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Cutting 7.5" Tube

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davdue

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I have a couple 7.5" PML airframes that I have fiberglassed that I need to cut. I have used a hacksaw before but that is very hard to get a square straight cut on this big of tube. I have thought about using my table saw and cutting one side and the the other side. Any other ideas or suggestions?
 
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RocketFeller

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I use a piece of 2" wide tape to mark the cut. You can then cut it with a skill saw or by turning it on the table saw. A large sanding block can be used to finish it smooth afterwards.
 

JohnCoker

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I have used a table saw for this purpose, although since you've already fiberglassed the tube you will dull your blade fast.

You can either use a high fence on a sliding table or use a stationary fence perpendicular to the blade and "drop and roll" the tube with the end away from the blade riding against a stop. (Don't use the table saw fence on the other side of the blade because that might cause the cut-off part to kick back.)
 

MikeyDSlagle

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You can use hose clamps as a guide for your hacksaw or even for a dremel. Or chop saw oughta do the trick.
 

Handeman

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I made me a jig for cutting tubes on my table saw. It works to cut tubes square and also was used to trim the switch band on my av-bay after I glassed the band that was already installed. it's versital, but you have to build it right.

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The 90 deg pieces that the tube sits in is easy. mounting it to the flat board, takes a little more, BUT the real key is to make sure the oak (or other hardwood) piece attached to the bottom of the jig that fits in the guide in the table saw is snug and mounted so the tube will be square to the saw. The higher you put your blade, the more critical this becomes.

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I actually trimmed the end of the jig after the guide was attached.

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I cut a piece of 1/4" scrap plywood to the width of the tube. Since the faces are 1/4" wide and square, it has to widen the tube in that direction to fit in. This helps the piece stay in place and I use tape on the inside of the tube to keep it in place. A round head screw in the center of the end makes a single pivot point against the fence so any non-square ends of the tube won't affect how it is rotated. I make sure the piece is longer then where the tube is being cut. That way it stays in the part of the tube in the jig, but also keeps the cut off piece from rolling or flying off.

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Here I was just trimming the end of the tube to square it up.

This jig works best when just trimming ends, but if you do a rough cut with a hacksaw, it will square up the end very nice.

I've used this on tubes from 2" to 6" to square ends which I believe is critical for high G HPR when you have booster tube pushing on a switch band and the band against a payload tube.
 

KenRico

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I keep a roll of masking paper near my building bench.

I would wrap the tube with the paper to make a nice straight tubular line..then back it off the width of some masking tape and lay the tape up against the paper.

When the paper is removed you have a nice taped line., then break out the dremel with the harbor freight diamond cutting disk. . I kinda peck around and try to score a line ..then when happy let the blade drop through.. then it cuts pretty easy and the slot cut helps keep the blade on track.

This isnt as quick or the perfect cut. . But it is pretty managable..allowing time to check your work , rotate the tube or take a break.

Kenny
 

mccordmw

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I have a couple 7.5" PML airframes that I have fiberglassed that I need to cut. I have used a hacksaw before but that is very hard to get a square straight cut on this big of tube. I have though about using my table saw and cutting one side and the the other side. Any other ideas or suggestions?
I get straight cuts all the time using a hacksaw ever since I started using the technique I linked here. No followup sanding required.

http://www.rocketryforum.com/showth...3-4-Scale-PAC-3-Patriot&p=1670257#post1670257
 

warnerr

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I use John Cokers method on large tubes. The jig is even better but i find that i get lazy. I get perfect cuts in that i use a diamond blade in my table saw. For smaller tubes i prefer a tile saw. Either way the diamond blade is the only way to go.
 

davdue

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mccordmw

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By the time I'm down to the final cut, there's so little remaining material, that I simply run a utility knife around to finish it in one pass.
 
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