gixxer

Hi Schwimmy, If your just starting out 3D printing then I'd suggest PLA for most things. As long as the models aren't going to be kept in a hot car as PLA will start to loose its shape above 45-50C. ColorFabb do some nice Copper, Brass and Bronze fill PLA filaments for the awards which can be shined up using wire wool or other polishing methods with some work. http://colorfabb.com/special-filaments%C2%A0

OK.... I've done some calculations. First off I had anticipated that the angle of the taper would need to specifically chosen for our average filament diameter. This is not the case at all... and feel a little dull for not seeing this sooner :oops: . The angle of taper has no impact on the diameter at the contact point of the filament. Yes the filament will move up and down the taper as its diameter fluctuates which will in turn give different feed rates but not enough. The correction in feed rate for a drop in filament diameter from 3mm to 2.85mm would only be 1.6%, which is negligible (bugger all). I would really like someone else to run the numbers on this two confirm though, as I can almost see the bottom of my fourth glass of red! However all is not lost. I do still think that a v shaped block would provide better friction on the filament along with a profiled sprung bearing. There's only one way to test this theory though and that's get one machined unless I can find an off the shelf v groove to fit the drive. I know that the R&D team at Ultimaker have done a huge amount of work testing different profiles of wheels so before I go spending money I'd love to know if this approach has already been looked at. It is worth noting that without the twin taper setup fluctuations in the filament diameter would be magnified instead of marginally corrected by I assume the same 1.6%. However if the extra bit on the filament prevents slip the marginally amplified flow variation would go unnoticed. Its also worth noting that for real gains (assuming the v groove was better) the point at which the stepper motor skips / steps back would need to be modified, which I believe is done by increasing the supplied current but not sure if this is a firmware mod. Eagerly awaiting criticism :-P ..... constructive that is :mrgreen: .

To be more specific the bar peeling used a v shaped wheel with a groove in the base. I'm not to sure about info on these systems. I used to work for a company that produced titanium bar, the bar peel systems we used and most others we looked at employed the same feeder. The bit of a v style is supposed to deform the filament / bar less than opposing rolls. The taper means that the drive wheels don't need to be sprung which also means that it's much easier to transfer drive from master to slave wheels. I've not seen a feeder systems that compensates for deviations in filament diameter. That's not to say I'm 100% sure that this will but in theory it should.

Here is an idea I had for a feed mechanism. Please excuse the drawing I'm on hols with the family and only have the kids pens to work with The sketch shows two taper wheels one being the drive and the other driven by the gear at the base of the taper. The filament in orange is pressed into the taper by a profiled bearing that is sprung. The mechanism has two interesting benefits. 1. The bite provided by the two tapers should allow for much greater pushing force before slipping. (it's used on most feed systems for bar peeling where force and bit are critical) 2. Now this is the interesting bit. The taper means that a thicker filament moves out on the taper to a smaller diameter i.e feeds less. Thinner filament moves into the taper to a larger diameter i.e feeds more. Point two should provide a more consistent flow through the nozzle with no need to monitor filament diameter prior to the feeder to correct for inconsistent filament diameter. Now the angle of the taper is critical to the function of this system. I'm only at the idea stage so far and would really like to know what everyone thinks.

Interesting MendellS. Have you measured how much force is required to pull the filament through the wheels? So long as this is less than the force required to push the unstraightened filament this would work fine. Now replace the middle wheel with the drive wheel and spring load the other two and you have a feeder and straightener in one

E3D by the way do a very good pla called polymax enhanced for £27.50/750g. Not so cheap but it's very strong stuff!

Been using the pla from rs components for some time now, think it's £21 for 1kg. Haven't had any problems so far after about 5 spools. The abs is also pretty good. I've also tried e3d pla and abs and had good results. Think they sell at £12.50 for 750g. Avoid the verbatim filament from rs components though as I could only use about half the spool the rest snapped every 30mm as it unspoiled. I've not tried Faberdashery filament yet simple because it's not spooled. I have seen some printable spools for unspooled filament on thingivers and youmagine you may want to try though.

Ah.. I've not tried that before!

Why the 200% flow? Where you getting underextrusion? Assuming the increase in flow had no slip in the feeder this would indeed be 21.6mm3/s.

We'll done swordriff it's good to you looking after those buying anders blocks. And well done Mohissa! Great video.

It requires very little force to pull the wires out of the sensor. So last resort. You could try an m2 tap or reamer.

Quote:Sure about that, gr5? Does layerheight affect feeder speed? Did I miss something. Increase in layer hight = more material layer down = greater feeder speed.

