Date:	Mon, 30 Aug 1993 23:11:03 -1000
From:	salanne@convex.csc.FI (Simo Salanne)
Message-Id: <1993Aug31.091103.555@nic.funet.fi>
Organization: Finnish Academic and Research Network Project - FUNET
Subject: Drawing and cutting arcs (possibly a repost?)


I tried to post this already, but it didn't appear on my news
server. I am sorry if it's unnecessary repost.


"Jaco" dividers (pair of compasses)
-----------------------------------

Curved shapes are very popular in kites today. Not only 
for decorative purposes, but e.g. in trailing edge of 
single or dual line deltas to reduce unwanted flutter. 

One technique to draw wide arcs is to use a bent spar as 
ruler. This works very well unless a certain radius of 
curve is wanted. A calculator and some knowledge of 
geometry is needed to determine the amount of bend 
corresponding to the wanted radius. 

More straightforward way is to use dividers.

Because dividers of useful size ( > 1 meter) are not 
available, or are very expensive and clumsy, we have to 
make one by our selves. 

The key components are the same we use to build sport 
kites: leading edge connectors and a carbon spar. I used 
T-shaped Jaco Pro connectors - because they are good, and 
I had them on the shelf. I inserted a nail in one of the 
connectors. Actually I glued a nail inside of a piece of 
carbon spar, which fits nicely in the connector. To the 
other connector I put a pencil, I had to use sand paper 
to make it fit. 

Now, take a full lenght of spar, put the connectors with 
nail and pencil on it, adjust the distance and start 
drawing your templates. The nail should keep one end in 
place when you draw your arcs. 

Some additional tips.

I use heavy metal pieces to keep templates, fabrics etc. 
in place when I work on them. (Actually they are old, 
damaged loudspeakers, tweeters. The cone is removed). I 
drilled a hole for the nail in one of the weigths, now 
the center of the arc can be outside of the template 
material. 

I also made a knife acessory for the Jaco dividers; I cut 
a slot in a connector through one wall, inserted a piece 
of Stanley cutter blades, tightened with a cable tie in 
place. With the knife I can cut curved panels from fabric 
directly, without a template:-)) 

Hot cutting accessory is still unsolved.

Disclaimer: I am just a customer of Jaco Engineering...

Smooth Winds
Simo.Salanne@csc.fi

uuencoded GIF-picture of dividers follows:

