Tube cutting question

[arthur dent]

What is the best way to cut tubing up to BT80 and are there any products available to do this????

 

[KermieD]

Look on Rocketry Online in the InfoCentral section. There's a great article there on a tube cutting jig. I believe there are a couple of very good threads here on the topic as well if you do a search.

 

[sandman]

Go here and click on the "Tube Cutting Jig".

https://www.info-central.org/index.cgi?construction

Works great with the addition of one other item...a really necessary one!

A Mandrel!

An interior tube (heavy) for the blade to cut against so it doesn't crush the tube.

For BT-5's use a spent 13mm motor

BT-20 use a spent 18mm case

Same with a 24mm (BT-50) and 29mm motor tube (if you can find a spent 29mm motor!)

For larger sizes they suggest a tube coupler but I like something beefier like a turned piece of oak or some other hardwood. It should fit snugly into the tube being cut.

It does take practice too!

sandman

 

[Stymye]

sandman
would you sell a mandrel set for a reasonable price..?.
just a set of correspondig I.D. dowells ..It's hard for us-non lathe owners to make a set and I (for one) would love to have a set!

 

[Rocketmaniac]

The method I use is with a hose clamp........ I measure and mark the tube in 2 or 3 places (around the tube)........ Then I install and tighten the hose clamp with the edge on the lines........ Then with a razor knife (hobby knife) I start making light and easy cuts around it, getting deeper each time around...........

 

[arthur dent]

Thanks guys..thats just what i need Thats the first time i've been to info central..wow it's got lots of stuff i need to read up on...cheers

 

[astrowolf67]

I wrap a piece of paper with a straight edge around the tube, and draw my cut line with that. Then, run a couple of layers of masking tape around at the cut line, and use an exacto knife with a fresh blade to make the cut. The tape gives the knife blade an edge to follow. If you do it this way, make several passes using light pressure on the knife. Don't try to cut through on the first pass. It'll usually take about 10 to 15 passes, but it leaves a nice straight cut.

 

[Vance in AK]

I really like Rocketmaniac's hoseclamp idea. I'll have to give it a try.
Vance in AK.

 

[Micromeister]

The Hose clamp works well. Try to make your cut with a new or sharpened #2 or 11 long narrow xacto blade and make the cutting motion outward toward the clamp band once you penetrate the tube wall.

Sandman is right for the cleanest, best cuts a mandrel is really the best way to go.

I build up whatever mailing tubes or huge dowels of about the right size with 2" masking tape until its a nice firm slip fit.

 

[Prowler901]

Now that's a great tip Micro. Thanks for sharing that one.

Regards,
Todd

 

[flying_silverad]

Originally posted by Micromister
The Hose clamp works well. Try to make your cut with a new or sharpened #2 or 11 long narrow xacto blade and make the cutting motion outward toward the clamp band once you penetrate the tube wall.

Sandman is right for the cleanest, best cuts a mandrel is really the best way to go.

I build up whatever mailing tubes or huge dowels of about the right size with 2" masking tape until its a nice firm slip fit.

John, is that an xacto blade I see in the photo on your jig? Do they cut better than a single edge razor?

JOHN R.

 

[Micromeister]

John:
Yes that is a #2 X-Acto blade in my cutting jig, which is sharp enough to shave
The second part of your question is a bit more complicated. in my case the direct answer in NO razor blades aren't sharper then xacto blades. Out of the package single edge razor blades are sharper than new Xacto blades but I never use any cutting tool with the factory edge.
My father taught me a saying years ago that he swore by for all cutting tools, knifes and chisels, " if it isn't sharp enought to shave with it isn't worth using". I almost never use a new tool or blade until it has been sharpened, Xacto blades are no exception. The factory edge on knifes and blades is never "good enough, Sharpening and stropping takes a few minutes but is well worth the time, extending the life of the blade by years. I have learned to strop my cutting tools every time I pick one up, so they are sharp enough to shave on every cut. Just a side note: "strop before use..every time you pick it up" is especially important with lathe turning chisels.
Besides single edge razor blades have the nasty triple thick back bar that gets in the way and makes clamping difficult
Heres another look at my cheapy home made cutting jig.

