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Imperial vs Metric

Old 01-01-2011, 02:57 AM
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vasek
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Default Imperial vs Metric

Are Metric and Imperial balsa sizes cut the same size (just re-named)? or are the actual sizes different?

I'm asking because if i get a short kit meant for imperial balsa stringers and sheeting, how would mm sized stringers/ balsa sheets fit?

I'm sure someone has done this before, so any help would be great.

thanks
Old 01-01-2011, 03:11 AM
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perttime
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Default RE: Imperial vs Metric

As far as I can tell 1/16" is close enough to 1.5mm and 1/8" is close enough to 3mm.... the difference may be 0.1mm but I am not convinced you can cut and store balsa more accurately than that anyway.
Old 01-02-2011, 07:50 AM
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Default RE: Imperial vs Metric


ORIGINAL: perttime

As far as I can tell 1/16" is close enough to 1.5mm and 1/8" is close enough to 3mm.... the difference may be 0.1mm but I am not convinced you can cut and store balsa more accurately than that anyway.
Anthing wrong with quoting the differences ?

1/16 inch is 1.5875 mm
1/8 inch is 3.1750 mm

I have measured some stringers and sheeting to higher accuracy than 3.5 thou and 7 thou.

One thou is 1/1000 of an inch.

The precison of the balsa depends on the manufacturer tolerances and we and the retailer usually do not know the manufacturer tolerances.

The buyer can bring a caliper and measure it . .
If ordered by mail or internet ask if the material is manufactured in inches or in metric before ordering.
The retailer should be able to make some measurements.

Zor
.
Edit ___

Just measured a new sheet of semi-hard balsa labelled 3/16 x 2 x 36 inches.
The thickness varies from min of 0.187 to max of 0.189 inch .
So this sheet varies by 0.002 inch ( 0.0508 mm )
3/16 inch is 0.1875 inch

This is pretty good accuracy so if the manufacturer use metric or imperial (inches) could make an appreciable difference.

End
Old 01-02-2011, 08:08 AM
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Daryl_y
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Default RE: Imperial vs Metric

1 mm = .03937" or 1" = 25.4 mm. divide or multiply as required.

for example .500" is 12.7mm (.500 x .03937) or 16 mm is .0629" (16 / 25.4)
Old 01-02-2011, 08:22 AM
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Default RE: Imperial vs Metric


ORIGINAL: Daryl_y

1 mm = .03937" or 1" = 25.4 mm. divide or multiply as required.

for example .500" is 12.7mm (.500 x .03937) or 16 mm is .0629" (16 / 25.4)
16 mm is 0.629921 inch

Ya ___the usual trouble maker.

Zor

Old 01-02-2011, 10:33 AM
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perttime
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Default RE: Imperial vs Metric


ORIGINAL: Zor

I have measured some stringers and sheeting to higher accuracy than 3.5 thou and 7 thou.

One thou is 1/1000 of an inch.
...

Edit _ _ _

Just measured a new sheet of semi-hard balsa labelled 3/16 x 2 x 36 inches.
The thickness varies from min of 0.187 to max of 0.189 inch .
So this sheet varies by 0.002 inch ( 0.0508 mm )
3/16 inch is 0.1875 inch
Sure: you can measure to that kind of accuracy. But can you cut to that accuracy?

I bet not many can. People cut until they are pretty close and then sand the last 0.05 to 0.2 mm to fit, regardless of whether the wood is just right or some fraction of inch or mm off.
Old 01-02-2011, 02:07 PM
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Default RE: Imperial vs Metric


ORIGINAL: perttime

ORIGINAL: Zor

I have measured some stringers and sheeting to higher accuracy than 3.5 thou and 7 thou.

One thou is 1/1000 of an inch.
...

Edit ___

Just measured a new sheet of semi-hard balsa labelled 3/16 x 2 x 36 inches.
The thickness varies from min of 0.187 to max of 0.189 inch .
So this sheet varies by 0.002 inch ( 0.0508 mm )
3/16 inch is 0.1875 inch
perttime
Sure: you can measure to that kind of accuracy. But can you cut to that accuracy?

