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I'm using blueprint data in conjunction with imperial units to, hopefully, create 3D models of machine parts, which I will later attempt to fit together.

Beginning with an eccentric shaft, I input the measurements and ended up with a horizontal cylinder purportedly to scale. Next, for the first key-way, I input coordinates to create a single vertex along the apex line, subtracted then to create another, and finally measured out from the center to create a rectangular box of, again, purportedly correct dimensions.

My next step was to create a vertical cylinder in order to divide and give me the key-way's rounded edges, sort of like a makeshift cutting tool.

Again, using a bit of math I created a cylinder with a diameter shown to be the same width as the key-way, only it clearly isn't.

The cylinder plunges down with extra mass spilling beyond each of the key-way's sides, and yet, again, taking account of the measurements as reported, they should be exactly the same; it should fit precisely, with no visible variance beyond some minute thousandth's discrepancy.

Am I missing something? Clearly, yes, but my question to you, is what might I be doing wrong, and how to go about correcting the issue.

David
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Russell Hall
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    Hello and welcome. Could you please add some images illustrating your scene? Some images would go a long way in helping understand what seems to be a complex scene. Please edit you question and provide some screenshots showing the objects, the discrepancies, scene settings like units, object scale, and dimensions, any modifiers used, or other relevant data. Signed: Odd European sort – Duarte Farrajota Ramos May 22 '17 at 17:28
  • Maybe related ?: https://blender.stackexchange.com/questions/47318/why-do-the-measurements-of-this-object-seem-erroneous/47320#47320 –  May 23 '17 at 02:52
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    You didn't choose the best software to combine with your prejudice. Check top 30 Blender developers: https://www.blender.org/development/the-top-30-blender-developers-2016/, also Blender Foundation is based in Amsterdam, Netherlands. If you have any doubts about flags or downvotes check StackExchange help page: https://blender.stackexchange.com/help/be-nice. – cgslav May 23 '17 at 13:33
  • PS a flag does not take your rep, especially here in your case since rep can never go to a negative number. – David May 23 '17 at 14:18
  • Right, thanks for the helpful insight on rep and flagging, David. And kudos to everyone out there fighting the good fight, ensuring that questionable references like "intercontinental travel," and "funky currency" are appropriately sanctioned. allow me to apologize by stating unequivocally, however ironically, that I agree with you wholeheartedly--bigots should know their place, which is rooted out and stamped from existence as far as I'm sure we all need to be concerned, and anyone who flags that is merely forwarding the cause of bigotry in general. Now, having cleared the air, any ideas? – Russell Hall May 23 '17 at 16:36

1 Answers1

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I had to ask Google what a key-way was and how it differed from a key-seat.

In my example the shaft has an outer diameter of 20mm and an inner diameter of 10mm and a length of 100mm. The key-way is set to fit a key 6mm wide and 5mm thick.

A simple way is to create the cross section of the shaft and then extrude to length:

1: In Front view, Object modeand Cursor at Center, Add a circle mesh with 32 vertices and a radius of 10mm. (to enter these parameters look in the Last Operator panel at the bottom of the tools panel or hit F6 to open same panel as a popup ).

Tab into Edit mode and Add a circle with a radius of 5mm. Then Add a third circle with radius of 7.5mm. (Inner radius + half the thickness of the key).

2: To fill in the faces between outer and middle circles select both circles and hit the W key to open the Specials menu and choose the Bridge Edge Loops Option.

Repeat for middle and inner circles.

3: Select vertice “A” and Extrude 3mm along X axis. (E X .003) Select again only vertice “A” and Extrude 3mm in the negative X axis. ( E X -.003)

These two new vertices need to be extruded down along the Z axis until they intersect with the inner circles edge. To do that we need to enable Snapping to Edge. see image 3.

4: If you haven’t already, zoom in on this part of the mesh. Select both vertices “B” and “C” and Extrude and drag the new extruded vertices down in the Z axis until they snap to the inner edge.

This can be a little tricky to get right. What you need to do is E (to extrude) Z (to confine movement to the Z axis) and then hover your mouse over the edge you want to snap to. A little orange circle will appear to show when and where the vertice is snapped to the edge.

Don’t forget to Disable the Snapping tool when you are finished with it. enter image description here

5: Select the and Delete the 5 highlighted vertices.

6: By selecting 4 vertices at a time fill in the missing faces (F) where the key-way will be.

7: In Edge select mode select both the inner and outer edge loops (Shft Alt Select each loop).

8: E Y 0.1 validate, to create a shaft 100mm long. enter image description here

3fingeredfrog
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