Threading tubing

When I saw Lou Crane's tip on threading copper tubing, I had ask this.

I use 1/4 ID aluminum tubing, which I thread, to make wing tip and tail weight tubes. I cap them with 1/4-24 nylon cap screw bolts.

Problem: I waste quite a bit of tubing trying to hold the tubing
tight enough to thread it.

Any hints??

Thanks
Bill <><

Make a 1/4 collet by getting a piece of steel or aluminum say about 1" square or hex. put a hole thru the center for a sliding fit on the tubing you want to hold. Then cut two or three slots into the piece lengthwise like radials from the center hole.

slide the tube in--clamp the piece and it will grip the tubing.

Or go to a used machine tooling place and get a 1/4" collet and a collet holder to mount on the bench and do the same.

These are used all the time to hold small round or other shaped rod or tube. THe trick is lots of contact area and equal clamping pressure.

i got a simpler solution curt..think about it...u could just put somthing in the id that just fits so u cant crush it and tighten that in a vise for tapping aluminum with a 1/4-28 tap...oh and use a small amount of cutting oil on th tap...ur threads will turn out nicer and it will be easier to tap that way...it may take u a few trys to get this right..but ull see...its simple...jim

Curt,
Good point about the collett, but it doesn't solve the problem of how "soft" the aluminum tubing is. It is hard to thread that size with a 1/4 tap, but the next size larger is too big to accept the threads. Dilemna. (did I spell that right? LOL!!)
The tubing twists and crushes soooooo easily, especially the twisting part, just above where ever it is clamped. If I want a 2" piece I have to start with about 4". I cut a couple threads, back it out, and go again. With the socket head cap screws it makes a very nice weight "box". Fishing sinkers slide right in.
Bill <><

LAST EDITED ON Nov-17-04 AT 03:54 PM (CST)
 
Hey Bill..... if'n yer makin' a weight box so you can put lead in it why... not make it from steel and use less lead?

Edited Part - Should have read entire thread. Alan beat me to it.

you must mean 1/4-28..or 1/4 20....thers 5/16-24 nf....and 3/8-24 nf...but no 1/4-24..it was a typo?

It should have been 1/4-20.
Of course I had thought about using 1/4-32
but I could only find the tap.
Bill <><

Insert a 1/4 inch dowel into the tubing from the end away from the end you want to tap up to where the end is just short of the area that you want to tap. At the end opposite the end to be tapped, cross drill a 3/32 inch hole and insert a piece of 3/32 inch piano wire for a "T" handle to hold it with. By running the dowel the full length up to the threadded area, you avoid bending and kinking from the twisting. The dowel should be a slip fit but loose enough to easily insert and remove.

Bigiron

ok bigiron..that would work...but th hole he needs for a 1/4-28 tap is a #3 drill or a 7/32(.218)" or a #7 or 13/64(.203)" .... 1/4 (.250)" dowel wont fit....jim

Jim,

Well, it would start off as a 1/4" dowel. But clearly would need to be turned down.

OK, use 3/16ths dowel. It neednt be snug tight, just something in there to keep the bending and kinking down. As I said just slip inside the tube you want to thread.

Bigiron

1/4-32 is nef ...any machine tool supply will have em!!!

Hi Jim,

Unfortunately, I have not been able to locate any nylon socket head cap screws in 1/4-32.

Plus, we have no tooling/machineing parts specific shops anywhere near here.

What I am using now does a real good job as long as I can get the tubing threaded. 45 years of threading pipe, etc., taught me a lot, but this aluminum tubing is so soft that none of the tried and true methods will do what I want.

I will give Bigirons method a try next.

Thanks,
Bill <><

Bill,
This may or may not be an answer for you, but since you are making weight boxes, why not just considering brass tubing instead of the soft aluminum. It might be a problem in the tail if you are going to end up tail heavy, but in the wingtip, I would think it would be no problem.

I have used the weight tube alot--always used Brass 3/8. Use a tapered dowel plug. Has never come out.

I was of course talking about cutting those internal threads not tapping them!

And No, I don't think I'll try mashing it in vise over an ID piece.

