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Bridge Nylon Interface Bulge

Posted: Sat Aug 27, 2016 3:17 pm
by altertalk
I am using a Lulzbot Mini with Bridge Nylon for making rocket parts, including motor mounting centering rings. The issue I am noticing is that the initial laying down of the material on the bed seems to bulge from the original specified model. It's producing a 0.5 mm ring that I have to file off in order for my mounting rings to be flush with the tubes that hold the engine. Is there something I need to do to prevent this?

Also, the Lulzbot website suggests a head temperature of 230C to 240C. At 230C the material is dripping from the head, suggesting to me it is too hot. Is there some better information available for this material?

Re: Bridge Nylon Interface Bulge

Posted: Sat Aug 27, 2016 9:32 pm
by DougZ
Sounds like you're using the quick print profiles in Cura? The first layer is defaulted that way unless you change it is the slicer settings. The idea is to squish it in to the bed a little more than normal.

Switch to expert settings and then look for the Initial Layer Height and Initial Layer Width settings. Only change one thing at a time then check the results. Based on your description you should be able to just change the initial layer width setting from 120% to 100%. Keep in mind changing these settings can affect bed adhesion which may or may not become a problem depending on your model.

As a note, if you change the initial layer height from the default .425 to 0 (which means whatever the specified slicer layer height is set to) you may need to add more skirt lines, or some other change to increase the priming of the nozzle. Otherwise it may start printing your model before the filament has actually started to extrude.

Re: Bridge Nylon Interface Bulge

Posted: Sun Aug 28, 2016 7:39 am
by altertalk
DougZ,

So, I printed a set of rocket parts yesterday, and some of the parts had adhesion issues. After each print in the area of the print, I have been cleaning the bed with IPA (70% available at pharmacies), and then reapplying PVA. Yesterday was one pass with the PVA. This morning I am trying a double pass, first side to side (East-West), and then a second up and down (North-South). with the hopes of better adhesion. Does bed temperature create an issue for adhesion with PVA?

I also noticed that the printer speed is so sharp from part to part that some were shaking loose. Is there a way to set the speed by which it goes so it is not so jerky?

Steve...

Re: Bridge Nylon Interface Bulge

Posted: Mon Aug 29, 2016 5:46 am
by altertalk
Hi,

I went into the expert settings, but found nothing labeled slicer settings. I did find the initial layer thickness and initial layer line width. I changed the initial layer thickness from 125 to 100. But, I have no idea what to use for the initial layer line width. Is there some suggested settings for the expert level?

Steve...

Re: Bridge Nylon Interface Bulge

Posted: Fri Sep 09, 2016 11:50 am
by DougZ
Hi @altertalk, sorry for the delayed response, I've been traveling. I guess one thing to make sure you have set properly is your z-offset. Have you done any testing and/or calibrating to make sure it is set properly? Also what glue stick are you using? I use the Elmer's disappearing purple and have no issues with it. I also have my z-offset so that my layers are about on the money. If you're not familiar with how to set it there's plenty of info in this forum. If you have trouble let me know and I'll see if I can help.

The Initial layer line thickness (mm) by default should have been 0.425, not 100. Think of that as the vertical height of the initial layer of filament being extruded if you were to look at it from the side. I habitually measure the height of the skirts laid down and they're almost exactly always that. They should measure to what you have this set to (if you set it to a value of 0 the initial layer will be identical to the "layer height" in the Quality section of the Basic tab.)

The Initial layer line width (%) setting is where I think you're running into the problem. By default it is set to "125" or 125% of normal width if viewed from the top. The idea is a thicker line to help stick to the bed a little better. So if you're modeling in a specific diameter hole that extra width will affect the diameter thus producing what you're referring to as the ring that needs to be filed off.

You can try setting the following:

Initial layer line thickness (mm): 0.425
Initial layer line width (%): 100

to get a thick line but one no wider than it should be. If you set the thickness above to "0", as previously mentioned make sure you add skirt lines or open the idler and manually push the filament into the extruder after the bed leveling probe sequence has completed and the nozzle is waiting to finish heating up.

Re: Bridge Nylon Interface Bulge

Posted: Sat Sep 10, 2016 9:17 am
by mikronano
Just to throw an idea about the bed adhesion. With all the Taulman nylons, I have been working with the Wolfbite Nitro. I had the same issues with the PVA glue: how many layers, how thick, what temp is the best, how to safely remove it from the PEI sheet and so on. Now, I'm not saying that the Wolfbite Nitro is the bomb but is definitely much better than anything else. And, even though they say it is supposed to be applied on glass, I have found it to be working just fine on the PEI. And it is water soluble. Just spray or carefully pour a little of water and it will dissolve and come off. Some times it works so good that without leaving the water to work a few minutes, you simply can't take the printed part off of the PEI sheet. And it is very easy to apply. It comes with a 1" foam brush and when you're done you simply rinse it and let it air dry and is good again for the next time.

Nylon Bridge is nice and easy to print but it has twice the shrinkage of the Alloy 910. That, and the Wolfbite Nitro, might help you with the adhesion issues and get away with printing a skirt. Also, the Alloy is much much stronger...and more expensive!

Re: Bridge Nylon Interface Bulge

Posted: Sat Sep 10, 2016 9:35 am
by DougZ
Have ever tried Magigoo or do you know if it is safe to use on PEI?

Re: Bridge Nylon Interface Bulge

Posted: Sat Sep 10, 2016 10:05 am
by mikronano
DougZ wrote:Have ever tried Magigoo or do you know if it is safe to use on PEI?
Sorry, I haven't. First time I hear is from you. I had a quick look on the web about it. According to the manufacturer it is designed for ABS and PLA. The nylon chemistry is quite different and its "surface tension" is what makes it difficult to stick on most things. This is why when there is something that says it helps with nylon bed adhesion, then this thing is working only with nylon.

Regarding the PEI sheet safety for Magigoo... I can only guess that it should be ok. And all because it is water soluble. That's the only clue that makes me say is probably ok.

Re: Bridge Nylon Interface Bulge

Posted: Sat Sep 10, 2016 10:52 am
by DougZ
Thanks for the quick reply. After asking you I went to look up the Wolfbite you mentioned and saw that there were different Wolfbite ______ for _____" and realized what you just said. the Magigoo looks interesting for ABS and PLA (though I don't have as much of an issue with those on the PEI).