I bet not many can. People cut until they are pretty close and then sand the last 0.05 to 0.2 mm to fit, regardless of whether the wood is just right or some fraction of inch or mm off.
We do not have to cut to that accuracy.
In fact we should not.

We should not cut "pretty close" . . . we should cut a bit longer.

As you meant I think; we measure, cut a bit longer and sand to fit.

We are saying the same thing so I do not know why the question can you cut to that accuracy?

The sanding is part of the cutting process to fit so YES I can cut to that accuracy and YOU can also.

I thought it was evident that my original posting was referring to thickness of stringers and sheets.
In fact I wrote "the thickness varies"

Have a nice 2011.

Zor

Corrected formatting.

Old 01-02-2011, 04:51 PM
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Default RE: Imperial vs Metric


ORIGINAL: vasek

Are Metric and Imperial balsa sizes cut the same size (just re-named)? or are the actual sizes different?

I'm asking because if i get a short kit meant for imperial balsa stringers and sheeting, how would mm sized stringers/ balsa sheets fit?
Vasek,

I have a Curare .60-powered classic pattern ship short kit. The plans are in metric, but I bought the short kit from Eureka Aircraft Co., a U.S. company, and the wood supplied in the kit is milled in U.S. Customary Units (Imperial). Most of the wood in the short kit is *really close* to their metric counterpart. When I laid-out the short kit wood on the plan sheet, I really couldn't tell a different between 10 X 10 mm triangular stock balsa and the supplied 3/8" triangular stock balsa. Works for me. Nor do I plan to sand or shape any part of this sleek machine to within .01-whatever between the plans and the U.S. Customary Unit wood that I can readily get.I checked two balsa suppliers here and neither even mention metric sizes, so I have to live with what is available.

Not sure what model you're looking to get, but I just can't imagine things being a big deal *in most cases* between metric sizes and the closest Imperial sizes. You did write that your concern are the stringers and sheeting. Sheeting should not be a problem as it really doesn't need to fit between anything. Although, stringers (depending on the plans/design) fit into recesses in formers, and if the recesses are cut in metric tolerances and the stringer material Imperial, that *may* present a problem. I'd opt for the next larger Imperial stringer sized material and open the former recesses.
Old 01-02-2011, 05:10 PM
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Zor
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Default RE: Imperial vs Metric

Vasek,

Since 1/16" is larger than 1.5 mm and 1/8" is larger than 3 mm there is no need to go to the next larger Imperial stringer size.

Any notches in formers or wing ribs can just be touched up a bit if the notches happen to be metric and you can get only Imperial stringers.

Zor
Old 01-02-2011, 05:37 PM
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Default RE: Imperial vs Metric


ORIGINAL: Zor

Vasek,

Since 1/16" is larger than 1.5 mm and 1/8" is larger than 3 mm there is no need to go to the next larger Imperial stringer size.

Any notches in formers or wing ribs can just be touched up a bit if the notches happen to be metric and you can get only Imperial stringers.

Zor
Vasek DID NOT mention any stringer sizes as of yet, or IF he can get ONLY Imperial or ONLY metric wood...

How about you wait until the original poster answers until you (always) try to upstage someone else...
Old 01-02-2011, 11:56 PM
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Default RE: Imperial vs Metric

Thee is only four possibilities.

1 Metric notches with metric stringers; no problem.
2 Metric notches with Imperial stringers; touch up the notches that are slightly smaller.
3 Imperialnotches with imperial stringers; no problem.
4 Imperial nothces with metric stringers; The fit could be a bit loose. See ideas below.

Many solutions can be applied.
Use next larger size metric stringers and adjust the notches. That makes the structure stronger and heavier.
Use shimming around three faces of the stringers. Soak with thin CA glue then fillet with aliphatic.
Use thick wood glue that fill the gaps.
Use the fillet gluing technique.

I doubt thatthe same material would be labeled in Imperial somewhere and Metric somewhere else.
If we look for example at material in the 1/4" dimensionwhich is 6.35 mm, the difference becomes 0.01378 inch; nearly 14 thou or 0.350 mm .

It is doubtful that 1/4 inch material would be labelled 6 mm or that 6 mm material would be labelled 1/4 inch.