 

[sandman]

Micro,

I agree and dissagree! I've been honing and stroping cutting tools for years.

Especially carving tools, hand planes, and chisels. Yes, Exacto blades too!

Lathe tools are another matter...The "curled edge" left by grinding and honing is what makes the cut on lathe tools.

I have seen arguments both ways on lathe tools.

Oh, well, I guess it's a matter of what works for you.

We should leave that argument to the "Woodworking Forum".

sandman

 

[Rocketmaniac]

Originally posted by Micromister
Sharpening and stropping takes a few minutes but is well worth the time, extending the life of the blade by years.

Ok guys, what is stropping?

 

[sandman]

Rocketmaniac,

Do you ever remember seeing a western or a movie where someone goes into a barbershop for a shave?

The barber grabs this leather "strop" that's hanging from the barber chair and quickly rums the straight razor back and forth over it.

It kinda does the finishing polish on the blade edge.

The way you can tell if a blade is stropped properly is that you can see your reflection in it.

sandman

 

[Steward]

I thought stropping was like...well..you know...
Like stropping your car at the strop sign...LOL





ok i'll go to bed know...

 

[Micromeister]

Ah Ha Stewart! LOL That was funny.

I agree sandman, Whatever works best for the individual woodworker. All my lathe tools are hollow ground, hand sharpened and stropped before they ever touch a piece of wood. Then stropped each and every time I pick them up until a nick or chipped edge requires a resharpening

Maniac:
Sandman is correct. What he didn't tell you is the how.
That barbar strop, if you've ever seen one's in a shop..yes they still use them with straight razors, are by design very thick and very stiff. These straps are fairly wide more importantly they are treated with a buffing rouge that polishes the razor blade edge removing the "wire edge" created by sharpening and repolishes the edge to hair splitting sharpness between stone sharpenings.
A good way to check the sharpness of a blade is to stand it on
it back end and sight long the freshly stropped edge under a light or in sunlight, if you see any reflection from that edge it is not sharp. Stropping will also polish the sides of the blade to a high mirror finish.
One safety note! Never run you finger or thumb along a knife
edge to check it's sharpness. If you've done you job well all you accomplish is cutting you finger nice and deep.
If you don't have any 5-8oz leather scraps laying around your house.. an old or broken belt will do. I've found if I contact cement a small piece of leather to a scrap of wood about 1" wide
x 4" long it makes a wonderful tool strop. Be sure to cement the leather scarp with the smooth (Hair side) against the wood leaving the rought (flesh side) up to hold the rouge. Rouge can be picked up in a 1" x 2" cake of white stropping rouge from tandyleather.com for about a buck, That should last you a very long time.
Also remember stropping of any blade is done in the reverse direction as you would "sharpening". That is to say when sharpening a knife blade you try to cut a thin slice off the stone at about 30 degrees both sides, slicing away from your body. When stropping you draw the blade backwards, toward your body over the leather at that same 30 degrees, the more consistant your angle, the quicker the job will be completed, that may take a little practice.

For more info than you need... Most staright razors, razor blades and surgical instruments are sharpened with a 30/0 degree edge thats 30degrees on one side, flat or 0 degrees on the other. most general purpose knife, axe and double face chisels are sharpened 30/30 or 40/40 depending on the thickness of the blade.

Now to bring this thread back on subject, If you'll take a few minutes to strop your new, straight out of the pack, X-acto blades trying to match their factory edge angle as best you can, your blades will work as well as single edge razor blades.
Hope this helps

 

[Silverleaf]

<-has this image of Sandman with an ultra clean face, and even his dog and cat run for cover when its time to check the sharpness of the razor's edge.

Mexican hairless Chiahuahua would be a safe bet as the family pet ..No ?

All with tongue planted firmly in cheek 8)