Cutting Seatback bulkhead

[rnbraud]

Justa curious newbie, but are the seatback bulkhead cutouts called out for after the first layup. Wouldn't be easier to cut the raw foam first then do the layups? This way we would only have to knife trim all cutouts, with the dritz, and sand when cured.

 

Also, when should we remove the peel ply, after compete cure or after we knife trim?

 

Thanks.

[argoldman]

Justa curious newbie, but are the seatback bulkhead cutouts called out for after the first layup. Wouldn't be easier to cut the raw foam first then do the layups? This way we would only have to knife trim all cutouts, with the dritz, and sand when cured.

 

Also, when should we remove the peel ply, after compete cure or after we knife trim?

 

Thanks.

Do not remove the peel ply until just before you are going to use the part. The peelply is somewhat of a protector from dust, and stuff that is floating around your shop, and resists contamination by hand oils, grease etc. Plus there is no reason to remove it until needed.

 

When you are going to remove it, after removal sand the areas to be bonded lightly with 36 grit sandpaper (very easy because of the peel ply) and bond.

 

There is some controversy as to whether the sanding is even necessary.

[CFernandez]

Justa curious newbie, but are the seatback bulkhead cutouts called out for after the first layup. Wouldn't be easier to cut the raw foam first then do the layups? This way we would only have to knife trim all cutouts, with the dritz, and sand when cured.

 

Also, when should we remove the peel ply, after compete cure or after we knife trim?

 

Thanks.

Cutting thru the glass and foam is not a big deal. I used a small hacksaw.

 

I would take the peel ply off after cure (24 hours). Waiting longer (days? months?)you might forget it is there. Installing the part somewhere with peel ply on is not acceptable. Take it off sooner than later.

 

Sanding before installing a peel plyed part ensures you get the areas that the peel ply wasn't able to get to (usually a small area).

[rnbraud]

Even though cutting through cured fiberglass isn't too difficult, it would seem so much easier to have the basic shape their in the foam and then the knife trim would be a "piece of pie!". Also, knife trimming removes any chance of delam and so forth. Finally, the other bulkheads are indeed "pre-cut" so it would seem the seatback could be also.

[Jerry Schneider]

Even though cutting through cured fiberglass isn't too difficult, it would seem so much easier to have the basic shape their in the foam and then the knife trim would be a "piece of pie!". Also, knife trimming removes any chance of delam and so forth.

If you have the Fein Detail Sander (w/blade), you'll never wait for the "knife trim stage" again. Plus, the cutouts are at an angle thru the seatback due to the angle it is mounted in the fuselage. This is easily done with the Fein.

In an earlier post, the Dritz were mentioned as what's used to knife-trim. The Dritz will only cut wet or dry glass... not cured. And you'll still end up with sharp edges, no mater how close you trim the wet glass with the Dritz.

Finally, the other bulkheads are indeed "pre-cut" so it would seem the seatback could be also.

True, they are pre-cut, but you'll find, after they are glassed, you'll be knife trimming (chewing gum stage) or, better yet, trimming after cure with the Fein anyways.

 

If you're serious about building a plane, get the Fein. It saves mega-time, and enables you to produce quality work with minimal effort.

 

"Wherever 2 people are gathered in the name of an easier way... there so am I."

[rnbraud]

I have already purchased the Fein, the Dritz, and a rotary cutter. I have practiced with the rotary cutter, but not yet the Fein or the Dritz. Busy building the table and the fabric cabinet.

 

I think I need to just cut up my practice pieces with my brand new Fein and get the hang of it.

 

Thanks for all the info. Hopefully, if AS&S "EAST!" comes through with my first materials delivery I will be building, and cutting, real stuff real soon.

 

Later.

[Jon Matcho]

Even though cutting through cured fiberglass isn't too difficult, it would seem so much easier to have the basic shape their in the foam and then the knife trim would be a "piece of pie!". Also, knife trimming removes any chance of delam and so forth. Finally, the other bulkheads are indeed "pre-cut" so it would seem the seatback could be also.

I agree w/Jerry. An issue with having too many turns and corners is that the glass will want to move around a little bit. I found it easier to keep things flat, and cut later. Cutting with the Fein on this is easy.

 

I'm sure you could get away either way.

 

On the peel ply -- whatever you do, do NOT remove it while the glass is anything but fully cured. Once it's fully cured, shear-rip (pull flat in the direction you're ripping) it off to create the roughed-up surface.

 

Don't worry too much -- this section is designed for you to make mistakes.

[argoldman]

I agree w/Jerry. An issue with having too many turns and corners is that the glass will want to move around a little bit. I found it easier to keep things flat, and cut later. Cutting with the Fein on this is easy.

 

I'm sure you could get away either way.

 

On the peel ply -- whatever you do, do NOT remove it while the glass is anything but fully cured. Once it's fully cured, shear-rip (pull flat in the direction you're ripping) it off to create the roughed-up surface.

 

Don't worry too much -- this section is designed for you to make mistakes.

 

If your are concerned with leaving the peel ply on by accident, After cure cross hatch it with a felt tip pen.