Author Topic: DIY tablet computer, maybe.  (Read 4141 times)

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5417
  • Country: us
  • Republic of Vermont
    • www. sredmond.com
Re: DIY tablet computer, maybe.
« Reply #50 on: July 31, 2018, 10:51:21 AM »
I like it!  :thumbup: :clap:


Also, good to have on hand in case of a need for self defense. Remember Odd-Job and his hat?
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline vtsteam

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 5417
  • Country: us
  • Republic of Vermont
    • www. sredmond.com
Re: DIY tablet computer, maybe.
« Reply #51 on: July 31, 2018, 10:55:31 AM »
I'd probably have tried riveting over those standoffs. Just put a shoulder on one end, make it a little long, and tap artfully with a ball pein hammer.

If you want to get fancy, lightly countersink the sheet metal, then rivet over the stud, and finally file flat.
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #52 on: August 01, 2018, 08:47:42 PM »
I'd probably have tried riveting over those standoffs. Just put a shoulder on one end, make it a little long, and tap artfully with a ball pein hammer.

If you want to get fancy, lightly countersink the sheet metal, then rivet over the stud, and finally file flat.

I considered that back when I was planning on making it from aluminium. My concern was hitting the top with a hammer possibly warping it, but that's probably less of a concern after switching to steel and welding it.

That magic tape arrived today. I went for GPH-060GF since it was the cheapest I could find. It's one of the lower strength varieties I think.



It's been like this all day. I can see its real strength is the foam core preventing it from 'peeling', but it's still pretty impressive.

I've found that with adhesives the real test isn't how strong it is trying to rip it apart, but instead how well it holds over time. Maybe if I was smarter the datasheets might already tell me that.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #53 on: August 04, 2018, 03:55:42 PM »
Green paint from a spray can because it's what I have. It's not very good paint and runs easily.


I did a little test and the tape seems to hold to it. But not sure how it'll work in the long run but I can't imagine it'll be too bad. I'll bake it in the oven for a bit tomorrow to hopefully drive off all the solvent.

The handle area is crudely carved out with a forstner bit. I've got that router table and templates would've done a nicer job. But it's currently buried behind my main bench with stuff on it.


I didn't really think too far ahead with the handle in terms of how I was going to actually attach it. Probably just going to glue the bottom piece on with a single screw in the middle, and then the top part can also screw on. I'll drill some holes through the bottom part to reach the screws for the top panel. I don't think I did a very good job with it. I don't think I did a great job with any of this really! But i'm more concerned about the function.

Offline PekkaNF

  • Hero Member
  • *****
  • Posts: 2117
  • Country: fi
Re: DIY tablet computer, maybe.
« Reply #54 on: August 04, 2018, 05:23:16 PM »
I do many projects same way. I call first iteration POC (Proof of concept). I think my daugter inherited it from me: For a anime sword, she did first some drafts, then drew it 1:1, then we made very crude model from pine board (just to see if the length is fine, parts look about right size etc.) then she whitled some parts to see how thy would be on 3D, because many stuff is very different on comics pages. AND THEN we started working on plugs to make moulds, to make parts....

I'm very happy to leave details to "next model"....until I am happy with basics. I guess my design process is recursive  :scratch:

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #55 on: August 05, 2018, 10:51:11 PM »
I do many projects same way. I call first iteration POC (Proof of concept). I think my daugter inherited it from me: For a anime sword, she did first some drafts, then drew it 1:1, then we made very crude model from pine board (just to see if the length is fine, parts look about right size etc.) then she whitled some parts to see how thy would be on 3D, because many stuff is very different on comics pages. AND THEN we started working on plugs to make moulds, to make parts....

I'm very happy to leave details to "next model"....until I am happy with basics. I guess my design process is recursive  :scratch:

Yeah thinking about this, I think it's the way to go.

Tomorrow i'm just gonna stick that glass on, not bothering trying to blank the borders. My concern with vinyl is just how to get it evenly stuck down. I imagine a rectangle with thin borders would be a bit fiddly to get applied right. I also bought some of that glass paint but it's not very opaque, which I should've expected. A 'real' paint and sandblasting to get a better grip seems like the best way to go in that regard. But then the other problem is how to even line it all up with the active area of the display.

I'm probably also going to give the whole motherboard thing a miss since I'm not sure if it even works. And in reality it'd be more useful hooked up to my desktop. I'm just nervous about the thing dying at some point since it's getting pretty damned old at this point. I'd complain more about the lack of real progress in PC hardware over the last few years but really it's a great thing for not having to worry about biannual upgrades to still have a useful PC!

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #56 on: August 06, 2018, 07:02:43 PM »
And I did exactly that.



