Tucson tortoise: Edit for photos

[noseoil]

Get a piece of cardboard big enough for a full scale layout, then just do this. Show the "door open & door closed" location you want full scale. Make sure you include anything which might be in the way on your layout (counter, upper cabinet doors, paper towel holder, shelf, etc). Look at McMaster for their list of closed-open lengths, just to see what's available. My strut is 29 1/2" open & 16 1/2" closed, 100#, stroke is about 12".

1 (Arc #1) - Measure from the center-line of the hinge pivot to the place the strut attaches on the hatch in the open position. Strike an arc that swings down from the hatch to the side panel inside the opening, past where the hatch is in the closed (stowed/closed in your case) position. This shows the two points the strut is attached on the hatch in their two positions. (see Step A1) It goes from up at the top (open) position attachment point, down, and through (past) where it will be when the hatch swings shut. A simple arc, nail & stick, pencil clamped to the stick, trammel points, use what you have. The upper "point" is the hatch in the open position, the lower point is the hatch in the closed position.

2 (Arc #2) - From the "lower" position attachment point on the hatch (the hatch is in the closed position, where the strut mount is, relative to the side panel when closed, mine is an inch from the inside surface of the hatch), strike an arc which is the closed length of the strut (but add about 1/4" - 1/2" to this short length, so the strut doesn't "bottom out" when the hatch is completely closed, or 17" in my layout) up & down in the side panel. (see Step B1)

3 (Arc #3) - Now use the extended length of the strut (29 1/2" for mine) and strike an arc from the top of the hatch attachment (in the open position) across the panel so it intersects the arc from step 2, the short length arc. (Step C1)

You now have a point on the side panel where the closed strut arc (plus 1/2") intersects the arc from the open hatch location with the strut fully extended (29 1/2" arc). That's it, you're done now. Screw it in and it will have to fit.

The image below shows what happens when you move the points around, 2 different cases. The upper one mounts closer to the hinge, the lower one is farther away. Hope this makes sense to you. PM me off list if this is too difficult to understand. The key is a full scale layout in pencil first, then use magic marker when you have selected the correct strut length from the list that actually works for your application. I don't pretend to be able to do the load calculations on this stuff or a vector analysis to show moving loads, but I can work from a simple line drawing with three different arc lengths, which is all this layout really is. Remember, there are an infinite number of possibilities for any given closed-open length strut. It just depends where you want to that the attachment point on the hatch. The closer to the hinge point the strut attaches, the more powerful the strut needs to be to lift it up and hold it there.

P.S. here's the way to do it, new image

[working on it]

Thank you for the detailed descriptions of "how to do it". Really good methodology, IMO. I'll be interested to see how it works on my quite different hatch design, in allowing for the limited mounting space and the extreme opening angle. I had already formulated a scheme (with scale modelling, triangulation), and bought two gas springs last night online. I'm committed to that as a plan of action, for good or bad. When I have them on hand, and using the "adjustable" curved brackets I also bought (allowing for some variations in measurements and materials), then I'll see if my method comes close as yours surely will. I will "exhaustingly" report my results. Thanks for taking the time and effort to post your work, it'll be used by many builders, I'm sure.

[working on it]

Thank you for the detailed descriptions of "how to do it". Really good methodology, IMO. I'll be interested to see how it works on my quite different hatch design, in allowing for the limited mounting space and the extreme opening angle. I had already formulated a scheme (with scale modelling, triangulation), and bought two gas springs last night online. I'm committed to that as a plan of action, for good or bad. When I have them on hand, and using the "adjustable" curved brackets I also bought (allowing for some variations in measurements and materials), then I'll see if my method comes close as yours surely will. I will "exhaustingly" report my results. Thanks for taking the time and effort to post your work, it'll be used by many builders, I'm sure.

As I promised, here are the results of my successful hatch-lift-assist install, using one off-center mounted gas spring, rated at 150 lbs force. http://www.tnttt.com/viewtopic.php?f=21&t=61432&start=15#p1101237 Thanks for your encouragement and help!

• off-center single spring 150 lbs
• angle of opening adjustment extensions
• measurements and weights involved

[noseoil]

Did a little more on the build this weekend. Worked on the walls & glued up the 1/8" birch for interior panelling on both frames. The 5X5 Baltic birch is nice to work with, seams are at the port holes. Trimmed with a router (flush cut bit & rabbet cutter). Here are a few progress pictures. Just plugging along.

Used the deck for a work table, red rosin paper to protect the finish on top. This is the color. The unfinished area is for the second layer of 1/8" in the galley area. It needs to support the battery & cooler. Extra blocking was added in the frame for support & hard points.


Here are the two different cuts with the router.



Stain & a first coat of urethane on one panel. Will do two coats of urethane for the walls. Stain is a gold-maple. I want the interior a light color, so it isn't too dark or cave-like inside. This should be about right once it's assembled.

[KCStudly]

Looking good.

[S. Heisley]

You're getting there....nice design!

[noseoil]

Worked on a couple of things. Put another coat of urethane on the wall panels. My son's old cat decided to stroll across the top of one of the panels this morning after I had finished. Nothing a little sanding & re-application won't fix. The cat's 19 now, so as senile as he is I guess it's ok.... He probably doesn't remember doing it anyway by now.

Also, while the cat was staying busy on the porch adding his finishing touch to the wall, I did some basic wiring for the tongue box & a conduit run to the back end. Here's the junction box set inside the tongue box for the 7 pin connector harness. The black left side cable is the "in" side from the truck, the gray conduit on the right feeds the back with a #8 hot, back-up lights, electric brakes & 4-wire loom for running lights. The loose wire is a ground which attaches to the tongue box with a 1/4" bolt. Fitting this much wire into those connectors was a bit challenging.


