different plywood arrived?

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jgnunn

Well-Known Member
Joined
Aug 7, 2005
Messages
175
Location
Jarrell, TX. Fly out of Taylor-T74
My order of ply arrived from Aircraft Spruce. I had orderd this:

http://www.aircraftspruce.com/catalog/wppages/finnishbirch.php 1/4 inch / 6.3mm / 5-ply

What i got was Finnish 6mm Wisa-craft 12 ply....i know that more plys is better, but 6 mm isnt a true 1/4 inch..am i being picky?

(the ply is for routered ribs)

additionally, this was half my order....now i have to ensure that the second order is ordered ASAP so as to get the same stuff to match....:pout:
 
Last edited:

Medic9204

Well-Known Member
Joined
Jan 22, 2005
Messages
46
Location
Williamsport, Pennsylvania
My opinion is 6mm is close enough...you could conceivable sand that much off in finishing. The additional plys with certainly make up for the insignificant difference.
 

Cita

New Member
Joined
Sep 24, 2005
Messages
2
The diff. between 6 mm and 1/4" is about 0.4 mm this is what....0.015"
Dont worry about it.:D
 

Falco Rob

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Joined
Apr 8, 2004
Messages
185
Location
Perth, Western Australia
If you take another look at the ACS page it states:

Finnish Birch Aircraft Plywood
(Metric)

. . . which means the product is supplied to metric dimensions.

If you measure the size of the sheets I think you'll find that they're possibly only 1200mm square which is not quite 48". (They could also be 1220mm, which is very close to 48")

ACS label the stuff as 1/4" x 48"sq to make it easy to understand for non-metric speaking customers (ie. in the US).

The fact that it's 6 ply and not 5 is also irrelevant - it's actually a bonus as it will be stronger - don't worry about it, it'll be fine.

If your next order is to ACS you can bet it will be the same, but even if you did manage to get some true 1/4" x 5 ply it's not the end of the world.

If some ribs are 0.3mm (0.012") thinner than others I doubt the difference in mass will cause you to fly in circles with one wing low, and in any case the additional ply/glue line will make up the weight difference.
 

Falco Rob

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Joined
Apr 8, 2004
Messages
185
Location
Perth, Western Australia
"Finnish Ply is supplied to ACS/Wicks in 50" sheets, they cut it down then charge for it."

I purchased my ply from the Australian distributor and the first lot I bought a few years ago was 1275mm sq (that's about 50").
Subsequent orders were supplied 1220m sq (approx 48")

I just assumed that the manufacturer, Mahogany Oy in Finland, had reduced the sheet size for some reason (shipping, maybe?).

You're right about the cost though, there was no reduction when the size went down.
 

org

Well-Known Member
Joined
Mar 14, 2004
Messages
71
Location
Castle Rock, CO
Probably if you measure the thickness of different sheets or even different sides of the same sheet, there will be more difference than that just due to manufacturing tolerances. Shouldn't be a problem.

Olen
 
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