Improving and powering the mount
Friday, November 6, 2020The plan
The mount I have now is pretty rudimentary, and I think I can do better. I'm going to design a new one that'll be better in that it'll:
Be more compact. The pillars holding the phone are thicker than they need to be, and so it the footing. I should be able to slim it down quite a bit.
Look nicer. I'll attempt to filet it to give it rounded corners a sleeker look.
Be higher. The field of view of the current holder is okay, but an 10mm would improve the sight lines slightly
Be closer. I'll try to give the base a curve that somewhat matches the curve of the steering wheel shroud so that I can fasten the mount slightly closer to the driver.
Be powered. That's right, I'm going to add a wireless charger to it so that my phone recharges while "being" an instrument cluster! And no wimpy USB port either, I'm going to hardwire into a 12v source.
Charger
To integrate a charger, I want to find something that's as thin as possible so that the mount doesn't grow back to the girth of v1, and ideally something that's a single piece and easy to design mounting for.
This seems to fit the bill, at only 3mm thick, and a nice compact round shape I can easily create a pocket for.
CAD design
I'm not an expert CAD user, and it shows every time I sit down and try to design a part. I don't know how to use the fancier tools, and I almost always design in a way that makes it impossible to go back and adjust things in early steps. Basically, I start with box and extrude and cut from that in a directions! It gets the job done, but it's tedious and sloppy, and I want to improve my skill, not just produce a part. So I'm going to try to design with more extensive sketching, and avoid building the part piecemeal.
So, in that spirit, I ditch the old CAD file and started new with a complete sketch of the mount.
So very similar to the previous design, except for the top, because I'll build a pocket for the charger. Padding this gives me the basic structure I'm going to work with.
Pad out the base, pocket the phone area, and sweep the holder groove and I'm basically at v1.
Now, I need to pocket the back of the holder to align the center of the charger with the center of the phone when held. Additionally, I need to have a tunnel to get the cable up there. I'm thinking the cable should exit through the back of the footing. Going straight down would allow me to hide the wire completely, but also require drilling the shroud, something I don't want to do yet. I don't think it'll be visible from many angles anyway - certainly not from the driving position.
The semi-circular groove is to accept the back lid that'll cover the electronics. I designed all of to have 2x minimum wall depth (1.6mm). Hopefully this is strong enough. The cover needs to come out at the base to ensure the usb connector has the clearance it needs. Here's what I came up with.
Here my lack of knowledge of CAD really showed, as building the cylindrical notch seemed very tedious. Why can't I just slap a cylinder there, shell it, and tapper the end? What I actually ended up doing was a series of pad/pocket and some filets to round things out. Speaking of fillets, here's how the mount turned out fully dressed up.
So much time to dress up, but that's okay, as it's the satisfying part of the process. You get to play around with different ideas and see what looks best.
Comparison with v1
All goals were attained. I didn't manage to slim it all that much, but a little, and that's with adding a charger. The back will add a little depth, but it's not a lot and it's not the full width of the holder. All and all, pretty happy with how the design turned out. Now, will it work?
Printing
It's going to take soooo long to print these 2 parts. Both parts I'll print standing up (even the cover that's pretty narrow, I hope it holds), with 20 infill (although the cover is so thin that won't matter), and supports.
The cover printed okay, but there a ugly vertical striation lines - not sure what caused that. Looking at the lip though, I don't think it'll be deep enough to hold itself in place in the holder's rear groove. Oh well, I might just double-side tape it. Clearances look good. I intentionally didn't integrate any mounting posts because I didn't want to risk having to reprint this whole thing just because a post is off by a mm. I think it should wedge just fine, and if needed, yup, double side tape again! 😂
Starting on the 12 hour mount now. Ugh, my filament feeder stepper is skipping. The joys of 3d printing...
Assessing fitment
It's off the printer, and there are some issues. In the picture you can clearly see a horizontal line at the top of the holder. It's in fact a recess, which isn't in the model or the slice, so the plate stepper must have slipped. Not a fatal flaw, but... the phone doesn't fit this mount! It somehow isn't as wide as v1, even though both models measure 150mm side to side (from the inside of the groove). I guess I'll try to whittle it down and make it fit. I just measured the finished part, and it's less than 150mm - printer error I guess?
The charger fits well, but there's a problem with the usb cable: the plastic connector shroud doesn't clear the bend. I'm going to trim it and see it that clears.
I compared the v1 and v2 w/r to fitment, and they are the same. The reason why v1 works is that the pillars don't have a backing plate to rigidity, and flex a little to accommodate the phone! So it's engineer error, not printer error.
Assessing looks
That's function, what about the looks? Well, I'm happy with the size, and the dressing, which looks amazing! I'm not sure I like how the rounded back plate looks. I'm thinking it may look better by keeping the 4mm curves used by the filets elsewhere. Probably make it easier to mate up with the holder to. I also don't like how the side pillars stick out from the back plate. The idea was to leave that space so I could pull the phone out of the holder without resorting using my thumbs to pull up on the screen.
Finishing and testing
... didn't happen. As I was trying to whittle down the sides for phone clearance, I broke the top part as seen below. It's kind of a flaw in the design, even if the printer hadn't messed up. I also never got the damn thing to clear, and was down to the infill!
So, it's back to the CAD drawing board. Disappointing, but v3 will be even better!