What is the best way to adhere an old printed part to the bed?

Question

I am currently trying to print a company logo on another part I have printed in a different colour. To try and maximise the strength of the part, I need to print the part on a different orientation to what I intend on printing the logo on. As a result I need to in a sense re-adhere the part to the bed so I can print the logo. I am using PLA filament on a spring steel sheet (the default sheet with a Prusa Mini).

Any ideas would be appreciated before I accept defeat and just glue the parts together.

Answer 1

I have not done this, but I believe this is the best method and I want to test it at some point soon:

Model a negative for the footprint of the part you want to adhere to the bed, in the orientation you want to adhere it, with just a few mm of height, and clearance suitable for your printer (probably around 0.25 mm) in the XY plane, and print that with thick extrusions on the initial layer so that it adheres well to your bed. It should look exactly like a "thickened brim" for the part you want to re-adhere. Don't let the bed cool after printing it.

Now, you have a slot to insert your part into that will not only hold it to the bed, but holds it to particular coordinates you chose to print at, which you can align to the coordinates of the new model you want to print on top of it.

If you can't get the clearances right to hold without knocking off the negative footprint from the bed, you could try adding some threaded holes to it, so that you can put a couple set screws through it to hold the part in place. This technique can also be used if you want to avoid modeling a full negative (e.g. if you don't have the original in CAD form where you can easily negative it) - just print a few posts to hold set screws in approximately the right places on the bed.

Answer 2

Adherence is the 3D printer's worst enemy.

I use painter's tape, but I heard that you can if you need to remove and re-stick it back, heat the part lightly with a lighter and re-stick it back to the bed. Never tried but I'm guessing you would need to cool the bed, heat the part, and stick it back then reheat the bed and continue to print.

Glue sticks can maybe help or even hot glue. But I would be afraid in that case that the part wouldn't be level hence the glue would be to tick.

Answer 3

I like the idea of printing a holder, for the part-it holds the part laterally and indexes the new printing. I would maybe model it and slice it separately. Then model and slice the text as a first layer thing. It is important the slicer doesn’t think the text is floating in the air, or it will interpret it as a bridge, and do weird stuff. Don’t use skirt or brim on text slicing. I’m thinking print the holder, keep the bed warm. Raise the extruder up out of the way. Get the plastic piece warm on the heated bed. Put glue stick on the part and stick it to the bed in the holder. With the extruder cold, slowly bring the extruder down until it is the right height to print, could use a sheet of paper between the part and the nozzle as a feeler gauge. Now the Z is at the right height. Bring up the text G-code. At the beginning of the G-code, edit the homing command, G28, to be G28 X Y, no Z, so it won’t home the Z-axis. Also, delete or comment out G29 auto-leveling if present. Then type in a line G92 Z.1, this spoofs the position of the Z-axis so the printer thinks it’s at zero plus the thickness of your sheet of paper (.1 mm). Add in a move to prime the nozzle, after it is heated M109, right before it starts moving. G1 E10 F400. Then G92 E0, then a retract move G1 E-2 F3900. This is right before it starts moving, with a long series of G1 commands. Note, ignore the prime, retract thing if your G-code already includes it. That should be good to print. Dial down the speed and be ready to catch the plastic squirt from the prime move with some tweezers, you could even hold something flat and metal under the nozzle as it primes to simulate having a surface to build up pressure. Immediately after the prime, be ready to micro-step the Z-axis to dial in your first layer as it starts printing on your part. Turn up the speed if everything is going to plan.

You could pull the filament out of the extruder and do a dry run if you’re worried about the part. Or print a couple in case the first one gets messed up.