Where to get extruder plastic parts from?

I have my name on the list for the machined parts a member here is making but I see no where to buy the extruder plastic parts from. Anyone have a link to who is selling them or anyone care to print me a set for a reasonable price? BTW BitsforBytes is not taking orders.

Assuming that you're here in the US, here are the files for a laser-cut version of the extruder...

[www.ponoko.com]

I am sure that if you called the ponoko people they'd give you a decent price for cutting the parts for you on their laser cutter machine.

Those are different plastic parts than the ones you are getting the machined bits for. You want the MK II extruder plastic bits. AFAIK no one is making those anymore. You have to get someone to print you a set.

Demented

Demented Chihuahua Wrote:
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> Those are different plastic parts than the ones
> you are getting the machined bits for. You want
> the MK II extruder plastic bits. AFAIK no one is
> making those anymore. You have to get someone to
> print you a set.
>
> Demented

Ah! You need to talk to Wade Boortz about that, then.

Yes, I'm slowly working on building a second RepRap, but I just realized I should be able to fit all the Mk2 extruder parts on the bed in a single build; that would be a convenient package to produce in a hurry; a one click manufacturing job (ignoring the hours of setup work, which only has to be done once). I just sent a set to Mike Ellery yesterday scrounged up from extra parts I'd made, but it would be simpler at this point to produce a lot of extruders, vs a lot of Darwins, which requires a lot more effort, tweaking and thinking on my part.

I actually bought a lasercut extruder as a backup, but I've never been able to get it to work as reliably as the old Mk 2 extruder, so I'm thinking I'll just keep making more of those Mk 2's. They're ugly, but they do work when you get them set up right! I've extruded almost 5 lbs of ABS through my extruder; I just had to replace the brass bearings after the first 4 lbs. I have an idea about how to improve that as well, but I have to do more testing.

I'll keep you posted, I'm Skeinforging the parts with my latest parameters at the moment; in a few hours I might be able to start a build. I'm still tweaking parameters to increase the quality, but my latest parts aren't half bad. I'll post some photos tomorrow if all goes well.

BTW, you can make a simple brass nozzle with just a hand drill; but a machined one will be much nicer. The screw drive is a bit tougher, but still doable. My hand drill's chuck is noticeably off center though, perhaps I should take up Brian on the offer of some machined parts!

Wade Bortz

What about the cast parts? I seem to remember reading a thread on here about cast extruder parts when I first got interested in reprap. Anyone have a mold I could borrow for a few weeks?

There's probably a good market for extruder parts, since they're used on all flavors of machine. Everyone needs at least one and a spare's not a bad thing to have. Probably even a good demand for built-and-tested extruders.

There is a member in the for sell section that is selling the machined extruder parts for a little over $30 plus shipping. I added my name to the list for a set of them so I have the mechanical parts covered. All I need is the plastic parts that make up the rest of the extruder. Would you mind printing a set of extruder parts Wade?

Working on it at the moment, my extruder is in it's warmup cycle for the first part in the series.

Unfortunately, I've also got a list as long as my arm of people that want parts, and most of them want an entire machine. How to choose? I still owe the RepRap community one more set of cheap parts, but I can't afford to keep producing them for beer indefinitely; I have to eat and pay rent as well, and it is still fairly time consuming to produce these parts. That first set took a month of concentrated effort, although much of that time was spent repairing things. That effort, of course, is going to decrease with every improvement that the community makes to the RepRap project.

Anyway, what's it worth to you, what do you think is a fair price? I suppose this is the sort of question that Ebay was designed to answer.

Well, with luck I'll have some pictures to post tomorrow of a set of extruder parts.

Wade

I have no idea what they would be worth. How much plastic goes into a set? Whats the time to print them? What would you feel as a fair price for the parts. I do not want to low ball you with an offer.

Wade Wrote:
-------------------------------------------------------

> through my extruder; I just had to replace the
> brass bearings after the first 4 lbs. I have an
> idea about how to improve that as well, but I have
> to do more testing.

What about using boston bronze? It would cost a little more; but, it should last longer as it is oil impregnated.