As I first suggested, inquiry or measure and know what to expect.

There is no need to go to larger imperial stringers when they are already larger .

Zor


Old 01-03-2011, 01:37 AM
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vasek
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Default RE: Imperial vs Metric

Thanks EJ, that's the kind of info i'm after!

I do have the option to order balsa from the UK (that should be Imperial) but i'll try the metric stuff first.

I'm looking to get a Super Kaos shortkit:
http://www.eurekaaircraft.com/plan_kits/kaos.htm

BTW don't worry about Zor. He's kind of a RCU clown... a annoying clown to be precise

Old 01-03-2011, 07:15 AM
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LesUyeda
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Default RE: Imperial vs Metric

" YES I can cut to that accuracy and YOU can also. "

And five minutes later it WILL be out of that accuracy. Wood is very much like rubber; continually changing in shape and size. In my younger days, I built many pieces of furniture and the like for family members.

Les
Old 01-03-2011, 07:24 AM
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vasek
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Default RE: Imperial vs Metric

FMI can anyone suggest a balsa supplier in the UK?
Old 01-03-2011, 07:29 AM
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perttime
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Default RE: Imperial vs Metric

I have to say that partly I agree with Zor too: in some sizes the difference is enough to really make a difference, especially if one side of the joint is already cut. You can usually make a slot larger but making it smaller takes more effort.
Old 01-03-2011, 08:24 AM
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Default RE: Imperial vs Metric


ORIGINAL: vasek

Thanks EJ, that's the kind of info i'm after!

I do have the option to order balsa from the UK (that should be Imperial) but i'll try the metric stuff first.

I'm looking to get a Super Kaos shortkit:
http://www.eurekaaircraft.com/plan_kits/kaos.htm

BTW don't worry about Zor. He's kind of a RCU clown... a annoying clown to be precise

Vasek,

The supplier of the Super Kaos shortkit being in the USA would likely cut the notches in imperial dimensions (inches and not milimeters) .

You are of course free to "try the metric stuff first for the stringers since it seem tomakebetter sense to you.I suggested some solutions to the poor loose fit thus existing (created).

We do not all think the sameway. Some fellows hereare "annoying clowns" ..... remember ?,

You arealso free in the event of having metric notches, to get the nextlarger imperial dimensionstringers since the imperial dimension stringers arealready larger then the metric notches would be. That did not come as a suggestion from the clown ..... remember ?

You are also free to do things the way it makes sense to you.

I still do not think that the same material of the same dimensions could be or would be labelled in inches somewhere and in metric somewhere else.

My good sense is likely to be different then yours.
Iwould not have considered asking the question.
Of course "clowns" do not have the same good thinking.

Enjoy your project and put the clowns on "ignore" if they do not make sense to you.

Zor

Old 01-03-2011, 09:46 AM
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Default RE: Imperial vs Metric


ORIGINAL: vasek

Thanks EJ, that's the kind of info i'm after!

I do have the option to order balsa from the UK (that should be Imperial) but i'll try the metric stuff first.

I'm looking to get a Super Kaos shortkit:
http://www.eurekaaircraft.com/plan_kits/kaos.htm
The 60, 90, or Jr.?

I'm impressed with Eureka's quality. Not sure if you've considered one of their full kits or not. I see that all three versions come with the fuselage sides. This being the case, the short kit may be shipped in a box long enough to accommodate 36" lengths of sheet and/or sticks of whatever balsa you need. Email Don at Eureka, I'm sure that he'll work with you.

Les is right-on - Wood moves. It's silly to argue .00X (X = whatever!) tolerances in respect to wood. The subtle change in a day's atmospheric humidity will cause the wood to expand/contract anyway.

I hope that you got some insight on your original question.

BTW don't worry about Zor. He's kind of a RCU clown... a annoying clown to be precise
Don't worry, unfortunately, I'm VERY familiar with this character (as well as the moderators).

Annoying? Hey, like the saying goes, "be good, or be good at it..."
Old 01-03-2011, 07:11 PM
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Default RE: Imperial vs Metric


ORIGINAL: vasek

FMI can anyone suggest a balsa supplier in the UK?
I am glad to see hat you have changed your mind and now seek imperial dimensioned balsa to fit properly in an American short kit.

