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All steel hot end for Makerbot

by lampmaker, published

All steel hot end for Makerbot by lampmaker Jun 29, 2010

Description

This is an alternative extruder hot-end design for the makerbot, though it may work for other 3d printers as well.

The big advantage is that it does not require an insulator (usually PTFE or PEEK), which causes problems for some (or perhaps many). Instead, a stack of washers and nuts is used as a heatsink to reduce the temperature.

It worked really, really well for me, no more stalled extruders, stuck filaments, half-way prints. It heats up rapidly less than 1 minute from 25 to 220 degC), and I haven't had any problems with it (yet..).
I've only printed ABS so far, so I have no idea if it will work with other materials.

My original version used an aluminum heatsink (bottom image), but I thought that might be a bit hard for others to duplicate, so I built this one. Works just as well, just looks a little less fancy.

You'll need a small fan, stainless steel M6 bolt as well as a stack of M6 nuts and 25mm M6 fender washers in addition to asome components from a standard makerbot extruder.



Recent Comments

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is the drill bit size of 3.3mm for 3mm filiment or 1.75 filiment?

Some further tips for using a drill press for the hole:

- use a center drill bit first to prevent the drill from slipping off center (this makes it much easier!)
- instead of using two nuts, use a vise with a triangular notch on one side (dont clamp too hard to keep the threading intact)
- if your drill is too short drill from both ends
- make sure you do not tighten the vice while clamping a part of the bolt that was already drilled, or you will deform it easily

I got a nice clean 3.3mm hole in a M5x60 bolt using that method (the remaining wall thickness is only about 0.35mm). Using a M5 bolt should make a better thermal barrier than a m6 bolt, but I am not sure if it will make a huge difference in practice.

I`m thinking about creating higher thermal barier (3cm) and using smaller aluminium heatsink on the top. What do you think about this idea? thanks :)

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Instructions

1 - Cut the M6 bolt to 65 mm length. Make sure the ends are flush, use a lathe if possible.

2 - drill a 3.2 mm hole in the bolt, all the way through. You'll likely go through a few bolts and drill bits before you have something good. Take your time. Slower is better. If you don't have a lathe, use the "afghan lathe" method or a drill press. (Check instructions at bottom how to use a drill press for this).
Note: This is fairly hard to do nicely. You'll probably have to drill from both sides, with the risk that the holes won't align up properly. If that happens, you could use a larger drill to enlarge the hole at the cool end, to make sure the filament feeds through well. I got it right at the first try, but I was using a lathe. Get a few extra bolts and spare drills before you start. Or go to a local workshop and ask if they can get it done for you.

3 - Create a thermal barrier by reducing the diameter of the bolt to 4.8 mm, over 10 mm length, starting 10 mm from the bottom end. Check the images (IMG_1744) for details. You can do this on a lathe, or simply with a file.

4 - Nozzle: (IMG 1740) cut the makerbot nozzle in height, leave around 5mm of height for the hexagonal part. Make sure the end is flush.

5 - Heater: (Img_1745) I decided to make it separate so it can be removed or exchanged easily. Cut the threaded insert to about 5-7 mm length. Make sure the end is flush. Wrap the nichrome around it and fix with kapton tape. (refer to the standard makerbot extruder instructions if you've never done this before). Start wrapping in the middle, then up and down a few times to make sure the nichrome doesn't easily slide off.

If you can't find a threaded insert, use something else that has M6 thread and an outer diameter of about 8mm. Brass is probably the best.

6 - Heatsink: The washers are just a little too large to fit in-between the M4 bolts that nurmally hold the extruder. Cut some notches in the washers to make them fit.

7 - Assembly:
Screw the heater onto the low end, followed by the nozzle. Tighten the nozzle first, then tighten the heater against the nozzle. The heater should sit tight to the nozzle. If there is a gap between the heater and nozzle, it will be harder to transfer the heat to the nozzle. It may still work, though. (img_1748)

create a stack of M6 bolts and washers, include the MK4 retainer washer is at the bottom. Tighten everything well. Make sure the notches in the washers are aligned with the holes in the MK4 retainer washer. (IMG_1756)

Don't forget the thermistor and the insulating blanket. (IMG_1758)

Mount everything with the M4 bolts that came with yoru standard MK4 extruder. Check the length of the bolts, you may want to use a few washers to make sure you don't break the plastic housing.

Last (but not least): use a fan to cool the heatsink It may work without, but if it heats up too much, you may break your extruder housing. You can mount the fan on the extruder platform with a dab of hot glue.



