Laser cut acrylic case in sketchup and DXF*based on tayken's

Standard PCB templates and project cases

Laser cut acrylic case in sketchup and DXF*based on tayken's

Postby arakis » Wed Jan 18, 2012 9:29 am

here are some sketches in sketch-up and the accompanying DXF files...and some renderings of a case designed on this template...
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caseWOsides.jpg
case exploded.jpg
caseclsed.jpg
3.1X5template.rar
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3.1x5Template.jpg
best regards FIlip.
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby tayken » Wed Jan 18, 2012 10:04 am

Wow! 3.5 mm for the slots is kinda big. My design used 3 mm acrylic for all parts, so these slots were 3 mm. Also I used 3 mm holes for screws, metric size does not have a screw with 3.2 mm diameter also the laser width makes the hole a little larger so it is not so tight fit. Other than that it seems good.

Guess I have to start learning and using sketch-up. It will be better for sharing designs I guess. Also I'll try to come up with an automated script or sth that can design the parts for any size we enter.
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby arakis » Wed Jan 18, 2012 10:15 am

nice, IO left .5mm clearance so it would fit 3mm acrilic into it, bt it would be better if you say 3mm is ok... I'll make the changes tomorow...

here is a IRtoy rendering with the case(without the sides, I used 2mm and 7.5mm standoffs (the numbers I chose arbiterly so its not stuck to that

I find that skecthip is much faster then any other drawing/3d modeling software out there.. I tried solidWorks and autocad inventor, but both are much more cumbersome to work with, sure you can do much more complicated designs with them, but for 99% of the stuff we are gonna need sketchup is more then enough...
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USB_IR_Toy_V2.jpg
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby tayken » Wed Jan 18, 2012 11:45 am

arakis wrote:nice, IO left .5mm clearance so it would fit 3mm acrilic into it, bt it would be better if you say 3mm is ok... I'll make the changes tomorow...

Usually what happens is that because of the beam width, some material gets removed, which messes up with the dimensions you have initially designed for. For the laser cutter I've used, this was 0.2 mm, so all slots should be 0.2 mm smaller. I'll verify that next time I use the laser cutter to try out one of the box designs, probably sometime next week.

arakis wrote:I find that skecthip is much faster then any other drawing/3d modeling software out there.. I tried solidWorks and autocad inventor, but both are much more cumbersome to work with, sure you can do much more complicated designs with them, but for 99% of the stuff we are gonna need SketchUp is more then enough...

I'm used to SolidWorks as all my uni life revolved around it somehow. But one other reason for SketchUp is that we want others to use our designs: if we use SolidWorks, people will use the pirated version + we have to get a license (which is expensive). SketchUp is free, anyone can download it.

I had to prepare some parts for SolidWorks like hex spacers and other things for this. I'll create them for SketchUp and add them to SVN if there are no such libraries. I'm trying it out now, kinda fun to use. :)
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby dsm » Thu Jan 19, 2012 3:15 pm

minor comments

I would be concerned about the how thin the sides of the slots are in the top and bottom acrylic windows.
I suspect roughly 1.5x to 2x the thickness of acrylic would be a better choice.
Multiple small slots and tabs (say, 10 mm each) would be better than one big slot [2] and tab [1].
The thin "ears" on the side walls look fragile and overly fussy - just a simple butt joint would be more robust.

I tend to think that the 3.0 mm acrylic looks a bit clumsy, especially for the smaller boards.
Would you be willing to take a pass at your design using 1.5 mm acrylic for comparison?

Thanks for your time.

dsm

[1] For example, the long sides would be
    50 mm => 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab
    60 mm => 5 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 5 mm space
    70 mm => 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab
    80 mm => 5 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 5 mm space
    90 mm => 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab
    100 mm => 5 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 5 mm space
and the short sides would be
    31 mm => 10.5 mm space + 10 mm tab + 10.5 mm space
    37 mm => 3.5 mm space + 10 mm tab + 10 mm space + 10 mm tab + 3.5 mm space
    43 mm => 6.5 mm space + 10 mm tab + 10 mm space + 10 mm tab + 6.5 mm space
    49 mm => 9.5 mm space + 10 mm tab + 10 mm space + 10 mm tab + 9.5 mm space
    56 mm => 3 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 3 mm space
    62 mm => 6 mm space + 10 mm tab + 10 mm space + 10 mm tab + 10 mm space + 10 mm tab + 6 mm space
[2] When I've made acrylic cases like this before, I've found it easier to make the tabs as specified and then modify the slots to fit the tabs modulo the laser kerf width.
Last edited by dsm on Thu Jan 19, 2012 7:07 pm, edited 5 times in total.
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby dsm » Thu Jan 19, 2012 4:23 pm

corner radius

From a design language viewpoint, it might be nice if the corner radius of the top and bottom acrylic windows matched the corner radius of the boards (4.0 mm).