That gap along the top may be because the display isnt sitting fully flat against the glass. I was hesitant to put foam on top of the circuit board since I figure that might be delicate. And I need to fuss a bit with getting the right amount, as well as making sure there's actually room for the display cable. And I need to double check the glass is actually flat before I try forcing the display against it.



The handle has a coat of shellac on it. I've heard that shellac when stored dissolved for a while becomes uncurable. But i've yet to have that problem with this bottle I dissolved a couple years back.



The keys are from an old electronic calculator - if it ain't obvious! Kinda wish I put them a bit higher up on the upper cluster though. That microcontroller has been through the wars so i'll be surprised if it still functions.


Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #57 on: August 07, 2018, 06:14:30 PM »


Got the back plate cut. More of an odeal than I expected. The only thing actually attached is the display controller board in the lower left. I'm going to mount it with studs so I can adjust the height to hopefully clear the connectors over the top of the motherboard.

Little concerned about the inverter. I figure that'd be a source of interference if its too close to anything important. I'm also a little concerned about the insulation on that shrink tubing, even though I doubled it up. It'll probably end up sitting on top of the hard drive, maybe with a bit of grounded tin in between.

All I've gotta make now is a few bushings to raise the motherboard up a bit... and then the heatsink. I also wish I thought a little further ahead and drilled holes into the case for the exit vent and input/ output sockets, since i'll need to take it all apart again.


The heatsink... you can buy heat pipes and I guess solder them. They seem like they might be tricky to solder but i've got a gigantic burner. For the fins i'm considering cutting up a whole bunch of pop cans to make the vanes and just holding them together with a press fit on the heat pipe, since that's how they seem to construct alot of the real ones. Maybe I could make a little swaging die too to punch and stretch the holes.

Also gonna look on ebay for a 12 volt adapter. I was hoping i'd find one at the boot sales. Then I can actually test to see if the display works before really worrying about going further on the computer side.

Offline nrml

  • Full Member
  • ***
  • Posts: 207
  • Country: gb
Re: DIY tablet computer, maybe.
« Reply #58 on: August 08, 2018, 05:05:09 PM »
Nice work. This is certainly a very unique project. I've never seen anything quite like this and I mean that in a good way.

Judicious use of guitar shielding foil should sort out interference problems.
How about arctic silver thermal epoxy for building the heat sink. It wont be as efficient as a soldered joint but is likely to be far less of a hassle to put together.

Offline krv3000

  • Hero Member
  • *****
  • Posts: 2075
  • Country: gb
Re: DIY tablet computer, maybe.
« Reply #59 on: August 08, 2018, 05:28:33 PM »
in a word brill

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #60 on: August 08, 2018, 05:39:57 PM »
Nice work. This is certainly a very unique project. I've never seen anything quite like this and I mean that in a good way.

Judicious use of guitar shielding foil should sort out interference problems.
How about arctic silver thermal epoxy for building the heat sink. It wont be as efficient as a soldered joint but is likely to be far less of a hassle to put together.

That's not a bad idea at all. I've also seen heatsinks where the heat pipes are flat against the CPU with the plate holding them together on top, so maybe the loss in efficiency won't be a huge deal.

Wish I could tell if it was the CPU or motherboard that's at fault, if its even a fault at all. I'm considering putting that CPU inside my desktop since it'd be compatible but I kinda feel this computer is held together at this point by the dust caking the boards. I think Windows triggers the software protection if you switch CPUs out too but I only need to get as far as the POST.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #61 on: August 08, 2018, 06:22:31 PM »
I'm glad I did that even though it was terrifying. I thought i'd bent some pins on my CPU socket but i've got a foggy memory of thinking that when I first assembled the PC too - they just look weird.

So the CPU I bought is junk. Perhaps because it was sent in a paper bag but it might've been toast before that. I'll have to see if this place will accept it back without a fuss. What actually are my rights on this matter. I've never really pursued returning faulty items before but this one has me genuinely annoyed.

Thinking about bent motherboard pins. The first PC I ever tried to build I got sold a duff motherboard with a bent CPU socket pin. I was 13 or something at the time though so I couldn't really argue my point in returning it, and the guy insisted that I must've tried put the CPU in sideways or upside down or something. I got got.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #62 on: August 09, 2018, 04:57:04 PM »
12 volt AC adapter arrived today. I'm glad 12 volt adapters seem to be fairly standard in connector size.


I got so excited I forgot how to draw.

It's a TN display so the viewing angle isn't great.


You can also see where the top isn't entirely flat and the tape hasn't stuck. I managed to get some swarf into the gap too when drilling a dimple to clear a screw and it's now a permanent feature. Other problems are a fair bit of latency which could be from the controller board. I suspected something like that might happen.

