Don't let the bed size of your 3D printer stop you from printing larger items, Puzzle it!
Now it may seem simple and it is, but there are a few important steps to take before you start printing the first pieces of your new car ;-)
Update: 28 Dec 2018: See how I fixed a broken 3D printed conduit by using this technique, at the end of this instructable.
Step 1: Design and Print Test Pieces
Every material and printer needs a different gap size for the pieces to fit. My first set of puzzle pieces (to test the different % fill settings) did not fit at all, using PLA and my small Duplicator i3 Mini printer. I had no gap designed in and because of material flow during the printing stage (and the large effect it has on tiny details), did not fit at all.
I then went ahead and experimented a bit and printed 0.1mm gap pieces which was still not enough and no amount of pressure would make them fit. I also printed a set with a draft (sloped profile) but they didn't stick at all and would simply fall apart again.
For the second set I used a gap size of 0.2mm and that gave me a perfect fit which needed only a tiny amount of pressure to get the pieces to fit, enough so they would not simply fell apart again.
Disclaimer: The gap size needed won't be the same for larger puzzle tabs. The smaller the tabs, the bigger the effect of the printing and material flow error, while it may be less so for larger tabs.
Depending on the size differences, you may need to experiment for each size of tab to find its perfect gap size. But design the tabs into small test pieces - don't waste tons of filament just for testing.
I have added my 0.1mm and 0.2mm tests pieces (in STL format and one in STEP format if you want to make changes to it) so you can print them and test it with your material and printer to see which works best for you.
Step 2: (Optional) Add Connectors
For my tablet stand, the 3mm thick pieces did not allow for large puzzle tabs and super glue did not seem to be strong enough (or maybe I was just too impatient) but I then designed a personalized (why not?) connector that simply fitted into the holes to give extra strength to the connection (which I also super glued in just to be safe, although they did fit in stiff enough on their own without the glue).
The connector stubs was also designed from the start with a 0.2mm clearance (as determined with my test pieces) and fitted perfectly the first time.
Step 3: (Optional) Simple Connection
This step may have been obvious from the start, but here it is: The stand was designed so I can take it anywhere and therefore had to be flat when not in use to fit in my tablet case. For that I simply used this simple halfway groove technique (is there a formal term for it?) so the pieces would fit nice and tight when assembled but are very easily dissembled for travel.
And that's it! A tablet stand, large enough to hold my 10" tablet at an angle I always wanted, but too big to be printed on my little 3D printer.
Why buy a larger printer, if you can just puzzle it?
Enjoy new opportunities!
Step 4: Update: 28 Dec 2018 - Fixing a 3D Printed Conduit
The 3D printed conduit shown here broke (its a custom designed toilet extractor fan) but was too large for my little printer to print again and the design was probably flawed to start off with, so I decided to simply mend it with a custom printed connector.
Step 5: Printing Test Clamps
I decided to print the connector as 2 parts that could simply clip together around the broken conduit, but for the clips to work, I had to experiment a bit first.
The first clip design did not stay in place, so the decision to experiment first paid of, before I went ahead and printed both halves.
Step 6: Fitting the Pieces
The clips were not intended to be very strong, just to keep everything together while the glue dried.
That solved a few problems:
- It was not necessary to redesign or reprint the whole conduit.
- The installed parts was permanently glued (with Pratley Putty) to the fan and exhaust pipe which would have required a mayor operation to remove in a way the connected parts could be reused.
- The 2 connector pieces was small enough to print on my small 3D printer.
- The clips held everything nicely together while the glue cured for a permanent connection.
- The reason the conduit broke in the first place was due to the constant fan vibration and that area being the weakest. The connection made that area now stronger - so let' see where it will break next! ;-)
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