> off center though, perhaps I should take up Brian
> on the offer of some machined parts!

Just let me know!

Regards,

Brian

Hi Wade

Could you let me have a copy your skeinforge preferences when you have done the final tweaks.

---

Regards

Ian

Ok Brian, you're on! I'll trade a set of Mk2 printed extruder parts for a set of machined extruder parts, minus the flexible drive cable. My first cable didn't last 10 hours. The parts I'm offering are, from top to bottom:

-old Mk2 style direct drive motor mount
-Nophead's drive screw coupler
-standard screw holder
-standard polymer holder
-clamp

I need to look at the dimensions again, depending on the length of your drive screw, I might need to add some reprapped spacers between the motor mount and the screw holder. What's the overall length of your drive screw? Of course, a stack of washers would work too.

Actually, I could use two sets if you've got lots. I've got lots of plastic.

And SCphotog, I thought about pricing a lot. My first response was "One Miiilllion Dooolllaaarrrs!!!!" , but on second though, how about $20? That would make it worth my while, and if I can keep my Reprap running 24/7, at that rate it would almost pay for the dingy basement corner of a printshop that I rent to run it in. Note: at the moment, RepRaps do not run 24/7, no matter how hard you try. I've already given away two extruders pretty cheap, so I figure I can charge a bit more for these now. If that's too much, don't worry about it, I'll keep on doing what I've been doing.

Bearings - I believe the problem is my drive screw has a sloped shoulder on the bearing surface, which is bumpy and has a bit of thread left on it; it's essentially a crappy drill bit, and it slowly drills though my brass bearings over the course of a few weeks of extruding. My new bearings are going quickly, as evidenced by the amount of brass shavings coming out of the extruder, so a new screw with a smoother shoulder, or a new design is in order.

Onward!

Wade

Beware there may be compatibilty problems between the plastic and metal parts. My screw holder is for an M5 drive shaft but I think the latest is M6. The bearings I use are 10x6 with 3mm hole but I have seen other sizes mentioned.

---

[www.hydraraptor.blogspot.com]

Good point Nophead, the coupler I printed works with a M5 nut on the end of the drive screw, and my drive screw is M5. It should be fairly straightforward to rebuild it for an M6 nut, and it looks like Brian is using M6 for the drive screw, so I'll see if I can can edit the stl tomorrow. I've been having a hell of a time trying to get CoCreate running here, my ISP seems to filter out their license server for unknowable reasons, but I did get another cad package running.

Ian, here's my Skeinforge preferences. It would be nice to have a repository somewhere for these kinds of settings, but it's 5 am now, will have to do that later. FYI, my extruder has a 0.8mm thread pitch, and a 0.6 mm nozzle, but I generally stretch the filament to 0.5 mm to help span gaps and get a bit more resolution. I set the speed of the filament in RPM, using the M108S30.6 command (not the exact speed), which translates to 30.6 rpm on the drive screw, which you'd multiply by the thread pitch and the filament area to get plastic flow rate.

Wade

Edit - I forgot to mention, I don't think I'm anywhere near having a set of "final tweaks" for Skeinforge, things are still changing fairly rapidly. If I can get Chris's new Gcode interpeter running, that will change things yet again. But these parameters are working at the moment.

Edited 1 time(s). Last edit at 12/11/2008 05:14AM by Wade Bortz.

Wade Wrote:
-------------------------------------------------------
> Anyway, what's it worth to you, what do you think
> is a fair price? I suppose this is the sort of
> question that Ebay was designed to answer.
>
> Wade

EBay is an EXCELLENT idea! By auctioning you can determine a reasonable market value for the parts and as more people make parts and offer them for auction the prices will automatically come down. I would set the opening bid based on material costs.

Hello,

Wade, it's a deal! I'll send you 2 sets minus the cables. PM me with your address.

I am using the instructions from [reprap.org] for the dimensions for all the parts.