USe brass for the weight box--ya need the little extra weight anyway!

ok smarty can u single point em...i can!!!!!

LAST EDITED ON Nov-17-04 AT 03:24 PM (CST)
 
bill... call bob or will @ 818-994-8063 screws are his business... they could tell ya where to find em ... jim

curt...why not clamp it in a vise as i suggested? u could put something between the tubing and th vise jaws if ur worried about scratches.... curt..do u see a problem with my simple solution ..if u do im all ears ...jim

No not really. But if the clearance on the ID part isnt quite tight, and you dont make the OD clamping arrangement basically into a "collet" arrangement, you still have a small contact area preventing the rotation--which is what you were trying to do in the first place.

And I think the potential for damage to the tube is still pretty high. Although it (damage) isnt a big concern for the weight tube application, in general, it seems the regular collet approach makes the most sense to me--but I have real collets.

It definitely isnt the easiest solution for sure.

Also, with the external collet, the collet can go completely over the area where you are going to produce the thread--whether you are cutting them on a lathe or tapping them--and this will prevent some of the OD expansion you will get otherwise.

I do frequently use the method of creating a wooden dowel based collet by simply boring the appropriate hole thru the dowel and putting it into a chuck to clamp the tubing piece. It works for facing the ends and polishing but probably would slip if a tap was used.

Anyway--whatever works for you. Thats the value of this forum--we can get several different approaches to solving a problem.

FWIW

LAST EDITED ON Nov-18-04 AT 05:32 PM (CST)
 
sorry about that snippy post curt....but th "mashing" comment kinda annoyed me...i was gonna suggest wood "soft jaws" put a piece of double back or carpet tape on each jaw take a couple chunks of soft hardwood maybe 1"x2"....say 4" long (vise jaw length)and close th vise on em ....open th vise put a piece 1/16 balsa between th wood jaws close vise tight drill ur tube dia hole through th center of th balsa...open vise insert tube close vise .... instant collette...and it wont scratch ur tubing...in case u wanna take it to th fair..ha ha ha ha...thats about th easiest thing i could think of...and wood soft jaws >~~wood come in handy for lots of other stuff u wanted to hold tight and not scratch...jim

Yes Sir:

I agree. I seem to spend alot of my construction time lately making these kind of special jigs and fixtures--my drawer is full of them--you'de think that after a few years worth of doing so, I would be able to slow down on creating new ones.

>Bill,
>This may or may not be an answer for you, but since you are
>making weight boxes, why not just considering brass tubing
>instead of the soft aluminum. It might be a problem in the
>tail if you are going to end up tail heavy, but in the
>wingtip, I would think it would be no problem.

Hi Alan,
I should have told the application in which I use these tubes.
I mainly use the aluminum tubing in the wing tips of my Classic I-Beamers. As you know, these planes were originally designed to not have tip weight. I have found that most of them actually need very little to make them feel good to me, but since I can't fly like Billy, or the late Steve Wooley, I need a *little* help sometimes.
A heavier tubing would be the way to go if more weight was going to be needed.
On the "new" ships I just use a box.
Probably just "out thinking" myself.
Thanks!
Bill <><

LAST EDITED ON Nov-17-04 AT 03:43 PM (CST)
 
im just tryin to help make things easy for ya...ive fabricated just about any thread u could think of...40 plus years as a machinist/toolmaker...teaches you a few things...jim
ps if "I" had a choice of makin threads of brass or aluminium ..id choose aluminium...for multiple reasons over your head curt

LAST EDITED ON Nov-18-04 AT 09:46 AM (CST)
 
...40 plus
>years as a machinist/toolmaker...teaches you a few
>things...jim

And I'm certain that you use collets on anything you can because you understand their value.

>ps if "I" had a choice of makin threads of brass or
>aluminium ..id choose aluminium...

AS would I...My use of brass tube is because I dont have to thread it.( for the weight tube application)

for multiple reasons over
>your head curt

You're making a pretty big assumption here! But I'll let it go as I hope you didn't really mean to be offensive.

Curt

Edit: Of course there alot of different alloys of aluminum. Some of the hobby varieties do not tap or machine well at all. They tend to being "sticky" and load up taps and cutting tools easily. THe free machining varieties and harder types do work well tho. The K&S aluminum tubing is very soft indeed and will be a challenge to work well.

