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Kites! Kites! Kites! => Kite Building and Repair => Topic started by: PUZZLE on May 28, 2012, 06:14 AM



Title: Best way to cut carbon spars
Post by: PUZZLE on May 28, 2012, 06:14 AM
Broke a le carbon spar and need to cut the new one to size . Do you score it with a knife use a drumel?


Title: Re: Best way to cut carbon spars
Post by: sugarbaker on May 28, 2012, 06:41 AM
dremel cut-off works great.
When using a dremel tool, I first tape the spar where I want to cut it... tape on the portion I'll be keeping. Then cut with a large fiber cutoff disc. I cut 1 mm longer than intended so that I can sand/file the end of the spar to exact dimension and taper the edge of the spar slightly to prevent it catching on the leading edge dacron. 


Title: Re: Re: Best way to cut carbon spars
Post by: DD on May 28, 2012, 07:02 AM
I have used dremel or a fine tooth hack saw, rotating as I cut, but still using tape


Title: Re: Best way to cut carbon spars
Post by: Will Sturdy on May 28, 2012, 07:07 AM
I use a cutoff wheel in an arrowshaft cutting jig. That keeps lengths precise and cuts square.

Don't cut all the way through the wall at any point at first - start the cut all the way around before going through. This reduces splintering. Tape also helps.

Hacksaws are the most controllable method. I would only recommend using a dremel or any other cut off wheel not in a jig if you are 100% comfortable with it and have a very steady hand. Personally I can't get a square cut using one freehand.

Will


Title: Re: Best way to cut carbon spars
Post by: tcope on May 28, 2012, 07:10 AM
Chainsaw... the more cc's, the better.

Be a man!

Oh... and tape of course.



Title: Re: Best way to cut carbon spars
Post by: PUZZLE on May 28, 2012, 10:05 AM
let family fly my innerspace and lawn dart broken le, My favorite kite!


Title: Re: Best way to cut carbon spars
Post by: Smeagol on May 28, 2012, 12:00 PM
I use an arrow saw, but I'm a rod cuttin' fool.  ;)  The Weston 8000 rpm arrow saw has been known to drop down to $99 on Amazon, pretty good for what you get.

dremel or cheap harbor freight chop saw works if you're only cutting a few rods.

-Mike


Title: Re: Best way to cut carbon spars
Post by: Ara Ararauna on May 28, 2012, 12:20 PM
Chainsaw... the more cc's, the better.

Be a man!

Oh... and tape of course.

Hugh?   ???   ???


Title: Re: Best way to cut carbon spars
Post by: tcope on May 28, 2012, 12:35 PM
If using the chainsaw you don't just cut right through it... that would be stupid. You score the edges first. Let's not get crazy. It also helps to have a (good) friend hold either side of the rod while cutting through it. Proper eye protection is a must.


Title: Re: Best way to cut carbon spars
Post by: Allen Carter on May 28, 2012, 12:42 PM
A hand held rotary too can cause more trouble that it's worth. They really send carbon dust flying, which is not good. If I had a vise, I'd lock it down and bring the part to the wheel. I use it when I'm in a hurry and have a cut list for a whole frame.

Most of the time I use a 32tpi hacksaw blade hand held, followed up with a fine file.

Holding the blade in your hand gives you the touch to go through even delicate rods with no problems.

Tape just seems to gum things up and slow you down. What's the point? Maybe with too coarse and/or slow blade on a hand held power tool it keeps it from skittering along the rod when starting a cut?

If I had a workshop I'd have a chop saw like Mike. I used to borrow the one at GWTW back in the day.


Title: Re: Best way to cut carbon spars
Post by: WorldWind on May 28, 2012, 02:01 PM
Tape, measure, mark, re-measure, protective goggles, while rotating spar by hand; cut with high-speed cutoff wheel, sand flat and bevel with 220 wet sanding block.
(http://i676.photobucket.com/albums/vv124/WorldWideWind/WWWJamsessionSpreaders.jpg)


Title: Re: Best way to cut carbon spars
Post by: tcope on May 28, 2012, 02:38 PM
With a chainsaw there is almost no dust. Sure, a few pieces might go flying... but no dust.


Title: Re: Best way to cut carbon spars
Post by: madhabitz on May 28, 2012, 02:56 PM
Like Allen, I think Mike's cutoff saw looks awesome (watched a YouTube video). Way cool.

