Drawing problem

[deeferdog]

Hi to all. Once again I have struck a problem interpreting these drawings for the Bolton 12 Beam engine. I cannot work out the overall length of the crank nor the thickness of the crank at the crank pin end. I feel really stupid at having to ask this but I'm stumped. There is no scale on the drawings and the only way that I can see to do is to draw it as accurately as I can in CAD and use the measuring tool. What am I missing here?
Regards, Peter

 

[Cogsy]

Only a guess but I'd say this piece was a casting and the dimensions you are missing are non-critical. So I'd make my best estimate, basically so it 'looks right' as per the drawing. Of course if there are other pieces in close proximity that need clearance you'll have to adjust as necessary. Sorry I couldn't be more helpful.

 

[Jasonb]

As Cogsy says looks like it was cast and only the critical dims are given.

I would say pin end is 1" dia and crank end 1 1/4" dia

Thickness is 21/32" + 1/16" at the crank end

Pin end say 3/8" + 1/16"

 

[Chiptosser]

If you use grafting paper, lay out the dimensions that you have.

Then you can draw on the paper to size or larger and figure out the dimensions.

You may want to make some changes to, how the part looks, this will help you figure the dimensions.

I am going to say that your rough saw dimensions are: .750 x 1.25 x 2.750

 

[bazmak]

I have worked in the DO all my life and all drgs said DO NOT SCALE
However there are exceptions and this is one case.I have made 2 steam locos
using old drawings and mostly non critical dims are missing.Do as everyone has said with the alternate option of scaling.Measure the missing dim and find
a similar marked dim and scale,adjust etc to suit what you think is right,looks good and fits(clears ) etc Usually when casting are supplied most non machined sizes are not specified.If you are making from scratch you have
to supply the missing dims yourself. Regards Barry

 

[deeferdog]

Thanks for all the help. Regards, Peter