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tfulwider

Practice Kit - glassing the small wing section

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I'm going to ask what is probably a simple question to any of the builders out there but I'm stumped.  I have my wing section hot wired and prepped for glassing, but there's one area that concerns me.  I know you're supposed to scissor trim the glass that overhangs after you've wet it out and then knife trim flush to the foam part way through the cure.  I also know that you're supposed to put duct tape halfway down the leading edge so you don't get slurry or epoxy on the top portion to be covered later.  What I don't understand is how you trim up that leading edge.  I'm assuming you knife trim part way through the cure so the weight of the hanging fiberglass holds the layup in place.  But when you knife trim, how do you keep from cutting into the foam core?  

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Posted (edited)

Let the layup overhang get partly cured but still flexible.  It can be easily cut with a sharp box-cutter or razor knife.   It won’t hurt to cut into the foam a bit—no way to avoid it.   After it hardens, smooth the rough edge with a sanding block.

Edited by Kent Ashton

-Kent
Cozy IV N13AM-750 hrs, Long-EZ-85 hrs and sold

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Ok, that makes sense. I was worried that nicking the foam core at the leading edge would be a big no no. Thanks Kent!

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On 8/1/2020 at 5:55 PM, tfulwider said:

...and then knife trim flush to the foam part way through the cure.

That works, but requires you to be there at the right time; halfway before it cures.

On 8/1/2020 at 5:55 PM, tfulwider said:

But when you knife trim, how do you keep from cutting into the foam core?

Consider using an oscillating tool, either the best from Fein or a patent copy from Harbor Freight. Several other popular brands now offer theirs at Home Depot. Be sure to get the round high speed steel cutter (the straight cutters most often shown in ads require some skill, but can be used once you get a feel for the tool). You don't need a variable speed model in my opinion. I find you have all the control you need to be as precise as required using just hand pressure. 

I've shown this tool to Lancair and other prior builders and they've all remarked that they could have built their planes in half the time. I know that's an exaggeration, but it's one of the most valued tools I have for building.

fein.png


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Building a Cozy Mark IV

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35 minutes ago, Jon Matcho said:

 

Consider using an oscillating tool, either the best from Fein or a patent copy from Harbor Freight. Several other popular brands now offer theirs at Home Depot. Be sure to get the round high speed steel cutter (the straight cutters most often shown in ads require some skill, but can be used once you get a feel for the tool). You don't need a variable speed model in my opinion. I find you have all the control you need to be as precise as required using just hand pressure. 

 

fein.png

Are any of the round blades better than the others?  I saw a few choices for round there.  I'm guessing the HSS flush trim will be good?


Tim W.

Selling RV-8 empanage kit.  Gearing up for Open EZ build.  The struggle is real.

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19 minutes ago, TDubs74 said:

I'm guessing the HSS flush trim will be good?

I find the circular bits are most forgiving and capable for what needs to be done. That's the rightmost bit above, either half-round or full-round. I hardly ever use the 3 to the left, but have on occasion (the leftmost straight bit is actually a knife, which I've never used for building).


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Building a Cozy Mark IV

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I'm not sure I answered your actual question. Yes, high-speed steel (HSS) bits are recommended. The basic steel bits tend do lose teeth faster.

I have no issues buying bits at Harbor Freight (or wherever). Fein is an expensive brand.


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Building a Cozy Mark IV

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7 minutes ago, Jon Matcho said:

I'm not sure I answered your actual question. Yes, high-speed steel (HSS) bits are recommended. The basic steel bits tend do lose teeth faster.

I have no issues buying bits at Harbor Freight (or wherever). Fein is an expensive brand.

Thanks Jon.  I'm clear now.


Tim W.

Selling RV-8 empanage kit.  Gearing up for Open EZ build.  The struggle is real.

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Can’t imagine building without this tool!

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FZ

Long eze ,  Bottom of Chapter 9

Cozy Mark 4 # 1777  Chapter 5

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I happened to have gotten my hands on a Fein tool just a few weeks ago. It seems that would have more ability to damage the foam underneath than a razor blade would. I'll try it out and see how it does!

