The Poet Creek Express - Foamie Hybrid

[ghcoe]

I did give that a thought. I would still have a problem with head room and to get the hatch high enough I would still have problems. Also more seams to try and get dust proof. That is another reason I do not like the barn door idea too. I think I have talked myself into just dealing with a hatch. I suppose I should start a thread to keep it simple here. Thanks though.

[KCStudly]

Everybody is welcome here. No skin off my apple , though I do appreciate your consideration.

[KCStudly]

I spent some more time on the hatch actuator arrangement this evening. Once I reduced the swing of the hatch to 65 deg I was able to locate the ideal anchor point of the lower pivot bracket at the cylinder end. It ended up being a little below the lower galley shelf and a little behind the bulkhead very near one of the bulkhead xmbrs.

So from there I fudged the location forward and up a little so that I could tie into the xmbr using the lower bracket design shown below. I plan to add an additional block under the xmbr (not shown).

Here is an overall shot with the hatch closed.



And here is one with it open.


And here’s a close up of the geometry.


{I hope these images are clear enough to see. I accidently exported them from Inventor as bmp’s and had to convert them to png. If they are fuzzy, I can try again another time.}

The bulls eye’s at the end of the green lines, connected by the green arc (32.7 inch radius), represent the center of gravity of the hatch in the closed and open positions. The hatch is raised 65 degrees from closed to open. The green line in the middle represents the midpoint of the hatch travel.

The red arc (9.3 inch radius) represents the path that the rod end pivot point travels through. The red radii originate at the hinge and indicate the starting and stopping points for the rod end.

The 11.1 deg difference between the red and green is the compromise between the ideal 90 deg dwell at mid stroke that was made to put the lower anchor point on the xmbr.

I may try another version where the lower bracket is raised enough to get the cylinder above the shelf panel, but, due to the retracted length of the actuator, the higher up the actuator is the further to the rear the rod end must be, and the worse the angle of force gets. The actuator has the most strength when acting at 90 deg thru the dwell point. The longer upper brackets and the lower position of the lower bracket help this angle stay close to 90.

The model has the hatch weight at 48 lbs before any allowance for canvas, paint, taillight mounting and taillights, galley light, wiring, paper towel rack, screws, latches, the actuator brackets, etc. What I am trying to say is the hatch will get heavier. The ratio between the CG and the rod end bracket-to-hinge center radius is 32.7 / 9.3 = 3.5. So without even considering the force vectors (loss of power from being away from 90 deg), friction, direction of gravity, etc. the pair of actuators must lift over 48 x 3.5 = 168 lbs.

Looks like it will definitely take two actuators, and before everything is said and done, that may not be enough. Sure would have been nice to have the longer 12 inch travel actuators.

I did attempt to do an FEA to see what the software would say the load was on the actuators (accounting for gravity and angularity), but my desktop at work didn’t have enough nut to get the job done w/o grinding to a halt; which is where I ran out of time. I’ll try again using a mock up with just the hatch and related actuator parts, and close the big camper model before running the FEA next time.

Peace.

[Wolffarmer]

What KC said.

Reminds me the time I spent building those big rotary snow plows. One shift the foreman sent me to put on a hydraulic ram that is a part of the aiming part of the snow exit end of the machine. I had never done it before as I was new and never seen it built before. He said that they just tack it on, try it. If it don't work, break it off and try again. He said it usually takes from 4-8 hours to do. I felt good when I got it in only 5 hours. I then asked foreman if I could do the next one as I had an idea. So another one came along a few days later. I dove into it and just under an hour later i asked the foreman what he wanted me to do next. He was floored. Shoot it was just a matter of a little bit of geometry and drawing things out. The really really bad part of this all is the machines had not changed much since the 1930's, that I know of and this shop had been building them since the early 60's and this was about 1983.

I would like to know how to use Sketch Up but I get to easily distracted when I am trying to teach myself. Guess I will just have to build me some old school drafting equipment. I still have the tools and scale. I just need the t square and triangles. For what I need would not have to be fancy.

Randy

[RandyG]

Is that 48 lbs the total weight of the hatch or did you add in the leverage from that specific point? Leverage is your enemy!

[KCStudly]

The 48 lbs is what the whole hatch weighs in the model as it sits (i.e. nude and not rigged out, to use a nautical term).

