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Why does PTFE isolator for 1.75mm have an input diameter of 8mm???

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Hi.

I'm using 1.75mm filaments with 4mm outer diameter bowden tube and noticed that the PTFE isolator in the printhead has an input diameter of 8mm!

The exit diameter is 2mm, which is OK.

Looking at the drawings of the vendors of such isolators, they all seem to be the same 8mm input diameter for the 1.75mm filament version, while the 3mm filament version has an input diameter of about 6mm, which is about right for a 6mm outer diameter, 4mm inner diameter bowden tube that is usually used for 3mm filaments.

Since the bowden tube usually used for 1.75 mm filaments has a 4mm outer diameter (2mm inner), I really don't understand why the 1.75mm version of the PTFE isolator has an input diameter of 8mm!??

Since I use a 4mm OD bowden tube, I have initially fitted the end of it with a 6mm OD section which I happened to also have. However, this is still does not match the 8mm input diameter of the PTFE isolator, and therefore results in problems, e.g. when inserting new material, since the hole of the bowden tube and the 2mm hole of the PTFE isolator do not normally align even when I use the 6mm OD section.

I cannot imagine that I must use an 8mm OD, 6mm ID bowden tube for my 1.75mm filament... Or that I must fit a section of 8mm tube to my 6mm tube end for my 4mm tube (like russian dolls).

Any ideas as to why such a travesty in the PTFE isolator design for 1.75mm filaments?

Edited by Guest

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@umagi you mean like this?

 

Probably yes. I was looking on some well-known Chinese site for 1.75mm PTFE couplers for UM2, and they all seem to have that input diameter of 8mm, which makes no sense to me.

I will have a look at the TFT coupler from 3dSolex as Dim3nsioneer suggested.

Edited by Guest

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Hi Dim3nsioneer,

 

Can you please tell us what PTFE coupler you are talking about? There is no 1.75mm PTFE coupler from Ultimaker

 

You're right. I was looking at a well-known Chinese site...

 

the TFT coupler from 3dSolex should have a similar bore/opening as the 2.85mm version.

 

Yes, but have you seen the price ? 16 Euros for this thing? They must be kidding?

Apparently, they are out of stock, "waiting from material from the US", so are they making these parts themselves? If so, I could try to make my own part, since I can have access to a lathe. However, I'm not sure how well PTFE is worked on like that.

Update: I found this Youtube link that shows some (big) PTFE seal being made from a lathe, so I may give it a try myself, if I can find some PTFE rod somewhere...

 

Edited by Guest

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Yes, but have you seen the price ? 16 Euros for this thing? They must be kidding?

Apparently, they are out of stock, "waiting from material from the US", so are they making these parts themselves?

 

As far as I know 3dSolex let them produce in a place in Norway or Sweden; @swordriff may want to correct me.

The 3dSolex couplers are made of TFT which is not a standard PTFE material but has improved heat resistivity. And manufacturing the couplers is about tolerances. They are very important as you want no gap between Bowden tube and TFT coupler as well as between TFT coupler and stainless steel coupler. Quality has its price as it has its costs. But also its benefits.

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The convertion of Um2 to "native" 1.75mm filament faces several obstacles.

That being said, you can actually print 1.75 filament on the existing setup, only it will not work with flexible material, and retraction settings can be increased by 1-2mm, to offset the sideways move in the oversized Bowden tube ID (inner diameter).

You may need possibly to adjust the feeder, but this is not strictly necessary.

Another obstacle is that there is such a big gap between the thinner filament and the block which has a ca 3.2mm lead in for the filament, goes for teflon as well.

This results in more hydraulic back pressure, which can easily be demonstrated by performing an Atomic "press",; the first of two main actions in Atomic Method namely pressing down filament by hand into hot hotend. You will see fluid filament move upwards inside the teflon.

This leads to conclusion;

All though 1.75 printing is certainly (!) possible in a standard setup, there are great benefits in making the following changes to the configurtion, in order of importance:

1) Teflon ID adapted to 1.75mm filament

2) Bowden tube adapted to 1.75mm filament

3) I2K insulator adapted to....

4) Block ...

5) ... and least important to able to print 1.75 on UM2/Um2+: Nozzles adapted to 1.75.

Now, since standard teflons have a Bowden receptacle fit for PTFE 6,3mm OD,  and the quickest way to print 1,75 well is to supply a Teflon which will work with the stock Bowden (for ca 3mm).  

When the Chinese manufacture this item, they not always take tolerances so seriously, so wether the receptacle is 6.4 or 8mm is maybe not so important to them.

If it is really too big, you risk hitting the "top roof" of the teflon when inserting the filament (especially 1.75) since it will follow the wall of the Bowden and not hit the entry hole of the Teflon.

The fix to all this is a bowden with ID adapted to 1,75,  A Teflon which receives the Bowden well and, a modification to the chamfer of the lead in to the Teflon to help guide the filament in...

