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panel lines on a cowl

Old 06-11-2003, 04:00 PM
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Default panel lines on a cowl

I have a 1:6 scale Beaver that I'm building and it has a good gel-coated fiberglas cowl, which is smooth and without detail.

The cowl is round and encloses a P&W radial engine. At the cowl midpoint thereis a fore-aft panel line where the upper and lower halves separate on the full-size plane, and there are also two rectangular latches on either side.

I think that I can cut or scribe the panel lines using an Exacto razor saw or a dremel with an emery cutoff wheel or a scrimshaw bit. I'm thinking it needs to be some .020" wide and .010-015" deep.

I've not done this before and some practice cuts on scrap 'glas suggest that it would work, but I thought I'd run it by the collective knowledge here...

--Bill
Old 06-11-2003, 04:10 PM
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Default panel lines on a cowl

Bill,
I just did this on Ziroli P-47 Cowl. I sanded the cowl with 400, then drew the lines with a pencil, then I used masking tape along the edge of the lines. I started with taping a metal straight edge along the line, then used a dremel cut off wheel (in your hand, not the dremel tool) and scribed the line. This worked ok, but broke a few cut off wheels. Then I started using a small jewelers file with a point and used that to get a good scribed line, then finished with the dremmel cut off wheel.
Old 06-11-2003, 04:36 PM
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Default Panel lines

Bill, Another method that does not involve cutting your cowl is to buy some 1/32 graphic tape from Chart Pak.. Put the tape over where a panel line is to be. Spray a few coats of primer over the tape and then lift the tape off. You will have a perfect resessed line.. Hope this helps BobH.
Old 06-11-2003, 04:48 PM
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Default panel lines on a cowl

Bill,
Go with the method BobH describes. It works very well and is easy to do. It also won't damage the integrity of the glass work, and if you aren't happy with the line it's just a matter of sanding the primer back down and repeating. No filling is required.
Tip: If you have some lines that go right around the radial cowl what I have found to work well is placing the cowl nose down on the bench and mount a sharpie pen in a holder of adjustable height....even a stack of books is fine...holding the pen still, spin the cowl around and you will get a nice straight line around your cowl to follow with your tape. In fact, I use this method for all my vertical panel lines the length of the fuse.
Old 06-11-2003, 05:28 PM
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Default panel lines on a cowl

I agree with BobH. Use drafting tape on the cowl with several coats of primer. A good 2 part automotive primer works best but is not required.

An alternative to this method, if very thin lines are required, is to squirt on the primer and sand to your desired finish. Then score the lines in the primer with an exacto knife.

I would never recommend scoring the fiberglass itself.

Chuck
Old 06-11-2003, 06:35 PM
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Default panel lines on a cowl

Do you need to run your knife along the edges of the tape before you pull it up?
Old 06-11-2003, 06:42 PM
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Default panel lines on a cowl

Dig it,

No, I haven't found that you do. But then I'm not leaving this tape on for days. just about 20-30mins then pulling it up. Leave it (the primer) to dry fully then wipe the whole thing down with some 400 grit paper and carry on. This will knock down any sharp edges that may be left from removing the tape.
Old 06-11-2003, 11:15 PM
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Default Yep

I've been using the tape/primer method suggested by SMchale for years, and it does work well, with a minimum of fuss.

Here's my high-tech tool, similar to the one described above.
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Old 06-11-2003, 11:19 PM
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Default Panel Lines

And here's a photo of the results...

The dark color is simply the primer below the paint showing through. (In this case, we used the final surface coat (PPG paint) to create the panel lines.)
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Old 06-12-2003, 01:57 PM
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Default panel lines on a cowl

Great info! I'll get some chart tape.

Got off my duff and did a search on panel lines and chart tape and came up with a lot of info on it.

Thanks!

--Bill
Old 06-12-2003, 02:34 PM
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Default panel lines on a cowl

Good luck! Gotta love RCU!!
Old 06-12-2003, 06:29 PM
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Default panel lines on a cowl

Bill, I use the primer / tape method also. You can see this done on my cowls if you go to my homepage, then on to the B-25 site and the detail page. It works well..
Old 06-13-2003, 04:44 AM
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Default panel lines on a cowl

Bill:

THe chart tape and primer method is the best way to get recessed panel lines. Here is a picture of the wing of a P-47 that uses this method.
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