Delay In Extrusion (Nylon)

You don't say which flavor of nylon, but all nylons have some flexibility, some are more flexible than others. With the GregsWade it will be just as you describe -- a delay when starting to extrude. This is due to the filament compressing in the hotend. I have printed a lot of nylon (it is one of my favorite materials) and if you can tell me which blend it is I can get you some more information on settings.

You will want to experiment and note what settings work best with each blend.
A rule of thumb is that it will be hotter and slower than most other filaments.

 

What type of nylon is it?
230, 618, 645, 680, nylon bridge, something else?

Every blend has different characteristics. I almost always use Taulman since they provide detailed specs for the materials. I have tried a couple generic "nylon" filament and those were just junk. See if you can figure out which type of nylon you have.

 

So it is nylon 12:

https://en.wikipedia.org/wiki/Nylon_12

You are not going to have a lot of luck on the Robo with that:

Processing Temp. 255- 275ºC
Bed Temp 130ºC+ -- the company you bought it from says "110c or even higher" which is a bit disingenuous . 'Hotter' indeed....

That bed temp is not workable. The extrusion temps are rather high ass well. They are reachable if you tweaked the firmware to change MAXTEMP, but still quite high.

My suggestion would be to:
1) set the extrusion temp as hot as you can -- 275c would be great
2) set the bed temp as hot as you can (110c is the practical max, but most firmware limits it to less)
3) print as slow as you can. Drop the print speeds by a lot, start by reducing them by 50%

Don't get put-off of nylon by this stuff. It is a rather odd-ball one and starting with that just makes it harder
Let me know what properties of this nylon are you really looking to leverage and we can probably help choose something else to try if you can't get this to work well. All of the others I mentioned I have used (although 230 sux IMHO... avoid it since it is hard to get sorted too)

 

Yep, that is the flexible part of it. Compression into the extruder and then it continues extruding after the gears top to relieve the pressure.

It is possible that it will print better at a higher temperature, it is safe to say with that range of values you are probably good to try it all the way to 280c (I have tried one blend that wanted 310c so.... it is not unheard of to need more heat). Some blends are the opposite of PLA/ABS in that they get stringy when too cold (rather than too hot).

You need to slow down the print speeds as well to help account for the fact that is is extruding slower and reacting slower. I would as I suggested earlier drop them by 50% for a start and see how low you really have to go.

 

The limit of the thermistor Somewhere just north of 300C

You can certainly go as high as 400C (but you need to swap to a thermocouple).
We have one dedicated to higher temp prints.

Every blend of nylon is a little different in terms of best settings, but we have had best results with Taulmans filament as they are very clear on exactly which blend you are getting and what the properties for it are.

Another issue you could have is that it could be 'wet' and nylon becomes almost unusable if it absorbs moisture from the air. Keep is stored with desiccant when not in use.

Try Alloy910 from Taulman. We use that on most outdoor components and devices that will be in rather harsh conditions (like saltwater air).

 

It so very much depends on the vendor. I have tried a few of the other vendors 'nylon' with less than impressive results, some of them were just never produced or stored correctly and I didn't want to waste time trying to dry the filament.

It could just be the nature of nylon-12 as well -- I have not used that blend so I can't speak authoritatively on exactly how it should behave Most of the blends do behave in similar ways though. I really think at this point it is just a matter of learning how nylon-12 works, you probably have good filament.

 

Possibly. Since it is nylon it will be compressible and that will cause a bit of a delay.
As I think I said -- hot and slow are the two general rules for nylon

As an exact opposite to normal (PLA/ABS) if it is stringing a lot try a bit hotter and see if it get better or worse.
Some nylon blends actually string worse when too cool.

It is a terrific material, but not suitable for everything Glad you made progress.

 

IMO nylons are one of the hardest materials to print correctly (expecially in our non enclosed robos) but once you get it dialed in save those settings! Take pictures of them, write them down in a book whatever you need to do to make sure youll always have them otherwise you'll do this all over again! (yes I was silly and didn't do this lol, lots of time wasted retuning everything)