ABS print temp vs strength

So I designed and printed a turn signal indicator mount for my motorcycle and I intentionally made a thinner walled section of the stalk so it would break there at impact instead of stressing the bike's side panel to which it is bolted. The main section of the 19 mm diameter stalk tube I made 2.0 mm wall thickness and the thin section 1.5 mm. But the part really was too fragile. The issue it that the way I printed it every new layer is a potential failure plane when a bending moment is applied. But that was the best way to print it with a flat side down on the work bed. So, I was thinking that I could maybe increase the strength and adherence between the layers by increasing the print nozzle temp from the 230C I use for ABS. Maybe to like 240 or so? Would that help? Or perhaps some post print "sintering" in a toaster oven?

you'd be better off not bothering with abs and using pet-g.
Much better layer adherence and generally stronger all round than abs.
Plus much better to print with.

The thing with abs is that unless you keep the entire model at around 60c until your model is finished and then cool it down gradually, the layer strength will be crap. Because it' designed for injection moulding, it shrinks quite a lot (to make it easy top remove from the moulds), and unless you keep the whole model the same temp and quite a high temp, each layer will shrink slightly all by itself, destroying the inter layer bonds.

Basically it's damn near useless for fdm unless you have a very good print volume heater.

Why didn't you tell me this before I bought 2 spools of ABS?! ;-)

I think you'll find I did - I have a shelf full of the damn stuff, can't even give it away.

I still have no clue why people insist that abs is good for fdm printing. Pla is stronger and more durable. Pet-g is super strong and has fantastic vertical layer strength.
It's all down to layer adherence and with abs you don't get that unless you - essentially - print it inside an oven :-)

Plus neither pla or pet-g make your workshop stink like a plastics factory.

And I was just starting to like the ABS fumes! To my nose they aren't as bad as the cloying sweet PLA... maybe more toxic, tho.

So what about post-print "sintering" or "annealing" of an ABS part to improve strength? I guess it would be tricky to get the right temp and duration.

I doubt that would work very well; any thermoplastic part will tend to distort as it approaches its melting point. Treatment with solvents can help with layer adhesion and surface smoothness, as will dips that add material to the surface - both at the expense of detail, unfortunately.

Well, I have ordered a spool of PETG. Simplify 3D doesn't appear to have a PETG profile for my Qidi X One printer so I guess I'll have to manually set bed and extrude temps.... and figure out the best work table prep. What works for you guys? I have a glass plate installed that works great with hairspray for ABS at 100 C and seems to work great with a plain clean surface for PLA at 45C temp.

Yes, my X One is the V2 enclosed version. It prints ABS just fine, especially using glass bed with hairspray. I have printed coasters, and some large hooks to provide tie down points in my pickup truck bed. It is just that in this particular application for the turn signal the orientation of the layers creates weakness in the direction of stress. As Curious A says the layer adhesion isn't great with ABS so it fails there too easily. I remade the part in PLA whilst waiting for the PETG and it seems more resistant to breaking. The ABS part would be plenty strong if it could be oriented a different way while printing but that would be a PITA.

Here is the signal indicator mount:

https://www.thingiverse.com/thing:2519402

I reckon with minimal redesign that part could be printed better.
Picture of it in use would help.

Pet-g - bed temp 60c. print temp, I think around 225-230c
Keep it in the lower range for better layer adhesion.

What did you model that signal in ?
Lot of very low facet columns.
More roundness - higher facets makes for stronger parts.

But without any redesigning. Lay it flat and use a few supports along the sticky out bit.
like this:
Attachment 11069

Printed in that orientation it would be at least as strong as injection moulded. Probably stronger.

It doesn't need supports on the long oval part, but simplify3d always adds way more support than is actually necessary.
yeat another reason i try never to design anything that needs supports :-)

Also don't forget that both pet-g and pla are much better for soemthing that's subject to sun and weather. Abs is the worst of the three for uv exposure and breakdown.
Pe-g has best chemical resistance and highest glass point.

The only reason I can come up with why fdm printer users still use abs, is that they've never tried the alternatives and believe all the misinformation there is online.

Yes, I thought about laying it over and printing with supports. Making it strong would be easy. Thing is I don't want it to be too strong. I want it so it will break on impact so as not to damage the side panel where it mounts. These things constantly take small bumps whist maneuvering in tight spaces like parking in my tiny garage. The first ABS one broke my first ride and I don't even recall touching it on anything. It broke at one of the thin wall layers. The OEM piece was rubber and very flexible. It might actually be good to print this piece out of something like nylon. Pics in use at the above link in the "post-print" area. I've installed the PLA version and it looks good. It bends a bit and I tested it with fairly good force and it didn't break.

Oh, I designed it on Tinkercad. I will try to learn something more powerful as time permits. I have signed up for the free version of OnShape but have not had time to get into it yet.