How to make this?

[khan]

If you needed to make this shape. Say 18" long and 1" dia. at the ends and 3/4" in the middle. What would be the best way to make it without getting lumps and twist. A smooth length tapering in the middle as is shown in the sketch.

Does anyone have ideas?

Thanks for any ideas you can share.

Khan
40229

[VED]

if it has to b exact use a lathe and some dial calipers if not heat up a big chunk of 25 mm and strech the middle to the desired diamerter

[khan]

So you mean you can heat say 12 or 14 inches of 25 mm to and even heat so it would stretch without any lumps or variations? that is alot of tube to get exactly hot to do the pull... do you understand the problem. If you heat a short piece it will come out like a point.... skinny in the middle. So i donno.
Khan

[metalbone]

there are ribbon head atttachments for Nationals that can heat up large lengths of glass, Ive seen 4, 6, & 12 inch ribbon burners.

[CripSkillz]

Heat Tube and Pull??

[BK]

So you mean you can heat say 12 or 14 inches of 25 mm to and even heat so it would stretch without any lumps or variations?
Khan

yes, of course you can. soft heat, even application

it may take you a few tries but its completely and entirely possible

[Monkythrowpoop]

If you're feeling iffy about heating up a large length of tube, heat up a wider tube and just pull it down. Just heat the whole thing enough to get a good stretch. Remember to have beefy handles so you can sink some good heat in. Either way you'll have to focus on an even heat base. Then for the finish I'd say flare one end after the pull, let it cool, hold it by that and finish the other end.

[Logan]

If you have an adequate torch and a proper understanding of heat base you can certainly do it. Knowing how to work the angles of the flame is also important when heating sections that are much longer than the diameter of your torch.

If it were me I would make it in 2 tapering sections and cleanly weld them together in the center.

[Logan]

Just curious, what are you making this for?

[khan]

It is a connecting piece in a scientific apparatus. Ive made many many of them just using a straight piece of tubing and it works fine but since ive gotten making them down pretty much not im trying to make them look better and the smooth constriction would set the thing off just right. It bothers me seeing that straight tube ... it seems to be begging to be made nicer with some shaping.
I guess i look at my scientific stuff just like some guys look at their pipes. And how i look at the pipes i make for that matter. As a work of art that is funtional too.
The ppl buying these are modern day alchemist and they appreciate glass that looks from the 16 century
Thanks to everyone who put in some thoughts. Im thinking the best way to approach it is with the ribbon burner tip for my national or maybe 2 of them side by side to get a nice long even heat base. The pull will be easy if i can get the heat just right.

Khan

[gambitglass]

its a one inch tube, that doesn't seem too heavy duty to pull off. Its seems a bit mathematical to me. I would set it up with the cut ends being the ends of course and fire polish them and let them cool. then you have to play around until you can figure out how much it will stretch to achieve the taper in the center. I would guess at least 4-5inches will be gained in the stretch so figure on 14" maybe? then I would try and really softly and evenly heat the better part of the middle of the tube and stretch it nice and slow likely holding one end vertically while spinning and letting it fall a bit them flipping sides and dangle the other end until the taper is nice and smooth. you'll probably need some kind of handle though because heating 10" of a 14" tube doesn't leave much room for hands, maybe you can cork both sides with some kind of rod epoxied into the corks to hold while spinning. I'd figure on playing around with 4-5 attempts until you figure out how much glass you will need and how much heat and pull you will need to stretch it just right. good luck

[VertigoGlass]

If you have a lathe and need to make a lot of them. I would use a draw bar and a graphite profile plate.

[D. dino i ninjah]

pull a point on 55 mm and make it extra thick then flame cut ends is how id start out.
Some people pull stringers little bitts at a time others melt up big ball and pull Im part of the latter group
ooh waight snap

Take 3/4in tube cut 20in section melt end and blow out flare type bubble 1in in diameter now flame cut lip
and allow to cool and then do the same thing to the other side
essentially condensing the 20in tube to 18in while flaring the ends and eliminating the need to pull a perfect pull
sorry I just love the brainstorming

[VertigoGlass]

If you only have a few to make and a lathe a simple hard wood profile paddle kept soaking in a bucket of water would do the trick. start off with 22 mm tube heat one side block and blow paddle in the bucket. Heat the other block and blow flame cut or saw cut the ends to final length.