Looks like to high temp/not enough fan. Try printing cooler and slower. If that's um pla, it's not the best.

Good find on the Tecasint. Looks like the 2061 would be the preferred one. Have you done much testing so far? Also do we know what the glass transaction temp of the standard is?

How's the custom block working Chris? I'm also very interested in the fan mount. I was thinking of trying that one out myself but was worried the radiated heat from the block would cause problems.

Welcome to the forum Fixer. When you get your machine I'd recommend you spend some time with the standard heater block first so you can get a good feel for printing. You'll have a good idea for how to tweak the settings for the custom one then. I've posted a drawing of my custom block a few pages back but I'd think it would be less hassle getting one of Anders block from Swordriff. @@@@@@ Please note that if you intend to machine my one the slot depth needs to be doubled @@@@@ All this talk of wine.... Time to open a bottle!

Thanks for adding the pic gr5

Makes perfect sense to me. You can add pillowing to the downside list also. Think this may be due to the more exposed E3D nozzle. Not really had a problem before. I tend to use simplify3d so just add a few more top layers. I've not had much of a problem with stringing so far but we'll see.

Gr5- A short time line so were all clear. 1250h printing with standard nozzle. Blue um filament needs 250C to close off top surfaces but will print walls OK down to about 230C. Other pla including other um colours close off top surfaces OK at about 230C. Calibrated temp prob inserted down the nozzle shows marked discrepancy between bots temp and probe temp. Don't understand why bit its a lot higher than it should be. There's images of the temp diff in my gallary (the forum doesn't want me to paste them here for some reason). Abs prints OK at 260C issues if temp refused. [gr edit - added picture:] Changed standard nozzle block for new standard block three days prior to fitting custom block. Chaged the isolator also (didn't have to as now deformation just some discolouration at the contact point). During the refit I had no option but to pull at the temp sensor as there was no metal cap protruding from the block which resulted in me pulling out the wires. So new temp sensor fitted (did not cross check the nozzle temp). Blue um pla still required 250C to close top surface. Only got about 20h printing with this block (fitted to ensure I had a good comparison for the custom block). Changed to custom block with 0.4mm E3D nozzle. Didn't change anything else. Blue um pla now closes top surfaces a good 30C lower and ABS prints today where done at 230C. I've tried some colourfabb pla today also and that was printed at 205C (would not have ever tried to go this low before, would have previously used 230C). Melt zone on the new block is 3.7mm longer than standard block.

I think we need to be cautious saying that these custom blocks would solve underextrusion problems at all without further testing. We also need to identify the differences between the custom block to the standard. The first key differences (that could affect extrusion rates) that I think we could put some numbers on are: Mass of block with 0.4mm nozzle tip in. Length of melt zone from the top of the block to the tip of the fully inserted nozzle tip (again using the same 0.4mm tip) The other variable would be internal nozzle geometry, easy for the E3D nozzle but I don't think there was much on the internals of the standard block in the open source file. I'll get the melt zone length for my block for you tomorrow but the weight will not be accurate as the block has been used. Do you think swordriff or Anders that you could take some measurements? I have an unused standard block in work that I'll measures up tomorrow also.

I don't think there was a partial clog as I changed to a new standard UM block just days before I fitted the custom specifically to try the problematic blue filament for the purpose of a good comparison. It was the same. Printing at 50mm/s required 250+ to close off top surfaces. The custom solved this. Could the 0.4 tip from E3D actually be a 0.45? This is a possibility. I ordered two of each size so I'll give the other 0.4mm a go on Monday.

Have you managed to strip the threads on the tips Anders or was the printable nozzle torque wrench part of the project from the start? Great work on that but the way.

That blue pla that came with the UM2 that's the stuff. I've not hat underextrusion with any other filament ABS,PLA, NYLON, XT, Copper fill or PET but that blue stiff is poor. I've not tried your printable nozzle torque wrench as yet but it's at the top of the list. I just used an adjustable to nip up the tips been very careful not to go to far. I was very surprised how much force I could put on the little M2 clamp that holds the sensor and heater in my block before I opened out the cut. Thought to would have stripped the thread. I had a small nut as plan B but didn't need it.

Dam did I weight all that on my phone! I need sleep!

Yes I to am looking forward to playing with the 0.25mm nozzle. Don't think it's going to be used that much by myself though. I'm mostly printing prototypes of our plant equipment and although it could be useful in some prints the print time would take forever. Longest print so far was 72h with the standard nozzle so I dread to think what that would have been at 0.25mm. I'd really love to show you some of these but as Robert says NDA's are a bitch.