Print Speeds

There is a marketing war with 3D FDM printer makers of who can advertise the fastest printing machine.  Within the last year, the brag print speed has moved from 100 mm/s, to 300mm/s, and now to 600 mm/s.

Acceleration has leaped from 1,000 mm/s^2 to 20,000 mm/s^2

There are practical and physical limits on how fast hot melted plastic can flow from a pin-hole size orifice and be deposited in multi-layer, super thin layers. At the same time producing the highest quality practical printed item.

Speed, Quality, Low Price. Pick any two. 

So, what the marketing folks are bragging up, is the highest peak speed at which their hardware can reach while depositing a layer of plastic. Not the continuous sustained real-world, small, complex shaped item, printing speed. Where direction changes are often 90 degree corners and straight paths are short.

Very few 3D printed items are produced with single wall vase-mode at 0.10mm layer height with very broad and smooth direction change, where 600mm/s can actually be sustained for short periods.

Travel speed is a different kind of movement without flow of plastic. Used to change print head position. Travel is almost always done faster than printing. But it doesn’t have to be faster.

Advertising the travel speed as improved print speed would be deliberate false statement. I don’t remember ever seeing that. No issue.

The benefit of this race for speed bragging rights, is the faster machines ARE generally better quality. They are excellent printing machines when run at the reduced speeds compatible within the filament flow characteristics that the Filament Makers recommend. 

I see a few new “designed-for” high print speed filaments are becoming available. This proper made-for-high-speed material will become more available as the machines improve.

Mechanical vibration due to inertial speed and direction changes is being compensated through software artificial intelligence. But that simply avoids acceleration and speed in ranges where harmonic vibration occurs. It cannot change the Newtonian laws of motion. 

Machinists learned long ago the best reduction of vibration is machine mass. Moving parts need to be as light as possible and the machine frame needs to be as heavy and non-flexing as possible. Bolted to foundations penetrating into the mass of the earth.

A 30 pound plastic and tin box setting on a wobbly bench is never going to be a high quality high speed 3D printer. A 500 pound  cast iron machine bolted to a concrete slab floor is a great starting point. I exaggerate like the marketers, to make a point.

Sudden, high speed starts and stops are very hard on belts and bearings, imposing load g-forces very much higher than gravity weight. Wear and stretch rates will be higher than at low speeds. In other words, the machine will be “working” much harder per unit of time.

Think of it another way. If a machine can make 1000 parts before failure and is run at 10 parts per hour. It will work for 100 hours. Same machine making 50 parts per hour would run for only 20 hours.

I am not comfortable listening to my pricy printer making “bang-bang” sounds with slamming starting, stopping, and reversing movements. I am not so concerned about high speed movement friction wear as much as the near instant (3 micro second) full speed high-g direction change.

Acceleration variables are intended to ease into and out of direction changes to reduce sudden g-loads on mechanical parts. In the lust for speed, this desirable function is being severely reduced.

I am not involved in a production manufacturing business where time is money, and where faster means better cash flow.

For me, constant high speed printing that reduces print quality and/or increases machine wear and tear, is not a desirable way to operate my new high speed “capable” printer.

Speed does not come without added hardware cost. Consumer pricing is now in the $600- $1000 for enclosed, high speed capable machines. With all the bells and whistles they are in the $1200+ range.

Basic (slow) FDM printers are still available in the $150-$500 range. Big difference. It’s why I want to take good care of my investment. I have no need to operate my J1 in demolition derby mode to print a mediocre looking Benchy in 10 minutes.

Ándele arriba

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