Scaling a design

[Soren Christensen]

Hi guys,

Well as the topic says, this is about scaling and which is my current issue.

I have a design for a hanging pendant lamp, which i wanna scale, for the ability to make different sizes of it. However thats where im stuck.
The original design was made for 4mm material. But i wanna make sure I can use 3mm and also thinner materials.

Do I have to redo the whole thing, for each thickness?

Or is it possible to have a way to scale it, so one makes sure it will fit for the various material thicknesses?


Im waaay out of my depth here, so I would appreciate any help

Attached a sample of one part. And marked the place, where I need the measurements to remain the same, while scaling the rest.

[Kim McIntosh]

Hi Soren,
No way to do it easily unfortunately. You can decrease the size from 4mm to 3mm but the overall size needs to be 0.75 smaller. I recently did a large wooden animal head that used 3mm material. I reduced the size by half and had to change several hundred slots. A lot of work but only has to be done once .
Cheers

[Glen Monaghan]

If you don't want to redo the whole thing, you would need to use a parametric design tool. Such a tool allows you to specify and/or constrain certain parameters (hence the term "parametric") of various design elements, such as keeping the depth of each gear tooth a fixed size as the gear is scaled larger. As another example, if you wanted to keep the spacing between teeth constant, would be to automatically add teeth when the tooth width exceeds some while threshold scaling up the gear. More common design tools such as CorelDraw don't inherently have that parametric ability, although there are rather cumbersome ways to more-or-less deal with it in some situations. You would be better off trying something like OnShape, the relatively new and reasonably approachable online parametric CAD tool.

[Rich Harman]

Like Glen says, you need a parametric tool to do that. I would recommend AutoDesks' Fusion 360, it is free and can easily do what you need. OnShape is very similar. I have not kept up with OnShape since I don't use it but the deciding difference for me was that OnShape only works with an online connection. Fusion 360 does too, but it also has an offline mode.

I spent a couple minutes browsing OnShape's website. I did not notice anything there that Fusion 360 couldn't do, but I did notice that there seems to be a lot more features/capabilities in Fusion 360 (none of which would matter to solving the OP's scaling issue). I also noticed that the paid version for OnShape is more than double what Fusion 360 is. OnShape must have some advantages, I'd be curious to hear what they are.

This is quoted from OnShape's webpage - the free "Hobbyist" version;

"With all of your CAD documents visible to the public and available for copying..."

Yikes! Apparently you need a paid subscription to keep your designs private. If that is not the case then I think they did a very poor job explaining how secure one's designs would be.

[Kev Williams]

Another reason I keep my ancient Casmate around- It has a function called 'circular multi-copy', which would work good for this...
This is a 28 year old DOS program, and I just hand-drew this just to show how it works... took me about 10 minutes total
first I drew a segment, then chose circular multi copy--
cs1.jpg

told it I wanted 40 copies, which it piled up as shown
cs2.jpg

I expanded them out and hit OK, they're too far apart,
so I hit undo, and resized them in a bit, 2nd try not bad-
cs3.jpg

zoomed in, they're not the least bit squared up, just a sample
I exported as DXF, now they're in Corel, and you can see
the segments aren't connected-
cs4.jpg

I used the 'close path' function, and they all connected!
then I drew a circle inside, combined, and it painted!
(had the segments not connected, only the inner circle would have painted)
cs5.jpg

So now I know the 'close path' will work! And I actually drew the segment wrong, what I should have done was draw the cavity instead of the 'tooth'- So I went back and did just that. I removed the 'tails' and made the top open, so now it was only a slot. I again made 40 copies, only this time I specially moved segment to "0-0" and entered a 0"x / 3"y coordinate to create a 6" diameter 'gear', (lower left in the next pic), SAVED it, then did an 'undo', then entered a 0"x / 5"y coordinate to create a 10" gear (upper left)-- I exported those into Corel, made copies and moved them to the right as shown, then put "close path" to work.
Worked perfectly! Because I kept the center X coordinate at 0, the slot and subsequent slots squared up as they should.
Note where I connected the gears together, both diameter gears have 40 identical sized slots!
cs6.jpg
Now all that's needed is to insert the 'spokes' or whatever design within the middle is needed!

Within 40 minutes using a 28 year old vinyl signmaking program I made a messed up trial version followed by a good version that left me with a template to make ANY diameter circle with the exact same slot-size, within a couple of minutes... . I HAVE to believe that somewhere out there is a similar circular-copy program. Where to look is the question?
>edit< -- maybe that Auto Fusion Rich mentioned will do the trick?

[Glen Monaghan]

Mayhaps I read more into the OP's question, but I think he was looking for a more general solution that would allow an entire design to be scaled while keeping certain features "fixed", not simply how to scale up or down a gear shape with fixed spacing between teeth. I'm pretty sure you can accomplish the same, or a very similar, process as what you used, Kev, in CorelDraw and Adobe Illustrator but, for the more general solution that doesn't require manual intervention throughout the design every time you want to make changes, you need a parametric design tool like Onshape or Fusion360. Consider, for example, creating a slot and tab design for a box or dollhouse. In order to change material thickness (for example, from 3mm baltic birch to 1/4" MDF), you need to change all the slot widths accordingly without altering slot or tab lengths. However, to change the overall size (such as to make the object 30% larger) while still using the same material, you might want or need to change the slot and tab lengths but without altering slot width. These are the sorts of things that, at best, are tedious to do manually but parametric tools excel at.

[Lee DeRaud]

Mayhaps I read more into the OP's question, but I think he was looking for a more general solution that would allow an entire design to be scaled while keeping certain features "fixed", not simply how to scale up or down a gear shape with fixed spacing between teeth. I'm pretty sure you can accomplish the same, or a very similar, process as what you used, Kev, in CorelDraw and Adobe Illustrator but, for the more general solution that doesn't require manual intervention throughout the design every time you want to make changes, you need a parametric design tool like Onshape or Fusion360. Consider, for example, creating a slot and tab design for a box or dollhouse. In order to change material thickness (for example, from 3mm baltic birch to 1/4" MDF), you need to change all the slot widths accordingly without altering slot or tab lengths. However, to change the overall size (such as to make the object 30% larger) while still using the same material, you might want or need to change the slot and tab lengths but without altering slot width. These are the sorts of things that, at best, are tedious to do manually but parametric tools excel at.

Sorry if I'm a bit late to this particular party...
Assuming there is a "base" drawing with the slots added after-the-fact as rectangle primitives, this may help:
ResizeSlots.zip
It's a VBA macro for Corel that sweeps the current selection looking for rectangles. If one of the rectangle's dimensions matches a specified value, it changes that dimension to to a second specified value. So you can just rescale the drawing, find one of the slots to determine its new width, and use the macro to change all such slots back to the width that matches the material thickness.

(I forget where I found the original...I modded it to find rectangles buried within groups, and also handle rotated rectangles properly.)

[Toby Fletcher]

Hi

Unless the new thickness isn't an exact divisor of the circumferences of the part there's not really a way around doing a redesign.

However for a free and relatively easy general solution it may be worth checking the pattern around a path function in Inkscape:
https://logosbynick.com/inkscape-pattern-along-path/

Kind regards

Toby