LGB point frogs

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Nigel B
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LGB point frogs

Post by Nigel B » Sun May 14, 2023 9:09 pm

Evening all
The FeckHallBahn started as sn LGB Stainz starter set and has evolved in many ways. One of these is that the 16mm world seduced me. Which leads me to the point (sorry). All my points are LGB R1 and that can’t be changed. Is there any way I can modify the frogs so that my fine scale stock doesn’t lurch in the gap that will allow my G scale stuff to continue? I run dead rail so no insulation issues. It would have to be something that I could do in-situ, lifting the points would be too destructive.
NB - I have very little engineering talent or skills!! And no machine tools.
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ge_rik
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Re: LGB point frogs

Post by ge_rik » Mon May 15, 2023 7:22 am

Many years ago, I modified finer profile wheels to run through LGB point frogs. I was focusing more on back to back issues, but you could use the same method to increase flange depth. As you can see my workshop facilities and construction techniques are dead basic.

https://riksrailway.blogspot.com/2012/0 ... heels.html

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Lonsdaler
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Re: LGB point frogs

Post by Lonsdaler » Wed May 17, 2023 10:15 pm

Rik's solution is ingenious, but I wonder if the same result could be achieved now via 3D printing? It would save a lot of fiddly labour. Various outlets will 3D print, and I'm sure one of the talented 3Ders in this forum could knock up the required .stl file for you? Just a thought.
Phil

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drewzero1
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Re: LGB point frogs

Post by drewzero1 » Fri May 19, 2023 5:16 am

Ooh, is that what's going on with your Dougal? I'd be happy to try my hand at some STLs for 3d printing, it seems like a simple enough thing to model. I should just need the diameter(s) of the wheels and the diameter of the axle. I would do it as a parametric model so different wheel and axle sizes could be created from the same model.

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Re: LGB point frogs

Post by drewzero1 » Fri May 19, 2023 5:52 am

I've sniped myself already. Here's an OpenSCAD script for a 3d model possibly approximating Rik's fix. I've used generic measurements from my own stock, but if you measure yours I can easily create some STLs and put them up somewhere.

Code: Select all

//Wheel insert for better running through LGB points
// Drewzero1 - May '23
$fn=200;
thickness = 1.5;
wheel_diameter = 23; // set your wheel diameter here (in mm)
axle_diameter = 3.175; // set your axle diameter here (in mm)
slot_width = 0.3; // slot for fitting over axle

difference(){
  union(){
    // main core - in two parts to provide chamfer
    cylinder(h=thickness/3, r=wheel_diameter/2-0.1);
    translate([0,0,thickness/3-0.01]){ cylinder(h=2*thickness/3, r1=wheel_diameter/2-0.1, r2=wheel_diameter/2.3); }
  }
  // axle hole
  translate([0,0,-0.01]){ cylinder(h=thickness+0.02, r=axle_diameter/2+0.1); }
  // slot to allow fitting over axle if wheels are installed
  translate([-slot_width/2,0,-0.01]){ cube([slot_width, wheel_diameter/1.9, thickness+0.02]); }
}
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ge_rik
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Re: LGB point frogs

Post by ge_rik » Fri May 19, 2023 8:18 am

Now that looks like a really neat solution. Full marks!
I must get the hang of OpenScad. It's perfect for this sort of thing.

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Re: LGB point frogs

Post by ge_rik » Fri May 19, 2023 9:07 am

This has reminded me that Simon has written the OpenScad code for producing a parametric flared steam dome.
https://gardenrails.org/forum/viewtopic ... me#p166669

I'm wondering whether it might be useful to gather these OpenScad links together in a new sticky thread.

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drewzero1
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Re: LGB point frogs

Post by drewzero1 » Fri May 19, 2023 10:31 am

I remember reading that one. Very impressive! :salute: When I made the dome for Thornas I just stacked three-four 'cylinders' with different end radii and counted on small size and low resolution to hide the kludge. The four or so OpenSCAD commands I know are all hammers, and from here, everything kind of looks like a nail.

Nigel B
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Re: LGB point frogs

Post by Nigel B » Fri May 19, 2023 12:36 pm

Thanks all
These replies didn’t appear in my email for some reason (it might have been because I was banging my head on the keyboard during 2 days of Musicians’ Union meetings).
I don’t have 3D printing facilities but that solution looks fabulous.
I’ve actually sorted it out now.
1) Build up of gunk on the wheel treads ‘machined’ off with a tiny flat head screwdriver. Looks like I’ve stumbled, sort of, on Rik’s solution
2) Back to back on the leading wheelset was 1mm too big. Corrected and fresh Loctite applied
3) The point blade tip was dropping below the LH running rail causing things to rock off (but at the other end). Shimmed that with some 0.0016 brass strip. Dead rail so no shorting worries.
4) Made the frogs longer with Jenolite steel epoxy putty. PSA - it goes off in <10 minutes when it’s 16°C…

Point Fettling (inc blooper reels!)
https://youtu.be/FHQ031UjsdQ
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Lonsdaler
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Re: LGB point frogs

Post by Lonsdaler » Wed May 24, 2023 8:36 pm

Difficult to see the change you've made to the frogs on the video, but it's obviously helped. Well done.
Phil

Sporadic Garden Railer who's inconsistencies know no bounds

My Line - https://gardenrails.org/forum/viewtopic ... 41&t=11077

Nigel B
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Re: LGB point frogs

Post by Nigel B » Wed May 24, 2023 10:23 pm

I didn’t think to do a before and after!! Next time, if there is one…
FeckHallBahn

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