1 Topic by jakegraber

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Topic: Nipple Twisting by motor

Ha ha, but seriously. I've noticed in the last few hours that the motor seems to get bogged down and occasionally outright stops while operating. Now, one of the other symptoms I've noticed is a twist in the entire nipple as soon as the motor is turned on. Not only that, but when the motor is no longer powered it spins backwards a few rotations, like something is acting as a spring inside the mechanism.

It's like the auger may be binding against the inner wall of the tube, perhaps either the auger or the nipple are bent. I don't see how this could have happened, I tightened the nipple on the short side of the cutout, and I put the nozzle on, making sure I wouldn't twist the tube. Perhaps the auger came bent? The box was intact, and all the parts were neatly organized...

I'll have to take it apart tomorrow and check that it's linear, but is there anything else I can do to alleviate this issue? It effectively renders my filastruder inoperable, as the binding prevents plastic from being pushed through the machine.

PS: SN# 174

2 Reply by elmoret

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Re: Nipple Twisting by motor

What temperature are you extruding at, and what polymer?

Can you upload a picture of how you assembled the kit?

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3 Reply by jakegraber (edited by jakegraber 2013-07-14 18:38:30)

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Re: Nipple Twisting by motor

I've tried between 175 and 195. I'm extruding ABS. Here's a video showing my problem. I apologize for the quality.

http://www.youtube.com/watch?v=M6BaqBy1CjQ

EDIT: Right now it's low quality because I just uploaded it. Better qualities will become available with time.

4 Reply by elmoret

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Re: Nipple Twisting by motor

You should have checked that the auger spun freely inside the barrel before finishing assembly. If you did this, then neither the auger or barrel are bent.

Spinning backwards when powered down is normal, the whole frame is storing torque.

What ABS are you extruding?

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5 Reply by jakegraber (edited by jakegraber 2013-07-14 20:46:01)

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Re: Nipple Twisting by motor

elmoret wrote:

You should have checked that the auger spun freely inside the barrel before finishing assembly. If you did this, then neither the auger or barrel are bent.

Spinning backwards when powered down is normal, the whole frame is storing torque.

What ABS are you extruding?

It did. I made sure of it. Im extruing the sacrificial plastic that came with my filastruder. Is it usual for the whole thing to twist or the motor to spin quite slowly? You can see the twisting in my video.

6 Reply by elmoret

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Re: Nipple Twisting by motor

Well, the motor definitely won't spin the auger when the nozzle temperature is that cool. You need at least 160degC for the auger to spin the motor, otherwise the viscous drag is far too much for the motor to overcome.

The output of the gearmotor should spin around 1.5RPM.

Get it up to 190C, wait 15 minutes, and try powering the motor up. Do you have a way of checking the temperature independently? A thermocouple or thermistor based probe?

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7 Reply by jakegraber

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Re: Nipple Twisting by motor

The nozzle is reporting a temperature of 190C and the motor is still ceasing. I unfortunately don't have any external way of measuring the temperature. The motor completely stops, after an hour of extruding nice filament. I honestly don't know what to do, because it seems like it works fine for a while and then mysteriously stops.

8 Reply by elmoret

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Re: Nipple Twisting by motor

Is the motor getting warm?

Try 200C and a fan pointing at the motor. Could be a bum motor, though it'd be the first so far.

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9 Reply by jakegraber (edited by jakegraber 2013-07-14 23:34:32)

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Re: Nipple Twisting by motor

Yes, the motor gets almost too hot to touch. Ill try another fan

Edit: scratch that, it gets way too hot to touch. After leaving it to cool for a while, it works fine again. I'm not running it in a warm environment, its about 72F in my house. Bad motor?

10 Reply by elmoret

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Re: Nipple Twisting by motor

Potentially. It's kind of a catch-22 - if the motor's bad, it'll run hot and not produce full torque, making the symptoms you describe. If there's some other issue (incorrect temperature being reported) then the motor has to work harder than normal, heats up, and starts producing less torque.

