HILLMAN CAR CLUB
OF SOUTH AUSTRALIA INC

Tech Tips: Mending Plastics
HILLMAN CAR CLUB
OF SOUTH AUSTRALIA INC



From: Keith Johnson [keiths55(at)bigpond.net.au]
Sent: Saturday, October 01, 2005 6:39 PM
To: HillmanCars@yahoogroups.com
Subject: Re: [HillmanCars] Re: EasiDrive transmission

Ken

Tip from somebody who often had the need to remove sticky stuff off expensive plastic equipment.

WD 40 or CRC 5-56 works wonders and doesn't harm most plastics or (so I am told:) the enviroment.  I think it smells good too :))

The other little tip is that the fibreglass rod from up the middle of some radio antennas is the most useful stuff to make various tools out of.  It works like a fingernail without damaging your recent manacure and is a very good insulator if you want to prod things with high voltage on them.

Keith



From: Kenneth Nelson [citbuff(at)sbcglobal.net]
Sent: Saturday, October 01, 2005 11:19 PM
To: HillmanCars@yahoogroups.com
Subject: Re: [HillmanCars] Re: EasiDrive transmission

You're right Keith about the WD40 I've never seen it affect anything except the dirt!  It must be a very weak solvent.  But the paint stripper really got after this ancient baked-on goo.  That plastic rod in the center of antennas is a material called "Delrin plastic".  It's made by Dupont I just retired from 35 yrs of working for them 27 of those here in Detroit with the auto co's.  Delrin has no glass fiber in it, so it will not scratch other materials, yet it is very hard for a plastic, an excellent low load bearing material, and resistant to all chemicals except acid there is NO glue for this plastic or nylons that's why nylon is the most extensively used plastic under the hood of a car it won't melt until it hits about 500 degrees F!
Delrin makes an excellent scraper for sensitive materials.  You can also make a lot of useful mechanical parts from it most windshield wiper and power window motor gears are made from Delrin or nylon (Dupont invented nylon in 1938).  If anyone on the list has a question on plastics, I'd be glad to help them understand the myriad different materials out there, and how to repair them.

Ken



From: Bernie MacIntyre [minxpei(at)yahoo.ca]
Sent: Monday, October 03, 2005 11:52 AM
To: hillmancars@yahoogroups.com
Subject: [HillmanCars] Plastics

Ken;
I hope you don't regret letting everyone know you have expertise in the world of plastics.  Like me, I expect most people are intrigued by plastics and have their own little plastic problem to be solved.  Here's mine.
I am trying to repair a large crack in a plastic steering column cover on my Hillman Minx.  The plastic is flexible shiny and slippery to the touch.  It reminds me of the plastic used in food containers such as ice cream tubs.  Is there any type of solvent or cement that will "weld" the crack.  I find that most cements won't adhere and will just peel off.  I would love to find something that works like the plastic model cement on plastic models.
Any ideas?
Bernie

From: Kenneth Nelson [citbuff(at)sbcglobal.net]
Sent: Monday, October 03, 2005 1:21 PM
To: HillmanCars@yahoogroups.com
Subject: Re: [HillmanCars] Plastics identification & repair

Bernie, here are some ways to first identify what plastic it is:  If the part has an area which is hidden, you can cut off a small piece just enough to hold in a pair of needlenose pliers and light with a cigarette lighter or some other flame.  If when burning it smells like burning hair, it's nylon.  If it smells like formaldehyde, it's acetal (Delrin).
Sniffing it carefully by wafting some of the odor toward your nose won't poison you just sniff gently, or snuf out the flame if it continues burning, and sniff the smoke.  If it smells like candle wax, it's polyethylene.  I suspect it is nylon or acetal if you say no solvent will touch it, and nothing sticks to it.  In that case, your best bet is to build a strong patch on the backside by roughing up the surface with medium sandpaper,smearing the area on both sides of the crack with a good epoxy, and laying fiberglass cloth across the crack and letting the resin cure.  If this still pops off, try going to a GM dealer or a NAPA auto parts store and getting some 3M superstrong bodyside molding tape, a thin foam (about 1/32 inch thick) doublestick tape, which will stick to just about anything.  Bridge the crack with this stuff, then peel off the backside protective layer, and put fiberglass cloth over the tape, sticking it to the tape, then put epoxy resin over that combination.  Let me know what works for you, and what your plastic smells like.

Ken



From: Bernie MacIntyre [minxpei(at)yahoo.ca]
Sent: Tuesday, October 11, 2005 10:21 AM
To: HillmanCars@yahoogroups.com
Subject: Re: [HillmanCars] Plastics identification & repair

Ken;
Finally got back to my plastic repair job.  I did as you suggested and clearly detected the paraffin odor and identified it as polyethelyne.  I thought I'd try my hand at some plastic welding now that I was able to identify the plastic.  I found another piece of same type plastic for a filler and heated up the 47W soldering iron.  On the back side, I melted a groove about 3/4 way through the plastic and melted in some of my filler plastic to fill up the groove.  Once both the filler and subject plastic were molten, I smoothed them together.  I continued this on along the five inch crack.  I am quite pleased with the result since it seems to be stable and strong.  I intend to repaint the piece with Krylon Fusion paint.  I have used this paint which is designed to adhere to plastics for my steering wheel and am very impressed with the way it adheres.  Thks for your help.
Bernie
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