Extruder

[SPEEDRE]

Has anyone tried to scratch build an extruder ?. How difficult could it get ?. How bad could it get ?. Too technical for amateurs ?

[fritzgutten]

I've built an extruder of my own design. It was time consuming. By far the most tedious parts are drilling a .5 mm hole and making my own heater coil. Luckily there are ways around both. There are simpler designs available using off the shelf components. Definately doable with a bit of effort

[jolafson]

Hey SPEEDRE, John here. We sell just the hot-ends from our machines, if you're interested. Also, we sell the nozzles and resistors/thermistors seperately too. Our nozzles come in .020" dia. hole size, 5/16-24 threads if you wanted to make your own heater block and use our nozzle. SeeMeCNC is our website.

Ok, done with the advertising now. Don't be afraid to try it. It's not that hard at all. If you have a CNC, you've learned more than most starting out in the 3D printer world! The only big thing to consider is:

1.75mm or 3mm filament

They are both semi-easily sourced. The reprap crowd uses both extensively. 1.75 is easier to use they say. It takes less force to extrude, and the smaller diameter is easier to control extrusion rate.

Other than that, the next big challenge is driving it down into the hot nozzle. We use a teflon tube inside a PEEK plastic barrel, dual drive rollers that have a light knurl, an aluminum upper heater block, for fast thermal transfer, a steel lower clamp section for heat retention at the nozzle, two 6.8 Ohm resistors that actually do the heating, a 100K Ohm thermistor for measuring the temps, and a $10 relay board that takes the signal from the thermistor and sends the current to the resistors. It works great.

Here's some pics and links to take a look at what we do
Jpeg of our entire extruder

Top view of ours

Looking inside the extruder This one shows the PEEK tube, but inside that yellowish tube is where the teflon "liner" goes.

Hot-End This is a good shot of our hot-end. From bottom to top, the brass nozzle, steel clamp, aluminum body, PEEK barrel, PEEK barrel mount, then the rest is the mounting for our x axis carriage.



Take a look at those, and give it a shot.

Also, as we are an open source project, you're free to download the .stl cad files and build one from our prints too! But, for $38.00, we'll ship you one tomorrow! (Ok, last shameless advertising, I promise)


Have a good one
John Oly

[SPEEDRE]

I don't understand something. Does the extruder on the site include, the heater for the filament, and a connection for the temperature regulator. It may be clear I am not up to speed on the terms used in 3d building, but am I right to say all I have to do is add a stepper motor to have a fully functioning extruder head.

[jolafson]

SPEEDRE

The extruder kit comes with the two heating resistors and the thermistor used to heat and monitor the heats. You can add a stepper motor for $25 more to it, so you get that too. The only thing you will have to do is provide the stepper control for the motor, and heating circuit control. We use inexpensive velleman MK138 thermostat kits. If you use that kit, all you need to do is swap the resistor #5 for a 10-20K Ohm resistor, and the thermistor included in our kit will allow the velleman kit to control the temps up to about 450-475 F range. The heater is "standalone" meaning you turn it on, wait for it to get hot, and when it's hot, run your Gcode!

Hope that helps clear it up,

Thanks again,
John

[EL34]

Hi John,
I am assembling an extruder from scratch to mount on and test on my CNC machine
If I like the test results I will built a stand alone printer.

Glad I found your post because I was wondering how to control the temperature without spending big bucks on one of the fancy temp control boards that have a display. Display would be nice, but not needed for my test rig.

velleman MK138 thermostat kits - I googled this and found the web site. thanks for that info.

I noticed you change out the thermistor to change the temp range
Are you using a 100K thermistor?

thanks for any help

[Fastest1]

I have built, combined and or changed the parts from 3-4 designs on the market. Presently I am running a stainless tube from a Makerbot or Makergear product of some kind (it was laying in my parts bin) I bored a piece of PTFE rod as the liner to assist the feed. I use no PEEK. I removed the finned barrel of the Arcol's V4 and screwed the stainless tube directly into the heater block. It is much more rigid, not near as delicate. Has less parts and extrudes beautifully. I can put my hand on the stepper at anytime in a multi hour print and temps are reasonable. I can leave my hand on it. Also the way the SS tube clamps to my stepper, the aluminum piece is never warm. I have a fan on there to cool the tube but have had to redirect the flow because it gives the heating block difficulty in achieving higher temps. Btw, insulate the heater block itself if at all possible, just the block. If you can cool above and below it, your printing will be great.

I went ahead and showed the parts of the Arcol's on the last picture. I ended up only using the stainless tube screwed directly into the nozzle (same thread) then screwed that assembly into the heater block.
In the picture with the hot end having the insulated tube around the barrel. This set up had the most stable heat production and I will likely use a liquid insulation product to coat the heat block only. I have seen the product on Nopheads site somewhere. When running the Arcol's, I had used the SS tube to mount it to my stepper. The multiple junctions created too many issues in feeding. Arcol's didn't intend it to be used that way and his design would have fed well most likely had I not modded it. It was an accidental realization that I could eliminate most of the parts. I have run 230C with no issues for hours now. When I ran anything with PEEK, it would get flimsy at temp. I hated that. I still can't figure out why anyone used it. The SS works great.

[Fastest1]

The last picture as you can see has 4 parts, though they are partially assembled. I only used 2 of those 4. Also Arcol's used a jet of some kind to hold the small PTFE liner he had right at the entry. Nice design, I just had a different idea and mount.

[Fastest1]

I shot a little video to show the results.

[EL34]

Nice vid, thanks

Just got my spool of 1.75mm PLA and now I have to figure out the tube situation down to the nozzle

Are you running 1.75mm ABS?
I am guessing you are not running PLA cause you have a heater bed?

So your stainless tube has a teflon sleeve inside, is that correct?
Do you know the OD and ID of the tube?

All the tubes I have been looking at are combinations of teflon and what not and it seemed to me it could be done more simply like yours

[Fastest1]

I am running 3mm ABS, 230C, .5mm nozzle diameter, .2mm layer heights at the moment. I took a piece of PTFE rod and drilled out the center to accomodate the filament. Then I turned the outside down to fit in the SS tube, I left a small collar (OD) at the nozzle end that is clamped between the nozzle and the tube when they are screwed together that eliminates the PTFE moving. Simple and a total of 4 parts. The tube, PTFE insert, nozzle and heater block. If I would turn it off I could disassemble it easy enough to show you but I am having too much fun.

[EL34]

I have access to all that stuff to make the delivery tube and a lathe but I don't quite have a clear picture of your internal pfte tube yet

So it fits inside the SS tube and you have a hole down the center that is 3MM or maybe a tad larger than 3mm so it does not bind easily?

Then where the pfte tube meets the nozzle you have a flange

Is is like what I have drawn here?
thanks for your help