Rostock Max at First Glance

The first thing that caught my attention when researching the Rostock Max was its large 11" diameter build area. It's also a very cool 3D printer. It is a Delta printer. Delta printers use three vertical arms to position the platform (delta base) over the build surface. Due to the leverage gained by the arms and the end effectors the delta base can move very fast. The arms are via special linkages to the delta base (effector plate). These linkages are called effector links or end effectors. The arms are kept parallel so that the carriage movements can be translated into X, Y, and Z movements of the delta base. The fact that the carriages and motors are not mounted on the delta effector plate allows for a very nimble machine.

The Rostock Max is only available in kit form only. It comes packaged as shown below.

The Rostock Max is made from 1/4" melamine coated MDF. Assembly was not difficult, but it did take me several hours longer than was indicated by SeeMeCNC. That said you will spend much more time tuning the Rostock Max than building it.

You can find the assembly instructions here:

Rostock Max Assembly Instructions

While the assembly manual for the Rostock Max is better than most, it does not include the instructions for the included extruder. The extruder instructions are currently only available in the form of a very low res series of YouTube videos.

Rostock Max Extruder Instructions

 

Tools needed

These are the tools that I used in one way or another to assemble and adjust the Rostock Max 3D printer.

While you may not need them all, you will need most of them.

Most of the 3D printers have one issue or another, so it would not be fair to single out the Rostock Max as a bad printer. I will simply point out the problems I have encounter while using the Rostock Max. At the end of this review I will give you my final thoughts on the Rostock Max.

Hot-End Assembly

I feel it's important to note that you will need some RTV Silicon gasket and Kapton tape to assemble the Hot-End. These are not included.

Controller

The controller used on the Rostock Max is a Rambo board, shown above. This is one of the most powerful and versatile boards available for 3D printing. It has a separate power input for the heated bed so you can utilize a power source different from the source you use for the controller.

In addition you can add an extra extruder, as well as additional sensors and fans.

Early Tests

After assembling the Rostock Max the instructions will take you through the wiring of the controller, the configuration of the software, and some calibration steps.

After the initial recommended calibration, and before my own calibration I like to take the printer for a spin to see if the settings are in the ball park. One of the first things I like to print is the hollow cube (Thingiverse 5011).

Well, as you can see the first print (above) was a complete failure. Several things contributed to this mess. First, the bed height was not properly adjusted. Second was an extruder jam because the tension bolt was not tight enough.

After setting an offset in the slicer software and tightening the tension on the extruder I was able to achieve the above print. Not bad for a first print on a delta printer.

I made several more prints (shown above) and started calibrating the filament. My first calibrated print was Mr Jaws. (Thingiverse #14702)

This is a good test and will yield you a cool print that you can give away. Its a potato chip bag clamp. Its used to hold the bag closed.

At first glance Mr Jaws (above), look OK. A little cleanup and you have a functional part. Many would be very happy with the print. My problem is that own several other second and third generation 3D printers. I know what can be achieved when the printer and software are in-sync. The photo below shows a perfect printed Mr Jaws. It was printed on an Afinia printer.

I traced most of the problems with the Rostock Max back to the extruder/bowden/hot-end assembly.

If I print an object like the stretchlet shown below, the print comes out perfect. This is because this print requires no filament retraction. It's just one long piece of filament. On more complicated prints the extruder needs to stop the filament and move to another location then restart the filament flow. It's this starting and stopping that will expose a bad extruder.

I created a test print where the filament needs to stop and start on each layer as the printer moves from cylinder to cylinder. As you can see from the print below, retraction is not working.

After tuning, the below print was the best I could achieve. You need to keep in mind this print is a tough retraction test since it is only a single layer thick. Any retractions issues are going to be magnified as there is no other perimeters being printed to help had the bad retraction attempts.

Just to show you what good retraction looks like check out the photo below.