The nozzles are not imporant for 1.75, only Atomic Method according to eipc instructions at www.3dverkstan.se ( in english) will not work well.

The Teflon from 3dSolex is 5-10 times more expensive (raw material) and is made in the USA compared to Teflon from China which is made in... China!

There is a similar difference between Teflon as there is between cars. Some cars have top speed 165km/h, some (eh.. actually just a few) 420km/h.

BOWDEN TUBES.

It is very difficult to manufacture the Bowdens with an OD 6.x and ID 2.x, since the resulting stiffness hinders the bending of the tube.  

I am currently looking into having two tubes made, one with ID 4.1, and another with OD 4.0 and then put one inside the other. It may solve the problem..

The Teflon (TFT) from 3dSolex, when purchased together with an I2k  carries a 6month guarantee, print as much as you want up until 295C. The Guarantee does not cover physical "schlitashe" inside the TFT  which will happen with CF, Bronzefill etc.

Edited by Guest

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@umagi you mean like this?

img.thumb.png.f4bdf93e14819d708c508fc1c701f1e3.png

 

OMG the tube which works here cannot be made in Teflon or any other slippery and strong material in existence.. The OD would need to be 7-8mm and at the same time ID 2mm, else it is really tough to make the flament enter without being a jongleur and having 3 hands ( yes you could probably partially disassemble the head each time you change filament and make it work)

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Maybe it's different on um2 but Inhave been printing 7months now with a bowden 6-2mm without issues on umo. The only mod extra I need (apart of all the other stuff) it's the taller bowden clip that it's on youmagine designed by anders. And on umo (I need to test um2 how this works) I reduce the retractions to 3.2mm instead of the standard 4.5mm for faster retracts and less preassure build up.

Also I use other bowden tube that so far it's alive and working for 9months now that uses the standard 6-3 ultimaker bowden with a 3-2 ptfe glued with special ptfe glue. Not even the baddest atomic has take it out. The ptfe glue it's a special two parts glue that costs 3-4€ on amazon made in poland.

The curved ptfe seems like a good idea to help fit it but I must say that fells weird to what I'm used to.

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I also sourced 6-4.5 bowden to insert a 2-4mm but the force needed to push it in when you reach the first 20cm it's too high to my taste, and the advantage of using um 6-3,15 bowden with a 2-3 it's that it leaves room for the glue to not generate preassure on the inner bowden.

Edited by Guest

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The Teflon from 3dSolex is 5-10 times more expensive (raw material) and is made in the USA compared to Teflon from China which is made in... China!

 

Hmm... PTFE is just a polymer of fluor and carbon ... not sure any difference in polymerization process justifies a 5 to 10 times increase in price...

As for TFT, I can't seem to find any info on that? What does it stand for?

Edited by Guest

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Please print with a Chinese PTFE at 260C, then try TFM (ULtimaker) or TFT (3dSolex) and you will se the difference.

A car is just a box with an engine and 4 wheels. How can they justify the difference in price between a KIA and a BMW. Materials, tolerance, measurements. Example, the better Teflon piece has less chance of filament crash when entering the new filament. It can also take 255C indefinately.

This is worth something, if not it would be like a writer publishes a book, and then sell it for just printing price, 1-3 dollars / book.

There is a constant development of new products ( eh... books too!) .. this cost money too!

The cheapest way to use teflon is to buy from Aliexpress and then wait for prints to fail, but dont buy the 1,75 one as the filament will not enter.

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Hi swordriff,

It is obvious that I am a beginner isn't it? ^^.

 

A car is just a box with an engine and 4 wheels. How can they justify the difference in price between a KIA and a BMW.

 

Well the difference is that we are talking about raw materials here, the result of a simple (but what do I know, I always hated my chemistry classes)  polymerization process to give a single, base material (well, if you don't count the carbon and fluor of course).

What you are talking about are complex finished products.

I agree that dimensional tolerances etc... can be different for a worked piece of PTFE, but I don't see how much different the raw material can be, which is the result of an automatic chaining process of the C2F4 monomers. Impurities maybe? Small impurities can have a great effect on material properties of course, cfr. semiconductor doping for instance.

In any case, I was just wondering. As you suggested, I'll have to indeed experiment!

Thanks for your valuable info.

Edited by Guest

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Hey! In this business, we are all beginners, wait and see!

If you try a cheap teflon and print at 260, you see what happens!

There is a large number of additives and procedures which make a difference in the raw material. The cheap ones start disintegrating at ca 200C, slowly at first, releasing the famous "bird killing fumes". This weakens the teflon`s physical integrity and it will start to sag until it suddenly grips the filament, not unlike a heroinist who took too much.

While it is sagging into the filament and we do not know exactly that Thats what is happening, we start blaming Ultimaker, temp sensor, heater, filament, nozzle and block.

Could be the bowden tube too, often overlooked...

So better to buy a good one.

The expensive ones are start evaporating at 260C.

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