Makerbot Replicator 2X: Review and Improvements

I’ve been a fan of 3D printing for years. A few years ago I bought my first 3D printer, the UP! printer from PP3DP.com (made by Delta Micro Factory in China). The UP! printer had gained a reputation for simplicity and easily achievable high quality prints. I was not disappointed at all with the UP! printer experience, though I will say I learned a lot by using it, becoming familiar with some of the difficulties associated with 3D printing such as platform adhesion and warping and problems extruding PLA.

Once I switched to printing on perfboard using the UP! printer, my platform adhesion problems mostly became a thing of the past. As long as I had the initial height set correctly and the platform was reasonably level, the raft stuck pretty reliably. I never went back to the various other solutions such as painters tape or platform adhesive. The UP! printer was now something I could very reliably print on especially if I stuck to ABS material and I had some success with PLA as well.

The time came when I wanted something a little fancier.  Something that could build a larger part and maybe handle certain materials a little better, like flexible filament. Maybe play around with dissolvable supports. I wish Delta Micro (Makers of UP! in China) would have come out with a larger printer with dual extruders, but sadly they haven’t yet. If they made a larger version of the UP! printer that worked as well, they would surely have a winner on their hands.

7_More8_2x_DualMakerbot 2X as shown on Makerbot.com

After much waiting and looking at what the market had to offer, I decided to get a Replicator 2X and give that a try. I had seen the Replicator 2 in the Microsoft store and it looked well made. The $400 off sale over the holidays pushed me over the edge. The Replicator 2 only does PLA material mainly due to its lack of a heated build platform, where the 2X mainly does ABS due to it’s lack of a filament cooling fan (an important feature especially for PLA materials). You can attempt to use both materials on either printer, with some drawbacks due to the differences. Aside from the heated build platform difference, the 2 only has 1 extruder and the 2X has 2 extruders.

After having worked with the 2X for awhile now, my basic take on it is that Makerbot saw an opportunity to ship a dual extruder version of the Rep 2 that would be good for ABS as well. So essentially what they did was start with the Rep 2 and remove the filament cooling fan from the carriage and add another extruder. The build platform was upgraded to be heated, and plexiglass covers were added to provide a better build environment for ABS.

This all sounds nice, but there are some gotchas. Cooling the filament a little in order to “freeze” it after it’s extruded is essential for portions of a print that have overhangs. The Replicator 2X has no fans for circulating air over the extruded filament, and as a result, print quality suffers substantially especially if there are overhangs, but also sometimes in areas with no overhangs. After adding the 2nd extruder to the carriage, there simply was no room for a filament cooling fan on the 2X, and this left users to come up with their own solutions.

Some larger “industrial” 3D printers that use the same FDM technology actually have a heated environment to reduce warping stresses as well as strong warm air circulation and disposable build trays (with very good adhesion) and even head cleaning brushes to provide reliable results. I have a Stratasys printer at work like this. It’s a monster and uses filament cartridges that cost about 5 – 6 times as much for the same qty of filament. It’s a little slow as well, but it does a great job. So we can look at what they have done in their design and operation that could improve the results low and mid level FDM machines can achieve.

After about 6 months of using the 2X, I can say that probably the 4 greatest things for improving the Replicator 2X experience are filament feeding, filament cooling, firmware, and slicing software (Makerware).

Filament feeding: There is little more frustrating than checking on your print an hour or so into a build and finding that your extruder has stopped feeding material, and that you are “air printing”. This is something that the extruders on the Replicator 2X have been very prone to. You’d think that the MK8 extruder, with the benefit of learning from previous extruder revisions and knowledge and experience gained by so many people over the last few years would result in a well designed extruder that would not be so prone to jamming. Even my older UP! printer pretty much never ever jammed using ABS (PLA was a different story though). Fortunately in the spirit of hacking, learning and sharing, several improvements have been floating around and are available on thingiverse or even on Amazon if you don’t want to make your own. I decided to go with this option which can be found on thingiverse. It has been working reliably so far:

http://www.thingiverse.com/thing:222667

Extruders_Assembled_preview_featured

Filament Cooling: Again, with all of the knowledge gained by the open source and 3D printer design community, you’d think that some type of filament cooling mechanism would have been included. It’s really necessary for creating prints you can be happy with. My UP! printer has a fan on it just for this purpose, and makes really crisp prints due in part to this feature. I think MBI just didn’t put much thought into this or decided that as part of the 2X being for more advanced users that people would just have to come up with their own implementation for this. Not really such a good thing for a printer costing in the mid $2000 range, especially when Wanhao “Duplicator 4” printers look to be nearly identical for half the cost. I’m not sure that they have a good filament cooling fan either but it looks to be basically the same machine for much much less. I decided to try this idea from thingiverse. It has worked well so far:

http://www.thingiverse.com/thing:228055

COOLING_FAN-3089_preview_featured

Firmware: Firmware plays an important role in the operation of such a machine, not just for basic tasks like storing machine offsets and loading & unloading filament. In the case of the 2X, the major issue seems to have to do with precise timing control for doing things like generating more accurate time bases for controlling the stepper motors as well as good acceleration/deceleration controls for the stepper motors. Stepper motors are the motors that move the carriage and feed the filament in the 2X and most low to mid range FDM printers. They are cheap and effective. Servo motors are used in more expensive 3D printers and CNC machines and offer “closed loop” control typically with more precision and speed and force.

