Standoff size and side height

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Re: Standoff size and side height

Postby ian » Tue Feb 28, 2012 2:46 am

I did not realize shapeways is in Eindhoven! I will try to make a visit.
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Re: Standoff size and side height

Postby tayken » Tue Feb 28, 2012 4:46 am

I liked the idea of replacing spacers with nuts.
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Re: Standoff size and side height

Postby dsm » Tue Feb 28, 2012 6:23 am

comments

tayken wrote:I liked the idea of replacing spacers with nuts.

I really hope you're kidding me, because if you're serious, then I'm going to seriously regret even mentioning the idea. :)
Assembling an enclosure based on the "nuts as spacers" idea is not my idea of fun. Dis-assembling and re-assembling
the enclosure every time you want to tweek the firmware seems like it would constitute a serious pain in the ass.
Adding openings for all the connectors and push-buttons so that you can tweek the firmware without opening the case seems like a good way to weaken the enclosure (swiss cheese comes to mind). Cheap is nice, but most people are not that hard up for cash.

Other than Scheme G (with or without side walls), my current favorite enclosure is the modular open case design (link).

Thanks for your time.

dsm

proposed new motto - Friends don't let friends build enclosures that use "nuts as spacers"...
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Re: Standoff size and side height

Postby tayken » Tue Feb 28, 2012 6:41 pm

dsm wrote:comments

tayken wrote:I liked the idea of replacing spacers with nuts.

I really hope you're kidding me, because if you're serious, then I'm going to seriously regret even mentioning the idea. :)
Assembling an enclosure based on the "nuts as spacers" idea is not my idea of fun. Dis-assembling and re-assembling
the enclosure every time you want to tweek the firmware seems like it would constitute a serious pain in the ass.

Gotcha! :D

Hmm, actually I've been thinking a little. What we can do is something in the line of custom built spacers. But instead of using a 3D printing company, we can use off-the-shelf materials. Something like this. Nice thing about these is that people do not have to screw them on/off as with metal spacers. I'm looking for some M3 round non-tapped spacers.
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Re: Standoff size and side height

Postby tayken » Tue Feb 28, 2012 6:52 pm

tayken wrote:Hmm, actually I've been thinking a little. What we can do is something in the line of custom built spacers. But instead of using a 3D printing company, we can use off-the-shelf materials. Something like this. Nice thing about these is that people do not have to screw them on/off as with metal spacers. I'm looking for some M3 round non-tapped spacers.

Yep, they do exist: http://www.technobotsonline.com/nylon-s ... 33702.html

I guess we can ask Seeed if they know a manufacturer?
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Re: Standoff size and side height

Postby dsm » Tue Feb 28, 2012 8:15 pm

comments

tayken,

Whew, that's a relief...



About the off-the-shelf nylon spacers - nice find...
I read the description of the 4607-000 spacers as being
5.0 mm OD / 3.2 mm ID / 3.0 mm long in black nylon @ 0.83 £ for 25 units (or roughly $1.32 at today's exchange rate).
Using two spacers above and one spacer below, at each corner, the cost for the spacers would be roughly $0.63 [1].
=> (0.83 / 0.6293) x (12 / 25)
Using two spacers above and one M3 nut below, at each corner, the cost for the spacers would be roughly $0.49 [1].
=> (0.83 / 0.6293) x (8 / 25) + 0.0556 [2]

I think the more interesting part from the same site is 4607-002.
I read the description of the 4607-002 spacers as being
5.0 mm OD / 3.2 mm ID / 5.0 mm long in black nylon @ 0.85 £ for 25 units (or roughly $1.35 at today's exchange rate).
Using one 5.0 mm spacer above and one 3.0 spacer below, at each corner, the cost for the spacers would be roughly $0.43 [1].
=> (0.85 / 0.6293) x (4 / 25) + (0.83 / 0.6293) x (4 / 25)
Using one 5.0 mm spacer above and and one M3 nut below, at each corner, the cost for the spacers would be roughly $0.27 [1].
=> (0.85 / 0.6293) x (4 / 25) + 0.0556 [2]

Pros and Cons
    off-the-shelf parts can be cheaper in some configurations.
    off-the-shelf parts have a smoother surface finish.
    ----------
    3D printed parts can be cheaper in some configurations.
    3D printed parts allow you to get exactly the length you want.
The problem remains that assembly and dis-assembly using this scheme is not fun.
Cheap is nice, but most people are not that hard up for cash.

Thanks for your time.

dsm

[1] Plus the cost of the bolts and the exterior nuts
    M3.0 x 16 mm x 0.5 mm pitch zinc plated steel Phillips machine screws ~ 92005A126 ~ 100x for $2.80 ~ 4x for $0.112
    M3.0 x 0.5 mm pitch zinc-plated steel nut ~ 90591A121 ~ 100x for $1.39 ~ 4x for $0.0556
[2] M3.0 x 0.5 mm pitch zinc-plated steel nut ~ 90591A121 ~ 100x for $1.39 ~ 4x for $0.0556

[3] The prices I mention are relatively high since they are based on relatively low volume purchases.
Costs on the ground in Shenzhen will obviously be lower.
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Re: Standoff size and side height

Postby dsm » Fri Mar 02, 2012 12:50 am

Scheme G "-v2" prototype parts

The initial "-v2" top and bottom magnet holder prototype parts for Scheme G ordered 13Feb12 from Shapeways arrived back on 24Feb12. Since then I've been making measurements and running some experiments. Although these Scheme G "-v2" prototype parts were ordered before the "-v1" prototype parts arrived, they worked surprisingly well. To gain some experience with the "-v2" prototype parts, I built 3 or 4 Scheme G cases without walls and another 3 or 4 Scheme G cases with walls.

My intent is to design the various Scheme G constituent components so that Scheme G enclosures need no adhesives to hold them together. At present this is not yet the case. There are two critical dimensions to ensure this functionality...
  • The diameter of the magnet wells (under a range of SLS fabrication conditions) must allow the 3.0 mm diameter neodymium magnets to be held in place without adhesives (slight interference fit).
    Generally I found that the "-v2" top and bottom magnet holder prototype parts were slightly loose in some cases [1].
    I built a tool [2] to investigate this issue and believe reducing the diameter of the magnet well by 0.05 mm will be sufficient for the "-v3" prototype parts.
  • The diameter of the laser-cut holes in the acrylic windows must allow the one-way barb to securely and permanently capture the top and bottom magnet holders. Here there were several problems.
    First, because of the laser kerf, some experimentation was needed to ensure that the hole size in the acrylic window was correct. I do not want to have to hand drill these holes in production.
    Second, the dimensions of the retention barb ring are toward the lower end of the resolvable features for SLS parts.
    What was designed as sharp barb became a gentle "bump" around the outside of the main cylinder [1].
    The size of this feature will be increased by 0.05 mm to 0.1 mm for the "-v3" prototype parts.
    The length of the retention barb ramp length will be increased increased from 0.5 mm to 0.8 mm.
    Third, the diameter of the main cylinder of the magnet holders was slightly smaller than expected.
    Increasing the diameter of the main cylinder by 0.05 mm should take case of this problem.
In addition to the above changes, I plan to add "-v3" variant prototype parts suitable for 2.55 mm thick acrylic windows in addition to the current 1.5 mm and 3.0 mm variant prototype parts.

I also have some ideas about how to simplify the parts in order to allow them to be injection molded.

Thanks for your time.

dsm

[1] I used cyanoacrylate glue to make sure the "-v2" example cases held together securely.
[2] magnet-hole-size-test-jig

magnet-holder-size-test-jig.png
magnet-holder-size-test-jig
Last edited by dsm on Tue Mar 06, 2012 7:40 pm, edited 1 time in total.
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Re: Standoff size and side height

Postby dsm » Sun Mar 04, 2012 9:19 pm

Scheme G "-v3" top and bottom magnet holder comments

I updated [1] [2] the Scheme G top and bottom magnet holder design to "-v3" on 04Mar12 and ordered prototype parts from Shapeways which are supposed to be delivered 15Mar12.

The changes from "-v2" to "-v3" include the following:
  • magnet boss diameter was increased slightly
  • magnet well diameter was decreased slightly
  • magnet well depth was increased slightly
  • retention barb height was increased slightly
  • retention barb ramp length was increased slightly
  • variant added for 2.55 mm acrylic [3]
SoB-case-SchemeG-three-sizes-dsm-v3.jpg
SoB-case-SchemeG-dsm-v3 (three sizes)

SoB-case-SchemeG-assembled-dsm-v3-perspective.jpg
SoB-case-SchemeG-dsm-v3 ~ assembled 2.55 mm acrylic ~ perspective

SoB-case-SchemeG-assembled-dsm-v3-cross-section-orthographic.jpg
SoB-case-SchemeG-dsm-v3 ~ assembled 2.55 mm acrylic ~ cross-section ~ orthographic

Thanks for your time.

dsm

[1] The initial "-v1" top and bottom magnet holder prototype parts for Scheme G (used for the above DP6037-size enclosure prototypes) were designed for 1.5 mm acrylic windows and had a retention ring (0.05 mm high by 0.5 long) scheme.
[2] The redesigned "-v2" top and bottom magnet holder prototype parts have a one-way barb (0.15 mm high by 0.5 mm long).
[3] The 1.5 mm and 3.0 mm acrylic variants already exist.
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Re: Standoff size and side height

Postby dsm » Sun Mar 18, 2012 1:48 am

Scheme G "-v3" prototype parts

The Scheme G "-v3" top and bottom magnet holder prototype parts ordered 05Mar12 from Shapeways arrived back on 16Mar12. These parts seem to work well as long as the size of the laser-cut hole in the acrylic is well controlled.

The nominal dimensions of the parts (which is what you would use if you were designing injection molded parts) are slightly different than the actual dimensions of the 3D printed parts I specified to Shapeways. The following description of the process I used to design these parts will provide these nominal dimensions. The nominal dimensions are probably the dimensions that arakis should use for his images. A later posting will describe the adjustments I made to create the actual dimensions.

I used Autodesk Inventor Professional 2012, so most CAD tools will probably use a somewhat different procedure.
I used 1.5 mm acrylic, but the extension of the design to 2.55 mm acrylic and 3.0 mm acrylic is fairly straight forward.

The vertical dimension budget of my cases can be assumed to be
    1.5 mm ~ top cap
    1.5 mm ~ top acrylic
    5.0 mm ~ space-above-board
    1.7 mm ~ board
    1.8 mm ~ space-below-board
    1.5 mm ~ bottom acrylic
    1.5 mm ~ bottom foot
    ----------
    14.5 mm ~ overall



Scheme G Bottom Magnet Holder
    Start Autodesk Inventor Professional 2012...
    New > Metric > Standard (mm).ipt
    ----------
  • Magnet Boss
    Create 2D sketch on "XY" plane > 5.000 mm circle @ origin... [b1]
    Extrude 3.400 mm in +Z direction... [b2]
    Set Feature Color Style Property to "Red (Flat)" for now...
  • Foot
    Create 2D sketch on "XY" plane > 8.000 mm circle @ origin... [b3]
    Extrude 1.500 mm in -Z direction... [b4]
    Set Feature Color Style Property to "Orange" for now...
  • Foot Indent
    Create 2D sketch on bottom of foot > 5.000 mm circle aligned with foot... [b5]
    Cut 0.500 mm in +Z direction... [b6]
    Set Feature Color Style Property to "Green (Flat)" for now...
  • Fillet
    Fillet > 0.500 mm radius > outside edge of foot bottom & inside edge of foot indent... [b7]
    Set Feature Color Style Property to "Blue (Flat)" for now...
  • Magnet Well
    Create 2D sketch on top of magnet boss > 3.000 mm circle aligned with magnet boss... [b8]
    Cut 2.300 mm in -Z direction... [b9]
    Set Feature Color Style Property to "Cyan" for now...
  • One-way Barb
    Create 2D sketch on "XZ" plane > 0.800 mm tall by 0.300 mm wide triangle which is 1.600 mm away from foot... [b10] [b11] [b12]
    Sweep this triangle around the magnet boss using the top of the magnet boss as the "path"...
    Set Feature Color Style Property to "Yellow (Flat)" for now...
    ----------
    Save as > SoB-case-SchemeG-bottom-barb-18high-15thick-dsm-v4.ipt
Notes
    [b1] 5.0 mm == 3.0 mm diameter neodymium magnet + 1.0 mm thick magnet boss wall + 1.0 mm thick magnet boss wall
    [b2] 3.4 mm == 1.5 mm acrylic + 0.1 mm margin + 1.8 mm space-below-board
    [b3] 8.0 mm ~ looks
    [b4] 1.5 mm ~ looks
    [b5] 5.0 mm ~ looks
    [b6] 0.5 mm ~ looks
    [b7] 0.5 mm radius ~ looks
    [b8] 3.0 mm == 3.0 mm diameter neodymium magnet
    [b9] 2.3 mm == 3.0 mm long neodymium magnet - ((board - 0.3 mm) / 2)
    [b10] 0.8 mm ~ looks
    [b11] 0.3 mm == ((5.2 mm hole in acrylic - 5.0 mm magnet boss) + 0.4 mm) / 2
    [b12] 1.6 mm == 1.5 mm acrylic + 0.1 mm margin
SoB-case-SchemeG-bottom-barb-18high-15thick-dsm-v4-top-orthographic.jpg
SoB-case-Scheme-G-bottom-magnet-holder-dsm-v4 ~ top view
1.8 mm space-below-board ~ 1.5 mm acrylic ~ color coded

SoB-case-SchemeG-bottom-barb-18high-15thick-dsm-v4-bottom-orthographic.jpg
SoB-case-Scheme-G-bottom-magnet-holder-dsm-v4 ~ bottom view
1.8 mm space-below-board ~ 1.5 mm acrylic ~ color coded

SoB-case-SchemeG-bottom-barb-18high-15thick-dsm-v4.zip
SoB-case-Scheme-G-bottom-magnet-holder-dsm-v4 ~ STL file
(242.18 KiB) Downloaded 202 times



Scheme G Top Magnet Holder
    Start Autodesk Inventor Professional 2012...
    New > Metric > Standard (mm).ipt
    ----------
  • Magnet Boss
    Create 2D sketch on "XY" plane > 5.000 mm circle @ origin... [t1]
    Extrude 6.600 mm in -Z direction... [t2]
    Set Feature Color Style Property to "Red (Flat)" for now...
  • Top Cap
    Create 2D sketch on "XY" plane > 6.000 mm circle @ origin... [t3]
    Extrude 1.500 mm in +Z direction... [t4]
    Set Feature Color Style Property to "Orange" for now...
  • Fillet
    Fillet > 0.500 mm radius > outside edge of top cap... [t5]
    Set Feature Color Style Property to "Blue (Flat)" for now...
  • Magnet Well
    Create 2D sketch on bottom of magnet boss > 3.000 mm circle aligned with magnet boss... [t6]
    Cut 2.300 mm in +Z direction... [t7]
    Set Feature Color Style Property to "Cyan" for now...
  • One-way Barb
    Create 2D sketch on "XZ" plane > 0.800 mm tall by 0.300 mm wide triangle which is 1.600 mm away from top cap... [t8] [t9] [t10]
    Sweep this triangle around the magnet boss using the top of the magnet boss as the "path"...
    Set Feature Color Style Property to "Yellow (Flat)" for now...
    ----------
    Save as > SoB-case-SchemeG-top-barb-50high-15thick-dsm-v4.ipt
Notes
    [t1] 5.0 mm == 3.0 mm diameter neodymium magnet + 1.0 mm thick magnet boss wall + 1.0 mm thick magnet boss wall
    [t2] 6.6 mm == 1.5 mm acrylic + 0.1 mm margin + 5.0 mm space-below-board
    [t3] 6.0 mm ~ looks
    [t4] 1.5 mm ~ looks
    [t5] 0.5 mm radius ~ looks
    [t6] 3.0 mm == 3.0 mm diameter neodymium magnet
    [t7] 2.3 mm == 3.0 mm long neodymium magnet - ((board - 0.3 mm) / 2)
    [t8] 0.8 mm ~ looks
    [t9] 0.3 mm == ((5.2 mm hole in acrylic - 5.0 mm magnet boss) + 0.4 mm) / 2
    [t10] 1.6 mm == 1.5 mm acrylic + 0.1 mm margin
SoB-case-SchemeG-top-barb-50high-15thick-dsm-v4-top-orthographic.jpg
SoB-case-Scheme-G-top-magnet-holder-dsm-v4 ~ top view
5.0 mm space-above-board ~ 1.5 mm acrylic ~ color coded

SoB-case-SchemeG-top-barb-50high-15thick-dsm-v4-bottom-orthographic.jpg
SoB-case-Scheme-G-top-magnet-holder-dsm-v4 ~ bottom view
5.0 mm space-above-board ~ 1.5 mm acrylic ~ color coded

SoB-case-SchemeG-top-barb-50high-15thick-dsm-v4.zip
SoB-case-Scheme-G-top-magnet-holder-dsm-v4 ~ STL file
(142.16 KiB) Downloaded 182 times

Thanks for your time.

dsm
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Re: Standoff size and side height

Postby dsm » Fri Mar 23, 2012 1:35 pm

Scheme G actual dimensions

dsm wrote:The nominal dimensions of the parts (which is what you would use if you were designing injection molded parts) are slightly different than the actual dimensions of the 3D printed parts I specified to Shapeways.

Compared to the nominal dimensions of the parts, the actual dimensions of the 3D printed parts I specified to Shapeways differ in the following respects:
  • The magnet boss diameter is slightly too small, so the actual dimension should be increased from 5.0 mm to 5.05 mm.
  • The magnet well diameter is slightly too small, so the actual dimension should be increased from 3.0 mm to 3.05 mm.
  • The retention barb height is slightly too small, so the actual dimension should be increased from 0.3 mm to 0.4 mm.
    0.4 mm may seem to be too large, but the dimensions of the retention barb ring are toward the lower end of the resolvable features for SLS parts and the sharp barb becomes a gentle "bump" around the outside of the magnet boss.
miscellaneous comments
  • The previous discussion assumes 1.5 mm acrylic with 5.2 mm holes to capture the Scheme G magnet holders.
  • The easiest way to make sure that the 5.2 mm holes are actually 5.2 mm is to laser-cut the holes slightly small and drill them out. 5.2 mm drills are available from McMaster-Carr (item #3056A274).
  • Acrylic can be slightly brittle, especially in the thinner material I prefer, so the edges of the holes in the acrylic should be supported with a backing plate (i.e. block of wood with a hole) when pressing the magnet holders into the acrylic.
  • Fumes from cyanoacrylate (e.g. super glue) are attracted to the organic material in fingerprints on the acrylic windows. Clean the acrylic windows carefully with isopropyl alcohol if you use cyanoacrylate glue.
Thanks for your time.

dsm
Last edited by dsm on Fri Mar 30, 2012 6:22 pm, edited 1 time in total.
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Re: Standoff size and side height

Postby dsm » Fri Mar 23, 2012 2:33 pm

Scheme G injection molding

Given the adjustments needed to fabricate Scheme G parts in SLS nylon via Shapeways (see previous postings), I've given some thought about how to injection mold these parts. Since I started out from a 3D printing perspective, these parts can be quite complicated [1] from an injection molding perspective. I considered two approaches...
  • Eliminate the one-way barb. This allows a simple top and bottom mold scheme. The dimensions of the magnet boss and the magnet holder holes in the acrylic would have to be controlled very carefully and/or glue would have to be used.
  • Use a more complicated mold with top and bottom molds with side pulls. To allow the same top and bottom molds to be used for different thicknesses of acrylic, change the thickness of the side pulls between the bottom foot (or top cap) and the one-way barb. Note that the parting line for the side pulls is covered by the acrylic holes.
SoB-case-SchemeG-top-barb-50high-15thick-dsm-v4-molding-side-view.jpg
Scheme G top magnet holder
top cap in red, side pull area in green, bottom in orange

SoB-case-SchemeG-bottom-barb-18high-15thick-dsm-v4-molding-side-view.jpg
Scheme G bottom magnet holder
top in orange, side pull area in green, bottom foot in red

Thanks for your time.

dsm

[1] For example parts of similar complexity, visit the Richco site (link).
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Re: Standoff size and side height

Postby dsm » Fri Mar 23, 2012 3:25 pm

Design 2 Part show

I attended a regional Design 2 Part (link) job shop show yesterday to investigate vendors for getting some metal parts fabricated.

While I was there, I spoke to injection molding vendors about getting the Scheme G top and bottom magnet holders fabricated.
I brought along some assembled sample Scheme G cases and a dimensioned CAD drawing (see below) to leave for quotations.
Experts suggested several relatively inexpensive ways to get these parts fabricated.
Questions that all the vendors asked included the following:
    What material?
    What volume?
    In what format is the CAD data?
As to material, Richco (link) uses injection molded nylon (link) for similar parts, although one vender suggested urethane.
As to volume, I had no ready answer. Since I haven't heard back from either ian or tayken about the samples I sent,
I have no feedback on whether the whole Scheme G approach should be considered viable. Oh well...

