Peter Wallers Robot Ramblings

[Shakey]

If you wanted a test print doing on a hotter printer my one has a hot end that'll hit 350 degrees.

[Roboteernat]

Peter, you really need to get a new hot end for your printer.
A nice all metal one will be great, as you know, the PTFE tube will melt and cause major issues. Mine 'melted' at 260 causing me to strip it and re ream the hole.
Btw is it an i3 you have?

[peterwaller]

Yes it is an Prusa i3 and an all metal head is on my to do list any suggestions / recommendations always gratefully received.

[Shakey]

You can never go wrong with an E3Dv6 and titan extruder. It's the setup I put on mine and it prints brilliantly. It does make some filaments a little more prone to jams though as the increased metal portion of the hotend increases friction.

[Roboteernat]

I would agree on the E3D hotend, I have 4 of the things on my other printers and all great - well, 2 are official E3D and 2 are Chinese copies.
All still are great, but finish quality of the chinese is as you expect!

[peterwaller]

Just as I think I am getting the hang of 3D printing it throws me another curve ball.
As I mentioned I have had problems with the Nylon distorting when its thin so I had thickend up the chassis scoop and lifting arms on flippant as I had plenty of weight in hand.
Having got the de-laminating apparently sorted I decided to print the arms in Polycarbonate as it is stiffer and the first came out fine but the second had a complete de-lamination down the center of the curved self righting part. I checked the drawing in X-Ray mode and all appeared fine so I decided it was the old trouble back again and that I would have to use he Nylon.
So I changed the material and printed the same arm in nylon and it came out with the same de-lamination.
I then looked at the part in Cura layer by layer and sure enough the slicer seemed to think there was a slight gap there so it was not the material.
In the drawing I thinned the part down past where the problem was and the stretched it back to the correct height and now Cura sees it as Ok so I am back printing it in Polycarb.
Are well at least it keeps what few grey cells, I still have left, functioning a bit longer.

[peterwaller]

I have finished the Nylon and polycarbonate parts for flippant here is the existing chassis with the new arms and armour which is 3mm on top and 3.5 at the sides which now extend further over the wheels.
I decided most of the distortion in the thinner parts was due to dying them at too high a temp almost boiling so these parts were done at maximum tap temp which I estimate as between 50 and 60 C.

The thicker armour has added about 15 gms but as Flippant was carrying 25 gm of ballast it is not a problem.
I also have a new nylon chassis with thicker sides and rear wall which you can see below with open flippant.

[Roboteernat]

Looking very nice, I like the contrast of the blue on white.

Curve balls are always apparent on my printer, that's why I bought the wanhao printer as it was a work out the box, my I2 just took so long to set up.
I wonder how a multi material layup would work, using the 2 nozzles, how would laminating both materials onto each other fair?

[peterwaller]

Yes the blue and white do go well together although the off white HI ABS chassis isn't quite as good but I have a blue nylon chassis and a white polycab one to chose from.
After all the experimenting with materials I finally got the walker fully wired up and working it came out at 163 gms so 62 gms under weight.
Although it does run upside down it is much slower and unlike wheeled robots it is the steering that is reversed not the drive so I am considering a self righter.
I am not sure if it is going to be competitive enough for the AWS but if it is here is the latest all nylon armoured lineup.

[peterwaller]

On the subject of 3D printer hot ends I have been reading up on them and one of the biggest obstacles seems to be the heat transfer.
The all metal ones have to have a thin walled tube between the nozzle / heater block and the feed system and it requires a fairly large heat sink / fan arrangement to further cool the feed tube.
It seemed to me that maybe the introduction of a section of ceramic tube between the two would greatly reduce the heat transfer without any of the melting problems associated with PTFE above 260 C.
So I spent a while discovering that ceramic tubing in short lengths (It is very difficult to machine) are difficult to obtain easily so I started trying to think of something that was already produced that contained a ceramic tube and decided on the humble ceramic fuse which I already had in the garage.
I haven't got much further with it yet except a not to scientific test where I removed one end cap, took out the fuse wire and sand and held a soldering iron on the other end cap while holding the the ceramic end in my fingers. After 3 mins it got to the stage where I had to move my grip but wasn't to hot to touch.
The fuse I was using was one of the old 1.25 inch ones so the ceramic tube is 31 mm long with 5.84 mm OD and 2.58 mm ID so would be good for 1.75 mm filament.
I am not sure if I will end up trying to design a new hot end or not but I recon it is worth playing with a bit further at least.