It so happens that there is a firmware alternative called “Sailfish” which from what I gather shares a code base with the standard Makerbot firmware at least up to a point. It’s reported to be superior with regard to better written software to handle low level timing controls and better stepper motor acceleration. It also offers some features that the standard firmware does not offer such as build speed control and temperature control while the job is running. As an engineer myself who has written a fair amount of firmware including stepper motor controls, I can believe the benefit of better firmware. Many people may dismiss firmware as an insignificant component of print quality, claiming it’s really the slicer program that generates the toolpaths that matters. But it’s really both, and just the added features, let alone the low level control improvements, makes it worth upgrading. Many people have reported better results using Sailfish firmware, and I agree. I recommend going to the trouble of changing the firmware if you really want to get the most out of your printer. You may or may not see a lot of difference depending on the type of models you print. It’s not as important as the filament feeding or filament cooling upgrades though. Makerbot currently has instructions for loading the Sailfish firmware on various printers they make so that’s nice. Instructions for installing Sailfish firmware on the 2X can be found here (pay attention to specific model instructions):

http://www.makerbot.com/sailfish/install/

Slicing software: Replicator 2X machines use something called “Makerware” for it’s slicing. Slicing refers to taking your model and generating the toolpaths and codes (g-code) to make your part. This includes support structures and other things that help to build a part. While I am not that familiar with the history of Makerware, it seems that it’s the first non open source version of slicer software for Makerbot machines. Makerbot made a decision to get away from open source software. Prior to this, there was Replicator-G that can still be used if you like. One of my first tests with Makerware was to print an iPhone case “upside down” so that there was a hollow area underneath that would have to have support structures under it to build properly. Much to my surprise, Makerware did not generate support structures in the large area under the part, and the print came out horribly bad. This immediately crushed my confidence because IMHO, a middle of the road default setting for “good” quality should not have this kind of glaring oversight. I did find out later how to turn on supports under “bridges” with a custom profile. There are a whole lot of custom little tweaks you can make with a custom profile. It can make your head spin. Each one has a specific purpose. Contrast this to the UP! slicer (which is not open source) which would have printed the part very well with little effort. IMHO, the defaults in Makerware should do their best to deliver a good part. In my quest to find better software for slicing, I opted to buy “Simplify3D” for $140 because it has a lot of advanced features and acts a lot more like a real CAM/machine control program. Better control over supports and options for treating different regions of a model differently makes it a lot nicer to work with. The toolpaths look reminiscent of the UP! printer slicer in some regards. I use it for all of my single extruder builds but find it a little lacking with regard to support for good dual extruder builds mainly because of the lack of good purge/prime operations for the nozzles. Makerware offers the “purge wall” which is good for keeping the nozzles purged and primed between layers. Simplify 3D does have the ability to let you place your own custom g-code that can execute between layers or between tool changes. Some people have used this to implement a real nozzle wiping mechanism like the big machines do. I have it on my to-do list to add a nozzle cleaning brush to my machine and the necessary g-code. This should be superior to the purge wall that Makerware offers. IMHO, all dual extruder machines should have proper nozzle cleaning mechanisms rather than just rely on some makeshift solutions. Many people really don’t want to pay any money for a slicer. I understand that and agree that the slicer that comes with the printer should be adequate, but I also don’t mind buying something at a reasonable cost that works better and works for many different printers. Simplify3D can be found here:

http://www.simplify3d.com/

So in summary, I finally feel like I can half way trust the 2X to make decent prints with a fair amount of confidence, but at the price of having to tinker with it way more than I wanted to. I want to use my printer to make models that I design. That’s why I bought an UP! printer years ago because it had an “it just works” reputation. I still use it. I do not particularly want to have to improve a 3D printer to the point where I can start using it to produce models that I design. I don’t really want to spend time on that. For some people this is how they enjoy their 3D printer, by improving it so it works well. I would rather use it to just print great parts. I did learn a lot, and the 3D printer industry will no doubt keep growing and improving. To some degree I was spoiled by the UP! printer and the above experiences are all too common for other printers I think. It’s like one of those bad situations you have to work through. If you make it through, you come out a little wiser and better for the experience, unless you get so frustrated that you just give up and get soured on the whole technology. Your first experiences with a technology really impact you for a long time, especially negative ones. For this reason I would not recommend the 2X as a first printer despite its attractive sounding features. Nor would I recommend it to someone who does not want to fool with it a lot before getting good prints. However if you do get one, or have one already, I do think these few things will really enhance your experience and convert the 2X into a useful machine capable of doing some pretty nice prints. If you are considering whether to get a single or dual extruder machine, be aware that dual extruders, while offering the ability to do more exotic things, add complications like nozzle purging and priming when switching nozzles and nozzle leveling so that one nozzle does not collide with the model that the other nozzle created, potentially knocking your model loose from the platform. Dual extrusion sounds pretty sexy, but I don’t use it as often as I thought I would due in part to these reasons.

