# Help understand plan section



## Jack3M (Feb 12, 2019)

The photo shows a section of a shaft in plans for a steam donkey.  This shaft is called a drum shaft.  Regardless, the plan is confusing the heck out of me.  This is .5" shaft, drill rod. 

It appears to me that the #19 drill is to a depth of 7/8.  ?????
Then, the slot, it wider and deeper than the shaft if you go that route, but only 5/8 wide thru the shaft completely if you go by the drawing. 

So, the drawing is contradicting itself to me.  Now I am no machinist, but heck I am not sure.





I have looked further thru the plans and unable to find reasons for either the #19 hole or the slot.....yet.  Minimal drawings and pictures to go from on this....  It looks like something would lock into a slot or use that as some sort of engagement feature. 

Help!  LOL


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## Brian Rupnow (Feb 12, 2019)

The drawing is wrong. It contradicts itself. Possibly means a 1/16" wide slot completely through the 1/2" shaft.---A #19 drill is 0.166" diameter and the view where the slot is called out shows the slot being the same width as the drill.---Wait until you make some of the other parts and it may become clearer to you.---Brian


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## Jack3M (Feb 13, 2019)

Brian, as of now, that is where things will have to stand.  The author of the book and plans has expired, so..........  He explains things in a way I find difficult to understand, approaches things in a difficult manner when easier options are avail, so...........  Even been modifying materials to make things more financially feasible.


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## Dalee (Mar 1, 2019)

Hi,

Since you can't consult the author of the plans, you will need to determine just what is supposed to go into that slot and how it's supposed to fit first. But going by the print you show, I would ignore the the callout note and go by what was actually drawn and dimensioned.

So we can determine from the part drawing that the slot is the same width as the drilled hole and the hole intersects the slot. And the slot is cut through the 1/2" shaft on center.

Not to criticize non-professional engineers, because the "pros" are just as often guilty, this is a common error. Where callouts have nothing to do with what is actually drawn. And honestly, everyone who creates prints regularly has a "signature" in the way they dimension. And it can take some practice to learn to read someones prints.


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## Jack3M (Mar 1, 2019)

Interestingly, the drawing itself is correct.  That thing at the top is wrong.  That is not the only mistake in the plans.  Someone got 6 and 7 inch lengths wrong to get a 6" spread across the center also.  Had to remake that part and had to go buy stock for it.  Grr. 

The slot allows a piece that pushes a part to engage a clutch, which is spring returned.  Pretty cool, not one photo, not even mention in the write up.  LOL.  This has been an interesting project so far.  Yesterday got the first section of work completed.  Still need to make the brake parts, the engine parts, and the boiler.  (Steam Donkey)


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