So I bought a cheap 40w laser....


Some guy in the desert
Well, the project is officially taking at least a tiny step forward. OpenBuilds had a $25 on $100 sale for Christmas so I pulled the trigger on a couple of gantries, and a bunch of 2020 and 2040 v-slot.

Not enough to build the whole machine....but should be plenty to build the motion platform at least. I didn't want to buy too much since I haven't had time to draw out my plans in CAD yet, but didn't want to risk not buying enough either. I'll still need a bunch of hardware (screws, t-nuts, braces, belts, maybe some new steppers). I'll be buying cheaper Chinese T-slot or V-slot (whatever I can get cheapest) for the bed and outer frame. And while I'd like to cover it all in clear acrylic I'll probably just go with ply at first since it's cheap and locally available - but that's a few steps away still.

And I wasn't able to get the old AC removed and vent installed while my parents were visiting - so still need to find a way to make time to complete that project (honestly I have no clue where I'll even have room to work on this right now. May have to give up a bunch of floor space in the back room for a bit.

Thankfully I have the rest of this week off from work so going to try and find some time to do some CAD and start getting a plan together now that parts are on their way ;)


Some guy in the desert
So I haven't worked in OnShape much in the past year...and given how quickly these "software as a service" style systems update...and how I never really got assemblies figured out well in OnShape...and how OnShape's latest (almost 2 years ago now) licensing change means everything I do is public domain....decided I'll give Fusion360 a try again.

But before I dig in with the full laser motion system and assemblies and all that I figured I'd do something quicker and easier for another little project I'm working on.

Wonder if anyone can figure out what it is....I'd guess @dkj4linux might be able to figure it out.


The only hint I'll give right now is that I thought it might be fun to brush up on my programming fundamentals and that what I'm building was designed around the time I was born. So 3D printing the faceplate for it isn't exactly period correct. But I could always machine it on the MPCNC if felt like dealing with the noise and mess of that option.

The bummer is I designed it with those labels as separate bodies so I could do it as a multi-material print on my Mk3s/MMU2s - unfortunately they're too small and the slicer won't generate gcode for them :( I tried making them a bit bigger but they were still too small. So I'll have to give in and just fill them with some white paint or something.

Overall Fusion360 wasn't much different from OnShape. I'm not used to the pan/orbit controls (I know there's a way to change them to work like OnShape/Solidworks but I'd rather learn them as designed than change them - but unlearning muscle memory is harder than learning it for me so it's a bit frustrating!) Centering text like that was a bigger pain than I expected - but I eventually worked out an easy way to achieve what I needed. (I had to add an extra point centered on the bottom of the text, and another point where I wanted the text then make the two points coincident.)

But...this was also a VERY simple design and doesn't have any assemblies or moving parts. So we'll see what I think over the next few weeks as I dig in on modeling up my plans for the laser :D


Some guy in the desert

I guess next time I need to give worse hints :D

Yep. One of the very first home computers a COSMAC ELF. Growing up I had a C64 at home but was always fascinated by the blinking lights, switches and way people could actually interact with older designs that lacked things like keyboards and monitors. I dabbled in assembly in high school on the PC (mostly just enough to learn how to crack some simple copy protection routines) and later messed with PIC microcontrollers a bit back before picbasic and eventually arduino on avr made it possible to play with microcontrollers without knowing assembly.

But those old computers still interest me. The old Altair 8800 is something I've long hoped to find at a garage sale or fleamarket being sold by someone who didn't realize what it was and therefore not asking the kind of price they tend to fetch (which is more than I can justify for an ancient toy!) And that design is a bit complex for me to tackle building from scratch. You can get a modern clone for $620 (the same price the original sold for) but again - more than I'm willing to spend. You can get an Altairduino for $180 which is a bit more reasonable...but it's basically just an arduino mega with a fancy panel and case. And the old hardware fascinates me as much or more than the actual "computer" itself.

So a few weeks ago someone in a radio project I follow noticed that BG Micro had the RCA COSMAC CDP1802 chips for $6 which piqued my interest. I hadn't heard of the ELF before but found it's minimalism interesting. It was designed (buy one of the designers of the 1802 chip itself) shortly after the Altair and was released as build it yourself plans in the same magazine that announced the Altair just a few months earlier...but while the Altair went for $600 (The equivalent of about $2,700 today) the ELF could be build for a mere $80 (About $350 today.) The Altair is a more complete and capable design...but the CPU in the ELF is arguably as capable or more then the 8080 used in the Altair (though admittedly slower.) The ELF's main weakness was the lack of a common expansion bus design like the S-100 MITS used on the Altair.

