Machined Extruder Parts

LOL! Told ya!

Edited 1 time(s). Last edit at 12/10/2008 04:42PM by Forrest Higgs.

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Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison

FireCrack, SCphotog, jeffpark_: I have each of you down for 1 kit.




Tonight, I made 14 PTFE holders out of a 2' piece of 5/8" PTFE. Tomorrow night I will either work on the nozzles or the M6 threaded parts. I need to think about whether it will work better to make the nozzles on the South Bend 13" lathe or the mini-lathe. The mini-lathe worked great for making the bearings.

Regards,

Brian

Forrest Higgs Wrote:
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> LOL! Told ya!



That you did!

I'll soon have to order more raw materials, for the second batch of kits, and it will be a few more days until I have the first batch of kits completed.

Brian, I just had a look at the Extruder 1.1 documentation page, and it looks like they left out the part about the half round bearings. Those 11 by 6 mm brass bearings are for the gear drive, which I haven't been using with my Mk 2 extruder. The part that wears out on my machine is the two half round bearings that fit into the screw holder. Mine are shorter than 11 mm, because the flats on the drive screw are only 10 mm long (I believe, I haven't checked, just going by the documentation).

Also, a 0.4 mm hole is going to be very small; so far I've been using 0.6 mm most of the time. 0.4 would be great for resolution if it works, but it is going to slow down the build times a fair bit. Make sure the length of the 0.4 mm hole is as short as possible, otherwise we won't be able to extrude much of anything. If it's a problem, we can always drill it out a bit.

Also, what shape are you making the nozzle? The flat acorn nut style tends to accumulate a lot of plastic; the BfB nozzle I got was around 0.5 mm and conical, cut at roughly 45 deg from the nozzle axis, and it made very clean parts, when I could get the rest of the extruder to extrude.

Looks like I need to change a few things on my side before we can make a matching set; I'll change Nophead's coupler to 6mm, and make sure that a 6mm drive screw will fit (I'm using 5 mm at the moment), and add some spacers between the motor mount and the screw holder to fit the length of the drive screw.

Wade

Brian hold off on turning my drive screw. Wade is going to be making me some Mk 2 extruder parts and I may need the Drive screw be direct drive instead of cable drive.

Wade,

I found the half round bearings and they are on the improvements page....so I haven't been making them and don't have the stock for them at the present time.

I am going to make the nozzle as per the Extruder 1.1 documentation page. However, I can reduce the length of the nozzle tip as you suggest.

If you are using the direct drive screw, as it appears that you are, the direct drive screw is 96mm. While the cable drive screw is 70mm. Right now, I am planning on machining the kits with the cable drive screw. I can make yours the direct-drive screw without any problem...and it's easier to make.

Regards,

Brian




Wade Wrote:
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> Brian, I just had a look at the Extruder 1.1
> documentation page, and it looks like they left
> out the part about the half round bearings. Those
> 11 by 6 mm brass bearings are for the gear drive,
> which I haven't been using with my Mk 2 extruder.
> The part that wears out on my machine is the two
> half round bearings that fit into the screw
> holder. Mine are shorter than 11 mm, because the
> flats on the drive screw are only 10 mm long (I
> believe, I haven't checked, just going by the
> documentation).
>
> Also, a 0.4 mm hole is going to be very small; so
> far I've been using 0.6 mm most of the time. 0.4
> would be great for resolution if it works, but it
> is going to slow down the build times a fair bit.
> Make sure the length of the 0.4 mm hole is as
> short as possible, otherwise we won't be able to
> extrude much of anything. If it's a problem, we
> can always drill it out a bit.
>
> Also, what shape are you making the nozzle? The
> flat acorn nut style tends to accumulate a lot of
> plastic; the BfB nozzle I got was around 0.5 mm
> and conical, cut at roughly 45 deg from the nozzle
> axis, and it made very clean parts, when I could
> get the rest of the extruder to extrude.
>
> Looks like I need to change a few things on my
> side before we can make a matching set; I'll
> change Nophead's coupler to 6mm, and make sure
> that a 6mm drive screw will fit (I'm using 5 mm at
> the moment), and add some spacers between the
> motor mount and the screw holder to fit the length
> of the drive screw.
>
> Wade

SCphotog Wrote:
-------------------------------------------------------
> Brian hold off on turning my drive screw. Wade is
> going to be making me some Mk 2 extruder parts and
> I may need the Drive screw be direct drive instead
> of cable drive.


