donmilne

Not in the sense you probably mean. Some 3D design software allows you to import STL, but it will usually be imported as a locked shape, not something you can do complex edits on - scaling is the most you could expect. Basically, the conversion from model to STL is one way.

Sorry, but I do believe that the stock feeder contains several fundamental design errors, the most important of which IMHO are :- [*]very fiddly to adjust tension - you really can't see what's happening because the filament is mostly hidden [*]guaranteed to accumulate debris inside with no easy way to clean. [*]no way to partially open it for cleaning - the same four screws that hold on the cover also hold the feeder motor. [*]once the thing is apart you need three or four hands to put it back together. IMHO, these are serious errors. I don't really buy the safety argument - it's a small knurled wheel moving quite slowly. However you could always fit an external cover, maybe held in place with velcro.

Though it occurs to me that by "jam" you may be referring to grinding and underextrusion in general. Those can happen for lots of reasons, regardless of the feeder, but Robert's feeder doesn't make the problem worse.

Actually, the stock feeder is broke, which is why Robert's redesign is so popular. Also, the only way Robert's feeder can jam is if you wind up the spring tension too high. OTOH the ability to more easily adjust tension is another of its strengths. There's a good discussion of the various designs in the mods forum.

"Uploading"? Do you mean that it won't load? Is there are error message? Can you make the STL available for download from somewhere? Perhaps one of us could tell you what's wrong with it.

Can you expand on this problem and your solution?

Actually, it's very possible to create an STL from almost anything - there's nothing in STL that enforces watertight models, it's just a list of unrelated 3D polygons - hence the market for STL repair tools. It's the model that has to be watertight, not the output format. And obviously, it's easier to create watertight models if the modelling software is designed to do that.

If you already have the stock feeder in bits I'd say it's too late to be nervous! - after all, what would be stopping you putting the stock feeder back if Robert's feeder didn't work out?

The filament can also get hung up as it enters the hot end, for similar reasons. I find it a good idea to put a bit of a point on the filament instead of cutting it square. It never gets caught then.

Please note that CAD tools are not necessarily best for 3D printing. You need something designed for solid modelling, that enforces rules for solid, watertight shapes.

Looks right to me, assuming you have the Bowden collet and clip somewhere handy. I suggest that you print out Robert's feeder as soon as possible. Jams are impossible, it's easier to clean, and you can service it without the feeder stepper falling off the back.

You've accidentally included the smiley in the URL, but when that is fixed... looks good to me!

I can't debate with you about warranty, spare parts pricing etc - that's between you and UM support. The deformation looks quite uniform. Did you ever take the hotend apart, in particular did you remove the nozzle? I'm just wondering if the part has been squeezed vertically: pure PTFE does have a tendency to creep under load.

I had a look with an STL viewer I wrote myself. All the polygon surface normals in this STL are set to zero (this is supposed to indicate the outside direction). I guess that causes problems in some software. Also, the object has a detail / corrugated texture on many surfaces. I don't know if this was intended or not. The texture has a vertical grain which might make it awkward (and noisy!) to print. I only looked at the outward appearance: I didn't check to see whether the shape was legal, i.e. a single closed surface, no intersecting solids.

The UM2 no longer ships with the old pure PTFE part, so first time buyers of new printers needn't worry. The glass filled PTFE part is now standard, and as Didier says can also be bought in the store for those early adopters who missed out. Yes, it is irritating, but design defects do happen. There is an interesting discussion going on here about how to improve this part further. Btw, do you have a picture of your PTFE coupler showing the deformation? I've used my printer a similar amount as you, and I recently replaced the PTFE coupler with the glass filled one, but in fact I found that the original pure PTFE coupler was completely undamaged. I tend to use something between 210C and 220C.

What is "normal temperature usage"? I'm not challenging you, I just want precision / clarity.

There are several castles nearby: e.g. Cowie Castle and Fetteresso Castle, but perhaps the most famous is Dunnottar Castle. There is no crashed satellite in the grounds (that I've heard about). Apart from appearing in CoD, perhaps Stonehaven's bigger claim to fame is that life on dry land seems to have started there. http://en.wikipedia.org/wiki/Pneumodesmus

Yes, I really live in Stonehaven, Scotland, and it is a real place. http://en.wikipedia.org/wiki/Stonehaven I've heard of CoD, but I know nothing about it. I'm afraid I got bored with video games long ago.

I seem to remember someone else once posting on these forums that the number is not an estimate. Cura knows exactly how many steps of the feeder stepper motor that it's going to do, so underextrusion aside, the "estimate" should be spot on. So it isn't an estimate, it's an input!

Yes, there are a lot of crappy 3D printers around, and crappy software too. But, presumably you have a specific printer and software in mind? While I would certainly recommend that you get you own 3D printer for early experiments, there are also commercial printing services which can support higher quality and better materials for late prototypes.

Hmm. I'm dubious. I don't like the loss of idler bearings. I'd want to wait until this thing acquires a decent track record, not just be swayed by a nice presentation.

What size (capacity) of SD card is it? I had similar problems with an 8GB card (which is therefore actually SDHC), no problems at all with a 2GB card. I expect the card also needs to be formatted with the FAT filesystem: not NTFS, exFAT or anything else.

I understand that intuition - symmetry is always appealing. But, putting drive cogs on both sides of the filament means you can't cope with variable filament diameters, and filament changes are cumbersome. I recommend that you read this entire thread, because the complete list of design requirements includes some quite subtle points.

My vision was basically just a doubling up of Robert's feeder: two drive cogs on the same side of the filament, opposed by one or two (not sure) spring loaded idler bearings on an arm that can be moved aside to change filaments. The two drive cogs would themselves be driven by... something, a worm drive perhaps. Somehow they need to be driven in the same direction. These are just vague thoughts, I've haven't had time to think it through.

I would have thought you need a washer rather than an O-ring. With an O-ring thing will be a rib of PLA which if allowed to cool will prevent you from changing filaments.