And Jim is absolutely correct in recommending some type of cutting oil. For a easily obtained general purpose tapping lube on aluminum, WD-40 in a hand pump spray bottle like for window cleaner is hard to beat.

FWIW

>Hi Jim,
>
>Unfortunately, I have not been able to locate any nylon
>socket head cap screws in 1/4-32. :)
>
>Plus, we have no tooling/machineing parts specific shops
>anywhere near here. :)
>
>What I am using now does a real good job as long as I can
>get the tubing threaded. 45 years of threading pipe, etc.,
>taught me a lot, but this aluminum tubing is so soft that
>none of the tried and true methods will do what I want.
>
>I will give Bigirons method a try next.
>
>Thanks,
>Bill <><
>
>When the character of a man is not clear to you, look at his
>friends.
>Japanese Proverb

Ron B.
F4Fguy

Bill:

A lot of good suggestions here, but I think the real problem is the tap. The thread cutting operation has to have some tooth load(bite) to work. This requires more torque than the tubing can take.Try a thread forming tap or a 1/4-20 type "C" thread forming screw.These are designed to swage,not cut,threads.You're still going to need a mandrel of some sort though,to support the tube in a chuck or collet.

One way to do that, by hand, is to nest more tubing of smaller size 'til the tube will fit a piece of standard size, say 3/16" music wire.You can hold the mandrel together with CYA.

you could use whats known in th trade as "gun-taps" 2 or 3 fluted..but 4 flute will work if it has a long"lead"..known as as a "lead" or "starter" tap...tap it like this....a 1/4 turn at a time and back it off to break th chips...then another 1/4 turn...and so on till its deep enough...thats for steel ..aluminium u could prolly go at least 1/2 turn before u back it off and use some oil...cutting oil is preferred but any oil is better than none...back th tap all th way out a few times and clear out th chips...on brass...tap that dry it may "ceaze" with oil...in fact it may anyway...if ur tap is not real sharp...pay close attention to chip"build up"espeacially on smaller threads and you wont break as many taps or get rough threads...ive hand tapped 00-80s(watch threads)0-80s and 1-72s many times...in lots of tough materials using a blend of carbon tetra chloride or trichloroethane and white lead as a cutting fluid to keep th tap from ceazing...still think u know more about cuttin threads curt?...jim

>.in lots of tough materials using a blend of carbon
>tetra chloride or trichloroethane and white lead as a
>cutting fluid to keep th tap from ceazing..

.still think u
>know more about cuttin threads curt?...jim

Nothing here new to me sir..But I know enough not to be using Carbon tet or trichlor on anything at home.

I don't know how all this got going..I was suggesting a proper way of holding a piece of round material for threading or other operation..

And I offered that I wouldn't do it in a vise.

I live in Detroit man...every fourth person in line at the supermarket here is a toolmaker. We learned how to make threads as young'uns

I accept the fact that you are an expert at machine work. Please accept the fact that there might be others out here that know a little about it also.

Thanks

Somewhat reminiscent of the "Orginal Sparky" posts!

By the way... can I buy a vowel?

>Ron B.
>F4Fguy
>
>Bill:
>
>A lot of good suggestions here, but I think the real problem
>is the tap. The thread cutting operation has to have
>some tooth load(bite) to work. This requires more torque
>than the tubing can take.Try a thread forming tap or
>a 1/4-20 type "C" thread forming screw.These are
>designed to swage,not cut,threads.You're still going to need
>a mandrel of some sort though,to support the tube in a chuck
>or collet.

>Ron B.

