Problems

[sho]

Problems about print result

[sho]

We have to change a shape of "pin" and "hole".
There are many hole and pin on Shellmo, so we will see same problem at them, too.

[robaktime]

I have used similar pins with limited success. The linear stress tends to work them loose even if they don't break. I changed to a post and tube. I have had success even without gluing. I made several with the approximate dimensions you are using and they have potential. They cannot be removed without breaking the cap but they are easy to make in abundance and easy to replace.
If the hole could be slightly larger allowing the pins to be slightly larger it would be a great advantage. It looks like you have some room.
Most the files on Shellmo would be a great challenge on FDM printers but I will certainly try it later this year because it is a very,very nice piece of work.

[sho]

Thank you very much.
I'm looking forward to !

[steamboat]

If a design for the home printer should be successful, one has to forget all kind of fine and fragile structures. I am a member of a 3D printer group here in Hannover and have seen "some" home build printers and what results you can archive with it - don't expect to much. And even if you have calibrated everything and are using best materials, fine structures can be frustrating.

This in mind I have some fear about the durability of all the crank pins and the worm gear of the actual centipede design. This is only a feeling because I have not build something like this with an 3D printer!

But especially the durability is what a design makes successful. Making Shellmo is one part - programming and using it is the other much longer phase!

Building my RepRap 3D printer I didn't care about using lots of not printed parts because I wanted to get a reliable printer - same with Shellmo!

I am just printing RepWalker in ABS and am curious about the durability of its gear - maybe I will be positively surprised ;-)

Rainer

[steamboat]

I changed all pins from 4 mm diameter to 5 mm. 4 mm would be fine for good printers and if you are knowing what you are doing but I want to make it fool proof...

Because I came back to my printer after 6 month and I was using new filament I had to play a little with all the settings. As I started with 3D Printing I was using Skeinforge a lot because of it's possibilities to fine tune everything - maybe a problem of German Engineers ;-) For easy printing I gave Slic3r a chance. But with this fine structures Slic3r had a problem. It tends to not following the outer lines exactly and splitting them at random points. Especially with the claws I had some problems to get them stable.

Now I went back to the free KISSlicer. This is a good compromise of nice settings and easy to use operation. Best of all it don't "invent" new outlines like the Slic3r and produces stable print layouts.

Have a look at KISSlicer here. First the support made the crank pin unstable:



By changing the extruson width and the number of loops I got this result:



Printing with this was easy. I am using a nozzle with about 0.45 mm diameter and printed this with 0.5 mm layer height and 0.6 mm extrusion width.
To get this parts stable during printing I used a Z-lift when moving from one pin to the other, a prime pillar and a little fan to cool it.
It came out verry strong. So if people want to print it with 0.25 mm layer height it would come out even better...


As you can see I have to play with the seam positioning and the seam hiding.

[jmccartney]

I have a feeling some of this is more related to how each program is handling stls that aren't perfect solids. Most of Sho's stls are not perfect solids from what I can tell. Because Sketchup is a "surface" modelling tool is very difficult to keep things "solid" and good strong slices require this and its confusing for the slicers when they reach reversed faces internally etc etc in the model.

I am thinking the other factor is extrusion diameter and part dimensions where the slicer has to figure out how to match them up and they have different algorithms.

I am happy you posted these results because it is interesting how each program is handling them and is really helpful for others.

I am having a similar issue I think on the micropede cranks where makerware is not fusing each cylinder shape were they meet how you would expect a solid to be sliced. So what happens is they snap really easily.

[sho]

Thanks,

In my case, no many times but the same problem occur at Replicator2 with Makerware.(Picture: Red parts)
But, the case of my RepRap with "Cura", no problem (Picture: Blue parts)

If you change CAM to other software, I think it will be difference result...

[steamboat]

I am happy to have a slicer (KISSlicer) which enables me to set layer height AND extrusion width. So I established a design standard of 0.5 in height and 0.6 in width. This makes it easy for the slicer to find a perfect fit. Because we are building small parts with thin walls it is good to have no "air" in the wall.

Therefore all my designs have wall thicknesses of a fraction of 0.6 = 0.6 - 1.2 - 1.8 - 2.4 and so on. An as mentioned above you also can print this with 0.25 mm in height and 0.3 in width...

---

So finaly we 3 are awake at the same time ;-)

[steamboat]

(04-26-2014 11:39 PM)sho Wrote:  the case of my RepRap with "Cura", no problem

Do you have an Ultimaker at home or are you using Cura with an other RepRap printer? I never tryed out Cura.

Can you set the extrusion width in Cura or in your Makerbot Software?