JoneZ

best way to cut a Skyshark Spar

28 posts in this topic

I know using a dremmel would be the best way, but I just don't have one, and need to cut a new spar for my Widow.

Anyone have any suggestions?

All else fails Im just gonna grind the 5" off with some 80grit. hehe

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I ended up just grinding it down, but Im still interested in other ways asides from a Dremmel that would work. :)

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Some folks wrap the spar tightly with tape and then cut it with a very fine toothed hobby saw. Follow that up with some sandpaper on the cut end.

A table saw or a skill saw with an abrasive wheel would work. That would kind of scare me though. The small saws to cut ceramic tile seem like they would work.

I'd still give high consideration to buying an inexpensive rotary tool (Dremel). Harbor Freight has them for about $10. You'll find so many other uses for it that it'll soon wear out and you'll be forced to buy an expensive one, so that might not be a good idea after all. Seriously, I probably have about six rotary tools (Dremel, Black & Decker, no name) around the house with a large assortment of accessories that get used all the time.

Cheers,

Tom

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Arrow Saw

41h1sSmntvL._SS400_.jpg

Rx

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Arrow Saw

41h1sSmntvL._SS400_.jpg

Rx

RX,

The trouble with a $100 ~ $150 dedicated arrow shaft saw is that it uses up money resources and it's not useful for much else. I've cut about 70 carbon fiber rods in the last two months ... but, not a single one in the previous two years.

In my case I upgraded to what you see in the picture ... a flex shaft. In the past I've simply duct taped the Dremel to a two-by-four, clamped the end block at the set distance and cut the shaft. I had to provide a couple of spacers to raise the shaft up to be even with the axis of the cut-off wheel ... no big deal. My first Dremel was fat enough and the cut off wheel small enough that I first had to cut the shaft by hand about a half inch too long. Then it could be cut on my Redneck arrow shaft saw. The upgrade to a flex shaft allowed me to route a couple of groves in the two-by-four to lower the cut off wheel to the same level as the surface of the board. No more duct tape (redneck pewter) to hold the Dremel in place. And, the small profile of the bit end of the flex shaft and the large diameter of the new cut-off wheels alleviate any preparation ... simply cut away.

Cheers,

Tom

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Arrow Saw

41h1sSmntvL._SS400_.jpg

Rx

The business end of that saw is a mini chop saw from Harbor Freight. http://www.harborfreight.com/cpi/ctaf/disp...temnumber=42307

They work OK, except that the life of the metal blade is pretty short cutting when you cut carbon. They sell a 2" abrasive cutting disk that will fit, but they never seem to have them in stock.

The saw itself has very little torque, so cutting is pretty slow.

If you happen to have a compressor, Harbor Freight sells a micro die grinder http://www.harborfreight.com/cpi/ctaf/disp...temnumber=47869

Uses Dremel accesories - you just have to be careful not to over-rev them.

Combined with a diamond cut-off blade, it cuts like butter.

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Anyone have any suggestions?

Drive across the river........ :D

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Anyone have any suggestions?

Drive across the river........ :D

River?? You mean riverS! Let's see; there's the Illinois, then the Mississippi, the Missouri, the Yellowstone, the Snake and probably the Columbia. And those are just the big rivers!! No, the dremel is probably faster. Thanks anyway.

Cheers,

Tom

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I just whack them off with a hacksaw....works fine.

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Don't know if this has been tried.... but being a gearhead and not being able to find my hacksaw for my first rod cut( as recommended in some threads) . I grabbed the brake line cutter. The pressure you put on the rod needs top be payed attention to, but with a few spins around a couple of minor tightenings after each spin.... whalla! Nice STRAIGHT even cut.

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Go with a Dremel, with a fine, cut-off disc ! The higher the speed (rpm's), the better..........

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Yep, I use a cordless Dremel here - I also run a vacuum hose to my cut point as well, to suck up the carbon dust (yuck). ;)

Hack saw blades do in a pinch, especially when used with care, but I've had a few untimely bad cuts.

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Yep, I use a cordless Dremel here - I also run a vacuum hose to my cut point as well, to suck up the carbon dust (yuck). ;)

Hack saw blades do in a pinch, especially when used with care, but I've had a few untimely bad cuts.

Yes, I forgot to mention the shop vac. That dust is indeed nasty, and probably not too good for your lungs !

The problem with the hack saw, even the fine tooth hobby (X-acto) type of saws, is the gap between the teeth. If that gap between the teeth, exceeds the wall thickness of the tube, then the saw will grab, pinch, and/or splinter the workpiece, just about every time, even with tape. Should you mess up, and splinter your cut, the cure is then just a few drops of CA's (cyanoacrylates), such as "Zap (Pink Label) Thin Viscosity" glue. This super thin glue (the thinner, the better), which is often referred to as "hot", will penetrate into even the smallest (even invisible) splits and/or tears in the carbon or fiberglass tubing. Just run a few drops of this stuff (it's like water) around the inside and outside, of the end of the tubing, and once it dries (it will dry very quickly), you can then lightly touch up the end of the tubing with some very fine sandpaper, should there be any objectionable irregularities. CAUTION: this stuff will permanently glue your fingers, hands, feet, or whatever, to anything they touch. Use with extreme caution, especially if you don't have a bottle of de-bonder on hand.

