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Tips/Techniques 3DP typical machine threads

Tips/Techniques
PeterT said:
Well that was painless. Used my 40W Weller with included tool. When I read ~185C I started feeding into 3DP. Went in slowly & predictably, maybe 3 secs? When it was ~ 0.5mm proud I flipped it over & pressed it on a flat surface to make it flush. Seems sufficiently strong for what I'm targeting it for right now. Maybe someone has done a gorilla test.
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A quick note on inserts you can design to put them on the back side of a part, instead of on the front. It makes for a lot stronger. To pull the threads you would have to pull right through the part. There are lots of ideas. I think I have a very similar kit to the one you ordered.
 
DavidR8 said:
Nice job.
If you need more strength orient the design such that the insert would have to be pulled through the part.
I plan to turn a few of those tips for various sizes.
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This 100%

I always orient my insert to be on the far side of the part so it would have to pull thru solid material rather than out of a pocket.
 
Yes I tried to explain that in my post but did a bad job. And showing the bolts threaded into top of inserts further confused matters. The 3DP test block was just to confirm the counterbore diameter & depth as per insert specs (big diameter on top side). Typically the bolt head would be on underside of sketch with shank extending through underside clearance hole into insert. So the barbs are mostly resisting torque & the counterbore ledge is mostly resisting axial force.

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I re-heated an existing threaded insert to remove it just for interest sake. It is obviously not getting full melt contact in the knurl. Not sure what do do about installation. It needs to be hot enough to insert slowly for control. Like maybe 2 seconds? Much slower (cooler) & it kind of sloughs material aside. Much faster (hotter) it can easily take an off axis trajectory or burn vs. melt. I know CA locks it in place. Maybe as good as it gets. They aren't gronk proof but actually pretty strong for what is pretty easy installation. I also tested an over-hole for slightly bolt, but you lose the amount of bottom ledge.
 

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I've been doing this wrong, or at least subsequently discovered a better method. Just rest the insert into pilot hole of 3DP, then engage the heated solder iron tip into insert. Plastic starts to melt quite soon as it comes to temp & you can better monitor infeed this way. I suggest leave insert proud ~1mm so you can press it flat & flush against some kind of datum. I was previously hanging the insert on solder tip until it got to a temp & then inserting = unnecessary juggling. I have also been wicking thin CA into the annular joint for good measure. It drinks a tiny bit, but I suspect the print will break or distort before the insert comes out tightening the threads. They are not Gronk proof by any means but sure are handy.
 
PeterT said:
Another useful insert/thread video with pullout test results (start ~ 7min)

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I haven't watched the video yet, but I hope it touches on the proper hole size for the insert. The manufacturer should state what hole size is best, but amazon vendors tend not to provide guidance. Your pic above suggested to me that there is not enough material to fill the grooves fully to lock the insert in place.
 
I'm glad you mentioned this. I obviously had a brain fart & was using the insert specs for my hole, not the suggested hole specs. OK, this makes sense now. Thanks!

ps - I learned a new trick where I can make a 'tool' (essentially a part model). Then position the tool with mates to my 3DP part & basically do a Boolean subtraction for the insert. That's pretty straightforward & might prevent some dummy errors if I keep a library of named inserts. But the tool could also have a counterbore/countersink profile which would allow me to simultaneously subtract material in assemblies in one go. Say like a screw through a lid into the part & even bolt over-hole clearance. Move or copy the screws & everything self-updates.

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www.amazon.ca

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The bolt head idea is a better way to finish pushing the insert the final 1mm (left proud when iron removed)/ That keeps the insert is as flush therefore perpendicular as possible. That's better than my flipping the part over on the table which may not even be an option. But a further advantage is the metal tool acts as a heat sink cooling the brass so the plastic solidifies as soon as possible. Now we are machinists, a ground holt head will never do. I propose turning a simple press tool from... aluminum for best heat transfer?

 
Amazon has tips with screw in sizes for each progressive insert. My insert set (arguably of the slightly better insert quality based on the video?) came with a tip so I dodged the bullet till I lose it. My tip is also made of brass which does the job for this purpose. Typically tips are copper but that's for soldering. My Weller is 1/4" nominal shank. I suspect these tips are 6mm but of no consequence. They are also hollow which I was kind of puzzled by, but maybe that mates with a different kind of iron with internal element?

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