RostockMax ordered still some questions floating in my brain

[ApacheXMD]

Just ordered a Rostock Max kit the other day and am excited to get started. This will be my first 3d printer and after seeing 3d printing technology years ago, I'm finally (financially) able to dive into the hobby.

I do have a couple of questions I've been wondering about the Rostock.

Regarding calibration; I've read through several procedures for calibration and though it's a little hard to follow without having a machine to play with, my understanding is that you're just looking to have the print head almost touching the printing surface at three points when Z=0. This, in theory, will set the print head "parallel" to the print surface at that height. But what guarantees that the print head will remain parallel at higher Z heights? Are we assuming that the towers are perfectly perpendicular to the build surface?

Let's say one of the three towers was slightly out of plumb. If the three steppers are told to move up 100mm, your printing plane at that height wouldn't be parallel to the surface anymore, right? Is there a way (or need) to calibrate at two different heights? The geometry is escaping me slightly.

I also have a question about the heated bed. I've read that the reason you need a heated bed is to a) aid in adhesion to the bed and b) evenly cool the part during printing to minimize uneven shrink.

Once a print gets underway and is, say, 30mm high, is the heated bed even effective at that height? I would think that with over an inch of plastic insulating that layer, it can't be doing a whole lot for the top layers and that you're just keeping the bottom of the print warm. For even cooling, I would think that a fully enclosed printer would be the only option.

I sometimes see people print with a big fan pointed right at the print. Is this to cool the part faster to aid with overhangs? Would the heated bed be turned off with these sort of prints?

Thanks for any info, and I can't wait to get my Rostockmax!

-Kelvin

[Polygonhell]

The assumption of all the firmware math is that the machine is mechanically perfect, and the calibration assumes the same.
You actually calibrate at 4 points, 3 to guarantee a plane for a given circle and one to take out any doming in the motion.
In terms of a tower being out of plumb, assuming it's close the errors are in the 1/10th's of a percentile and swamped by other mechanical errors IMO.
The heated bed just keeps the bottom layers warm (just below the plastic transition temperature and prevents warping forces detaching the object from the bed, the ideal is a heated chamber, but Stratsys I believe has a patent on them.
Cooling is somewhat critical for certain types of print, those with sever overhangs or very tall small features in these cases you want the plastic solid as quickly as possible. This is particularly true for PLA which is far more liquid like than ABS at high temperatures.

[ApacheXMD]

Thanks for the answers! I got one more that maybe you can answer for me. Reading this forum and the reprap forum, I know to expect to experiment in order to get good prints.

Does one ever get to the point where you can look at a given model to be printed with a familiar filament, and fiddle with the settings based on experience, and get a viable print on the first try? Or is it a matter of experimentation with every print?

[mhackney]

Absolutely you can get to that point and it doesn't take that much time/experience to get there if you take a disciplined approach to it. You also build up a set of slicer configurations for different materials and types of part to print.

[Polygonhell]

You can get viable prints usually trivially first time, once you've dialed things in.

[ApacheXMD]

Awesome! This is going to be great!

Getting into 3d printing really feels like one if those milestones moments in human evolution. At least it feels like it in my personal evolution. The idea that you can physical hold in your hands an object that only moments ago existed only in your imagination, is mind boggling.

I haven't been this excited about technology since my brother got a modem for his 386 computer and introduced me to the online world (BBS's) back in 1991.

Anyway, thanks again guys!

-Kelvin

[cassetti]

Welcome!

I know how it feels - since dipping into 3D printing with a Replicator at work last September, I've been HOOKED! My mind keeps running a mile a minute, what else can be done? How can this improve my quality of life? Whatever happens, I fully intend to be a part of home 3D printing from the start, there's nowhere but up from here for this industry!

I too ordered my MAX on the 24th of February, it'll be delivered tomorrow! I'm actually probably taking a few days off from work to build it this week lol!