Hi Ron,
I have found that the tap I use does *swage* the aluminum more than it "cuts" the threads.
The next bigger "nesting" size tubing will not take enough thread to hold a bolt.
will try and find a thread forming tap before the next time I do this.
Bill <><

>>Ron B.
>>F4Fguy
>>
>>Bill:
>>
>>A lot of good suggestions here, but I think the real problem
>>is the tap. The thread cutting operation has to have
>>some tooth load(bite) to work. This requires more torque
>>than the tubing can take.Try a thread forming tap or
>>a 1/4-20 type "C" thread forming screw.These are
>>designed to swage,not cut,threads.You're still going to need
>>a mandrel of some sort though,to support the tube in a chuck
>>or collet.
>
>>Ron B.
>
>Hi Ron,
>I have found that the tap I use does *swage* the aluminum
>more than it "cuts" the threads.
>The next bigger "nesting" size tubing will not take enough
>thread to hold a bolt.
>will try and find a thread forming tap before the next time
>I do this. :)
>Bill <><
>
>When the character of a man is not clear to you, look at his
>friends.
>Japanese Proverb

Ron B.
F4Fguy

Bill:

My suggestion was to "nest DOWN in size to a wall thickness which would allow chucking the tube in the area not being threaded so that it wouldn't crush in the chuck,in effect ,make a mandrel.
The thread forming operation doesn't cut at all, any, zero, zip.It has no cutting flutes,it simply swages the metal both ways(up and down)without removing any. You end up with a stronger thread and a thicker wall. In a malleable material like 1200(K&S Tube)Al it "works a treat",as our british cousins say. Remember, K&S 1/4 tube only has a nominal .015 wall,anything you don't cut is GOOOOOD. Another small point is that the I.D. of the K&S 1/4"(.0219) is very close to the reccomended drill size(.022) for a 1/4-20 thread formtap. As I said in my original post,a type "C" thread forming screw will also work very well. I've got a bunch of these from 2-56 to 1/2-13 that I've been using for twenty years for just this purpose.

Bill,

I use a 1/4/28 socket hed setscrew. I set up the threaded CF tube so that the setscrew bottoms out in the threading just as it is fully inserted into the tube. Allows you to torque it slightly so it doesn't spin out.

I've only used the nylon screws when I have pulled all the weight out and still need to dump a little tip weight. The nylon screws are a lot lighter than the steels I use.

Another trick stolen from the Fancher/Fitzgerald/Buck cabal. I made up a bunch of brass tube piece that just slide into the CF tube I use for the "box" and cut to length so that they bottom out in the tube and the setscrew backs against them. I put lead in the brass tube to a target weight. I have a pile of these from 1/8oz to 1oz. I just pull the plug, pull out the brass tube and go to the next lighter or heavier one. Whatever. Ted has this set up without the setscrew. He just uses a sort of interference fit so that the piece of brass tube is pushed into the housing tube on the end of the wingtip and pulled out by a little soldered handle on the end of the brass tube insert. I was too paranoid for this and used the setscrew.

Bill,

I do the same thing, but use CF tubing and a tap to make the threads for a 1/4x28 setscrew.

How do you hold it? Well, I just did this and have two heroic blisters on my hand from the process. So I guess the answer is "carefully"

Using a collet is the right answer.. If you grip the tubing in a collet with the end you are taping flush with the collet face it won't twist spin or otherwise deform.

Easiest would be to make one. a small block of aluminum would work great, as suggested drill a 1/4 inch hole roughly in the center of one face, then use your band saw to cut two slots + across the hole with out going all the way through the block. Clamp it in a vice and use a C clamp for the sides the vice isn't clamping.

LAST EDITED ON Nov-17-04 AT 11:21 PM (CST)
 
My 2nd hand Humongus had an aluminum tube tipweight box, came with it. I thought about it at one time, and figured a roll tap would be a good way to put threads in a piece of soft hobby shop tubing. I'd try just mashing 1/4" of the end of the tube in the bench vise and see if the tube would hold up to it. The mashed end is easier than plugging the far end, anyway. To tell the truth, I didn't like the setup all that well, but I am also a machinist with 30 years in the trade.

I have introduced roll taps to many shops (and recommended them here for some uses). Many were reluctant, most knew a good thing when they saw it. Still, not for every use, every material, or every part. They push a big exit burr, and if I'm going to have an access problem for deburring it, I don't use 'em.

A week ago, I had to make some crappy little (roughly .2 x .35 x .5) stainess parts and tap through them 0-80. I stuck an 0-80 roll tap in a 1/4" Jacobs drill chuck, used Moly-Dee tapping goo, and power tapped them on a Bridgeport, no problem. Unfortunately, these little stainless parts are still having effects on my fingers and thumbs. Hard to hold onto to deburr, and lots of burrs to remove after every operation. Had to do them in soft jaws in a 6" Kurt vise, and shop lighting is about like a romantic Italian resaurant. Steve

steve ..... we've all had those s@&%$y little parts jobs ...make ya punchy..i dont envy ya bud...dont want ur job...and after givin it some thought..oops noooo i dont know how to drill and tap 0-80 threads ...lol....carbon tet ...that stuff'll kill ya !!... mollydee works pretty good...i still got a small can...i go open it and put some on my hands just for th smell...it takes a couple days wear it off ha ha ha ha good smellin stuff aka monkey vomit.... heyyy how about those plastic reamer tubes some of th oldies even have screw on tops ...jim

I shouldn't have mentioned those little %@*&$+! parts...I got them back again yesterday. Of the two I originally made, they scrapped one in EDM, putting a .012" x .12 slot in one end (die sink). So, yesterday AM, they wanted 5, so I started on 8, and had them about 50% complete. Then they wanted 12, and EDM wants two setup parts, so I'm making 16 now. God, sometimes I really hate engineers...
The first batch, they gave me 3/8 sq. keystock to start with. This batch, that was all gone, so I am starting with 1/2 sq. keystock, and it's a bunch easier and faster. Actual finished size is .196 x .279 x .551, with +/- .005. EZ Trak SX...about 11 years old, and clapped. Steve

Hi Steve:

Yep..we've been using forming taps for quite a while now in our CNC machines. We do alot of small pneumatic valve bodies with stepped spool bores and tiny cover-plate tapped holes. Alot of our broken tool problems went away when we switched to formed threads. But we had to do a selling job on the OEM inspectors because they didn't like the thread tips with the "v" in the middle. Under the microscope they can always tell.

It always amazes me to watch these mills put in small tapped holes--drilling 1/16 dia holes .500 DP in 100 mSec! THen tapping it at nearly the same speed. Its pretty cool. With the forming taps, we didn't even have to step tap these holes.

Cheers

LAST EDITED ON Nov-18-04 AT 06:20 PM (CST)
 
ur right curt....it is amazing how fast u guys can make things...not like th bad old days....i used roll taps as far back as th mid sixties... but some materials were to abrasive to use em and they wont meet class 3 mil specs unless it says unj or j thread ok...has to do with th thread form...i imagine that is still so...have u ever heard of a relic machine tool called a "reed/printess"? its a thread rolling machine.... probably from th 20s or earlier for rolling od threads...but i think th "roll tap" came into being in th 50s or 60s at least thats th first i ever heard of em...they are only good for up to 50% threads 40% is th norm,...i believe a class 3 is 65% inspectors will bounce em on ya for minor dia os and burrs in th threads ....remove th burrs ..th hole is os....but things change ..that may not be so now ....jim

bob thats not a bad idea for one with some fab experience...actually one slit most of th way thru th bloc app. 1/8"-1/16" from th end would do...but u still need something in th hole with thinwall tubing or it will swedge...even in ur split bushing...jim

I use the Paper Tube that the cutting tools come packaged in for Wing Tip and Tail weight boxes. They work Great, come in a variety of sizes and glue really well. One tube just slides inside the other. The Plastic ones that Reamers come in have a nice little plastic cap. I use Fishing Sinkers and a little tissue paper stuffed inside like you were loading a muzzle loader. You can adjust were in the tube you want the weight to be.

You might be able to find a set screw to make a cap for your application.

Thanks Bob:

It's simple and it works because it is a technique that has been a standard for decades. Wont damage the tube and is simple enough to make as needed.

>
>I use 1/4 ID aluminum tubing, which I thread, to make wing
>tip and tail weight tubes. I cap them with 1/4-24 nylon cap
>screw bolts.
>
>Problem: I waste quite a bit of tubing trying to hold the
>tubing
> tight enough to thread it.
>
>Any hints??
>
>Thanks
>Bill <><

Cut a slot in the end of the aluminum tubing about 3/8" long with a hacksaw. Slide a 1/4" diameter steel rod up inside the aluminum tubing. Put a hose clamp on the tubing where you cut the slot and clamp it tight against the steel rod. Clamp the steel rod in the vise so you can thread the tubing.

