Using an R2 to build a larger workhorse printer

It took me 2 months of 24/7 printing to print these parts on an R2. The electronics enclosures had to be printed on this machine when it was working because they are too large for the R2. I used PETG for stepper mounts for temperature and PLA everywhere else.

This is just an R2 on steroids. I used the Partsbuilt.com system board and purchased print head plastic, the print head aluminum plate and high quality LM6LUU bearing from them. The design forces everything to be square. The alignment was within 1/2 mm after assembly and then tweaked to perfect.

I used oversize bearings on the 8mm shafts, I used a 30mm gear driving a 60mm gear on the x.y shafts. I did this for the 2 to 1 gain in torque and resolution and to reduce the needed belt tension. I used DVR8825 drivers on the steppers and set them to 32 micro steps which in conjunction with the 2 to 1 gear down gives me 4 times the resolution of the R2. The head runs unbelievably quiet. I use four 12mm posts for the 12" bed and dual Z motors. The Z motor mounts have fine adjustment screws to ensure that the shafts run dead true.

My goal was to make a 24/7 printing workhorse that is not as fragile as my R2's are.

If anyone has interest I will post all of the STL's and assembly pictures.

 

It is a lot of work to generate all of the documentation.. I will post if someone is interested in building it, otherwise it is a waste of my time. I stopped posting on thingiverse. The feel of thingiverse has changed.

 

This is an amazing project! I was thinking of doing something similar but I just don't have the time to take this on to do it from scratch. So yeah if you are ok with putting up some documentation (especially electronics if you changed the motors). That would be fantastic!

 

I will start the documentation in the next few days. It takes months to print all of the parts and the larger parts holding the electronics have to be printed on the larger machine. It is well worth your time as the resulting printer (which thinks it's just a larger Robo R2) is a work horse. I designed it to just keep on going, The design is completely self aligning and more rigid than you can imagine. It uses Robo R2 parts, the print heads are interchangeable. My preferred mods to the print head make it robust and the is nothing to break.

 

This is awesome! Super excited! I have a question, I see you are using a v6 heatsink. Did you have to file down either the bracket or the grove on the hotend? I did to get mine to fit.

 

search for
Making the perfect E3D Hotend

 

I am sorry, I should have read better

 

Here is the link to all of the files I used to print the parts. There is probably some old/junk files but I included the Inventor design files so that you can modify what you like. When I get some time I will expand further but this gives an idea as to the magnitude of the project.

For motor mounting parts I used Dikale clear PETG for temperature for all others I used GST3D which is the strongest PLA that I have found. I like using clear because it hides all of the flaws.

This is the Dual gear extruder I use. A huge improvement over the Robo arm.
http://community.robo3d.com/index.p...ith-dual-hotend-capability.24146/#post-141474

https://drive.google.com/drive/folders/1x5oWtXf_FsKVe1Uvi8KnDS9FbZrBgiyZ?usp=sharing

 

This is awesome! Thank you!

 

I have figured out a way to change the pint head from two 6 mm rods to one 8 mm rod and one 6 mm rod. An 8 mm rod is 3.17 times stiffer than a 6 mm rod. I have printed out the parts and will upgrade my large Robo clone in the next week. I see an advantage to using just one 8 mm rod, there is no problem with the alignment of two parallel rods. As I get higher quality bearings the tolerances get insanely tight for the plastic. The single 8 mm rod would be 1.5 stiffer than two 6 mm rods and it uses an LM8LUU bearing which is 45 mm long vs the 35 mm long LM6LUU bearing in the current print head. I got Fushi LM8LUU bearings from Amazon and they are ultra smooth and tight. I used a 3 mm OD brass rod with a 2 mm ID to run the filament inside the plastic, It should have less wear.

 

I am printing now using only one 8 mm rod instead of two 6 mm rods.. The Fushi bearings are verrry smooth and tight. I am using graphite infused bearings in the bushing blocks. The graphite bearings were a stiff fit but I just began printing. The quality of the print improved significantly. The improvement was most visible on curved surfaces. I can not feel any play in the head. I will see if the graphite infused sleeve bearings require a break in. I started with my existing head dipping 0.05mm in the center of my 12x12 bed. Since the 8mm rods are 3.17 times stiffer than the 6mm rods the 8mm rods were only .0.01mm.of the dip. I would now expect a dip of 0.03mm. When my print is finished I will measure the dip and report.

