Topic: Press failing to extrude
My Press, like a lot of your Presses, is having a really difficult time extruding ABS. Here are the symptoms of my problem:
1. The Press generally extrudes the first couple inches of material just fine and then the "clicking" starts and nothing further comes out.
2. I've noticed that this problem is generally persistent in the first layers of the print when the Press is creating layers at the slowest speed possible for best adhesion.
3. The spur gear that drives the filament is eating into the filament at an incredible rate.
4. All temperatures are correct. I've now tried to print at 220, 230, 235, 240, 245, 250 and 255 degrees Celcius. The 245-250 degree setting seems to work best. Lower temperatures cause the filament to get chewed up quickly and higher settings cause the filament to back up without chewing into the filament itself as much.
5. When I just tell the Press to extrude material without printing, it does so fine 99% of the time.
6. When starting a print with a room temperature machine, the problem is NOTICEABLY not as present.
Here's what I know from past experience with other printers:
In poorly designed hot ends, or just some hot ends in general, the heat is not well isolated to the nozzle tip so filament melts pretty far up towards to the spur drive. As plastic generally expands when it is heated, this causes pressure to build up behind the nozzle opening inside the hot end. This pressure can be enough to counteract the force of the spur drive, causing it to spin into the filament and chew it up. Once the spur drive has chewed a cavity into the filament, that filament isn't going anywhere.
ABS typically extrudes at 230-235ish degrees Celcius. The fact that the Solidoodle filament extrudes best around 250 and doesn't really extrude that well at 235 leads me to believe that this is an impure and/or weird custom formulation of ABS. After printing a lot of ABS with other printers, I know what it smells like when it's extruded too. The Solidoodle filament has a weird acrid- far more so than usual- odor.
Here's my theory on what's happening with the Press:
It's a combination of three things and, as I've only attempted to print with the included Solidoodle material so far, I'd love to hear input on this.
1.) The hot end is heating up the filament too far into the hot end body causing a pressure build up.
2.) The tension wheel that presses the filament into the spur gear is a little too strong.
3. The included Solidoodle ABS sucks big time and can't handle being compressed by the spur gear, nor can it handle being extruded through the hot end as designed in an effective manner.
This is why the filament extrudes fine when it's just being extruded without printing- it's not in the hot end body long enough to heat up outside of at the very nozzle tip. It's also why the printer generally prints okay when it's printing for the first time from the "cold" room temperature state; the hot end body and the drive head haven't heated up yet.
Possible fixes:
Heat up the hot bed manually before initiating the print. That way the hot end isn't sitting there heating up the hot end body and extruder body while the hot bed is heating up.
Change out the filament for something of a known higher quality like the Makerbot ABS.
Add another fan to the extruder body to keep everything cooler.
I'm going to try a Makerbot ABS next to see if that fairs any better. I'll report back either way but it may not be for a day or two.