Thanks for your time.

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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby tayken » Thu Jan 19, 2012 9:21 pm

dsm wrote:I would be concerned about the how thin the sides of the slots are in the top and bottom acrylic windows.
I suspect roughly 1.5x to 2x the thickness of acrylic would be a better choice.

That concerned me too, I'll get to that when I revisit my model.

dsm wrote:Multiple small slots and tabs (say, 10 mm each) would be better than one big slot [2] and tab [1].
The thin "ears" on the side walls look fragile and overly fussy - just a simple butt joint would be more robust.

I was thinking the same thing. Actually I was working on some type of function to give me those tab and slot lengths, your following formulas are great, I'll use them!

dsm wrote:I tend to think that the 3.0 mm acrylic looks a bit clumsy, especially for the smaller boards.
Would you be willing to take a pass at your design using 1.5 mm acrylic for comparison?

I have access to 3 mm acrylic easily here, 1.5 mm is not available, but I can quickly adapt it to 2 mm. I'll try to reserve the laser cutter for next week so that I can try out the designs.

dsm wrote:From a design language viewpoint, it might be nice if the corner radius of the top and bottom acrylic windows matched the corner radius of the boards (4.0 mm).

Initially the corner radius was something smaller for the boards. That will be changed to new radius.
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby ian » Fri Jan 20, 2012 3:53 am

Thanks dsm and Tayken, this is great feedback. Your experience is going to make the v1 case so much nicer, thank you.
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby arakis » Fri Jan 20, 2012 4:28 am

I have a comment on the corner radius, it has to be smaller then the board corrner radius so as not to go over the sides. there is only 1mm space between the border line and the side panels, so the corner raduis is limited to 1mm, the side plates create a box and would be sticking out if the corrner radius is larger...
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby ian » Fri Jan 20, 2012 4:39 am

I think on Taykens prototypes (that I had made) the sheet is bigger and the sides stop short. The top and bottom over-hang the sides.
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby ian » Fri Jan 20, 2012 4:42 am

Here is a pic of the prototypes BTW:
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby tayken » Fri Jan 20, 2012 6:35 am

arakis wrote:I have a comment on the corner radius, it has to be smaller then the board corrner radius so as not to go over the sides. there is only 1mm space between the border line and the side panels, so the corner raduis is limited to 1mm, the side plates create a box and would be sticking out if the corrner radius is larger...

In the original topic, I included one of the pics from my CAD program. Here it is again. As you can see, this is not a problem. Radius here was smaller, 2.775 mm, but I changed the designs to 4 mm on my files, corner radius is not a problem.
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby dsm » Fri Jan 20, 2012 7:11 am

internal margin

tayken,

One additional suggestion since you're still at the modeling stage.
How about adding a small margin (perhaps 0.2 mm in length and 0.2 mm in width) to allow the boards to vary slightly from their intended dimensions? If the board edges are routed perfectly or bit small, no problem. If the board edges are routed a bit large, something needs to be reworked.

For example, I've noticed that the long sides of my Bus Pirate v4 (for developers) board are fairly smooth so the board width is close to the expected dimension, while the short sides of the same board are somewhat rough so the board length is slightly larger than the expected dimension.

Thanks for your time.

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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby ian » Fri Jan 20, 2012 7:14 am

In Filip's sketchup version I think we left 1mm or so per side.
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Re: Laser cut acrylic case in sketchup and DXF*based on tayk

Postby tayken » Fri Jan 20, 2012 7:42 am

dsm wrote:One additional suggestion since you're still at the modeling stage.
How about adding a small margin (perhaps 0.2 mm in length and 0.2 mm in width) to allow the boards to vary slightly from their intended dimensions? If the board edges are routed perfectly or bit small, no problem. If the board edges are routed a bit large, something needs to be reworked.

I was thinking about the same thing a few minutes ago. :) I'm guessing 0.5 mm on each side will be enough for this.

Also I am planning to fix the distance between slot edge and piece edge. You stated that 1.5 times the thickness is a good measure for that. I guess I'll use that.
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