Imperial to Metric Conversion

[DavidKP]

I went to the local model shop in Switzerland today with the Chapter One wood list. No problem with getting 3mm balsa sheet for 1/8th inch and 1.5mm for 1/16. but what about 3/16th? I can only get 4mm or 5mm not 4.5, I suppose 4mm will be fine for the tailplane and rudder. But the plan calls for 3/8th square leading edge which calculates to 9.5mm. I can only get 8mm square or 12mm. Does anybody think it it would be a problem if I slim down the front of the wing rib template by a millimetre or should I just accept that I will have to get the 12mm square and sand a lot more off?

[sticky fingers]

David, you shouldnt have too much problemss if all timber is metric. Buy yourself a balsa stripper and make up your own stripwood cheaper, and you can make things to fit without too much hassle.

Dave

[Dave Hopkin]

You can also laminate up thinner strips to make up certain sizes, like for the 9.5mm leading edge, using a balsa stripper cut a 9.5mm wide strip from 6mm and a 9.5mm wide from 3mm and laminate them together, it will be close enough

[DavidKP]

Thanks for the suggestions. I am just getting back into the hobby and I have never used one of those balsa strippers before, I will get one and let you know how I get on with my leading edge.

[kc]

Use 5mm rather than 4mm for the tailplane & fin

[kc]

Having looked up the Chapter One plan I see the LE construction - a 3/8 sq stuck on the front of the ribs and then shaped. An alternative and probably better way is the 'false LE' idea used by Philip Kent & lots of other designs.

Basically a 3mm or 1/8 sheet is first stuck to the ribs then the 1/16 top sheeting overlaps this. Later on another layer or two of 3mm / 1/8 is added and shaped. These can be a bit narrower to save sanding or planing saves money and makes a stronger job.  It avoids the use of imperial sizes too in this instance. Strips like this can be cut with just a scalpel and straight edge.

My picture shows a typical false LE from another thicker wing, but the same principle. Ask again if this is not clear.

Edited By kc on 27/08/2016 18:35:43

[Martin McIntosh]

Are you sure that the local balsa really is metric or have they just done a rough conversion? Most timber is still cut in imperial sizes, just as props. on the continent are in inches of diameter and pitch.

You could always simply order from Balsa Cabin etc in the UK to get the correct sizes.

[DavidKP]

kc, OK it will be 5mm for the tail end, and I like that idea for the 'false LE', I will definately incorporate that into the build.

Martin, I must admit that I did not check the size, I was just going by the descriptions next to each rack, but I have just checked the sheets I bought, they are definately 1m long and 100mm wide, not 4inches.

The problem with ordering from the UK is the delivery charges, I would like to have ordered the CNC wood pack for Chapter One, GBP 55.25 seemed like a good price, but the delivery charge was another 74.99

[Martin McIntosh]

I am surprised that someone could even think of those delivery costs, even HK Europe only charge about £9 for 2 kg. I recently sent a small package to Corfu for £3.50.

I may well be wrong about the continental wood sizes.

[Lorenz Mueller]

Living in Switzerland myself, I can only confirm the outrageous shipping charges. I was interested in some Tony Nijhuis woodpacks, but interest quickly waned upon discovering the shipping charges were much higher than the cost of the wood every time! The PSS Skyhawk in comparison was quite reasonable - about £30 for kit costs of £55.

As for the leading edge, you should be able to get a 10mm plank or even 10x10mm strips quite easily, even Coop Bau&Hobby carries both.

Lorenz

[Peter Miller]

That leading edge system is the one that I have been using for years and years.

[Ernie]

Hi David, Wood sizes are not too difficult, especially with a decent wood stripper.

But beware, beware Thread sizes.

Its not always easy to know if you are dealing with metric or imperial. I strongly recommend that you bin all imperial stuff, and invest in a whole bundle of everything metric

ernie

[Jonathan M]

Re stripping balsa, I do this for my indoor scale rubber builds, for which I prefer to use a scalpel and straight edge.

If you do use a balsa stripper (or just a straight edge) be certain to cut lightly over several passes, else the grain direction could grab the scalpel tip and pull it out of true.

[Robert Whisnant]

Why don't you just use an online converter?

 

Edited January 29 by Martin Harris - Moderator
Link removed as from a new poster.

[David Ovenden]

Model shops (with websites) here in France list 10mm Square balsa so it is available. Maybe mail order?

[Futura57]

I've contemplated using a balsa stripper to save money, but she kept getting splinters when she undressed. But seriously, can someone recommend one because many folks have told me some are not up to the job? But wait, a new topic, or perhaps I should go search for an old topic. Sorry to interject. 

[Andy Stephenson]

I tried the blade type but the problem is that as soon as the cut goes wrong as it quite often does due to the blade wandering in the grain, you can't use that edge as a reference any longer. I have used a scroll saw but now I use a band saw or proxxon mini table saw. These are expensive options but so is balsa these days.

[GrumpyGnome]

As the thread is 7 years old, I'd assume the OP found a solution 🙂

 

Although the conversation about strippers is useful.....

[kc]

The SLEC stripper with a long aluminium channel works well.   For thicker balsa a shallow cut followed by deeper cuts is the best way.   Cutting spars might be best done with a circular saw as you probably need hard balsa.  

[Tom Gaskin 1]

+1 for the SLEC balsa stripper. Mine is about 45 years old now and always comes out to produce the stripwood/depron - as KC says, use many light strokes (and a sharp blade) to make the cut.

 

Tom