engine throw

[brickyParticipant @bricky]

In a construction article of the engine I am trying to make sebse of before I start building,has a throw of 20mm yet in an image of a jig for offsetting the crank pin it has 1800.I assume that the point has been missed and should resd 18mm.The bore is 18mm and I have read somewhere that the throw and the bore should be the same,if not so i have to decide which measurement is correct.I would appresiate some advice on this as I am trying to make a drawing before I start.

[JasonBModerator @jasonb]

Throw or more usually twice the throw which is the stroke and the bore do not have to be the same, higher reving engines may have a stroke shorter than the bore where as something slow like a hit and miss engine tends to have the stroke quite a bit more than the bore.

Same for steam, a high speed marine engine will have a shorter stroke than a slow mill engine if both have the same bore.

[bernard towersParticipant @bernardtowers37738]

What engine, perhaps someone has a different article.

[JasonBModerator @jasonb]

Bricky, I just looked at the article, I think the jig should say 180deg rather than a measurement.

It’s the 2 piston / 3 conrod engine from 2018

[brickyParticipant @bricky]

Thanks Jason that helps a lot.

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