Where can I buy makerbot extruder tips?

I've been waiting for the makerbot tip to become avail for a short while, and am losing my patience. Anyone know where I can buy them if not from makerbot? Thanks.

MakerBot Industries has them custom manufactured, so unless you want to take their drawings and have someone else manufacture them for you, you're out of luck. May I suggest MakerGear for hot ends though, I use one of theirs and they are extremely reliable.

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I find the number of options in MakerGear's shop to be overwhelming. Can you give an example list of items I would need to get from them?

The best place to get answers is on the MakerGear IRC channel.

Rick

[www.makergear.com]
Pick one of the $75 SuperPacks, with whatever nozzle size you want. I would recommend 0.4mm for starters. Then pick a wooden mounting piece that corresponds with whatever extruder type you are using. Rick is extremely helpful and will answer any questions you have, you can contact him via his IRC channel or the Google group, both of which are listed in the left column on the site.

Edit: looks like he beat me to it!

Edited 1 time(s). Last edit at 03/16/2011 02:47PM by NewPerfection.

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Talked to some very helpful folks in IRC last night and they cleared up a lot of questions I had. I even got the inside scoop on a cool new groovemount that will be on offer soon
NewPerfection, why do you suggest starting with a 0.4 nozzle? I was thinking of getting the 0.25 nozzle. Shouldn't that allow me to get better resolution, or am I over simplifying here?

unicoder Wrote:
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> NewPerfection, why do you suggest starting with a
> 0.4 nozzle? I was thinking of getting the 0.25
> nozzle. Shouldn't that allow me to get better
> resolution, or am I over simplifying here?

A 0.25 nozzle will work fine, it's just that the smaller the nozzle you get the longer your prints will take. I use a 0.35mm nozzle with 0.25mm layer height and I get great resolution without it taking forever to make a part. A 0.25mm nozzle has half the area of a 0.35mm nozzle, and so will take twice as long to print an object, depending on your settings. If you aren't worried about speed, then by all means get a 0.25mm nozzle.

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What's a groovemount?

BTW...does anyone know how much torque the step extruder motor has?

I'm going to venture an educated guess here. A Groovemount (tm) is an insulator that also function as a mounting system for your hotend.

As for the motor, I'd guess that depends on which motor you get. I'm getting this Nema 17 motor, which lists a holding torque of 5.5Kg.cm

unicoder Wrote:
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> As for the motor, I'd guess that depends on which
> motor you get. I'm getting this Nema 17 motor,
> which lists a holding torque of 5.5Kg.cm

That's plenty of torque. My extruder motor has about 5 kg*cm, and it's incredibly strong. I'd guess that anything over 3 kg*cm would do fine.

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What's 5kg/cm converted to oz/in?

from google calculator:

5 (kg * cm) = 69.436933 ounce inches

Actually, assuming you're limited by the head speed of your Cartesian robot, the volumetric flow of plastic through your extruder varies with the square of the nozzle diameter (or your extruded filament diameter, whichever you want to measure). So, cutting the nozzle size in half means your print times go up by a factor of 4, as long as you're still printing about the same amount of plastic per part.

I switched out a 0.5 mm nozzle with a 0.35 mm nozzle recently, and a large tray of Mendel parts took 15 hours to complete, as opposed to 7.5 hours with the 0.35 mm nozzle. I got the 0.35 mm nozzle from MakerGear, btw, and it's worked quite well.

Smaller nozzles also require higher pressure to print at high speeds; you're more likely to have extruder problems with a smaller nozzle.

Wade

Wade Wrote:
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> Actually, assuming you're limited by the head
> speed of your Cartesian robot, the volumetric flow
> of plastic through your extruder varies with the
> square of the nozzle diameter (or your extruded
> filament diameter, whichever you want to measure).

I'm under the impression that nophead said it didn't really matter. (I think. Could be wrong) The volume of extruded plastic is what matters, and with higher pressure you can force just as much plastic through a smaller nozzle as a larger one. The main effects are that you can do smaller layers, and have a higher nozzle pressure.

