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I'm planning on purchasing a second printer, and I'm seriously considering a Rostock MAX, but I have many questions that I'd like to have answered before I make the purchase. Thanks in advance to anyone who answers my questions.

Speed and Stability:

1. How fast do you usually run your Rostock Max? The sales site says 30-60mm/s, but that's a wide range and I'd like to know what speed most people use in real life.

2. How robust is the frame? Am I going to see a loss in stability as the hot end moves away from the base? Does the stability change if I add weight to the top of the frame (multiple filament spools, books, coffee cups, etc.)?

3, Has anyone gradually added weight to the effector to see at what point stability issues are seen at high speeds?

Heated Bed:

4. My Mendel had issues with heating the bed evenly when it was just a PCB and glass setup. I saw a big improvement when I added an aluminum plate. How evenly does the bed get heated on the Rostock MAX? Is it worth adding an aluminum plate?

Automated calibration:

5. I've seen mods for automatically calibrating delta printers. How often will I need to recalibrate a Rostock MAX? Is automating the calibration something worth pursuing?

I run at all sorts of speeds. It really depends on the part. I'll do a slow 30 mm/s for high detail and small parts, and I've printed as high as 100 mm/s on larger and simpler parts. Normally 60-70 is my happy place with a .4mm nozzle.

The frame is rather robust, but it could be better. For a machine that's stationary, you won't notice a problem. If you transport your printer a lot or have it on a wobbly surface, you'll start to notice some motion artifacts.

I've got my extruder hanging by the delta arm mounts and don't notice any ill effects. I know that several folks have put their extruder straight on the effector platform, and I'm sure there's a speed limitation in there somewhere, but I haven't tested the limit on that.

You'll notice more even heat with an aluminum heat spreader plate. I personally think that the hot-spot caused by the extruder printing the first layer is a bigger problem than uneven bed heater, so I installed my heat spreader to mitigate that issue.

Automated calibration is the holy grail of Delta printing. Folks like MHackney and 626Pilot are very very close to having this figured out and baked in to the firmwares that we use. Other auto calibration routines have figured out bed leveling, z-height, and horizontal radius, but the newer generation of routines are very actively attacking the geometry errors and motion glitches that we see specifically on deltas.

Thanks for answering my questions. It sounds like an aluminum plate is worth purchasing, and I'll be paying close attention to MHackney and 626Pilot for updates.

Another question: Once I have the second printer up and running, I'm thinking of upgrading to multiple extrusions. I particularly like the Tri-hotend that Generic Default designed. (https://www.matterhackers.com/store/pri ... end-1.75mm) I'm having trouble finding many control boards that can handle more than two hotends. The only two options I've found so far is the Azteeg X3 Pro, or slaving two Melzi boards together. I've had bad experiences with the Azteeg X1 burning out stepper motors, so I'm hesitant to buy an X3. What other boards are out there that can handle 3+ extruders?

There are a couple that I know of. My X3 Pro has been completely reliable, but the Melezi+slave Melezi works, and the Duet with a X4 board works too. The Duet is a bit beefier when it comes to processing power. Theres also the RUMBA, the RADDS, and the Phoenix, though good luck finding a Phoenix, I can barely find much info on it. The RADDS is a Due based board (its a shield actually) like the Duet, so it a bit beefier. The RUMBA is very similar to the RAMBo, except it supports 3 extruders and it uses pololu style stepper drivers, so you can replace/upgrade them easily.

I'll have to check out those other boards, thanks!

How often do you need to recalibrate?