Teflon spacer replacement

[tinkergnome 927]

Will this avoid the head collision? How?

 

No no, this was the wrong answer - respectively the wrong thread....

Just ignore me...

 

[swordriff 119]

Hey Tinker... We are good..

You had the right answer to part of the problem!

Take care.

[b.rauter 1]

Hello everyone,

after a long time of having troubles with the original UM2 hotend (mainly with the teflon spacer).

I already wanted to build a E3D hotend into my UM2. But because there was less to find on the internet about the conversion, I decided to try something else to improve the Teflon part in the hotend.

This topic (http://umforum.ultimaker.com/index.php?/topic/9107-deformed-teflon-fix-use-a-bit-of-bowden/) gave me the idea to use a simple piece of PFA bowden as a cheap wearing part you can easily replace without waiting 3 weeks to get a spare part.

Also the PFA bowden has better mechanical properties than then the glass fibre reinforced PTFE so i hope it will also last longer.

I machined the upper part of the PTFE Coupler out of aluminium, using a lathe and inserted a simple piece of PFA bowden. The bowden should fit tight into the aluminium part.

IMPORTANT, the cutted surface of the PFA bowden has to be perfectly straight and perpendicular otherwise the hotend will leak.

I also used a lathe for that, but printing a sleeve to cut perfect straight should also be possible.

Until now i tried printig with Colorfabb XT for a few hours and I`m quite happy with the results. My UM2 prints as expected like with a new PTFE coupler. Unfortunately i was stil not able to solve all my problems with XT but I'm sure the reason for them isn't the PTFE coupler.

Best regards

Boris

 

[tinkergnome 927]

Interesting idea!

Do you plan a batch production?

If you need testers... feel free to ask me...

Alternativly: are you willing to sell some prototypes..?

 

[ccw1984 1]

Since my PTFE spacer failed recently (documented here) I've been reading through the forums and this thread with fervor and hope. It sounds like the results with Vespel, or some sort of insulating ring, between the PTFE and hot-end are very promising.

I saw someone suggest a teflon spray (for gun parts) and was wondering if that would work on ceramics, to eliminate the PLA sticking issue.

 

So i will start measuring the friction of the new parts and the vespel ring hopefully this week. we also have some parts made in duratron and other materials.

i will check if i can post my results on the tests here in the forum lets see what the tests reveal.

 

Any updates on testing and/or results?

 

@Korneel

Loose the Harbor Freight Calipers like they were on fire!

Trust me

 

Care to explain? I think those are the same ones I just got to measure filament diameter. Recommendations for better ones?

http://www.amazon.com/Inch-Digital-Caliper-Extra-Battery/dp/B0002JFMIO/ref=sr_1_1?ie=UTF8&qid=1423854439&sr=8-1&keywords=caliper

 

[ccw1984 1]

So I received a new PTFE coupler and cut the old one in half to see what was going on. The pictures and descriptions are on the following thread:

http://umforum.ultimaker.com/index.php?/topic/9295-switching-between-pla-and-abs-thoughts-on-under-extrusion-clogging-burnt-pla/?p=95502

I'm wondering if there are any easily attainable and machinable materials that would work as a heat break between the PTFE and brass, I know we've been looking at vespel and the I2K stuff but they're expensive, hard to obtain, and hard to machine. Maybe a sacrificial PTFE washer that rests between the coupler and brass, that can be easily discarded and replaced when it deforms.

 

[swordriff 119]

So I received a new PTFE coupler and cut the old one in half to see what was going on. The pictures and descriptions are on the following thread:

http://umforum.ultimaker.com/index.php?/topic/9295-switching-between-pla-and-abs-thoughts-on-under-extrusion-clogging-burnt-pla/?p=95502

I'm wondering if there are any easily attainable and machinable materials that would work as a heat break between the PTFE and brass, I know we've been looking at vespel and the I2K stuff but they're expensive, hard to obtain, and hard to machine. Maybe a sacrificial PTFE washer that rests between the coupler and brass, that can be easily discarded and replaced when it deforms.

 

Hi CCW1984!

A sacrifical Teflon spacer will help! Mind you, these parts need to be cut in a precision lathe (drehbank), or you will suffer problems. Anders and I are currently working on bringing out a special wafer "chip", which we manufacture in an increadibly tough material. We call it he "I2K", and can take 300C continuously,protecting the Teflon coupler.

I am confident it will be availbale in March. Currently, it looks like it will be supplied together with a

custom top end coupler (replacing the existing Teflon piece), since we have reports from our testers that the pressure on the Teflon is already high and with the inserted chip will be even higher.

The new coupler will be available in two materials, Teflon, and a special compound which is even slicker than Teflon.

For quite some time, Ultimaker have been supplying a "glass filled" Teflon coupler.

