Tube Forging

[macbruce]

Needing to make some legs for a small iron and wood bench I opted to do the bases of the legs with forged 3'' heavy wall tube to save on weight which was a requirement of my client. 3'' solid wound have been no problem for the 250# hammer but that powerful stroke isn't especially helpful when forging tube so the 50kg was used. The lighter faster blows get the job done faster with less chance of deforming the piece and the tubing needs to be coaxed rather than forged if you get my drift.....Parallelogram deformation must be dealt with often and easy does it.
I wanted the legs 3'' at the bottom tapering down to 1 1/4'' where they will be trimed back to 1 1/2'' then they will be joined with 1 1/2'' solid and continue tapering up to form arm rests and join with the back......Something to think about if you have a small hammer and want to make it appear you can forge bigger stuff. Unlike solid stock, the heavier the wall of the tube the easier it is to forge.....Gentle curves only....

[MOblacksmith0530]

Thanks for the tip. I have forged tubing before and discovered the "go slowly" rule. I didn't try thicker wall tubing though, I can see how it would tend to work better.
Interesting the way it fishmouthed on the corners. I noticed some of the same effect on the tubing I have forged in the past but hadn't gone half size. I have forged some 2" down to 1 3/8 before and 1" down to 3/4.

[macbruce]

I think I could have forged that piece on down to 5/8-3/4'', it's gonna split at some point...

[Fe-Wood]

This is something I have spent many hours pondering over the last few years I've wondered if filling the tube with fine sand and capping the ends would make it so it forged easier and could be drawn out and reshaped further. Anyone ever try this?

[bigfootnampa]

You will find that you rarely need to resort to things like sand fill. I forge tubing every now and then and I forge some pretty thin wall stuff too. MacBruce; It looks like you'll now have to cut off the end of that tubing and then weld some sort of foot on it?... so what if you just necked the tubing down to solid and then upset it back to make a foot instead of plugging in the welder? I've done that. If you wanted an open end but without the creep you could have just formed the end first. Then worked your taper back from that. Done in such a manner the tubing mostly thickens as you taper it instead of lengthening. I really LIKE forging tubing and with a bit of practice it is not nearly as difficult to work as most people imagine. Sometimes I have necked the tubing down to almost solid and then forge welded the pinhole shut to get a solid end. It takes some patience and perseverance to do that but it does work. I have also added a plug of solid metal and forge welded that in to get a solid end on the tubing.

[macbruce]

This is something I have spent many hours pondering over the last few years I've wondered if filling the tube with fine sand and capping the ends would make it so it forged easier and could be drawn out and reshaped further. Anyone ever try this?

Forget the sand, It might even melt and stick to the steel. Wall thickness is the key to success...It's like if you're gonna try forging 2'' sq, don't go with 11ga get the heavist, 1/4'' I believe....With pipe go with schedule 120, it's worth the extra $ cause working with stock that's too thin is a flail, doesn't mean it can't be done, it's just way harder.

[Alan Evans]

I found you can speed up the process by plugging the end of the tube with a rag or sometimes its even worth welding a plate over the end. It speeds up the heating and slows down the cooling. If you leave the tube open it acts like a chimney and the air passes through chilling the surface. Huge surface area with little thermal mass if you count both inside and outside surfaces. Plugging it you can halve the heating time and double the forging time per heat.

The weld on plate does not need to be continuous welded just needs to reduce the flow. I have a few plates with square stubs welded on which enable me to use smaller more comfortable tongs concentrically.

On some bigger tubes (around 200mm (8") diameter 10mm (3/8") wall) which we were heating and working on the last 100mm (4") we made up a plug from 40mm (1-1/2") ceramic insulation board mounted on a piece of studding so we could poke it down the tube till it was around the level of the furnace wall, that stopped the heat from travelling up the inside.

I have filled lighter tube with sand when bending hot and had no problem with it melting, you must make sure it is dry and I preferred to use wooden plugs rather than welding caps just to be safe.

I 100% agree that the thicker the wall the easier to work. The time you spend chasing your tail correcting cock ups and kinks seems to quadruple every time you halve the thickness!

[Alan Evans]

I wanted the legs 3'' at the bottom tapering down to 1 1/4'' where they will be trimed back to 1 1/2'' then they will be joined with 1 1/2'' solid and continue tapering up to form arm rests and join with the back......

On an aesthetic note will you be squaring/chamfering up the 3" end to get rid of the radiused tube corners or leave them alone and celebrate them?

Or are you cutting it at the spring line of the taper?

[macbruce]

On an aesthetic note will you be squaring/chamfering up the 3" end to get rid of the radiused tube corners or leave them alone and celebrate them?

Or are you cutting it at the spring line of the taper?

Since I couldn't know what the finished length woul be I deliberatly cut it long. The finished leg wiil not include any of the mill finish. The next piece of stock will get cut shorter cause I know where I'm at with how much it will draw.

[Alan Evans]

Since I couldn't know what the finished length woul be I deliberatly cut it long. The finished leg wiil not include any of the mill finish. The next piece of stock will get cut shorter cause I know where I'm at with how much it will draw.

How much did you forge and how much did it grow out of interest?

Oh and I forgot to compliment you on the taper! Edited June 27, 2012 by blackersmith

[macbruce]

How much did you forge and how much did it grow out of interest?

Oh and I forgot to compliment you on the taper!