* The drive screw is M6 and is 70mm long.
* The bearings are 6mm dia. and 11mm long.
* The nozzle is going to have a 0.4mm hole. (Actually, it is going to 1/64" as I couldn't find metric drill bits of that size. 1/64" is 0.01562...which is 0.039675mm.) You should see how tiny these drill bits are!
* The goal is to keep the tolerance +-0.1mm (+-0.004) on the diameters as I can't get metric brass rod so I have to turn them down. So far, the bearings are about +-0.002 on the diameter.

Regards,

Brian

Ok, deal! Unfortunately, I got a little ahead of myself last night - started counting STL's before they hatched.

The Darwin STL files all have different X,Y and Z offsets, and sometimes rotations, and I've managed to edit them all to a right side up version, but most still have odd offsets. I spent a good bit of time last night editing the full extruder build gcodes to avoid head collisions, and still keep everything within my build area.

Then I loaded the wrong file.

Oops. Adrian's host software would make this part of the job a lot easier; I need to try that again. Using Skeinforge and ReplicatorG gives me good print quality, but I don't get much a preview of what's going to happen. I've been using EMC's Axis software to check the toolpaths, but that doesn't help when I load the wrong file.

So, now I've got a pile of half burned plastic, and a jammed Y axis, and no new extruder parts. I keep my motor currents set as low as possible, which seemed to prevent any serious damage, luckily. Guess I should be more careful editing Gcodes at 3 am. Ah well, will try again with some edited Gcodes tonight.

Hey, just noticed a couple things on that documentation page; I'll post them in Brian's machined parts post.

Wade

Wade $20 is perfect. I wont be able to get the $$ to you until after Christmas tho. I leave for my Mothers home tomorrow and will not be back until the 28th. So no rush on my parts. These use the direct drive screw right?

Yeah, no worries, I'm having some trouble with my manufacturing line anyway.

In Alibre there is an option for .STL files. Its under Tools> Options> File Types> Configure File Types. Just change the file type to STL

JohnWasser Wrote:
-------------------------------------------------------
> EBay is an EXCELLENT idea! By auctioning you can
> determine a reasonable market value for the parts
> and as more people make parts and offer them for
> auction the prices will automatically come down. I
> would set the opening bid based on material costs.

I second the motion.

--clint

Would you folk like RepRap to run an ebay-style auction/marketplace? I know ebay will work for some of this, but not necessarily for jobshop stuff.

Also, can anyone recommend some good free software to do so on a linux server? I spent the evening looking around online without much luck. phpauction comes up a fair bit, but I think they may just be very good at search engine self-placement.

reifsnyderb Wrote:
-------------------------------------------------------
> What about using boston bronze? It would cost a
> little more; but, it should last longer as it is
> oil impregnated.


Brian, et al,

I haven't heard it called "boston bronze" before; I've heard it called "Oilite" bronze" or "oil impregnated bronze -- finely powdered bronze, sintered (porus) solid, voids filled with oil. Like you, it struck me as a good material to try for bushings -- cheaper than ball/roller bearings, and easily machined to size.

It looks to me that it's cheaper to buy tubular pieces and cut them, than buying rod stock and machining it. I have some on order from mscdirect.com -- I was expecting them yestderday, sigh :-(
(These are made by Boston gear; is that where the term boston bronze comes from?)


MSC part number, 0645304 $0.57/each
Description: 1/8 X 1/4 X 1/4 BRONZE SLEEVE BRGS

-- Larry

Larry,

I don't know where the term "Boston Bronze" came from. Maybe it is a local term or something. But, I have seen it used successfully in long-term applications...and wear pretty well.

The closest stock, I found, would cost something like $3 for 2 or 3 inches and would have to be machined to size. After machining, the individual bearing cost could easily be over $10. Especially since they are half-bearings.

Those bronze-sleeve bearings, you mention, may work pretty good...once a steel drive screw were made to fit.

I am thinking that there should be some sort of thrust bearing, as well. That would keep the screw from cutting into the bearings. It appears that the main thrust should be only in one direction, so maybe a thrust bearing should be located up near the motor? The down-side of this would be a more complicated drive screw, of course.

Once I get some extruder parts, then I might get a better idea as to how to proceed.

Regards,

Brian



Larry_Pfeffer Wrote:
>
> Brian, et al,
>
> I haven't heard it called "boston bronze" before;
> I've heard it called "Oilite" bronze" or "oil
> impregnated bronze -- finely powdered bronze,
> sintered (porus) solid, voids filled with oil.
> Like you, it struck me as a good material to try
> for bushings -- cheaper than ball/roller bearings,
> and easily machined to size.
>
> It looks to me that it's cheaper to buy tubular
> pieces and cut them, than buying rod stock and
> machining it. I have some on order from
> mscdirect.com -- I was expecting them yestderday,
> sigh :-(
> (These are made by Boston gear; is that where the
> term boston bronze comes from?)
>
>
> MSC part number, 0645304 $0.57/each
> Description: 1/8 X 1/4 X 1/4 BRONZE SLEEVE BRGS
>
> -- Larry

reifsnyderb Wrote:


> Those bronze-sleeve bearings, you mention, may
> work pretty good...once a steel drive screw were
> made to fit.
>
> I am thinking that there should be some sort of
> thrust bearing, as well. That would keep the
> screw from cutting into the bearings. It appears
> that the main thrust should be only in one
> direction, so maybe a thrust bearing should be
> located up near the motor?


Brian,

I was pleasantly surprised to find the finished bearings cost less than the raw stock. I suspect this is an economy of scale issue -- one that helps us, for a change.

Re thrust bearing:
I believe some people are reversing the screw drive to avoid drip (esp. those without a valve.) So, a thrust bearing should ideally support axial thrusts both toward and away from the motor. My hope is that the shoulders at the ends of the turned-down sections of the drive screw might serve (well enough) bearing against the ends of the bushings. What do you think about that notion?

-- Larry
(eagerly awaiting receipt of materials and tools; tomorrow pm, I hope)

The reversal would only release pressure so it would not generate significant thrust in the opposite direction. Also the time spent reversing is so small compared to forwards any wear would be insignificant.

I am going to investigate using a deep groove ball bearing at the top end for thrust and two small ones acting as rollers under a land at the end of the drive screw. It needs a re-design of the plastic parts but they are the easy bit to produce.

---

[www.hydraraptor.blogspot.com]

Larry,

>
> Brian,
>
> I was pleasantly surprised to find the finished
> bearings cost less than the raw stock. I suspect
> this is an economy of scale issue -- one that
> helps us, for a change.

Yeah, any use of off-the-shelf components will be cheaper and allow more people to build the machine.

> Re thrust bearing:
> I believe some people are reversing the screw
> drive to avoid drip (esp. those without a valve.)
> So, a thrust bearing should ideally support axial
> thrusts both toward and away from the motor. My
> hope is that the shoulders at the ends of the
> turned-down sections of the drive screw might
> serve (well enough) bearing against the ends of
> the bushings. What do you think about that
> notion?

My guess is that turning down the drive screw wouldn't provide enough of a shoulder to prevent excessive wear. If the screw threads, or remains of the screw threads, contact the bearing, the time-to-failure will increase. Either a shoulder would need added to the drive-screw (i.e. a threaded disk located somewhere below the motor coupling and secured in place somehow...maybe a setscrew?) or maybe nophead's idea will work.

It also occured to me that maybe the whole drivescrew idea needs to be looked at. My MIG welder uses two rollers to feed the wire. Maybe that idea could be copied and we could have a knurled roller, connected to a motor, pushing against a grooved roller feeding the wire in between both rollers?

> -- Larry
> (eagerly awaiting receipt of materials and tools;
> tomorrow pm, I hope)

Regards,

Brian

Edited 1 time(s). Last edit at 12/14/2008 08:34PM by reifsnyderb.

The knurled roller Idea is pretty good. I would worry about flattening the filament though. I will model a few designs in Alibre later today and post them.

I've been thinking along these lines for a while - using fairly hard rubber rollers to save deforming the filament. If the filament ran in a groove in both rollers it would be compressed reasonably evenly. Using ball bearings (maybe needle roller on one side to allow automatic alignment) would allow the pressure to be high to avoid slipping without requiring excessive power to operate.