I was one of the first people in the US to get an FLSun SuperRacer. At the time I was using an FLSun QQS-Pro printer with fairly good success, and prior to that was my first 3D printer, an Atom2. When I saw the specs for the SuperRacer I realized it had components that resolved all the deficiencies I had learned about from my prior experience: The SuperRacer had a 24V power supply, so it had all the power needed to drive the stepper motors, fans, heater, and user input screen. It had linear rails and wider than usual belts, so end effector motion would be more precise. It had a color touch LCD screen to facilitate input, and it had optical end stop sensors instead of mechanical ones. Finally, it had a slightly larger print volume than either of my previous printers, and this was appealing to me because I typically print fairly large items. And it had all of this at a price that was literally $1000 less than my first printer. So how could I go wrong?

My initial results with the SuperRacer were quite good, but I soon realized there were some modifications that I wanted to make that would enable it to function better for me. This blog page explains what those modifications have been and gives some information about how and why I made them. I’ve listed the modifications roughly chronological order order, but some of them overlapped and/or got re-done as the result of prior modifications or problems I encountered.

Capricorn Tubing

I substituted Capricorn tubing for the PTFE tubing that came with the printer when I first assembled it. I had switched to Capricorn years earlier as a means of reducing stringing, and it definitely helped with that. The reason is that the internal diameter of Capricorn is slightly smaller than regular PTFE, so there is a reduction in the amount of twisting that the filament makes during retractions.

Fan Ducts

The SuperRacer stock fan ducts have a fairly crude shape, and several people were quick to design and print new designs that had better airflow. Now there are quite a number of available designs, some of which are quite fancy indeed. These are the ones I use, but for more just do a search on Thingiverse for “SuperRacer”


Build Plate

Several years ago I found an add-on build plate that solved all the problems I had encountered with pint bed adhesion. The plate was slightly flexible, which made it easy to remove a print by flexing the plate after the print was complete. Subsequent to that I found an even better option called a Flexi-Plate. This one is much more flexible so it is even easier to remove finished prints. Unfortunately neither of these items is still available, but here is a photo of the first one in operation:

Well used but still very effective

Power Supply

As noted above, the SuperRacer came with a 24V power supply. I quickly learned the power supply’s fan was the loudest thing in the printer. The fan started as soon as the power was turned on, and it stayed on as long as the printer was powered up. I knew there were power supplies with fans that turned on only when they got hot enough to need the extra ventilation, and based on what I read online some of the best power supplies were made by Meanwell. I found the following unit at Amazon and bought it:


There is good news and bad news about this power supply. The good news is it’s fan doesn’t turn on until it is needed – typically about 10 minutes into a print. The bad news is that once it turns on it doesn’t turn off until the print is finished. And it is only a bit quieter than the stock fan. Nevertheless, if you want to try it here’s a blog page about how to make the swap:


Extruder #1

The stock extruder supplied with the printer was a BMG clone. Regrettably the clone extruder was poorly made: the internal tolerances were not great, the gears and bearings were not of high quality, and the extruder was missing an important internal part that guided the filament into the gear train.

The net result of this was many people complaining about and replacing the extruder with a different/better one. I found many online postings that lauded the capability of the BMG extruder, but those cost about $95 – which was close to 1/4 the cost of the entire printer. So I opted for a BMG clone that I got from Amazon for $39.95. This is it:


Installing the extruder was simple – it was literally a drop-in replacement for the stock extruder. Switching to this one solved all the problems I (and many others) had been having with the the stock extruder. I suspect the clone was actually made by BMG because one of it’s internal parts had the letters BMG stamped on it.

Replacement hotend: nozzle, heat break, heat block

It wasn’t very long before I noticed some leaking melted filament around the SuperRacer’s nozzle. In addition the surface quality of my prints was not what I thought it should be. I was also getting some nozzle clogs which were more of an annoyance than anything else – I had learned before that the easiest way to clear a clogged nozzle was to simply remove it, torch it, and then reinstall it. This blog page explains how to do that:


Unfortunately, after clearing the nozzle I was still getting less than desirable surface finishes. So I decided to change the key hotend parts (nozzle, heat break, and heat block) to more common/standard ones. These are the parts I bought:




Assembling these parts is simply a matter of screwing the nozzle and the heat break into the heat block and making sure there is a tight fit between the 2. Then it is a simple matter to insert the heater and thermistor into the heat block and tighten their screws just tight enough to hold them in place. After that the complete assembly is inserted into the aluminum heat exchanger and secured there with 2 set screws. Here are 2 photos that show how it all looks:

I thought it would be a simple matter to mount the new parts onto the end effector plate, but that was not the case. I discovered that the new heat block was slightly wider (by just a millimeter or 2) than the stock one, and consequently it would not fit through the oval shaped opening in the end effector plate. So I had to use a Dremel tool grinding wheel to enlarge the narrow part of the opening a small amount. That enabled me to get the complete hotend assembled and working OK.

It may be that in newer printers FLSun has changed the shape of the end effector plate so it will accommodate the larger heat block – I did see one post from someone who made the same change and didn’t have to alter the shape of the opening.

Extruder #2 & Filament Runout Bracket

I ran with the BMG clone extruder for quite a while and had no significant problems with it. But in the back of my mind I always had the desire to change from a Bowden tube configuration to a direct drive extruder. The truth is the Bowden tube concept was a simple and easy way to get filament to the printer’s end effector. Originally delta style machines were created to do precise “pick and place” operations with small mechanical parts; there was no filament involved. Delta style 3D printers happened after Cartesian printers were well established, but the delta end effector mechanism was not strong enough to maneuver the extra weight of an extruder mechanism. So the extruder was stuck on the printer frame and a Bowden tube used to get the filament to the hotend.

Recently something happened with stepper motor design that allowed a much smaller and lighter motor to have the same turning power as a much larger one. A couple of new extruders were released that used these smaller motors, and I read about some people who had adapted them for delta printers. After looking at what was available I opted to get the BMG LGX-Lite extruder. I ordered it from the manufacturer in Sweden and got one of the first 50 that became available. Now they are easier to get – just do a search for LGX-Lite and you should find several sources.

Installing the LGX-Lite was fairly straightforward. I wrote this blog page describing how I made the transition:


After everything worked I simply removed the old extruder and PTFE tube from the printer. But that left several inches of unnecessary length on the SR’s stock bracket that holds the runout sensor and extruder. This was disturbing and I found a posting that had a short 3D printable bracket. I don’t think the STL file for this bracket is posted online, so here it is:


This is how it looks on my printer:

Marlin & TFT70 Color Touch Screen

After I swapped out my original Atom2 for an FLSun QQS-Pro I thought I’d try upgrading the Atom2 from 8-bit Marlin 1.x to 32-bit Marlin 2.x running on a 32-bit motherboard, a 24V power supply, a better Z-Min sensor, a better screen, and better (quieter) stepper motor drivers. (The QQ-S Pro had most of these features, which is why I bought it.) I got all the hardware changes made OK but was never able to get the Marlin firmware working properly. I finally gave up – which is not normal behavior for me. But I learned some valuable lessons.

Most importantly I learned that Marlin is a particularly complex piece of software. It is comprised of hundreds of separate modules, and these modules cross-communicate using variable names that are sometimes very descriptive, but sometimes very similar and/or confusing. Furthermore, the module’s code is, like all code, subject to failure if just a single character is out of place or incorrect. Here’s a typical example of Marlin code:

//Type of Driver TFT Color (1 choice)
#ifdef TFT_DWIN_UI
  #define DGUS_LCD_UI_MKS           //Mks_H43_v1.0 (T5LCFG_800x480)
//Note for QQSP/Q5 DGUS/DWIN: The wiring is done on the UART2 (Wifi socket pins(PA10/PA9) for Tx/Rx).
  //#define DWIN_CREALITY_TOUCHLCD  // CREALITY/SuperRacer (T5LCFG_480x272)
  //#define DWIN_MARLINUI_PORTRAIT  // A DWIN display with Rotary Encoder (Ender-3 v2 OEM display).
  //#define LCD_SERIAL_PORT 1
  #define TFT_INTERFACE_FSMC        //Default socket on MKS_nano, mini, hispeed.
  #define TFT_RES_320x240
  #define MKS_ROBIN_TFT32           // (Default) Mks_Robin_TFT_V2.0
  //#define MKS_TS35_V2_0           // Only for NanoV2 or V3
  //#define MKS_ROBIN_TFT35         // Mks_Robin_TFT35V2.0
  //#define MKS_ROBIN_TFT43         // Mks_Robin_TFT43 
  #define TOUCH_SCREEN              // (C/F) (Default) UI MARLIN

To deal with Marlin you have to install a compiler, the most common of which is Microsoft’s VSCode. It’s a free install, but it is fairly complex itself because it is targeted at anyone who uses most any programming language to write code for Windows . Fortunately I’ve used other Micorosft compilers, so it wasn’t much of a hassle for me.

Since the SuperRacer already had most all of the hardware enhancements I wanted, my primary reason for switching to Marlin was to make use of the TFT70 screen I had bought for the Atom2. That screen is just terrific actually – it’s big and it gives you access to all sorts of firmware variables you can normally tweak only by changing Marlin code and recompiling it. I thought simply replacing the stock SuperRacer screen with the TFT70 would be easy to do. This was not the case.

The reason is that the motherboard shipped with the first batch of SuperRacers was a modified clone of the standard BTT SQR motherboard. I had got one of these running in the Atom2 along with the TFT70, so felt fairly confident I’d be able to get the screen running OK on the SuperRacer.

But I was unable to do that due to the modifications FLSun made to the stock motherboard design. For their screen they added an extra connector on the motherboard and wrote a custom module to drive the stock screen. The TFT70 could not use that new connector, and the custom module made it impossible for the motherboard to communicate with the TFT70. I tried all sorts of things to get the 2 to talk to each other, but I was never able to get anything to work.

Fortunately there are 2 people on the Facebook SuperRacer forum who were able to make it work. They are Foxies and Cyril Guislan. I don’t know how they did it, but they got Marlin, the SuperRacer, and TFT70 to work together. And even more spectacular, they did it for whatever motherboard the SuperRacer might have. Interestingly, they each used a different method for doing this. For detailed reasons I’ll not go in to here it turned out that Foxies’ method worked for me. In fact, the code I showed above is his code. Note the mention of SuperRacer and the 4 types of motherboards it might have.

So the bottom line for Marlin is that it is a very challenging beast to deal with, but it can be tamed if you get the right kind of help from someone who knows what they’re doing. My sincere thanks to Fox les for all the help he gave me.

Now – about the TFT70. It is a very popular screen and there is tons of information about it online. Here’s the link to the BTT page for it:


To use the TFT70 you have to attach it to the printer of course. That means you need a case for the screen, and a way to attach that. Here is the link to the TFT70’s 2-part case I came up with – it does not require any hardware or modifications to the printer:


To attach it I used hot glue on the bottoms of the horizontal tabs. That allows you to carefully remove the printer’s top cover – after detaching the 3 cables from the screen. Here’s a pic of my setup (before I got the new reel holder):

There’s a different view showing the back at the bottom of this page. Using the TFT70 is just like using 2 monitors on your PC – once you try it you can never go back to the old way.

Tool Holder

I’ve had a large tool holder attached to the front of whatever printer I’ve had for quite a while. Unfortunately that tool holder got displaces by the TFT70 screen, so I had to find an alternate way to attach one. Someone made a bracket that fit on the SuperRacer’s vertical columns, so I tweaked that by adding slots for the tools I most commonly use on the printer. Here’s the link for it, including some tips for installation:


Spool Holder

Because most of my prints run for many hours I got tired of dealing with regular sized spools of filament. SO I searched for and found a supplier of large spools – 2.5 or 5.0 kg. % was really huge so I decided on the 2.t5 kg size and have been using that for more than a year.

The problem with spools that size is they don’t fit on any standard spool holder. Initially I found a pair of roller bearing supports that fit under each side of the reel, but these tended to move around on the top of the printer, and I had a couple of times when, for some unknown reason, the spool fell off the rollers. That was not nice. So I got online and finally found this holder that works really well:


This puppy is very robust and fairly heavy. Here’s a photo of it in operation – note that I had to cut 2 wooden skis for it to sit on:

I haven’t decided if I should hot glue the skis to the top of the printer, or to the bottom of the reel holder’s rubber feet (or both!) It seems to be fine as is, so I’ll likely leave it like that.

21 Jan 2021