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View Full Version : What temperature will the plastic parts on an STG withstand?


armedpeasant
June 16, 2002, 19:01
I'm refinishing one my STG with Norrell's moly resin, and I would like to do the knob on the cocking handle at the same time. Moly resin needs to be cured at 300 degrees F for one hour. Will the plastic on the STG withstand that type of curing? I think that plastic painted with moly resin can be cured at a lower temp, but I'd rather cure the cocking handle at the correct temperature for metal, since it is a part that sees some friction wear.

Alternatively, how do I get the knob off the cocking handle? I've removed the pins from the handle, but the knob won't come off.

Nicco
June 16, 2002, 19:16
Can't help you with the rest but the cocking handle knob is rivited on and to remove the old rivit must be drilled out.

armedpeasant
June 16, 2002, 19:47
Well, looks like the knob will be staying on, then.

armedpeasant
June 16, 2002, 21:33
For anyone who is interested, I have had the carrying handle and the cocking handle in the oven for close to an hour at 300 degrees F, and they seem to be holding up fine, even though a portion of the carrying handle has turned a darker color.

cliffy109
July 08, 2003, 17:58
I can attest to the fact that the knob on the DSA aluminum charging handle can not withstand an hour at 300 degrees. I'm fairly distressed at this fact as I now have a pretty glob of hardened goo at the end of my charging handle. I'm pretty sure I will not be able to clean this up in any satisfactory manner so I will probably need to buy a new charging handle.

Radio
July 09, 2003, 00:52
Here is a complete reprint from a post just over a week ago. Material from my personal archives.

Topic: Temperature limits of plastic furniture

JRTex
March 09, 2001 23:21
I just got done curing a pistol grip and Penguin Humpback stock in the oven at 250 degrees, pistol grip for about an hour and the stock for 40 minutes. They did not soften at all.

gunplumber
March 10, 2001 23:01
* Bakelite: 300 F (1 hour)
* Pistol grips: 300 F (1 hour)
* Hines grips: 300 F (1 hour; hang - no metal to plastic contact)
* Original StG cocking handle: 300 F (1 hour; may crack but won't melt)
* Original StG cocking handle: 200 F (won't crack)
* DSA latest cocking handle: melts easy - dont have a specific temperature but it can handle 190 F park
* StG carry handle: melts somewhere around 250 F
* Izzy carry handle: 300 F (1 hour)
* Inch handguards: 300 F (1 hour)
* Inch carry hadle: 300 F (1 hour)
* Inch pistol grip: 300 F (1 hour)
* Inch stocks: 300 F (can handle temperature, but yellow foam expands)

ER
March 10, 2001 23:12
Most polyethylenes and ABS's will start to noticeably soften at 375 F, most nylons at about 450 F. These materials process at lower temperatures due to the shear heat induced in them by the extruder screws, gear pumps, or injection rams and nozzles used in the manufacturing process. I design polymer processing equipment, so if anyone knows the exact material used in the plastic furniture, I can give you a pretty good ballpark estimate of the maximum temperature it will withstand without softening. Different additives, such as anti-aging solutions, solvents for lower process viscosity, color additives, etc, will affect the temperature characteristics of the finished product.

Stick with gunplumber's temperatures and you will be good to go.

********************

Maybe I've found something else I like about those aluminum G1 charging handle knobs.

--Radio

msnyder
July 09, 2003, 11:14
I melted my stg-58 at 300F while curing my Moly Resin finish.

huntnfish
July 09, 2003, 17:07
This is from fireflys website

Curing Procedures: All Metals
After part(s) are coated with Moly ResinÔ they should be cured in the oven
at 300 f. for one hour. If you prefer, the temperature may be reduced to
250 f. and cured for 1 ½ to 2 hours instead of one hour at 300 f. The 300
f. curing temperature does produce the hardest coating.