Part of the problem (I feel) is the Bowden tube used to drive the filament from the extruder to the hot-end. A Bowden tube works similar to the way the break lines work on your bicycle. You push or pull a thin wire through the tube thus moving a small rubber pad against the tire rim. In this case we are using the extruder to drive the filament through a thin tube that is also connected to the hot-end. Since the tube cant match the filament exactly it needs a little play to compensate for variances in the filament thicknesses. This results in lag. Lag is the time that the extruder stops and the filament stops flowing. We retract the filament a small amount to keep it from oozing. The problem with a Bowden tube is that the retraction has lag as well. The longer the tube the more lag.

The Bowden tube is not the only culprit here. The over complicated extruder has too many moving parts. This provides more failure points. In addition, the gear train, while supplying more torque slows down the extruders ability to react to direction change.

I contact SeeMeCNC and was advised to try the following:

  • Try increasing acceleration: I did this
  • Try increasing current to the extruder motor: I did this
  • Try using KSSlicer instead of slic3r: I did this
  • Try using Reperier Firmware on the controller board: I did this

The Next Step

With the testing I have done, I was fairly certain 90% of my problem was the extruder. You have to keep in mind I am not alone in the problems I have been having. Others on the SeeMeCNC forums are having the same problems. One of the suggestions is to replace the extruder/Bowden/hot-end with a direct drive extruder mounted on the delta base.

I have had experience with several extruders:

  • MakerGear Extruder
  • Solidoodle Extruder
  • Afinia Extruder
  • QUBD Single Extruder
  • QUBD Dual Extruder
  • PrntrBot Extruder
  • MK7 Extruder

While all the above printers have advantages and disadvantages, I have found that the ones that work the best are direct drive extruders.

I own three QUBD extruders and decided to try a test with one mounted on the Rostock Max effector plate.

First Things First

The QUBD extruder is not without some issues of its own. These will need to be addressed before its installed on the Rostock Max.

QUBD Modification

Before mounting the QUBD extruder some changes need to be made to its design.

qubd modified.jpg

In order to test the new extruder on the Rostock Max, I created the temporary mount shown below.

extrudermount1.jpg

Here is the first print I made with the extruder after calibrating the filament for the QUBD extruder.

Once the testing was complete I created a permanent mount (below) that housed an extra fan to cool the motor. Later I will add one more fan that will help cool the extruded part.

extrudermount2.jpg

This is the first print after adding the new mount to the Rostock Max.

This is a high resolution print done at .1mm layer height.

As a comparison, the following two prints were done with the original extruder and the new one:

Was the new extruder a hit? A definite yes. There are a couple down sides however.

  • You loose about 2.5" of print height
  • If you print too fast the added weight will cause the plastic effector arms to wiggle, which can hurt print quality.

Heated Bed

The next problem area that needs to be fixed is the heated platform on the Rostock Max. It has two issues. The first is that it warps as the temperature changes, This can really mess up prints since when it warps the bed height is not consistent. The other problem area is the temperature of the bed will not go over 75c. For large ABS prints I like to set my bed to 95c - 110c.

After doing some research it look like the only solution is to add a second power supply. This supply must be in the range of 15-24v in order to get the heat up in the 100c range.

Important!!

Beware of 12V adjustable power supplies you get off Amazon or Ebay. I was lucky in that the one I purchased could be adjusted to 15V. I have purchased others and they were lucky to reach 12V with adjustment set to the maximum. The problem is that the cheaper units are often rejects from batches that would normally be sold to a reputable outlet. A 24V 20Amp power supply will run you about $80 from a company like Jameco. So keep in mind that a $21 unit is likely to be junk.

You will need to wire the power supply into your Rambo's heated bed input. I used 14Ga wire as shown below.

On the back of the power supply is a small adjustment potentiometer (below). Adjust the potentiometer fully clockwise then check check the voltage to make sure it is in the 15-24 range.

The downside to this second power-supply is that it needs to be be unplugged to remove power. As an option you could use a 12v relay connected to the original Rostock power supply to connect this own to 110v.

