Our GUS Simpson, upgraded with the latest parts, reached the stage of printing the official Simpson Test Squirrel tonight. He still has some issues to be resolved, but I’m very pleased so far. . .
This is one of the most complicated ways to print I have seen since I’ve started to follow 3D printing.
Nice!
How fast is this type of printer? I would assume it’s not faster than 30-40 mm/s.
@Nathan_O_Kane It’s less complex than you might think; each arm has four pieces (shoulder at the bottom, motor arm, slave arm, and hub) and the only vitamins required are bolts and ball bearings. There are no linear components of any kind, and as a result this design has one of the highest - or perhaps the highest - percentage of printable parts. If there’s another contender for that title it’s probably Simpson’s “brother”, Wally.
@Sven_Eric_Nielsen
I haven’t been trying to push this one yet; there are still some tuning issues to be worked on. But @Nicholas_Seward has run his considerably faster; this was the prototype, before the new and improved arms, but as you can see it’s moving right along: http://www.youtube.com/watch?v=IEGTe1G2Gqs
Is the speed governed by the heating up of the plastic?
@Bill_Owens
Thanks, that’s very interesting! This seems to have a lot of potential! Maybe I should jump into this game 
Do you have a link to a site with drawings and a bom? Until now I had no contact to this principle at all.
@Eddie_Palmer
Do you mean frictional heating of the arm parts, or the ability of the extruder and hot end to melt the filament? There should be very little friction between the arms, they’re designed with cycloidal teeth that roll on each other rather than sliding. And all of the bolted joints have pairs of 608 ball bearings inside. On the other hand, the extruder I’m using is somewhat limited, so that will be a cap on the top speed right now, it can’t push the filament fast enough. I’m going to switch to a geared extruder with a good hobbed bolt instead of the direct drive.
@Nicholas_Seward
What? I thought it an open source concept. Why do I have to pay for it? 150$ for a concept or and an assembly instruction. Really? Or do I misunderstood something here?
And the second link won’t work.
@Sven_Eric_Nielsen You must be looking at the bounties. Look at the desktop version and ignore the bounties. I fixed the second link.
Ah, now it works. Thank you!
Sorry bill but
It don’t know nothing about 3d printing but I running a bigger printing press and I print on paper and have to set the heart to the speed of the press and this is work out by how long the paper is in the oven and temperature when it comes out of the ovens what I have found the longer the ovens is better because you have more room to put the heat up.
Now with 3D printing the plastic most be heated up and the faster you go the hotter it as to get without setting fire to the plastic because I would get the same problem with paper that’s why I ask . Thanks for getting back to me best regards Eddie
@Eddie_Palmer The plastic being extruded needs to be hot enough to move smoothly through the nozzle at the tip of the extruder, and to stick to the previous layer that’s already cooled down and solidified. For the plastic we print with, the hotend is able to maintain the necessary temperature regardless of how fast the plastic is being fed in. It is not uncommon to use a heater cartridge that dissipates 20-40 watts, and it is only heating a tiny block of brass. Part of the goal is to only melt the plastic in a very small space as well; you want all of the filament above the hotend to be cool, so it doesn’t get soft and floppy, and all the melting to take place right down at the tip.
@Eddie_Palmer To add on to what @Bill_Owens said the limiting factor here is either the nozzle back pressure or the printers rigidity. What I mean is that as you push faster and faster the stepper that is pushing the filaments has less and less torque. At some point the back pressure will overwhelm the stepper. However, most printers aren’t rigid enough to produce accurate moves at the rate at which we can push the plastic.
Sounds like someone will have to redesign the nozzle with something like a cooler on the end because you are using the air to cool the plastic.
If you can speed up the cooling you will be able run your printer faster?
What about jets of CO2 on the plastic or something like this . I know this sounds bad ,but you could be the first to over come the problem because the one thing with the printer is the speed
@Eddie_Palmer Cooling of the actual part is only really a problem for very small parts. If you don’t let a layer cool down enough before you do another layer on top of it you start getting some interesting distortions as the part cools. Aiming a fan at the part is usually more than enough. The limiting factors here are the strength of the filament drive stepper and the rigidity of the machine. (Well it is actually a combination of the rigidity of the machine and the strength and speed of the steppers.)