It only grew 2''. Started with 12'' and wound up at 14'' with a 10'' taper. I think I'll lengthen the taper another 2'' from the fat end only. I don't to take a chance of crashing the tongs so I'll attach a porter bar. Grabbing that stuff with tongs on the outside edge is jumpy anyhow.

[Alan Evans]

It only grew 2''. Started with 12'' and wound up at 14'' with a 10'' taper. I think I'll lengthen the taper another 2'' from the fat end only. I don't to take a chance of crashing the tongs so I'll attach a porter bar. Grabbing that stuff with tongs on the outside edge is jumpy anyhow.

+1

The concentricity of your taper is what I was complimenting, and is the reason I remembered the advantage of welding a capping plate on the end which had a tong grab stub, bit of 25mm (1") square 50mm (2") long) it helped to keep everything in line. A couple of foot long stub equals your porter bar and you have the advantage of solid feel.

Not wanting to teach Granny to suck eggs, but if you do try plugging the end with the wet rag or plate watch that you don't get carried away and end up with three with a texture slightly different from your first one!

[macbruce]

+1

The concentricity of your taper is what I was complimenting, and is the reason I remembered the advantage of welding a capping plate on the end which had a tong grab stub, bit of 25mm (1") square 50mm (2") long) it helped to keep everything in line. A couple of foot long stub equals your porter bar and you have the advantage of solid feel.

Not wanting to teach Granny to suck eggs, but if you do try plugging the end with the wet rag or plate watch that you don't get carried away and end up with three with a texture slightly different from your first one!

I had'nt thought of the advantage of a full size cap helping with the heat, thanks. Messing with a wet rag doesn't appeal much to me unless the pcs were longer. A slight diff in the texture won't bother me or the client but if I put the bench up for critque somebody might rip me a new one.... B)

[Alan Evans]

I had'nt thought of the advantage of a full size cap helping with the heat, thanks. Messing with a wet rag doesn't appeal much to me unless the pcs were longer. A slight diff in the texture won't bother me or the client but if I put the bench up for critque somebody might rip me a new one.... B)

I cant remember where I first heard it, but I do remember remembering the tip the the next time I put my hand over the end of a piece of pipe that had its other end in the fire...ouch!

[2Tim215]

I forge all my tubing with sand fill and the ends welded shut. Splitting can be a problem with this method though so soft hits work best. I have found that on occasion I must empty some of the sand if I forge down to a long thin taper. Have made a few "Dr Zues" lamps this way.

[macbruce]

I cant remember where I first heard it, but I do remember remembering the tip the the next time I put my hand over the end of a piece of pipe that had its other end in the fire...ouch!

Let's not forget the ferocious blast of steam you get from the top end when you make the mistake of quenching the end(s). You'll only do it once........

[Alan Evans]

I forge all my tubing with sand fill and the ends welded shut. Splitting can be a problem with this method though so soft hits work best. I have found that on occasion I must empty some of the sand if I forge down to a long thin taper. Have made a few "Dr Zues" lamps this way.

Have you tried forging without the sand? What sort of size and wall thickness are you working?

Let's not forget the ferocious blast of steam you get from the top end when you make the mistake of quenching the end(s). You'll only do it once........

....or twice in some idiots' case who shall be nameless. (I gather) there was an awful "time standing still" type moment between putting the tube in the water and the blast whilst a nagging thought crossed the mind that there was a reason why that should not have been done! Hey Ho!

A really nice tale about tube forging I heard from my friend Andy Rowe. He did a working journey around the states a good few years ago. He worked with Clifton Ralph who was tapering round tubes using a vee shaped bottom tool which stopped it from squishing flat. He then went down to (Texas and Joe Pehoski I think it was) who had allowed one week on a job to cut out triangles and reform and weld tubes up to taper them. Andy showed him Clifton's trick, they did the work in two days so Joe said right we've done our work for the week I'll take you round and we'll go sight seeing!

[MOblacksmith0530]

I often cap the pipe when forging small hand bells to keep the heat in and prevent the steam jet when youhav eto chill the end for forging behind it. I once did that with a poor grip on the tongs and dropped it into the slack tub and it almost reached the ceiling when it shot back out, lessons learned.....

[GNJC]

Interesting to read that respected professionals such as yourselves have made the same mistakes as me (an unrespected amateur) regarding hot air first and steam later coming up a tube. I did learn after these lessons & only made each mistake once.

Blackersmith... I had that slow-motion thought sequence too, but - possibly even more stupidly - it came a couple of minutes after a hot air blast to the wrist. Who would have thought that steam would do the same thing? And I laugh at Homer Simpson's stupidity...

[Alan Evans]

Interesting to read that respected professionals such as yourselves have made the same mistakes as me (an unrespected amateur) regarding hot air first and steam later coming up a tube. I did learn after these lessons & only made each mistake once.

Blackersmith... I had that slow-motion thought sequence too, but - possibly even more stupidly - it came a couple of minutes after a hot air blast to the wrist. Who would have thought that steam would do the same thing? And I laugh at Homer Simpson's stupidity...

A wise man learns by his mistakes, a lucky man learns by the mistakes of others!

[2Tim215]

Have you tried forging without the sand? What sort of size and wall thickness are you working?

Yes, I do candle stick holders from 45x45x2 square tube, it always folds. The V swage or two pieces of 30mm round bar welded together work well. The idea is to have three areas against the steel tube you are working on. Problem with tube is once it folds it's very difficult to get out.

A lamp I did from 45x45x2 square tube with sand fill.