my tower rack design - whatcha think? (prototype made)

[Wallrat]

Here's the idea I had. Basically its using a bungee system to hold the board in, except the bungee is internal. The outer tube is stainless, with another tube inside that has an O.D. just smaller than the outer tube's I.D. The lower board mount is welded to the outer tube while the upper mount is mounted to the inner tube through a slot cut in the outer tube. Kinda hard to explain but hopefully you'll get the idea from the picture. The bungee will be connected to the lower end of the inner tube and the other end held in place by a knot tied on the outside of the mounting plate. The whole thing will be rebuildable to facilitate the replacement of broken bungees. Additionally I think I'm gonna use some of that liquid rubber "tool dip" stuff to coat the mounts.

Whatcha guys think?

[super4011]

nice idea, its preatty creative

[nan0]

Not a bad idea at all. Couple of comments/questions -

Will you have two of these per board?
only needing one would be sweet.

Any issue with the board mounts not fitting different boards?

Is the upper mount spring loaded so it opens once the bungee is released? Could use the bungee - tie the bungee to the outer end of the tube, tie it to the outer mount a few inches in, then bring it down to the knot. when you pull, the bungee is pulling the mount closer. when you let go, the small section of bungee between the mount and the end of the tube is pulling the mount back out.

what about rope instead of bungee? On sailboats, they have the rope clips that you just pull on the rope, slip it in, and it holds real tight. no idea what they're called.

Most importantly, when's it gonna be done I wanna see it in action!

[Wallrat]

Interesting idea Nan0. With this design I'm trying to eliminate hanging ropes or bungees. The mounting plate in my diagram will actually bolt onto the rack mount, so the exposed bungee knot will be completely out of view. Not that your idea is bad - top notch man! That sailboat item is called a cam, and yeah that would definately work, but you'd have to have exposed rope (or tuck it up somewhere out of sight but easily retrieveable(sp?). My original design would permit you to just pull the upper mount a little and the bungee would stretch thereby allowing you to pull the board out. As is if the rack is empty then that upper mount is just gonna be sitting there. I'm hoping that the bungee has enough rebound that it will hold the upper mount to the lower end of the slot so it isn't bouncing around. You could definately also do it as a single unit. I'm debating this right now myself. Doubles would be easier to make adjustable for different binding seperation, but its possible with a one mount per board setup as well. I cut a few pieces today and scoped out the metal I think I'm using. Primary construction probably won't really start until the tower is done. So next week sometime I should have a tower with racks mounted on my boat

[Paul-o-rama]

If i were you, I'd be worried about the bungee loosing stretch over time and not holding the boards in

[aceyx]

[joedirt00]

OK Wallrat,

After seeing some of your posts you definitly have the abilities. One thing to consider adding is some kind of swing in mounts. Your rack design is great, Very impressive thinking. It would be cool to swing your racks into the boat to get your boards out though.

Nice job.

[vawakemonster]

you might want a piece that goes inbetween the boots like in normal racks incase of sudden jolts foreward/reverse. this rod or bungee would keep the board from flying foreward off the rack or slipping backward....

[-=LoneStar=-]

I've got two suggestions:

1. Try to incorporate some kind of plastic between the two tubes. It will make it easier to slide and less prone to annoying metal-on-metal rattling.

2. Create a notch in the slot in the outer tube so that by opening the rack to it's full extent and twisting the inner tube within the outer tube, the protruding piece can slip into the notch and lock the rack in the open position. This should make it a bit easier to deal with getting boards in and out, especially if you go with double mounts.

[Wallrat]

Great suggestions everyone! Definately getting some ideas for improvement on my original design.

LoneStar: I didn't even think about the metal on metal factor. I'll definately see about a plastic insert. Notching the outer edge is also a great idea. I was actually thinking about connecting the two upper mounts (if I go double) with a rod so that I could pull both mounts out with one hand. I'll have to think of how I could still do that and make the upper mounts lockable in the out position.

vawakemonster: If the mounts are both inbetween the bindings, wouldn't the bindings themselves provide protection from forward reverse movement?

joedirt00: Already in the works. I had thought about pivoting mounts beforehand. I'm just not sure yet if my tower will allow for them. If it does, then I'm all over it.

aceyx: Excellent idea on keeping the slot short enough to keep tension. I think I figured out a way to pull the mounts out (see above) but I think its gonna need some modifications if I try to make them lockable in the out position.

Paul-o-rama: That's why I wanted to make them fully rebuildable. I can replace the bungees as they become worn.