Will do.

Brian

Hello,

It appears that there may be an issue where the kits should probably be made using the direct-drive system instead of the cable-drive system and there are some half-bearings required that were listed on the improvements web page. I PM'd Wade to obtain more dimensions, on the half-bearings, as I know they are 10mm long with a 3mm hole; but, I don't have the outer dimensions. Once I have the outer dimensions, I'll order the stock so that I can run a batch.

Unless there are any objections, I'll make the kits direct-drive by default instead of cable drive. I'll have to PM everyone who ordered kits, this evening, and verify that the change is ok. Sorry about the change; but, I would rather have everybody get the right thing the first time.

I also ordered more PTFE and M6 threaded rod.

Regards,

Brian

Sorry, as expected, there are a lot of versions of the extruder out there already, and that generates some confusion.

I'm using the original drive screw, 70 mm, and the extruders I'm building are the Mk2 versions, which are even simpler than the direct drive version (which has no cable, but does have a reduction gear).

What I'm building is essentially Nophead's extruder, I've been calling it the Mk2, details are here:

[objects.reprap.org]

This extruder has worked very well for Nophead as well as me; we've both printed out complete Darwins with it. Take note though; we both use closed loop extruder control, which I think is pretty important. I use Zach's magnetic encoder board, available from the RRRF.org.

So, the 70 mm drive shaft should work just fine, you just don't need the flexible cable, or even the hole drilled in the end of the shaft. You will need the half round bearings no matter what you build though.

The spacers are needed because the 70 mm drive shaft is about 5 mm longer than Nophead's, I just used some plast bits, and you can see some details of my setup here:

[picasaweb.google.com]

Brian, I'll measure the holes in the latest STL files when I get back to the lab, but for now I think 6mm outer diameter should be fine. It's not going to be a perfect fit, as the holes on the screw holder are square, not round, but that's what the polymorph is for.

Wade

The reason the half bearings have gone from the latest design is that the latest pump housing has plastic bearings built in. I haven't tried it but as brass does not last long enough I can't imagine plastic lasting any longer. I am currently trying phosphor bronze 10mm outside diameter, 6mm wide with a 3mm hole, but then I am using an older design of drive screw with square sided bearing lands.

I have stuck with 5mm shaft because 6mm has a bigger pitch so will need more torque. The latest design has gears, so has more torque, but doesn't go fast enough for me. I don't know what will happen with a 6mm shaft and direct drive.

It is all a bit of a mess. A wiki is not very good for version controlling things. Also the official design moves on based on Adrian and Ed's experiences but they have never built a complete RepRap. As far as I know only Vik, Wade and myself have run an extruder long enough to make a complete set of parts. I think we all used the older design with direct drive, 5mm drive screw and metal bearings.

Edited 1 time(s). Last edit at 12/11/2008 03:21PM by nophead.

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[www.hydraraptor.blogspot.com]

Where is the wear occurring? Is it happening at the ends of the bearings or making the hole out-of-round?

If it is occurring at the ends of the bearings, maybe a thrust bearing is needed?

Regards,

Brian



nophead Wrote:
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> The reason the half bearings have gone from the
> latest design is that the latest pump housing has
> plastic bearings built in. I haven't tried it but
> as brass does not last long enough I can't imagine
> plastic lasting any longer. I am currently trying
> phosphor bronze 10mm outside diameter, 6mm wide
> with a 3mm hole, but then I am using an older
> design of drive screw with square sided bearing
> lands.

In light of the current problem with parts specifications, I'll be making the heater barrels tonight as that is something that won't be affected by the drive screw and bearing issues.

Regards,

Brian

It wears both ways but failure occurs when the the drive screw sinks too deep into the housing so that the pump halves close and no longer grip the filament.

I am going to try some small deep groove ball bearings next.

Pictures here: [hydraraptor.blogspot.com]

Edited 1 time(s). Last edit at 12/11/2008 04:05PM by nophead.

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[www.hydraraptor.blogspot.com]

Hello,

Tonight, I have 19 heater barrels...minus the notch. I'll notch them all tomorrow evening on my milling machine.

I think Wade and I have the parts straightened out. I'll order what is needed tomorrow.

Regards,

Brian

Hello,

M5 nuts have been ordered as well as M5 steel rod for the drive screw and brass rod for the bearing material.

