://api.smugmug.com/services/embed/9432509474_mTxkDMj?width=1920&height=1080&albumId= 209507443&albumKey=DL5cFw"></iframe>

Guess I need a little studying on uploading movies...

But one little bright spot... in my stuff I found a prop shaft... don't know what it's for.. but it's got m5 threads and it's the right diameter for my app... since my die wasn't up to threading the SS prop shaft I got, this is a nice find. Just need to cut to length... etc etc etc



Still lots to do of course. David, can I swing by and lay ahold of one of your vertical snorkel valves? I see where the horizontal one worked in a similar situation, but not knowing how much freeboard I'll have here it wouldn't hurt to have an option.. I can always bring one or the other back if I don't need it! Plus, the pump tubing..... anything special? Not tygon, I guess..

Yeah, come on over. We'll fix you up.

You're on the right track. Put the stern plane on ch-6, that's the 'flap' knob upper left on the transmitter face.

You're chugging along at a good pace.

David