lifting at the corners

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mec949
Posts: 123
Joined: Thu Jul 12, 2012 7:16 am
Location: NSW Australia

lifting at the corners

Post by mec949 » Thu Nov 13, 2014 9:40 am

I am printing a keychain that is a square, 40mm square and 5mm thick.
It is tending to lift at the corners, which doesnt seem to happen with hexagon shapes
How can I stop it lifting at the corners?

Thanks all : )

cj7hawk
Posts: 103
Joined: Tue Dec 25, 2012 7:52 am

Re: lifting at the corners

Post by cj7hawk » Thu Nov 13, 2014 10:12 am

I had lots of lifting problems and mostly ignored it - but then calibrated my raft accurately and haven't had issues since.

Anyway, I find if the raft is solid, it doesn't lift. Perhaps raise your platform a bit so it pushes plastic into the holes on the raft? You will have to cut it off the raft, but it won't lift.

An alternative, is to gently and carefully raise the raft a little with your fingers just as it prints the corner sections of the first raft layer - this achieves the same outcome.

Regards
David.

mec949
Posts: 123
Joined: Thu Jul 12, 2012 7:16 am
Location: NSW Australia

Re: lifting at the corners

Post by mec949 » Thu Nov 13, 2014 12:17 pm

To clarify, the raft is sticking to the perf board just fine, but the 90 degree corners are lifting off thecraft before the print completes.
Ideas?

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: lifting at the corners

Post by roller » Thu Nov 13, 2014 12:29 pm

Some prints a more prone to warping than others ... all ABS shrinks but its how those shrinking forces get spread through the print that causes all the issues with lifting corners. A consistent solution to reduce warping during printing is to use an enclosure which will hold the heat in and slow warping until the print has finished and hardened. There are 3 ways to do this: the quick hack - stick a box over your printer; the big hack - build a nice enclosure; the one use hack - add a set of walls to your print just outside the boundary of your problem print. The walls will trap heat around your print and it wont warp - essentially your printing a mini enclosure while you print your problem model. You often wont need the walls to be as tall as you print ... just the first 10mm will often keep the foot of the print adhered to the base.

There are other solutions too but these require changing your model, changing the orientation of your print but jsut holding in the heat with the enclosure requires less experience and understanding of what is going on.

mb20music
Posts: 375
Joined: Thu Feb 14, 2013 1:35 am
Location: USA

Re: lifting at the corners

Post by mb20music » Thu Nov 13, 2014 4:43 pm

Is the extruder fan air door completely closed? that usually helps prevent or reduce warping. A 40 mm cube is quite small and therefore you shouldn't need an enclosure with such a small print, I find the enclosures are really only needed for larger size prints or if the printer is in a cold room.

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: lifting at the corners

Post by roller » Sat Nov 15, 2014 12:35 am

I can make a 40mm cube warp off ... it can be due to the structure inside the cube ... certain designs will be prone to shrinking entirely in one direction.

mec949 .. forgot to say, make sure your bed is level. The later versions of software print with a thinner raft that may not be level by the time your print starts if your bed is out too much. The raft will stick because the bed heat stops it shrinking much but the weak layer for removing the raft will peel away too easily if contact is poor due to the bed being a little low that side ... once contact is poor it will warp away easily partly because of the weak mechanical connection and partly because the the heat will not conduct up from the base as readily making it cool faster and shrink even more.

stormychel
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Re: lifting at the corners

Post by stormychel » Sat Nov 15, 2014 10:41 am

I needed to print a few 120mmx60mmx25mm U-shaped profiles in ABS.

They had to lay flat on the bed because I needed the strength of the layers that way.

I have a 80° C heat bed switch soldered in place of the 60° C one.

What I learned from doing this :

- ABS slurry beats hairspray and glue stick
- Preheating 15 minutes is enough, I noticed no differences with 30, 45 or 60 minutes
- Closing the top opening (where the filament is routed in) is crucial, I printed something to close the gap
- Keeping extruder temp as low as possible is also beneficial
- Acetone wipe of the bead just after hitting print makes a slight difference

My parts are not perfect, and I had about 25% of totally unusable ones. The last ones that came out were usable enough, maybe a 0.5mm warp at the edges at maximum.
@stormychel

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: lifting at the corners

Post by roller » Thu Nov 20, 2014 1:40 pm

Stormychel ... they are useful tips for a raft lifting from the bed ... the OP issue is the main print lifting from the raft. The secet to which is to reduce the warp rather than increase the holding power.

mec949
Posts: 123
Joined: Thu Jul 12, 2012 7:16 am
Location: NSW Australia

Re: lifting at the corners

Post by mec949 » Sat Nov 22, 2014 4:35 am

Thanks for the tips guys
I moved the model so that it was more centered over the off center heating block

It worked enough to use the part

Now I just have to find a cheap enough heat gun/device to reset the colour after sanding : )

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: lifting at the corners

Post by roller » Sat Nov 22, 2014 11:22 am

I actally use a blowtorch style lighter I pick up in some dollar store for about $2.

mec949
Posts: 123
Joined: Thu Jul 12, 2012 7:16 am
Location: NSW Australia

Re: lifting at the corners

Post by mec949 » Sun Nov 23, 2014 2:47 am

Tried that, didnt give the result I was looking for, will see if I can borrow a heat gun and see how that goes.

roller
Posts: 1622
Joined: Sat Oct 06, 2012 9:09 pm
Location: Brisbane, Australia

Re: lifting at the corners

Post by roller » Sun Nov 23, 2014 5:59 am

Really? Maybe mines a little hotter than the average one. To be perfectly honest I have never ever tried another one - maybe I was just lucky with the model of lighter I picked up. Heat guns are a bit too imprecise (small section are easily melted) even with the fine nozzles and doesn't get into the recesses as well.

teamcarlisle
Posts: 180
Joined: Wed Jul 25, 2012 5:00 am

Re: lifting at the corners

Post by teamcarlisle » Sun Nov 23, 2014 9:54 pm

If you ever do soldering then I recommend one of these. This is the one I have, and the hot air re-working tool is perfect for getting rid of white spots from support removal and sanding (But if you get sandpaper dust/contamination in the plastic, it wont hide that)

http://www.amazon.com/gp/product/B00A2VQA24

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