It makes more sense than what had been suggested to you previously.

As well as asking here for UK retailers make a search.

Any UK fellows out there to help our friend Vasek ?

Zor
Old 01-04-2011, 01:08 AM
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vasek
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Default RE: Imperial vs Metric


ORIGINAL: EJWash1

The 60, 90, or Jr.?

I'm impressed with Eureka's quality. Not sure if you've considered one of their full kits or not. I see that all three versions come with the fuselage sides. This being the case, the short kit may be shipped in a box long enough to accommodate 36'' lengths of sheet and/or sticks of whatever balsa you need. Email Don at Eureka, I'm sure that he'll work with you.
I want the Super Kaos 60. One of the planes I admired when I started RC flying & never got around to build it.[:@]

You're right EJ, it never occured to me to ask a shipping quote to EU for the whole kit (forgot about the sides). With the steeper US shipping prices I didn't even considered it but i'll see. I also have the option sourcing the rest of the balsa from UK and if the shipping is too steep i could even not bother with shipping the sides and cut them here.

Thanks again,
V.

Thanks again,
Old 01-04-2011, 10:30 AM
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Default RE: Imperial vs Metric

I owned a Super Kaos back in the late 1970s. I was flying a Sig Kommander, but the really "hot" pilots were flying the Kaos. I was building a sport biplane at the time and did not want to abandon it to begin building a Kaos, so I when one of the club members put his up for sale, I grabbed it (less radio & engine). Besides a couple of pattern ships I've owned, the Kaos is THE most enjoyable and honest sport planes I've flown. It rides on rails.

Since you found Eureka Aircraft Co., I suppose you came across there guys:

http://www.bridiairplanes.com/

There is at least one other options for you to get a Kaos going - building from plans.
RCM Plans (http://www.rcmplans.com/) offers the plans for the Kaos, Super Kaos, and the Super Kaos Jr (52"). The Super kaos is the Cadillac of the series. I have a copy of the Super Kaos plans in my "stash". Not sure that I'll ever build one, but at least the option is there in case I get a wild hair...

I don't know yourbuilding skill level, but looking at the plans, the most "difficult" (if you want to call it that) part of the build would be cutting the ribs and building the wing. Its a double-tapered wing design, and the ribs in each panel get smaller in chord and camber from root to tip. A metal rod type wing jig would make building the panels easy. The fuselage and tail group are all simple sheet an stick construction without any "fancy" wood cutting or shaping involved.
Old 01-09-2011, 11:00 AM
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Default RE: Imperial vs Metric


ORIGINAL: vasek

Are Metric and Imperial balsa sizes cut the same size (just re-named)? or are the actual sizes different?

I'm asking because if i get a short kit meant for imperial balsa stringers and sheeting, how would mm sized stringers/ balsa sheets fit?

I'm sure someone has done this before, so any help would be great.

thanks
Metric or Imperial..?? The answer is easy:

When you are young and have good eyesight, you use Metric as the graduations and numbers on rulers are small and fine and you want to impress, when you're becoming old buggers with not so good eyesight like us, you go for Imperial as the numbers on the rulers are larger and easier to read - no need for accuracy, you can build on your experience.......

Cheers

Bundu
Old 01-20-2011, 12:29 AM
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Default RE: Imperial vs Metric


ORIGINAL: Bundubasher


ORIGINAL: vasek

Are Metric and Imperial balsa sizes cut the same size (just re-named)? or are the actual sizes different?

I'm asking because if i get a short kit meant for imperial balsa stringers and sheeting, how would mm sized stringers/ balsa sheets fit?

I'm sure someone has done this before, so any help would be great.

thanks
Metric or Imperial..?? The answer is easy:

When you are young and have good eyesight, you use Metric as the graduations and numbers on rulers are small and fine and you want to impress, when you're becoming old buggers with not so good eyesight like us, you go for Imperial as the numbers on the rulers are larger and easier to read - no need for accuracy, you can build on your experience.......

Cheers

Bundu

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