There are quite a few people who expanded on the basic ELF design to create far more capable machines. And the 1802 chip itself is actually still in production! Though the current production is a much more expensive radiation hardened version used in military and space applications. It was even used in the Hubble telescope and Magellan Venus probe!

So for $6 it seemed like a fun little chip to play with. A bit of research showed a recent (2017) recreation of the ELF along with parts lists from DigiKey and Jameco showing that it can still be built. Finding the original display chips used is a bit tricky...but there are nearly identical replacements that can be found on ebay. The 1802 itself is the other tricky component to find - but finding that was what started me down this rabbit hole :D

So, a few orders off ebay and one each from jameco and Digikey and later this week I should have all the parts I need to build one. All told it ran me just over $200 for the parts (not counting wire and things I have on hand like wood and perfboard.) Most of the expense is actually the switches as I opted to use the nice high quality ones the guy who did the 2017 build used. Over $60 of the cost is switches. I suspect back when the ELF was originally designed the switches would have been the cheap part and the silicone would have been most of the expense :D But silicone has gotten cheaper and mechanical parts have gotten more expensive - go progress!


Troll Spammer
The switch panel really gave it away for me. I started out in the mid 70's on a Rockwell Aim-65. I remember upgrading the Aim from 1K to 4K wondering what we would do with all that extra memory! It had 8K of basic interpreter ROM, 4K assembler ROM, and quite a bit of good stuff for learning the foundations of computing. We had EVERY issue of BYTE magazine, along with all the other geek mags of the day, so the ELF and all those other "personal" computers of the day are stuck in my memory from all the ads in the back of those mags. My Dad used to bring other stuff home from work for "training", and I'd end up spending more time playing with it than him. I thought about grabbing all the 70's stuff from my Mom and Dad's place when they were downsizing from their home of 60ish years, but in the end, left it all for the auction. I have too much clutter already, and cleaning up all their clutter made me realize we didn't need to add all that clutter to our clutter. LOL Probably could have got more selling it outright on ebay, but there were other things going on that really made that a non option. I had access to the 8080, 8800 and other "switch n lights" boxes, 8" floppy stuff, etc... Timex sinclair, TI99-4a, C64, etc. etc. etc....

FYI, if you need any 2112 memory chips, I probably still have a sleeve of those somewhere in the basement.....


EDIT: Digging through one of my old bins... This was on top
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Some guy in the desert
Nice finds @LitterBug! Could have saved me $11.90 if I'd known you had those stashed away ;) But I'm using the 5101's instead since they're a drop in CMOS equivilent...and since the rest of the circuit is CMOS they're kind of a better fit anyway.

That AIM-65 would be luxury compared to the ELF :D 1K of ram! I'll have a whopping 256 bytes to work with on the ELF. Of course with no way to preserve a program across power reset and having to manually key in the binary for each of those bytes with the 8's not like I'd ever want to try using all 256 bytes :D

Though there are people who've upgraded the ELF to have ROM and serial for loading programs. There's even a setup for a version that fits in an altoids tin and can use arduino shields! That's only $89 for the complete kit: But being built on circuit boards instead of wire wrapped by hand it doesn't feel quite as vintage ;)

If you have more of those PE's you're just a few months away from the ELF - August of 76 would be the issue to find. I'd love to come across a stash of those old 70's electronics mags one day. Could probably dig up scans on-line but I like holding actual mags still. I still have a bunch of late 80's early 90's computer mags I keep around just to flip through when I find them while cleaning. Love the old ads :D


Troll Spammer
Yeah, if this was last year, I could have gotten you the whole collection of PE and tons of other mags as well. I have one more from 78 in my bin.



Some guy in the desert
So still waiting on my parts from OpenBuilds (they were scheduled for delivery this Friday but got a notice from FedEx this morning that they may be here today!)

