The Snapmaker J1S has become my favorite, extremely reliable, go-to FDM 3D print system. It started life as a pre-order J1 and I added the case fan kit about 6 weeks ago. That makes it a J1S.

The machine was not without some faults at the beginning. 

The first major problem was the ribbon cable between the left print head and the rear of the machine. A severe 90 degree crease was created in the ribbon from what apparently looks like hitting the right extruder when traveling to the extreme right (and left) rear area of the build plate. 

Once the crease was created, it produced a concentrated flex point that soon (because of the flexing) broke the wire in the cable.

I received a replacement ribbon cable under warranty and my electrical issues were corrected. I took steps to make sure the failure point was protected by adding support material cut from the original ribbon cable.

I also avoid printing into both rear corners of the build plate.

Somewhat of a design flaw is the amount of free space under the top plate of the printer for feed tube (NOT Bordon Tube) movement. I printed and added a 25mm riser edge all around the top. (There are print files available.) I also added little ramps on each side so the tubes can slide upwards when needed and not suddenly jump (making a KLUNK) to a higher position.

There was one additional issue with what appeared to be nozzle flow problems. It turns out there was (is) a setup error in CURA with the filament retraction when parking the heads. Default was set at 15mm of retraction. The correct amount is zero to (no more than) 1mm. THIS IS NOT THE SAME SETTING AS STANDARD PRINT RETRACTION. It is Head Parking retraction, a separate and somewhat hidden variable.

Huge fuss in the Snapmaker J1 forum about poor nozzle design. It is not a design flaw at all. It is a simple setting the proper value in the slicer software. End of problem.

I now do near perfect IDEX FDM printing with all materials and temperatures when I set all the other variables correctly, which is SOP (Standard Operating Procedure), When using the proper values with variables makes all the difference. 

There is an operational learning curve. Most newbies first blame the hardware rather than examine and fully understand the variables under their control responsibility. Published settings are starting points and are not perfect.

Last suggestion. I always use the plain glass side of the build plate with a light coating of hair spray. The labeled black print surface works with PLA, but is not always dependable. Print sticking not good? Use plain glass with adhesive such as hair spray. Which IMHO is the easiest.

I have discovered one other (new) slicer variable called “Monotonic Surface Order”. It causes a top or bottom surface to be printed all in one direction to improve symmetry of the surface. But when deployed when not really needed will cause excessive rapid and repeat travel moves from side to side to maintain symmetry when not really required. Use only when desired. This is a slicer issue. Nothing to do with printer design.

So, Yes! I am now very happy with the Snapmaker J1s. The big cooling fan is a good option for PLA prints. It’s my first enclosed FDM printer and an enclosure is a feature really valuable for higher temperature materials.

Currently a J1s about double the cost of a good quality mono-filament printer, but it is also double the printer. It’s the “old-saw saying”, two heads are better than one. I think A good IDEX is top of the dual head features list.

Best IDEX? I can not say that. But my J1S now does every print I desire and does them very well. Recommended,