DIY backplate and harness

[JessH]

I hadn't thought about only moving the diagonal slots but I really like that idea. The only problem I can see with this is that the harness will then cover the cam band slots. Make the cam band slots thick enough to pass both the harness webbing and the cam band through it and that should move the harness webbing completely out of the way. It also will no longer move a single tank farther away from your body.

Hey Tobin, I hope your still listening ;-)


Another thing to consider would be to bend the center channel inward like on the mark meadows plate so that it acts as a built in STA. Then you don't even need an integrated soft STA like some systems use. If you do it right it should still work fine with doubles or an STA if you decide to go that way.

~Jess

 

[JessH]

I just thought of something else you might want to consider. On Hammerheads backplates they bend the bottom corners away from the diver slightly to keep it from digging into your back. You can't bend it much or it might get in the way of double tanks, but it is a nice little detail.

~Jess

 

[jcadwell]

Thanks for the replies. I was in the process of widening the slots when you suggested it. Doubling up the harness and cam band was one of the things I had in mind originally.

I relaxed the angles on the bends, so the middle section is now only about 1/2 in higher than the plate. I thought about adding more bends in the middle to emulate an STA, but I'm not sure the aluminum will take any sharp bends without cracking. I tried bending various alloys on the bending brake. 6061 won't take sharp bends (>45 ish). 5052 is better, but I don't want to push it. I don't want to anneal anything just to bend it.

The easy solution is to put one more bend right down the middle of the plate, so I end up with a V to cradle the tank. But that leaves the bolt heads resting on an uneven surface. I could always forgo the bolts, but I like having them. Less hassle repositioning the wing when I set up.

Here is the latest version...

 

[cool_hardware52]

I relaxed the angles on the bends, so the middle section is now only about 1/2 in higher than the plate. I thought about adding more bends in the middle to emulate an STA, but I'm not sure the aluminum will take any sharp bends without cracking. I tried bending various alloys on the bending brake. 6061 won't take sharp bends (>45 ish). 5052 is better, but I don't want to push it. I don't want to anneal anything just to bend it.

To avoid cracking the material pay attention to the temper of the sheet, and consider the radius of the bend. You shouldn't have to anneal anything if you start with a softer temper like H16. If you have the brake tooling available, punches with a larger radius will be less likely to crack the sheet. Wide bottom dies, and large radius punches are a big help.

The easy solution is to put one more bend right down the middle of the plate, so I end up with a V to cradle the tank. But that leaves the bolt heads resting on an uneven surface. I could always forgo the bolts, but I like having them. Less hassle repositioning the wing when I set up.

If you don't bolt your wing onto your plate you shouldn't need any extra bends.

With a flat style plate you probably don't need any extra "corner kicks" at the bottom of the plate. You might consider a larger radius at the bottom corner.

Good luck,


Tobin

 

[Mo2vation]

This thread is like motorhead p0rn.

 

[JessH]

You are probably right about the extra bends, and since I have thought about it some more I have actually decided that I like it without them better. I personally prefer using an STA even to solid STAless designs, and now that I have a lightweight aluminum STA there is really no reason for me to ever not want to use one. It should be rather simple for you to make up a very lightweight aluminum STA as well.

It looks like with your newest design you will still have the harness webbing passing over the upper bolt holes. If you add back a little bit of material you could move the diagonal slots down to the second set of slots so that the webbing is out of the way of the bolt holes.

~Jess

 

[Packhorse]

I think you may find that running both the tank straps and harness thru the same slots may be a bit of a pain especialy if you need to remove and replace the straps for changing between doubles and a single.
Also what are the extra wider slots at the bottom for with the second design?

 

[jcadwell]

I do have large radius tooling for the brake. I'm starting with 5052 H-32. I'd like to bolt the wing to the plate, so I need to do something; Either extra bends or an STA that accomadates that. Probably the STA route, and make one that adds the least amount of height.

I see that the strap covers the bolt holes. I tried moving things around, but didn't find a place I liked. Mostly aesthetic.

 

[jcadwell]

The extra wide slots give me the option to double the harness and cam band, so I would have the possibility of four cam band locations. Might be nice for a tall single.

 

[cool_hardware52]

I do have large radius tooling for the brake.

Very cool, nothing like a well equipped press brake. One of my favorite tools, too bad the tooling is so expensive. I'd love to have BIG brake, but I running out of room. One of my close friends is a old time race car fabricator, the things he does with a brake are pretty cool.

I'm starting with 5052 H-32.

H-32 should bend pretty well. I don't have them handy, but there are min bend radius charts.

I'd like to bolt the wing to the plate, so I need to do something.

There is no functional need to bolt the wing onto the plate. Do as you like, but it just makes cleanup more work, and having your wing in close proximity to the plate increases the chances of a pinch flat.

If you pick a wing before you build you can position the camband slots in the plate to be at the "extremes" of the slots in the wing. This way the cambands will keep the wing correctly positioned.

I see that the strap covers the bolt holes. I tried moving things around, but didn't find a place I liked. Mostly aesthetic.

If you lower the "45" slots at the top you can miss the bolt holes, but melting a hole through the harness is no biggie either.

You really don't need the upper camband slots in your current design, the lower two sets are plenty. It's not uncommon for people using conventional STA's to comment that they can get their tank positioned as low as they'd like. Even with a "tall single" you are going to want the valve where you can reach it.

Good Luck,

Tobin