I took a look at some of the (free) metal we have down at the shop. I've got some stainless pipe as well as some teflon I could mill for some bushings. I'm not sure however if I want to keep the slot idea. It'll mean some extra work in order to keep them fully rebuildable. Also, I'm not sure I'm going to use bungee. I know where I can buy bungee by the foot but I'm going to see if I can find some lightweight retaining springs to use instead. I'm thinking they'd be alot more durable. So here's design #2, using 2 pieces of pipe and just having the upper mounts welded directly to the inner pipe which is sticking out the top of the outer pipe (just an idea to save some time, still might go with the slot instead:

[nan0]

Good brainstorming guys.

Wallrat,

Another variation, but i got some 'xplaining to do!

Alright, here goes. same concept with a few changes. the movable mount is actually two sliding pieces. the inner one (green) is tied to spring 1 (low tension spring) and acts just like your original design. The outer one (red) slides on just the inner one, and has a small but high tension spring (spring 2). hold that thought.

Now take a look at the T-handle. The T-handle is rigid and connects to the (green) part of the movable mount. Lock1 and Lock2 are small tabs that will fit in a 'keyhole' slot to lock the rack open or closed. I show a view of what the 'keyhole' slot would look like.
So here's how it works -
OPEN: Line up the tab with the keyhole slot and push on the T-handle, twist to lock open. Spring 1 keeps tension so it won't rattle when open.
CLOSE: insert board and pull T-handle. As it closes spring 2 keeps tension on the board. twist the T-handle to lock it closed. During boating Spring 2 must be strong enough to not allow the board to wiggle loose or rattle.

Did I explain that well enough?

FYI, this is a view from the top. And it's probably getting too complex...

[Wallrat]

Hey! Your drawing is nicer than mine!


Ya man, makes sense to me. Not a bad idea really, but more technical and therefore time consuming. I don't see any reason why it wouldn't work. It looks like you're mainly trying to incorporate the ability to lock it in the open position and not have any rattles. Why not just leave it closed when underway? I like the thru-plate t-handle idea though...now that's slick!

[nan0]

Got MS visio here at work (and at home), works great for 2d drawings. sometime i'd be interested in trying to model it in solidworks, but i suck using that program so it'd take forever. would be sweet to see in 3d tho.

So if you wanted to lock it without a board, you'd need to relocate spring#1 to connect from the outer mount to the end of the pipe (opposite of where it's connected now). This would force the mount open, providing tension when you locked without a board. And that might be even better. when you unlocked it would automatically slide open, allowing you to easily place the board in every time.

If I only had a tower to use one of these on.....

[ShockWave]

You shouldn't need the rack to lock open, if you grab the board on the side closest to you and push away it would allow you to lift the side you're holding and then once one side is out just pull back towards you and it's out. To put board in set side furthest from you in the slots and push, then set the board down and release. it will then be locked in. This would elliminate the need for a connecting rod and alot of other work, keep it simple. I hope this makes sense. Great ideas I love DIY projects.

[Wallrat]

Probably right Shock. Most likely that would create a little more wear on the rubber upper mounts but shouldn't be too bad. Also it might depend on spring tension. I'm thinking I might make the 2nd design and move the crossbar down so that it does double duty as a handle for pulling out the upper mounts and stopping the inner tubes to keep tension on the spring.

BTW, I found some springs at Home Depot last night in with all their gate hardware. Unfortunately I had to kinda guess at which length to get and now I'm thinking that the 12" ones I bought might be a tad too long. I'll crunch the numbers and see how it turns out, at worst I'll just be going back to Home Depot tonight to exchange em for some 8" ones.

[Wallrat]

I banged out a single prototype using some of the free stock we had on hand. Just have the one arm done at this point and there aren't any bushings in it so it does rattle a bit, especially the spring. Obviously the final product will have the mounts dipped into some liquid rubber. I had to be REALLY careful test fitting the arm for the pics. But here it is, from drawing to working prototype:

[nan0]

The need for a manual locking position may depend on how strong of a spring is required. If a strong spring is required, it might be difficult to use the board to open the rack.

Wallrat,

looks great!

[thatkidchris19]

Just a suggestion. I would consider using square or rectangle stock. This would allow you to use just one arm per board by keeping it from twisting. It would keep it exta clean. "Perfection in an idea is reached not when theres nothing more to add but nothing more to take away" Im going to school for engeneering and this was in one of my books. You would also avoid having to find round bushings and making them stay in the tube by making your tolerances close and just keeping a good coat of wax on the inner tube.

[ballywho]

That seems like a good idea but then he would need something from keeping the board from sliding back and forth. With 2 mounts the board won't really be able to slide all that much.
_________________
apollo mist pics

[thatkidchris19]

my main point is to keep it simple.

[weby]

Im going to have to agree with ballywho, i think you will need to have two mounts to stop ure board from sliding about.

Looks like an awsome idea though and like thatkidchris19, it will work best if you keep everything as simple as posible.

good luck

[swilly]

The single mount might work if he puts out a "fork" type clip to hold the board at two spots instead of one at each end. Hope that makes sense.