I've only cut one spar so far (heh), so take my ideas for what they're worth. I'm mainly posting because it just can't hurt to gather more ideas, right? Never know when one idea will inspire another. In any case I'm into making jewelry, so I had a few tools on hand that worked for me:

Sawing Jig
Used to hold wire or tubing in place while sawing. Perfect for when you need to make many cuts all the same size. Only drawback is the length of wire/tubing you can cut with this jig unless you remove the rod/stop-thingy.
(http://www.contenti.com/products/saws/400-135LARGE.jpg)

If you need a longer length cut, a piece of wood (2x4 would work) with a v-shaped groove cut down the length of it will hold tubing, with your fingers holding the tubing down. You'd do your sawing at the edge of the wood.

Sawframes
A jeweler's saw is awesome... and not just for jewelry. I've used mine for a ton of different projects (cuts metal or wood... and spars!) and it's been worth every penny I paid for it. An expensive sawframe would be great, but I've found that my cheapie works just fine for my needs. I think I paid under ten dollars for it. Lots of video on how to use can be found online (there is a bit of technique to sawing).
(http://www.contenti.com/products/saws/400-342LARGE.jpg)

Sawblades
The teeth on a jeweler's sawblade are very very fine-- the more teeth per inch, the fewer burrs and/or splintering. There are sawblades and there are sawblades. I became a believer in the really good blades after spending hours trying to saw some things as a newbie. I sucked it up and paid more money for a few really good ones and oh man, what a huge difference. The good ones will saw through a coin like butter.

The Good Ones aren't all that expensive-- you can get a dozen of one size for about four to six bucks from OttoFrei (http://www.ottofrei.com/store/Otto-Frei-Swiss-Jewelers-Saw-Blades/ (http://www.ottofrei.com/store/Otto-Frei-Swiss-Jewelers-Saw-Blades/)) or Contenti (http://www.contenti.com/products/saws/400-201-8_0.html (http://www.contenti.com/products/saws/400-201-8_0.html)). There are many places to buy blades, but these are the two places I would trust the most.

Sawblade Sizes
For what it's worth, I generally use a size 3/0 blade which is about average and it makes a darned smooth cut at a decent cutting pace. Here's a link to a sizing chart:
http://www.contenti.com/resources/library/sawblades.pdf (http://www.contenti.com/resources/library/sawblades.pdf)


(mods: I put the links in because I didn't think they were kiteshop competitors. I will understand if you need to take them out)


Title: Re: Best way to cut carbon spars
Post by: PUZZLE on May 28, 2012, 10:23 PM
tcope can i come use your chain saw? we can practice on some of your spars?


Title: Re: Best way to cut carbon spars
Post by: mikenchico on May 29, 2012, 12:17 AM
Tape, measure, mark, re-measure, protective goggles, while rotating spar by hand; cut with high-speed cutoff wheel, sand flat and bevel with 220 wet sanding block.

What Worldwind says, I lay the spar on a table and roll it into my Dremel, not as fancy as Steve's spar cutter but basically the same idea. I've never split a thinwall spar using this method. Handholding on the thicker wall pultruded spars can be more difficult with the possibility to bind on the blade, I tend to cut those a bit long and sand down to size. I always smooth the cut with some fine sandpaper too.


Someday I'll buy a build a dedicated spar cutter.



Title: Re: Best way to cut carbon spars
Post by: WorldWind on May 29, 2012, 12:20 AM
It's all about confident when familiar.
And it is not rocket science after all.
A smooth clean cut with no cracks or splintering is way more important than achieving precession better than plus or minus half a mm.


Title: Re: Best way to cut carbon spars
Post by: madhabitz on May 29, 2012, 12:49 AM
...I lay the spar on a table and roll it into my Dremel,


I'd say that's the ticket with the Dremel/cutoff wheel combo. Seems like it would be easy enough to build a stand to hold the Dremel just right, leaving your hands free to do the deed.


Title: Re: Best way to cut carbon spars
Post by: Smeagol on May 29, 2012, 12:55 AM
I agree on the carbon dust, gets kind of annoying if you're cutting multiple rods.  I tend to sometimes hold up the shop vac near the cut when I want to keep things clean and not get dust everywhere.  They do make the same saw with a shop vac attachment, but it was nearly $50 more for a little extra piece of plastic.  I'm going to just make up my own to hold the vac hose in place. ;)

-Mike

A hand held rotary too can cause more trouble that it's worth. They really send carbon dust flying, which is not good. If I had a vise, I'd lock it down and bring the part to the wheel. I use it when I'm in a hurry and have a cut list for a whole frame.



