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Ready for first test

Posted by mk3a 
Ready for first test
August 29, 2014 05:14PM
Finally have everything assembled and movement seems really good.

I had some trouble getting filament loaded into the extruder cold end. For some reason it would get past the gear and then fail to enter the hole leading outside. After about 20 minutes of fiddling I finally got it to thread through. I fed the end of my filament 90% of the way to hot end.

Now I have a question:

Do I just try to print something? How will the printer know how far to extrude the filament before starting the print? Are there any other steps I need to take first? I'm concerned the filament may jam in the entrance to the hot end the way it did in the cold end. Maybe I'm being paranoid, but due to the rostock mini pro design there is a bit of a gap between the end of the tube coming from the cold end, and the hole in the top of the hot end.
Re: Ready for first test
August 29, 2014 06:08PM
Pull the filament out and use a pair of wire cutters to cut the end at a 45 degree angle. This will reduce the profile of the filament you're trying to get through and make it easier to get past boundaries. You might need to fiddle a bit with the orientation, but it really does make it a lot easier to feed your filament through. Even if the holes line up perfectly, your filament will come off the spool / reel in a curve, not perfectly straight, and can cause it to snag at any gaps or ledges between parts in your hot end.

Heat your hot end to the proper temperature and feed the filament through by hand until you get molten filament coming out of the nozzle, then you're good to go.


[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.
Re: Ready for first test
August 29, 2014 06:11PM
You should be able to feed your filament into the hot end when it's cold until it stops. Have you calibrated your e-steps yet? At least a rough calibration of that should be done before you try and print anything.
Re: Ready for first test
August 29, 2014 06:57PM
Quote
3dkarma
Pull the filament out and use a pair of wire cutters to cut the end at a 45 degree angle. This will reduce the profile of the filament you're trying to get through and make it easier to get past boundaries. You might need to fiddle a bit with the orientation, but it really does make it a lot easier to feed your filament through. Even if the holes line up perfectly, your filament will come off the spool / reel in a curve, not perfectly straight, and can cause it to snag at any gaps or ledges between parts in your hot end.

Heat your hot end to the proper temperature and feed the filament through by hand until you get molten filament coming out of the nozzle, then you're good to go.

The 45-degree angle thing sounds like a great idea.

How do you feed it by hand when the printer is on? Doesn't the motor lock in place?

Quote
brucehvn
Have you calibrated your e-steps yet?

You mean calibrate the amount of filament that gets extruded? Yes I made some adjustments and it seems to extrude exactly the amount I ask for (without the hot end attached).
Re: Ready for first test
August 29, 2014 07:05PM
Quote
mk3a
How do you feed it by hand when the printer is on? Doesn't the motor lock in place?

Depends on what kind of extruder you have. If it's a Wade's, send M18 to the printer to turn off the stepper motors then turn the big gear to extrude.


[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.
Re: Ready for first test
August 29, 2014 07:43PM
I think it is a Bowden. The extruder has no big gear and feeds the hot end via an approximately 1 foot tube.
Re: Ready for first test
August 29, 2014 08:20PM
Can you post a picture of it?


[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.
Re: Ready for first test
August 29, 2014 09:46PM
It is this:
[3dprinterczar.com]
Re: Ready for first test
August 30, 2014 03:12AM
It looks like you can back off the tension arm by unscrewing the cap head screw at the top of the picture, then push through by hand. This will give you a feel for where the issues are further down in the hot end.


[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.
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