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I made some arms a while ago that are relevant to this thread. I put pictures on my Big Delta build thread but I'll repost some stuff here for convenience. IMG_1176.JPG IMG_1347.JPG IMG_1346.JPG IMG_1344.JPG This setup uses aramid/kevlar threads to hold the arms to the balls on both ends. The aramid...

So it's sliding on napkins instead of using rollers? But the magnets are holding the carriage to the rail? Not so sure that's a step forward.....At first I thought it was a contactless levitating system but it's not. Also, I'm getting tired of seeing pencil thin arms on delta bots, it kills any rigi...

Yeah for most 3d printers, NEMA 17 and NEMA 23 stepper motors work fine. We are limited in speed by lack of machine rigidity and hotend back-pressure anyway. Plus, you can get NEMA 17 steppers for like 9 dollars each with the stepper drivers costing only a few dollars more on pre-made control boards...

I recommend nylon or acetal rather than PTFE; PTFE has a very low modulus and creeps easily. I used PTFE cups on an older arm setup. Eventually the ball and magnet will deform the PTFE enough to make contact with each other, at which point you lose centering and the low friction. Friction of a ~5mm ...

I'm actually getting away from magnets for arms. They pop off too easily, which is one of the main causes of print failures for me. If you had a reliable system that you didn't mess with, they would probably be fine, but I modify my printer so much that it causes problems. I've been doing a lot of P...

I think the rotational type of delta is plausible for printing. We would need a few upgrades and design changes: 1) All rotational axes based on back-to-back preloaded ball bearings. No play, tolerances <<0.001, rigid, long operating life. 2) Thicker CF tube arms with aluminum connectors and joint f...

That's a really nice looking effector Heffa! I just saw your design on youmagine, I was about to ask about a ring to clamp down the groove but then I saw the one you designed. Looks great! Let me know how it works; as long as the hotend stays mounted on the effector in a rigid way, everything should...

Looks like the best printed pistol yet, makes me wanna design my own similar to that. Putting chamber sleeves and barrel liners in these things can really make them into more functional firearms rather than 1 shot assassin pistols. He stresses not to use PLA, but I've been doing some high temperatur...

Those things are built for speed only. They have big AC servo motors that allow them to go fast while keeping decent positioning accuracy, but they still aren't as accurate as our deltas. Plus, they need a rigid, precise top base for the motors and arms. I think one of the main problems with the rep...

I'm uploading a video to youtube that I just took of a single nozzle print in PLA at 240C; I'll put it in this post when it's uploaded. I only have two of three nozzles on my Rostock right now. For now I just have a few more pictures. Heffa, the reason it's hard to find things about the Tri hotend w...

The lathe is a 4400 from sherline. I made custom stepper motor mounts and couplers, that was before I even had any measuring tools other than calipers so the mounts kinda suck. The lathe has been a PITA since day 1, and I realized early on that the tolerances and quality that go into making a lathe ...

I was hoping to get stuff done this weekend but the cheap PSU wired to my CNC machines blew up. Not sure why exactly. I need to rewire all my things and fix my mill so it works reliably. Hopefully the smoothieboards didn't get fried when the PSU blew up, otherwise I'm screwed. Anyway, I got a few pi...

Some of the bigger parts of the machine need to be made from aluminum flat bar. The linear motion parts have to be aligned and machined without re-clamping, since they have to be accurate to within 0.001 inch over 12 inches or so. The surfaces need to be very very flat. Since I have a TAIG mill, I c...

The geneva mechanism never slips, and can be operated with a single stepper motor instead of a clamping mechanism (air, hydraulic, or solenoid) and a separate motor. Plus the repeatability is excellent. I can machine the entire geneva plate from one side using cheap aluminum flat bar. The live tooli...

So over the last few years of 3d printing I've come to the conclusion that 3d printers are capable of making complex plastic parts better than most CNC machines can. With the exception of round parts. Anything that needs to be very round must be made on a lathe or other turning type of machine. Even...

I finally mounted one of my Tri hotends on the effector. Looks awesome. I wish I had more than 2 minutes a week to work on this thing, though! At this point I have the machine moving at standard printer speeds of up to 150mm/sec. Next, I have to wire the hotend and test print, then install all of th...

Some metals like aluminum and brass don't really have a speed limit on machining. Others like inconel and titanium can only be cut so fast even with state of the art cutting tools. Some of the prints I've been getting recently look close to perfect, and come off the printer with flatness +- 0.002 ac...

I think a printer with subtractive capabilities would have to be able to cut any plastic or any material you print. The main problem I think would come up is the maximum holding force. Normally, parts being milled or turned are clamped in a chuck or a vise. On a printer, you would have to rely on th...

Plastic part tolerances are worse than metal part tolerances because plastics are typically 50-200 times less stiff than steel. And they change with humidity and temperature a lot more than metals. And most plastics creep over time. Real 5 axis CAM software is typically expensive, but the majority o...

I'm actually not as pessimistic as you guys about the potential; I think filament type machines will max out at tolerances of around 1 or 2 thousandths. I think a lot of the current inaccuracy comes from the machines being designed and built on price points more than performance points. We're alread...

As the post title suggests, I've come to believe that all additive manufacturing methods and machine types are inaccurate. I've noticed this over the last few years, but I was expecting it to improve and it hasn't. Most of the tables I check say something like "+-0.008" for the first inch,...

That would be a nice feature to have. Not sure if it would work for my big delta because of the lead screws, but belt/cord driven printers would benefit from a stall-zeroing system. If the detector is reliable enough you could effectively use it as a closed loop system. If it can only detect that &q...

Damn Arthur you have forum ninja response time syndrome . Smoothie Five-O be profilin' me. I have videos of the CNC stuff, I might have the original files on a camera SD but I transferred all my stuff to a laptop which has been unusable for a couple of months. When I was prototyping my Tri Hotend la...

I'm still glad I bought the smoothies, there have a been a few problems with them over the year and a half I've had them but they work great most of the time. I think I'm the only person driving a lathe with smoothie, and I haven't seen any 4 axis TAIG mills with smoothies either. The stepper curren...

Nope. The company I work for still regards it as strictly forbidden. I suspect it's because the company has many locations across a number of different states and will hold their current position as long as it's illegal at a federal level. Either that or they think "Reefer Madness" is a t...