deskthority

Rodent MK II
Edit: It is a mouse, which I realized I never actually mentioned anywhere below in case it isn't obvious.

I have decided to make an improvement of an old project I made. There were some issues which I have always intended to correct, and with some neat avago sensors available now I might get some help making the internals as well. I will try to piggy back a bit onThe_Ed's project and just use his internals, saving me a bunch of work in a field I ain't very good at. Last time I butchered a G300, but the ability to control the software, liftoff distance, angle snapping, acceleration and such intrigues me.

Process so far: (crash course)
Create a clay model (actually just dough, nothing fancy here) which fits your taste.
Melt vinyl record on top to create a shell > Didn't turn out that great, although it would probably eventually have worked decently but required a lot of effort to get there. Internal structure is a pain with that method.
Remake another clay model because the old one got ruined by previous attempts.
Make a 3D scan of the clay model.
Retopology, adjust shape, add and correct some features etc.
Add structural elements.
Print the computer model.
Butcher an old mouse for internal parts and transplant them into my mouse.
Live with the flaws because you don't bother fixing them, for instance non working scroll wheel.

Thus begins the process of creating a better one, starting out with one of the scans again. Mesh



Things left to do:
-CHECK-Better mounting for the bottom plate, a step would probably be sufficient, and hide the plate nicely. 3mm bottom plate?
-CHECK-Use hexagonal slots where nuts fit. This will yield far more durable threads.
-Better mounting for the Omron switches than last time, allow them to be securely fastened while easier replaced (Note to self: remember to use longer cables this time to make assembly easier)
-Move some mouse buttons a bit.
-Fix the scroll wheel which was sort of bugged and never really worked well. This is probably the most annoying and hardest part atm.
-CHECK-Plan better locations for the feet. Should they be on the bottom surface of the shell or on the plate? located on the plate would ensure strength and stability, but that can be accomplished by increased shell thickness at the bottom as well. It is preferable to place them as far out towards the edges as possible. The more bottom surface belonging to the shell, the smaller the hole to assemble/repair though
-Smooth out a few dents still present from the clay model. They can be sanded down but might as well fix it now.
-The software/teensy/avago stuff which I hope I won't have to do that much of.
-Make a better name, Rodent was just a prototype name.

I made a far better inner surface this time. The shell is of even thickness on pretty much the entire surface except for at the bottom where it is thicker to meet up with the slot for the bottom plate better. It is also thicker, 2mm now, to account for weaker material. Supports will be added to certain points for structural rigidity as well though. I want to keep the amount of material, cost and weight down. It is somewhat hard to show with a complex organic surface though. I made it a bit like an x-ray where you can see the inner surface through the opaque shell.

http://i.imgur.com/AZHNthv.png
http://i.imgur.com/Z7Kpz8L.png
http://i.imgur.com/NAJJTAl.png
http://i.imgur.com/WQuD4HN.png

Perhaps this shows it better:
http://i.imgur.com/vuhAicm.png

Currently looking into scroll and micro switches. I intend to try a few. I have TIAIHUA and Omron and searching for a few by Cherry.

Cool! How do you intend to do the buttons? Cut slits into the body and let the plastic bend each time you press a button, or print individual buttons that fit and slide at the top of the mouse?

Good question. And already an intriguing looking mouse. Quite like the name, actually. I assumed "Mark I" referred to traditional mouse designs, and that this is the next big leap!

Findecanor wrote:Cool! How do you intend to do the buttons? Cut slits into the body and let the plastic bend each time you press a button, or print individual buttons that fit and slide at the top of the mouse?

Combination I guess, mostly because I am undecided. I have added places where I can place nuts to avoid threads in the plastic. For instance the forward/back thumb buttons can be either printed along with the bending part and screwed there, or put on a small piece of sheet metal and then screwed there. The sheet metal idea is probably best longevity wise.

I am currently doing the left and right mouse button. I always intended for them to just be part of the shell, and a simple slit in a U shape would be sufficient. The problem is that they are really convex, which will make them far stronger than I want them to. I decreased their thickness to 1 mm and they will probably still be too strong. I can always cut them out completely like and have a small piece underneath them which attaches to the shell and bends, but then it would bend on a very small area which is likely to cause problems. I don't think I have space for more nut placement sites as well.

The middle mouse button next to the scroll is so complicated that It has to be printed atm. It is also mounted with screws to some slots where I can secure nuts. The mounting for the switch which belongs to it takes up place, and both sides are occupied by the RMB and LBM and the actual scroll wheel and its rig takes up a lot of space. I am short of space in certain areas.

I am thinking of redoing the nut placement
This is how they look now. You slide the nut into the slot and it won't be able to rotate. i might fixate it with a small touch of adhesive. Not much though. I don't want it getting into the threads. Another pic of the inside of the shell

I could save a lot of space by doing this instead. The nut would just be placed in the slot with a little bit of adhesive. The hole behind it is required to allow the screw to pass through it a bit. Even with it, I am limited in the length of screws, or will have to use washers so that they don't stick in too far. It would be far weaker as well since the nut isn't behind anything. The only thing holding the nut in place would be adhesive. This is why I was against the idea at the start. However, if done correctly, the bending element screwed there will be screwed against the surface of the nut and not the surrounding surfaces, hence I can screw really hard without it popping out. The adhesive would not have to resist such a large force as when you could have caused if the benind element would touch the surrounding surface first. The adhesive will just have to resist the forces applied when the button is pressed which is far less. A bit complicated in text, but hopefully it is understandable.

