Friday, December 28, 2012

Excalibur Mini Hotend

Today I received a new fan.

Its size is 25 x 25 x 8 mm. Quite small, so to speak.

Now I am planning to design a new hotend around it: Excalibur Mini.

Btw I renamed the Organ Pipe Hotend + Mk IV to Excalibur Hotend. You can find its description here.

Here it is printing.

Wednesday, December 19, 2012

Warping - Some Findings

Today I tried some settings in Slic3r. Doing so I printed a U-shaped testcube of PLA on a heated mirror. I printed the first layer at 200°C and the subsequent layers, too. It looked quite well, but at one corner it hadn't stuck to the bed as perfectly as I wished. Actually I wouldn't call it warping already, but maybe the very very beginning of it.

So I cleaned the mirror with alcohol. Then I printed a second cube with 200°C at the first layer and the other layers at 170°C. My expectation was a reduction of the warping, as a layer with a lower temperature wouldn't shrink that much like a hotter one.

The result was puzzling. The second cube showed strong warping.

To be sure I repeated the printing and printed a third cube with 200°C/200°C and a fourth with 200°C/170°C. While the third one again showed no warping, the fourth cube warped so much that it got off the heated bed and I had to abort the print.

Obviously the reduction of temperature at the second layer weakens the bond of the first layer to the bed. Maybe the "cold" second layer cools down the first one and causes it to shrink. Once the first layer got off the bed the whole part is an easy prey to warping.

Possibly this temperature difference explains a lot of cases of mysterious warping. A little option in the slicing software turns out to be a trap ...

I guess I will repeat this with ABS soon.

Tuesday, December 11, 2012

Mk IV is printing

Today Mk IV got ready.

After making the parts

they were assembled.

It extrudes ABS very well.

For the first time I dared to bore a nozzle with a cheap 0.3 mm PCB drill on my drill press. The drill went through the brass without any difficulty.

The nozzle prints very well. Unfortunatly I broke my 1 mm center drill on Saturday, so I had to use and ordinary 3.5 mm drill for the inside of the nozzle.

Monday, December 10, 2012

Just solder it

Well, crimping a stainless steel tube actually isn't very easy, as I had to learn. So a solder free solution isn't really in sight.

Furthermore I do not like the gap between the screws caused by the crimping, as it hinders the flow of molten plastics. Therefore I came up with a solution, where the barrel is soldered to the upper screw.

I think this solution is the best one as it leaves no gap open and allows me to change the barrel and/or the nozzle. In fact I only need two barrels (one for ABS and one for PLA).

So I've begun to make the barrel.

Next step will be the nozzle.

Sunday, December 9, 2012

No more soldering?

I am thinking about a hotend which can be made without soldering. The idea of crimping the barrel came up in the reprap forum. After some discussion I suggested something like the following solution.

To be honest I don't know, if I prefer such a solution. What I don't like about it is that the nozzle has no contact to the bottom of the heater block. The head of the screw will have a cooling effect on the nozzle this way. It should touch the heater block thus.

Maybe this solution is better:

Saturday, December 8, 2012

Pipe Gallery

Here is a picture of the pipes I've made up to now.

The Mk I pipes extruded only PLA while the Mk II and Mk III extruded ABS.

The Mk III is by far the easiest to make. It starts with a simple screw.

It is amazing to see how this tiny piece of brass easily turns into a nozzle. My new nozzle sharpening tool speeds up the making of the nozzle significantly.

A few tools more and I am ready for mass production. :)

Nozzle Sharpening Tool

There are two kind of people in the world: Those who have a lathe and those who don't. Unfortunatly I belong to the latter one.

Actually it isn't very comfortable to build the cone of a nozzle without a lathe. So I constructed a little tool like a pencil sharpener.

The two black parts are cylindrical milling cutters. They do not rotate.

All I have to do now is to put a M6 screw into the chuck of my drill press and to turn the lever. I guess even with a lathe it would be more work.

Wednesday, December 5, 2012

Pipe Mk 3 in Action

The Mk 3 pipe turned out to be a great progress. Not only is it much simpler to make, it extrudes very well. I am satisfied.

 The organ pipe hotend extrudes ABS.

The calibration still has to be done ...

 ... but I am impressed by the quality.

Up to now I only used Skeinforge, but this is the first time I used Slic3r. 

In the past I had difficulties to extrude this spool of ABS at all. I seriously thought about throwing it away.  But the organ pipe hotend does its job very well.

Even the leaking of ABS at the soldering areas has gone.

No ABS leaks out.