Project Logs

Collapse

• [R] Laser Decision for Copper Sintering: 20W VF20

  kelvinA • 6 hours ago • 0 comments

  The BOM has been rather stable, with the only thing that I wasn't sure about being the laser. I was considering a 5W 0.08*0.08mm spot laser for the #SecSavr Soapavr [gd0146], but more research shows that a 20W laser with a sufficient spot size is the way to go.

  Firstly, I was looking at the cutting depth of stainless steel with these kinds of wattages, and it seems that 0.08mm thick is possible so that's good enough for me:

  Then, I was looking at the recently announced 30 - 48W lasers. Unfortunately, there's some issues. Some of them have spot sizes that are 0.1*0.15mm or larger, meaning that the kW/mm^2 is still at around 20W laser levels. Most of them are 750g or heaver, as well as having dimensions exceeding 60x60x130mm. All of them are near or over 2X the price of the ZBAITU VF20 that is possible to get under £300 on sale.

  The next video I saw was about copper laser welding, which is essentially what I'm trying to do here.

  One of the cool things is that the tests were done without shielding gas. Anyway, the below slide is important:
  

  The 450nm laser used has a dot diameter of 0.6mm. Thus, for a 1kW laser, the power density is 3.5kW/mm^2. As you can also see from the graph, 100um depth is achieved at 600W, or 2.12kW/mm^2, for a travel velocity of 50mm/s.

  The VF20 has been measured to output 21.5W, though the meter also says "Wavelength: 600nm" even though this is a 445nm laser:

  The listing on Aliexpress says that the spot is 0.1*0.08mm, but their website says 0.08*0.08. I know that, when it released, the spot was the former, and it's possible that, after almost a year of making these modules, they've been able to shrink the spot size to 0.08*0.08mm. 

  They've also got a similarly priced XF20 that has a 0.08*0.08mm spot size claimed in some listings and 0.06*0.08mm claimed in others. While I find the flame detection and laser crosshair useful, it's height of 130mm with the air assist inlet on the top (meaning I need even more height clearance) and weight of 700g makes it harder to integrate compared to the 80mm tall, 500g VF20. The XF30 also shares the same build as the XF20.

  Power densities of the options:

  Power (W)	Spot Size (mm*0.08mm)	Power Density (kW/mm^2)
  20	0.10 0.08 0.06	2.5 3.125 4.166
  21.6	0.10 0.08 0.06	2.7 3.375 4.5
  30	0.08 0.06	4.688 6.25
  32.4*	0.08 0.06	5.062 6.75

  *Assuming 5.5W diodes output 5.4W of power
  

  Conclusion

  Obviously, the main conclusion I can take from this is that anything under 20W is unlikely to work. It also makes a bit of sense, since 10W and 5W lasers have existed for a while and yet there are no 3D printers that use them to sinter copper, but these 20W+ lasers are very recent and so it's possible that printers that use them are still in development.

  It does seem like the spot size really affects the power density.

  Coming in at about £575, it's unlikely that I opt for the 30W laser.

• [A] SecSavr Soapavr [gd0146]

  kelvinA • 05/07/2023 at 13:09 • 0 comments

  The SecSavr Suspense is quite large and I think it's slowing down my development as I feel the stakes are higher. Additionally, I can't make much (if any) progress towards #SecSavr Sol^2 [gd0045] or #SecSavr Syrum [gd0141] without actual hardware. 

  I already knew about all this last year and that's why I started thinking about the SecSavr SuspenseSmall, but its phyiscal size (more important in regards to development) and BOM cost (less important) grew so large that it couldn't really fufull its initial goal of having something that can fit somewhere in a house (without having to plan for it like a new furniture item) for a somewhat paletable investment cost.

  Thus, I've created a new project:

  #SecSavr Soapavr [gd0146] 

• [R] Macrobase Bumblebee: Cheap 8 Stepper Motherboard

  kelvinA • 05/05/2023 at 19:28 • 0 comments

  So, after working on my multicolour FDM project, I decided to just aimlessly scroll AliExpress to see if there were any new and interesting products that I've never seen before, and I found a very low cost and low footprint motherboard, the Bumblebee from Macrobase:

  This is the kind of controller board I've been looking for, since the SecSavr Suspense uses so many stepper motors. It's much smaller (90 x 125mm) and cheaper than the MKS Monster, and could mean that I could opt for the £13.42 cheaper M4P instead of an M8P. I probably won't though, since the M8P is laid out more orderly. I've got to take wire management into account when making a motherboard decision.