The ratio calculation and 168 lbs is a rough theoretical estimate of what both actuators would see if the hatch did only weigh 48 lbs. So 84 lbs each for two actuators. the problem is that for every pound that gets added to the hatch from here on, each actuator will see about 1.75 lbs added.

Reduce the rating by a couple of percent (cos 11.1) for the angularity, and that means that another 9 lbs of hatch weight and I have exceeded the rating of the actuator. And that's not the worst case; I should really de-rate more for the start angle.

I suppose I could be off somewhere, but if so, I don't see it at the moment. I mean, it kind of makes sense when you think about how many people have had to go and change their struts to stronger ones; it's very easy to underestimate all of the factors that go into figuring the true load on the struts.

Well, I do have four (4) of the actuators. How do you all feel about me adding a rib and using three of them? I might have a little bit of shelf space left over for spices and Bisquick.

[KCStudly]

Thought about going out to the shop this evening and keep going on the street side wall, but when I called Karl to see what was up he reminded my that it had barely gotten above freezing all day; downstairs shop temp was only 46F during the day, so upstairs was probably 5-10 deg less. When I left work the Ford had the outside temp at 29F, so no. I will try to get an earlier start tomorrow and get there for midday warm up.

Hatch strut plan is to keep designing and select hydraulic spring struts as a backup plan; add blocking as required to support that option; then build in the actuators as I go and see if they can cut it. If not, add the struts to supplement, then decide if the whole thing is too hokey and whether I want to remove the actuators. Aside from a few holes to fill in the bulkhead and ribs (and my time) there really is no downside.

Wish it was warmer. Every cold day is one less day to build between now and the next Poet Creek camping window (July, August, 1/2 of September). There is so much seasonal snow there that it doesn't all melt sometimes until late in June, and flies again as early as September.

I sure am enjoying reading (here on the forum) about other peoples adventures in Idaho (sorry, can't remember the thread at the moment...guy went winter wheeling off pavement with his TD and a group of others).

Randy (Wolffarmer), I sure envy your free spirit and wanderlust. And another thing; how the heck are you able to remember when you went where? You always seem to be able to recall the details of your many storied travels. I can't remember what I had for lunch last week, it seems, let alone what I did ten years ago, or more.

Oh well, let's hope that I can get something done this weekend.

[Wolffarmer]

Randy (Wolffarmer), I sure envy your free spirit and wanderlust. And another thing; how the heck are you able to remember when you went where? You always seem to be able to recall the details of your many storied travels. I can't remember what I had for lunch last week, it seems, let alone what I did ten years ago, or more.

Oh well, let's hope that I can get something done this weekend.

Thanks but is no big deal. It is the context of what all was going on at the time. Seems to be easy for me.

Randy

[ghcoe]

Hey Idaho is a great place to have a TTT or TD. Looking forward to getting mine built.

[KCStudly]

I'm following along, ghcoe.

I know what you mean Randy. Seldom does a day go by that I don't recall some pleasant thing from the year I spent in New Zealand in '82.

Now about the build: I made it out to the shop today. GG’d the long bulkhead blocking into the recess that I previously routed into the interior side of the street side wall. Shown here under plastic lined freezer paper, four (4) tubs of stainless steel screws (one of Karl’s business collaborators over bought on a project), and a pile of boxes of spooled MIG welding wire.



While that was kicking off I switched my attention to the forward and mid cabin blocks that I had glued in previously. After trimming the raised up glue with an old serrated steak knife I decided that the palm sander was the best way to knock these back down fair. The GG had pushed some of the blocks up here and there and the palm sander pad was about the same size as the blocks, so there was less tendency to accidentally remove foam from the surrounding areas (which was easy to do without trying).



Here are the mid cabin blocks after fairing, looking from the top of the wall down.



Sneaked a peek under the freezer paper at the bulkhead block and was not pleased to see that it had pushed up a little more than 1/8 at the top rear (right side in pic), less at the top front (left side in pic).


It wasn’t as bad at the bottom; just 1/16 at the rear and more or less flush at the front. Seriously thinking about switching to PL or thickened epoxy at this point.

Here it is right side up looking from the bottom sill up toward the roof. I have started to trim the excess glue with the knife, though the small Sureform plane would have worked good, too.



I used a combination of the powered hand plane (tended to gouge a bit), the hand bench plane (very controllable), the 10 inch homemade sanding block with course belt sander belt, and the hand held powered belt sander to knock it all down.


It’s getting there, still a slight crown in the middle.


And here it is in pretty good shape after some more sanding and a little clean up.


