trying to to figure out the surface area sq.ft.

[saintrich]

I have read the post on the 720 Rule and I still don’t know how to figure out the surface area sq.ft.
I’m wanting to anodize a gun receiver for a Ruger 10/22.
The receiever is laying on a standard piece of paper.
Can anyone help?
Rich

[sswee]

Break it down in sections.
The top is 3/4" x 5" = 3.75" square. Need to insert actual dimensions.
Break the sides down to smaller squares and rectangles to figure the areas and add them all together.
Bores are figured Pi(3.14) x diameter x length.
The closer you get, the better but you don't have to be exact.
Some trace out on 1/4" square graph paper and count the squares.
If you have problems, give the dimensions and I'll help with the calculations.
Also be warned. That looks like a cast part, which means it could be difficult to anodize. Rclint use to ano Ruger 10-22 parts. I don't know if he is still on anymore but you may try to PM or email him. He's a good guy and will help if he can.
SS

[dmiom]

just to add one tiny thing to SS's advice above - its the whole surface you need - the area that counts is the wetted area that is in contact with the electrolyte. What that means is you need to include any 'inside' surfaces as well. Frequent mistake when anodising cylinders is taking the outside and forget about the inside! In this case, you need to make sure you include the area inside the slot (if its of any depth).

Also, a suggestion : looking at the bottom of that block, it has two thin sides and other material beyond the slot. You could measure those individually, but if you just look down on it, they all add up to the same surface area as the top. What you need to do for the slot is add-in the extra surface area for the vertical sides of the slots... And tiny screw holes - would ignore them. Temptation is to subtract them - in fact, because of the depth, the walls of the screw holes will either cancel out or even slightly increase the SA - so in this case would suggest you just ignore them (but you will need to make sure they're clean and don't drag-over chemicals between tanks).

Dave

[saintrich]

I found a photo of a receiver for a Ruger 10/22 that was anodized by Rclint.
I emailed him but I have no reply let.
What is PM?

[thorimmortal]

Doing a rough scale from your pics, I took some measurements to show you how the surface area lays out to the best of my knowledge, this is just a rough Idea so you can see what SS and Dave are trying to explain,
in the picture the blue area would be the surface area of one side exterior, multiply that by 2
the green would be the inside of the reciever one side also mult.x2 (if memory serves there is no tube in there its just an empty shell)
the pink is the out side circumference multiply this by the width(aprox 2")
followed by the teal that would calculate the same as the pink.
you would still need to figure the slot in the front(LxW for each surface, being that its just a machine groove not much there but still a wet area, as with any recess or hole as aforementioned by Dave) and if the rear hole if it is machined through solid stock, I cant recall what it looks like inside(Pi r2 x L)
Also where the barrel fits into the receiver another tubular surface area calculation(probably close to Pi)
These measurements are not exact but should give you an Idea of where you need to be when you actually measure the part.
Blue 12 sq in x2=24
Green 9 sq in x2=18
Pink 16 in x2"(w)=32
Teal 10 in x2"(w)=20
barrel into receiver = 3

Approximately 97 sq in +/-

Once again this is guessing on some measurements outside of being able to calculate by scale or orientation and not having the part in my hands to accurately measure it, just break down your measurements into simple shapes that you can calculate into surface area quantity.
If any one sees an issue with the way I did this or would like to add or correct information, please let me know, I don't mind constructive criticism, that's how we learn from our mistakes.

[sswee]

PM is private message.
SS