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Frames for the 2-8-2 cut


RedgateModels

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Finally, I have some real frames. First I cut two pieces of copperclad pcb material to size then spray glued a copy of the frame "comic" to the top piece. These were then clamped to some 12mm mdf. Holes were bench drilled to take some 4ba screws right through the sandwich to secure everything once the clamp was removed.

 

1.6mm pilot holes were drilled through at the axle locations. I've done this so that I can use crankpins fitted in the mdf as a jig for setting up the coupling rods. As the frames and jig were all drilled at the same time, the theory is that the rods should fit!

 

The frame material was removed from the mdf and clamped back together with the original screws and the bearing holes opened out to 3.5mm. These two halves could then be clamped together with 6ba screws for shaping.

 

Here's a photo of the "jig" and the two frames bolted together after intial rough shaping.

 

blogentry-6717-127382669378_thumb.jpg

 

Note arrow showing which way is "front"

 

Here's a photo of the frames held up against the body

 

blogentry-6717-127382695528_thumb.jpg

 

And here's a frame against the original drawing, with one of the Kemilway 8F hornblock/spring etches that will be soldered to the frames. Note I've used the hole in the etch to scribe a circular gap in the copper to isolate the bearing from the rest of the frame. I will have to do similar around the cylinder strecher and motion support bracket to prevent shorts.

 

blogentry-6717-12738269943_thumb.jpg

 

smile.gif

 

Next step is to machine up some 8.5mm spacers for a set of Comet frame jigs. As I'm using quite thick double sided PCB material the spacers are correspondingly thin. The figure of 8.5mm was derived from a formula in Iain Rice's book on chassis construction.

 

The "EM" spacers from the tender chassis will be pressed into service for the loco as soon as I've cut them down to 8.5mm too. Now, where did I put that lathe .......

 

EDIT:

 

Thanks to micknich2003 for agreeing to machine up the 8.5mm frame jig spacers, saves me digging the lathe out of the garage biggrin.gif

 

 

 

 

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I'm looking forward to this one immensely - nice to some progress at last :lol: And that the Brit body is being used! B)

 

Looking smashing chap, good luck and it already has that air of success about it. :)

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  • RMweb Gold

Cheers mate, body will be attacked sometime as a Comet detailing kit is going on and de Selby of this parish has kindly offered to do some flush fitting footplate sides for me similar to the ones he did for his "Clan Challenge" biggrin.gif

 

Lets get the chassis sorted first though. The valve gear should be "interesting"

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  • RMweb Gold

The valve gear and coupling rods will be "derived" from Comet 9F bits. The coupling rods all have to be reduced in length, OK that's not so bad as they are laminated up. The con-rod and at least the accentric link have to be lengthened so I'm going to have to find some filler material from somewhere - hopefully bits of left over coupling rod etch blink.gif

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looking good again redgate! got Hornby mag today and have seen summit in so will havea read on saturday!

:)

cheers ian.

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