So at risk of pulling my own thread too far off track I'll share a little ELF progress. Despite ordering parts from two retailers and about 5 different e-bay sellers they somehow all managed to arrive at the same time yesterday. So now I'm at the "what have I got myself into" point of this project :D

I consolidated all the various orders into one looks pretty intimidating but I keep reminding myself that it's really mostly packaging:


I may wind up doing an aluminum and wood "enclosure" after all like the original design. Here's a close up showing how the 3D printed labels didn't really work out due to being too small. They are there - but are almost impossible to see because of how small they are and the lack of color. Since the text is too small to actually print itself I thought maybe I'd try embedding a block of white inside the part hoping the white would show through...but for some reason prusa slicer is just refusing to play nice with that too and I ran out of time trying to figure out what I did wrong in the design last night. Since my MMU is still finicky and I don't fully trust it I was ok with that.

I did however decide that if I was going to print the face plate then why not just print the whole frame? So I did a bit more work in Fusion and added the rest of it. I did make a few mistakes though:

Sorry for the fuzzy photo - didn't realize it focused on the background when I took it. The mistakes i know I made so far are that I made the hole for the audio jack the wrong size (for some reason I sized it for an RCA jack instead of a micro phono jack) and I sized the holes that the perfboard mounts with for wood screws. Which would be fine if I was screwing into wood. But...what I should have done is sized it so I could use M3 screws with captive nuts from the other side.

Note a huge deal because even if I use this I'm going to have to reprint it at least one more time. But...I'm also not sure I even want to try. It's a 6.5 hour print and while you can't tell from the photo I consider this one a failure. The lower right corner warped while printing. I was afraid it would. Long skinny things like the sides and bit flat plates like the face are more likely to warp. The black filament I currently have is from inland and while it usually prints decently every black filament I've tried has been more likely to warp than other colors it seems. So - filament that's more likely to warp with a design that's more likely to warp I wasn't shocked to have it happen.

But...I'm itching to start building and don't really want to mess around with more printing at this point. I may just dig out the table saw and rip down some scrap oak I have and use the initial print of the face plate by itself that I did.


Some guy in the desert
Well my parts from OpenBuilds came today. 4 meters of v slot 2020 and 3 meters of v slot 2040 along with 3 gantry kits. Assembled the three gantry kits - and learned that the last two I assembled (and used on my old 3d printer) I assembled wrong! The last time I used these it bugged me that the screws seemed almost to short...and when I tightened them it cinched the bearings too tight. So this time I tried to look for instructions (I man card is in serious jeopardy!) turns out they don't have instructions for the gantries...but they do for the wheels themselves and it's just a short youtube video (I HATE video instructions, give me diagrams and written instructions any day, I don't have the patience for video instructions that don't move at my speed!) Turns out one of the "precision spacers" is meant to go between the two bearings. Which makes a lot of sense to me know that I see it. I always thought the second spacer seemed superfluous on the outside against the spacer!

So, got my three gantries assembled and have a pile of rail. Guess I need to get serious about drawing up my plans now and getting a motion platform built. I will have to place at least one more order for things like idlers, pullies, belt, and probably motor mounting plates. I could print some or cut some on my CNC...but I like the metal ones so will probably put down the cash for them. However I do plan on printing a lot of things like corner brackets and other mounting pieces. Just the higher stress motion critical parts I'm going to go with metal. I've used 3D printed corner brackets before though and was very happy with them so don't mind using them on this.

My one big complaint about OpenBuilds is how over packaged their stuff is. Just look at how many baggies I got for one gantry:

That's a completed gantry on the left...and an uncompleted one with all the bags it comes in on the right. Even the two empty bags are from the unassembled one. The four wheel kit bags were in the bag on the bottom and then all the rest was in the plain bag. It does keep things organized...and I'm sure a big part of it is because they sell the wheel kits separate so they're probably packaged already before being put into the gantry kits...but still it feels so incredibly wasteful.

I also made a bit of progress on the ELF. I decided to go ahead and print the frame again. I made the labels almost twice their original size and changed them from Ariel to Helvetica (which is what they were on the original) which finally got them big enough to print...kind of. . I also made the switch holes very slightly larger - they fit before but were a tiny bit snug. I knew the labels wouldn't be perfect...but wanted to see if they'd print at all. And they did...and look wrong almost exactly how slicer predicted they would:


Oh, I also rounded the front a bit just for aesthetics. And I printed it with a brim this time which successfully stopped the warping - but slicer used white for the brim (and I can't find any way to tell it which filament to use for the brim) so there's a little residue left from it that I'm not super happy with.)

