Hardware store hot end

I'm new to 3D printing and am in the process of building a delta robot (Rostock) style printer modeled after the one Jonathan Keep made (http://www.keep-art.co.uk/Self_build.html) but with FDM capability instead of or in addition to the clay extrusion technique he uses. While I'm gathering parts and materials I decided to have a go at assembling a hot end from freely available hardware. The attached photo shows a first attempt fabricated from lamp parts and aluminum and teflon washers (the threaded shafts shown are hollow). Still to do are to grind the cap nut to a cone and drill a nozzle hole, drill and tap the top cap for a push connector for a Bowden extruder tube, and drill vent holes in the 2 brass couplers. Also to be added are an aluminum block heater just above the cap nut at the bottom and a shroud for the cooling fan. Cost for the parts used so far not including the push connector and fan is about $12.
Before I get farther with this I just wanted to get feedback from people more experienced or who have made their own hot end to see what drawbacks or pitfalls they can forsee. I am also thinking about adding an internal brass tube for the filament feed.

Thanks in advance.

What do you have in side the lamp tube hardware? The hole in them would be much too large to work. Needs to be no bigger then 3.4 mm for 3mm filamet and 2mm for 1.75. Unless you found some with that small of hole.

Great initiative! However, I would put the mounting plate further away from the nozzle.

Maybe there are easily-available heater blocks, I can imagine that finding a good heater block may be the most difficult part of your design.

Also, it doesn't have to be that long, I think you can get away with a shorter barrel. I am using a 30mm fan to cool things down, looks like yours is also 30mm?

Good luck with your development!

"What do you have in side the lamp tube hardware? The hole in them would be much too large to work. Needs to be no bigger then 3.4 mm for 3mm filamet and 2mm for 1.75. Unless you found some with that small of hole. "


I'm thinking of soldering a brass tube to the inside of the top cap once the push connector threads are tapped because the inner diameter of the threaded sections is quite large. Thanks for the dimensions.

Edited 1 time(s). Last edit at 12/30/2013 07:39PM by nicklogan.

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Ohmarinus
Great initiative! However, I would put the mounting plate further away from the nozzle.

Maybe there are easily-available heater blocks, I can imagine that finding a good heater block may be the most difficult part of your design.

Also, it doesn't have to be that long, I think you can get away with a shorter barrel. I am using a 30mm fan to cool things down, looks like yours is also 30mm?

Good luck with your development!

I'm going to try making a heater block from 3/8 inch aluminum using a standard 12V 40 W cartridge heater.

Once I get this hooked up and heated up I'll need to play around with the number of washers,total length, fan size, etc. The fan pictured is 60 mm, maybe too big?
The brass connectors may be able to be elimanated but I want see how they work as a heat brake/vent once they're drilled.

I'll update with results as I get time to work on this. I have yet to even power up the RAMPS controller.

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nicklogan
I'm thinking of soldering a brass tube to the inside of the top cap once the push connector threads are tapped because the inner diameter of the threaded sections is quite large. Thanks for the dimensions.

Be careful of the solder you use, most common solder has a melting point near the running temp of the hotend.

A little more work was done on this - the cap nut was filed using a drill press to a cone with ~2mm diameter flat tip, a brass tube was cut to length and one end tapped to thread onto the inside end of the push connector threads, the brass tube was lined with a slighly longer teflon tube that ends just above the inside of the nozzle, and the brass connectors were drilled for ventilation around the interior brass/teflon tubes. A heater block was cut from scrap aluminum and drilled for the nozzle shaft and heater cartridge along with splitting the side and tapping a tab to allow clamping the cartridge. I'm waiting for a carbide bit set to drill the nozzle and then will set up the controller and see what happens.

Edited 1 time(s). Last edit at 01/16/2014 08:51PM by nicklogan.

Looks good, one question, where are you going to mount the thermister?

Wow that looks really nice. Great job.

I don't see a good thermal isolation between the hot end and the cold end. I see large heat sinks which basically will draw a lot of heat from the hot end. This would mean that most of the heat would be dissipated in the air. Did I miss something?

The only connection thermally between the hot end and the cold end is the drilled brass connector at the bottom. The hollow threaded shafts stop at either end of both drilled connectors (top and bottom). The internal brass tube with the teflon liner doesn't touch anything else except the top knurled cap and has an air channel connected top to bottom by the drilled holes. The bottom brass connector has teflon washers at the top and bottom. I'll see whether that's enough isolation once I get the controller and thermister wired up.

Edited 1 time(s). Last edit at 01/17/2014 02:49PM by nicklogan.

SheldonE, the thermister will go in a small hole in the heater block I haven't drilled yet with a little high temp silicone adhesive.

