GTA
All Springer/NP/PCP Air Gun Discussion General => Machine Shop Talk & AG Parts Machining => Topic started by: condor22 on May 08, 2018, 11:44:45 AM
-
I have to install plastic parts using machine threaded bolts where oem screw threads were sheet metal course threads. Sometimes these parts are old and brittle and non available replacement parts.
My question is should I rethread to machine threads or just chance breaking something with the new fine thread screws. I make my own taps using a machine screw with three slots dremeled on the tip of a fine threaded screw like the ones I have to convert to. These work fine in aluminum when the threads aren't deep enough or damaged.
Some times the plastic screw holes are cracked and break upon installing the machine screws. Would tapping these to machine threads before installing and applying super glue save these parts as from experience these typically break causing headaches?
-
See no reason why not ... If your attempting salvage one must do any tricks available. Sometimes thinking outside the box and coming too SIMPLE & unique solutions becomes the best course.
In such thin plastics, too much stress breaks them further ... so minimal stress and an adhesive seems like a very good idea.
-
Condor22,
What about t-nuts or a bolt with a support washer from behind? The ones with the spikes are more common buy you can break or grind them off.
A plastic epoxy may work better as super glue doesn't work on some plastics.
You could also use a JB Weld type product to build up the plastic and re thread.
Thanks,
Taso
-
These are plastic trim pieces that the screws can't go through. The t-nuts would be a life saver if I could use them. My supervisor rebuilds the broken threaded posts with epoxy with some success.
If I have all the broken pieces. I don't have anyway of drilling another hole. Thanks
Sam :)
-
Do you have a picture to share of what you're working with?
Thanks,
Taso
-
I can't post pictures from work. Basically it is a plastic post with a threaded hole through the center bout an 1/8in thick. These are hollow plastic trim pieces that mount to the metal doors and covers. This trim takes the brunt of all knocks and scrapes and door slams. Requiring removal, painting and reinstalling for a good looking refurbish. The covers, door and trim are painted as to look new.
-
I have used this stuff in the past to repair plastic motorcycle parts. It works a lot better than superglue:
http://www.plastex.net/Repaired_Photos.php (http://www.plastex.net/Repaired_Photos.php)
It comes in multiple colors.
If the plastic part has any value, I'd buy some real taps as they would work better than a grooved bolt. Get a cheap Harbor Freight SAE or metric tap/die set for under $16.
-
I have used this stuff in the past to repair plastic motorcycle parts. It works a lot better than superglue:
http://www.plastex.net/Repaired_Photos.php (http://www.plastex.net/Repaired_Photos.php)
It comes in multiple colors.
If the plastic part has any value, I'd buy some real taps as they would work better than a grooved bolt. Get a cheap Harbor Freight SAE or metric tap/die set for under $16.
Thanks I'll make some suggestions. ;)