I also added nut traps and made the screw holes large enough for M3 screws:

However I made the traps just a tiny bit too large - they work...but they aren't quite as snug as I'd like. I also made them a little shallower than I wish I had since the screws I have on hand are all either too short or too long to work right.

So moved the switches over to see how this new version looks:

Better. And I could live with it. But...I'm going to try one more print tonight. I switched the font for the labels to be bold which now has them looking better in slicer. They're still small enough that they can easily get damaged while printing...but I think it's worth a try. Plus I made the nut traps just a tiny bit tighter and a few mm deeper so I can use shorter screws to mount the perf board.

Oh - and I learned I'll have tomorrow off now. So I'll probably have time to cut the perfboard to fit, mount it up...and if I'm feeling brave maybe start doing some wire wrapping!

And if I'm not feeling that brave then I can fire up Fusion 360 and get back to the laser this thread is actually about ;)


Legendary member
And if I'm not feeling that brave then I can fire up Fusion 360 and get back to the laser this thread is actually about ;)
You know...
I was going to mention that a laser (same one the thread is about) would be great for creating that face plate for you... ;):LOL:


Elite member
Dang! Turn my back for a few days... and it's the 70's all over again? I thought I was gonna wake up to the year 2020 and... well, I'm confused. Maybe I'm closer to being institutionalized than I thought. Way to play with an old man's mind, guys... or, what's left of it anyway. :eek:;):eek:;):eek:


Some guy in the desert
Just trying to keep you on your toes @dkj4linux :D

And yes @kilroy07 I could make a plate on the laser (even as it's currently setup) but engraved labels on Acrylic wouldn't work well...and I'm just not a fan of charred wood for labels either. Plus the laser is still too much of a pain to use in it's current configuration. And I'd have to dig out the table saw to make the frame.

Thankfully third time at printing a frame as the charm:


Making the labels twice their original size and using Helvetica Bold instead of Helvetica finally made them large enough to print legibly. And I quite like the texture from my powder coated PEI sheet on the MK3s.

So, finally cut down some perf board and mounted it up. I did make the nut traps a little smaller and deeper...but apparently should have made them even smaller. They work...but I can't tighten the screws quite as much as I'd like without the nuts turning in the traps. (3M nuts are nominally 6mm across so I originally used a 3.2mm diameter inscribed polygon to leave some room for error...I dropped it to 3.1 still giving .2mm of slop...guess I need to go with just a straight 3mm diameter though if I want them to fit snugly...not worth reprinting over though!)

Then I dropped in the sockets according to the plans:


Looking pretty good. I'm still missing the cap for the IN button, it was backordered. I may print one up to tide me over until the real one gets here. And I really should have ordered some spare switch caps. If you look closely you can see the #7 switch's cap is split just from being pushed on...You can't see in the photo but #4 and #0 are also splitting :( I even used a little bit of lubrication on them when installing.


So it's coming together. Have to go work on some other projects but maybe tonight I'll work up the courage to put my wire wrapping tool to the test.....


Some guy in the desert
I promise - this will get back to the laser cutter at some point, I can't keep tripping over $200 worth of v-rail and gantries in my dining room too much longer :D

But...I also still wanted to get more familiar with Fusion 360 to model this thing up before I start cutting rail. The ELF case taught me a lot but it was pretty simple and didn't cover a lot of things I need to figure out.

The ELF is also slowly making progress. I started wiring up the power supply and grounds:

The wire wrapping is more fun than I expected. Took me a few tries to get the feel for how long to make the wires, and how much to strip them but I'm starting to get consistent results.

But...back to my other practice Fusion 360 project.

Over the summer I got back into playing with HF radios again. And I wound up dusting off my old PSK-20 rig I had built about a decade ago only to find out that there's effectively no PSK activity on 20meters anymore :( Looks like everyone has moved on to a hot new digital mode "FT8". The details of FT8 are WAY off topic for this already off-topic thread - but basically it's designed to get messages through in VERY poor a compromise it doesn't allow for much actual communication. Transmissions are only 15 seconds long and highly structured, don't get to share much more than your call sign, location, and signal quality of the person you're responding to. There's a modification to it called JS8 which allows actual conversations but the radio I have setup for doing FT8 is a bit of a pain to configure for JS8 since it's a SDR and FT8 is built into the software I use to run it but JS8 requires configuring virtual audio cables to run an external program.