And finally the cursor is... perfectly aligned. I think i'd like it offset a bit to the upper left of the pen nib to compensate for parallax and so the pen isn't actually obscuring it. The Wacom drivers are surprisingly sparse in features so i'd probably need to do that through the waxbee config thing for the microcontroller, which has some baffling options.

It's weird but i've gotten fairly used to my non display pen tablet and i'd consider not having your hand blocking the image a huge advantage. I actually find that a bit of a hassle when drawing on paper too, not that I do it alot.

Seems like alotta complaints. I'm really excited it works but there's still alot to fuss with to get it finished. I didn't ever expect it to replace my regular tablet though and so far it seems ideal for what I want it for - inking. Despite the screen latency the pen is very responsive with a good pressure ramp (or whatever you'd call it) and no jitter. Most of the wobbles in that doodle were from my hand sticking to the glass. You can actually buy cotton gloves for your ring and little finger to prevent that. They're often coupled with the commercial pen displays.

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 6417
  • Country: gb
  • East Sussex, UK
Re: DIY tablet computer, maybe.
« Reply #63 on: August 09, 2018, 05:08:20 PM »
 :thumbup: :thumbup: :thumbup:
Andrew Mawson
East Sussex

Offline krv3000

  • Hero Member
  • *****
  • Posts: 2075
  • Country: gb
Re: DIY tablet computer, maybe.
« Reply #64 on: August 09, 2018, 05:46:20 PM »
nice

Offline nrml

  • Full Member
  • ***
  • Posts: 207
  • Country: gb
Re: DIY tablet computer, maybe.
« Reply #65 on: August 10, 2018, 02:15:16 PM »
Very nice indeed :thumbup:.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #66 on: August 12, 2018, 09:29:43 AM »
Thanks for the comments!


I've been kinda delaying doing more on this as I try figure out what I even want to do with it. Plus I need to go get some coaxial DC connectors and the cars booked in the garage for tomorrow.

Gonna give the PC part a miss for sure. I think the display really isn't very good. It's fine for what I need it for, but even as a proof of concept I don't think it'd prove much since it's such old technology. As a regular pen enabled display theres not much going for it as theres fairly cheap IPS pen enabled displays from China out now. And for the computer side of it the motherboard I've got is a few generations old and of a format that seems to have been ditched by the manufacturers.

It seems like intels NUCs and equivalents really took off though and are still making gains. I've heard they're becoming popular in offices for their small size and low power consumption. Intel are also releasing the occasional gaming oriented NUCs with hefty price tags and heftier power consumptions but i'm not sure if that's going to last since they get middling reviews and are more of a gimmick or curiosity than anything serious.

The obvious option would be to try get ahold of a somewhat modern laptop and borrow the internals from that. But again that won't prove much since whatever i'd make would be specific to that one laptop. I like the idea of standard motherboard sizes and connectors since it gives room to switch parts out, say if I start with an old and shoddy NUC to see if it'll work and then maybe save up to get the latest greatest thing.

As for displays. There's all kinds of stupidly high resolution IPS displays about now. I'm still taking a look through them to see whats available in spares. eDP has really caught on and theres a bunch of guys making way more compact controller boards for them. I think it's more of a pass through for regular displayport with a few extra bits for lighting the backlight, and while that kind of stuff is well beyond me but they openly post their designs to copy. Then the digitizer boards from older displays easily disconnect from the display itself, and perhaps if I can find one that matches the display size or is a little oversized then it'll fit behind a modern display just fine.

Either way I think the next thing will be making that 3d printer. Rapid prototyping is what they were designed for!

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #67 on: August 12, 2018, 10:59:16 PM »
https://www.dfrobot.com/product-1728.html

Looks like this thing is set to release next month. It seems pretty good with built in eDP. Can't find actual board dimensions yet, but seems like something to keep an eye on. Edit: Dimensions are 79x115mm

I've also had no luck so far finding an affordable modern and relatively large IPS display with eDP. There might be a better way to serch for them, but i'm mostly trying to find various laptops and tablets that use them and looking up spares specific to those to then find the actual panel number from.

However the 9.7 inch ipad 3 & 4 displays are extremely available and relatively cheap. I guess because they sold so many there's skips full of broken ones to pull spares from. And this digitizer I already have is about the right size to match, being just slightly bigger. Could be a good way to assemble a more portable tablet.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #68 on: August 13, 2018, 01:58:51 PM »
Back to reality for a bit. Had a hard time sleeping last night so with the car in the garage I kept myself moving so I wouldn't calcify, and got a bunch done.


Made a stand and stuck that screen protector on. Went for a more upright stand (60 degrees) since it leads to a more comfortable posture than hunching over the thing. I put some rubber feet on the stand and with the weight of the device it doesnt move at all.

