Help me make my objects warp!

I am looking for suggestions for a test object which is prone to corner curling. I've had this happen on a few objects like this one (http://www.thingiverse.com/thing:662862), not very badly, but enough to be annoying. So now I'd like to find an object that I can print quickly and is likely to distort in the same way, so I can quickly experiment with some remedies for fixing it.

This is with PLA on blue painters tape at 195/185, bed 70, 0.4mm first layer, 0.3 thereafter, though that's not directly related to my question.

A shape thats long and thin would have a tendency for pulling up.

Here's one of the parts for a 3D printer I'm designing—so far it's been extremely prone to warping and also doesn't use that much plastic, so it would be a good piece to test with.

Edited 1 time(s). Last edit at 06/23/2015 01:04PM by AlexY.

Quote
AlexY
Here's one of the parts for a 3D printer I'm designing—so far it's been extremely prone to warping and also doesn't use that much plastic, so it would be a good piece to test with.

Looks great - thanks! I'll try it tonight.

No problem—I also get occassional problems with warping, since I'm using an unheated bed with blue painter's tape. I'd be interested in solutions to this issue, so please post what you find!

Also, I remember reading that when using painter's tape heating the bed actually lowers adhesion, though I've never tested that myself.

With PLA I never had warping or curling issues on a cold bed.
Although for long parts I had the problem of the tape coming loose.
One thing I noticed is that the thicker your layer heights the more a part tends to warp.
Having said that, lowering the speed for the first 4 or 5 layers also helps me in such cases.
It gives the plastic more time to cool down and get into shape.
Once the lower layers have cooled down enough so the print won't warm them up the parts are usually fine.
Have you tried a circuit board?
I mean the big blank ones for etching your own circuits?
Using plastic primer on the copper side give a nice, flat surface and parts stick like mad, especially if you used a steel cleaning pad on the copper first.

Thanks for all the suggestions everyone. I tried AlexY's crossbrace object, and a thin brick (50mm X length, 5mm Y length, 10mm Z height) that I made in Blender. I haven't been able to get any corner lifting, even with settings I was using before. It may have been some factor to do with the objects I was printing a few days ago. It might also be that it was hotter and a little more humid at the weekend. Anyway, for now I'll just have to accept that my printer is working, and if I get problems again, I'll try the suggestions here to see if they help. It's only a week since I've been up and running, so I don't have much sense of what factors affect print quality.

What's that plastic primer that you mention, Downunder35M?
Sounds interesting.
-a