Is there a secret to getting nuts into the nut traps?

First time poster so excuse me if this has been asked before; I used the search but it yielded many hundreds of posts for "nut trap." Anyway I'm building my first mini-Kossel and I'm having a difficult time getting those nylock nuts to stay firmly inside the nut traps. The build guides say just thread a screw in and pull, which sounds easy, but maybe my prints have bad tolerance because even when using a claw hammmer for leverage as soon as you touch those nuts they pop right back out. Filing the nut traps isn't an option on the effector because it's so enclosed I couldn't get a knife in there unless the knife curved a complete 90 degrees at the tip. I've heard of people using heat guns to expand the part, but I'm wondering if that is with minor fit problems only. I did try heating up the ABS by running under 90 degree C water, but it did not help at all.

Any advice would be appreciated.

Edited 1 time(s). Last edit at 11/18/2014 05:18PM by Rett Mikhal.

Fire? Heat the nut with fire?

That is my answer if i am understanding your question right.

I use a sodering iron to heat up the nut and push in

I see so you suggest heating the metal so it melts the ABS on contact. Interesting, none of the guides said such an operation was necessary, which led me to believe the nut trap would have a press fit clearance that could be easily installed.

I'd say bad tolerance. On my Mendel90 kit, I had a few nuts that could be pulled/pushed in with a little extra pressure, or were just loosely inside the trap.. but never so tight that they wouldn't go in right or pop out.

The nut manufactererers tolerance can vary and still be called a standard nut.
Countries of production and even factories will have slight different sizes on the outside dimensions

I'm not sure that's an option for me, however, as this design requires nylock nuts to be inserted into the traps. Heating up the nylock would most likely damage it.

I may just throw some delicious locktite in there.

Did you print the part?
Or you bought a kit?

Did you allow for shinkage for your printed part?
I print at 1.05% the size to allow for shinking.

If you designed the part. You may be able to scale the insert hole only.

Or file down the nut faces?

You should tell your kit supplier to build one of his own kits. Faced with such a situation I would use a soldering iron placed against the nut to melt the abs. The plastic in the nyloc nuts melts at a higher temperature. If you have a temperature controller on the soldering iron then you can set it a little below the nylon melting point.

I often use a pair of multigrips to squeeze a nut into a nut trap. I'm not fond of heat as you can easily end up with a misaligned nut.

---

[3DKarma.com] - suppliers of quality, affordable 3D printer kits and filament for the UK market.

It is from a kit. I haven't heard other uses complain about this problem, so it's possible it's the hardware (maybe also in combination with tolerance and shrinkage). I have the 3D files and I am going to modify them as I build for a second, easier build. I use SolidWorks.

I will try the heating element idea.

I sometimes use a longer bolt and force the nut into place just by screwing it on - making sure its shape is aligned with its hexagonal hole.

This is a good test to see if the printed part is strong too, so be cautious, use large washers, etc.

---

Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

I'm not sure if I'm relieved or dissapointed that no one posted any jokes.....

"Too many funny words.......weiners......." - Kevin from Rifftrax's 'This is Hormel' short.

Yes I'm warped, why do you ask?????

Soften the traps with a hair dryer or heat gun. Make sure you don't damage the parts by leaving them exposed too long. One way to use heat is to incorporate the screw through the nut as noted above and use the screw to push or pull the part into the trap. Once the nut is in the trap, wait a few seconds for it to cool then unscrew the screw. You could also try heating the nut with a hair dryer or heat gunand using the screw method to insert it into the plastic. I mostly heat the parts then insert the hardware or bearings but you can heat the parts and insert them that way.

With ABS i put a drop of aceton in the trap, after a few seconds you can press the nut in. Make sure to align the nut correctly while the ABS is soft. After the aceton is evaporated you have a tight grip.

---

[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

Quote
Rett Mikhal
I'm not sure that's an option for me, however, as this design requires nylock nuts to be inserted into the traps. Heating up the nylock would most likely damage it.

I may just throw some delicious locktite in there.

Loctite will ruin ABS, makes it become brittle and fall apart. I'd also not use lock nuts, if they get in the trap and then spin you are pretty much screwed out of recovering the piece. A standard nut with superglue to hold it will be fine, I doubt you would even need the superglue unless the trap is really bad.