The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by kscarguy, Feb 14, 2013.
Wonder of you could find a bus or motorhome graveyard to find pats or get ideas..
nice work, KS
Re: the "fine adjustments". These can be incorporated into the pivot bracket mounts on the sidewall. There should be positive stops (locators) at the bottom on both sides of the box to positively locate the cover when it's closed.
So, the lower arm's pivot adjustment will allow for alignment when closed, and the upper alignment will be a result of the upper bracket's adj.
Additionally, some vertical adj can be where the lower arm's outboard bracket connects to the cover.....the cover being able to slide up or down.
Yes, you'll need a bar/tube to connect from one upper arm to the other.
This connection should have some radial adjustment as well, so that both sides of the cover will come down together. The lower arm can't have this connection because it would be in the way.
One way to attach this tube is to make a short round locator that is installed on the upper-arm's pivot, The tube (either round or square) can be notched so that the tube end will slide over the round locator, yet still be "captured"
Each end of the connecting tube would then have a short arm (say 3" long) One arm with just a hole i.e. 5/16, and the other end a slotted hole to provide the radial adj as mentioned above.
great job on the door mechanisms!!
My second serious attempt. I moved the lower pivot point out of the door and inside the box. This means I don't have to cut any structure on the box (important stuff, structure!) I did a mock up using the outer skin to get a better feel for how it looks. The panel aligns great, opens perfect and lets me have the needed room to notch the back of box so I can move the rear spring mount forward.
The downside is that it does not seem to lift up quite high enough. It is usable, but I'd really like to get another two inches of lift if possible to make putting a cooler into the box easier. Looking straight in, there is 16" clearance, at an angle 17.5"
So, I'll take a deep breath and give it another try.
Now I remember why I quit working on it... trying to figure this stuff out is frustrating.
GATZ!!! you big ol' genius!!!! I have been racking my brain on how to build the connecting bar. You just solved the problem....THANKS!!!
Great work and ingenuity on a great idea! Hang in there, if it was easy everyone would be doing it!
I spent a great deal of time doing geometry today. What I discovered is that to gain 2" of door lift, the door also moves outward 1" away from the box. This is not good.
I can only think of two things to change:
1. Move the entire boxes outwards - this would help the outwards distance issue that is caused mostly with trying to clear the bed edge.
2. Modify the lower structure of the box - I discovered that the lower I can locate the bottom hinge point, the higher the door can go and also the more inwards it can be located when open. As much as I don't want to cut the bottom folded edge of the box, there might not be any other solution. Perhaps I can add structure back in around the back of the hinge.
Can you change the shape of your top linkage and add a bend to your lower link? The pivot points can stay in the same relative spot, the door may be slightly out farther when opened, but you should be able to get the extra 2". I would maybe start with your door up where you want it and see what you need to change to the link to keep the pivot. Good luck with the geometry
I discovered a flaw in my original assumptions and by removing that flaw, I think I have a workable solution. It has to do with a jamb built into the inside of the door.
I had planned to attach brackets to the insiode of the door, but then I discovered that I can actually attatch the arms to the jamb area of the door. That results in the doorshifting inwards by a full 2".
I also layed out the upper arm to hug the top surfaces and changed the bottom hinge point to the bottom of the door. That means I will need to notch the support across the bottom of the box and reinforce the structure. But without lowering that mounting point, I can't get any height on the door.
The solution is not perfect, but 92% good. In order to improve upon it, I would have to move the boxes outwards. That would change the looks of the truck...so I think this is the answer. Time to build it for real.
What to make the arms out of is the next decision. Solid Steel, Aluminum, Channel...any ideas?
(Pictures show : inner door jamb, arm locations with bracket vs. inside jamb, and how much closer door moves to bed after relocating mounting point into the jamb, and how the lower hinge will run into the box structure)
I need some materials schooling.............
For these arms, what is the best material to use? They are about 1 3/4" wide. Should I use 1/4 or 3/8 steel or 1/2 aluminum or what? Any help would be appreciated. i am looking into having them cut with a water jet. (Come to think of it, I'd better design the other brackets too and have them all cut at the same time.)
Make 'em out of the TOUGHEST yet WORKABLE material you can. I think 3/8" mild steel plate would be best. It'd SUCK to bend an aluminum bracket out on the road and not be able to close the bin!
Good point. Even at 3/8", they probably would only weight a little more than a typical bumper bracket. What about stainless steel, would it hold up? It could be polished and that would look nice. I wonder if drilling it (like a drilled front axle) would weaken it too much?
How do I do it...