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nicklogan
A little more work was done on this - the cap nut was filed using a drill press to a cone with ~2mm diameter flat tip, a brass tube was cut to length and one end tapped to thread onto the inside end of the push connector threads, the brass tube was lined with a slighly longer teflon tube that ends just above the inside of the nozzle, and the brass connectors were drilled for ventilation around the interior brass/teflon tubes. A heater block was cut from scrap aluminum and drilled for the nozzle shaft and heater cartridge along with splitting the side and tapping a tab to allow clamping the cartridge. I'm waiting for a carbide bit set to drill the nozzle and then will set up the controller and see what happens.

Nice work it's good to see somebody able to think on their feet and be a good fabricator and use what's available don't get discouraged if at first it doesn't perform well as you like. I don't think anybody's put together a hot end that worked first time even fancy engineers that crunch all the numbers. You have to do a lot of testing and speaking from experience as I have designed and built one myself to good luck

Edited 1 time(s). Last edit at 01/17/2014 08:54AM by cnc dick.

actually looks like it would work. i would switch out that brass tube that is over the tubing and make it stainless steel for strength. you would be surprised how much back pressure is created, also taek care in cooling the top and make sure it does not contact the plastic extruder directly because it will get hot enough to soften the plastic. with proper air cooling this may work well for abs!

Edited 1 time(s). Last edit at 01/17/2014 04:03PM by jamesdanielv.

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jamesdanielv
i would switch out that brass tube that is over the tubing and make it stainless steel for strength.

I had some SS gas line tubing around so I did that. The diameter and wall thickness are larger so there's less air space around it so I'll have to eventually try it and the brass to test the difference (if this works at all - I'm still working on setting up the electronics).

Thanks for the suggestion.

I finally found time to get the RAMPS 1.4 controller hooked up and partially configured. I still have some bugs to work out in the drive and extruder motor settings. The hotend seems to work ok so far, at ~187C the PLA placed on the block starts to get plastic. When it's placed in a vertical position on the carriage the aluminum washers stay cool enough to hold onto while the tip is at 187C. Interestingly, I can feel a plume of hot air coming out of the holes at the top end but the push connector also stays cool enough to hold onto.
Hopefully in the next week or so I'll get the bugs worked out and be able to try extrusion. I'll open a separate thread with motor questions.

@nicklogan:

Nice project, looking forward to your first print.


Is the end effector made from a ridged P.U. foam, and can you say a few words about it.
tks.

Edited 1 time(s). Last edit at 03/06/2014 08:09PM by A2.

The hotend carriage is made from polyurethaned MDF along with all the other components that are usually 3D printed (see the link in the OP). I have CAD drawings reverse engineered from his pdf's that I will eventually post with build photos when I can put a site together. I
need to learn to use blog software first though so it's a ways down on the list. Suggestions for the Linux equivalent of Wordpress would be appreciated.

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nicklogan
Linux equivalent of Wordpress

Um, what? WordPress is web software. It's platform agnostic (at least on the user's end - I've only every tried to run it on a Linux server. Apparently it will run on a Windows server too though.) You can set up a free blog at wordpress.com, or host a WordPress install yourself on your own site/server, like I do. WordPress is very easy to use.

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Ok. ... You can see why I asked for help. Glad to know it's platform agnostic. I'll give it a try.

After making just about every software configuration mistake possible, I got Marlin and Repetier working and tried testing the extruder (see photo). I'm just using manual feed at 10 mm/min , 187 degrees, and pushing out a mm at at a time. I guess I'll try upping the temperature and speed slowly until problems happen. Suggestions are welcome.

I would go straight in at 300mm/min and see what you get.

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Waitaki 3D Printer

A description of this hot end and the delta printer it will be used in has been started as "MDF Delta" on openbuilds.com:

[www.openbuilds.com]

I like the way you make the hole in the head. its totally brilliant !

You could make a series of heads in less than 10 minutes ! ;-)


Do you have a list of items used to make the hotend ?? that would be really keen !

Great job.

Actually, its my video of the nozzle hole fabrication.. - and your right, you can make a whole bunch of them in no time.

Edited 1 time(s). Last edit at 04/24/2014 03:40AM by waitaki.

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Waitaki 3D Printer

Sorry there was no attribution on that - I thought it was clear it wasn't my own but I'll make it clearer.

There's Bill of materials with part numbers and sources in the Files section on Openbuilds.

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nicklogan
Sorry there was no attribution on that - I thought it was clear it wasn't my own but I'll make it clearer.

Hey, no worries Nick - as long as you found it useful, that's what matters!

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Waitaki 3D Printer

@waitaki: well its good, gets to te point and a great way to make heads ! koodos !

It that a laite with a bit chick installed on it ? i'm looking at tools with chucks on them at home and they dont turn as round as your.

and another question, the bit you used, is it the ones used to make PCBs ?

thanks !

The tool is a Dremel style drill mounted in its drill press - layed down on its side.
The drill bit is this type..

[www.ebay.com]

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Waitaki 3D Printer