Reducing weight on Cartesian printer X and Y axis

I see many videos and discussions on reducing print head weight on the x axis either by lightweight hotend and extruder combo or bowden design to reduce ringing with increased speed

If the bed weight is generally more than the hotend how much impact does reducing the weight of the hotend have? How much of an impact does bed weight have on ringing or is that more of an issue related to the actual hot end swinging around and not the print surface.

If ringing is also an issue due to the weight of the bed are their designs that are aiming toward reducing bed weight? Like lightweight heatbed/print-surface/plate.
With the amount of mass on the bed I don't think I could decrease it's weight to be less than a modest hotend/extruder combo. But the bed could be driven by a bigger stepper, would a large stepper and a tight belt overcome any ringing that could be presented by the weight of the bed?


Would the alternative be to just use a core XY or delta design instead and deal with weight in one area.

... or set the (heavy) head as "base" and move the print bed with the printed part in XYZ

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Quote
VDX
... or set the (heavy) head as "base" and move the print bed with the printed part in XYZ

lol

You could make a printer with interchangeable beds of different sizes and use the bed that is just large enough to accommodate each print.
You can print on a sacrificial foam bed without a heater or metal plate.

If you were really concerned about ringing, you'd just print slowly. "Ringing" is a euphemism for printing fast. You're not really concerned about ringing. You really want to print fast, but ringing is spoiling your high speed prints.
If you want to print fast and avoid ringing, the best thing to do is reduce the moving mass and make everything as rigid as possible. That's why people build printers that don't attempt to throw a massive bed around at print speed.

It isn't hard to build a relatively light mechanism that can move fast. The real problem is and always has been building an extruder that can keep up with the rest of the motion. You also need a print cooler that can keep up with high speed printing because what's the point of printing at 500 mm/sec if the prints look like crap because the printer keeps squirting hot plastic on top of still hot plastic?

Resin printers only move slowly in one direction and don't have problems with ringing. You have a narrower selection of material to print with, and print size is usually limited by the cost of the resin, but if you use a bowden type extruder on an FDM printer you give up the ability to print flexible materials. So any way you go there are trade-offs.

If you want to eliminate ringing from prints and you don't want to spend a fortune, print slower. You can still print with all the same materials. Print quality can be high (you might have to do some extruder tuning, but you'll have to do a lot of that if you try to print very fast).

Speed is over-rated. People can see print quality or lack of print quality, but they can't see how long it took.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Quote
the_digital_dentist
You could make a printer with interchangeable beds of different sizes and use the bed that is just large enough to accommodate each print.
You can print on a sacrificial foam bed without a heater or metal plate.

If you were really concerned about ringing, you'd just print slowly. "Ringing" is a euphemism for printing fast. You're not really concerned about ringing. You really want to print fast, but ringing is spoiling your high speed prints.
If you want to print fast and avoid ringing, the best thing to do is reduce the moving mass and make everything as rigid as possible. That's why people build printers that don't attempt to throw a massive bed around at print speed.

It isn't hard to build a relatively light mechanism that can move fast. The real problem is and always has been building an extruder that can keep up with the rest of the motion. You also need a print cooler that can keep up with high speed printing because what's the point of printing at 500 mm/sec if the prints look like crap because the printer keeps squirting hot plastic on top of still hot plastic?

Resin printers only move slowly in one direction and don't have problems with ringing. You have a narrower selection of material to print with, and print size is usually limited by the cost of the resin, but if you use a bowden type extruder on an FDM printer you give up the ability to print flexible materials. So any way you go there are trade-offs.

If you want to eliminate ringing from prints and you don't want to spend a fortune, print slower. You can still print with all the same materials. Print quality can be high (you might have to do some extruder tuning, but you'll have to do a lot of that if you try to print very fast).

Speed is over-rated. People can see print quality or lack of print quality, but they can't see how long it took.

That all makes sense, I wouldn't say I'm super concerned more just curious.

I was mainly thinking bowden vs direct drive, and for various reasons direct drive seemed better in most cases except for weight on the carriage which in my mind translates to speed and ringing. But if there's still ringing from the bed what's the benefit of bowden on a cartesian style printer.

Like If I were printing long items along the X axis at high speeds?

This led to me thinking how much could I drop the weight of the bed to acomodate the weight reduction on the carriage. Regardless of whether this is productive area of inspection.

Edited 1 time(s). Last edit at 01/20/2022 01:20AM by valsk.

... for "moving bed in XYZ" -- I've seen several samples and machines with this setup - one was a delta CNC-milling setup, the other a "ultrasonic speed metal-jetter" with an industrial robot-arm moving a metal plate as "target" above the jetter to impact-sinter the part onto it

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

Quote
VDX
... for "moving bed in XYZ" -- I've seen several samples and machines with this setup - one was a delta CNC-milling setup, the other a "ultrasonic speed metal-jetter" with an industrial robot-arm moving a metal plate as "target" above the jetter to impact-sinter the part onto it

That's pretty crazy, particularly the last one.

Quote
valsk

Quote
VDX
... for "moving bed in XYZ" -- I've seen several samples and machines with this setup - one was a delta CNC-milling setup, the other a "ultrasonic speed metal-jetter" with an industrial robot-arm moving a metal plate as "target" above the jetter to impact-sinter the part onto it

That's pretty crazy, particularly the last one.

... yes, but it had a pretty "crazy" price too! -- 550.000€

---

Viktor
--------
Aufruf zum Projekt "Müll-freie Meere" - [reprap.org] -- Deutsche Facebook-Gruppe - [www.facebook.com]

Call for the project "garbage-free seas" - [reprap.org]

You don't find much discussion about weight reduction on 'bed-slingers'.

I can't comment authoritatively on the matter as I don't have one, but you could certainly reduce weight in several way I would think.

Carriage plate for mounting the bed could be replaced with a milled or laser cut carbon fiber one.

The bed surface itself: Ditch the glass, those beds aren't known to be particularly flat so why not use something like Garolite which is a resin composite and also doubles as a good print surface as well? A thick sheet of it should be reasonably flat compared to whatever piece of glass it replaced and substantially lighter.

Also, of course there is software compensation for ringing, such as input shaper options that minimize ringing at the expense of a small amount of detail in prints.

Everything comes with compromise, it's up to you which compromises you're willing to accept.

To follow up on Obelisk, a very common i3 clone has a Y carriage made of steel sheet, the replacement carriage from aluminum by a well known supplier shaves off about 170g from the total bed weight (could be 200ish if you replace the original 4 point mount aluminum bed with a 3 point mount one because then you can get rid of a mounting bar). Replacing the glass print surface with a magnetic flex steel sheet shaves off another 150 or thereabouts.

Anything beyond that requires expenses that make it compelling to convert the whole printer to a fixed bed / fixed Z design -- even the parts needed for the optimization outlined above encroach on that (depending on your tools and skill).