Margin of error? Or did i get ripped off?

Hello,

I bought the printed parts for a Mendel I2 on ebay about a month ago, and have been building it ever since - acquiring additional vitamins as i went along. I had a terrible time getting everything square, true, and parallel, but chalked that up to it being my first build. I'm not a complete fool when it comes to building things though, so i was a little surprised. I was also a bit disappointed with the quality of the print, but i wasn't 100% sure of what to expect as these are the only printed parts I've held in my hand.

Two things were causing me problems in particular. The motion along the Z axis, and the extruder. As you can see in the pictures, several of the large printed parts are way out of square. It looks as if each layer was printed shifted a few hundredths of a millimeter from the last layer. For instance, the base of the extruder shifts 1.54mm in just 38mm - roughly 2.5 degrees.

The problems with the Gregs Hinged / Accessible extruder with herring bone gears are the most obvious visually. The small gear has a ridge that runs along the circumference of the teeth, and there are serious infill gaps. the holes are not perpendicular to the rotation of the gears so there is a lot off wobble and hopping when turning. The X-ends being out of square are causing a slight bow / hour glass shape in the smooth rods, making motion choppy and tight.

I would have to assume that the smaller parts suffer from the same problems, but without completely dissembling i cant say for sure. Does the expression "don't blame the tools, blame the carpenter" apply, or was i sold worthless parts? If the part are a problem, do you think it's time to get new ones, or is it possible to get decent prints with them?

Thanks!
--Steve

Erm, those blue parts, they are the ones you bought, or ones you have printed yourself ?
I don't quite understand.

If they are ones you've bought, I'm afraid it's not good news.

Those are parts that I bought.

I thought i was a 99% built and a few final adjustments away my first print, when i realized that I might not be the problem getting things to move smoothly.

--Steve

I hope you've not left feedback yet then. I'm afraid they are horrendous.

Which country are you in ? Odd question I know, but I am about to start printing a Mendel I2 on my Huxley.
(a Huxley is a mini mendel)

See if you can get your money back on those parts .... and ... If you have any spare vitamins for a Mendel, I could trade you some printed parts for vitamins, as I'm about to start sourcing vitamins anyway ;-)

Im in London (UK) btw

Edited 1 time(s). Last edit at 01/07/2014 05:10PM by DaveS.

Hi Steve, welcome to the forum!

Who did you buy them from? Might save someone else the same grief...

Obviously the parts were printed on a very poorly set up machine. I don't know if they are usable. Someone could always carve, force, and heat form some of those back into usable shape, then print better parts. It depends on the money vs time equation.

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Yvan

Singularity Machine

Those parts are just warped. The builder didn't have the proper headed bed or brims. But they are the right design. All you need is a better source, or to use PLA for the most part (excluding anything close to the extruder) because PLA does not warp as easily.

*just warped*
I don't think people should be selling warped parts.
A bit grainy on vertical walls maybe, but charging actual money for warped parts isn't really on, IMHO.

I've bought a few printed parts off ebay, and they have been mostly ok, not perfect. I had to ditch a few parts that were just unusable. The price wasn't really a giveaway, but I needed parts for a new extruder.

I'd say the ones you have got are sub-standard. You can cope with a bit of imperfection and bodging until you can print better parts yourself, but there still needs to be a basic level of quality to get you that far.

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Who did you buy them from?

If you can't get your money back....
Carefully warm them up to 10 to 20C below their glass transition temperature (experiment with the temperature).
Then clamp them against a master, and allow to cool.

Those are not 'just warped'. Those are clearly printed on a machine that is out of square. The extruder drive gear should also have infill between the teeth. You will have nothing but problems with those parts.

Hope you didn't spend much for those! I certainly would get a complete replacement from someone else, because if this if what was sent to you, even if they are willing to replace them, they won't be worth the hassle.

Get parts from someone that has 100% feedback rating and has sold alot of parts, not the ones with the cheapest price.

Edited 2 time(s). Last edit at 01/07/2014 07:38PM by Dirty Steve.

Thank you, everyone, for your responses. I bought these parts at the beginning of December, and wanted to be sure that what I received was sub-par before I contacted the seller. The seller listed them with a 14 day return policy, but hopefully he/she will see fit to give me full refund.

The seller is now listing the same bunch of parts again, so I'll be waiting for a quick response, and hopefully make sure someone else isn't burned. I've bought a lot of things on ebay before, including all of the vitamins for my future reprap, and i'm still optimistic.

I'll be sure to let everyone know how it goes.

It took all of 6 minutes to get a response from the seller offering a refund. Hopefully I'll actually get my money back

yeah it looks like they need to readjust the z axis, its off by a few degrees.

I would be more than embarrassed to sell something like that. It's just not ethical. Maybe it's a 12 old that just things they are good. (no offense to 12 year olds. At that age I was building my own RC cars and real dune buggies & trailers with my dad using drill press, lathe, welders, torches, grinders and more).

I have to say that so far the seller seems to be more than happy to resolve the situation. He first offered a full refund, and then offered to send me full set of new parts to show that the parts I received are not indicative of his product. I guess reprappers tend to be good people

Maybe he is reading the forum!

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Yvan

Singularity Machine