# Modeling an Airbrush Live!

Um, no. I would like to see your knurling chops too…

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OK. Here goes.

So to draw the diametral knurling, I determined the number of diamonds I wanted around the circumference. There are forumulas to calculate this stuff when setting up a knurl (the tool to make the knurling) in the machine shop. Since knurling only displaces the metal, the overall dimension of the part is slightly larger than the blank and I took that into account here.

In this example I wanted 48 diamonds around the circumference and the starting diameter is 0.5 so I drew a 96-sided circle with 0.25 radius. Then I used Offset to create a larger circle which is at the height of the peaks of the diamonds. The vertices on the circles guide the layout for the width of the diamond. I added guidelines in the screen grab above that run through the vertices on the circle. The center one goes through a vertex on the outer circle and the other two go through the next one up and down on the inner circle.

I also figured out how long I wanted the diamonds to be and drew the diamond you see at the edge of the circle and made it a component.

Next, I rotate/copied the diamond and then moved it to make one for the second row, on the right, above.

I used Rotate/Copy to make 47 additional copies of the diamond components and them Move/Copy to make a whole bunch of them down the length.

Side note: Since the diamonds are components, it’s trivial at this stage to put the flat tops on them like Aaron has on his airbrush. You only need to edit one instance and it done.

After the diamonds are finished, I exploded the components and then used Intersect Faces to intersect them with large circles drawn near each end. This resulted in a solid component which is important later on. Note that you have to get the geometry of the first diamond correct so that all the edges come together properly so the early setup needs to be right.

To show the knurling running out on the tapered shaft like on the tap wrench handle in my earlier post, I first added a circle on the end of the knurled component and pulled it out with Push/Pull. Modeling this sort of thing centered on the origin with an axis line running through the center makes this sort of modeling easier since you can’t infer the center from the end of the component.

I drew a shape with a tapered hole that matches the taper of the shaft. It runs off the part some way into the knurling. I made that shape a solid component and then use Trim from Eneroth Solid Tools ( BoolTools2) to cut down the shaft.

I repeated the process to put a small chamfer on the opposite end.

Probably sounds really complicated but it took longer to type this than it did to model it.

And the end result.

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That’s some ninja skills there… love it.

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Thank you.

I think I finally understand!

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Understand what? That I like to make overly detailed models? I’m a little OCD with the details?

Easy enough to add a dome at the end, too.

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That’s brilliant Dave!

Apologies for the late reply. Away for the weekend at the moment.

Very helpful tutorial which I’ll give a try when I get home.

Thank you.

Mike

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Thank you sir.

By the way, even if you don’t need to draw knurling in your projects you might find the general idea useful for other things. Here I was monkeying around with the model. the helical stripes were trivial with this setup thanks to the use of components.

As a general principal, @DaveR is mostly showing a methodology that comes from how you actually make the thing. What could be more natural than that? Machining things is mostly a matter of starting with some solid material, and then using a lathe or mill to cut away material to produce the final result. So, create a solid object that represents the shape of the tool used for cutting swept through the total range of movement that it goes through, and then subtract that solid from the original material. Of course, it helps to be familiar with how a machinist actually does make the stuff.

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Thank you Dave

I’ll have a play with this. Like you say, the method will be useful for other things beside Knurling.

Hope you’re having a good week.

Mike

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