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(transferred posts): formula
PostPosted: Mon Jan 26, 2009 11:07 pm  Reply with quote
knot_tyer
 
Joined: 25 Apr 2008
Posts: 1139



Hi Dan,

Thanks so much for all your great tutorials. This one is awesome. Since you said we could ask you questions, I know you're busy, but maybe you could help me and possibly others that follow me.

I'm trying to determine what size round core will fit my PK??? Any help would be appreciated.

I remembered a KnotHead thread with formulas.
http://www.khww.net/forum/viewthread.php?forum_id=16&thread_id=429

knotworkn wrote:
Quote:
The tightest packing and hence the smallest diameter will occur when the angle of the cordage at the bight pin location forms a 90 degree angle. Using this as the basis an assuming no riding up on top of any other strand/s and a cord diameter small with respect to the TH's inner diameter then, the equation I use is

Dia = [(0.45)*(dia)*(Passes)*(Bights)]

Where Dia = the inner diameter of the TH knot
dia = diameter of the cordage or width of the lace
Passes = number of passes made parallel to each cord
Bights = bights
0.45= squre root of 2 divided by Pi


Also in the eZine I found this:

Sidney Wood wrote:
Quote:
About Interweaves
In most cases the circumference or diameter of the knot is the critical factor and we have to adjust the parts to get the right number, for the interweave, as needed and accept the length that results. For normal type one and two pineapples you use the number of bights in the outer bight boundaries as the basis for diameter. The results of the calculations for interweaves will not come quite as close to a particular target value but they usually come close enough for government work.

Diameter = (.45 X string width) x bights.



So if I'm doing this right for the Type 3 - 4 pass (from the 7Lx6B Turk's Head):

.45 x 5/32" or .15625" (my cord size) x 4 (passes) x 6 (brights) = 1.6875". So I think I need about 1 5/8" or 1 3/4" core. Does this sound about right to you?

I do know I'd rather throw it away than try to loosen it up to put a different size core in it. I tried that with a PK before and got it to work but it was twice as hard as tying the PK to begin with. What a rat's nest that was! LOL

I started on a 2 1/2" mandrel (spray can) doing the 2nd and 3rd strings and then it started getting tight so I moved down to a 2" mandrel (another can) for the 4th string.

I just finished it tonight and I haven't even tightened it up yet, see the pic below on a 2" mandrel.



Also, I was wondering what sequence you tighten the strings up. Would you do the 2nd and/or 3rd ones first because they are in the middle?

Thanks again for all your fine work, Dan, and any help you could give to these questions!!!

Rick

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hello skyout...
....that is a nice looking knot!...as for a formula to figure out
what size ball or core to use??....i don't have a formula...for the
most part my method has always been to cut the cords extra
long on your first knot and keep a good (k)notebook and keep
good records!!....a lot of trial and error, but with good knot tyers
judgement you can usually come close the first time and get it
right the second time??!!....and you can also ask other knot tyers
what size balls/cords/cores they use...a nice complete set of
mandrels also helps!!...etc...

 

...the cord is 2mm Marlow and the wooden ball is 5/8", but
maybe a 3/4" wooden ball would work too???!....etc...

...when tensioning this knot i try to go from left-to-right...and
go slowly...i use the japanese marlinspike and the Osborne 477
fid to do the tensioning...tensioning is the most important part
of tyeing all knots so take your time....you might experiment
with the directions and find your own method??....this knot is
used a lot and folks make some beautiful projects with it!!..

Dan-Alaska


***************************************************
***************************************************

Thanks Dan. So if I get a bunch of different size mandrels and I get this PK to fit one of them, is that the correct size for a spherical core for the same knot? Say I put it on a 1 3/4" mandrel and it fits perfect when tightened; then will it fit correctly around a 1 3/4" round core?

**************************************************
**************************************************

hello skyout...
....it sort of works like that??...you want to tension the pineapple knot mostly while it is on the mandrel...then slip it on the ball...the mandrel should be approx. the same size as the ball??...(you'll know exactly what is what with the first one you make!)...and then finish tensioning it...but you still have to do some experimenting and get to know your cord and knot and ball sizes...and you will no doubt be making quite a few different projects...etc....you should be able to figure it out fairly easy and just keep good notes....

 
...the two large knots were made by Charles Allard - France

...the cord is 3mm poly from KJK Ropeworks...the wooden ball is 1 3/8" dia....(the cord i used for the instructions is 2mm poly from KJK)..

KJK Ropeworks

 http://pineapple.myfunforum.org/about20.html



...i use the japanese marlinspike to tension the knots...

Dan-Alaska


************************************************
************************************************
How Do All  Wink

Rick; I know of no formula that can match a core to any given knot made in whatever diameter of cord, I am not saying there is not one, but with so many variables, human ones included I can not see that a formula would work in every instance.

I use a different method which involves reversing what you are trying to do, why try to find a core to fit a particular knot? why not make the knot to fit the core you have or can get?

For instance, a Braider making a Bosal will make a foundation on the ends of the the formed bosal using other knots and the strands from the braided covering of the Bosal, then the Braider will make a Pineapple knot (Called a Heel Knot when used for this purpose, though in reality it is the whole that becomes the Heel Knot) The braider will keep on adding extra passes until the foundation is completely covered.