[khan]

I do absolutly love to hear you guys brains working on this little problem... it is so kool to hear how you approach the problem ive been torturing over for some time now.
All the ideas are good but i cant help but wonder which ones would work and which ones wont. If anybody has the time and wants to try it would be incredible to see a pic of the results. I have been working on it from time to time but my results arent worth posting ... yet...
Its just one of those things that wont leave me alone... so i guess i will do it but im still not sure how yet...hehe

Khan

[Melt Man]

maybe if your kiln is big enough rig out some steel wire and fire the thing to a high temp with the tube being supported by the wire at the top hanging vertically if all else fails, but I do like the idea of just pulling out a wide diameter tube to your desired result the best. Try to "slump" the thing into shape if all else fails. Pull it out of the kiln and then flare out the ends to your desired diameter.

[Dom]

Dude... this is easy as shit.. Just take a piece of 50x5 or 44x4 whichever is more comfortable for you. Heat a section and stretch it out to the size you want... Im sure itll take a few attempts.. so good luck :)

[Mecha]

^Seriously.

Heat larger tube with torch, stretch tube. That's it. This is one of those things were understanding your heat base is crucial. Actually, if you want to do anything right, understanding your heat base is crucial.

If straight tubes were working fine then I imagine that the only important tolerance to meet is the ends.

Just have a go at it. You can practice with smaller stock until you get the concept of heat distribution and how it will affect your pull. Then just try to scale that up.

[khan]

Mecha i think your probably right. I may have to put some smaller diameter "handles" on each end of the large tube so i can spin it and have more control of it in the flame. It is for sure going to take some think wall ... the thicker the better i guess. So when its pulled it doesnt get to thin in the middle.
And yes the dimensions are not critical but have to reasonably close.
Thanks
Khan

[VertigoGlass]

Making 5 pull by hand 500+ of them the same draw bar profile plate

[khan]

Absolutly VertigoGlass.... the proof will be in the doing.
I am not sure it will be worth it to change if the setup time and material cost is much much higher than what im doing now. But i still would like to do a couple to have as examples and just to know i CAN do them if i want to..... say for a special order.
Khan

[MUPH]

Pull from a 1" tube

[jseden]

this seems like a lathe or long ribbon burner job.. or both..


how critical are the taper dimensions? is sealing a piece of 3/4 between two pieces 1" an option?.

I like Dom's answer too

[MUPH]

I don't even understand why this is still a topic of discussion. It's a simply taper

[VertigoGlass]

Because ben thats what threads like this are for finding multiple solutions for a problem. Depending on the tollerance i highly doubt that if you were working from a print with tollerance and in production that you could ever pull these tapers consistently with repitition in reguards to dimentions as fast by hand as with a profile plate and draw bar on a lathe. I guess because you spoke on the subject the thread should be shut down..... MURPH fur PREZ!

[khan]

No, Ben its not just a simple taper. Did you read all the post about the problem? The thing is you only want the center to be about 1/4" smaller than the ends in dia. And the whole thing is about 18" long.
So you would almost have to evenly heat about 14" or 15" of tube and pull it the other 4". If you heat less length then when you pull it out to 18" its going to much smaller then 3/4" in the center. If the heat isnt perfectly even on that 14" then when you pull it there will be ugly lumps and not smooth.
If im missing something and it IS just a "simple taper" then please do one and take a pic of it so we can see how easy it is to do. By all means please show us how easy it is.

[Matt P]

yeah pics or gtfo!

oh wait.... I'm not part of this thread... and could never pull this off....

woops :o: don't mind me....

[MUPH]

Because ben thats what threads like this are for finding multiple solutions for a problem. Depending on the tollerance i highly doubt that if you were working from a print with tollerance and in production that you could ever pull these tapers consistently with repitition in reguards to dimentions as fast by hand as with a profile plate and draw bar on a lathe. I guess because you spoke on the subject the thread should be shut down..... MURPH fur PREZ!

Settle down.

You have the same answer multiple times, practice. Its not going to get any easier sitting in front of a computer screen. Throw a 3/4" graphite rod down the tube to prevent the taper from going under 3/4" ?