Regards,

Brian

All of the heater barrels are done! I have a stock of 19 of them. I notched them out, on my milling machine, and cleaned up the threads this evening.

Tonight, I am also working on the production of the nozzles. I have 2 lathes set up for this task and I am working on optimizing there production. So far, I have made 2 nozzles. The first nozzle is probably quite usable; but, I don't think I am going to sell it as the orifice is slightly off center. The other nozzle looks real good.

I'll start making the nozzles either tomorrow evening or Sunday evening as I don't have the materials for the bearings or drive screws yet.

Regards,

Brian

Hello,

I ran off a batch of 26 nozzles with a 0.4mm orifice, this evening. These nozzles are a little smaller in diameter (0.275) than the 8mm specified; but, that should be better as there will be less brass to heat up.

Regards,

Brian

Hello,

I got the M5 nuts, M5 threaded rod, and brass stock for the half-bearings in today.

So, I went downstairs, to make the fixtures for them, and ended up ruining a fixture and busting a tap.

So, I called it quits for the evening and had a glass of wine.

I'll get back to it tomorrow evening.

Regards,

Brian

Bummer. No sweat, slick. Sit back, take your time, relax...and hurry up every chance you get.

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- Rick

A chicken has a head the size of a walnut. Yet, even it has the sense to come in out of the rain.

Tonight, I finished the collet, for the half bearings, and made 30 bearings to mill in half. Tomorrow evening, I plan on making another 30, or so, bearings and start milling them in half.

Regards,

Brian

I now have a small pile of half-bearings. I plan on making some more half-bearings tonight as I have 2 machines set up to make them and want to ensure that I have enough for some time.

Regards,

Brian

Hey, here's an update from the RepRap side of producing extruders.

Theoretically, I should be able to crank out a set of MkII extruder parts in about 11 hours. Reality begs to differ, unfortunately. I made a couple errors in the original gcode mashup, (I have to quit trying to do 3 dimensional coordinate calculations in my head), which resulted in several thousand head collisions overnight last weekend. I fixed everything up, and then made another mistake, and so on; I'll blog some of the gory details in the Builder's Blog, but at this point I'm almost there. Here's a photo of the parts slapped together:



Note - I've got about 5 poly holders, but no good screw holders yet, so this guy has two poly holders, so I'm not quite ready to ship it. I've got 3 more screw holders building right now though, and the first one looks good to go.

Brian, this one has your name on it, we'll see how many more I can make.

Wade

A couple notes about those builds:

-they're lumpy. Yup.

-There's a lot of warping on the clamp. Warping seems to be getting worse for me at the moment, might be related to the lab cooling off with the winter temps. Luckily the warping is on the underside, so it doesn't matter much. The extruder that built these is warped more than that, but it's been working fine, despite a few thousand head collisions.

-Nuts, bolts, and GM3's aren't included. You'll want to add washers too. I do have some PTFE if people need it.

Wade

Wade Wrote:
-------------------------------------------------------
>
> A couple notes about those builds: Warping
> seems to be getting worse for me at the moment,
> might be related to the lab cooling off with the
> winter temps.
>
Get a hair drier.

[blog.reprap.org]

Heat lamp will get you the 60 degrees that Adrian specifies, too.

[www.3dreplicators.com]

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Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison

Hello,

Tonight, I finished making the half bearings and started tooling up the lathe for the drive screws. Though I wanted to start making the drive screws tonight, it looks like I will start tomorrow evening. I may have to experiment a little to find the best configuration to make a batch of drive screws efficiently.

Regards,

Brian

Wade Wrote:
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> Brian, this one has your name on it, we'll see how
> many more I can make.
>

Wake,

Great! I'll be looking forward to it. I plan on starting to ship the parts kits on Monday or Tuesday. Assuming that the weather is decent, of course, so I can get to the post office.

Regards,

Brian

Hello,

I completed the first drive screw, this evening. I have 19 other drive screws with one journal and only need to machine the other journal in order to have enough for 20 kits.

Once these are finished, I'll contact everyone who is interested in order to see if they are still interested and arrange payment and shipping.

I am still planning on shipping the first kits either Monday or Tuesday, weather permitting. Any kits not shipped by Tuesday, will be shipped after Christmas as I will be away.

Regards,

Brian

Hello,

The first batch of parts is done.



Regards,

Brian

Very nice.

Brilliant! I've been wanting somebody to do what you've just done for over two years now.

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Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison