Tapered Stem

copperjoe - Wednesday, June 16, 2010 - 6:19pm

Hi, I am just going to throw this out there. I am trying to make a tapered stem from either copper tubing/pipe or sheet stock. I am trying to make Mushroom stems and I don't know of a good or correct way to do that. I have made a few and the problems that I have encountered are unsightly seams with sheet stock and I can't get enough taper with the pipe without splitting even though I am annealing through the process. I know that this is a elementary problem for some of the "Big Guns" on this site so I would love any suggestions that you could offer me on this problem.

Thanks in advance!

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I would use sheet and do

marilyn - Wednesday, June 16, 2010 - 8:00pm

I would use sheet and do anticlastic forming. You can make an anticlastic stake out of hardwood by cutting or filing grooves into the narrow edge of the plank. I reacommend Form Emphasis for Metalsmiths as a good book to get you started by Heikki Seppa. It's a paper back and not a newish book so it should not be costly.

marilyn

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Thanks Marilyn, I have

copperjoe - Thursday, June 17, 2010 - 3:39pm

Thanks Marilyn,

I have seen those stakes before but never knew what they were used for. I followed your links and have been enlightened. I never thought about trying to make one but now maybe I will.

Thanks,
Copperjoe

Can't never could do Nothing!

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I'd go with the tapered

Rich Waugh - Wednesday, June 16, 2010 - 9:34pm

I'd go with the tapered tubing/pipe, myself. That's because I'm a blacksmith and think in forging terms more than any other. Different strokes...

The trick to forging a nice taper in pip or tubing is to have the right tooling. You need a "V" block, ideally one with an included angle of 113 degrees - don't ask me why, but this ust works out the best, based on experience. Basically, one third of a circle or a hair less. When you place the pipe in the block and hit on the top of it, you are applying force in three equally-spaced directions at once, so the forces work together to compress the pipe circumferentially. This means a lot less distortion and therefore more effective forging.

Next thing to keep in mind is that you don't want the pipe to be too soft - if steel not too hot, if non-ferrous not dead soft annealed. When working copper it is too soft immediately after annealing so you need to go slowly at the start until it work hardens a bit, then you can hit it a bit harder until it gets too hard to work safely. Repeat as necessary. A lighter hammer is preferable to a heavier hammer - you're not working a solid bar, just thin sheet in a tubular form.

You can make your own V block with some scrap steel by welding it up, or you can forge one from a block if you have a power hammer or press. I've never tried a wooden V block for copper tube, but it might just work. If you try it, let me know how it works.

When tapering pipe, I work from the small end to the big end, usually. Work the end down to almost where you want it then start progressively working the taper back up the pipe to where you want the taper to start. I actually make my V blocks for tapering pipe so they have a taper to the V, as that assists in keeping the taper smooth. When the tapering is finished, planish the whole taper with the flattest faced hammer you can get away with using and you should be ready to file to a finished smooth surface in very short order.

Rich

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Rich, Thanks for the info.

copperjoe - Thursday, June 17, 2010 - 3:36pm

Rich,

Thanks for the info. I don't really know exactly what you mean. Having never seen a V block like your talking about, I'm not sure if I know how to use it. I took a piece of angle iron and cut it down to fit my pipe and have it clamped into my vise like an upside down V and am beating it that way. Is that correct? It is not working very well so I must be doing something wrong. Could you upload a pic or tell me what I did wrong?

Thanks,
Copperjoe

Can't never could do Nothing!

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Joe, Here's a quick

Rich Waugh - Thursday, June 17, 2010 - 9:19pm

Joe,

Here's a quick sketch of a v-block and pipe being tapered. I hope this makes my explanation clearer. It's hard to put things into words sometimes.

V-Block pipe tapering die

I neglected to mention that when using the V-block and hammer you continuously rotate the pipe while hammering it so you compress it consistently all the way around.

Rich

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Ah ha, I know what you mean

copperjoe - Friday, June 18, 2010 - 9:54am

Ah ha, I know what you mean now Rich. I think we were on two different pages. I was talking about starting with the smallest diameter pipe and trying to flair the bottom of the pipe out. You were talking about starting with the largest diameter and shrinking the pipe down.

Now, is there a way or tool to start with a smaller diameter and work it up to a larger diameter?

Thanks so much for all your help, I really appreciate it.
I am making my daughter a Alice in Wonderland Mushroom fountain for her birthday tomorrow. I have most of it made but are still lacking a few things and then I will have to assemble everything. Looks like it is going to be a late night in the shop again tonight.

Thanks,
Copperjoe

Can't never could do Nothing!

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If the pipe or tubing has

marilyn - Friday, June 18, 2010 - 12:18pm

If the pipe or tubing has thick enough walls, sure. I would anneal frequently and force something like a ring mandrel or whatever I found that was tapered and would fit. I would tap the mandrel forcing a flare and then remove it and anneal. You don't want to just hammer it in too far because it will be difficult to remove.

marilyn

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As Marilyn noted you can

Rich Waugh - Friday, June 18, 2010 - 2:28pm

As Marilyn noted you can force a tapered mandrel into the pipe to expand it. I prefer to use a mandrel that is slightly smaller than the pipe and forge the taper by using a small cross pein hammer to hammer the pipe over the mandrel. You line up the hammer face with the longitudinal axis of the pipe so that each blow stretches the wall of the pipe circumferentially. This allows you to make volute flares, as opposed to being limited to straight tapers.

Rich

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shrooms

dowpat - Wednesday, June 16, 2010 - 9:57pm

Do you have a photo or size of stem you are trying to do so we can get a better idea of you needs? I have made some out of large copper pipe about 1 ½” and just flair the bottom part by hammering it over a ball stake.
Pat

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Mushroom Fountain

copperjoe - Tuesday, June 22, 2010 - 8:17am

Mushroom Fountain: Alice in Wonderland Copper Mushroom Fountain

This is the completed fountain that I built for my daughters birthday. Everything is made from copper and then hand painted. The large mushroom is powdercoated.

Thanks, Copperjoe Can't never could do Nothing!

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