[VertigoGlass]

The first thing about this is the sizes. When talkin about a taper over 9 inches from3/4 up to 1inch its an 1/8th inch per side over 9 inches which is pretty minimal. Now i did one side at a time but if you were really goining to make this i would think you would make a one piece pattern. I took a broken graphite paddle and carved out a random profile of no nominal size draft or taper and didnt finish it of that great due to not wanting to waste a ton of time on this. There are a couple weird places in it which are transfered from lumps in the pattern but could easily be fixed of this was for a real deal. The ends are crisp and sharp and would allow you to either ring seal up to them or cut to a nominal length on a saw without losing any diameter from hand pulling. This was done by hand with holding the pattern up agains the glass with vice grips. A make shift draw bar could be made and bolted to the fire carriage of any lathe and repeatabiliylty would be amazing. This piece is about 12 inches long and all done with a hand torch on 22mm tubing. Total time invested including profile plate 10 min. http://i625.photobucket.com/albums/tt332/VertigoGlass/Mobile%20Uploads/2012-08-10_13-25-46_68.jpg

http://i625.photobucket.com/albums/tt332/VertigoGlass/Mobile%20Uploads/2012-08-10_13-26-08_728.jpg

http://i625.photobucket.com/albums/tt332/VertigoGlass/Mobile%20Uploads/ResizedImage_1344630441872.jpg

[khan]

Thats damn amazing Vertigo. Im thinking that method is the one of choice especially for the repeatablity.. I dont think it can be beat..!!
And yea a one piece pattern would be the best way to go.
I was thinking that if you did HAVE to pull this shape the best thing to do would be to gather the glass .... say the middle 10 inches by doing marieas and melting them in... then when its gathered into say 5 or 6 inches i think you could heat the whole thing and pull it............
.....maybe...
thanks for all the input to all

Khan

[VertigoGlass]

Its not a complete smooth taper but like i said any imperfection in the profile block will tranfser to, Even scratches.

[kc-216]

heat it slower and get an even heat base throughout the middle and do one even pull. lumpyness=uneven heat

[khan]

yea Vertigo and those small imperfections could be taken out if you wanted to take the time.

Khan

[VertigoGlass]

If it was for a real part i would write a program in cad and cut the profile/taper on my cnc then polish the graphite. Since the graphite would be considered a consumable and over time break down and lose its tollerance being able to repeat the profile plate would be important to me as well. I love brainstorming think tank round table discusions like this. There really is no one right answer as the variables on quantity tollerance repeatability ease of process and so on are too great. Things like these are what lead me to building my own lathe in the first place.

[khan]

I would really like to see some pics of your lathe Vertigo... Ive thought about it myself but never got a start..
yet.

Khan

[Aymie]

You should be able to do this without a lathe. If you can't, get off the computer and on the torch. This is simply pulling down the middle of a tube. It's a half step above basic prep.

[VertigoGlass]

Cool aymie, i will be checking back to see your pics of a 1/4 inch taper over 9 inches and repeating the same over the next 9 inches and keep the tollerance and repeat it a couple hundred times.

[khan]

Ill be looking forward to seeing that too....... Would be great to be shown how that is done.

Khan

[Eric S]

its interesting how worked up people are getting over what is essentially nothing. vertigo has shared interesting methods to get something highly repeatable, but as the OP has already mentioned, this taper serves absolutely no function other than aesthetic. this means that exact ratios of lenght/width dont need to be repeated, because they dont matter. as long as the tube is 18" long, and 1" long on the ends to meet with the rest of the sci apparatus, without the taper constricting too far to impede the flow any piece of 1" tubeing with any degree of melting/point pulled in the middle will work.

i

[khan]

I donno about anyone else but i dont feel "worked up"...hehehe
Just a good lively discussion is what i see.
i enjoy talking about problems in glass blowing... thats what this place is for isnt it?

Khan

[MUPH]

Cool aymie, i will be checking back to see your pics of a 1/4 inch taper over 9 inches and repeating the same over the next 9 inches and keep the tollerance and repeat it a couple hundred times.

Why is it anyone who provides an answer to the question is expected to post pictures of it?

[VertigoGlass]

Because until you have aqntually trie it done it and have something to show all you are is a keyboard jockey. As yoy said something like get off the computer and do it... i did it posted pics and proved my method with a little refinement would work great. I just want to see you pull a consistent 1/4 inch taper over 18 inches by hand and repeat it a couple hundred times.

[MUPH]

Vertigo you obviously have some personal vendetta here. Khan has received the same answer from multiple people over and over and over again but yet you're the one making a fuss about my response. Khan has the answers but you keep dragging this on. You're the only one who posted pics so you're the only one who's more than just a keyboard jockey.. let it go man

[Aymie]

It can be done by hand but I have no need for this item, therefor no desire to waste work time making one and posting a pic. Just because I won't show you it doesn't mean it can't be done.