Title: Re: Best way to cut carbon spars
Post by: inewham on May 29, 2012, 01:25 AM
Just be careful with the dust - while carbon fibres aren't particularly dangerous themselves they are exceptionally good at carrying other dirt into your body with them. Wear a mask, goggles, cut through the tape or cut wet.

Once upon a time people used to think Asbestos was harmless.



Title: Re: Best way to cut carbon spars
Post by: ozzymat on May 29, 2012, 04:56 AM
Junior hack saw and a mitre box works for me.

Here's my home made mitre box that accepts Skyshark, 6mm and 3mm the 3mm has a stop just to get the accuracy up for the stand off's.

For the cleanest cuts
- Use a 32 TPI junior hacksaw blade.
- Put a layer of masking tape on the section before cutting.
- Only cut half way through before rotate the rod 90 deg, cut some more then a final turn to finish the cut.
     the idea is to only cut the tube from the outside to the inside to prevent tearing.
- Finally smooth the edges with a bit of 320 wet and dry or sandpaper.


(http://img801.imageshack.us/img801/3750/mitrebox1.jpg)

(http://img411.imageshack.us/img411/5430/mitrebox2c.jpg)

Mat


Title: Re: Best way to cut carbon spars
Post by: thief on May 29, 2012, 06:08 AM
I have been using a dremel for 15 years now....only way for me....i do not use tape to mark the spot - i will mark the rod with a sharpie if it is light...and most of the rest of the time i grab the rod and have my thumbnail at the cut spot and cut just past it..trimmable if needed...

hacksaw: i have one in my kit...and hate using it....i find it much less controllable and fight the darn thing....rather put the broken kite away until i get back to my workshop...


Title: Re: Best way to cut carbon spars
Post by: PUZZLE on May 29, 2012, 08:49 AM
Thanks for all the good information :)


Title: Re: Best way to cut carbon spars
Post by: Doug S on May 29, 2012, 02:46 PM
A dremel with a cutoff wheel works the best.  I mount my dremel in a dremel drill press, which can be rotated 90 degrees into a horizontal position.  For prior production work, I used the power takeoff on my dremel jig saw with a cutoff well, which I mounted in a small box plywood that I clamped to my work table.  The plywood box provided me with a flat surface to control/rotate the graphite spar when cutting.  You want to have both hands free to hold/control the carbon spar.  Also, have a vacuum or fan running, since you don't want to breathe in the carbon dust.

Use blue masking tape to mark the desired location on the carbon spar, placing the tape on the side you are going to keep/use.  Remember that old carpenter phrase "measure twice, cut once."  When cutting, rotate the spar in your hands so the cut proceeds even through the spar.  Carefully clean up and radius the cut end with fine sand paper.  I seal the ends with a small amount of fast drying crazy glue.


Title: Re: Best way to cut carbon spars
Post by: ae on May 31, 2012, 12:01 AM
Call me nuts, but I'm using a arrow saw to cut my spars :)


Title: Re: Best way to cut carbon spars
Post by: mikenchico on May 31, 2012, 07:30 AM
... and let the saw do the cutting, rotating every few strokes ...

In case anybody missed it above ..." LET THE SAW DO THE CUTTING" ... best advise in the whole thread. If you force it you will split an expensive spar.

No need  to ask how I know this   :-[ 





Title: Re: Best way to cut carbon spars
Post by: thief on May 31, 2012, 08:30 AM
... and let the saw do the cutting, rotating every few strokes ...
In case anybody missed it above ..." LET THE SAW DO THE CUTTING" ... best advise in the whole thread. If you force it you will split an expensive spar.
No need  to ask how I know this   :-[ 

Totally agree!

Now...what did you do!?!?!?!?


Title: Re: Best way to cut carbon spars
Post by: Rliquidice on May 31, 2012, 08:49 AM
Chainsaw... the more cc's, the better.

Be a man!

Oh... and tape of course.


  This got the first grin of the day for me !    ;D


Title: Re: Best way to cut carbon spars
Post by: madhabitz on May 31, 2012, 10:07 AM
and let the saw do the cutting

+1

Same with the jeweler's saw....which is just a hacksaw with really really fine teeth


Title: Re: Best way to cut carbon spars
Post by: Tmadz on May 31, 2012, 10:25 AM
Chainsaw... the more cc's, the better.

Be a man!

Oh... and tape of course.


  This got the first grin of the day for me !    ;D

Is this the only time we'll be able to write "Husqvarna" on this forum?


