Is the original design dead?

The direct drive one?
The discussions here and most attempts I could find are dated around 2010.
There are probably reasons behind this, but I couldn't find any clearly stated, so I can only guess -
too powerfull motors required? too hard to get good accuracy?
Thank you in advance.

I am not understanding the question.

Well, most of the designs I'm aware of use 3 linear stages, I was asking about this design, or rather, the reasons why it isn't very popular.

Many of those listed on that page aren't even 3d printers, they are delta robots. Those designs are extremely complex, fickle in nature, and often costly. Soem require more poerfull motors, which means electronics will be difficult, change the electronics and you need new firmware, which means writing your own delta code since only some boards are compatible.

The first practical, home 3d delta printer was the Rostock, which itself is pretty dated. The Rostock slides worked well, but you had to invest in some expensive slides and bearings to make it work optimally (same with the 3DR and original Kossel Mini designs), and the wood and mounting systems often led to calibration problems anytime you moved it or the humidity changed. All of which were why people have moved on from it.

The delta style 3d printer is relatively new, especially when compared with cartesians, so there was a lot of frantic early development, much of which wasn't practical or reliable. Things have sort of stablized at this point and we have a few good designs to pick from. Most people (including myself) recomend something without wood, and a bit more sturdy. My advice, build it as stiff and strong as you can, the stiffer it is, the faster and more reliable it will be. Also, figure out the largest size you realistically need, the larger it is, the slower it will be.


As for current deltas, the Kossel Mini (and slight re-designs), 3DR, Cerberus Pup, and if you live in the St. Louis area, the Griffin. There are more, but those are the designs I see or mentioned most. Most development lately has been in the form of sensors/sensing, force resistance sensors and auto calibration. For some fresh designs however, check out what Nicholas Seward is doing. I don't expect his designs to overtake the Kossel Mini as the dominant delta printer, but his designs are awesome.

Thank you for the elaborate answer. I find the direct drive delta the most fascinating design, that's the reason I was asking.
My intention is to build and program a controller and motor drivers myself anyway (I got attracted to 3d printers while looking for some embedded programming project to do). If it starts to look that I'm successfull with these I think I'm going to try building it.

You should look at GUS Simpson / GRD ;-)

Edited 1 time(s). Last edit at 05/06/2014 04:57AM by Mikadoh.

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georgi
Thank you for the elaborate answer. I find the direct drive delta the most fascinating design, that's the reason I was asking.
My intention is to build and program a controller and motor drivers myself anyway (I got attracted to 3d printers while looking for some embedded programming project to do). If it starts to look that I'm successfull with these I think I'm going to try building it.

Your entire printer will need to be custom.

Deltas like that cost a fortune for a reason. You need high speed, high precision, industrial motors and a system to run them (along with custom programming). This is all even more important if you expect a lot of speed. High speed alone can overload an Arduino board buffer, and stepper drivers are nowhere near strong enough for the motors you will need. Which means a full cnc style system ($$$$). I would expect to have 5k into it before you even see your motors move.

What many also forget, is the filament.
You will need to design and build an elaborate extruder system and possibly a nozzle. The pressures at high speed can be extreme, and while common stepper could possibly keep up, the hobbed pulley probably won't and will simply strip the filament. A larger nozzle diameter will help, but not solve it. You will also need a way to cool the previous layer fast enough, before the next layer is layed on top of it. This becomes a very delicate balancing act because higher speeds, often require higher nozzle temps to facilitate faster flow, but you need to cool the plastic faster and dissipate even more heat, and it goes up exponentially.

Once you cross 150mm per second on anything, it starts getting tough, and that speed is within the boundaries of many well built printers. By the time you crest 200, you start having severe issues with extruders skipping, low end pneumatic fittings can blow out, and vibration becomes an issue. On an Arduino, you also start hitting the buffer limits if you don't tune it. By 300, if your machine isn't perfect, forget it. In the last year, in a quest for better, faster printers, I have built 3 printers, used a dozen extruder designs, 4 extruder motors, 4 hobbs, 3 heads, destroyed half a dozen bowden fittings and frayed a set of belts. Most of that before I even broke 250mm per second. I can hit 300, but not very reliably, and from what I have seen on Youtube and in person, pretty much no one is even getting that. Speeds are highly over-estimated.

I would recomend you build a normal Delta first, you will learn a lot regarding the how speed effects things for only a small fraction of what the machine you want will cost. It will save you a lot of frustration and if you do decide to press on, you can sell that printer for what you have in it (if it runs, a working printer is worth more than the sum of it's parts).

You seem to overestimate my abilities by a large margin My XMOS startup kit is due to arrive today, and I haven't programmed a microcontroller, save for a brief exercize with a PIC some 10 years ago.
A great concern right now for example is how am I going to soldier the driver chip in TSSOP-38 package, seems I'll have to do a refresher how to make PCBs at home. I never was very good at electronics, doubt it I'll be better now.
In short, there is a long, long way for me to go before having something that exibits signs of coordinated motion, and I'm aware that I might fail and not get there at all. Things like speed and accuracy seem like concerns of the distant future right now. But a final goal is necessary and deltas kind of grabbed my attention.
I also have to keep the costs down, the biggest spending I already made by ordering three Vextas. Couldn't resist the temptation, even though realizing I might never put them to a good use or the choice of the particular model is wrong.
"Normal" deltas require additional spending for the linear motion, I guess this is one of the reasons I was looking for alternatives.
I have thought about the extruder design, and would love to experiment with it, but this is something that will have to be put aside for the moment. Your observations regarding extrusion and speed are worth a pinned topic I think, so more people could benefit by reading them.

Thanks again for the advices.

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georgi
"Normal" deltas require additional spending for the linear motion, I guess this is one of the reasons I was looking for alternatives.

The linear motion can be done cheaply with things like V-slot extrusions and wheels. If you follow the Deltabot Google group, there's a recent thread from Johann sharing his printable recirculating ball bearing that rides in a T-slot extrusion. I'm printing a set for testing now.....

You might also want to check Thingiverse for some early Delta designs that were direct drive, such as the Yazzo PolyBot.....

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georgi
You seem to overestimate my abilities by a large margin My XMOS startup kit is due to arrive today, and I haven't programmed a microcontroller, save for a brief exercize with a PIC some 10 years ago.
A great concern right now for example is how am I going to soldier the driver chip in TSSOP-38 package, seems I'll have to do a refresher how to make PCBs at home. I never was very good at electronics, doubt it I'll be better now.

Actually, I think i under estimated you.

Linear motion on deltas, as expensive as it can be (as mentioned, V-Slot!), dleta motion is actually cheaper than cartesians. The x and y axis on a cartesian are cheap, leading people to underestimate the real cost. It's when you price out the z axis that sticker shock sets in. I recently started working on an h-bot and got furstrated when it started to look like I could build another delta for 8% less. Mostly due to the Z axis ramping up the price.

Those motors are stupid cheap. Not sure how well or how fast they will run, but it's a good price. Watch out for slop in the drive train, as that could be an issue.

Good luck, and post pics.

Thank you, sheepdog43 and all who responded. I will sure post pics.