Another cure for fraying and splintering (if you don't have CA glue), is to dip the very tip end (1/8" - 1/4" or more) of the tube, into a mixture of two part epoxy glue. Then hold that end of the tube down (over a piece of newspaper), and gently heat it with a heat gun, or hair dryer. This will cause the thick epoxy glue, to become very thin, allowing it to run, and drip off of the end of the tube (preferably onto the piece of newspaper), but it will also seal up any splinters or cracks, that may be in the tubing. Again, once cured, the tube can be touched up with fine sandpaper, if need be. The only drawback to this method, is the curing time, which is usually longer than the CA's, but once done, it definitely won't splinter on you any more. :ani_victory:

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Just checked on the Harbor Freight website and a dremmel-like tool with a number of cutoff wheels is selling for $8.99 with $6.99 flat rate shipping. Since there's a risk of damaging a $5~$11 rod (technically a tube if it's hollow) by "sawing" off the end, a $16 investment might be a good option.

Masking tape and a very, very fine blade hobby saw actually does a better job on small diameter fiberglass rods (not hollow) than the powered cutoff wheel.

Cheers,

Tom

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It would be very hard to find a suitable saw. The rule-of-thumb for saws is three-teeth-in-the-work - and that means three teeth in the near wall and three teeth in the far wall when you are about half way through the cut. Given the extreme thinness of tubular kite spars, I doubt you are going to find a saw (straight or circular cut-off) with enough teeth-per-inch to satisfy that criterium. Abrasive cut-off disk is the way to go. (With a vacuum!)

A saw that is nearly fine enough will suck you in, as there can easily be three teeth in the work as you start the cut, when the blade is nearly tangent to the surface of the spar. When you get a bit farther into the cut, it starts dragging fibers out and splintering.

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Ha! Didn't realize the thread was so old.

I agree with the Dremel or air saw. Cut off wheel was my first thought, but without a small vise or some type of jig to hold the rod and a high speed wheel..... I had visions of the rod bouncing and dancing like a Mexican jumping bean.... And breaking. Also didn't want my fingers that close to the cut to stabilize the rod. I saw the multiple setups that were pictured that others use. I was more in the "keep it simple stupid" state of mind.

The line cutter worked great ..no dust,no batteries or compressors,no noise and they make them small enough to fit in the palm of your hand.....perfect for your kite box or bag. Although I would have one dedicated to rods, as the cutting wheel tends to dull using it on metal lines over time.

All the "possible" mishaps with cutting via all methods can still be repaired in the same manner with the glue..if need be.... But with the same amount of care as using power tools... should be no issues.

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... I had visions of the rod bouncing and dancing like a Mexican jumping bean.... And breaking. ...

Hmmm, a 2 x4 and some duct tape (Redneck pewter) works well as a clamp.

Cheers,

Tom

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Well, duct tape and weed eater line have solved many issues for me.  must be a southern jeeper thing.

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Yep, yep, yep ! :ani_victory:

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Well, duct tape and weed eater line have solved many issues for me.  must be a southern jeeper thing.

Duct tape, bailing wire, weed eater line, nylon stockings, whatever it takes to get back on the trail or back in the air depending on if you are rough housing the jeep or pile driving the kite. Best hobbies there are!

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One other thing that can help. A block of hardwood with a hole that fits the spar very closely. Then cut through the wood and the spar at the same time. You might pull a few fibers on the inside of the spar, but the outside will be well-supported.

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On 12/10/2012 at 0:47 AM, --Pete said:

It would be very hard to find a suitable saw. The rule-of-thumb for saws is three-teeth-in-the-work - and that means three teeth in the near wall and three teeth in the far wall when you are about half way through the cut. Given the extreme thinness of tubular kite spars, I doubt you are going to find a saw

I used a fretsaw to cut pultruded carbon fibre spars (before I lost the blades somewhere). By fretsaw I don't mean scrollsaw, but the hand tool that looks like something like a coping saw. Today I use a coping saw for pultruded carbon fibre spars (works, but doesn't feel optimal because of the low teeth density), but so far I've never needed to cut a wrapped thin walled spar. 

Considering that you can find fretsaw blades 0.24mm (0.01") thick with 23.5 teeth per cm (59 teeth per inch), i.e. teeth distance of 0.43mm (0.017"), shouldn't it be possible to do without power tools here for many cases? To check the specifications yourself e.g. search for "PEGAS Metal Cutting Fretsaw Blade".
 

On 12/8/2012 at 10:08 AM, John Barresi said:

Yep, I use a cordless Dremel here - I also run a vacuum hose to my cut point as well, to suck up the carbon dust (yuck).

When hand sawing and sand papering carbon fibre I always do it wet - no dust! I'm on a old newspaper to collect the "carbon mud". On the taped spar where the saw blade is I put a big drop of water. When finished I clean the blade with a wet household paper. If sanding is required I used a couple of square cm (less than a square inch) of fine wet and dry sand paper and water of course. When finished I clean the spar as well. Then I let the sand paper remain in the newspaper which I make a roll of and dispose. OK, perhaps a bit thorough. B.t.w. any requirements on the vacuum cleaners filters?

Do anyone know if it is would work well with a cutting disk of a Dremmel like tool to put a drop of water and direct the expected water/carbon jet to a paper or something or would the drop disappear too soon?

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Never have used water on mine.Thin walled tube cuts pretty fast and easy, doesn't leave too much debris. I have used a hacksaw with 32 teeth/inch (fine), taped where I planned to cut, gently sanded after cutting. Fine enough blades will do the trick, you appear to have access to something finer. Tape keeps the end from splintering. Be careful when sanding not to be so forceful as to make the tube splinter. Just wear eye protection and don't breath in the fine particles, should be OK. Unless you are cutting volumes of spars, the vac is overkill.

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