Nozzle clogs - jams and other fun with PLA

[Sandtoe]

I thought I should post some information about the fun I had swithing from ABS to PLA. So here goes.

ME - new to 3D printing only had the Rostock Max for less than a month. So please ignore all the newbie mistakes.
So here I am printing away on my 20th or so ABS print. I was a thing-a-verse paste extruder body. Set it and went to bed. Next morning it looks awful. From the bottom to 1/3 the wayit it looks great and then from there to the top it is all raggetty and holey. I walk away and go to work.

Later - I heat up the hot end and run some filament in 10mm increments. It isn't flowing well. Spitting some and not smooth. Does not even look like the full thickness it should be. This must be what a clogged nozzle is. So I let the hot end cool to remove the nozzle. Big mistake as I will show you. I removed the nozzle and it didn't remove easily- I sort of had a bad feeling but here is what happened.

Nozzle removed while cold

The PTFE 2mm tube came along with it. This means my only perfectly sized tube is now smaller than it should be. Well don't have any PTFE sitting around but lets clear the clogg first. I found two ways online. Acetone and torch. I choose acetone as it was later at night and seemed less an issue. (here is a good link to torch method http://www.youtube.com/watch?v=6bTfl35zlHE ) I left it soaking in Acetone for 48 hours. When I took it out it was a soft guncky consistency. I use a drill bit to push it through the nozzle and used a popsickle stick cut down to fit ot scrap any other stuff out. I also had on hand a small resistor where the wire was a perfect fit to push thorough the nozzle opening.

Used a small drill bit to push the Acetone soaked ABS thorugh the nozzle

Outside of nozzle clog cleared

Inside of Nozzle cleared

OK all good right - time to switch from ABS to PLA. Oh, wait that PTFE thing I twisted off. Well lets look at the PTFE tubes. Need to remove them from the hot end. I push on them and no go. I heat the hotend and push. No go. I heat up high to 240 and find a metal file with a round 2mm size. I push hard and they come out. ( maybe next time I will remove the hot end from plateform.) Below is what I see. That doesn't look right.

melted PTFE or just deformed. Not sure

Try to make do and it does not work well. You can see belwo where some ABS squeezed through the too shor PTFE liner.

Inside the Hotend - that is some ABS from trying to use to small a PTFE tube

Ok, so off buy some PTFE.. I found some here (http://www.ebay.com/usr/sidewinderinc?_ ... 1439.l2754) tis is 2mm ID and 4mm OD and 3.2 ID and 5.2 OD. Why did I buy these couple of reasons . I would like to try 3mm filament so this would work for that and I found that I could not put the PTFE back into the Hot End. I could do it when it was new as I took it apart and looked at it. I did find tis out when looking at my PEEK.

PEEK connection

One side is 1/4 and the other is 7/32. Since 7/32 is less than 6mm ( 5.3 mm )that may explain why I can't put it back in very well. I noticed my original PTFE was split so I will use the same method.

Original PTFE from SeeMeCNC for nozzle

The PTFE arrives
I put the 2mm PTFE into the Nozzle and then screw it into the Hotend to find the length I need. ( can't use the old one as I broke it. ) then I subtract the end of the PTC fitting ( about an 1/8th inch) and that is my 2mm size. I that a length equal to the 2mm of the 3.2 mm. I slice one side so it can split open. It is a smaller Inside Diamter than the outsdie diameter of the 2mm ID PTFE. It looks like below.

PFTE liners measured

Executive decision. I will drill out the PEEK so that it is all about 6mm well it will be 1/4 as that is the drill bit I have.
Now the PTFE tube slides inside and works well.

I load the ABS and heat the hot end up to arround 220 degrees. I am doing to becasue I am going to push by hand the PLA thorugh the hotend and lower the temperature about 5 degrees at a time to determine when the resistance starts to get dificult. I know then that I should use the above temp .

So I think I should be using 215 but that sound really high. Well let me try. Two pieces of blue tape and a 60 degree bed. Let's make the cube. Hmm, it isn't sticking. Google says don't use a heated bed when using blue tape ( I tink it canme from a makerbot sight). I try and it works. My ABS cube comes out great.
off to bed.

Next day I decide to print a flat arduino case with sides. It doesn't print well. I appears the filiment quite extruding somewhere in the middle. struders fault it is that the filiment will not move thorugh the hotend. In fact it is stuck and I can't pull it out. I do get it out after a really good tug and break it off. Now I need to remove the PTFE tub again. SMarter this time I keep the heat on and the nozzle removes easily. The PTFE slides right out. but it looks like below. I don't bother removing the PLA as I know have more PTFE. I setup the hotend again.
Trying again. Why did this happen. Well the heat must be too high near the top of the hot end. I will do the hand extrusion test an see if it can go lower. - Actually it can I find 195 will work. An start the print. But now it will not stick to the Blue tape. - OK- I remove the tape and heat the bed to 75 degrees. It sticks now and the print is working. - Ah shoot- not again . Yes the exact same thing happens as it did above. A ways into the print the filament jams in the hotend .

Running too hot with PLA?

You can se from above that the PLA is getting to soft and twisting and not making it thruogh the PTFE and into the hot end. This is happening inside the bowden tube PTC fitting between the bowden tube end the and the PTFE hot end tube. Ok, hit the max for pictures.

So it does not seem I can lower the temperature below 195 forthe PLA. But if I can then that may be a solution to the PLA softening in the PTC fitting. Oh, I suppose I should ad it run the FAN on Full using a shroud and the stock 25x25 FAN.

So for now I have switched out the PLA for ABS. But I really want to use it as I want to try some lost wax casting with it. I have tried a lot of things and a lot of setting today and that me be part of the problem too. I really thought I had the issue licked by lowering the temp but even at 160 the PTC fitting is hot. I know that some say PLA gets soft when left in a car so I am thinking that the PTC fitting is just geting too hot. I could run a 2mm bowden tube all the way into the hot end but I would need a way to stop the tube moving upon retraction. Maybe I can find a 4mm fitting that would attach on the HOT end outside threads. Or I need another fan. It is vey interesting as this does not happen with ABS when running at a much higher temperature.
Ok, that was my Sunday. How was yours?

[DavidF]

When I built my rostock, I put the Spacer washer under the mount to lower the print head so I could grab the aluminium portion with pliers and be able to remove the nozzle hot.

[Sandtoe]

I ordered a new PEEK from SeeMeCNC. I thought I should have one since I print close to 230 a lot. But My new peek is different from my old PEEK. It appears to be only big enough for a 4mm tube at the top of it and there seems to be some room for a 5-6mm tube around it at what I think is the bottom conection. Not sure of the set up for this. But perhaps this will fix my PLA woes from above.
I assume the first picture will connect to top of hot end (Bowden side) and next pic will connect to lower end (Nozzle Side). Does anyone have experience with this PEEK. I didn't see anything in the forums per say. Thank you.

Top view assumed

peektop.jpg (21.25 KiB) Viewed 3866 times

Bottom View assumed

Previous PEEK Setup ( like this pic from a previous post)

http://forum.seemecnc.com/viewtopic.php?t=2254&p=16132

I had this setup where to PTFE tubes ran through the PEEK.