begin 755 jacodiv.gif
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M3=140#)EAIP><?;4>#-T)T_5PP]<'3"T*0.6>KTZ?(IA)10?:$692F5*U1
MMP;PRH#JUZM9K7(5.];LRI-CSR)E^Q1L/ZQ:U]9]>]>!2+H(]E8M2[9O8+P+
M_$XE:WCM29")XP)>')AQ9,24\_[CJ]:GY;"#-R?VW+FMZ,V$2U8>71CR7<<R
MX7J47->O[-#^, /F3HS:K5\"6/=6E.N;M:M88LFGMJP\>6NJ6:=^Q<T;M33
M>Z^.+MCRS*7/A[O6J_KX=\[*7T]VF[:[/I[9V?K&SEW[<Z^\X6/W?AA]9IV-
MQ^?_Y0^;9.;IY]\^: DV((+SN?< ?=UU!=6"F45HVFP2!CB8@!<BEAY7'7ZH
MX49U,"5B+"26N,IG*.(BW(HNO@ACC#+.2&.--MZ(8XXZ[LACCS[^"&200@Y)
M9)&'HEDDDHNR6233CX)99123DEEE59>B6666F[)99=>?@EFF&*.26:99IZ)
M9IIJKLEFFVZ^"6><<LY9A'HWV$FG#'C6L.>.UED716B RI==:;O]Y-Z@,UY
M4Z-?.=KG$J]!2NFC?57*J*69;NJHI9IVFF-5F((ZQ:2?7NHIJ9R>>MI\2      J
MYZNLDBJJ9G*6M9*H\Z*:J^KAKIK@I$:@>BC>^V*:[#*_Y[JZ:^A(@I3H\,2
MFQ.D]Q7Z'[)_8CNMC-WF:<:WX)(A[KA8.(=NNNJN>Z .[+X+;[SRROMEN7G8
MJR2^=^B;)+\C>NDO'0$;.; <!1-Y\!L)"[FP&PT#^? :$?LXL1H5\W@Q&AGK
MN'$9'>/X,;GU+A*RC26+<3*-*7^QLK>,M!PCSS(#"/-6MB\(L[G@JGS  V+
M^+,500-,L]WPTTHJ<V.30I3K=4M)=,KTOU(/ NS35^Y*W;BCH1O#UU58'
MZAS895?2H@4,^J'U'&E7\#8A:X<0M]MRMUUAUB.-#0S>_B=Q;R"#TYXX88?
MCGCBBB_.>.../PYYY/'2('GEEO]?CGGFFF_.>>>>UWW"YZ*/3GKIII^.>N>4
MI\YZZZZ_#GOLEZ\N>^VVWXY[[J@S<3+?O_2.R.!<TVN@\,D1?XEZOHNCO"K-
MYQR6\]      YCTU5./D_798Z]K*L^C^/TIX0,]/2KC;W0^*>EGM+XH[5_T/BCQ
M5S2_)_5/=#\G^4>TOR;]/_0_3 2P(0.T1 $7<D!*)# A"Y1$ P_R0$A$L" 3
M=$0!W+!EY6O1!F46J\XN$  =! @(TQ$"6L3PE*<<"XI5\+V?="]\40?C.4
M7PWI=T/[Y1!_.]1?#_GW0_\8!#& 1"7A$ R81@4M48!,9^$0'1A&"4Y1@
M0.000000E+00X10O_JLM                                                                         M1][CX12]^$'QAU!ZMR#=&[Y41A&DTWQK1*"M6Y.I<Y3C
M&]W1_'08Z@D^$9.=A'&2[O''.SXR"7<2L,.?]Q)(\.!KT3" EHC..0C
M_G0?22I0[)8Y'2RE2I$+FM5G 1;+SS9/5(^LAB;@@NL7KG)4TY+E<QBAK-X
ME2RU6;(/PZ)E*8_ARU&J+1B]I-2Q0JD,!E6K6<5"9H.&$:E;,>J7QDC9+@-Q
M33V^A)7K !XW*9)-083S&>/$YNQXL3MSJ7.=[&RG.]\)SWC*<Y[TK*<][XG/
M?.ISG_SLIS__"=" "G2@!"VH00^*T(0J=*$,;:A#'PK1B$IT)*(4K:A0K1
>C&ITHQSMJ$<_"M*0BG2D)"VI24^*TI2J=!@[
 
end



 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =


Date:	Tue, 31 Aug 1993 01:48:16 -1000
From:	mtvahb@rivm.nl (Aldrik Bakema)
Message-Id: <CCMGsH.1yu@rivm.nl>
Organization: Rijksinstituut voor Volksgezondheid en Milieuhygiene,Bilthoven,NL
Subject: Re: Drawing and cutting arcs (possibly a repost?)

Simo Salanne (salanne@convex.csc.FI) wrote:


: "Jaco" dividers (pair of compasses)
: -----------------------------------
:[lots of complicated stuff deleted]  
: end

I may be missing something here, but isn't it much easier to use one nail
with a line attached to it that has a loop at the end?
You can use the loop to fit a pencil, knife or anything else in.
It 's simple and it works for me.

Aldrik Bakema
mtvahb@rivm.nl

--


 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =


Date:	Tue, 31 Aug 1993 05:59:13 -1000
From:	salanne@convex.csc.FI (Simo Salanne)
Message-Id: <1993Aug31.155913.25313@nic.funet.fi>
Organization: Finnish Academic and Research Network Project - FUNET
Subject: Re: Drawing and cutting arcs (possibly a repost?)

In <CCMGsH.1yu@rivm.nl> mtvahb@rivm.nl (Aldrik Bakema) writes:

>Simo Salanne (salanne@convex.csc.FI) wrote:

>: "Jaco" dividers (pair of compasses)
>: -----------------------------------
>:[lots of complicated stuff deleted]  
           ?????------)
>: end

>I may be missing something here, but isn't it much easier to use one nail
>with a line attached to it that has a loop at the end?
>You can use the loop to fit a pencil, knife or anything else in.
>It 's simple and it works for me.

Have you cut ripstop that way?

I have used nail-line-pencil, too. "Jaco" dividers gives more
consistent results. With a line it's hard to get +/- 1 mm
accuracy. 1 meter of 6 mm carbon spar is a lot less flexible
and compressible (sp?) than 1 meter of line - regardless of 
line's breaking strength.

Smooth Arcs
Simo





 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =