MetaWearC case: first concept

Gadget

Hi there,

As long as I'm waiting for my MetaWearC boards to arrive, I started to design a case for it. 

I was wondering, what you guys think about it...

http://www.thingiverse.com/thing:1176990

CHeers 

Gadget

Laura

Gadget,

This is awesome! I will post it in our next newsletter!

Gadget

Thx Still working on it. Any news regarding shipping?

Matt

@Gadget

Had a chance to print your case out last night.  It printed out with really good quality.  Did not have any issues slicing with Simplify3D or printing on a FlashForge Creator Pro.

The latching mechanism printed pretty well for having a slight overhang, and I think it will work perfectly:

The lid pieces ended up being a little tight to fit the base for me.  With calipers my inner diameter on the base was around 23.9mm, and the outer diameter of the lid part that interlocks was 4.2mm.  The outlines might print slightly thick on my printer.

At 23.9mm the base was a little to tight to fit the engineering sample I have in it.

The lever arm for the built in switch version of the lid ended up welding shut in my print.  I should note that I print ABS on glass with ABS juice -- so I REALLY squish the first layer to get it to stick.  It resulted in the outlines overlapping on the first 1-2 layers.

On one of the test fixtures I've been working on for MetaWearC, the device fits extremely well with a 24.5mm drawn inner diameter.  Again, my printer seems to print slightly thicker walls, because the printed inner diameter ended up at 24.2mm.  The alignment ribs worked well for me at 0.8mm width, 0.8mm depth.

There will be an update soon on Kickstarter.

Gadget

wow thank you for the detailed report!
I will rework the locking mechanism and diameters for a better fit.
Do you print with a 0.4mm nozle?
It's hard to get the dimensions right, but I guess I'm on the right track

Gadget

Dear Matt

Just to put it all together:

Base:

- Inner diameter slightly to tight

- walls could be thicker

- Could you post a picture with the metawear inside the base?

Lid (simple):

- Fit too tight 

- Does the lid latch to the base?

Lid (button):

- I wanted the lid to be tight. Might be a bit too much ^^

- Need to add closing mechanism.

Gadget

@Matt: Updated the design. Check it out

Matt

@Gadget

I'm printing with a 0.4mm nozzle.

The summary captured everything pretty well.  The walls seem thick enough to me though.

I was unable to test the latch mechanism because the diameter tolerance would not allow the two pieces to interlock.  Same goes for the MetaWearC board inside the base.

I'll print out the revised pieces and report back!

Matt

@Gadget

The new lid fits the case very well, and the twisting latch mechanism works well.  I would say the fit on the lid is ever so slightly tight.  It would definitely stay put just with friction, and it had to be very slightly forced to fit together -- though not enough to damage anything so it could be considered good.

The inner diameter on the base is still slightly tight to fit the MetaWearC.  I was able to put the board in the base, but not get it completely inserted to the bottom.  Removing the board took some effort as a result.

Looking at the size, I think the lid should fit with no problem with the board inside, but without being able to completely insert the board I can not definitively confirm.

Great work!

Gadget

Finally got my filament restocked. I think I will drop the twist mechanism, as with such small dimensions, 

it would be too weak. Going to design a "snap-on" cap i think.

Gadget

@Matt I will adjust the diameter this weekend and rework the closing mechanism (hopefully) ^^ are the notches ok or do they need to be a bit smaller?

Gadget

@Matt: To make the dimensions matching a bit more efficient, could you check out the following two files and see what version fits best?

Notches: https://www.dropbox.com/s/rtihewqf2pf2tv1/01_test_notches.stl?dl=0

Diameter: https://www.dropbox.com/s/yvj0ejp9j0zogrm/02_test_dia.stl?dl=0

Gadget

http://www.thingiverse.com/thing:1194632

Laura

@Gadget, This is freaking awesome, we will have to wait to print after the holidays though!

Matt

@Gadget: I got both test files printed off.  From what I can empirically tell, the smaller features start from the left of the models.

With both tests, the second from the left has the best fit.

In the diameter test, the left most is too tight to pass the MetaWear.  The second must be aligned well, but passes without pushing or forcing.  The next two options are progressively looser.  The second diameter measures 24.2mm with calipers, identical to the printed diameter used in the MWC test fixture.

In the notch test, the left most has quite a bit of wiggle but could be considered good.  The second to the left has a small amount of wiggle.  The third appears to fit, with no wiggle at all.  I recommend the second option as once a model is equipped with four there should be very little remaining play.

The thingiverse link was not working for me when I printed the test models but is working now.  A water proof case!? That is awesome.  I'll be printing it out when I get in tomorrow.

Cheers

Gadget

@Laura: Thank you very much! Can't wait for my MWCs (ordered six of them ^^ )

@Matt: If you are planning on printing tomorrow, I will adjust the dimensions shortly. Hopefully it will result in a perfect fit My test-print had also 24.2 so we should be good. Current versions already have the correct diameter, but the notches are still a bit bigger. 

Sadly I don't have a o-ring to check the waterproof case. But hey, it's a start ^^

Matt

@Gadget: If you want to update the files, I will wait to print the new version.

I'll take a look to see if I can find a source for the o-rings convenient enough for most users -- Amazon over McMaster or similar.  Otherwise maybe we can place a bulk order on our end and offer them to interested users with their store purchases.  We have relatively easy access to a laser cutter, so maybe we could provide clear acrylic top windows as well.

Awesome project Gadget!

Matt

@Gadget: Here are some o-rings that might be good fits.  It looks like McMaster doesn't stock a 27mm diameter, 1mm wide o-ring.  The 26mm or 27mm diameter, 1.5mm wide might work well though.

http://www.mcmaster.com/#o-rings/=9p6q8gvpduii6ee8l1

Gadget

@Matt: I updated the waterproof case
the regular one is still not finished. I printed out a version of it and I'm not yet happy with the result ;-)
I can adjust the waterproof case, to fit a 1.5mm o-ring. Acrylic top would be awesome, especially if you want to use the pro version with the ambient light sensor!

Matt

@Gadget : Version 2 of the waterproof case prints out very nicely.  I had to force the MetaWearC slightly, but it fit.  Seems like a 1.5mm o-ring is much easier to source. 

 Acrylic top would be great, I'll try cutting one if you could export a DXF of the top view.  Or maybe I could get that out of the STL -- I've never tried.

Gadget

@Matt: as soon as I find the time, I will post the dwg. additionally I want to add a notch inside, to allow easier removal of the MWC => no shaking and wiggeling required.
Regarding the dimensions: Can I keep the current diameter or should I tweak it a bit more?

Btw: Any chance, to get the MWC Pro instead of the regular one? Backed the projekt with the family pack and would gladly pay a bit extra ^^

Cheers

Gadget

Gadget

@Matt: Exported the lid as DXF. Could you check, if it works for you? If yes, I would post it on thingiverse.

https://www.dropbox.com/s/j8acazijd947pkq/02_top_fix_V1_flat.dxf?dl=0

Matt

@Gadget: Regarding the diameter, I would increase it by 0.15-0.25mm.  It fits but it is tight and difficult to remove.

Regarding the DXF file, the perspective is challenging for me to do much with.  I have not been able to get a clean top perspective of the object, though that may be my inexperience with the CAD tools.  Could you try exporting with the view looking directly into what will be the glass window?  That should produce a 2D drawing with the outline of the window and lines for the screw holes that would be ready for laser cutting.

Gadget

@Matt: Sorry, my bad. Did not select the proper view during export ^^

Does this one work better: https://www.dropbox.com/s/vn1e7wljofy2fsw/02_top_fix_V1_flat.dxf?dl=0

Gadget

Reworked the design for the simple enclosure and posted it on thingiverse:

Matt

@Gadget: The DXF file looks good, and the dimensions inferred by the cutter software seem be to right.  I will have a chance to use a cutter later this week and make a few pieces to test the size.

The simple enclosure looks awesome, I'll print one off tomorrow.

Cheers

Matt

@Gadget: The new simple enclosure looks great!

I had a chance to cut the lid piece on the laser, but only had access to a blue acrylic sheet.

The dimensions ended up being slightly off but I have not yet figured out why.  The four corners with holes and the holes are slightly wider than the 3d printed piece.  The four "bulges" however align with the case perfectly.  I'm fairly certain I printed version two of the base piece -- the lid I have is the one with the round extrusion in the center for alignment.

With calipers I measured:

40.75mm : Acrylic corner to corner

38.75mm : 3D printed base corner to corner

41mm : DXF file corner to corner in CAM software

I'm lead to believe that my 3D printer must print a bit narrow in the X-Y, which would explain the tight fit of the MetaWearC as well as this dimension mismatch.  The bulges matching do not agree though.

What corner to corner distance do you have in your mechanical CAD tools?

Tinker

Thank you for putting these up.  On your waterproof case, How did you initialize the Metawear C on/off if you could not get to the button?

Eric

The button is not an on/off switch; the board is always on when it is supplied power.