Muirium wrote:Good question. And already an intriguing looking mouse. Quite like the name, actually. I assumed "Mark I" referred to traditional mouse designs, and that this is the next big leap!

I actually did one before, hence Mark II. It was sloppy in comparison though. This aims to correct a bunch of issues it had.

damorgue wrote: The problem is that they are really convex, which will make them far stronger than I want them to. I decreased their thickness to 1 mm and they will probably still be too strong. I can always cut them out completely like and have a small piece underneath them which attaches to the shell and bends, but then it would bend on a very small area which is likely to cause problems.

Perhaps you could print the hinges as solid parts that sort of hook together. A button could have a horizontal rod that fits inside hooks inside the shell, or vice versa. It wouldn't have to be a snap fit. Then when you have screwed on the bottom plate, an edge on the bottom plate would prevent the buttons from sliding forwards.

damorgue wrote: I am thinking of redoing the nut placement
This is how they look now.

Why have three nuts side by side?

Why would it be so bad to thread in plastic? Make the plastic solid and thick, drill a hole and tap it.

If I had a longer nut, something like a regular standoff perhaps, it would allow me to use the space behind the nut. That space would otherwise have been wasted as a hole for the screw to have a bit of clearance. Instead, I get a few extra threads, and more surface to put adhesive on. I might go for a female-female standoff instead.

Findecanor wrote:

damorgue wrote: The problem is that they are really convex, which will make them far stronger than I want them to. I decreased their thickness to 1 mm and they will probably still be too strong. I can always cut them out completely like and have a small piece underneath them which attaches to the shell and bends, but then it would bend on a very small area which is likely to cause problems.

Perhaps you could print the hinges as solid parts that sort of hook together. A button could have a horizontal rod that fits inside hooks inside the shell, or vice versa. It wouldn't have to be a snap fit. Then when you have screwed on the bottom plate, an edge on the bottom plate would prevent the buttons from sliding forwards.

Not sure I get what you mean there. Could you make a picture?

Findecanor wrote:

damorgue wrote: I am thinking of redoing the nut placement
This is how they look now.

Why have three nuts side by side?

I haven't posted everything here on DT, sorry about that. This should explain Why I have used 3 nuts in certain places:

damorgue wrote: The easiest way to adjust the strength of the switches would probably be something like this:


The upper block is attached to the mouse and the lower is screwed to it. The bump at the far end would be where the button protrudes through a hole in the shell.

This would allow me to select where to fixate the button and a shorter distance from point of attachment to the button of course means a stiffer button and vice versa.

I could have the button be attached directly to the shell and built in one piece, but this also allows me to change the buttons in the future if they break. I can also put a small strip of sheet metal there to act as the deforming part if I feel like it and only have a button at the the end of it.

Currently estimating the forces and elastic deformation of ABS to get a rough idea of what length and thickness I need without it breaking.

Findecanor wrote: Why would it be so bad to thread in plastic? Make the plastic solid and thick, drill a hole and tap it.

I have bad experiences with threads in plastic. Often, they just use a self-tapping screw even.

I also have some possibility to adjust the strength of the buttons by selecting certain micro switches, but I would rather have a strong switch and a weak hinge as this would make the tactile feedback from the switch stronger.

Anyone know of a good source of eutectic solder in EU? I am running out and am unable to find any for a reasonable price. Most stores appear to have decreased or completely removed theirs election of solders with led. I don't have to comply to ROHS, just looking for some plain 63/37. With "EU", I just meant reasonably cheap to ship to Sweden. EU also means less hassle with customs fees. I have asked around regarding this but perhaps you guys know?

You can easily get 60/40 from conrad.de or reichelt.de, but 63/37 has become very rare here.

Conrad also has an expensive 62-36-2AG solder ive heard good thing about.

vun was able to find two places who sold eutectic solder in Norway, but they were some brands I haven't heard of before, they did not include VAT and finally came to a price similar to Kester 44+shipping from US. Why did everyone stop selling 63/37? Is there a reason I have missed why 60/40 is still around and preferable?

Only thing I could find was this: http://www.ersa-shop.com/sn63pb37-bleih ... -2274.html
But I guess you need wire... Did you try and contact them to ask why they don't have it as wire?

Yes, you are correct. I did not specify it but I would like it in wire-form with rosin core(s) within. Something like 0.4-0-7mm diameter with the ideal probably in the middle. That site seems to be in foreignese, aka German. If they don't have it listed they probably don't carry it. I found a site listed on the Kester distributors page. They don't seem to sell to private people but I have asked them anyway.

Why is this so hard? Why does all 63/37 seem to be gone, did I miss something where everyone found out that 60/40 was better for some reason? If this fails I will give in and just get 60/40. I just don't understand why.

Less has happened with this lately because of distractions. It is finished now, just playing with it so I should get back to this soon.

I have ordered some more parts, for instance sockets, connectors and cables for the switches to attach to, and which will collect them all into one cable which will attach to the controller.