Nozzle size vs speed

People say that if you print with a bigger nozzle, the print time decreases.
In the past we have used 0.4, 0.5, 0.6mm and 0.8mm nozzles, and each time the time has decreased as we increase the nozzle size, and actually increased the speed very slightly, and got quite similar finishes.
We normally print with a 0.8mm nozzle, but recently got a 1.0mm & 1.2mm nozzles, and have been using numerous settings, but haven't used the 1.2mm nozzle yet. It seems that the 1mm nozzle has to print slower than the 0.8mm nozzle? Does that sound right?
To get a half decent quality print with PLA using the larger nozzle and larger layer height, it takes longer than just using 0.8mm nozzle with a smaller layer height, so therefore we are being a little less productive.
So is the 0.8mm nozzle the limit when it comes to actual print speed and time, and anything after becomes slower unless quality doesn't matter?

In principle the print speed should vary inversely with the square of the nozzle diameter, provided that you can maintain linear speed. What problems did you have when you tried to print with a 1mm nozzle at normal speed? I presume you have a Volcano hot end so that it stands a chance of melting the filament fast enough.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

It's also going to depend upon how fast your extruder motor can feed plastic. If your using a volcano nozzle setup, I know the geared extruders have issues with very high speeds which is why E3D's Titan extruder has a 3:1 ratio to be able to keep up. I can also imagine an 8-bit controller might have issues with high speeds if your using a lot of microsteps.

Yes it is the volcano hot end.
printing at the 'normal speed' there is a problem with the layers sticking. And when tweeking the extrusion multiplier, it just gets clogged up (have also changed the temp as well)
The normal speed is 65mm/s sometimes 70mm/s, but with the large nozzle, I have managed to get to 40mm/s with a layer height of 0.7 which provides a workable finish. Just to give you an idea. An object can be printed using the 0.8 nozzle with a LH of 0.4mm, whilst the same object with the 1mm nozzle and a LH of 0.7mm takes a few mins longer

Thats the only issue. Once you get that large and that fast you have to be able to properly heat the plastic that fast as its shooting out the tip.

You might have to crank the temperature up 10-15 degrees when you try and print faster as the plastic will spend less time in the heater block section.

I've got a volcano mounted on my corexy and with the big nozzles you have to slow down or the plastic just doesn't melt fast enough, if I infill above 50mm/s I get blobby infill. I notice on one of the chinese sites someone selling 50w heater cartridges, this might help. So I can print big chunky objects that are very strong, but faster - not really. Maybe a dual heater volcano block, that would possibly do the trick.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

I would be surprised if you can increase your printspeed by using a bigger nozzle.

Its a bit hard to test but you need to find your max extrusion volume and then compare it between the different nozzle sizes.

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PDBeal
You might have to crank the temperature up 10-15 degrees when you try and print faster as the plastic will spend less time in the heater block section.

The volcano should have the thermistor closer to the nozzle instead of close to the heater element. It's this hysteresis, why you crank up the temp for compensation.
IMHO the best position would be on the bottom left corner, away from the heater element.

Edited 1 time(s). Last edit at 02/07/2017 04:16AM by o_lampe.

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o_lampe

Quote
PDBeal
You might have to crank the temperature up 10-15 degrees when you try and print faster as the plastic will spend less time in the heater block section.

The volcano should have the thermistor closer to the nozzle instead of close to the heater element. It's this hysteresis, why you crank up the temp for compensation.
IMHO the best position would be on the bottom left corner, away from the heater element.

The termister cartridge for the volcano sits vertical right next to the nozzle/heatbreak path with the heater cartridge on the other side of the block. The block for the volcano is also roughly 18mm taller than the standard E3D V6 heater block. Your still facing the same time vs temp to get the plastic to melt, so it should be possible to increase the temp to compensate for the time in the nozzle. Your still dealing with thermodynamic properties of heat transfer.

And it definitely helps to coat the heater cartridge and the nozzle threads, with some sort of thermal transfer paste or even copper-slip which is more heat tolerant than silicone based thermal compounds (also helps to get them out again later).

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions