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Offline aclassifier  
#1 Posted : 23 August 2020 18:39:28(UTC)
aclassifier

Norway   
Joined: 18/03/2012(UTC)
Posts: 114
Location: Trondheim
I have discovered (correct or not) that if I..

..connect two straight track to an open S made by two curved track (59076) back-to-back, then in theory I think I should have found that the straight track were offset by 23.6 cm - but in practice, on the floor I measure 22.0 cm.

If I do the same for my shelf's track (picture), where I have cut a 59076 in two, the discrepancy is about 60 mm on paper but 41 mm measured.

I have written about this in detail at [1]. But the basic summary is given above. What did I get wrong?

Øyvind
PS. I will link up this thread in my blog.

[1] My Marklin (Hübner) track (disclaimer: no money, gifts etc. on any of my blog notes)

[2] UserPostedImage
Offline phils2um  
#2 Posted : 24 August 2020 08:00:30(UTC)
phils2um

United States   
Joined: 12/01/2016(UTC)
Posts: 122
Location: Michigan, Ann Arbor
Your calculations are correct. X=R(1-cosø) where X = the offset, R = the radius of the circle, and ø = portion of the circle the section the track represents. Plug in 22.5º and 1550mm and you get 118mm. With back to back identical curved sections the total offset is 2X or 236mm. I suspect the radius is actually "relaxing" when you set this up with real track.
Phil S.
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Offline Purellum  
#3 Posted : 24 August 2020 08:58:45(UTC)
Purellum

Denmark   
Joined: 08/11/2005(UTC)
Posts: 3,366
Location: Mullerup, 4200 Slagelse
Cool

Originally Posted by: phils2um Go to Quoted Post
Your calculations are correct.


I agree, and I spend some time yesterday trying to figure out what went wrong.

If I make 1/4 circle, using 59076s, to be sure they end up making a 90º turn,
and I then measure the offset at 11,25º, then I measure 30mm - which is as the calculations.

If the cut you made in the 59076 is not 100% radial to the curve, this can be the reason for your problems,
or just the tracks not sitting perfect in the sleepers.

Per.

Cool

If you can dream it, you can do it!

I, the copyright holder of this work, hereby release it into the public domain. This applies worldwide.

In case this is not legally possible:
I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law.

UserPostedImage
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Offline aclassifier  
#4 Posted : 25 August 2020 10:51:30(UTC)
aclassifier

Norway   
Joined: 18/03/2012(UTC)
Posts: 114
Location: Trondheim
Thank you, Phils2um and Purellum!

I too, thought that it might have been my cutting. That's why I also tested the not-cut 59076 and made sure that they really clicked well into position. I cannot put a paper in the joints. And I measured along the planks in the wooden floor.

I like the hypothesis of a "relaxing" track. I will see when I get enough of them to make a circle, how the ends meet. I assume the circle would be open and that I would have to push them together. That the radius is a little more than 1.55, kind of. Stay tuned. I will update here.

Still I am rather confused about why this is so.

Also, strange that the picture of the 59076 is different from what was in the box.

Øyvind
Offline hxmiesa  
#5 Posted : 25 August 2020 14:01:31(UTC)
hxmiesa

Spain   
Joined: 15/12/2005(UTC)
Posts: 3,296
Location: Spain
How wide is your cutting disc?
I mean, if you ground off a lot, and then file/round it off to get rid of the burrs, would that not account for SOME of the discrepancy?
Best regards
Henrik Hoexbroe ("The Dane In Spain")
http://hoexbroe.tripod.com
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Offline aclassifier  
#6 Posted : 25 August 2020 14:46:46(UTC)
aclassifier

Norway   
Joined: 18/03/2012(UTC)
Posts: 114
Location: Trondheim
Originally Posted by: hxmiesa Go to Quoted Post
How wide is your cutting disc?
I mean, if you ground off a lot, and then file/round it off to get rid of the burrs, would that not account for SOME of the discrepancy?

Ok, there's something called a cutting disc? Please explain.

I cut mine like I wrote in the blog note:
Quote:
Cutting a curved track is a little tricky. I cut and glued a thin paper strip and positioned it on the track, then folded the paper over at the middle and marked, first the one track, then with another paper strip on the other – and cut one and one. That’s because the outer rail is longer than the inner, and both need to be cut exactly at the middle.

If I after the cutting place one on top of the other they are as equal as I am able to observe. But since I too was suspiscious about that, that's when I checked a non-cut 59076 and found a large discrepancy there, too.

For my half 59076 then 41 mm instead of the 60 mm theoretical is quite ok on my shelf. But if I really wanted 60 mm, I could, as you say, file it. But that would have looked strange, because now the edges are nice and smooth.



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