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Ransomes and Rapier 70ft Turntable


T30RRA
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My first hour saw the first two boards screwed together and the well inserts dry fitted, a light sand to the edges is required before taping and gluing into place. 

20210606_233203.jpg

20210607_001347.jpg

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  • 1 month later...

kind of answered my own question. 70ft real dia. divided by 43.5, gives 490.423 once converted to mm, divided by 360 degrees is 1.3622mm per degree so 4 degrees is 5.449 or 5.45mm spacings nearest damn it.

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You might want to revisit your flawed mathematics! The scale of the error in your calculation has been calculated to over 50 trillion places of decimals!

Dave

 

Edited by daifly
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50 minutes ago, daifly said:

You might want to revisit your flawed mathematics! The scale of the error in your calculation has been calculated to over 50 trillion places of decimals!

Dave

 

 

So what should the spacings be? I could very easily be wrong, trying to work out a formula that I don't normally use late at night is not a great idea.

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The approximate length of the race rail is pi*d. So, for a 70" diameter turntable, (the race rail is not quite at the extremity so the diameter of the race rail will be slightly less) the circumference is pi*70' on the prototype. For a 7mm scale model, this becomes pi*70*12(inches)*25.4(inches to mm)/43.5(scaled). That's 1540mm. With a chair every 4deg as you propose, that's 17.11mm chair centres not 5.45mm!

Dave

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2 hours ago, daifly said:

The approximate length of the race rail is pi*d. So, for a 70" diameter turntable, (the race rail is not quite at the extremity so the diameter of the race rail will be slightly less) the circumference is pi*70' on the prototype. For a 7mm scale model, this becomes pi*70*12(inches)*25.4(inches to mm)/43.5(scaled). That's 1540mm. With a chair every 4deg as you propose, that's 17.11mm chair centres not 5.45mm!

Dave

 

Thanks. The 4 degrees came from someone else on here who was building one. I appreciate the help. 

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Pretty good effort tonight. The other half then I need to do the bridge as the upper board needs checking against the bridge prior to fixing in place. 

20210720_233409.jpg

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  • 1 month later...
1 hour ago, gismorail said:

Coming on nicely I have to admire your patience not an easy thing to build :clapping:

The instructions take a bit of reading, that's for sure and the M2 nuts are often awkward to tighten up.

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