Tips for "Rubber-Like" Filament

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JuliaDee
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Tips for "Rubber-Like" Filament

Post by JuliaDee » Tue Jul 30, 2013 2:45 am

It looks as if 3dprintingsystems.com has removed its "rubber-like" filaments from its website, but FWIW I've finally gotten around to seriously trying to get them to work. The white-ish one (I can never remember which is "number one" and which is "number two") is of limited interest to me right now as it's not very soft or flexible. A brief try indicated some platform adhesion difficulty.

I then switched to the clear one, which was mentioned here in a recent post on printing an RC car tyre. This clear material is very soft and gummy right off the spool.

I started with a number of assumptions based on my past experiences with PLA and nylon. I figured low heat, fast printing, and high layer thickness would be the way to go in order to avoid a pile of mush. All of these assumptions were wrong. At low heat (230C) it doesn't extrude well if at all. At fast print speeds and high layer thicknesses it just slings goo all over the place - the material has a very low viscosity as it extrudes, and at 0.3mm layer thickness it wasn't adhering to the layer below.

So to make a long story short, I achieved success by using "fine" printing speed, 0.2mm layer thickness, and normal ABS print temp (on an Up Plus). The slow speed and small layer thickness ensures that the bead being extruded lays on and adheres to the one beneath. Opening the fan duct seemed to help printing accuracy by cooling the material shortly after it leaves the nozzle - the material retains a lot of heat and stays molten a bit too long otherwise.

Now here's the real discovery. The filament feed stopped midway through my print a few times. Harkening back to PLA nightmares, I turned on my feed gear cooling air, thinking that I was getting pre-melt. Didn't help. Tried various pressure settings on my Petitclerc feed mechanism; didn't make much difference. I withdrew the filament and saw no signs of it having been chewed up by the feed gear (or of pre-melt), and the feed stepper wasn't jamming or making clicks so it wasn't a nozzle clog. Everything looked peachy. Hm.

When I fed the filament back in, the feed gear would grab it aggressively and pull it right in - the soft, gummy material seems to give the feeder a great grip. So what's the problem? My hypothesis is that it's very sensitive to tension on the filament as it pulls off the spool. The filament is so soft that it stretches a lot even under moderate tension, and as it stretches, its diameter decreases, causing feed slippage. Furthermore, the gummy filament sticks to itself on the spool, adding to the normal tension caused by having to turn the spool.

I switched to an overhead spool and babysat the thing while it printed, pulling a few feet of slack at a time off the spool in advance the get it un-stuck from itself. Eureka, no feed failures!

Adhesion to perfboard is superb. As Bruce has reported, you'll need to cut the raft off your part with scissors or a knife. Vertical support can be ripped off pretty easily with needle-nose pliers. "Dense" support underneath horizontal surfaces: forget it, you're not getting that off.

I do hope Bruce and others continue to pursue elastic/rubber filaments, there are many many applications for them.

roller
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Re: Tips for "Rubber-Like" Filament

Post by roller » Tue Jul 30, 2013 5:10 am

Great info - thanks!

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wilsonj
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Re: Tips for "Rubber-Like" Filament

Post by wilsonj » Tue Jul 30, 2013 8:55 am

Nice work Julia. This soft stuff certainly can be tricky to make work. Especially on a stock UP ( I know yours isn't) I got soft PLA to work on a bowden system, but I had to up the temp, like you did, and drop print speeds to 15mm/s !
Regards
Jamie
3DPrinterGear.com.au

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wackojacko
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Re: Tips for "Rubber-Like" Filament

Post by wackojacko » Tue Jul 30, 2013 10:54 am

Just to let everyone know this will be back in stock in about 4 weeks. Thanks for the tips Julia, it must be fed into the printer with no tension on spool etc. The parts are super stretchy and this has a great memory.
Bruce
http://www.3DPrintingSystems.com

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JuliaDee
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Re: Tips for "Rubber-Like" Filament

Post by JuliaDee » Tue Jul 30, 2013 3:29 pm

Photos of the part. It's 55mm long overall, the O.D. of the "shaft" part is 12mm and the I.D. is nominally 8mm but printed at about 7.5mm. The flutes on the outside of the skirt are 3mm wide and 2mm deep. I'm pleasantly surprised by the level of detail, and the part is quite strong (very good inter-layer adhesion).
IMG_5373.JPG
IMG_5373.JPG (143.73 KiB) Viewed 9518 times
IMG_5375.JPG
IMG_5375.JPG (132.91 KiB) Viewed 9518 times
IMG_5372.JPG
IMG_5372.JPG (127.76 KiB) Viewed 9518 times

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DrewPetitclerc
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Re: Tips for "Rubber-Like" Filament

Post by DrewPetitclerc » Tue Jul 30, 2013 4:06 pm

Wonderful post Julia, nice detail of steps to success.

Regards
Drew
Drew Petitclerc
Petitclerc Designs
Owner/Senior Principal Designer, prototype, tooling and test equipment design and 3D printing
http://flash-graphics.deviantart.com/
http://www.thingiverse.com/DrewPetitclerc

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JuliaDee
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Re: Tips for "Rubber-Like" Filament

Post by JuliaDee » Thu Aug 01, 2013 1:26 am

Thanks, Drew! Still having some feed problems again today, though :( I'm going to try next time with a fresh clean nozzle, but I'm thinking that this filament maybe should be produced slightly oversized, say, 1.9mm diameter instead of the nominal 1.7 or 1.75mm. It's squishy enough that it should still go through everything it needs to go through, and the larger diameter might improve feeder grip and improve flow at the same time. I notice when I extrude manually that the extrusion is very thin, and the increase in material flow from the larger diameter filament might help it keep up with the Up's relatively fast head movement.

I guess on a more open platform you could tweak all the printing parameters to better suit this material but for now all I have is my Ups...

julia

whiterock
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Re: Tips for "Rubber-Like" Filament

Post by whiterock » Fri Aug 02, 2013 6:47 am

It's such a great love to see this all...
You guys have done a great job I am looking to get more and more good enough knowledge..
Keep sharing.. Cheer..



medical scale
Last edited by whiterock on Mon Jan 13, 2014 7:34 am, edited 1 time in total.

realrouge
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Re: Tips for "Rubber-Like" Filament

Post by realrouge » Sat Aug 03, 2013 7:07 pm

It was almost like I read my own experience :)
Also found ABS setting was doing the job instead of PLA and also noticed the stickyness of the spool.

I had bought Flex PLA from Formfutura (http://www.formfutura.com/3d-printing/f ... tural.html)
Bought it beacuse I wanted to print a paddle ring which I lost. Measured the one I had and designed it in Cubify Invent (result: http://www.thingiverse.com/thing:112481)

Although the original ring is a bit more flexible the one I printed is now on the paddle!

Will add irl pictures to the thingiverse soon.

I also noticed that the raft was a bit harder to remove then abs ones. Maybe try the open door aproach...

cheers

btw I have a Up! Mini and used v1.19 software (have 2.0 now)

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