Tuesday 28 September 2010

WADE Extruder parts printed - And My UP! Bearing finished

They all printed well, just a very small warp in the big part, and it messed up the last top layer for some reason?

The big Cog is perfectly flat, I can't really understand why, I was expecting major warp on that.

I am using 2 layers of Kapton tape at 90degrees, I think it's making my prints stick-down better.

I now need to make the hobbed bolt and assemble it then re-calibrate my whole machine again.

I have also started on a Heated build-bed so as soon as I get both working I can start to print my parts for mendel.

I also forgot to mention that I re-started my UP! Bearing print (by hacking the first 27 layers out of the GCode), it finished and the bearing worked !  I'm still amazed that it all fused together especially after a long gap between printing the first half and the second.
See the blue line -

And it rotated 180 degrees.

This is full-size, I did try a another at 50% size but that didn't work very well.

It's printing the Stanford Bunny at the moment to celebrate getting my extruder parts made.
- Bunny - http://www.thingiverse.com/thing:3731 -check it out, a great model.


Monday 27 September 2010

Printing Upgrades - Progress update

I have not had much time to print or experiment with my Repstrap in the last week, but it has been hard at work printing my first Geared Extruder parts so it can start to upgrade itself.

Tweaking and tuning for better Quality has been very worthwhile, it teaches you lots about Fused-filament limits and also about you'r specific system, you can't learn everything from a Wiki, Forum or Blogs, the best method is try it yourself.
For now I have settled on the following settings so I can start to print out some practical upgrade parts.
This is not the best quality, but I'm getting minimal warp and speed is not bad - 
A print speed of 1000mm / min
0.4 layer height
0.5 Nozzle size (but I'm going to make and test a 0.7 shortly)
One outer shell (2 shells when printing gears)
1.5mm Infill pattern (45 and -45)
Outline at 90% speed.
Basic Pinch-wheel Extruder (That I'm very impressed with actually)

Still not using accelerations in my firmware, but as soon as I have a working Geared extruder, then I'm going to re-tune the whole system again and switch Accelerations back on to try getting the speed up.

Print 1 on the far left was the very first thing my machine printed.

Print 2 was 1.8mm infill and slow, ok quality, but not correct Extruder settings.

Print 3 was much too fast. Good extruder settings, but the motor was skipping steps (you can see loops of infill at the front).

Print 4 has just completed, 1000mm/min 1 outline and 1.5mm Infill, nice and smooth, and feels strong.

I printed a few other things, to test some of the earlier settings - 
Whistle - (Version 2) - http://www.thingiverse.com/thing:1046

Probe Holder - (only 50% printed, I decided I didn't need one that badly) - http://www.thingiverse.com/thing:3525

It's printing the Geared Extruder Block and both the WADE gears Now, so I will hopefully be able to Blog them tomorrow.


Wednesday 22 September 2010

How I made my Basic Extruder -

I Just thought  I would put up a few photos showing my first basic extruder, it's working very well and I have used off-the shelf Aluminium 16mm clamps -

You can get these from many places for just a few pounds each (£1.50, $2, 2Euro).

These both hold it to my Repstrap frame and also constrain the PEEK/PTFE hot-end.

It also has the added advantage of cooling the hot-end PEEK, so less of the heat travels up towards the extruder - all good things.

It's just a basic Pinch at the moment, I plan to print a Geared Extruder over the next few days and use the same 16mm Aluminium mounts on that.


Monday 20 September 2010

Warp Factor 9! - Printing the PP3DP (UP!) Bearing on My Repstrap

So maybe a bit over ambitious for a Repstrap with no Heated bed but I had a go anyway.

I really like the UP! Bearing - get it here - http://www.thingiverse.com/thing:3981

Not a bad start - Poor choice of infill size - too many start-stop operations
Starting to warp on the front edge - Note my use of double sided tape! in a poor attempt to counter the warp.
At this point the warp was going to destroy my extruder, so I reluctantly had to turn it off. You can see the bottom front edge getting more and more melted after each pass.

It would have taken about 2 hours 20mins to print in total, which is almost exactly twice as long as on the Up! Printer, I expect it could have be much faster as I had it set on 2 x Shells and a slow outline speed. it was also resetting to origin after every layer.

All the bearings are clear and I think would have moved and worked if I could have printed it all.

If anyone has a Mendel with a heated bed, I would love to see if this could be printed and if it worked afterwards. - Let me know...

If you want to try - You will need a support structure;  -
I made a 1.7mm high ring positioned under the balls to get them to the correct height in the bearing. For me the balls started to print after layer 4. The ring needs to be 58mm outer and 46mm inner. - Good Luck !