Homing Switches

The problem with the homing switches is that the striker ( a large machine screw) is not aligned with the lever switches you are instructed to install. You have to insert the screw at an angle (shown below) to get it to hit the switch properly. To compound the problem, if you drive the screw into the switch it can change the switches position, thus throwing your table calibration off.

home2.jpg

To fix the problem I created a laser cut mount for the machine screw. It positions the machine screw directly under the switch. In addition I changed the switches out for roller ball switches. The roller ball switches are a little more consistent than the standard lever switches.

I know that the Rambo supports optical switches. With this new design, the machine screw will be able to activate the optical switch.

One More Time

I was contacted by SeeMeCNC and given some new retraction settings for the original Rostock Max extruder. I removed my QUBD extruder and reinstalled the Steves-Extruder. I made several attempts but just could not get a good print. It all ended when the Hot-End jammed and the extruder started spitting out filament from the sides, as shown below. I took this as an omen. The Steves-Extruder has now been moved to my spare parts bin.

rat1.jpg

Something else I feel I need to point out. After using my modified QUBD extruder I came to appreciate the shape of its nozzle. The problem with the Rostock Max hot-end is that it is somewhat flat and tends to pickup any plastic that gets in its path. This cause many prints to fail that would otherwise be recoverable after the second or third layer is put down.

Build Plate

My Rostock Max shipped with an acrylic build platform. It warped the first time I used it. I wanted to do some testing with PLS so I had to find a better build surface. I tried printing on some plate glass but the PLA had trouble sticking. While shopping at WalMart I saw a pack of 6, 12" x 12" mirrored wall tiles. I decided to give them a try. I attached one using eight medium binder clamps, shown below.

My PLA was extruded at 190c. The bed was set to 70c. The PLA stuck to the mirror like glue. The Mr Shark print below was my best ever PLA print of any of my 3D printers to-date.

See the Mr Shark print in action.

The mirror was a great success for doing PLA prints. The down side is that the heated printed circuit board warps too much when heated to ABS temps. I can print small 4" or 5" prints in the center but the bed is too warped for anything larger.

I'm going to disassemble the bed to make sure the MDF under the bed is not warped. I may look at replacing this with a piece of aluminum.

Final Thoughts on the Rostock Max

The Rostock Max is certainly a cool looking printer, but it needs some tender loving care to get up to par with many of the 3D printers that are currently on the market. Even after all the modification I have made there are still issues that crop up with this printer that need fixes.

  • Bearing covers get flats spots worn into them
  • Excessive belt wear
  • Inconsistent temperatures on the heated bed
  • Warped Bed

In addition I find that I have to keep adjusting the tension on the carriage bearings. This may be due to the cover material wearing out.

 


Update 6/2/2013 - New Extruder Available

SeeMeCNC has come out with a new extruder. Hopefully this one will fix the extrusion/retraction problems that plaque the current extruder. Once I get one installed and perform some tests I will post the results.

 

New Extruder Install

I installed the new extruder but had to come up with a way to run the stepper motor wires from the top platform down to the base. I added the large channel to the machine shown below. I got everything hooked up and ready to test. 

 

How Does it work?

I cant tell you. After searching the SeeMeCNC site and forums, I could not locate any documentation, files, or information to support the new extruder. This is par for the course for the SeeMeCNC site. I have decided to shelve the Rostock MAX as I spent magnitudes more time on this machine than any other machine I have tested. Yet, it still produces the worst prints of any machine I have ever used. Currently it is not operational.

At best this machine is not even BETA. It is clearly still under development, as are the documentation, firmware, and configuration files.

I wont be going back to this machine until there is a concise set of instructions in place with proper links to a pre-configured set of firmware and configuration files.

 

Update 6/3/2013 - No More Troubles

There will be no further updates on this machine. It has been sold to someone who is willing to put the time into the machine to get the new extruders working. I managed to get some of my investment back and they got a good deal so we are both happy.