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View Full Version : Nylon Thumb screws impossible to tighten/loosen


disaster999
06/10/2012, 10:12 PM
anyone have the problem where the nylon nuts on their skimmer, reactors, or any in sump products from avast? they went in smooth at first assembly but after a few months in the sump, it seems like the acrylic/pvc/nylon have swelled up and they are near impossible to tighten without the help of pliers. i feel like the more i turn the screws, it will just shear the head off leaving me stranded.

i thought of retapping the holes or getting stainless/titanium($$$) screws. would Justin please let us know what size thread you used so i can get the right tap? are there any other suggestion on how to free up these screws?

pyton
06/10/2012, 10:50 PM
should be 1/4 20 tap

ctenophore
06/12/2012, 09:10 PM
Yes, 1/4-20 is correct. The nylon does swell when submerged over time. You should be able to open up the threads by running the tap through to the largest portion of the taper. What do you need to do with the CS1 base screws often enough for this to be an issue? I've never really had to take the peglegs off of the one I use for testing. You can use 1" long 316SS screws as well.

psteeleb
06/25/2012, 01:10 PM
a little plumbers grease (100% silicon grease) goes a long way toward keeping the cap screws (and other threaded connections) easy to work

disaster999
07/06/2012, 01:14 AM
finally bought a 1/4-20 tap and going to try retapping the screws and see if that works.

since i was having a lot of problems with keeping my recirculating mod quiet i was taking apart and trying new things to quiet it down. would be nice to easily remove the thumb screw instead of rubbing the skin off my fingers trying to take it apart.

disaster999
07/06/2012, 11:24 PM
tapped out the holes last night and they are easier to tighten, i dont have to use my pliers. tapping the PVC peglegs didnt really help tho. tapping it helped a little, but still required me to use pliers to fully thread it in, might have to cut down the threads

Avast Marine
07/11/2012, 09:36 AM
Sorry for the late reply. The nylon screws are what are swelling, not the other plastic so retapping the plastic won't do a whole lot. Running the swollen screws through a 1/4-20 die will remove a bit of the swollen nylon and make them easier to thread.

jtma508
08/01/2012, 12:58 PM
I switched-out the thumbscrews for nylon screws with hex heads. I could never get them tight enough with just my fingers so needed to use pliers. Using a hex driver is alot easier and I can get them really tight without snapping the screws.

Want2BS8ed
08/02/2012, 04:59 AM
Hex heads and an Allen Wrench does sound easier.

Do you have a preferred source you can share?


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jtma508
08/08/2012, 06:35 AM
Not an allen wrench. Hex head so you'd want a nut driver of the appropriate size. I picked mine up at HomeDepot. Be sure to get them long enough so they pass through both flanges. That way, in the event that you shear one off, there is enough shaft to enable you to back it out. I found ones exactly as long as the originals: 1/4x20 1" by Crown Bolt.

zygote2k
10/28/2012, 06:30 AM
I find that if I shorten all of the nylon screws for the base by 1 threads, then silicone grease them, that they go in and come out much easier.

disaster999
10/29/2012, 04:08 AM
i actually cut the threads that thread into the peglegs shorter so i dont have to screw all the threads in. make it a whole lot easier to tighten and loosen