I also had it apart to drill holes for the two connectors at the top and... what a chore. If I thought a bit ahead I would've realised I could just put the connectors in the base and save myself having to drill some large holes in sheet steel with an incredibly fast but low torque drill and the wrong kinds of bits.


No matter what I tried I couldn't get all the dust off. I think just the act of wiping the screen was statically charging it and every speck and shard in the area flew onto where i'd wiped. This image also shows how the screen protector blurs the image a bit, but in a way that hides the pixels and gives it a cool look.


Messed around with the display settings a bunch and it vastly improved the image. The camera of course doesn't pick it up well but by default the greys were appearing extremely blue. Not as blue as in some of the photos though - I just forgot to hit the white balance. I'm also surprised that laptop can handle Krita's ~fancy brushes~. They give me a bit of trouble on my desktop if I go wild trying to fill an image with a complicated smudging brush so I didn't think the laptop would handle them at all, let alone as well as it does.


It also tucks neatly under the stand. This wasn't by design but i'm glad it fits!


I also cut apart an old test glove I had sitting on the desk to make one of those goofy tablet gloves. I thought they were for pedantic people that didn't want to get grease on their display, but it turns out it really helps stop your hand from chattering along the display surface.

So i'm back to feeling pretty pleased with how this is turning out. At some point I need to try program the arduino microcontroller to emulate keyboard shortcuts. It's soldered up but I don't know if it even still works. It was playing up last time I tried using it to mesure a potentiometer.


Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #69 on: August 14, 2018, 06:46:53 AM »
Boy i'm no good at scripting. What i've managed to create is a very dangerous USB device that when plugged in immediately starts hammering undo as fast as possible. I think i'm going to have to try disable the shortcut so I can actually reprogram the board.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #70 on: August 14, 2018, 09:11:34 AM »
Turned out the trick was to save and exit so there was nothing to undo before uploading the new program.

Seems like i've made some progress though. All my troubles were caused by a stupid syntax error in the if statement that made it ignore the query and just spam the function inside as fast as possible. I was puzzling over if the device was broken since I had a real hard time in the past trying to read a potentiometer value. So now I just need to copy this function 20 times for each shortcut I want to slap in.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #71 on: August 14, 2018, 11:17:12 AM »
Nice. Now it's working for reals. Got undo and redo set to keys. The problem I had is that theres a function to start the keyboard press, and a function to end that keypress. But because alot of the key combos share a key (ctrl) then having each individual function doing its own 'else - end key press' thing was mucking it up. So now i've got a bunch of integers to keep track of if a key has been previously pressed before running the release function once.

Or something. I'm not great at programming.

Now I just need to figure out what shortcuts are worth assigning to buttons.


Since the thing also works as a plain old digitizer with the display off, i'm considering the idea of ditching both my second desktop monitor and the old graphics tablet and using it to fill both roles. I'm always fighting for desk space so something you'd need to slide around and drag through the piled up junk wouldn't be ideal. Perhaps a cantilevered arm. But even if you could lock it it's not going to be very solid. Gives me something to think about while I type out this stupid function 15 more times.

Offline S. Heslop

  • Hero Member
  • *****
  • Posts: 1104
  • Country: gb
  • Newcastle Upon Tyne
Re: DIY tablet computer, maybe.
« Reply #72 on: August 15, 2018, 08:05:41 AM »
I've been all about trying to find a damned displayport cable with no success.

It's something I get hung up on actually, that physical shops never stock anything small that they wont be selling at least one a day. But they could just shove one of them in the store room or on the bottom of a shelf and it'd justify my trip out and maybe make me want to visit that shop again. They're all wondering why the internet has killed the highstreet but the internet is innocent of that crime - the highstreet committed suicide.

That said I enjoyed the trip out just driving about. There's a new radio station thats some combination hospital and student radio, but I think they might be breaking the law since they're playing Good Music.

Offline Will_D

  • Hero Member
  • *****
  • Posts: 573
  • Country: ie
    • National Homebrew Club of Ireland
Re: DIY tablet computer, maybe.
« Reply #73 on: August 16, 2018, 08:39:47 AM »
There's a new radio station thats some combination hospital and student radio, but I think they might be breaking the law since they're playing Good Music.

I highly recomend Radio Nova in Dublin - plays our sort of music! Any station that plays Thunderclap Newman and the Doors has to be #1

https://www.nova.ie/radio-player

Will
Engineer and Chemist to the NHC.ie
http://www.nationalhomebrewclub.ie/forum/

Offline sparky961

  • Hero Member
  • *****
  • Posts: 839
  • Country: ca
Re: DIY tablet computer, maybe.
« Reply #74 on: August 16, 2018, 06:12:38 PM »
I'm not great at programming.
...
Gives me something to think about while I type out this stupid function 15 more times.

Number one rule of programming: Avoid duplication. :)