SHoutzager
Posts: 111
Joined: Sun Jan 03, 2016 4:02 pm

Gaps in top and bottom layers

Wed Oct 31, 2018 2:58 pm

If you check out the picture you will see small gaps in the top of this print. I have set the multiplier to 1.25 after it usually was 1.1 and prints still have gaps. New nozzle and heater block. Checked the filament and it is 1.75mm. Any ideas? :roll:

https://www.dropbox.com/s/uenwr4j0y7uqd ... 7.jpg?dl=0

airscapes
Posts: 273
Joined: Tue Mar 06, 2018 10:35 am
Location: Philadelphia PA Area

Re: Gaps in top and bottom layers

Wed Oct 31, 2018 4:43 pm

starting height too high?

zemlin
Posts: 263
Joined: Mon Feb 01, 2016 11:36 am

Re: Gaps in top and bottom layers

Wed Oct 31, 2018 5:00 pm

Partially clogged nozzle.
inadequate drive pressure in the extruder.
Print speed too high.

horst.w
Posts: 781
Joined: Fri Oct 17, 2014 5:00 pm

Re: Gaps in top and bottom layers

Thu Nov 01, 2018 4:40 am

Without your Factory-file nobody can find out the issue.

I guess (!!!)

... its the Extrusion Widht: if the bore are e.g. 5 mm you have only 5 lines to fill the surface, makes an ExtrusionWidth of 1 mm or more. This is as hight as the extruder can not feed enough material. An other thing, a 0,40 mm nozzel has only 0,8 mm surface on the bottom; perhaps you have a mismatch between mm and inches.


Regards
horst.w
GER

SHoutzager
Posts: 111
Joined: Sun Jan 03, 2016 4:02 pm

Re: Gaps in top and bottom layers

Thu Nov 01, 2018 11:21 am

Thanks for the replies. This printer is 5 years old and this issue happened off an on. It is a Makerbot Replicator 2. I had been printing with a .3mm nozzle and it was working well. I replaced the nozzle with another .3mm and it would clog up.

So I believe it just isn't building up the correct pressure as someone noted. What could cause that?? Maybe the gears don't grip on the filament as well as they used to. The spring is good to go. :geek:

horst.w
Posts: 781
Joined: Fri Oct 17, 2014 5:00 pm

Re: Gaps in top and bottom layers

Thu Nov 01, 2018 12:30 pm

If the extruder clocks, the preasure is to hight.

The new nozzle has the same dimensions and the same Material as the old one?
Full metal hotend or PFTE tube?
The hotend was heated up when you have mounted the new nozzle?
Any changes of the hotends cooling or object cooling ?

I had the last days filament material what I couldn't print out with a 0.35 nozzle, with a 0.50 nozzle it runs fine. Whatever the reason was.
But the new 0.35 nozzles are steel and the old one was brass. Can make the difference because they have different coefficient of thermal conduction.

H.

zemlin
Posts: 263
Joined: Mon Feb 01, 2016 11:36 am

Re: Gaps in top and bottom layers

Thu Nov 01, 2018 1:08 pm

horst.w wrote:
Thu Nov 01, 2018 12:30 pm
But the new 0.35 nozzles are steel and the old one was brass. Can make the difference because they have different coefficient of thermal conduction.
303 Stainless Steel has 14% the thermal conductivity of 360 brass - so if enough plastic is being pushed through the nozzle a stainless nozzle might not be able to maintain temperature at the nozzle/plastic interface and could require lower print speeds. I haven't printed much with stainless nozzles and haven't seen this in action, but it's certainly a possibility.

303 SSTL
16.2 W/m-K 112 BTU-in/hr-ft²-°F

360 Brass
115 W/m-K 798 BTU-in/hr-ft²-°F

User avatar
dkightley
Posts: 2040
Joined: Tue Mar 10, 2015 4:09 pm

Re: Gaps in top and bottom layers

Thu Nov 01, 2018 6:36 pm

A few things to check on the MakerBot Rep2....

Are you using a printed replacement spring loaded lever upgrade that replaces the "squash an o-ring" filament clamp device. If not, get one!

If you are, check the front fan runs all the time. If it doesn't the above printed spring lever will soften and bend.

And if you do have a printed lever, check it has not bent, causing the lever to hit the plastic piece at the top through which the filament feeds, loosening the grip on the filament.

I use a PTFE lined nozzle barrel on both by BotR2s. the liner make the filament run smoothly......but you have to ensure the head cools down sufficiently after printing so the fan cuts out. Don't power down before it stops! Otherwise the PTFE tube will be damaged...and stop the head working.
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

SHoutzager
Posts: 111
Joined: Sun Jan 03, 2016 4:02 pm

Re: Gaps in top and bottom layers

Fri Nov 02, 2018 1:07 pm

Thanks for all of the replies. I just ordered a new fan that cools the heat sink fins and a new spring for my filament grip. It is the Makerbot injection molded version that came out a couple of years after the Replicator 2 was launched.

I may need a PTFE liner for the cold zone. Who sells one?? :geek:

User avatar
dkightley
Posts: 2040
Joined: Tue Mar 10, 2015 4:09 pm

Re: Gaps in top and bottom layers

Sat Nov 03, 2018 5:21 pm

Search on Ebay or similar sites...
Doug Kightley
Volunteer at the National Tramway Museum http://www.tramway.co.uk
Railway modeller and webmaster at http://www.talkingtgauge.net

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