Let me know how you get on with a fan on the motor. If need be, we can do an exchange.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

11 Reply by jakegraber

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Re: Nipple Twisting by motor

I believe it may be the temperature readout is incorrect. If I let it sit for a while then the motor runs, then after a while it stops. When the temperature readout is 190, a piece of filament barely melts when pressed against the nozzle. What might cause this? It is still incredibly hot so I can't tell how much its off by. I can tell you that it is nowhere near hot enough to make ramen.

12 Reply by elmoret

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Re: Nipple Twisting by motor

A bad thermocouple or a bad PID controller could result in an incorrect thermocouple reading. Boil some water and put the thermocouple in it - it should read 100C.

You can set the PID controller to 250C. The heater isnt powerful enough to go much over 210C as long as the fan's on.

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13 Reply by jakegraber

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Re: Nipple Twisting by motor

elmoret wrote:

You can set the PID controller to 250C. The heater isnt powerful enough to go much over 210C as long as the fan's on.

Well, I set the PID to 220C and it reportedly got there... Which apparently shouldn't happen, so I don't know what to do. However, as the temperature rose the motor started to spin up, and soon it was running full speed.

What I'm having a problem with is finding a point where the motor spins and the filament is satisfactory. At "220"C the filament is a measly 1.3mm in diameter. Just minor changes in temperature, such as those normally occurring as the nozzle cools/is heated in a cycle, change the speed at which the motor rotates.

Also, I've measured the voltage across the motor and its a steady 12.2V, so the power supply is not a problem.

14 Reply by elmoret

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Re: Nipple Twisting by motor

Yeah, there's definitely issues with either your PID controller or your thermocouple. Just as a double check - you have the polarity correct on the thermocouple, right?

What happens when you set it to 200C? 205? It sounds like you're reading around 20C high.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

15 Reply by jakegraber

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Re: Nipple Twisting by motor

elmoret wrote:

Yeah, there's definitely issues with either your PID controller or your thermocouple. Just as a double check - you have the polarity correct on the thermocouple, right?

Yes, very yes. I tried flipping it around and checked the schematic just to be sure. It is most certainly in the proper orientation. Many errors when it isn't. tongue

elmoret wrote:

What happens when you set it to 200C? 205? It sounds like you're reading around 20C high.

Well, when I set it to those values, the PID reportedly gets there, but at that point the motor decides it doesn't want to run and slows down to a halt.

I'd like to mention an observation that my dad made while he was watching the extruder run. Apparently the motor fluctuates in speed even when the barrel is empty. I had let the filament run out to see what sorts of speeds it would spin at without too much friction, but even then the motor sped up and slowed down, albeit never stopping, but there is definitely something wrong. That shouldn't happen, right?

16 Reply by elmoret

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Re: Nipple Twisting by motor

jakegraber wrote:

I'd like to mention an observation that my dad made while he was watching the extruder run. Apparently the motor fluctuates in speed even when the barrel is empty. I had let the filament run out to see what sorts of speeds it would spin at without too much friction, but even then the motor sped up and slowed down, albeit never stopping, but there is definitely something wrong. That shouldn't happen, right?

That's normal, it means there's a blob of plastic left in the barrel that acts as intermittent drag on the motor, but isn't big enough to be pushed out.

What happens when you set to 210C? At 220C, what was the output rate in inches per minute?

If you'd like, we can exchange the motor/PID/thermocouple. Shoot an email to [email protected] if you decide you want to do that.

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

17 Reply by jakegraber (edited by jakegraber 2013-07-15 18:04:00)

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Re: Nipple Twisting by motor

elmoret wrote:

What happens when you set to 210C? At 220C, what was the output rate in inches per minute?

If you'd like, we can exchange the motor/PID/thermocouple. Shoot an email to [email protected] if you decide you want to do that.

When I set it to 210 the motor barely rotates any more. At just under 220, the motor spins at about 1RPM inconsistently, which translates to about 7.5in/min extruded, however the filament is  barely 1mm and is lumpy due to the varied extrusion speeds. It is possible that the PID is correct, and the motor is dying and unable to extrude at correct temperatures. Keep in mind that I extruded several meters of good filament before the motor simply started to give out.

I would be very happy to replace this motor. I'll send an email.