Longboard press molds


#1

I’m somewhat new to sketchup and I’m designing a set of molds for bending veneers, specifically, a longboard. I’ve created the bottom and would love to know if there is an easy way to create its mate for the top. I’m looking for the process since the image below may not be my final shape. If you can’t tell from the photo, it’s a complex curve (think: pringles chips). Many thanks in advance.


#2

Since your profile says you have the Pro version, the simplest way would be to make the bottom a component, verify that it is a solid (and fix as needed so that it is), then create another rectangular box, make it a Group and use the solid tools to subtract the bottom. Since the bottom is a component, you will be able to fetch another instance from the component window (subtract will erase the one you used for the operation).


#3

Thanks @slbaumgartner! I’m not sure why it said I have the pro version. I only have the free version. Am I out of luck as far as an easy version?


#4

Ok, failing the solids tools, try this:

Orbit into a side view of the base. If the base is a Group or Component, open it for edit. Use a left-to-right select to capture all the geometry that makes up the top surface of your base. Invoke Copy on the selection. Close the Group or Component, hide it, and then invoke “Edit->Paste in Place”. This should give you a copy of the top surface of your mold. Build the other half on top of this pasted surface by drawing lines up to the corners of a rectangular top face and then joining them with edges. Then make a Group or Component of the top mold.


#5

You sir, are genius! That worked perfectly! Thank you @slbaumgartner! That process is going to carry over to so many projects!


#6

Shouldn’t the profiles of the top and bottom bending forms differ by the thickness of the materials meant to be clamped/formed between them?


#7

Good question! Any ideas about how to accomplish it? Sounds like something Fredo must have attacked…


#8

I did a move copy upward of the lower half and then a center scale to mirror it. Delete the upper face and inner edges and rotate it 180* ( Forgot that part!!) A left to right selection of the complete upper edge, then move /Auto folded it downward. This will let you create the depth or thickness of-for the veneer to be pressed, depending on how much you lower the edge. Then just intersect it with a rectangular face. I just push-pulled+Ctrl`ed the inner bulge upward to clean it up. It is a fast and crude example…

SAMPLE.skp (199.8 KB)


#9

Will that work if the bottom mold is convex or combined concave+convex?


#10

Fredo’s Joint Push Pull would do the trick I’d think.

Given the task and based on my experience in commercial millwork, I wouldn’t bother with the top form.
Layup the stack of thin veneers on a top or bottom form and put it in a vacuum bag.

~14 psi doesn’t seem like much pressure until one calculates the total over the area of the piece.
A vacuum bag will definitely crush the Pringles; the form if it’s not exceptionally sturdy and it’ll reduce a 1967 Chevy Caprice to convenient carrying size if you choose to throw it in the bag too.

A quick Google Search found this…


#11

SAMPLE1.skp (271.4 KB)

This is a better example and for me it is practice! If you vacuum bag it as Geo mentioned the top is not needed. How they bond carbon fibers and bake. But to cold press or a stamping- hubcaps, cookware-pots, license plates this will give the reverse side of whatever convex // concave effects you apply. What ever you do to the bottom is reflected into the top.


#12

Waiting on my laundry to dry, this is with some dents I put in the bottom before the move/ copy. Just turned on hidden geometry and used move tool on some points. It can be text or any shape and reflected to the top. This was more fun then folding laundry will be…see yah!! and …Peace…


#13

Still a bit confused…if you need to shrink the top mold to go inside a concave bottom, don’t you need to stretch it to go over a convex bottom? And then how to mix shrink and stretch at the same time when the bottom shape has areas of both?


#14

Thanks @mrwmrutski. I like the idea of a vacuum press. I need to process all the ideas you guys are throwing out. :smile: Guess I’m newer than I originally thought.


#15

With Geo`s mention and it helped me re-call a Modern Marvels episode. Whether carbon fiber/fiber glass/veneers or corrugated layers. the vacuum not only applies the pressure on materials and form. The removal of air allows complete penetration for glue or resin into materials fibers. Then heat, ultra-violate or even ultra-sound is used to speed up or activate catalyst to harden. …Peace…


#16

Sometimes I take a question too literally! The guys are absolutely right that a vacuum press is the way most people would form something like this today, but that answers the implied question “how would you fabricate this” instead of the question “how would you draw this in SketchUp”. I was looking at a tree, not the forest.


#17

sbaumgartner—

You understandably want to know the proper way to accommodate the veneer stack, and Joint Push Pull is the way to offset a curved plane by a specific amount.

However, since you also said you want to make a form for squeezing a stack of veneer, you should realize that with such gentle curves as you have drawn, the difference in gap between the surface and its offset mirrored copy is less than the variation of thickness across the width and length of your veneer stack— probably less than the variation in a single leaf.