MakerBot Industries

Remember the video of the servo drive moving the bot? That kind of torque!

That's great… I really wish I could implement some servo driven motors like you did. I guess I have to wait for a MakerBot supported version, because that is beyond my skill level. I might be able to setup the hardware, but getting the firmware to support it all would be beyond me. Also, I really don't want to do any permanent modification, because I only have this one printer!

I just think we really need the ability to know where are motors are located, so if a step is missed, it can be corrected. Although, I haven't had problems with skipped steps in ages, with the open loop system. But, as time goes on and prints get bigger and stuff starts to move faster, we are going to need servos for sure.

as time goes on and prints get bigger and stuff starts to move faster, we are going to need servos for sure.

Actually, we need a machine designed with attention to mechanical and electrical detail. For example, that Tormach PCNC 1100 milling machine has a working envelope only a little bit smaller than a complete TOM's case, traverses at 40 mm/s, and has a 1.5 HP spindle motor… and uses microstepping motors on all three axes.

Of course, it costs $7500, but that's only 6 times more expensive than a TOM and it can do this:

for fast metal removal on 6061 aluminum we will run a 1/2” diameter 2 flute cutter at around 18 IPM (inches per minute) and 3000 RPM, using a full 1/2” depth of cut

… all day long, with no lost steps or histrionics. The accuracy and repeatability specs seem good enough, too:

Repeatability will be better than 0.001” per foot

Stepper motor performance definitely won't limit 3D printer for quite a while.

Oh, the Tormach also includes an embedded PC, high-power drivers, mechanical and electrical safety interlocks, integrated lubrication, and a whole bunch of stuff that's not even on the 3D printer wish list yet. I'd invite one into my Basement Laboratory, for sure…

Well, ok, then I guess we don't need a servo or closed loop system. :]

So, why are we headed in that direction exactly?

I did it because I'm going to school and was seriously upset over skipping steps. I knew that I could just go steppers, but chose to go extreme, and learned a ton on the way. Now that I "know" how to interface and use Gecko servo drives, my next project is going to be even cooler. My next two big projects are a CNC plasma table (already have the plasma and purposely bought one compatible with CNC), and my 90 watt laser cutter. The laser cutter has stepper drives now, so we'll see how noisy it is and possible upgrade it to servo (not the easiest but also not the hardest thing to do) to quiet it down. Since I don't have either machine yet, this is still a future project.

On the other hand, I purposely purchased 10 of the new motors to replace them in all of my bots. Being that I have 3 Makerbots-I needed 6 motors exactly, then the other 4 are for "future" projects and ideas. Knowing how Makerbot sells out of stuff that I need, i have resorted to buying in "bulk" to reduce shipping cost. Again, they nailed me buy releasing stuff on different days-and due to fear of how they sell out quickly, I had 4 different orders and shipments. At least I can hopefully say this, I have upgraded all of my bots to the latest and greatest. I'm hoping this is it for a while.

UPDATE
Don't be like me and try to overdrive the motor at 1.75 volts REF. It's not going to damage it but that's too hot given the little airflow to the X motor. I dropped to 1.65 for both X and Y motors. I'm sure somebody can be more scientific than I am about this.

Ya, I always run into the same stuff too… price you pay for being an "early adopter". Like when they released the Mk6, I bought it before they even got the blog entry about it up…. got it, and it came with the green nozzle, but people who bought later got the newer nozzles… so I had to go buy a new nozzle too. Then, right after that the Mk6+ came out… so I had to buy that as well. I don't regret that much though, because really the MK5 with that DC motor was awful. The quicker I got away from that the better.

Now I am going to buy these new steppers too. Do they have one for Z axis too?

I'm in the same boat as Ed and iv already said I see see no reason for over complicating the Makerbot platform with servos. When you have a properly powered stepper it will work beyond good for a machine like the Makerbot, and repeatability will often be better. Servos are not without there own problems either. But like I have said this debate can go on forever. A friend of mine who has a shop next door is running one of the Tormach's Ed linked too, its a work horse pure and simple.

Jetguy had a specific reason to retrofit servos to his machine, and its a cool project for sure. However it makes no sense for MBI to completely overhaul the entire bot and make it more complicated then it needs to be.

As Ed said mechanical and electrical detail and tolerances are where the bot needs improvement. There is just to much variation from machine to machine. Something will align one way on one persons machine but be completely different on another.

Renosis whats giving you the impression that servos is the direction MBI is heading in? Surely not those 2 encoders in the store that probably all of maybe a handful of people have purchased?

Let me add that the MBI servo driver board itself is not the solution "yet". The tiny H-bridge on those just isn't big enough. But it is useful and could be used on other stuff as-is.

And to be fair-servo was one of the "listed" features of development goals by MBI.
http://wiki.makerbot.com/roadmap

Although , they seem to have changed that page and removed the statement. I know they did say position feedback at one point in time.

Ahh never looked in there. Thanks for pointing that out.

Yeah, it was on the roadmap and those trapped nuts in the delrin layer of the extruder feeder. Those were meant for the rotary encoder. So, I just assumed that is the direction things were headed. Plus I've heard other people say it. And they hint at it in descriptions of items on the store.

I don't pretend to know what is the best direction or which way things should head, I am just a parrot who mouths things I hear other people say really. :]

I do like reading about this stuff though, because I am learning more and more every day. I just really don't have any practical experience with CNC stuff or anything other than with what I have done for 6 months on my ToM and trying to absorb as much as I can from the likes of you guys.

Hey, I started off about the same time you did, and this has been one of the best learning experiences. I learned more from this than 18 months of a fast paced engineering program.