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Old 12-29-2012, 11:14 AM   #283
therivermonster OP
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Location: Tacoma, WA
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Custom Hand Guard Deflectors...

Project #6: Carbon Fiber Hanguard Deflectors - Part 1

I have started in ernest on Zoomzu's handguard deflectors for his KLR. He is running the Moose bark busters I think, or the ones that you can get at ProCycle. He purchased the kit without deflectors, so he's in need of something to keep his hands toasty. No worries, Mike. I've got you covered.

These are the guards that the deflectors will be designed for.






I have spent the last few days pondering how I would design, and build these parts. I could have made a splash mold from the deflectors that I have on the DR and then just lay up the parts from there, but where's the fun and originality in that, right? Also, I wouldn't really learn much by doing it that way. With this in mind I figured what the heck; I may as well build these things from the ground up and make them my own, so I got started...

First I traced the profile of Zooms bark buster bar onto a piece of cardboard. From there, I cut the cardboard template out and traced it onto a piece of 3/4" birch ply and cut the left and right side solid templates from the ply with a jig saw. (no pics)

Next, I used the paper template to mark the shape onto 1.5" closed cell foam insulation from HD. I used the jig saw to cut out 4 pieces for both sides. (no pics)

Earling had reported in one of his threads that he had good success using Weldwood contact cement (in the green can because it's water based and won't melt the foam) to glue foam together, so I used it too. (picture. Yay!)


With all the pieces cut, I brushed the contact cement onto the appropriate surfaces of foam and wood and stacked everything together.


After both left and right hand stacks were compleated, I placed a board on top and added some weight. Now they are left for the glue to dry.


While I was making a mess, I figured that I would take some 60 grit sand paper to a piece of scrap foam to see how it shapes. It shapes nicely with just the sandpaper which gives me confidance about getting a good design on the deflectors.


After the glue sets up, I'll make a paper template for the front side of the deflectors, then trace this onto the foam stacks. Once traced, I'll cut out the rough profile of the part as seen from the front. From there, it'll be sanding and shaping. Probably a bit of Bondo and fiberglass to get things solid and smoothed out. Once the basic shape is there, I'll use Apoxy Sculpt to create the hard features of the part. Once the design and shaping is finished, I'll apply Duratech 2k high build primer to the part. Do the finish sanding and then the best part. Duratech 2k primer is a polyester product that is able to be sanded like primer, but you can also polish it to a very high sheen to get a grade A plug surface. Nice and shiney. Keep in mind that once this is done, we have only just finished the plug. Now we'll have to add flanges, lay up the molds, prep the cured molds, and then finally make the parts. Once the parts are layed up and cured, they'll have to be trimmed, sanded, UV clear applied and then polished.

That's how it'd done, people, but I bet that these things are going to turn out awesome, and they'll be the only ones like em out there. Not to mention that they'll be shiney carbon fiber, unitl Mike crashes anyway. The good news is that when they do get scratched up a fair amount, Mike will be able to sand them out and spray on new clear. Wala. Just like new.

A note about the layup schedule. The final parts will probably be layed up with the following schedule for durability and safety.
2 layers 3K 5.7oz 2x2 twill carbon
2 layers of 5oz plain weave Kevelar
2 layers 3K 5.7oz 2x2 twill carbon

This should provide a fairly lighweight part that is strong and won't splinter upon impact due to the Kevelar.

I started to shape the the parts out of the foam, but it just wasn't working the way that I had hoped, so I cut the foam from the plywood forms and sprayed acetone on the foam that was stuck to the plywood to disolve it. I scraped the disolved foam off with a plastic squeege.


The disolved foam is nasty stuff. You probably wouldn't want to mess around with it too much..


Now I am in the process of deciding how I am going to go about shaping the plugs again. We're back at square one so to speak, but I have a few ideas in mind.

