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Last week I had an e-mail conversation with a fellow who has been doing a bunch of 3D printing. He is working on an adaptor for something in his shop and wants to print a threaded part. He was looking for a way to draw the threads in SketchUp. I played with several methods for drawing these. Some of the methods got to be quite convoluted but I finally hit on something I think works well with relatively little fuss. It might still be a little tedious in spots but if you make use of components, you’d only need to draw the thing once. Just make sure you save the components for later use.
I used three plugins in this video. They are, in order of appearance, Draw Helix, Upright Extruder and Solid Inspector. Draw Helix is no longer available but you can use the Helix tool from Curve Maker. These are all available through the Extension Warehouse so if you are using V2013, 2014 or later , you can download and install them automatically under Window>Extension Warehouse.
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Following your instructions, if you use the helix to upright extrude a plane whose face equals in dimension the diameter of said helix (to create a solid double helix or archimedean screw, as in: http://i1006.photobucket.com/albums/af181/Tarma_photo/Ne%203D%201mage/Archimedes-screw_two-screw-threads_3D-view_animated1.gif - but without the center cylinder piece -, think of it as a solid DNA chain, a toboggan), then upright extruder will invariably produce errors and strange artifacts. In fact if the plane is equal or larger than the radius of the helix, these artifacts and errors will always appear.
Is there a way to avoid this?.
Is there an alternative, another way to create this archimedean screw? (without the center cylinder depicted in the sample).
There's a SketchUp file that shows and exemplifies what I mean, here:
A final comment from me in this series: sorry to have used such an unfriendly screen name - I've only just discovered how to change it from the Fine Woodworking default user-2364299 to my own initials JohnWMcC.
Let's hope this comment comes through with the new name.
And as a further refinement, when making the component, or using it in a model, one can set it to Glue to Any face, align the component axes at the centre of the screw head, and have the screw align itself to the face you want it to 'screw into'.
Here's another link to a screenshot of several screws in a frame joint, in SketchUp X-ray view:
Further to my previous comment, here's a link to a screenshot of what the drawn screw looks like in SU.
I remember seeing an earlier blog, Dave, in which you discussed drawing woodscrews for detail woodworking furniture drawings, but I can't now find it. If this comment belongs better there, perhaps you could move it?
I've been experimenting with a quite different way of drawing them, using a PNG image of a woodscrew with transparent background, and putting it on a face with hidden edges, making that into a component, and setting it as 'always face camera.'
I combined this view of the thread with a separate component of a drawn circular top, on which one can draw either a cross head (UK pozidriv or US Phillips) outline, or a slotted head.
I used only 12 segments for the circle round the head, to minimise the poly count. At the scale one views a complete furniture item, this looks smoothly round.
The resulting component file is only 26Kb even including the texture. Adding multiple copies of the screw component adds little further to the total drawing size - even adding 100 copies only increases the file size by a further 24Kb.
Here's a link to the SketchUp file for a sample screw. It can be adjusted in length by enlarging or shrinking the length of the rectangle containing the thread image, or by overall scaling.
Excellent, Matt! That's always my hope.
Dave, even though I have no need to be able to draw anything like this, there are still a lot of great tips that will come in handy. Thanks for the great tutorial.
Thank you Alex.
As for the dimensions and angles, they came from tables and formulas I found by searching for 'Acme threads.' There is a great deal of information about them available. The 29° angle is used for American Standard Acme screw threads but 30° is used for metric Acme threads.
Thanks Dave, This has been invaluable. Compared to other tutorials regarding thread making,this is a credit to your teaching style (and knowledge of Sketchup). I noticed you used a 29 degree angle on the acme threads and your guide points were .0741" up on the blue axis and .11" left on the red axis (relative to the "bottom end" of the helix). Where did these numbers come from? Is there a formula or basically trial and error? Great job, Alex.
Carl Swensson's woodworking skills go very, very deep. But they go wide as well.
The Shakers had this diminutive design pegged
Fast, fun approach to making a comfortable, casual seat
In this video Michael finishes the first of the three boxes. Gluing-up, planing, sanding and finishing bring a new piece of art to the world.
In this video Michael starts work on the second box, a carved and painted Saddle lid box.
Michael begins carving the saddle lid box with his ripple pattern along the top. Then turns to his 5/30 gouge to texture the sides of the box. This isn't work…
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