SMJ1

The Real Story of SMJ1

The Snapmaker J1 is not a perfect IDEX 3D printer, but it is a very good one. That’s my personal opinion.

Online and FaceBook user forums are available and have a lot of interesting threads (stories) of user experience. But forums are not a good place to seek service or repairs when something goes wrong. Highly experienced people like myself soon tire of the rhetoric and misunderstanding of the hardware functions, and limited understanding is clearly displayed in most non-qualified user postings.

Cries for help and defective answers are provided by the less than qualified.

I have attempted to be the “light in the dark” and have offered (posted) good advice and solutions. But that sound advice soon gets lost in the morass of the misguided responses. 

Many posters just want to present and see themselves in print and believe they are the pundit “influencers” of the forum.

I don’t feel that kind of influencing is my duty. Just because I own a (now) well functioning J1 doesn’t make me a pundit. It is the manufacturer who has something to gain that should be the pro active element in the forums with truly accurate response to issues large and small. 

My big Issues

The most serious Issue for me was a failed ribbon cable leading to the left extruder. The cable had a 90 degree crease near the extruder which became a single flex point when the head was moving. After 20+ hours of printing, the cable began to fail causing all kinds of intermittent issues that at first looked like nozzle plugging. Eventually the conductors in the cable totally became open (broken).

Factory support (not the forum) agreed and sent me a replacement cable. Much disassembly and assembly to install, but it solved the problem. 

The cause is a weak design in ribbon cable mounting and cable holding at the print head. A couple of added flexible shims fixed the defect and I shared the “fix” in the forum. But my “fix” has been lost is a sea of forum mis-information. Not my job anymore…

A second issue was an extruder filament feed missing steps when printing. It causes a thumping noise and filament ceases to flow. It is a high visibility issue in the forum and all blame (in the forum) has been placed on the extruder hardware. I recently saw one huge report (nicely presented in detail) how to totally machine out the extruder hot end and rebuild with special tubes. Far beyond the ability of normal printer users. 

For me the extruder is not the problem at all. In the slicer software default settings, there is a huge default filament retraction variable executed when parking the nozzle. In CURA it was 20mm. 

That 20mm retraction IS NOT NECESSARY with J1 IDEX design where the nozzles “park” on a rubber plug and can’t ooze.  Standard retraction (1.5mm) or ZERO retraction should be the default.

NOTE: This is NOT normal print retraction. It is a totally separate setting not related to the extrusion process when printing. It is a long retraction used when changing extruders to prevent nozzle ooze when not in use.

Set my parking retraction to 1.5 mm and all nozzle plugging problems have ceased, now over hundreds of hours of printing. A simple one entry software setting solves the major nozzle plugging problem. Of course my posting of that solution has become lost in the misinformation sewer of the forum. So again, why bother… I have decided. Just let them rant and rage and make poor decisions and post off-base solutions.

More Headroom

The last issue (for me) has not caused printing quality problems but is an unfortunate design issue. Printing with the top plate in place restricts the filament feed guides. The feed tubes bind against the top plate and side rails causing ugly noises when printing. The J1 case designers should never have restricted free movement of the feed system. Raising the top lid about 4 cm will prevent this issue. The top on is only needed when desiring to print high temp filament and a need to raise the printing environment temperature.

I printed a published Plastic top extender kit (set of parts) to raise the top when printing ASA or ABS

Other Crazies

Part of the “hobby” is modifying the hardware. Some fan(atics) believe the bigger the print cooling fan the better the print. Totally mis-guided. The stock fans on the J1 are totally adequate for the job. For PLA I run mine at 50% speed. For high temp filaments the fan is off. Bigger is definitely not better or required. It just adds weight to a moving component that should be as light weight as possible.

Other accessories (inside-case filament spools) and outside spool rollers are OK if you just want to “trick out” your printer.  IMHO they are not necessary if your hobby is printing, rather than “MODing” your hardware.

Speed

Unfortunately Snapmaker markets the J1 as a “High Speed” IDEX FDM printer. To perform that mission, acceleration and movement speeds have been set to extremes as defaults in the slicer software. 

Yes, the hardware is capable… for a while.  But all moving parts are slamming around and the entire printer case is rocking and shaking with a serious case of the “shivers.” This does NOT produce quality prints and can induce stepper overloads (stalls) and resulting shifted prints. 

Rapid start/stop, Bang, bang operation is never the best method for long equipment life and quality print results.

The pure truth is FDM plastic filament extrusion is inherently NOT a high speed process. There are laws of inertia and material flow and thermal transfer not manageable with hobbyist grade (affordable) hardware.

The software has become more complex and faster, and the number of available variables the user must understand and set has greatly increased. It’s no easy task, especially for the novice operator.

The J1 can and does run reliably in the 100 to 150 mm/s (average) range with normal acceleration and deceleration. Far faster than the original 40mm/s speeds of first generation printers and 60-70mm/s of later hardware.

I do not recommend J1 operation at 200-300mm/s with extreme acceleration/deceleration. That expectation, created by Snapmaker Marketing, is a flawed program in a market where published speeds sells product. Quality and reliability be damned.

IMHO hobbyist 3D printing is about design and tangible results. Not a drag race of printer speed.

A Business?

Folks using Hobby class FDM printers for “business” are delusional. At least for a serious real business where the only product is the FDM print. Buying a J1 to increase production because it is advertised as “fast” is going to bite you in the ass. Period.

FDM is a good process that can be used for a very small business start-up and hobby low income business. If you have found a large niche market for raw FDM prints, good for you. But no one is going to beat a path to your door just because you own a fast printer.

Ones business ability as a designer is far more valuable than the printed item. Sell your design skill, not plastic Junque.

All FDM prints are “cheap” layered plastic of little value and little enduring strength. Don’t kid yourself. Carbon fiber FDM isn’t what you think it is. Not equal to resin embedded long fiber carbon mat. Don’t bet life/safety on printed CF plastic parts.

What I have seen is FDM volume printing used where a low volume production doesn’t justify injection molding. Usually very low strength and decorative cases and covers. Many hobby class printer makers use FDM for printer parts because it is their business. 

Designers can be successful with hobby class machines for proof of concept and display models. But the business profit is not producing the model. It’s a step in a profitable process and is a means to an end, for something far more rewarding.

I sell some of my printed plastic designs. The printing is my “means to the end.” 3D printing displays my design and makes it interesting. My favorite term for this is Junque. A “classy” way of spelling junk.

I had a little laugh when in a forum, a post asked for a source for the J1 ribbon cable so the requester could have “spares” on hand. He stated he couldn’t afford the “down time” in his “business” waiting for a repair part from Snapmaker. He must have found one of those important niche markets! Good for him…

Not my concern, really. 

If your goal is the large mansion on the hill and chaffered limousine, then Hobby class FDM printing is not going to get you there.  Jest sayin’

Certainly not my goal. Good luck if it is yours.

Summary

Snapmaker J1 with good ribbon cables, proper parking retract setting and reasonable 100-150mm/s printing is a very nice enclosed IDEX printing system. Top raising not necessary but is an improvement for closed case printing.

I have used Snapmaker Luban slicer, Ultimaker Cura slicer, and wrote my own scripts for Simplify 3D (S3D). I like S3D slicer the best. Not a recommendation, but with J1, it works for me.


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