Printing PETG over a CrMo steel insert
Hi,
I would like to print an element using PETG (100% infill) , but have it reinforced by 3mm thick 90mm diameter steel core.
I could print it with normally (with supports) , remove the supports, insert the steel core, try to bond both somehow (glue?)
Before I do that I'd like to explore the possibility to lay PETG on top of steel core.
The plan is to:
1) print the initial layers up to 3mm height. The outline printed will have empty space to accommodate the steel core
2) place the steel element on the print bed. It's top surface will be flush with what's already printed.
3) resume printing - first remaining layer will get placed on top of both PETG and the steel core.
I'd like to use your experience to help me with following questions:
How likely it is the PETG to stick to the surface? (it's grooved = machined but not polished)
Do I need to prepare the surface of the steel element in any special way?
Do I need to heat the steel core?
I plan to use PETG because the part will be mechanically stressed and used outside. PLA is out of the question, but maybe other filaments?
Any other questions I need to ask?
Thanks.
RE: Printing PETG over a CrMo steel insert
I have put steel rods and nuts in prints. You do not need to prepare them in any way.
Nylon and PC blend are other options.
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Chuck H
3D Printer Review Blog
RE: Printing PETG over a CrMo steel insert
Just a small addition, because it has not been stated per-se:
I would like to permanently embed/connect the metal insert within printed part (it will act like a reinforcement).
Stronger the bond the better.
--
Michal
RE: Printing PETG over a CrMo steel insert
Hi Michal.
when I need a solid piece, I use lots of top and bottom layers and that leaves no space for infill.
it might be worth you considering additional perimeters.
Please be aware that large solid 3D prints are likely to distort. so you may well find an enclosure beneficial
enclosures don't need to be expensive setups, to try the idea out, you could simply put a cardboard box over the printer!
maybe add a cling film window (held in place with duct tape or similar... ) to prevent the 'Schrodingers cat' situation where you can hear the printer running, but you don't know whether it's printing successfully or simply causing a megablob of doom.
What format are your inserts going to be? 90mm plain disc? 90mm washer? 90mm threaded insert? 90mm retaining ring with many plain or threaded holes?
Is the metal likely to corrode inside the printed part? (I don't know about ChroMo) if so surface treatment may be beneficial, rustless steel inserts may be a cost effective alternative!
how much extra space are you going to leave inside the model to allow for the part. maybe 0,5mm extra on the diameter and 0.25 extra, on the height.
the printer should consider the area above the insert as a bridge, so it is not expecting to print directly on the insert. But if there are holes in the model, over the insert, you may find that the bridge is difficult to print well. in this case, say the insert is a simple washer with a concentric hole, design the model so that it has a single solid layer across the top of the hole, so that the bridging can work well... it should be easy to remove the single layer, after the print completes. it is unlikely that the filament will bond successfully with the insert.
If you have space on the build plate, it may be worthwhile placing the insert on the build plate to warm up as the model approaches insertion height, otherwise heating the insert to build plate temperature would probably be beneficial, before insertion... (don't forget to use gloves or tools to handle the insert!)
if your insert has multiple holes or eccentric holes it may be beneficial to either use one of the holes as a locating index and create a suitable lump on the base of the hole, to register the insert when it is added, so that your holes line up with the final model...
If your model has through holes, through the insert and below the insert in the model, you may be able to add a removable peg to align the insert with the features below whilst you print over the top of the insert.
hopefully the attached file will demonstrate where i added magnets to a badge that I made, using the add pause facility in Prusa Slicer... I also added manual colourchange.
I hope this helps,
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: Printing PETG over a CrMo steel insert
Your steel core will not stick to the PETG printed part - if you want so you have to try new ideas - on your own risk. Is there a 2 component resin / glue available to stick to PETG. If so, you could do it in the way you described, but before puting in the steel core you have to cover the surface with resin, then put it in and clean the surface from resin / glue. Could be a way. Needs someone to try it out.
Best regards, Clemens
Mini, i3 MK2.5S, i3 MK4, CClone (Eigenbau)
RE: Printing PETG over a CrMo steel insert
Do you have an image of what you want to do? I might not fully understand.
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Chuck H
3D Printer Review Blog
RE: Printing PETG over a CrMo steel insert
Here is the central element - the print will fit the outside shape, (tightly wrapping the cog teeth) and small concentric holes to provide for best transfer of force.
Adhesion to the top surface is what I am after.
Thank you all for your suggestions so far.
Michal
RE: Printing PETG over a CrMo steel insert
How thick will the PETG be covering the teeth?
I see you have a bunch of holes, couldn't you print in 2 parts and bolt together?
RE: Printing PETG over a CrMo steel insert
The big outside diameter will be 170mm, thickness of the part will change from 3mm at outer edge down to 13 mm in the centre.
So PETG covering the centre will be 13mm.
I could attempt to use glue, or simply thread some of the holes and use bolts.
Before all that, the most efficient way would be to use the benefits of additive manufacturing and 'submerge' the central core in the plastic