With experience and a good deal of cock-up's a knot tyer or braider will eventually have a knowledge of what knot in a given material will fit the foundation they have, so the experienced Braider will know what knot whith how many passes in whatever width of cord or lace they are using will fit a given foundation.

I notice from you pineapples that you double some passes, why not add an extra pass in another colour instead of doubling your original passes?

If your knot does not cover the foundation you want to use add another pass either the same size as the knot you started with or a smaller on nested inside the bight boundaries of the larger knots.

From the work you have done allready you should find it a snip to add another pass to a knot.

Don't let the knot detemine the core size, chose a core that is about the size you want your finished article to be and then make the knot to fit the core, Simple

I hope this helps a little.

Take care,
Barry Wink
_____________________________
Barry Brown.
Rope & Canvas Craftsman.
Practical Works of Art,
Inspired by Tradition.
http://myweb.tiscali.co.uk/ropeandcanvas

*************************************************
*************************************************

Thank both of you gentlemen. I don't guess there is any "quick" way to gain this knowledge except tie, tie and tie some more, so I'm off to tie. This really is a pleasant journey and I appreciate all the patience you've shown and the help you've provided.
Thanks again,
Rick

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PostPosted: Thu Sep 03, 2009 6:23 pm Reply with quote
Knotical
 
Joined: 03 Sep 2009
Posts: 12

Location: Chicagoland


Hi Barry,

I just posted a response on KHWW that this thread spun off from that may be more what you were looking for in a formula.

_________________
Regards,
JP (aka Knotical)
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PostPosted: Fri Sep 04, 2009 1:34 pm Reply with quote
Barry
 
Joined: 01 Dec 2008
Posts: 42

Location: England


Knotical wrote:
Hi Barry,

I just posted a response on KHWW that this thread spun off from that may be more what you were looking for in a formula.


How Do JP  Wink
Please forgive me for my ignorance; but I am not sure what you mean by the above  Confused
It was not me looking for a formula or asking the original qustion, I do not use or need them which is what I stated in the post above.
Sorry for not being on the same playing field if I have missed the point here Embarassed

Take care,
Barry  Wink

_________________
Barry Brown.
Rope & Canvas Craftsman,
and Net Maker.

Practical Works of Art,
Inspired by Tradition.

http://myweb.tiscali.co.uk/ropeandcanvas
http://ropeandcanvas.blogspot.com/
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PostPosted: Fri Sep 04, 2009 3:06 pm Reply with quote
Knotical
 
Joined: 03 Sep 2009
Posts: 12

Location: Chicagoland


Barry wrote:
Knotical wrote:
Hi Barry,

I just posted a response on KHWW that this thread spun off from that may be more what you were looking for in a formula.


How Do JP  Wink
Please forgive me for my ignorance; but I am not sure what you mean by the above  Confused
It was not me looking for a formula or asking the original qustion, I do not use or need them which is what I stated in the post above.
Sorry for not being on the same playing field if I have missed the point here Embarassed

Take care,
Barry  Wink


Hey, Barry,

What I was addressing were these comments of yours:
Barry wrote:
I know of no formula that can match a core to any given knot made in whatever diameter of cord, I am not saying there is not one, but with so many variables, human ones included I can not see that a formula would work in every instance.

I use a different method which involves reversing what you are trying to do, why try to find a core to fit a particular knot? why not make the knot to fit the core you have or can get?


To clarify, I didn't mean to imply that you were looking for a formula.  Rather, based on what I read, this was more of what you would want in a formula.  That is, if you used them.  Wink  Which, not surprisingly, is also what I want in a formula since I do use them.

I completely agree with you that there is probably no formula that can match a core to any given knot made in whatever diameter of cord.  However, this formula modification is more in line with your "different method" insofar as it matches the [Turks Head] knot to the core you already have and not the other way round.

And I agree with your next point too, "With experience and a good deal of cock-up's a knot tyer or braider will eventually have a knowledge of what knot in a given material will fit the foundation they have."  I've said a very similar thing about one of my other hobbies; Good woodworking comes from experience; Experience comes from bad woodworking.  When I make mistakes I learn.  But when I get it right I learn too.

The way I see it, a formula which helps a tyer (of any experience level) calculate how many bights or passes will be needed on a size particular core will save a lot of time and let the tyer produce more useful knots and fewer 'experience' opportunities.  It's just a tool, like a fid or mandrel, or, like the mother of all formulas - GridMaker.

If I gave offense or caused needless confusion, please forgive me.   Embarassed  I've been trying to limit myself to only needful confusion.  Laughing

_________________
Regards,
JP (aka Knotical)
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PostPosted: Fri Sep 04, 2009 3:45 pm Reply with quote
Barry
 
Joined: 01 Dec 2008
Posts: 42

Location: England


How Do JP  Wink

I see what you mean now, Sorry for not seeing what you were saying, the only confused one here was me and I was confusing myself:D

I will have a proper look at the topic this weekend, and reply on KHWW.

Take care,
Barry  Wink


_________________
Barry Brown.
Rope & Canvas Craftsman,
and Net Maker.

Practical Works of Art,
Inspired by Tradition.

http://myweb.tiscali.co.uk/ropeandcanvas
http://ropeandcanvas.blogspot.com/
View user's profile Send private message Visit poster's website
(transferred posts): formula
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