7.25" gauge track

[Ikcdab]

In addition to my 00 layout that you will have seen, I am embarking on a 7.25" gauge railway round the garden.
I have ordered some 21mm aluminium flat bottom rail.
I have successfully built turnouts in 00, so can i also make turnouts in 7.25 using scaled up methods?
I am thinking that rather than needle files on my 00, i can use my angle grinder to shape the 7.25 rail. Its 21mm aliuminuim so should be fairly soft to shape. I am also thinking to use jigs to help me get the 1:8 angles on the crossing vee rails.
I am hoping to be able to bend the wing rails by holding them in the workmate and using (careful) brute force. Then bolting it through the web with spacers to assemble the vee.
Point blade planing similar with the angle grinder, having marked the rail first.
Is this all possible? Any advice gratefully received.
I will also post this on rmweb and see any feedback.
Many thanks
Ian

 

[Bill Campbell]

Hi Ian

Although not 7.25" gauge you may find this topic on the Western Thunder Forum of interest:

https://www.westernthunder.co.uk/threads/breaking-ground-finescale-of-a-sort.9728/

Regards.

 

[Phil O]

Hi Ian,

Before bending Aluminium in anger, try a small test piece, Ally has a tendency to crack and break, due to work hardening. You may be OK with the radii required for turnout components.

The remedy is to rub the area to be bent with Cold Tar Soap and then gently warm the area until the soap goes black and then bend it.

 

[Justme Igor]

What Phil o said.
Aluminium will crack and break due to work hardening.
It will bend so far before it cracks.
Try to bend somewhere silent with a experimental piece.
Listen for the cracking.
Now you have set the max curve.
Take 50% of this to keep your loco's save.

Heating first with a blow torch it is a tricky one, personal i would not even try this.
The eutectic state is pretty short, there will be no collaring before this.
When decolouration happens, you are to late.
Aluminium melts at even at 640C!(Blend depending) eutectic state is around 580C, a blow torch can quickly become 1800C(type depending).

If i may suggest: "welding" pieces together for your frog wing and safety rail.

Last but not least:
Dont grind aluminium with a "normal" steel/iron/inox blade, yes you are correct a alu blade.
Grinding alu can heat up alu very quickly, "choking" your blade.
Even on a ?sanding beld/beld sander? it can be that hot that pieces will melt into your sanding paper.
Thus also weaking your alu.

When you decide to go for welding keep below 500C

To work with aluminium i use 40grid and 60 grid belds on a low speed on my machine.
Even a fine wood working file will do a good trick.
Most wood working cutting tools will do a fine job.
A table saw with fine teeth is a must have.(HPL blade)

I am very afraid(almost certain) that while bending your wing rail it will buckle up at the inside and rupture on the outside.
Making a cut at the outside and a v cut in the inside ...can...should counter this.
Again with heating, i have second thoughts about this, it is to massive.

Welding is done preferably electric or with a simple inox gas welder, tig was it i believe.(could be mig)
Point blades i would use a router with a fair hardend wood bit or special alu bit.

Alu is a fine material, it likes to be cut.(like hard lead or soft copper)
For upscaling i think it can be down.
Why not downscaling from real?

I hope my guessing/rambling is getting you some closer to what you want.

My two cents, best Igor.

 

[Justme Igor]

It seems to me that they use for their wing rail a casted section.
Also some sort of hard plastic could be used (pvc hpl) for there "frogs".
I could cast a frog for you.
I need time and good drawings.
You must do the sanding!
I am almost certain they use azobe wood (maybe oak?)and stainless/inox steel for there throw bar.

https://maxitrak.com/trackaccess-item/point-kits-ready-to-lay
Look closer at their pictures to get yourself a idea or two.

 

[James Walters]

I've built a couple of 5" gauge turnouts using 16mm aluminium rail, and an observation is that it can wear surprisingly quickly at the common crossing (more so in 7 1/4" gauge), where substituting with steel could be advantageous. There's quite a bit of mass in a 7 1/4" train loaded with passengers. From memory my turnouts were about 12' radius and frankly 'narrow gauge' in appearance and construction. I used PNP plastic chairs to hold the rail, and screwed the splice joint on the common crossing into tapped holes in the point rail. I had no problems with them despite their crudity.
I 'planed' my switches by cutting them on the bandsaw and finishing with a flap disc in the grinder. Grinding aluminium is not fun, and milling takes ages.
The rail foot on 21mm rail is quite wide which makes bending tricky but not difficult, although it tends to twist. I notched mine inside and outside the bend and tig welded the joints up after bending.

My opinion is that building a turnout in a model engineering gauge is simpler than in a model railway gauge as the tolerances tend to be quite generous, and no-one pays any attention to the PW until it needs repair.

It would be nice if suitable bullhead rail was available - but I don't think it is currently.