Something about the degree to which you can squash a filament being limited for some reason. Thinner layers don't work well with larger nozzles.

And bridges don't work if you're squishing the filament to make it wider, of course.

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I'm building it with Baling Wire

It sounds like there is still a lot of differing opinions regarding this part of the printer. Wade, what would you recommend for a newbie? 0.5mm or 0.35mm? Of course, my first order of business after building my prusa mendel will be to print a set of replacement parts. Will that take ages with 0.35mm?

jgilmore Wrote:

> I'm under the impression that nophead said it
> didn't really matter. (I think. Could be wrong)
> The volume of extruded plastic is what matters,
> and with higher pressure you can force just as
> much plastic through a smaller nozzle as a larger
> one. The main effects are that you can do smaller
> layers, and have a higher nozzle pressure.
>
> Something about the degree to which you can squash
> a filament being limited for some reason. Thinner
> layers don't work well with larger nozzles.
>
> And bridges don't work if you're squishing the
> filament to make it wider, of course.

If you run a 0.25 mm nozzle at 0.5 mm output filament width, it will be just as fast as a 0.5 mm nozzle running at 0.5 mm output filament width, the pressures will just be a lot higher. Although I think Nophead found that the reasonable limit was lower than that, but you'll have to search his blog for the details.

I was just pointing out that the build times for 0.25 mm output filament, regardless of nozzle size, will be 4 times as long as a 0.5 mm nozzle - it varies with the area of the extruded filament, not the diameter - it's a squared function, not a direct one.

My Mendel can print a full set of Mendel parts in about 48 hours at 0.5 mm with my settings; that will jump to 96 hours at 0.35, and almost 200 hours at 0.25 mm. Printing a set of Prusa parts will be much faster of course, because they use less plastic.

Finer nozzles should be fine (hah!), just watch out that you don't break your hot end - the older extruder designs had trouble pushing the filament even with 0.6 mm nozzles, but that was due to a lack of grip, low torque, and poor hot end designs. I wouldn't recommend using the finest available nozzle for your first try, but do whatever works for you.

Wade

Although one can theoretically get any filament width (within reason) from a single nozzle by simply altering the head travel rate, I have found that if you try make the filament too thin by moving faster there comes a point where the filament is kinda 'pulsed' or results in thicker blobs with thinner sections in between... if that explanation makes sence.

Yes you can only stretch it so much before it starts to snap. The other limit is you can't go bigger than the die swell diameter because it needs to be stretched a little to pull it straight. If you try to compress filament it wiggles rather than forming a straight line. So the range of diameters from a single nozzle and a particular plastic is about from the die swell diameter down to about half that.

Within that range of diameters you can trade horizontal and vertical resolution by changing the aspect ratio. If you you go below 1.5:1 the object starts to get weak due to small contact area between the filaments. There doesn't seem to be much limit going the other way, certainly 3:1 works fine but you have to remember to increase the number of solid layers accordingly. For example 3 is fine for 1.5:1 but 3:1 would need about 6.

The maximum flow rate you can get through a small nozzle depends on the viscosity relative to the shear strength. It much higher for PLA than it is for ABS because PLA is both less viscous and harder.

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Quote
Nophead
The maximum flow rate you can get through a small nozzle depends on the viscosity relative to the shear strength. It much higher for PLA than it is for ABS because PLA is both less viscous and harder.

Does the PTFE lining in Adrian's new hot end help with PLA?

Yes it will reduce the force required to push the cold plastic plug at the transition zone. For large nozzles and low speeds that force dominates, but for tiny nozzles and high flow rates the nozzle pressure will become significant.

The other liming aspect is that die swell increases with pressure, so it gets bigger with smaller nozzles and higher speeds. So if you halve the nozzle diameter and halve the extruded diameter then you are stretching the filament more. As stated above there is a limit to how much you can stretch it before it snaps, so the minimum filament diameter will be more than half the minimum for the bigger nozzle. I.e. a law of diminishing returns.

Edited 1 time(s). Last edit at 03/21/2011 09:53AM by nophead.

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