  The M4P seems to have one more physical USB port (and not a header), but since I'm planning to have a lot of USB cameras dotted about like it's a mini-factory, I'll be using USB extension hubs anyway. 

  Anyway, 2 of those Bumblebee boards costs about the same price as many singular 8-stepper motherboards, so I'm just going to see it as a split-in-half 16 extruder motherboard and embrace the FREEDOM of going with as many stepper drivers as needed. I might give each stepper it's OWN stepper driver, putting the ones I'm most likely to need to tweak current values on the M8P and all the rests on 2+ Bumblebees.

  Oh right, I should mention that I'm going to be switching to 3 or 4 Z axis motors. Manual bed levelling should be a thing of the past, especially if aimed at consumers (though I'd imagine only prosumers would actually consider spending >£1500 on a Do It Yourself build).

• [T] Dual Stacked LCD to rival DLP sharpness?

  kelvinA • 03/17/2023 at 14:27 • 0 comments

  The idea DIY Perks tried was to place 2 LCDs ontop of each other to increase contrast levels. 

  It was suggested a few times by the community to have the 2 LCDs front-to-front to increase light efficiency as opposed to a diffuser between the first and second to unpolarise the light from the first one. 

  I believe the main issue for this application would be to make sure that the two panels are aligned to retain the 0.04x0.04mm pixel size. Longevity would also be a concern.

  The reason why I'm thinking of that higher resolution is because of colour dithering and PCB printing, where I'd ideally like crisp voxels of the correct size. If one pixel is 10um larger than it should be when printed, it means that the voxel for the subsequent material would be 10um smaller than it should be, giving inaccurate colours / trace widths just because of the material print order.

• [M] Up-to-date Concept Render

  kelvinA • 03/07/2023 at 20:30 • 0 comments

  This model is long overdue because the open-style SleepCinema idea was rejected a long time ago. As I mentioned in a TestCut [gd0139] log, I had an idea for a modern but boxy redesign.

  I model the actual thing really quickly (because I've only done the faces seen by the render camera) and then I look on GrabCAD for some castor wheels. After seeing a few, I think "You know what? I never liked castor wheels anyway. They're kind of large for heavy duty things and they don't respond to different movement directions all that well. This is a concept render anyway, so let's virtually spend £20 a wheel on some omniwheels!"

  So I found some omniwheels and it turns out that Fusion 360 can actually take CATIA files and turn it into something I can use in Fusion360.

  Made the wheels a light green because I like the look of it, added to the model, added a blue led texture to the base because I expected the box to look bland and took it to a render:

  The blue was overkill, but I then tried without any LED and it was expectedly dull. I then tried a more realistic white LED strip and I think I've now got what I was looking for: elegant, yet boring, but with a hint of modern interesting.
  

  Remember that interesting looking 3D printers are less likely to be "mass consumer" friendly, even though I doubt any mass consumer would be spending in the ballpark of £1500 (and potentially higher) to print AI generated 3D models.

  Lastly, add some handles and fillet the inside edge.

  Mn... not sure I like the look of that fillet. 

  I'll skip on the ergonomics for now. I do think the milky green looks quite peaceful and mind-clearing. Might as well change the wheels to more accurate colours since I can use the handles as the highlight colour.

  Copper looks REALLY modern and striking. The shorter FOV also helps. I think this is good enough for the final render after I reduce the length to 118cm (from 125cm). I've already reduced the depth from 60.5 to 57cm as I think it could be possible-- wait, is it? 

  No, I did the maths wrong and I need something more like 64cm.

  Final Render 1

  Wow. This looks SO much more professional and worthy of its £1.5K+ expected BOM pricetag. Print volume aside, you have to realise that my indirect competitors are printers like the RatRig V-Core, Prusa XL, E3D Toolchanger, UltiMaker (if you squint), Raise3D, Voron, Anycubic M3 Max and probably a few others. The printer should look like £2Ks worth of kit.

  Improvements

  Hmmm... I'm looking at cupboards and the handles are rotated 90 degrees from what I've got, and there's only 1 handle for cupboard doors the same size as the main door. Speaking of that door, it's only 60cm long and the expected max print length is 65.2cm. The door also needs airtight sealing around it, so I don't think getting under 1.2m is actually going to be possible unless the print area is also reduced. I also think 3 seperate doors is not going to be efficient (when sealing is added) and will have to switch to 1 long door.

  Doesn't look as glamarous but those are the ergonomic rules and consumer expectations that I'm not about to go against. Now I know it looks like 3 seperate doors, but it's actually 3 seperate tiles in a single door, since each tile is 60 x 60cm and the printer is now 64 x 128cm in floorspace.

• [P] Scaner cable works

  kelvinA • 02/20/2023 at 12:39 • 0 comments

  There's no clip on the sensor connector and you're just supposed to squish the cable in. The contacts are on the top of the connector whereas it's on the bottom on the breakout board. I got the cable where contacts on both ends are on the same side, conviniently meaning that the pinout markings on the breakout board match the pinout numbering from the previous log.

• [E1][R] Scanner sensor reverse engineering

  kelvinA • 02/19/2023 at 12:34 • 0 comments

  [19 Feb 2023, 12:00] I've spent the past 70 minutes finding continuity between the cable holder and the test pads, as well as any <100K resistances:

  This sounds like there's some vague agreement with this reverse engineering research on a much more expensive sensor. I think this sensor is used for monochrome scans so the RGB pins might just not be connected. Though, I'd still expect 1 of the 3 pins to have continuity as LED input power. Most pins outside the ones shown above are 20 - 40 MOhms and the NC has no continuity with any I could find. 

  Those 4 silver pins arranged in a vertical line are coated with some kind of thin transparent material that prevents conductivity. There are traces going to them, so perhaps this is where my mystery NC pins are going to and they just don't have their own test pads.

  The only thing I could guess so far is that pins 6 and 8 are ground.

  [13:50] I've found some more information in the instructions page of the aformentioned research. The project log one is on the left and the instruction page on is on the right.

  I didn't notice this the first time round, but pin 2 and 10 are apparently connected and I can confirm this. The updated map:

  I'm not really sure what's happening with Pin3, so I'm going to assume the left one is the more up-to-date pinout research.

• [P] Scanner sensor and cable breakout

  kelvinA • 02/17/2023 at 20:56 • 0 comments

  It seems that #Tetrinsic [gd0041] isn't going to be a thing that exists in a reasonable time frame, so I thought I'd get a cheap yet important part (Q8100-60002) of this SecSavr Suspense puzzle to work on in the meantime. I only need 2 in the printer, but when 2pcs cost £12 and 5pcs costs £17 and I could use some spares if I break any, it was an easy decision. 

  I only got 2 breakout boards though because I doubt I'd break that. Visually, I think I've got the correct pin pitch. The ribbon cable hasn't arrived yet so I can't check for certain.

• [T][R] 3D Printed Mechanical Relay IC Chips?

  kelvinA • 01/29/2023 at 01:29 • 1 comment

  So I was doing some light research to see if magnetless motors exist (they do) because, even in the best case scenario, I can't print magnets. In this hypothetical scenario, I can print copper and iron, where the latter is magnetic. Anyway so I was doing that and I found this project and I was like "Drats. I knew the SecSavr theoretically couldn't do it all. I already know organic matter isn't happening, but I can't print transistors!".

  But don't worry. This is a sub £2000 piece of kit. The world isn't expecting something that rivals Intel's 14nm++ process. This can be more akin to the fancy but massive redstone machines in Minecraft where it's amazing if it can be done at all.

  That's when I thought of mechanical relays. I didn't think too much about it until I heard that pinball machines used to use them... allegedly.

  So I then googled "smallest mechanical relay" and I got reed relays, which look like this:

  They indeed look small but I'm not a fan of the "inert gas", because I can't print that.

  Conviniently, Hackaday has an article about relays in computing. One of the things linked was a PowerPoint of microscopic relays, and these look interesting:

  I do wonder what kind of tiny scales would be needed to be able to use electrostatic force though... seems that later in the PPT it's mentioned that the gate is like 42nm or something. At least there was something about there being "no off-state leakage" unlike CMOS.

  The switching strip needing to move and also needing to be close enough to the contact(s) does pose a few print limitations if I actually want to compact them in 3D space. I'm thinking that a strategy is that I print temporary scaffolds so that the copper strip doesn't sinter-melt into the contact(s) and then use the laser to vaporise the scaffold. 

