Question about glassing tubes

Should I slot the airframe before I fiberglass the airframe, or after? Right now, I'm leaning towards slotting the tube first, and then laminating. I'm thinking it will be easier to cut through the fiberglass layer before it fully cures than it would be to cut through everything at once after it's cured. Does this seem reasonable, or am I missing something?

I have never attempted to cut entire slots through a previously-laminated cardboard tube. Please keep that in mind.

Your instincts are consistent with my laminating experience, which admittedly is a lot less than many others here. When the tube has been slotted prior to laminating, the slots provide a perfect cutting guide for your hobby or utility knife as you cut away the overlaying fiberglass. This job will be very easy if you cut the glass when the epoxy is in the green stage. The end result will be very, very clean.

Good luck with your project.

A disadvantage to slotting first is that epoxy wants to go through the slot and into the interior of the airframe unless something is done to restrict it. I have also found its easier to laminate then slot IMO.
Draw your slots on the tube and once the FG has partially cured to the leather stage cut the FG then after full cure the rest of the slot can be cut through the tube. With CF its probably easier to just laminate then cut since it doesn't cure clear.

I thought that epoxy going through the slots might be an issue. Drawing on the slots then cutting through the glass at the leather stage is something I hadn't thought of. Thanks for the idea. I'll give it a shot when it warms up.

Check out this video on John Coker's site, should give a visual to every step of the process, including how he deals with the slots.

https://www.jcrocket.com/tube-wrapping.shtml

I slot pre-glassing. I don't use enough, as in TOO MUCH, epoxy for it to run all over in the slots.
I do cover a couple of CRs with teflon tape, then stick them in the slotted section, so that it keeps it's round.
The first thing I do after cutting the glass from the slots is seal the edges with CA.
Then, when I use emery boards and needle files to size the slot to absolute perfection, I don't have to worry about separating anything.

Can't go wrong following any of John Cokers advice too. I usually modify his methods slightly to suit my smaller scale glassing needs.

The issue I see with pre-slotting is compressing the tube when vacuuming or doing a tight wrap. I feel much better cutting the slots after.

Handeman said:

The issue I see with pre-slotting is compressing the tube when vacuuming or doing a tight wrap. I feel much better cutting the slots after.

Click to expand...

That's a valid concern, but you can wrap teflon tape around a CR or two and stick them under the slots to maintain the shape if you do want to cut slots first.