Here's how it goes under the frame and to the back.


Here's a detail shot of the back. The third leg goes up through the deck & into an electrical chase in the galley bulkhead to feed into the PD4045.

[Sheddie]

Worked on a couple of things. Put another coat of urethane on the wall panels. My son's old cat decided to stroll across the top of one of the panels this morning after I had finished. Nothing a little sanding & re-application won't fix. The cat's 19 now, so as senile as he is I guess it's ok.... He probably doesn't remember doing it anyway by now.

Also, while the cat was staying busy on the porch adding his finishing touch to the wall, I did some basic wiring for the tongue box & a conduit run to the back end. Here's the junction box set inside the tongue box for the 7 pin connector harness. The black left side cable is the "in" side from the truck, the gray conduit on the right feeds the back with a #8 hot, back-up lights, electric brakes & 4-wire loom for running lights. The loose wire is a ground which attaches to the tongue box with a 1/4" bolt. Fitting this much wire into those connectors was a bit challenging. [/img]

Hi Tim,
No matter how old the cat is they have the rite to do whatever they like.
Nice job on the wiring. Must have been a tight fit through the conduit as well.
Frank.

[noseoil]

Frank, yes, tight squeeze to get all of it in and turn the corners, but it's done, so it's all good. Worked on the deck again & a few odds & ends this weekend. I had to make a hole in the deck for the gas line entry (1/2" black pipe, runs under the deck from the tongue bottle) & one for the the battery box vent, which is on the bottom of the box. Also added a second layer of 1/8" (3mm) Baltic birch to the galley deck area to beef it up a bit.

I cut the holes with a router, then used grey electrical conduit couplings for my bushings. After the holes were made, I roughed up the bushings on a sander & used some 5-minute epoxy to pot them into the deck from the bottom side. When the epoxy kicked off, I glued the next layer of 1/8" ply to the galley area & used a flush-cut bit to open up the holes again. Finally, finished up with some stain & urethane to seal things from moisture on the top. Still need to caulk the bottom side with silicone seal to keep the water out, but here's how the finished installation worked out.

The small hole next to the vent is for a 5/16" eye bolt. There will be 2 eye bolts for the battery box hold-downs (regular automotive type of "J" bolt fasteners), so it doesn't move around too much on the road. The bolts all have "hard points" which are just blocking added to the deck at areas and are drilled for holes & fasteners. I also found some 1/8" neoprene gasket material for a pad, which was glued with contact cement to the bottom of the battery box for vibration damping & chafing.

Bottom of the gas line bushing, about 7/8" I.D. (normally used for 1" conduit)


Deck, top of bushing with eye-bolt hole next to it. The light colored line is the dado slot for the 1/4" galley bulkhead (1/4" or 6mm Baltic birch).


Bottom of the large bushing used for the battery vent (a 2" conduit coupling, sliced & shortened to fit). Ready for the silicone seal now.

[capnTelescope]

Tim,

The Tortoise is shaping up nicely.

Thanks for the graphic in the post at the top of the page! I knew there had to be an easy way to figure out where the strut mounting points go. I had to slap my forehead when I saw how easy.

You saved my life. I owe you a beer!

[Sheddie]

Hi Tim, how are things progressing on the build, haven't seen anything for a while.

[noseoil]

I'm finally back! Long story short, the winter break lasted about 4 months, but all is well. Here's what I've been looking at since December, at least it stayed dry under the tarp, with the winter rains being back to "normal" here. It was a nice, wet, winter for a change. Lots of rain & the desert is blooming again. Seems pretty dismal to see it like this, but today I uncovered it, opened up some boxes & did a little bit of work. Feels good to be back again & working. I may throw out a nearly new tarp. Every cat in the neighborhood must have been marking that tarp & laying claim to the corner of the trailer. I really dislike the smell of cat piss, especially when it has a chance to age & ferment a bit......


I did the last penetration in the deck for the galley this morning, electrical line from the front box, 3/4" gray flexible plastic conduit. I had put in plastic bushings (electrical conduit parts) as liners for the holes & then bedded them in epoxy, but was lacking one when I buttoned up for the holidays.

Here's a detail shot of the corner, the dado for the 1/4" galley bulkhead, and a piece of scrap baltic birch which will be the actual bulkhead once it's done. You can also see the elevator bolt I "modified" slightly to keep it from hitting the side-wall panel, once it's set in place in the dado, glued & screwed. I'm going to use epoxy to set these bolts for the final installation, to keep them from spinning in their seats and as a water proofing measure.


Finally, here's the mock-up of the galley deck & bulkhead, showing the three holes in the deck. The left hole is for the gas pipe (1/2" black pipe), the large center hole is for the battery box bottom vent & the right side is the pass-through for the electrical conduit. As it turns out, the 3/4" gray flexible conduit (used in home building) is a good size for a 1" coupling (the rigid gray EMT). Once it was in place & potted, I used a flush-cut bit on the router to trim the inside lip out of the coupling, then make the final clean-up pass on the deck. Had a slight "chewing" of the back edge with the router, but it will be recoated & covered with aluminum, so no biggie.

[Sheddie]

Hi Tim,
Good to see you are getting back in to it.
Seeing that snake makes me feel glad I live in New Zealand, we don't have anything like that here. I suppose you never know where one might be hiding.

[rebapuck]

Good Lord!! I kept looking and looking at the first picture. Couldn't see it at all. It would have given me a heart attack. Even seeing it for the first time days later.

[S. Heisley]

It blends very well with its surroundings. Thanks for sharing.