I need to make the lower arm pivot point (on the box) fully adjustable, like chucking something into a lathe...how do I do it?
You could make the mount pivot end have a round hole, then have a round stepped plug go into that hole with an offset hole for mounting, then it would work like a cam that you could loosen, rotate and re tighten to move the bracket in, out, up or down fairly easily.
The shaft needs a spacer on it to locate the arm away from the edge of the box, so it will clear the drip rail. I am leaning towards making the spacer threaded and mounting the shaft in an oversized hole and using the spacer to tighten the shaft in place. It is not really a "fine" adjustment, but would work.
Project Update - I found a local company that can cut my hinge arms and other brackets with a water jet for about $18-$25 per piece. The edges will be smooth and ready for polishing. I think that is affordable considering what I am doing and the complicated shapes. They can make the parts working off my templates or off line drawings that they scan into a computer, so that also a plus.
Next step - make high quality line drawings...good thing I am an engineer with a large drafting table.
I also want to thank a fellow HAMB'er for passing on the number for a local machine shop so I get the mounting studs fabricated.
These arms do not have to be in the same plane; they can "slide past" each other as long they allow the up/down positions you're looking for.
Not to complicate things, but the weight of the door and mechanism may necessitate gas springs, equals on each side. When the door (or cover) is almost closed, the gas spring should be near collapsed (but not bottomed out) and the mounting point for the clevis on the lower arm should be near to being in-line between the lower pivot point and the gas spring's lower anchor point which might be down in the lower rear corner of the box.
Some common tail-gate springs would probably work.
Agree about the 3/8" thickness....seems substantial. Beings the arms will be water-jet or laser cut, you could design in some slots/holes to kinda dress it up.
Also, as the door nears closure, there should be something on the sides such as small rubber bumpers on the box that keep it in alignment.
The lower arms could have integral tabs that are bent slightly inward to help guide the door.
Might consider having sheet-metal panels made up that keep articles away from the arms.
All good points and I don't think you can make it much more complicated than it already is...ha!
I have not posted the latest design. It is really quite interesting. The hinges "mate together" at the top of the travel. It would be a neat place to cut a design in that is partially made from each of the arms.
I found this design on the web that I thought was neat...
The hinges will be hidden behind the door, and not visible unless you're inside the box or on the flatbed looking down, right? If that's the case I wouldn't spend much time putting intricate designs in them. Intricate designs will also add cost to the waterjet mapper's time tracing your drawings, and cutting material away only weakens the structure itself.
Just my .02, but I would make them functional first, then "pretty" second. Actually, I probably would never get to the "pretty" part.
I am looking for ideas...what is the best way to mount the hinges into the boxes?
My thoughts are to fabricate a 3/16" steel plate large enough to locate both of the hinge pivot points inside the box. I would make this entire plate adjustable up and down with slots. That would allow for up and down door adjustment.
The lower hinge pivots would adjust on these plates like door strikers, (an oversized hole and a threaded captive plate on the back - imagine a loose cage nut). That would allow for 2-axis adjustment on the lower hinge location and allow for adjusting the door bottom in and out.
I am not sure the best way to attach the plates to the boxes in a method to keep them square and allow room behind them for the captive plate and bolt heads.
I think the picture you posted is real cool. Don't go to all the trouble to make laser cut hinges then make them plain jane. Church it up a bit.
The latest design. I spent a lot of time trying to work out all the bugs. There is not a lot of room (length) for actuator and spring cylinders. Also there is a 140 degrees of rotation to the hinges and connecting bar and that makes getting the angles on the brackets to work correct with the actuator and cylinders difficult.
Here is a pic of the MCI system
Thanks for the pictures. Perfect timing as I am working on the gas strut design. On the bus pic, it looks like the gas strut is mounted on the inside of the bottom arm, that means when it is closed, the strut actually rotates past centerline and tries to rotate the hinge inwards (very slightly). This is good to know.
The struts come in various sizes and strengths, so I stopped by NAPA and the counter guy copied the catalog pages for me with all the specs (lenght, force, etc.)
Since they come in various forces. I will have to weigh all the door parts and based upon the cylinder mounting location, calculate how much force is needed to hold up the door...I think I need my statics engineering book for this one. They are just too expensive to buy and try.
Mcmaster.com also sells the struts. They have a variety of end connections too.
Do I need latches if I use linear actuators?
I use a pair of actuators on my '40 trunk lid which to say the least is very heavy, but there is no need for any latch as when they close, they stay closed.
I would so you could lock them up for the security of what you have inside. And it would really be bad if they were to come open by accident.
I did this with the Paint program so it is not too acurate, but it explains what I am building.
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