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Author Topic: Hot end heat up time  (Read 653 times)

fettsvett

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Hot end heat up time
« on: November 26, 2012, 05:53:36 PM »
Hi all,

I recently got my Bukobot assembled and working, I was wondering, what is the 'normal' amount of time it takes for the hot end to heat up? In the one case that it has heated to 200 C it took at least 20 minutes, and now it's hovering around 178-180 C without ever (after 40 minutes of waiting at least) breaking past 185. I have the fan blowing on only the upper part of the assembly (the part that the fan shroud is made to direct air to) Am I doing something wrong, is my ambient temperature too low, or do I have a defective hot end?

Thanks!

fettsvett

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Re: Hot end heat up time
« Reply #1 on: November 26, 2012, 11:52:26 PM »
For everyone else: I talked to Diego (I believe) on the phone, He told me that it is most likely an issue with the ambient room temperature and that I could try insulating the heating block with the kapton tape that's included in the kit. I will try it tonight and update this post so anyone who has this issue knows the resolution (fingers crossed). If that doesn't solve the problem I'll be heading into deezmaker to get them to have a look. Otherwise, it's a possibility that my heating element performs too poorly and I'll need a replacement.
« Last Edit: November 26, 2012, 11:54:03 PM by fettsvett »

fettsvett

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Re: Hot end heat up time
« Reply #2 on: November 28, 2012, 06:23:11 AM »
OK, I've tried the Kapton tape trick and it bought me a few degrees, though not enough to hit above 183C or so. This is obviously unacceptable as I have the vanilla model and need to be well over 200C in order to print ABS - I'm trying this at an ambient temperature of 65F or ~18C (is this an unheard of ambient temp for printing?) . I will head into deezmaker next weekend, my printer will obviously be out of commission until then, the hot end seized up while trying to print at 175-185C (at the hottest I could get it) and the motor that feeds filament into the hot end is slipping. It sucks to have a new toy that doesn't work.

Forgot to mention, Diego (or whoever I talked to on the phone) advised me that 180 was an acceptable temp to print PVA at, though the documentation says at least 185 - 195 depending on stock.
« Last Edit: November 28, 2012, 06:34:06 AM by fettsvett »

Diego

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Re: Hot end heat up time
« Reply #3 on: November 30, 2012, 07:03:47 AM »
Sorry about the trouble on this. It can be tricky to trouble shoot things like this, but bring it in and we'll figure it out for you.

whosawhatsis

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Re: Hot end heat up time
« Reply #4 on: December 01, 2012, 10:58:10 PM »
Check the Voltage switch on the side of your power supply. In the US you will need it set to 115V, but they come factory-set for 230V because plugging a device expecting 230VAC into 115VAC is safe, but the reverse is not. If the supply expects 230VAC and is only receiving 115VAC, it will still put out ~12VDC, but the current capability will be lower, so you are likely to see voltage drops when you try to draw current.

There is also a potentiometer on the power supply that can be used to increase the voltage. It can go up to about 14V. You don't want to turn it up all the way, but it's perfectly safe to go up to about 13V, and the performance will increase a bit.

PhracturedBlue

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Re: Hot end heat up time
« Reply #5 on: December 02, 2012, 09:32:38 PM »
You might try disabling the fans on the hot-end.  This made all the difference for me.  No problem hitting 220C without the fan, while I could barely hit 180 with the fan on.

MacD

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Re: Hot end heat up time
« Reply #6 on: December 03, 2012, 05:59:38 PM »
If I turn off the fan, won't the heat that I was originally dissipating move up to the plastic parts.  Will that be a problem?  I am stuck at about 204, needing to get up to 220. 
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MacD

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Re: Hot end heat up time
« Reply #7 on: December 03, 2012, 06:11:28 PM »
Another related question: why does the extruder go on for ~4 seconds every 30 seconds?  Is this something in the firmware?
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whosawhatsis

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Re: Hot end heat up time
« Reply #8 on: December 03, 2012, 06:30:40 PM »
That it to keep the extruder primed (if it sits hot and oozes there will be an air pocket in the tip), to keep too much heat from creeping up the filament, and to keep the plastic in the nozzle from sitting hot too long. You should not leave your nozzle hot without extruding anything for extended periods of time, so we activated a firmware feature that automatically feeds a bit at a regular interval when the machine is idling with a hot nozzle.

Turning off the fan will allow heat to creep up the insulator, and is not recommended. I did notice a little air leakage down from the fan shroud on mine last night, and I fixed it by bridging the gap between the fan shroud and the plate below the heatsink with a piece of kapton tape.

MacD

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Re: Hot end heat up time
« Reply #9 on: December 03, 2012, 07:24:42 PM »
Kapton tape across the gap between the plastic and the shelf does the trick for me.  I am now steady at 220. 

I also tested while heating the printbed up to 110, and the extruder temp holds steady.  Previously (sans tape), the extruder temp dipped from 204 to 198 while the bed was heating. 

I notice that the extruder starts to extrude around 180-185*C.  Is this okay with ABS?  I haven't seen any problems yet, but I don't want there to be long-term problems because the ABS may be too stiff at that temperature.

Thanks!
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whosawhatsis

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Re: Hot end heat up time
« Reply #10 on: December 03, 2012, 10:48:15 PM »
That shouldn't be a problem. You can push ABS through at 170C or possibly lower as long as its slow and has plenty of time to get up to that temperature, which it does in the case of the auto-priming.

 

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