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[Solved] How to safely insert magnets into a print?  

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TeachThePrints
(@teachtheprints)
Eminent Member
How to safely insert magnets into a print?

Hello,

I plan to print the following model and want to use the "pause at layer" feature to insert some neodym magnets in those holes, while the printer is pausing. The holes are 10.5 x 4mm to fit 10x3mm magnets. Is there anything to consider?

I am worried about:

 - the magnets not fitting easily, don't want to have to push them in risking the model lifting from bed.

 - the magnets clinging to the nozzle, while the solid layers above the magnets are being printed. Will the magnets jump out of the holes?

The magnets will be fully enclosed in the print.

Best Answer by TeachThePrints:

Found working parameters.

a) keep the bottomlayers thin, the magnets will want to stick to the magnetic bed countering the upward pull to the heatblock.

b) diamater of 10.1 or 10.2 are large enough to push the magnets easily in, while still ensuring enough of a press-fit to hold the magnets in.

With these settings, i can repeatedly move the extruder right over the magnets without having them jump to the heatblock.

This topic was modified 11 months ago by TeachThePrints
Standard Prusa Mini FW4.2.1, no enclosure...
Posted : 24/11/2020 11:16 pm
cwbullet
(@cwbullet)
Illustrious Member
RE: How to safely insert magnets into a print?

Enlarge the holes.  I used a drill bit.  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 24/11/2020 11:43 pm
TeachThePrints
(@teachtheprints)
Eminent Member
Topic starter answered:
RE: How to safely insert magnets into a print?

@cwbullet

It's a model I am making, so any dimensions are adjustable. No need to drill anything.

What I don't know however is, what the recommended size of those holes are.

I've printed models with press-fit holes before, where the magnets were inserted after the print finished. I'd use a wrench to push the magnets in. This probably won't be possible midprint without disturbing the print adhesion, so the holes will have be larger than the magnets. However, is there a too large hole?

Standard Prusa Mini FW4.2.1, no enclosure...
Posted : 25/11/2020 12:07 am
cwbullet
(@cwbullet)
Illustrious Member
RE: How to safely insert magnets into a print?

@teachtheprints

Not if the magnet is buried.  Too large of a hole would only be an issue the magnet drops out,  

--------------------
Chuck H
3D Printer Review Blog...
Posted : 25/11/2020 12:34 am
jsw
 jsw
(@jsw)
Noble Member
RE: How to safely insert magnets into a print?

I might suggest making a small test print.  I do this often for parts that have to fit together precisely.

If I were making a cavity for a 3mm (diameter) magnet, I would first measure the magnets with a good digital caliper to get the exact dimension and then make the hole maybe .1-.2mm (diameter) larger and do a test print for that.  When you get down to fractional millimeters, things like the width of the extrusion become significant, and I've found that test printing is a good way to see what works and to tweak the dimensions for the best fit.  I would want to get it to the point that the magnet requires a gentle push to get it in, but not enough that the plastic part will deform when inserting.

I like to have parts which fit together well, and I've found that test prints are very time-effective in doing that.

Posted : 25/11/2020 1:32 am
TeachThePrints
(@teachtheprints)
Eminent Member
Topic starter answered:
RE: How to safely insert magnets into a print?

There seems to be an issue, where the magnets are attracted to the heatblock. I've tested brass & steel nozzles, they don't make a difference. Even when the magnet is half a cm lower than the nozzle, it will get pulled up and cling to the heatblock. Do you guys glue the magnets in and wait long enough for the glue to dry before continuing the print?

This post was modified 11 months ago by TeachThePrints
Standard Prusa Mini FW4.2.1, no enclosure...
Posted : 25/11/2020 11:21 am
TeachThePrints
(@teachtheprints)
Eminent Member
Topic starter answered:
RE: How to safely insert magnets into a print?

Found working parameters.

a) keep the bottomlayers thin, the magnets will want to stick to the magnetic bed countering the upward pull to the heatblock.

b) diamater of 10.1 or 10.2 are large enough to push the magnets easily in, while still ensuring enough of a press-fit to hold the magnets in.

With these settings, i can repeatedly move the extruder right over the magnets without having them jump to the heatblock.

Standard Prusa Mini FW4.2.1, no enclosure...
Posted : 25/11/2020 12:53 pm
JustMe3D
(@justme3d)
Estimable Member
RE: How to safely insert magnets into a print?

Print yourself a 1mm high cap fitting on top of the magnet in the hole first. Insert the magnet, press the cap on top, flush to the surrounding surface, and the magnet won´t jump.

I try to give answers to the best of my ability, but I am not a 3D printing pro by any means, and anything you do you do at your own risk....
Posted : 25/11/2020 1:54 pm
Kalimero liked
loadinglevelone
(@loadinglevelone)
Trusted Member
RE: How to safely insert magnets into a print?

I've done prints like this tons of times. Never had a problem with the magnets getting "sucked out".
Just use a drop of CA glue then spray on CA activator and the glue dries instantly.
Oh and make sure the hole is a bit oversized so that the magnet drops in freely.

  1. Pause print.
  2. Add small drop of CA in the hole.
  3. Drop in the magnet.
  4. Add a squirt of activator.
  5. Resume Print.

 

This trick works even if the magnets are added to parts of the print which is far from the print bed.

This post was modified 11 months ago 4 times by loadinglevelone
My printers: Mk3s / Mk3s clone with +upgrdaes (you know SPinda and all that good stuff) / Mini+ / Ender 3 v2...
Posted : 25/11/2020 5:31 pm
3Dprintedgr
(@3dprintedgr)
Estimable Member
RE: How to safely insert magnets into a print?

Yeah exactly what I would do. Just add a drop of CA glue in the hole and the magnet will stay put until its covered by the layers above.

Original Prusa Mini + Smooth PEI
Prusa Slicer 2.2.0...
Posted : 26/11/2020 12:19 pm
Crawlerin
(@crawlerin)
Prominent Member
RE: How to safely insert magnets into a print?

Heater block is from aluminum and standard nozzle is brass. But screws holding heater cartridge or thermistor are from steel and may or may not be magnetic. Steel nozzle will also attract magnets.

Posted : 26/11/2020 3:14 pm
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