Drilling the 3.2mm hole with a drill press
- Put two M6 nuts on one end of the bolt, tighten them well.
- Mount the other end in the head of the drill press.
- Clamp the two nuts in a vice and fix / fasten the vice.
- Open the head of the drill press and move it upwards.

You should now have aligment between the axis of the drill press and the axis of the bolt.



Comments

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chevydan6 on Jan 10, 2014 said:

is the drill bit size of 3.3mm for 3mm filiment or 1.75 filiment?

mblaster on Mar 12, 2013 said:

Some further tips for using a drill press for the hole:

- use a center drill bit first to prevent the drill from slipping off center (this makes it much easier!)
- instead of using two nuts, use a vise with a triangular notch on one side (dont clamp too hard to keep the threading intact)
- if your drill is too short drill from both ends
- make sure you do not tighten the vice while clamping a part of the bolt that was already drilled, or you will deform it easily

I got a nice clean 3.3mm hole in a M5x60 bolt using that method (the remaining wall thickness is only about 0.35mm). Using a M5 bolt should make a better thermal barrier than a m6 bolt, but I am not sure if it will make a huge difference in practice.

mihalko on Feb 1, 2012 said:

I`m thinking about creating higher thermal barier (3cm) and using smaller aluminium heatsink on the top. What do you think about this idea? thanks :)

Lutz95326 on Dec 13, 2010 said:

Hi lampmaker,

your original aluminum heatsink looks very good.

I want to reproduce it an have a few questions:

Is there a M6 tread in it for the M6 bolt on the whole length?
Goes the M6 bolt through the whole aluminium heat sink
or is the bolt screwed in the aluminium?

Please give me a short answer
Thanks
Horst

neorazz on Aug 18, 2010 said:

try this method to drill ling tiny holes
http://vik-olliver.blogspot.co...

spin the workpiece instead of the drill like a metal lathe would and if you have an extra drill chuck
clamp it in the vise to perfectly center and hold small pieces (acts like 3 jaw clamp)

peter_ on Aug 3, 2010 said:

This is a fantastic design, thank you! I've just posted a derivative, http://www.thingiverse.com/thi... , that uses a modified version of the original MK4 brass barrel.

Bench on Jul 19, 2010 said:

I have built this design with a slight modification to the heatsink washers, basicly increasing the surface area of the heat sink by having groups of different size washers as well as the nuts.

I did have a small issue of having the barrel line up with the body of the print head. This was easily solved by placing a small abs rod into the hotend before attaching it to the body forcing it to line up.

Works great although i have been told to put some scented oils or something similar behind the heatsink fan due to it spreading the abs smell through the room

jglauche on Jul 1, 2010 said:

Hm, drilling 3,2mm through 65mm of steel isn't really doable without bending the drill. One hole would end up off-center.

lampmaker on Jul 2, 2010 said:

If the cool end ends up being off-center, it really doesn't matter much. You could actually drill the cool end with a slightly larger drill.

Anonymous on Jul 1, 2010 said:

I Don't believe it ...... I am working on exactly the same thing.

Well it's good to know it works I suppose.

I would like to add a few extras if I may.

When drilling through the bolt use a colbalt/carbide drill bit.
More expensive but they don't explode like the cheap hss ones did.

Also you may find that the bolts have been hardened. I found popping them into a fire and leaving it in to cool made the
metal more ductile. This is called annealing.


&
amp;gt;:o

lampmaker on Jul 2, 2010 said:

Good points. Drilling the hole is certainly the most challenging part of this thing. I ended up breaking 2 drills before I got it relatively right.

Anonymous on Jun 29, 2010 said:

When I demo'd a Dimension printer I noticed they have ZERO insulators, except for some foil tape, only a tube and extrusion tip. Its then inside a heater block. I have a Makergear plastruder but my old blown extruder is getting this treatment.

jstiltner on Jun 30, 2010 said:

I haven't looked in our sst at work, but our old dimension 1500 and 1600 both have an non metallic part where the filament enters the liquifier (Dimesnsion speak for the heater barrel) Also don't forget that ambient temp air is forced into the back of the nozzle box where the motors are and also where the filament enters the heater. If this airflow is stopped the filament melts all the way to the outside of the heater unit and ends up mushrooming and going all over the place. Photos of this to come soon, as soon as it happens again at work!!!

tbuser on Jun 29, 2010 said:

This looks awesome, what is the temperature at the top of the barrel? Also, where do you mount your fan?

lampmaker on Jun 29, 2010 said:

The temperature on the top was about 40 degC with the fan on. The fan is mounted on the extruder platform.

Anonymous on Jun 29, 2010 said:

Is it me, or is this thing starting to look more like a Ray Gun?

Yocttar on Jun 29, 2010 said:

Agree. O:-)

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