April 19, 2014 Login  


Epoxy, I love that stuff!
Last Post 01/13/2014 03:33 PM by 79 pmooney. 3 Replies.
Printer Friendly
Sort:
PrevPrev NextNext
You are not authorized to post a reply.
Author Messages
79pmooney

Posts:802

--
01/10/2014 05:06 PM
I am nearing the end of fabricating a dish drying tray to be suspended about 16” above the countertop. ¾” ply, varnished underneath, countertop laminate on top with oak trim pieces serving as gutters on three sides. It sits on a beam of madrone and there is a vertical to the ceiling of the same wooddas well. Finished product will be in three pieces bolted together (so when my dishrack dies and is no longer available, I can make a new tray to fit the new rack.)

Epoxy has been front and center in the construction of both the beam and the tray. Beam was fabricated from a 10’ piece of 1-3/4” square stock on sale at a high end woodworking store. I glued the pieces together to make a health 2x4. The oak trim was epoxied to the tray, then all but the bottom of the tray coated with epoxy before varnishing all but the top laminate surface. Laminate on with contact cement. Now I am carefully epoxying all the laminate edges with clear liquid. Final product will handle decades of water drip with no attention at all except cleaning when food build-up or mold becomes obnoxious and will clean up really easily. (I know this because I built a less fancy dish tray for my Seattle kitchen ~1993. It is still in fine shape.)

The real gifts of epoxy as I see it are: Water doesn’t affect it at all. It flows out as it sets, so with understanding of that flow, you can reliably get finished jobs that look beautiful. And you can work it like wood with sharp tools when it is set but not yet at final hardness. You have control over the setting times using heat.

I use the Gougeon Brothers WEST System boat building epoxy, stuff that has been around for decades. (And, un-mixed, an opened can of it can sit around for another decade or two and still be as good as new.) Their pumps make the critical issue of correct proportions of resin and hardener easy. And they have two hardeners, fast and slow for cool temps and/or faster curing times and slow for warm temps and/or longer working time. The slow also is clear. The fast is purple so they are very easy to tell apart..

I also use Marine Tex, a very strong epoxy that flows very little on setting, often first, then putting a light coat of fiberglass and WEST System over to make a nice smooth finish. Never saw anyone recommending that procedure but I have been doing it for years and it works.

And to get to bike applications: well, there is Team Dumpster, saved from the dumpster with a carbon fiber wrap from an inch up down and seat tubes, fully around the BB and out the chainstays well past the gusset. (Each chainstay was about to break, with cracks going around 2/3s of the right and 1/3 of the left immediately behind the gusset.) I also have done uncounted little epoxy jobs over the years.

Next project is coming up soon. This one I want to make look really professional. My new ti fixie, Jessica J, uses fenders for the winter. But the rear fender is a challenge, both fitting it and not having it breaking. The problem is that I slide the rear wheel close to two inches in use. If you take a standard plastic rear fender and pull the back two inches, it changes overall shape, coming down at the top and the sides wanting to flare out and break. Some of this gets helped when I cut the fender forward at the brake bridge and make brackets for each half. But the rear half still has issues unless I am willing to let it sit very high over the top of the wheel. The first fender got cut, modified, and bent so many times it started to break. Did an ugly repair with a patch of CF I had. Went out and bought new fenders. This time I will cut the rear as before in front of the brake bridge, then cut slices into the rear piece in two places between the top stays and the brake bridge. These cuts will be through the flange of the fender, say 1/4” and end at a drilled hole (to prevent a crack from running from one side to the other). This will allow me to straighten the fender at those points without stressing it. Then I will mount the fender, bend and support the fender to form a roughly straight line between those top stays and the brake bridge. Hang the bike upside down, no rear wheel. Last I will butter the stay brackets with Marine Tex, then cover them and the two areas with the slots with say 3” rectangles of CF. Trim the fender edges neatly with a trim knife when that magic time comes. Next day, flip the bike over, replace the wheel and enjoy a rear fender that looks right, should last far longer than stock, go on and off easily and work really well with this sliding wheel.

I want two things from this end result. Ease of changing cogs on the road between 23 teeth and 12 without fussing with the fender to keep a 25c tire from rubbing (I may well be doing this in January in the rain) and good looks, fitting for the fine woman Jessica J is.

Ben
THE SKINNY

Posts:233

--
01/10/2014 05:52 PM
where would the world be without the Gougeon Brothers? i built a cedar strip canoe several years ago and epoxy was a major ingredient. that stuff takes some skill to work with. i think i sanded off more than i put down due to inexperience working with it. the fumes make me queasy even though it really doesn't smell bad. it does make a nice durable and good looking finish. i read that epoxy and oak don't work well together due to discoloration but i recently used it on some oak seat rails for the canoe (i'm to cheap to go buy ash when i have scraps of oak lying around). so far they look presentable. have you got pics of the dish drying tray?
How we spend our days is, of course, how we spend our lives.
79pmooney

Posts:802

--
01/10/2014 07:24 PM
I guess when I arrive at the pearly gates, I may be sent back for discoloration, but 'til then, I seem to get along quite nicely mixing oak and epoxy. Ignorance is bliss!

Ben
79pmooney

Posts:802

--
01/13/2014 03:33 PM
I am now making two molds for my new rear fixie fender to support the fender shape after I epoxy the CF onto the underside of the fender at the bends and at the stay brackets. Two because the fender will have a "valley" at the bend. Each mold will be 3-4 inches long and will be placed end to end meeting at the valley.

I will first tape the molds securely in place. Then I will epoxy in the CF. Finally, before teh epoxy sets up, I will lay plastic over the CF/epoxy, then old socks, etc. over that. Then I will wrap all with innertubes cut into strips. This will apply uniform pressure on the CF, squeeze out excess resin and simulate a vacuum bag.

I will have to see how well my molds turn out. If I can crank out 8 of them, I can do all of the epoxying in fell swoop. That will speed things up a lot since I am going to do at least 5 on this fender. (Two bends, two stay brackets and the bracket I am making at the brake bridge. I will do a similar, though simpler job on the tab I made to fit the chainstay gusset.

Kinda funny ... I am going all this to make fenders that will last as close to forever as I can do, then cut an oval out of the forward piece of the rear fender at the seatstay so that , at the closest point, the tire sees no fender at all. In low gear, 43 x 23 with a 25c tire, the tire is VERY close to the seattube.) But that piece of fender is short, doesn't vibrate at all and I don't see that the cutout will make much of a difference for longevity. The big rear piece, with all the help I am giving it, will still be the first to go.

Now to go back and see if my placter has set up and also start cutting/shaping the next part of the fender, at the brake bridge..

Ben
You are not authorized to post a reply.

Active Forums 4.1

Latest Forum Posts
Guess he's gotta make a living... posted in The Dark Side

Interesting book posted in The Coffee Shop


PR: d'OH! posted in The Dark Side

Do you ride by miles or time? posted in The Coffee Shop

Amstel Gold - who have you got posted in Professional Racing

A tough read. Literally, the dark side posted in The Coffee Shop

No articles match criteria.
  Terms and Conditions | Privacy Policy  Copyright 2008-2013 by VeloNation LLC