Bill,

Square up a one inch block of balsa about two inches long. Drill the O.D. of the tube in the block on center lengthwise into the endgrain. (If you have letter drills, use a "D" as the hole will "Grow" a bit because of the endgrain) Take your tube and put half a dozen little dots of slow CA on the tube. Twist it into the balsa block with the end to be threaded flush to the end of the block. Grasp the block in your hand or lightly in a vise. Thread the tube. Split off the big chunks of balsa with a knife or chisel. Clean up the little bits with your exacto knife. Sand off anything else that remains.

I sometimes use the threaded maple wing mount blocks. Dremel one side out concave leaving plenty of threads and build a box about same.I use a short piece of 1/4 x 20 nylon screw with a slot cut in the top for a screwdriver. Steel BB's for weight.

Jim

>Bill,
>
>Square up a one inch block of balsa about two inches long.
>Drill the O.D. of the tube in the block on center lengthwise
>into the endgrain. (If you have letter drills, use a "D" as
>the hole will "Grow" a bit because of the endgrain) Take
>your tube and put half a dozen little dots of slow CA on the
>tube. Twist it into the balsa block with the end to be
>threaded flush to the end of the block. Grasp the block in
>your hand or lightly in a vise. Thread the tube. Split off
>the big chunks of balsa with a knife or chisel. Clean up the
>little bits with your exacto knife. Sand off anything else
>that remains.
>
>
>Kim Doherty

Kim,
That has to be the simplest method so far. A wooden collect, very simple to make. I believe it is the easiest thing for me to do!
I'm embarrassed!
Thanks!
Bill <><
When the character of a man is not clear to you, look at his friends.
Japanese Proverb

Get 2 taps, hold one in a vice and the other in a tap wrench, put a nut on each of the taps to define the depth of thread needed, put the tube between the 2 taps and rotate one. a thread will be cut by one of the taps until the resistance starts the other tap cutting. Continue to rotate the tap until a thread is cut at both ends and the end of the tube meets the nut on the tap. remove both taps and cut of the required length from the tube.

[photo not recovered: double_tap.jpg]

Picture posed by model

Regards

Mike

Just drill a hole thru the tube , making a "T". then you can put a piece of wire thru allowing you to hold it with you fingers. I have used this method but I use carbon fiber arrow shaft as it glues better.

DICK BYRON
3325 GALAWAY BAY DR.
GRAND PRAIRIE, TX 75052
972-336-0445
[email protected] (PAY PAL)There is an underescore between Dick and Byron ( _ )
http://www.dickbyron.com
"Adversity is the path to truth"
-Lord Byron

I don't understand why one would use soft, wimpy aluminum tubing for a wing tip weight holder. I use brass tubing. Heck, I need the weight out there anyway. Threading is cute but not necessary. I plug the end with a hardwood dowel of the proper size. Then drill a small (0.030") hole through the tubing and dowel. A straight pin through that and bent a little bit will keep everything in place.

Simple is best. Floyd

>I don't understand why one would use soft, wimpy aluminum
>tubing for a wing tip weight holder. I use brass tubing.
>Heck, I need the weight out there anyway. Threading is cute
>but not necessary. I plug the end with a hardwood dowel of
>the proper size. Then drill a small (0.030") hole through
>the tubing and dowel. A straight pin through that and bent
>a little bit will keep everything in place.
>
>Simple is best. Floyd

Hi Floyd,

This was from a reply up the thread:

"I should have told the application in which I use these tubes.
I mainly use the aluminum tubing in the wing tips of my Classic I-Beamers. As you know, these planes were originally designed to not have tip weight. I have found that most of them actually need very little to make them feel good to me, but since I can't fly like Billy, or the late Steve Wooley, I need a *little* help sometimes.
A heavier tubing would be the way to go if more weight was going to be needed.
On the "new" ships I just use a box.
Probably just "out thinking" myself."

Thanks!
Bill <><