  Then, considering that I'm expecting the minimum copper thickness in this process to be 120 - 160um in XY and 80-120um Z, I feel like 1x1x1mm is actually a good target to aim for; it seems like a decent amount of space to get the stuff I need to fit. Thats... 10... 100.. wow that's 1000 relays in a 1cm^3 "chip". Even if the actual turns out to be 2x2x2mm, that's still 125 relays compressed in that cubic volume. Continuing with that 1K relay / cm^3 thought, and finding out that the Intel 8008 and MOS 6502 were 8-bit microprocessors with 3500 transistors, it doesn't sound like it'll be entirely useless to have such a relay density. 

  Printing the milli-relays also sounds a tad faster and more reliable than pick+placing thousands of the smallest transistors available. Again, this is a stretch-goal thought exercise and a lot of other stuff has to go beautifully right before I attempt the equivalent of Test Print: Nightmare Difficulty.

• [E2][R][M] Ideal Bed

  kelvinA • 01/17/2023 at 20:14 • 0 comments

  [17 Jan] Right now, the tool steel bed costs around £60 and the honeycomb mesh would probably cost another £60 if I could find one in the size I need. I did some research on r/lasercutting and the reasons for the honeycomb is so that the air stream has somewhere to go and the laser beam doesn't reflect back onto the cut material, allegedly. I also looked at the typical beds for top-down SLA's and it does seem that resin prints can tolerate quite large holes. 

  I'm thinking that a sensor will be needed to detect if the bed was able to move down to the max; this would indicate if it was able to push the boltheads through the holes in the bed or if a part or fixture stopped it. It could be as simple as a second endstop or as detailed as a load cell force sensor.

  Anyway, I found this video that shows that charring of the bottom side of the laser cut workpiece can be eliminated if the sheet is elevated. A commentor suggested ball bearings as a possible object too.

  Due to having tofirst layer cleaning, moving bed mass, auto ejecting and preventing laser reflections, it really seems that a bed surface with a large air:material ratio is the ideal bed choice for my application. Additionally, I was wondering how I was going to mount traditional PCBs for any PnP operations, and the holes would allow for a straightforward solution.
  

  Ideally, the hole spacing would be equal to the mounting holes of the MGN9 rail, allowing me to actually mount the rail directly to the bed underside. M3 bolts seem common enough, and their bolt heads can usually pass though a 6mm hole, so this measurement will be the minimum size. I feel like >=8mm would be ideal, allowing for some of the bolts to be misaligned.
  

  Here are M8 threaded holes spaced 20mm apart in an 8mm plate. There are M3 bolts on the very bottom of the Z axis travel such that when the bed goes all the way down, the bolts stick up through the bed and push off whatever is ontop. I can already see that there's still loads of surface area, so a more extreme 10mm spacing could be used:

  Alternatively, ths could be an excuse to use the hundreds of M8 bolts I bought that were planned for #SecSavr Sublime [gd0036]:

  In any case, I'd rather not have to manually drill 528 16mm holes into an expensive...

  oh right. The bed is larger now than when I last got prices. I probably should resimulate too, now that I think about it.

  Anyway, that number could be even higher if I can't find some industrial printer somewhere that actually can get away with holes so large. I found this model which uses 5mm holes, so an 8mm hole is probably in the realm of possibility.

  The holes in beds I can find on google images seem massive:

  And is it me or are they getting away with just a perforated sheet of metal?

  Ooo you can even get it in squares. It's a shame I can't seem to find some spare bed listing or something that indicates what sla beds are made like.

  Idunno about you but that looks A LOT like a perforated sheet with some backing grid. And every industrial printer is using it like it's the standard.

  For some, unexplained reason, 10mm and 20mm pitch just get skipped.

  Thanks Alibaba for telling me what this material is. It's 100% + verified + blue checkmark + no ratio stainless steel.

  I can't seem to find anything against using this as a bed material for laser cutting. Only issue I can see so far is that it's only 2mm thick max (and the ones I like are 1.5mm). How am I supposed to thread that? The good news though is that stainless steel should be 3x as stiff as aluminium, so theoretically a 2mm perforated sheet should be as stiff as 6mm of aluminium, right?

  I have no idea if this is going to work, but it turns out that "simplify" applies to all studies so I can't just remove the unsimulated bed.

  nope. Ok let's try "suppressing features" on the remove instances in the simplify

  okay...

  So for a 2kg load, I'm down...

  Read more »

View all 99 project logs