# SO3 XXL: Golden Ratio Threaded Inserts

Thinking ahead to how I’m going to drill holes for threaded inserts in my wasteboard. I really like @WillAdams design here (Will, let me know if you have thoughts given how old that post is): http://www.shapeoko.com/forum/viewtopic.php?f=37&t=5984&start=20#p46292

But what I don’t know how to do is expand that design to cover the entirety of the XXL wasteboard (I’m ok with drilling outside of the millable area).

Is there an easy way to do the calculations for hole placement like this?

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I would just draw it up in a drawing program such as Inkscape.

• draw in the diagonals
• draw the initial circle
• clone the circle in place
• scale it by phi
• repeat

Then, clone all the parts and use path operations to create points which you can snap to so as to place the drill points. Then clone all the drill point circles and scale each in place to make the countersink hole.

Only do the centered placement if you actually think you’re going to be doing mirrored / flip jig type things — it seems a nuisance otherwise — alternately put the centerpoint for the geometry at the origin point (slightly inset to allow sufficient structure to hold things in place), or centered at the front of the board.

Only do the centered placement if you actually think you’re going to be doing mirrored / flip jig type things — it seems a nuisance otherwise — alternately put the centerpoint for the geometry at the origin point (slightly inset to allow sufficient structure to hold things in place), or centered at the front of the board.

Thanks Will. Unfortunately, not sure I understand your point about centered placement…I do plan to do two-sided milling.

I chose to put the center of the design at the center of the wasteboard, so as to facilitate flipping of parts for two-sided cutting — if you’re not doing that, then put it at a corner.

Might be a good idea to put the origin at the front-center — I’m still debating on what I’ll do when I get the XL upgrade.

Gotcha. thanks for the clarification.

I’m curious how I should deal with the 2-part wasteboard supplied by C3D…I planned to put the threaded inserts into the supplied wasteboards, then drill a matching set of holes in the spoilboard and mount through those holes. But with the gap in the wastboards, not sure how to deal with the center column of holes…

Also, sorry if I missed it…how do you determine the size of the initial circle?

The initial circle should be just larger than the shortest dimension of the smallest stock which you are planning on using, plus the reach distance of your clamps.

Yeah, the two-part wasteboard is potentially a pain.

I also didn’t like the idea of having the threaded inserts at the bottom of the layers — worried about them falling out, but that’s probably not an issue.

Big thing when drawing up the hole placement — also draw in the structure of the machine, and plan so as to be able to locate fasteners appropriately, and keep track of which fasteners go in from the top.

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Regarding them falling out…I was thinking about only drilling holes in the spoilboard large enough for the threaded bolts to fit through…this would essentially “sandwich” the lip of the threaded insert between the countersunk hole in the wasteboard and the bottom of the spoilboard.