I hope you have found this interesting and of some use. If you have a friend who has a 2X, pass it along!


CNC machine improvements

I’ve really enjoyed this little CNC machine I bought earlier this year. It’s been a good learning experience and I’ve been able to make some things that I just couldn’t make using a 3D printer. CNC machines offer greater material choices and precision, but are also harder to use than 3D printers. It’s a whole different world compared to 3D printing.

I bought my machine for about $1200 (with shipping) off of ebay from a company in China. For that price I got a small 4 axis machine (3 axis plus rotary axis), ball screws for good precision, a controller box, and a couple of bits to get started. Hard to beat the price, and I expected some inadequacies in the product. I’ve been able to identify some not so good qualities in the machine and made improvements and enhancements which I’ll preview here.

Here’s a photo of the machine, post-enhancement. I’ve swapped out the spindle motor, leveled the table, and added a camera to allow me to make more precise parts. The camera is essential for lining up the work piece again after it has been moved, like when it’s flipped over to machine the back side. I also added a wireless MPG (manual pulse generator) for controlling the machine during setup and operation. That alone is a big improvement to the process and is well worth it.

improved-cnc-machineImproved CNC setup.

Naturally, the new spindle motor didn’t “just fit” onto the existing machine. It was off by a millimeter or so in motor diameter and also in a couple of the mounting holes. I chose to make a new mounting bracket for the motor using my 3D printer. The bracket is certainly not as strong as the machined aluminum one that came with the motor, but seems very adequate for this machine. Because of the larger size of the motor, I had to change the configuration a little for the motor mount, and I made a new cable chain on the 3D printer to route the wires for spindle motor power and USB camera connection. I added a new, dedicated bench power supply for the spindle motor which is a big improvement over the spindle motor speed control that came with the unit. Actually the spindle motor control that came with the unit as part of the controller was pretty cheesy and burned out twice. The motor wasn’t so good either, and sometimes made noise like the bearings were not very good, including a loud vibration in the motor whenever much of a lateral load was placed on it. It would squeal pretty loud.

It’s so much nicer to use this machine now. I’ve still got some learning to do and experience to gain. I’d hardly consider myself a machinist but at least I can make some things I didn’t have the means to make before by myself.

Here’s a picture of the machine in its original state.

basic-cnc

Original CNC machine configuration.

In upcoming articles I’ll provide a little more detail on these enhancements. Stay tuned!

CNC Vacuum Plate Pt 3

Today I’ll show the first test of the CNC vacuum plate, but first we’ve got a little bit of work left to do to make the top part. You may recall that I likened it to an air hockey table, but instead of forcing air out of the holes, we’ll draw air down through the holes with a vacuum pump.

Here’s my top plate being drilled with an array of holes. Again, remember that if you use extruded acrylic, you’re likely to have a lot of problems while machining or drilling it because the plastic melts and gets stuck on the bit and also leaves rough edges. Cast acrylic chips away nicely.

vacuum-top-plate

Drilling holes in the top acrylic plate.

The next step for me was to make an adapter to go from the vacuum hose to the cavity at the end of the base plate. I won’t go into a lot of detail here but what I did was make the adapter on the 3D printer because it was faster than machining one. 3D printed objects made with the FDM process (using a spool of plastic filament) are usually fairly porous (not airtight) so I’ll use some glue and/or tape to improve the seal and fill up the pores at least well enough for it to function.

3d-printed-adapter

Adapter being printed on a small 3D printer.

Finally, putting it all together, it’s looking pretty good!

finished-vacuum-plate

Finished assembly.

On the left you can see the hose adapter. My little air hockey table is sitting on top of the base plate. I’ve temporarily fastened the top to the base with a few spots of glue and tape around the edges for a seal. Later I’ll make a more permanent seal after seeing that it works ok.

vacuum-plate-test

First test. It works!

For the first test I’ve connected a pretty strong vacuum pump that’s designed for applying vacuum to air conditioning systems to remove all of the refrigerant, air, and moisture. I doubt this is necessary and I’ve seen others use shop-vacs. This was just convenient for me and gives me a chance to see how much leakage there is in my system. I know that with this pump I should be able to get over 29 inches of vacuum, but as you might be able to see, I’m only getting about 14 inches on this test, and sometimes as little as 7 or 8 inches. I’ve got some leaks, probably mostly in that area where the hose adapter sits. You can see I’ve taped over unused holes since the 6 x 6 inch board doesn’t cover the whole area. Imperfections (like board warping) in the pcb also contribute to leaks. As it turns out, 7 inches of vacuum seems to hold it pretty well. I had to apply a lot of force to move it by hand. It was stuck very well.

I hope you’ve enjoyed seeing this and it’s been a fun and useful project. Later on I’ll show some other improvements to the CNC machine itself and refinement of this fixture that allows greater precision when making circuit boards on a machine like this.