backplate specs...

[fjpatrum]

So I just got an old horsecollar off ebay and I'm going to make my own BP/W. I found some dimension information about a backplate somewhere online, probably here, but I didn't see anything about thickness. Does anyone have some thickness specs for various backplate stock? AL, or SS would be appreciated. I'll probably be using SS, but may use AL as well. I have access to some sheet metal bending tools and I'm looking forward to giving this whole process a try.

I may just make a flat "soft" backplate in the meantime, but eventually I want a metal plate, so thicknesses would be good to narrow down some of the trial and error a bit.

 

[Rich Keller]

I can not help you with thickness of backplates but I would be very interested in seeing your backplate specs if you are willing to share them. Also I would like to know more about your soft backplate idea. Is it something like a Miller harness?

 

[Ed Palma]

Perhaps you saw links to Huw Porter's H - Plate

3mm in 5052 aluminum. He posts the other dimensions as well. Good site.

 

[Rich Keller]

I do not see measurements on the fold patterns on the right. I am trying to figure out if I can use this plate with twin 30s with a diameter of 4.87" connected to a manifold that is 5.5" at the centerline of the dipping tubes.

 

[Ed Palma]

Oh, the H-plate was designed for singles. The plate is bent in such a fashion that a STA is not necessary.

(I just re-checked the design - there're are values for a conventional twinset plate as well)

The measurements can be deduced from the given values above. (get the inverse functions of sine and cosine. Values for the various hypotenuse, adjacents, and opposites are given)

 

[Tortuga68]

Ed: According to the plan you kindly posted, it can be bent for a twin set as well

Rich: The green lines on the top half of the plate are for the twin design & the angles are on the upper cross-section diagram at the right. Is there something else you need?

 

[Rich Keller]

Ed: According to the plan you kindly posted, it can be bent for a twin set as well

Rich: The green lines on the top half of the plate are for the twin design & the angles are on the upper cross-section diagram at the right. Is there something else you need?

I saw that the bend patterns on the side showed both types but there are no measurements as for how high the bends rise above the flat part of the plate. What I am trying to determine is if the ridge in the double plate is too wide and too high to allow a twin set of 30 cu/ft tanks with a diameter of 4.87", set 5.5" apart on their centerline to fit over that ridge and still come to rest against the flat part of the plate. I want to use the plate not only as a backpack but also have it do the job of twin tank bands.

 

[Tortuga68]

I saw that the bend patterns on the side showed both types but there are no measurements as for how high the bends rise above the flat part of the plate...

No, but the angles are there - if you have a ruler and a protractor, you can draw the profile in 1:1 scale and go from there (easier than doing the match IMO)

 

[Ed Palma]

...I want to use the plate not only as a backpack but also have it do the job of twin tank bands.

Okay, now I'm curious Could you give us a rough sketch of what you had in mind here?

One thought that comes to mind is that if you're going to practically attach the plate to your tanks to keep it steady, you might as well just make a set of bands and attach a harness to the bands old-school style - therefore no need for the plate! (of course this assumes that you won't be using a wing)

 

[fjpatrum]

Doc Ed, that's not the design I found, though now I can't seem to find the file for the one I did find. Thanks for posting that one. I ended up buying a Salvo Plate and using that to "reform" my PVC plate which originally only had a simple bends to form a center flat section for the tank.

RichKeller, the soft plate would be something along the lines of a piece of thin plastic sheet, maybe a couple mm thick, wrapped in some fabric a-la transpac style rig. I haven't done that at this point as I like the weight of my steel plate. No weight belt is a wonderful thing.