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You actually have more control with the vibratory tool then the razor blade. Since it does all the work very little pressure is required. You can use your other hand as a guide to control the depth. As an added bonus, no possibility of slicing the dickens out of yourself.

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FZ

Long eze ,  Bottom of Chapter 9

Cozy Mark 4 # 1777  Chapter 5

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I laid up the underside of the wing last night to cure overnight.  First off, the West 105 resin with the 206 hardener that ships with the practice kit cures really quickly.  My slurry was tacky before I even finished covering the foam.  The epoxy thickened quickly which made wetting out the glass a little more difficult than I had hoped.  I was in a 75 degree room and used a hair dryer at various points to help it flow.  The layups aren't as nice as I would like and I ended up with a few trapped bubbles of epoxy under the final layer.  Oh well, that's why it's practice!

Today I pulled out the Fein saw with the rotary blade and trimmed the edges.  Worked really well!!  I was able to lay the flat part of the blade on the edge of foam and get a very close cut.  The leading edge trim was a bit tougher and I ended up having to sand it a fair amount.  All in all, very pleased with how it went!  I noticed in Ary Glantz's videos that he would sometimes use a router with a flush trim bit on the edges.  Any advantages or disadvantages with that method?  

Thanks for all of the advice!!

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Interesting on the West 105/206. Recall from another discussion that it's not an approved combination -- only the 105 w/209 super slow hardener is approved (for workable pot life). You'll have a better experience with MGS 285 (if you care to afford all the hazmat charges) as it's much easier to spread. Your 75 degree room would have been more than fine without a hair dryer.

46 minutes ago, tfulwider said:

I noticed in Ary Glantz's videos that he would sometimes use a router with a flush trim bit on the edges.  Any advantages or disadvantages with that method?

You can use whatever tools that make sense for you. Way back I thought to router a few sections for a straight edge, but found it too cumbersome and even dangerous (not to mention the glass was eating my bits). I now just use the Fein tool on a marked straight line, and then sand to "perfection" using the longest Permagrit sanding block for the area. https://www.permagrit.com/sanding-blocks/


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Building a Cozy Mark IV

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1 hour ago, tfulwider said:

I laid up the underside of the wing last night to cure overnight.  First off, the West 105 resin with the 206 hardener that ships with the practice kit cures really quickly.  My slurry was tacky before I even finished covering the foam.  The epoxy thickened quickly which made wetting out the glass a little more difficult than I had hoped.  I was in a 75 degree room and used a hair dryer at various points to help it flow.  The layups aren't as nice as I would like and I ended up with a few trapped bubbles of epoxy under the final layer.  Oh well, that's why it's practice!

How long did it take you to get your practice kit?  I ordered mine a week ago and it's still out of stock. 

I saw a Cozy Girrrl video saying to just dump the mixture out on the part as soon as it's mixed to slow down the reaction. I know the 206 is labeled a slow Gardner but still has a short pot life. Maybe you could try that next time. Anyway thanks for the heads up!


Tim W.

Selling RV-8 empanage kit.  Gearing up for Open EZ build.  The struggle is real.

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1 hour ago, Jon Matcho said:

Interesting on the West 105/206. Recall from another discussion that it's not an approved combination -- only the 105 w/209 super slow hardener is approved (for workable pot life).

ACS gives you the 105/206 with the practice kit. 


Tim W.

Selling RV-8 empanage kit.  Gearing up for Open EZ build.  The struggle is real.

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I've had my practice kit for a while and just now getting to the wing.  I was mixing single squirts and then dumping the majority out to work it.  Took a while to cure completely, but was setting up to a gel consistency within 5-10 minutes.

 

Jon,  thanks for the info on the Permagrit.  Definitely going to have to pick them up!

 

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9 minutes ago, tfulwider said:

Jon,  thanks for the info on the Permagrit.  Definitely going to have to pick them up!

You're welcome. Hint: Do NOT use them on anything but fully cured epoxy otherwise you'll transform your 80-grit tool into a 300-grit tool. Ask me how I know. 🙂 They do sell replacement paper which is metal-backed and very long lasting. Their rotary bits are quite useful as well.


Jon Matcho :busy:
Canard Zone Member & Administrator
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Building a Cozy Mark IV

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