Title: Re: Best way to cut carbon spars
Post by: Dolphinboy on May 31, 2012, 10:36 AM
I've used a Dremel with a mini cutoff wheel but it's kind over over kill and I just end up using a fine tooth hack saw most of the time. Like others have said, let the saw do the cutting, don't force it and use masking tape to wrap the rod before cutting.


Title: Re: Best way to cut carbon spars
Post by: Rx8doc on May 31, 2012, 10:36 AM
http://www.amazon.com/dp/B000VWHTUG/?tag=carolpa-20 (http://www.amazon.com/dp/B000VWHTUG/?tag=carolpa-20) was thinking about buying this. Thoughts please


Title: Re: Best way to cut carbon spars
Post by: Dolphinboy on May 31, 2012, 10:44 AM
[url]http://www.amazon.com/dp/B000VWHTUG/?tag=carolpa-20[/url] ([url]http://www.amazon.com/dp/B000VWHTUG/?tag=carolpa-20[/url]) was thinking about buying this. Thoughts please


If you used the mini cutoff wheels with it, it should work. But still go slowly and I'd still wrap the rod with tape 1st.


Title: Re: Best way to cut carbon spars
Post by: thief on May 31, 2012, 11:04 AM
there was a discussion about these (the harbor freight version which i think was even less$) and using a reinforced wheel that is offered as well.   overall response was good experience with them.

same thing though: rotate the rod while cutting it.


Title: Re: Best way to cut carbon spars
Post by: Smeagol on May 31, 2012, 11:15 AM
I almost bought that cutoff saw @ harbor freight but they didn't have any cutoff wheels in 2" at the time, just the metal blade which I didn't really want to use for cutting carbon.  I'm sure it would work though if you go slowly enough as has been mentioned.


Title: Re: Best way to cut carbon spars
Post by: Gamelord on May 31, 2012, 11:53 AM
I have been using a cordless Dremel with a diamond cut off blade for the last 3 years, it is lightweight, easy to get the exact angle and zips through carbon rods like butter.  The metal diamond blade on it never wears out...at least not in the last 3 years and I cut tons of carbon at the shop here.  No tape needed (but it does make it easy to see the cut line).  After cutting, I set the Dremel on end and round the ends of the spar on the blade.  Use a mask to protect from the dust.  It has never snagged or ripped/splintered the carbon, even when cutting P90's, Zero's or 4 wrap Rev rods, it just melts right through.

I would highly recommend this setup to anyone who is cutting large amounts of spars.  It can also be taken to the flying field with you if you ever wanted to be on the field doing spar repairs (personally, I don't bother at the park and in the event of a broken spar, just use another kite - this way I can maximize my limited flying time).


Title: Re: Best way to cut carbon spars
Post by: mikenchico on May 31, 2012, 12:44 PM
[url]http://www.amazon.com/dp/B000VWHTUG/?tag=carolpa-20[/url] ([url]http://www.amazon.com/dp/B000VWHTUG/?tag=carolpa-20[/url]) was thinking about buying this. Thoughts please


Been used by many, in fact kiteguy (http://www.gwtwforum.com/index.php?action=profile;u=748) here on our forum but more active over on Kitebuilder forum under the same name wrote up his mods to the Harbor Freight (http://www.harborfreight.com/bench-top-cut-off-saw-42307.html) version which is the same saw ($27.99). He removed that clamp system and installed a length of extruded aluminum L angle (http://www.homedepot.com/h_d1/N-5yc1v/R-202183479/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=aliminum+angle&storeId=10051#customer_reviews) I think he even glued a dressmakers fabric ruler (http://www.joann.com/dritz-fiberglass-tape-measure-120-/prd2809/) on it. Then you could add one of the window locks (http://www.homedepot.com/h_d1/N-5yc1v/R-100212527/h_d2/ProductDisplay?catalogId=10053&langId=-1&keyword=window+lock&storeId=10051) for sliding windows to give you a stop if you are cutting multiple spars the same length. Harbor Freight doesn't have 2" cut-off wheels to fit that saw but as I recall Dave (kiteguy) found that by removing the safety shield (Not recommended but hey my dremel doesn't have one) the 3" wheel (http://www.harborfreight.com/pack-of-5-3-inch-metal-cutting-discs-66393.html) they do carry will fit.



Title: Re: Best way to cut carbon spars
Post by: Rx8doc on May 31, 2012, 04:06 PM
that's why you guys are the best   :)
Thanks