Woodstock Imperial to Metric

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Atomic_Sheep

Well-Known Member
Hello,

Was just wondering, how much work will be involved to convert the Woodstock imperial plans into metric? Or any imperial plans for that matter. The most annoying parts would converting plywood sheets 1/16, 1/8th etc into 1.5mm and 3mm sheets because that's what is available in Australia. Would 0.087mm and 0.175mm respectively make a difference?

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Blue Chips

Well-Known Member
Speaking for myself only, .003 and .007 (rounded) would not bother me one bit.
Working with wood it is impossible to work within precision tolerances anyway, that's why a tape measure is used and I can tell you that they are out more then the .003/,007
Attention to fit, adherence to proven construction instructions, methods and quality material is what my goal would be.

TFF

Well-Known Member
In the US we have the same type of problems, opposite with things like Emarudes and Jodels. You buy tools in the way the plans are written. One error in conversion can scrap a whole airplane. Much cheaper buying \$200 in different tools than scrapping material and your time. Material wise, it will have to be made the correct size no matter how it is measured.

TFF

Well-Known Member
A lot of ply used in homebuilts may say 1/16" or such but many times it is MM made.

Blue Chips

Well-Known Member
Too add a bit additional information, tolerance variation on imperial or metric sizes of plywood will be as much or more then the differences you are asking about.

A simple conversion from inch to metric is simply multiply the plan inches * 25.4
For fractions you could make a simple list of them already converted to mm.
So if you had a piece that shows 23.5 inches just multiply that X 25.4 to get the mm, in this case 596.90 mm
say it was 23 7/16 (.4375 inches) so 23.4375 * 25.4 or 595.3125mm.

I think you will find it isn't that big a deal all things considered.

Ken

Here is a online calculator
http://www.electricscooterparts.com/conversioncalculator.html

rheuschele

Well-Known Member
My plans came in metric, so I started page by page to convert it. 10 minutes later I went a bought a metric tape measure.

Atomic_Sheep

Well-Known Member
My plans came in metric, so I started page by page to convert it. 10 minutes later I went a bought a metric tape measure.
Yer, I didn't mean to simply convert the measurements on the plan, I was referring more to the problem of substituting parts in imperial to metric.

BoKu

Pundit
HBA Supporter
Yer, I didn't mean to simply convert the measurements on the plan, I was referring more to the problem of substituting parts in imperial to metric.
If you're talking about hardware such as nuts and bolts and such, I think that you'll find that even in Australia inch-sized AN-series hardware is the defacto standard. I think even Airbus still uses it widely. At issue is that there is as yet no comprehensive metric equivalent that provides the same granularity of shank diameters and grip lengths.

For example, the AN-3 bolt has a 0.19" (4.8mm) diameter and comes in different lengths on .125" (3.17mm) increments. By using one or two AN960 washers of either the thick (.06", 1.5mm) or thin (.03", .75mm) types, it is easy to get a nice tidy bolted joint with no threads bearing in shear and with a minimum of excess thread.

Thanks, Bob K.