Fortunately, I have been playing with a Makerbot Replicator at work that was pre-assembled, and built my own printer from scratch last November. I will tell, you be prepared for a love-hate relationship at first. Until you get things dialed in, you will have a LOT of failed prints. Start small - don't print anything huge, delamination (warping) can be a major issue. Getting a flat print surface with evenly distributed heat is key for printing higher temp plastics like ABS and Polycarbonate. I have found that PLA is extremely forgiving. When my hotbed on my home built printer shorted out a month ago, I have learned how to print using blue tape exclusively with PLA.

It takes a few months to really get the hang of it, but once you do, you'll know right away what can an cannot be printed on your printer, and how to achieve those results through various settings in your preferred slicing application (slic3r, skienforge, etc). Just keep in mind everything is evolving rapidly. I believe the first open source delta reprap printers was only released in August 2012! You should expect to make modifications and upgrades to your reprap (or scrap it and use it's parts to make a better printer!), I've already ordered two upgrades to my MAX and it hasn't even arrived yet!

Good luck, be patient.

[ApacheXMD]

Heh, I've already ordered an aluminum plate from from mhackney and expect to do a lot tweaking. I'm an electrcian by trade and have built a few things before.

I built this motion simulatora few years ago for PC driving sims. It's not quite at the level of precision of a 3d printer, but it was a fun project.

So hopefully with some luck and help from you guys I'll be able to get some usable prints from my Rostock Max.

I'm like a kid waiting for Santa on Christmas! Hurry up UPS man!

[jesse]

Absolutely

Pun intended?

[mhackney]

ABSolutely.

[ApacheXMD]

Woohoo, delivery date is on for the 21st! Now to round up the last bits like RTV and ball head hex wrenches.

[leafi]

Hey mhackney
I was looking to buy one of your plates for the heated bed it said they are out of stock. About when will they be in stock so I can order one?

I ordered a Rostockmax and also included the glass plate. Would I still need the aluminum?

[mhackney]

leafi, fill out the little notification form on my site to get automatically notified. I don't have an ETA yet, it is determined by the level of interest.

[leafi]

Ok done. Will I need the metal plate if I have the glass one? How does the plate prevent the center of the onxy from drooping down?

[aehM_Key]

The center of my onyx was rising...

[mhackney]

The glass plate makes a fine build surface but will not spread the heat across the surface so You'll have hot and "cold" spots that differ by as much as 25°C. Also, the Onyx warps upwards when heated. I have had 1 glass surface break. While I can not correlate it 100% to the warpage I greatly suspect that. The aluminum plate solves both of these problems (it keeps the Onyx held flat). With it, you can print directly to it, blue tape placed on it, Kapton tape placed on it, or glass paced on it. The only reason I use the glass plate on mine is because I already had it! I print direct to aluminum and hair spray on my H-1 and it works great.

[MorbidSlowBurn]

I wouldn't necessarily say that the warping would cause the break. I would be more inclined to say that if there is significant variations of temperature in the glass (for example mhackney's 25C), high internal stresses can occur in the glass. These stresses can be fine with a perfect piece of glass but if there is a small scratch or chip the glass will most likely fracture. The aluminum plate allows for the glass to heat and expand evenly therefore minimizing the chance of high internal forces and breakage.

[mhackney]

Agreed, that is why I can not correlate the break to the warping. What I can say is that I've used this same glass material on a smaller bed on my H-1 for about a year now. There is an aluminum plate on this bed and it does not warp. I have measured the warp at the center of my Onyx at 5mm at 80°C. It changes though from run to run. I actually worked in the field of ceramic materials and did fracture tests on many materials. I know about stress risers, etc. Also, at the time the plate broke, I was doing a very conservative temp ramp up in 10°C steps so I wasn't just blasting a lot of power with the resulting temperature variations etc exactly because I was trying to measure the temperature variation across the glass and the time it took to stabilize.

It is very possible that both factors contributed to the fracture. In any case, what I do know is that the aluminum plate both evens the heating across the entire surface and it does prevent the Onyx from warping upward. Both result in a flat, evenly heated build surface.

[[email protected]]

i ordered the aluminum plate from mhackney and it is awesome. I had so much trouble getting the prints to stick to the glass now i have the aluminum plate i have had no problems getting prints to stick.