Drawing anomalies

[learner johnParticipant @learnerjohn78074]

Hi! Iv'e started work on a "Vulcan" beam engine using the original bound volumes dated '54 and '55. I also purchased working drawing . As I have found a difference in some measurements between the volumes and the drawing,would I be correct if I adhered to the working drawings only?

[learner johnParticipant @learnerjohn78074]

[JasonBModerator @jasonb]

Hard to say as I've not done the Vulcan, a lot will depend on if the working drawings have been revised which is not always the case.

There is one error listed here

Think I have the drawings somewhere if you say what the errors are you have found I'll see what mine say

J

[learner johnParticipant @learnerjohn78074]

Hi! The error referred to concerns the connecting rod. The distance between the top and bottom hole is given as 61/2 inches and the bottom hole diameter as 1/4 inches whilst on the working drawing its given as 6 9/16 inches and the bottom hole as 5/16 inches.

[old AlParticipant @oldal]

Not done a Vulcan either, but the dimensions indicated can be worked out with a bit of cross reference with other bits.

Model engineering drawings can be a minefield of errors, so just double check before you cut.

I would never use magazine articles as a dimension reference, use the proper drawings, but take care.

[Gary WoodingParticipant @garywooding25363]

My late mentor advocated redrawing everything in CAD before cutting metal. I heed his advice; its amazing how many errors are revealed.

Gary

[nigel jones 5Participant @nigeljones5]

If it looks right it probably wont be, if it doesnt look right it definately wont be and if it looks totally wrong then it probably never ran in the first place! Welcome to the world of expensive badly drawn plans!

[roy entwistleParticipant @royentwistle24699]

I built the Vulcan years ago and used the drawings supplied with the castings I don't remember any problems but I tend to make one part fit its mate anyway ie I would make cylinder end covers fit the cylinder

Best of luck Roy

[stan pearson 1Participant @stanpearson1]

Hi John

I agree with Roy you should try building Les Warnett`s 9F i use the drawings as a guide only and make the parts fit as i go along, its almost like building a free lance.

Regards

Stan

[LambtonParticipant @lambton]

Learner John,

I am building a Vulcan and have found the same anomaly between the ME articles and the drawing supplied with the castings. I suggest it is best to work to one or the other and carefully check each drawn detailed part.

Eric

[Gordon WParticipant @gordonw]

Easiest and best way to check detail drawings is to draw an assembly from the details, either CAD or on a board. This is how I did it when earning money. CAD will show up straight away, hand drawing will have to note things like hole dias.

[JasonBModerator @jasonb]

I would say the working drawings are correct.

If you add the height of the A frame and trunion bearing ctr height that gives 7". Subtract from that the main bearing ctr height of 7/16 and that gives a ctr to ctr distance of 6 9/16 so a conrod of this length would give equal movement of the beam from the horizontal.

The crank pin is 5/16 so probably also best to make the bearing this size rather than the 1/4" given in the article, you can keep the bearing OD as 3/8"

J

[learner johnParticipant @learnerjohn78074]

Many thanks for your interesting replies

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