Garden Railway Forum

Hello,

I found this post about this nice loco, and I would like to make it.

Just a quick question : Is it 32 or 45mm in your modified design Philipy

Hi Sam,
My version is 32mm.

Oki,

As I like your improvment, I will have to do some engineering to convert this to 45mm.

Sam95 wrote: ↑Mon Jun 23, 2025 9:40 pm Oki,

As I like your improvment, I will have to do some engineering to convert this to 45mm.

I have an incomplete prototype that widened the space between the frames to make it capable of adjusting the gauge up to 45mm, though if you don't intend it to ever go on 32mm track it might make more sense to narrow the frame spacing and switch to an inside frame setup. I'll see if I can dig up any of my extra files from playing around with that.

Please note that I was (and still am) an inexperienced designer and as others have pointed out, the cab is quite small for the average 16mm figure. I tend to have my shorter-than-average driver and fireman ride on the cab steps and lean out if they don't fit comfortably, but if I were building again from scratch I would definitely raise the cab roof by several mm.

drewzero1 wrote: ↑Tue Jun 24, 2025 5:21 am

Sam95 wrote: ↑Mon Jun 23, 2025 9:40 pm Oki,

As I like your improvment, I will have to do some engineering to convert this to 45mm.

I have an incomplete prototype that widened the space between the frames to make it capable of adjusting the gauge up to 45mm, though if you don't intend it to ever go on 32mm track it might make more sense to narrow the frame spacing and switch to an inside frame setup. I'll see if I can dig up any of my extra files from playing around with that.

I am not sure to understand well : you mean to put the wheels outside the frame instead of inside ?

drewzero1 wrote: ↑Tue Jun 24, 2025 5:21 am

Sam95 wrote: ↑Mon Jun 23, 2025 9:40 pm Oki,

As I like your improvment, I will have to do some engineering to convert this to 45mm.

Please note that I was (and still am) an inexperienced designer and as others have pointed out, the cab is quite small for the average 16mm figure. I tend to have my shorter-than-average driver and fireman ride on the cab steps and lean out if they don't fit comfortably, but if I were building again from scratch I would definitely raise the cab roof by several mm.

I compared your measurement with my LGB loco, and it seems that if I scale up your parts from 112% in cura the total side will be more accurate with my existing locos. With this scale up the cabine will be 10cms height.

Sam95 wrote: ↑Thu Jun 26, 2025 8:37 am I am not sure to understand well : you mean to put the wheels outside the frame instead of inside ?

Yes, but the width between the side frames will need to be narrowed slightly to make it work out right with the track gauge. I believe that's how the Quarry Hunslets could be built for three foot gauge instead of the usual two foot, see Steve's model here for visual reference: https://www.thingiverse.com/thing:6645291

(Thornas was originally meant to be a Quarry Hunslet, but soon turned into more of a Bagnall or Kerr Stuart Skylark.)

Steve did use parts from the PDF Models kit including the bits where the cylinders attach, this is then attached onto the actual frames giving the straight sided or D-shape smokebox. Real quarry Hunslets built for gauges of around 2ft 6" and upwards had inside frames and a curved smokebox, this meant the majority of the same parts could be used

tommygander1941 wrote: ↑Fri Jun 27, 2025 1:36 am Steve did use parts from the PDF Models kit including the bits where the cylinders attach, this is then attached onto the actual frames giving the straight sided or D-shape smokebox.

I'm not sure that is correct Tommy? I used Steve's stl's for my Quarry Hunslet and although I redrew some and played around with various details, the basic model worked fine and was complete, not needing to buy anything in from PDF.
viewtopic.php?t=14820&hilit=quarry+hunslet.

However, coming back to Thornas, it should be fairly simple to modify the chassis/frames to produce either inside or outside frames for either 32 or 45mm gauge wheels, depending on builders preference! Bare in mind that Thornas is not a prototypical loco but is a sort of hybrid of a Q.Hunslet and KS Firefly plus some imagination!

Ah yes, well the 32mm one is good. It's more the 45mm one, the cylinders are spaced further out from the frames but include the top bit of the frames which go against the smokebox, on the real loco they should be part of the main frames yet on this 3D model they are further apart from the actual frames which gives the D shape smokebox, when it should be curved