I also needed to solve another problem. Because I am using a piece of plywood as a template in this project, and because the plug needs to be created above and below the broad surface of the plywood, I figured that it might be wise to create some sort of work stand to hold the plywood up off the workbench. To do this, I simply laid down a strip of plywood that I had, hot glued two 6ish chunks of 2x4 to the plywood base, then screwed the plywood templates to the end of the 2x4s. This has been working out well so far.

I decided that it would be best if I only cut just as much foam as I need. The foam doesn't need to cover the whole surface of the plywood template. Here you can see the first piece of foam glued down to the new work stand.


Next I cut another piece of foam and glued it ontop of the existing one. I set this one back a bit in order to save some time shaping.


After all four pieces of foam were glued up, I got to working on the shaping part of this project.


I picked up a few tools for shaping at Home Depot, and this one has proven to be very useful for this purpose. You can find it where you would find files, and similar tools.


After I had given the foam blocks a rough shape, I marked the lines where I would cut to bring the plug down to the middle mating line.




A wood sawsall blade and quick trimming with a razor knife give new deffinition to the shape. They don't look quite like hand guard shrouds yet, but I think that's because the bottom half isn't there yet.





The time had come to glue up the foam pieces that would make up the bottom half of the part. After cutting out the pieces with the jig saw, I simply unscrewed the ply templates from the 2x4s, flipped it over and screwed them back on. Then I brushed the Weldwood on and got busy constructing.




I needed to give a rough shape to the bottom half of the deflectors, so I marked a line that I though would look good and cut off the wast with a sawsall blade.


Now that the top and bottom were glued up and roughly cut out, I had no further excuses not to get along with the final shaping. The following pictures show how that process progressed.






And the semi-final finished shape. The black marker lines represent the trim lines on the final parts. Of course the parts can be trimmed more if a different shape or style is required.


Next, I'll need to do just a little finish sanding/shaping on the foam. Once everything is semi smooth, I'll lay down a couple layers of 8oz glass and epoxy to make a nice durable, hard, sandable surface in which to do the final fairing (finishing) with Bondo followed by a couple coats of Duratech which is a 2k polyester high build primer that can be sanded and polished to a high shine. I want this mold to be grade A with flanges in the 6" range to make it easy to use for infusion.


The time had come to move on to the next step in the process. I had gotten the foam to a shape that was accetable, and looked something like a hand guard. Now I needed to brush on some epoxy and add a layer of epoxy.

Here I changed the mounting of the guards from horizontal to vertical.


Next, I mixed up some 635 thin epoxy and brushed it onto both of the foam shapes. If you are doing this yourself, keep in mind that polyester resin will eat the foam. Epoxy resin is fine though.


After the epoxy set up a bit, I layed down a layer of 2x2 8oz fiberglass cloth on both plugs.




The temps have been in the low 30s, high 20 outside lately, with the shop hovering somewhere around 60f, so I kept the forms under the heat lamps for a couple of days. This helped the resin set up nicely, creating a nice hard surface.


Laying the fiberglass was the last operation that I needed to do with the plywood and 2x4 stand, so I marked the plugs with a trim line so that I could trim off the excess plywood on the back side.


I had been comtemplating purchasing a multi tool to trim molds and parts with, and after I had done my research I setteled on the Fein Multimaster. I have only had the oppertunity to use the tool a couple of times so far, but it is awesome. For more info about the tool, click here. I bought the starter kit at HomeDepot for $200 because I don't need all the scrapers and sanding pads that the other kits come with, but Fein does offer a number of kits to get you started.

Here you can see the tool resting on the 2x4 just after making quick work of trimming the plywood tab off the back of the form.


After I trimmed both plugs, I did a quick bit of sanding on them to remove any sharp fiberglass points. Here are the set. They kind of look like a bra when they're together like that.





The surface is now nice and hard which will make it easier to sand and finish.

Now I needed to reslove the issue of how I was going to mount the plugs in order to create a platform to build the mold from. I had a piece of MDF covered in some sort of laminant, so I decided that I would mount both plugs to it and create one mold with both plugs included in the layup. I wanted large flanges, and after setting the plugs on the piece of wood, it looked like it would work out perfectly.

