Help reading print please

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LouStule
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Help reading print please

Post by LouStule »

This is a shaft for the Stuart Turner Oil Field Pump that I am building. I can't figure out why the print shows hatching on a section of one end of the part (#11). I'm not sure what they are trying to convey. Nothing else on the prints indicates what that hatching denotes. Anyone have any ideas on what the print is trying to "say"? Thanks.
print pic.jpg
John Hasler
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Re: Help reading print please

Post by John Hasler »

They are telling you that the hatched area shows a cross-section.
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rmac
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Re: Help reading print please

Post by rmac »

Hatching like that usually indicates what everyone calls a "sectional view". The idea is to show how the part would look if a portion of it was cut away. In this case, you're supposed to assume that the imaginary cut is slicing the part in half lengthwise.

They've done this here to avoid referencing the 3/16" dimension for the depth of the tapped hole to dashed (hidden) lines. In general, it's bad practice to dimension to hidden lines.

-- Russell Mac
LouStule
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Re: Help reading print please

Post by LouStule »

rmac wrote: Tue Aug 31, 2021 6:08 pm Hatching like that usually indicates what everyone calls a "sectional view". The idea is to show how the part would look if a portion of it was cut away. In this case, you're supposed to assume that the imaginary cut is slicing the part in half lengthwise.

They've done this here to avoid referencing the 3/16" dimension for the depth of the tapped hole to dashed (hidden) lines. In general, it's bad practice to dimension to hidden lines.

-- Russell Mac
Thanks. It's just that I've had many prints from Stuart and this is the first time I can recall them ever doing this. Much appreciated.
Rich_Carlstedt
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Re: Help reading print please

Post by Rich_Carlstedt »

Lou, Besides Russel's explanation which is right on, there is also another reason for the cross-section.
Note the dimension is given for the full thread length !

When the designer wants a certain depth (as seen here) he has to spell out the details if he does not use the cross-section.( or what Russell mentioned)
That means adding text to a drawing that requires him to do more work and it would then say for example
" Drill # 32 drill ( 3mm) to a depth of 3/8" and then full thread tap BA #4 to a depth of 3/16"
With CAD, It"s easier to show the view and not worry about Text fitting into the drawing.

have fun with your Pump
Rich
LouStule
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Re: Help reading print please

Post by LouStule »

Rich_Carlstedt wrote: Tue Aug 31, 2021 10:04 pm Lou, Besides Russel's explanation which is right on, there is also another reason for the cross-section.
Note the dimension is given for the full thread length !

When the designer wants a certain depth (as seen here) he has to spell out the details if he does not use the cross-section.( or what Russell mentioned)
That means adding text to a drawing that requires him to do more work and it would then say for example
" Drill # 32 drill ( 3mm) to a depth of 3/8" and then full thread tap BA #4 to a depth of 3/16"
With CAD, It"s easier to show the view and not worry about Text fitting into the drawing.

have fun with your Pump
Rich
Thank you for this. This does make sense now.
LouStule
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Re: Help reading print please

Post by LouStule »

Thanks to all. The reason I asked is because here, on a different part, the operation is almost identical but the draftsman did not use the "cut-away" view. Perhaps because a depth of thread is specified? Just wondering why the difference. I have never seen this before on Stuart Turner prints that I can recall.
IMG_0892.jpg
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Bill Shields
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Re: Help reading print please

Post by Bill Shields »

Personal choice... orbecause he did the cutaway once decided it was not needed again...or he just missed it.

Not like it was done with a computer and easy to change.

A part of being a machinist is being able to visualize the intent of the drawing. Granted...the better the drawing the less left to interpretation.. but welcome to the real world.
Too many things going on to bother listing them.
LouStule
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Re: Help reading print please

Post by LouStule »

Bill Shields wrote: Fri Sep 10, 2021 5:29 am Personal choice... orbecause he did the cutaway once decided it was not needed again...or he just missed it.

Not like it was done with a computer and easy to change.

A part of being a machinist is being able to visualize the intent of the drawing. Granted...the better the drawing the less left to interpretation.. but welcome to the real world.
The only real difference between the two that I can see is the second one specifies a depth of thread. I've built several Stuart Turner kits and believe it or not, sometimes the dimensions given result in an unusable part. (It won't fit). I've learned over the years to double check everything and be careful with the order that you machine the parts or you may be making some of them over to slightly different dimensions than is shown on the print. Real world.
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