Mendel parts wanted, Midlands, UK

Hi there,

I've been looking to make a Reprap for a year or so, but not started yet.
The Mendel parts page lists the Reprapped parts (http://objects.reprap.org/wiki/Mendel_materials_procurement#Reprapped_parts) as a non-sourcable component, so, here I am.

If anyone near me (Coventry) has a working Reprap, and can knock out a set or Mendel parts, I can collect.
Can make a day of it, if you're a bit further afield.

Once it's working, I'll try to replace them for someone who wants a set. So keep an eye on this if you're after a set of Mendel parts.

Thanks

Is it normal for someone to print off a new set of parts when they get a Reprap built?
That's my plan, as soon as I'm sure it's going to print useable parts.

If so, they've got 2 sets, and can sell the other set on.

Ian

I thought it was by tradition that you would print off atleast 2 more sets when you finished your Mendal.

Andros1200 Wrote:
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> I thought it was by tradition that you would print
> off atleast 2 more sets when you finished your
> Mendal.

That's the promise that is rarely delivered upon.

60-80 hours is a lot of printing to "give away"

120-160 hours are not going to be given away.

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repraplogphase.blogspot.com

Hmm, I thought it might be like that.

As to the 80 hours to print a set off, how about a partial set? List what you aren't offering, and we can get someone else part-set could complete it.
If so, I'm up for that instead.

IF I ever get started, I'd be tuning the thing using the next set. It's not wasted time if there's a point to it. A box of spares is handy, and a full set can be impvoved upon, once complete.

On top of all that, isn't it better to recoup some of the set-up costs by selling on a set of parts?

Is anyone up for renting their spare set out? I'm up for that, if no-one wants to sell a set.

I have an auction that is still going on for 4 days.
[cgi.ebay.de]

I must agree with spacexula here. Multiple days
of day&night printing including the inevitable bad print,
technical problem and failing equipment under constant supervision
are nothing I would do for free.

As for partial sets, I am offering some design-challanges
[www.thingiverse.com]
and am trying to get other people to do the same.
The first to design the requested object can choose
(among other options) 10 mendel parts to be made.
This is ment to not offer currency and the price shall
be worth a few hours or a day of supervising a print.
Something that everybody can afford to get that one object
designed one cannot or does not have the time to design.

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spacexula Wrote:
-------------------------------------------------------
> Andros1200 Wrote:
> --------------------------------------------------
> -----
> > I thought it was by tradition that you would
> print
> > off atleast 2 more sets when you finished your
> > Mendal.
>
> That's the promise that is rarely delivered upon.
>
> 60-80 hours is a lot of printing to "give away"
>
> 120-160 hours are not going to be given away.

I'm not going to give away 60-80 hours of MY time. But I would probably be willing to give away that much of MY MACHINE's time. Especially after the first few weeks of playing around with it.

I think that once nophead's auto-ejecting vacuum held kapton bed design (or something similar) is proven and people invest in it, the cost of parts will go down dramatically.

This is because printed parts have three costs:
plastic (negligible for us, considerable for commercial printers.)
machine time (more than plastic, but still not much)
operator time (expensive)

Right now, with the finicky nature of reprap machines, operator time on a set of mendel parts is huge - like you said, 60-80 hours. Obviously, much of that time isn't actually doing anything, but is rather waiting on the machine. But the operator still has to be available in case something goes wrong, and has to be there to start the next part.

(derail)

Of course, to get truly unattended operation will also require more safeties, but that's fairly straightforward. Off the top of my head:
Max endstops
Emergency stop button
Head Crash sensor (stress sensor on head mount)
Filament ran out sensor
Extruder jam sensor (a wheel pressed against the filament above the motor?)
Backup heat sensors for each heater
Smoke detector
Power fail restart procedure (eject partial part, restart queue automatically, etc)
Excessive skip detection (if re-zeroing after a part indicates that there was an unexpected amount of skipping, don't start a new part)

I think that covers most of the failure modes I've seen reported in the forums. And it's only eight pins or so, so a single added "safety arduino" would probably be able to handle them. All this is getting a bit ahead of ourselves, of course. Not much point in speculation until the bed auto-eject is proven.

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I'm building it with Baling Wire

You forgot the most important safety of them all:

An optical encoder to detect skipped steps and
thus run the steppers as servos.
This also detects the head running into anything
and the extruder skipping and makes a machine
MUCH more reliable.

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* homeprototype free 3d design repository
* Blog
* Google+

jgilmore Wrote:
> Of course, to get truly unattended operation will
> also require more safeties, but that's fairly
> straightforward. Off the top of my head:
> Max endstops
> Emergency stop button
> Head Crash sensor (stress sensor on head mount)
> Filament ran out sensor
> Extruder jam sensor (a wheel pressed against the
> filament above the motor?)
> Backup heat sensors for each heater
> Smoke detector
> Power fail restart procedure (eject partial part,
> restart queue automatically, etc)
> Excessive skip detection (if re-zeroing after a
> part indicates that there was an unexpected amount
> of skipping, don't start a new part)


RepRap is not trying to replace industrial printers. IF you design a reprap with all the options you just listed, guess what you can have? A 3-10k desktop printer, and all the advantages of the RepRap are canceled out.

RepRap has not achieved their "Model T" printer yet. I think Mendel might be the Model T prototype. Remember what Adrian Bower and Vik have said from the beginning they want this to be for, developing countries.

The real problem is that with modern design tools we are all trying to dream the Model T prototype into a Bugatti Veyron.

To me the Holy Grail of RepRap would be a cheap, reliable, open source, easy to construct RP machine.

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repraplogphase.blogspot.com