I ended up handing out seven copies of the attached document to request injection molding quotes for Scheme G parts
at the 1k, 5k, and 10k volume level in a polyamide polymer (e.g. nylon).

SoB-case-SchemeG-top-bottom-15thick-dsm-v4.pdf
SoB-case-SchemeG-dsm-v4 ~ top and bottom dimensioned CAD drawing
(114.03 KiB) Downloaded 300 times

Thanks for your time.

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Re: Standoff size and side height

Postby ian » Tue Mar 27, 2012 9:59 am

My first test of the acrylic cuts based on Filip's files.

Picture of all the samples dsm sent :) Thanks again.
Attachments
dsm-trials.jpg
bp-v3.5e.jpg
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Re: Standoff size and side height

Postby tayken » Wed Mar 28, 2012 10:46 am

I remembered that I didn't write something yet. But here we go:

Scheme G: I really liked them. But for injection molding we have to be sure that they can be molded in a good way. We will have to work with an engineer and front end cost (aka cost of mold) is a lot, probably we'll have to redo the mold after a couple of years. Also we have to check out the pricing too. "How much is the total cost including the top pieces, bottom pieces and magnets?" is an important one. Also magnets should be glued. But this can be left to the final user.

Custom spacers: Also like Ian I didn't pull them out as it looks really good that way. :) But something like this can be cost effective if we can find sizes that we like from a supplier in China. One approach can be getting an extruded plastic tube with the required diameters and then cutting it to size by the laser cutter. Multiple tubes can be cut in one go.

Side walls: The case with side walls looked good, was easy to assemble (meaning you don't have to press really tight) but there was too much play between the pieces that it does not feel solid. It also made assembly a little harder as you have to manipulate the side pieces to fit the slots. However, this can be avoided by playing with dimensions to have some type of friction between slots and tabs. Also some sort of interlocking (probably the second type presented in my Sketchup code) will be helpful during the assembly as pieces can rest onto each other.

Acrylic thickness: We have to see what thickness is available but testing some pieces of acrylic proved that 1.5 mm is too thick. With the cases, I'm able to squeeze the case with minimal force whereas the 3 mm case I laser cut does not show any bending but it can be too thick and costly. 2.55 mm can be a good middle ground if Seeed can source enough. My guess is any thinkness between 2 mm to 3 mm will be solid enough to put that case into your bag and run around with it without worrying about whether the case can take the abuse.

Durability & Accessibility: This is directly related to acrylic thickness and mounting. Thicker acrylic with nuts&bolts are good for a solid case that you can put into your bag while going to school or hackerspace or coffee shop. But it requires some work to open up the case to connect, say, a programmer. Thinner case with magnets can easily come undone inside a bag, acrylic can get broken etc. But it is easier to open the case. I guess this is an important question that we have to answer so that we can decide on mounting option (spacers&nuts&bolts or magnets with custom plastic parts) and also acrylic thickness. Another thing to look is the cost.

One thing that we can do is have both options out there saying "We advise this case for tougher situations" and "We advise this case to be used on a bench, not bag-filled-with-books resistant!"
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Re: Standoff size and side height

Postby dsm » Fri Mar 30, 2012 6:50 pm

Scheme G v4 update - part I

Attached is an updated dimensioned CAD drawing of the Scheme G v4 top and bottom magnet holder variants to support the following acrylic thicknesses...
    1.5 mm
    2.55 mm
    3.0 mm
SoB-case-SchemeG-three-variants-dsm-v4-injection-molding-highlight.pdf
SoB-case-SchemeG-dsm-v4 ~ dimensioned CAD drawing ~ three variants
(137.48 KiB) Downloaded 247 times

dsm wrote:The nominal dimensions of the parts (which is what you would use if you were designing injection molded parts) are slightly different than the actual dimensions of the 3D printed parts I specified to Shapeways.

The CAD drawing drawing documents what I believe the dimensions should be for injection molded Scheme G parts.
The dimensions highlighted in yellow should be modified as described in a previous posting (link) if the parts are to be
3D printed in SLS nylon by Shapeways.

If you have any suggestions about a better way to communicate this design data, please don't hesitate to speak up.

Thanks for your time.

dsm
Last edited by dsm on Sat Mar 31, 2012 12:37 am, edited 1 time in total.
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