I will be implementing this on my R2's. The print heads are similar and I will supply the STLs tor replacement bottom print head. plastic as well as my print head plastic with dual gear drive which I use on my Robos.

After 8 hours of printing the graphite impregnated sleeve bearings were still stiff. I used axle grease on the rods (which I use on my R2's) and the stiffness was gone and the head moved freely. I measured the center of my 12x12 plate and it was still 0.05 mm high. Measured by using a dial gauge mounted to the print head. I can not tell if is the bed or the carriage, so I will need to get a different plate for my bed..

 

Is this a typo, or are you actually using a single 8mm rod for one axis and a single 6mm rod for the other axis?

 

I was not clear, I allowed a 6mm and an 8mm rod on each axis. I chose to only use the 8mm rod for a single 8mm rod on each axis. I am printing out the parts now for a print head that will allow the current Robo top to use the same. I will start a thread. I have not modified the current Robo bearing block holders for the 8/6mm. I should be able to do this within a week then anyone can have the single 8mm rod or and 8 and 6mm rod on each axis.

Attached is a picture of my Robo clone and print head printing the parts to allow the standard Robo Print head top piece. I have modified the Robo print head to allow an aluminum dual gear drive. This is a major improvement in the print head and I posted how to make it.

 

I bought my R2's for production work. The system board 12v power supply will fail if run continuously so I went to the Partsbuilt system board which is much more rugged with replaceable parts., Then the tiny bearings on the 8mm rods began to fail so I got high end bearings but even they will not stand up to 24/7 printing. If the 8mm rods are the slightest bit bent the bushing block holders will eventually break ( I did post a repair that seems to hold up). The connectors to the bed do not have a long life and I wound up soldering the wires directly to the bed. If you try and print PETG and raise the bed to an actual 80C the power connector will fail ( on both the R2 system board and the Partsbuilt board). If you are not in a temperature controlled area, and I am not, then you constantly have to adjust the offset as the plastic case expands and contracts. The existing feed arm lets the filament slip, so as the filament back pressure changes the feed rate changes ( i posted some spreadsheets on this)

So I built my own machine with large bearings and a metal frame which has corner pieces that snap into the grooves in the EU3030 extrusions forcing the printer to be absolutely square. The Partsbuilt board has a separate 24v wired input so the power connector fail is gone. With 4 posts and two z steppers the bed is rock solid to the frame and very repeatable. I made the x,y stepper driver directly drive the 8mm rods so there was no axial load, so the bearing load was very much reduced. I went to DVR8825 drivers with 32 micro steps instead of the original 16 and the machine is quite. I added a separate driver board for the bed so that the regulation on temp is amazing. It runs the R2 software which I have modded ( I have posted how to do it) I use a 6 x6 linear grid on the z height auto level and put in a 10 layer fade from the surface. I generated three tables for temp that take into account the type of surface used and will give an accurate temperature on the bed printing surface ( I calibrated with a thermal gun) In the firmware I modified the smoothing filer so that the bed and the hotend use different smoothing constants and get better regulation. Instead of two 6mm rods I use one 8mm rod on each axis with a 45mm long bearing. I get no play and reduced noise. The plastic arm on the filament feed was problematic so I changed it to a dual gear aluminum arm which has much better feed characteristic's ( posted it somewhere on the board). I then used a brass tube to carry the filament down to the print head for long life. The sleeve bearings on the 8mm rods are graphite infused so that I do not constantly have to lubricate them. I use 4mm id propylene feed tube, since the tube is just a guide I do not want a wavy filament to get jammed in the tube and stop the print,

This was not inexpensive and the parts took 3 months to print. I only see it useful for production work. All of the firmware changes have been posted along with explanations of how to do it yourself, it is remarkably simple. I will supply any/all documentation to anyone who wants it for anything above.