Here you can see the two plugs mounted to the base. They are screwed from the other side.


Next I scraped on some Bondo. When it dries I'll sand the forms smooth, then add material to fair out from the high edges of the plugs down to the board. I may use foam covered with bondo, or I may use clay. I'm just not sure yet.


After applying the Bondo, I set the contraption under the heat lamps to provide some heat to help cure the bondo.


After the Bondo set up, I got down to sanding. I'm sure you've noticed the posts in the thread how best to sand down Bondo. It isn't the hardest stuff, but it's not the softest eathier. If you're a Bondo amature like me, make sure to take notes on those useful tools.

Here, I have sanded the plugs smooth again. They are really smooth now.




I needed to put the final primer/surface layer on the plugs and decided to go with Duratech poly 2K high build primer. This is the first time that I have ever used this stuff, and after this experience I am hooked. It is awesome stuff.

The materials needed are the Duratech primer, MEXP which is the catalyst for the primer, a brush, a mixing stick, and a tub to mix it in. You'll also need a good respirator because this stuff will mess you up if you breath it. After applying the Duratech I left the shop/garage. You could smell the MEKP very well from outside of the garage and it is very nasty smelling stuff. BTW, this stuff is made especially for finishing plugs in preperation for mold making.


I made a little test drip on a piece of foam I had laying around. Here is what happened.

Maybe 10 seconds after application.


10 minutes after application.


12 hours after application.


This stuff will mess your foam up if you apply it directly to the foam. Don't do that.

I was going to make a smart decision and have my buddy Mike spray the Duratech for me, but I decided to be impatiant and brush it on myself. (Hey, they say you can brush it on. Don't give me a hard time.) This worked OK in the end, but it would have been much easier, and I would have gotten better results if I had sprayed it.

The brush strokes are very visable, but the material doesn't sag mugh. You brush it on and it just sits there. That's what I like to see. Thanks, Duratech!


Due to outside temps, the heat lamps came back on for the duration of the cure.


The Duratech has dried, so back out with the sanding paper. I hit thses things with 60 grit for a good 2.5 hours to get them smooth. You see, the ridges created by the brush strokes caused lots of high spots. If you do it, make sure you spray it. I know I will next time.


Here the left plug has been sanded down to 250 grit, and I have started in wet sanding with 800 grit on the right one. Lots of sanding and prep work.


From 800 grit, I wet sanded 1000, 1500, 2000, buffed with compound and then polished. The 60 grit paper made some very deep scratches that I didn't feel like going after, and I though that this was going to make the plugs rougher than I would have wanted, but they are actually very smooth. I'm sure that they'll make due as good plugs.




Now I need to add flanges, wax, and lay up some nice quality molds.


For flanges, I decided to screw the two plugs closer together on the board, build up to the parting line with foam and clay, and call it good. Inmate Zoomzu stopped by to lend a hand. Thanks for the help, Mike! I hope you enjoy your hand guards once they are finished.

We got to cutting foam and gluing it to the board with hot glue. This allowed us to fill in most of the space above the board with cheap foam before adding the clay.


As we worked our way around, we started to add clay. We used KleenKlay which is a non drying modeling type clay meant for this use. You can pick it up at USComposites, or other composites retailers.

Here we have started to add the clay.


All you have to do is pull chunks of clay off, and spread it onto the foam and up to the parting line of the plugs. The clay makes a nice transition from the plug to the flange which is actually made out of clay in this instance.


Thanks, Zoom!


Finished!




Next we applied 4 coats of wax followed by 2 coats of PVA mold release. Tomorrow I'll cast the mold.






Here you can see how we built the clay up on top of the foam. Very simple and the results are fantastic for this type of curvy, hard to flange part.



Click here to go to part 2 of this project.
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therivermonster screwed with this post 01-21-2013 at 12:04 PM
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