Personally, subjectively, and privately, my opinion is that the glass filled one has much higher friction than the

"old" one, (try it "dry" by pushing cold PLA through it.. ). It also compromises one of Teflon`s coolest features of becoming more slick under increased pressure and thirdly I fail to recognize any higher boiling point.

Try seeing it this way; adding glass to stearine when making candles yourself at home (everyone is still doing this, right?); does it really increase the melting temperature of the stearine? Please surprise me..

Theoretically, the glass filling could help the Teflon a little, in that the thermal conductivity of glass is 4 times higher than Teflon, thus theoretically helping to spread the evil from the hot end top end a little.

Mind you, we are looking at W/(m K) figures of 0.25 (Teflon), 1.0 (Glass). Compare it to

brass (the material of the hot end) which is just screaming the energy upwards, figure 110.. Capito?

No, we need something in between which will act as an isolator, it must be slick, keep its shape, not conduct thermal energy, etc..

 

[ccw1984 1]

I had a few thoughts on this, and I think the glass-impregnation is not to increase it's resistance to temperature, but rather to give it more structural strength at those higher temperatures. To decrease the chance of that 'indentation' we see at the base on the failed couplers.

http://en.wikipedia.org/wiki/Fibre-reinforced_plastic

"Fibre-reinforced plastics are a category of composite plastics that specifically use fibre materials to mechanically enhance the strength and elasticity of plastics."

But yes, there is room for improvement and I'm eagerly awaiting the fruits of your labors.

 

[swordriff 119]

Nice try, my American friend!

-but this glass is not a fiber... it is a filler!

[ccw1984 1]

Erm?

I'm assuming they use something like this:

[urlhttp://catalog.fluoropolymerproducts.com/viewitems/reinforced-ptfe-teflon/glass-filled-compounded-teflon-ptfe-2?&forward=1[/url]

http://catalog.wshampshire.com/Asset/psg_teflon_ptfe.pdf

http://www.theplasticshop.co.uk/glass-filled-ptfe-sheet-rod.html

Which all refer to the glass-filled PTFE as "reinforced with glass fibre"

Glass fibre material

Further information: Fiberglass/url]

"Fiberglass reinforced plastics" or FRPs (commonly referred to simply as fiberglass) use textile grade glass fibres. These textile fibres are different from other forms of glass fibres used to deliberately trap air, for insulating applications (see

 

[swordriff 119]

Ok you are good!

The only thing I can try now, hanging on the edge of my own grave , is that

the Teflon coupler can not be moulded or injected...

[gr5 2,265]

y first PTFE spacer is likely gone and I am looking at alternatives

 

I'm sure UM will send you a new one if you convince them (possible with photo?) that the old one is bad. They officially extended the warranty to 1 year retroactively and also they are unofficially replacing broken parts for ultimakers even older than 1 year (if you don't yell at them too much). So there is a good chance you can get one for free if you open a ticket.

 

[randyinla 14]

Hmm. I'd say that being in a pan heated beyond 163°C is a pretty untenable place for a bird to be, and is quite likely to lead to bird deaths. If the bird isn't in the pan then I find it unlikely that it would be close enough for any PTFE vapours from cookware to trouble it. So, I'd say that "unconfirmed" is probably putting it lightly. My suspicions would tend more towards "totally made up".

Perhaps if we strapped a fan to the bird's back?

 

[Anders Olsson 136]

I had a look at the PTFE-spacer again yesterday:

It has logged 225 hours now with the 1 mm Vespel washer protecting it now.

Since I missed logging some prints it probably has been running 250-300 hours by now though.

I have been switching back and forth between ABS and PLA, and the last few hours I printed XT-CF20.

No problems at all so far.

Swordriff will hopefully have similar washers "I2K", available soon for those of you who want to try.

I am thinking of making a more advanced version of the spacer, taking advantage of both PTFE, Vespel and a heat sink.

Hopefully there will be time to try this at some point.

 

[densohax 0]

I had a look at the PTFE-spacer again yesterday:

 

It has logged 225 hours now with the 1 mm Vespel washer protecting it now.

Since I missed logging some prints it probably has been running 250-300 hours by now though.

I have been switching back and forth between ABS and PLA, and the last few hours I printed XT-CF20.

No problems at all so far.

Swordriff will hopefully have similar washers "I2K", available soon for those of you who want to try.

I am thinking of making a more advanced version of the spacer, taking advantage of both PTFE, Vespel and a heat sink.

Hopefully there will be time to try this at some point.

 

Sounds good

I'm still on my PTFE red tubing coming from my Thing-O-Matic with no issues here...

 

[sebastian 0]

Hi guys,

just to give you an update: In the last months we did some tests with spacers made of Torlon (5030 and 4301) and Vespel (SP-3). None of them works properly with PLA. The nozzle is jammed within one or two hours.

I would love to try Duratron as material, as glloq seemed pretty happy with his version (http://umforum.ultimaker.com/index.php?/topic/7024-teflon-spacer-replacement/page-7&do=findComment&comment=77693). Does anyone have a source for Duratron?

Sebastian

 

[gr5 2,265]

Instead of making isolators you should make a 1mm thick washer to separate the teflon isolator from the heater block. Anders did an experiment with a thermocouple down inside at the bottom of the isolator and was able to lower the temperature of the isolator by 100C I believe. With just a 1mm washer.

You are much less likely to jam with a thin washer for two reasons:

1) Less surface area to stick to.

2) The washer is close enough to the hot zone that the filament should be above glass temperature in this region. At least for PLA.

 

[gr5 2,265]

In the last months we did some tests with spacers made of Torlon (5030 and 4301)

 

Wait - do you mean isolators or just a washer shaped spacer?

 

[sebastian 0]

We made isolators. I would favor a one piece solution but washers could be a workaround...

 

 

[gr5 2,265]

So Swordriff and Anders are selling i2k "washers". They seem to work very well. They are only 16 euros. I believe Anders put hundreds of hours of testing into it but he's a high temp guy I think (ABS?). Anyway I will be getting one soon also.

http://3dsolex.com/

 

[randyinla 14]

I recently picked up a 7x14 mini-lathe. Ordered a 3' length of 1/2" PTFE for under $10 from Amazon. Will try my hand at turning my own spacer and see how it works. PTFE is PTFE, right? I mean, is there "the good stuff" and "the bad stuff"? $10 seemed pretty cheap. If nothing else, I could make a ton of flat washer-type spacers to go between the one from Ultimaker and the hot end. Would make the official spacer last longer, no?

 

[DidierKlein 729]

The problem i see with spacers is that some material could go between it and the insulator, it will then cause a nice clog that would be hard to clean, i really feel that it's better to have the insulator in one piece

 

[swordriff 119]

RandyinLA:

If you make a spacer with PTFE to go between the Teflon coupler and the hot end, it WILL make the coupler last longer, but the spacer and the coupler will crash at some point.

The I2K isolator is made of a material which is also slippery, self-lubricating, thermal insulating and extremely resistant to high temperatures.

A washer made in Teflon starts to (slowly) disintegrate at 200C, and much quicker so at 230+.

So, if you changed it reguarly it would help the Teflon coupler live much longer, yes. But the point for many is to avoid the "hot end rebuilds" in the first place:

Say, you are printing, and it is some time since you changed the coupler or the PTFE washer, then at some point the coupler will collapse somewhat and squeeze the filament going down.

Consequently you have hot end carbonization because you are not there within 90 secs to save the day, the printer tries to go on "forever", and you have a failed print.

We all have experienced how a print has failed for whatever reason JUST AT THE WRONG TIME.

This is why I, and many with me use a high tech wafer..

I agree with Didier, it seems nicer with a one piece coupler that lasts forever, and I am working on it now. But even all the combined brainpower at Ultimakers have not yet been able to find just the right material for it.

Like Didier is indicating: is your washer is not really the right shape you will have a leak, and swamp the whole hot end.

Meanwhile the I2K works well, 500hours/260C and counting.

[Anders Olsson 136]

I have probably printed 100 hours now with the I2K 1.5 mm spacer now.

Before that, the PTFE spacer had about 250-300 hours of printing with the 1 mm Vespel washer.

It still works perfectly fine, but I have not taken the hotend apart to inspect the PTFE spacer lately.

I have been switching back and forth between ABS, PLA, Flexible FPE, XT and Bridge Nylon and it seems to work well with all of them.

For cleaning the hotend, I use Bridge nylon which I pull at 135 C. It has worked fine so far.

At some point I will hack the firmware to go for Polycarbonate at about 300 C, but I have had plenty of other things that were higher on the priority list lately.

The design principle for the washer is to keep it thin enough to stay hot, so the plastic in contact with it is molten, but thick enough to get the temperature of the PTFE down below degradation levels.

A spacer completely made of I2K / Vespel / Polyimide will be very expensive and will most likely not work with PLA, since PLA gets very sticky when half molten to a rubbery state.

 

[conz 0]

The time is near that I have to think about the teflon replacement. I have only printed with PLA (incl. woodfill and polymaker PLA) for many hours now.

I don't like the requirement of expendable materials other than the filament. And I have read different impressions about the new teflon part with glass by ultimaker. (more friction)

I'm a little bit confused about all my current options for the UM2.

Is there some overview what alternatives are available for the UM2? With tests for the different hotend solutions?

Some users here seem to have some good experiences with "all metal hotends", but mostly on UM1. And I like the idea of different nozzle sizes.

Do you have some preferences for hotends for UM2 and some links what I have to change on the UM2 for the alternatives?