I really need to stop messing about and print some upgrades for my extruder, but it was lots of fun trying to print this.

I really want a heated build-bed now...


Sunday 19 September 2010

Compare the frog

I was getting bored of printing test cubes, so I spotted a small frog that looked like it would be an interesting challenge to test quality, and sure enough I discovered something...

Test frog from here - Frog by Owenscenic - it's the little one test frog.stl (there is also a big one, I may try later)

So I printed the first frog (placed in the top right in the photo below) and he had quite a lot of brown bobbles on his left hand side (the side closest to machine 0 - origin).
So on the next test print I re-enabled the shield option (frog on the bottom left) You can see that the shield wipes off the spare ABS and stops brown bobbles, it also seems to make less string-bits and gives a better overall end result.
Compare the Frog ! - Left with wiper-shield and Right without.

Prints are sticking really well now to the Kapton tape. - but I may have problems when I try to print larger parts.

Some close-ups for a review of Quality -

This is the underside of the above frog, nice and glass-shiny, and the next layer looks well fixed to the base.

This is a close-up of infill using a 0.8mm infill gap, looks quite a nice uniform hatch.

This is infill with a 1.5mm spacing, slightly more sag.

Overall I'm very happy with my basic pinch-wheel extruder, I didn't think it would be very good and I expected to be wanting to print a geared replacement ASAP, but at the moment I'm having too much fun printing other stuff, mind you a big gear would also be a good test...

On with printing -


Saturday 18 September 2010

Calibration... Cubes... Lots and lots of cubes...

I finally found time on Friday night for some more testing and some further calibration of my Repstrap machine -

The test and calibration model that is included with Reprap was a bit over-complex to start with so I used the Makerbot Calibration set by Spacexula http://www.thingiverse.com/thing:2064

Printed a few 20mm Calibration test cubes to start with -
Cube on the left has the start point at the corner, and on the right it's in the middle, this told me that too much material was being extruded as it tends to blob and then over-heat at the pause before building.
So I made the reverse fillament longer, and reduced the extruder speed very slightly and also made the wait time before building short (only 100ms) this fixed most of the blob problem.

So Now I have a better start, but it's not smooth enough, so more tweaking required.
I also started using Kapton Tape on the Polycarbonate build-base, this works really well to stick the print down as I don't yet have a heated bed.

Infill changes  -  Cube on left is 1.2mm infill gap, on the right it's 0.9

Size is not bad, and it's square

Slightly too small, not sure why? it maybe the foundation layer setting, this seems to be causing me more problems than it's worth, so I'm going to switch it off for the next print - 

Reprap Host has a large number of settings, especially for the extruder's so It's taken a fair bit of time to get my head around them, but it's starting to make sense now.

I'm getting tired of cubes now so I'm going to print some of Wade's Extruder parts today, and maybe a frog or two.

Monday 13 September 2010

I start my Blog with Success!

Hello everyone and welcome to my Blog.

This is going to look the wrong way around as this first Blog entry documents some initial printing success with my home-made RepStrap printer (a Repstrap is a lashed together 3D printer with the aim to print enough parts to make a real Reprap printer) - See - http://www.reprap.org/wiki/Main_Page

So here we go - 

Very late on Sunday I got my Repstrap to print. Here are some photos from its very first go.

I had the nozzle/bed clearance calibrated with sheets of paper as I don’t have easy adjustment yet and in my excitement I didn’t do a test-run so I was slightly alarmed when the nozzle moved down at the start into my Polycarbonate build surface, I should have remembered that Mendel has it’s zero position just off to the side of the build-bed!
I then thought it was not working after waiting a long time at the dump position, by that point I was very tired and about to turn it all off… then movement!

Here is what I ended up with about 10mins later – 

I think some of the discoloration is due to excess material from where one wall snapped off (removed that bit), but after a while the spare material started making a bit of a mess so I stopped it and went to bed.

It also seems quite fused to the PC bed, so maybe the bottom layer was a bit to close, maybe melted into the PC?

Registration looks ok, no missed steps?

Microscope close-up looks like the walls are well fused? 

Do you think enough material is being extruded? Or too much?

Setup –
Extruder hot-end - Hybrid PEEK/PTFE from Brian (http://forums.reprap.org/read.php?1,36084) ,really glad I bought this bit, works well.
Extruder drive – Not geared, loosely based on a basic 8mm direct-pinch drive grip – NEMA17.
Accelerations - OFF
Natural ABS – set to 243 Deg C.
3mm Polycarb bed and 18mm MDF. 

OK, If you are not very impressed with the above effort, this is what it should have looked like -  

I’m going to try to refine and calibrate it now, so any suggestions welcome, I then need to print a Geared extruder!