Tow

[tenover]

Please define what "tow" is...When reading about glassing and a few other sailplane topics I often see "add fiberglass tow" or "Fill with carbon tow". I'm assuming it's just one of those two materials cut up into tiny little pieces? Thanks.

[davidfee]

Actually, TOW is just loose fibers in a bundle... like a non-woven rope. I'll attach a picture so you can see what I mean. The black one is carbon and the white one is glass. They come in different sizes and grades, of course. You normally buy a bunch of it on a roll.

have fun!
-David

[tenover]

Ahaa!! Thanks...So if I take a piece of 4oz. fiberglass and "un-weave" it, it wouldn't be the same because there's really no strength...correct? Thanks for the pics!

[Tony Oliver]

Not quite! - the important thing to remember with materials is what you want it for. Woven cloth when soaked with, say, epoxy is strong across and along the weave. There are situations - along wing spars for example - when the length is the only required strength. Any cross weave would be a waste of space and weight.
If you want an extreme example, try pulling glass tows (that word again) along the length in some way. You'll find it almost impossible to either snap or stretch it even before the addition of resin. However, if you try pushing it............. it's a bit bendy!

You can unpick cloth, but it's a messy and wasteful method.

There are different types of glass or carbon manufactured for specific purposes - what you described as cut up into tiny pieces - can be obtained as 'chopped strand matt' and has no direction , and is used for car repairs to fill and cover holes where strength isn't the main need. Others are available as tape of different width and weight - useful stuff for rigid joints in mouldings. There are different weaves to provide equal strength across and along the weave; some with max strength across, and some along the weave. There is also a rare type cut with a diagonal weave which is useful for joining wings - I've never had any but cut my own making diagonal tape - wasteful, but worth it as it gives more strength per unit weight for that purpose.

Get a copy of your nearest supplier's catalogue.

Be very cautious of these materials - epoxy, and polyester resins/hardeners/accelerators are dangerous if mishandled. The glass and carbon offcuts can get into your skin and lungs so take care to read up on the safety aspects.

Enjoy it

Tony

[tphillips]

I know what the term TOW means, but I've always been courious, is it an acronym or abbreviation for something :confused:

Terry

[steve lewin]

No, tow is just an ordinary English word which has been in use since the Middle Ages (for the textile equivalent not necessarily for carbon fibre ;)).

Steve

[Tony Oliver]

- didn't pick up your original meaning.

As Steve says, it's a normal English word found in most quality dictionaries - mine says "a coarse and broken fibre removed from flax, hemp or jute during scutching or hackling and used for twine etc (related to the Old Norse meaning uncleaned flax or wool)"

Well, we're all the better for knowing that!

Tony

ps Scutch - remove the woody fibres from flax
pps Hackle - a steel comb for combing flax or hemp

I hope you're all taking notes as there'll be a test on this later.

[Balin]

I've used carbon tow and I've used something called carbon tape which is well lined up and flattened tow with some adhesive so it MUCH easier to use.

How do others use the tow. Mine was a real mess by the time I was finished. Overlaps, thick areas and thin. Looked crummy even after covering. I ptu it on with CA and tried to spread it out and make it straight but didn't work too well. The tape I mentioned worked much better. Is it's only drawback it's price? Or is tow jammed in corners and separated into thin strands, etc that can't be done with tape.

Balin

[Bob K]

Tow is a term used for an UNTWISTED bundle of continious FILAMENTS. A YARN, on the other hand, is a bundle of twisted filaments ( and not necessarily continious).

Tow comes in various sizes. The individual filaments are USUALLY the same diameter within material groups. With carbon fiber tow, 3K, 6K, and 12K , are common designations. This refers ot the number of filaments in the tow. ( that's 3000, 6000, and 12,000 individual filaments PER tow )

Now, DENIER is the nomenclature for the filament size. If memory serves me ( Oh Nooooo ! ) Denier is calculated by weighing 1 kilometer of 1 strand of filament.

So a higher denier tow is a heavier tow, than a lower denier tow , filament count being equal.

Clear as mud?

Bob K

[Bob K]

memory was wrong. Denier is grams per 9 kilometers of one filament.