I'm building a 7 1/4" bagnall, and I will need to consider track for that myself at some point. I was going to use 10x25mm steel bar stock for my turnouts for simplicity and strength.
It wouldn't be difficult to adapt the Plug Track principles to create realistic baseplates for flat bottom rail which could press into sockets jig-drilled into the sleepers with a forstner bit. Hmmm, that's got me thinking.

Good luck with your project, I'd be very interested to see your progress posted on here.

James

 

[Steve_Cornford]

Last week I was treated to ride on the 7¼" gauge Beer Heights Light Railway by two of my grandchildren
Two locos in steam. A good time was had by all!
Steve

 

[Ikcdab]

What Phil o said.
Aluminium will crack and break due to work hardening.
It will bend so far before it cracks.
Try to bend somewhere silent with a experimental piece.
Listen for the cracking.
Now you have set the max curve.
Take 50% of this to keep your loco's save.

Heating first with a blow torch it is a tricky one, personal i would not even try this.
The eutectic state is pretty short, there will be no collaring before this.
When decolouration happens, you are to late.
Aluminium melts at even at 640C!(Blend depending) eutectic state is around 580C, a blow torch can quickly become 1800C(type depending).

If i may suggest: "welding" pieces together for your frog wing and safety rail.

Last but not least:
Dont grind aluminium with a "normal" steel/iron/inox blade, yes you are correct a alu blade.
Grinding alu can heat up alu very quickly, "choking" your blade.
Even on a ?sanding beld/beld sander? it can be that hot that pieces will melt into your sanding paper.
Thus also weaking your alu.

When you decide to go for welding keep below 500C

To work with aluminium i use 40grid and 60 grid belds on a low speed on my machine.
Even a fine wood working file will do a good trick.
Most wood working cutting tools will do a fine job.
A table saw with fine teeth is a must have.(HPL blade)

I am very afraid(almost certain) that while bending your wing rail it will buckle up at the inside and rupture on the outside.
Making a cut at the outside and a v cut in the inside ...can...should counter this.
Again with heating, i have second thoughts about this, it is to massive.

Welding is done preferably electric or with a simple inox gas welder, tig was it i believe.(could be mig)
Point blades i would use a router with a fair hardend wood bit or special alu bit.

Alu is a fine material, it likes to be cut.(like hard lead or soft copper)
For upscaling i think it can be down.
Why not downscaling from real?

I hope my guessing/rambling is getting you some closer to what you want.

My two cents, best Igor.

Hi Igor, thanks, thats really helpful, thanks.

 

[Ikcdab]

View attachment 9729

It seems to me that they use for their wing rail a casted section.
Also some sort of hard plastic could be used (pvc hpl) for there "frogs".
I could cast a frog for you.
I need time and good drawings.
You must do the sanding!
I am almost certain they use azobe wood (maybe oak?)and stainless/inox steel for there throw bar.

https://maxitrak.com/trackaccess-item/point-kits-ready-to-lay
Look closer at their pictures to get yourself a idea or two.

Hi Igor, intersting picture, but i want something that looks more prototypical. Ie with proper crossings. I am going to use 3 x 2 for the sleepers as I am after a narrow gauge look.

 

[Ikcdab]

I've built a couple of 5" gauge turnouts using 16mm aluminium rail, and an observation is that it can wear surprisingly quickly at the common crossing (more so in 7 1/4" gauge), where substituting with steel could be advantageous. There's quite a bit of mass in a 7 1/4" train loaded with passengers. From memory my turnouts were about 12' radius and frankly 'narrow gauge' in appearance and construction. I used PNP plastic chairs to hold the rail, and screwed the splice joint on the common crossing into tapped holes in the point rail. I had no problems with them despite their crudity.
I 'planed' my switches by cutting them on the bandsaw and finishing with a flap disc in the grinder. Grinding aluminium is not fun, and milling takes ages.
The rail foot on 21mm rail is quite wide which makes bending tricky but not difficult, although it tends to twist. I notched mine inside and outside the bend and tig welded the joints up after bending.

View attachment 9728

My opinion is that building a turnout in a model engineering gauge is simpler than in a model railway gauge as the tolerances tend to be quite generous, and no-one pays any attention to the PW until it needs repair.

It would be nice if suitable bullhead rail was available - but I don't think it is currently.

I'm building a 7 1/4" bagnall, and I will need to consider track for that myself at some point. I was going to use 10x25mm steel bar stock for my turnouts for simplicity and strength.
It wouldn't be difficult to adapt the Plug Track principles to create realistic baseplates for flat bottom rail which could press into sockets jig-drilled into the sleepers with a forstner bit. Hmmm, that's got me thinking.

Good luck with your project, I'd be very interested to see your progress posted on here.

James

Hi James, thanks thatys really helpful. I have table saw and bandsaw and have come to the same conclusion as you. that it is doable. Bending will be the issue, i have printed off a 7.25" templat from templot, so I am ready to go.
I thought i would make a template out of MDF as a guide for bending wing and check rails. Might make those tomorrow.
Ian