Long story slightly shorter - the guy who designed the PSK-20 retired from radio kit design years ago...but another designer recently talked him into coming out of retirement and designing a rig for FT8/JS8 which they released late last year. At about $60 I had to give one a try:

And as an excuse to continue learning F360 I decided to 3D print a case for it:

It works...but I'm still fine tuning it:


The front is incomplete...I need to add two pushbuttons and a 3rd LED hole. I just can't find suitably small pushbuttons I like and I don't want to have to make a small board to support tactile switches with 3D printed actuators. So still debating how to finish that.


Also not 100% happy with the way the rounded sides print. I love the look of it, but even with supports it doesn't print super smooth. I could go to smaller layers but it's already 8 hours of printing for the full case. So I may just square off the case sides.

I designed it so all four "sides" print against the print bed so they get the nice textured look from my Prusa powder coated bed. But right now the same screws that hold the case together also hold the board in place and that's a bit ackward. I want to be able to remove the top for easy access to the board without having to undo screws or undo the board mounting. So...I'm working on a tweak to make the top snap on/off instead of screwing on/off.

So far I've learned a LOT more about F360 with this. And am super glad I took on a smaller project like this first as it's taught me a lot about organizing a design in F360. Plus even this little design got a bit messy in F360 so I know a few things to avoid in the future.

If anyone is interested the F360 project is here:

Well, progress with gaining familiarity with F360 continues which I'm counting and progress towards completing the laser...or at least starting on it :D A few more weeks and I'm hoping I'll feel confident enough to start working on drawing it up.


Some guy in the desert
I hate doing the same thing over and over. It's a terrible pet peeve for a creator though because that's a GREAT way to learn things. And when I do suck it up and re-do something I'm always amazed at how much better and easier it is the second time.

Instead of just tweaking my existing design I basically decided to make a new case design from scratch. I did cheat a little and used the first versions front and rear panels to place the holes in the case and height - but otherwise redrew it from scratch.

And found that I was able to do so MUCH quicker with far fewer issues than the first time. Apparently this old dog can still learn new tricks :D




The biggest change I made was to the profile. Instead of using half circles for the sides I used some squished arcs. This made the case just over 1/2" narrower overall and with the steeper profile to the sides they print a lot cleaner without support now.

I also added some vents over the main drive transistor which can get pretty warm and give the case a bit more visual interest. I got a bit fancy on the front panel and fired up the MMU on my printer to make the text stand out. But most importantly I redesigned the lid to be a snap fit.

It's easier to see if you look at the 3D view on fusion, but I basically shaped the edges of the case halves so they interlock with the top being squeezed together to make it latch. Ah heck here's a photo to show how it works:


That also shows the test pieces I used to test this mechanism. It's so small I wasn't sure if it would print well enough to be usable, or if it would print at all - so I made some short test pieces and printed it in both orientations to compare:



Printed on edge the curves came out a little nicer...but the top/bottom finish while not bad just didn't seem as "finished" as the texture from the powder coated build plate gave. And the locking parts seemed to work equally well printed in either orientation so I stuck with laying the top and bottom case halves flat on the build plate.

But when I went to assemble it with the front and rear plates I ran into a problem. The top couldn't flex to snap in place because the front and rear plates fit too snugly. I could have made the front and rear plates a little looser...but I didn't want them to rattle. And I could have cut some reliefs into them...but thought about it and decided on this:


The lock is cut off of the top on both ends for the first few mm's so it doesn't have to interfere with the end plates. But even after doing that I still had to add some small reliefs so the center of the top could squish in and lock in place

The gap there is on purpose - same reason there's one on your TV remote - it helps hide any small imperfections in the fit between the two case halves.

It's still not perfect. I probably will make the end plates just a hair smaller so they fit a bit looser and I may make some tweaks to the top to make it easier to install and remove. Plus I still need to finish adding the two buttons and an optional 3rd LED hole to the front.

But it's good enough I posted it to thingiverse and prusaprinters

And that redesign gave me a LOT more confidence with Fusion 360. I still want to do something with some moving parts before tackling the laser cutter design...but I'm definitely getting closer to tackling it!