Sunday, January 24, 2010

making Mendel element on Welding tip and Torque test video

An in focus picture of the shorter Extruder with long wedding tip made in December.

Here is the New longer Peek insulator with the shorter welding tip.

The insulator anti twist securing hole drilled out read or a 3mm screw.

With the screw fitted and a bevel to aid the alignment of material being extruded this was made using the tip of a 22mm flat wood bit.

The brass inserts were removed from a standard plastic 3A chocolate block attached to my last 7 ohms of cotton covered nichrome wire.

The red cable is attached to one end of the element and taped to the Peek insulator using 200C heat resistant Kapton tape its ready to wind the element.

Element wound ready for the Black wire end of the element to be taped up.

Taped up twice on the long Peek insulator.

The end on view now with a K type thermocouple slid in under the layer of Kapton tape its the green wire.

Last months heated barrel looked like this before the high temprature black self amalgamating tape was put on.

Now for my second Video where I miss getting the scale showing 2Kg for the second or third time each time destroying two foot or more of ABS welding Rod as the splines eat it up as it starts to slip and yes it had already stated to slip by the time I got the camera to focus on the digital scales Ahhhh. We decide to give up before we had got any more frustrated by trying to film it.

Testing the new splines shaft in my perspex clone of the Mendel extruder block with 3mm ABS gave a maximum of 2kg of pull measured before the ABS starts to be eaten away by the splined shaft.

Now we know that Wade has achieved 5.5kg of pull without slippage.

So whats was the difference.

Nophead is using the AKA47 "worm" pulley. It is 15mm OD, ~13mm ID using an M4 tap

And has suggested halving the ID to 6.5mm and using a M3.5x0.6 tap with an OD of 10mm

The other difference is both Wade and Nopheads extruders have a spring tensioner to control the pressure of the grip.

Where as the standard Mendel extruder has the pressure set by setting up the gap to be 2.5mm between the bearing and the splined shaft using a drill.

I tried using a 2.4mm drill this had no effect on the grip.

Using the AK47 "worm" pulley makes a lot of sense as it will be gripping more of the ABS.

So tomorow that will be my next Job.

Many thanks to Nophead for all his marvelous pioneering work on extruders and extremely detailed blogs.

Not forgetting AK47 and his great "worm" pulley blog entry the next task is to make a new acrylic block tat can incorporate the "worm" pulley
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