Actually it is a ordinay 1 phase 220v motor with capacitor to start it, but if you remove the cap and rewire the windings
it is possible to run them on 3phase 220v. I am using a Hitachi VFD FRD 720. http://www.acpd.co.uk/mitsubishi-d700-inverters.html
Really cool to drive with. There are 100's of parameters to change in it. Even network connectable and stuff.
The motor has a 36rpm gearbox, and with the vfd i can run it at 0-72rpm with full torque at any speed

Why do you think less insulation will mean less load on the motor? That doesn't make sense to me.

He's correct.

With less insulation, you end up with a shorter melt zone. With a shorter melt zone, you end up with less torque required.

You also end up with worse mixing, and reduced output rate relative to an insulated barrel.

Now i run a 3 phase motor with a frequency converter for speed control. Expensive yes.

I have badly twisted welded steelframes with it, and also crushed several thrustbearings because of the force.
The present version is a dual heated/dual controlled chamber version.

I am not doing it for someone else, just for myself to learn what does what.

That sounds pretty cool. Maybe take some pictures of your filament and while your at it take a picture(s) of your extrudes. Are you running of 3 phase, or using a converter? If a converter what type?

AndersE wrote:

And also many have insulated also the barrel.
That i think is wrong. You want to get rid of the heat from the barrel, not trap it there.

What is the reason for this statement?

By leaving the barrel uninsulated, you reduce the effective L/D ratio - it is already lower than typically recommended for the plastics we use. Insulating the barrel improves filament throughput, by increasing the average coefficient of friction in the barrel.

I've read several books on polymer extrusion - the design decisions I made are based on commonly accepted design practices in industry.

Well, it was just my thought that you would want less load on the motor, as it will have when not insulating the barrel.
I know that there are many compromises to be done.

I have myself built 10 different versions of my own extruder and have seen what different stuff do to speed/quality.
One was fast but got to big variance in diameter, one was extremely slow with excellent diameter. One was quick on ABS but slow on PLA and one vice versa. This by using diffrent auger manufacturers (diffrent angles/distances on the "threads")
I ditched the wipermotor/small motor with gearbox versions early because of poor speed control and power.
Now i run a 3 phase motor with a frequency converter for speed control. Expensive yes.

I have badly twisted welded steelframes with it, and also crushed several thrustbearings because of the force.
The present version is a dual heated/dual controlled chamber version.

I am not doing it for someone else, just for myself to learn what does what.

On many movies on youtube i have seen of the filastruder, i can clearly hear that everytime the heater goes on, the motorspeed change.
Or is it something else i hear? It sounds like "weeee....oooo....weeee....ooo"

If it is so, is the heater and motor running from the same supply? Then the heater drops the voltage so much that the motor gets less speed (underdimensioned powersupply). It should then be impossible to get a consistent diameter of the filament.

The power supply is not underrated. The Filastruder draws about 4.5 amps, the power supply is rated for 6 amps.

No power supply has perfect load regulation. Even expensive power supplies like a Meanwell have load regulation of about 2%. In practice, the power supply sits at about 12.1v with the heater off, and 11.9v with the heater on. That is less than 1% voltage difference. As you probably know, the output speed of a DC motor is proportional to the supply voltage, so we would expect the motor speed to vary +/- a few percent, usually 1%.

The human ear has a pitch resolution of 0.25%. Therefore, the human ear can pick up very small changes in pitch (which is also proportional to motor speed). The fact that you hear a difference in speed is pretty meaningless.

Next, it is important to consider the error introduced by motor speed variation relative to other sources or error. The pellets are oriented randomly, meaning that they do not have uniform density. This results in a mass feed rate varying by roughly 10% - so the motor is nothing compared to this.

Finally, we can consider empirical results. Users report that the filament diameter tolerance is +/-0.05mm without a winder, and +/-0.02mm with a winder. This is about a 2-5% variation in filament diameter.

What is the reason for this statement?

By leaving the barrel uninsulated, you reduce the effective L/D ratio - it is already lower than typically recommended for the plastics we use. Insulating the barrel improves filament throughput, by increasing the average coefficient of friction in the barrel.

I've read several books on polymer extrusion - the design decisions I made are based on commonly accepted design practices in industry.

On many movies on youtube i have seen of the filastruder, i can clearly hear that everytime the heater goes on, the motorspeed change.
Or is it something else i hear? It sounds like "weeee....oooo....weeee....ooo"

If it is so, is the heater and motor running from the same supply? Then the heater drops the voltage so much that the motor gets less speed (underdimensioned powersupply). It should then be impossible to get a consistent diameter of the filament.

And also many have insulated also the barrel.
That i think is wrong. You want to get rid of the heat from the barrel, not trap it there.

Oooooh Tim's gonna chew you up lol

If it is so, is the heater and motor running from the same supply? Then the heater drops the voltage so much that the motor gets less speed (underdimensioned powersupply). It should then be impossible to get a consistent diameter of the filament.

And also many have insulated also the barrel.
That i think is wrong. You want to get rid of the heat from the barrel, not trap it there.