Yvette and I went out to dinner with Chris and Karl to celebrate his birthday (which was yesterday). We went to Michael Jordan’s Steakhouse at the Mohegan Sun Casino. Very nice meal, yet way over priced by casino inflation. We had the signature garlic bread with bleu cheese sauce for mopping (yum). I had the beet salad (mostly red with some golden beets, topped with crushed hazel nuts over a bed of mild goat cheese, with a few drops of reduced balsamic vinegar on the plate and fresh herb garnish), filet mignon, and we shared sides of lobster mashed potatoes (lots of big pieces of lobster claw meat), asparagus with a béarnaise sauce, and creamed fresh spinach that was served in a mini CI skillet with a parmesan crust (the spinach was not over cooked, and, pleasantly not very creamy.

Chris ordered a couple of very expensive bottles of Cab-Sav that were enjoyed thoroughly.

The waitress noticed the birthday card that we had given to Karl, and so brought him a mini serving of their 23 layer chocolate mocha cake (which Karl shared). I ordered the baked Alaska which was a generous serving of homemade tasting vanilla ice cream covered with a delicate seared meringue surrounded by caramel sauce and candied clusters of sliced almonds, which I also shared.

[mezmo]

KC,

If you don't quit eating, you'll never get this thing built ! Ha !

Good to see you enjoy your 'grub' as much as the build - relishing them both.

Cheers,
Norm/mezmo

[lukeyslide]

KCStudly Epic build. Unbelievable amount of effort into this build, Well done indeed You have done pretty much everything from scratch. Hitch is an artwork in itself. O and would love to come over for dinner at your next feast. Hungry just looking at the photos

Cya Lukey

[ghcoe]

Too bad about the GG lifting the wood. Looks like it makes for a lot more work and hassle. I have worked with GG a bit and find that it is a bit of a art to work with. I have done no big projects so I really do not know what to expect. With my small projects I have found that using different amounts, with and without water, gives quite different results. I do know that with a lot of moisture that it foams up quite a bit and you only want to use a small amount of GG.

I have read about PL300. Has anyone used it here? I was wondering how it would be to sand over the GG.

[KCStudly]

Thanks Norm. Yeah, we don’t eat that way all the time, but we do enjoy it when we do.

Lukey, Thank you for the very kind words. I really appreciate your recognition of the amount of work put in. I seriously considered building a weekender to get it done, but got sucked in by all the cool ideas. I suppose I could have thrown something together much faster, but I kind of get hung up on the details and there’s not much point in putting lipstick on a pig, so in for a penny in for a pound. If there ever is a #2 it will be more traditional and thriftier. The hybrid construction should come out relatively light, but I seem to be having more difficulty getting the foam to do what I want than the wood; keeping it fair, dent and gouge free. Surprisingly, I seem to be doing well with the wood work and am happy with speed and end results I am getting there. Not that I am unhappy with the foam; it’s just not as “fixed” (durable or uniform) as the wood.

If you can make it here from Brisbane, I’d be more than happy to feed you! My host family that I stayed with for my year in New Zealand moved to Brisbane after I returned home. It’s a small world.

George (ghcoe), Yeah, I suspect that I am using too much water. I have spread the GG with plastic credit cards fairly thin. Usually I run a few strands of glue, spread sparsely, and then I add a bit more here and there to achieve an even coat with no dry spots (I suppose I might be letting some excess build up in the corners… maybe I should cut the radius corners off of the spreaders). My spritzing water bottle does tend to spray a coarse splatter, rather than a fine mist, so I have been spraying the wood side and wiping down with my rubber gloved hand, just damping the wood evenly. With the cold temps the GG seems to take a while to react, and the temptation to spritz the glue side becomes overwhelming at times, so my problems are probably self-induced. I will have a talk with the operator (me) and see if I can get him to use less water.

I have very limited experience with PL (the brown stuff…4000?) putting up FRP in mixer rooms, so can’t really comment there.

Thank you all for watching and the support.

[ghcoe]

I have very limited experience with PL (the brown stuff…4000?) putting up FRP in mixer rooms, so can’t really comment there.

Oh. Not sure where I read about PL300 then. Thought it was some where on here and when I saw your mention of PL, I thought of the PL300. I hate when I read so much I can't remember anything.....

So if no one here has tried PL300 maybe it would be something to look in to.

http://www.loctiteproducts.com/p/pl_ca_ ... hesive.htm