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I could use some advice with upsetting the middle of a 3/4-inch bar.

First problem is that I have a propane forge for knife-making (interior 4" x 4" x 20") so I cannot spot heat the middle of the bar.

I end up heating 8" to 10" of the bar, so when I try to upset the bar it just bends no matter what I try.

I have tried holding the bar at the 4" x 4" opening to spot heat, but the bar just doesn't get hot enough.

 

 

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Water quenching spring steel will harden it maybe too hard. Normally I just break out the torch but there are other alternatives. If you have any you can wrap the sections you don't want hot in Kaowool.

Another method is to use chill plates or bars. Chill plates are usually copper plate or bar used to stop weld beads but they work a treat for cooling a specific area. Aluminum works well too but even steel will do the job. For example lay two pieces of heavy as you have steel on the bench with a gap a little longer than the section you want to upset. The vise jaws will work a treat for one side. Lay your bar on the plates and lay another one on top. 

A little creative clamping or spot welding on the main chill plates can make guides and help prevent the bar bending. 

This is a perfect example of why it's not a bad idea to have a solid fuel forge available. I like the duck's nest in my old buffalo pan forge. I form up the fire "pot" with fire bricks and it's really easy to place bricks with a narrow gap the bar barely fits through for the sides and the space between the sides being the distance I want heated. If all you're doing is bending, twisting, upsetting, etc. briquettes will do the job, just break them into acorn sized pieces. Not ideal but you don't need clean charcoal for this kind of process so you can save yourself a buck.

Frosty The Lucky.

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"I can still water quench and anneal after upsetting?"   

Bad idea..... you will be hitting hardened untempered steel. If you could interrupt your quench before the steel got below 400F you would still have mostly austenite, but martensite would be forming as the steel cooled, like at the face of the anvil. 

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I personally do not know if quenching higher carbon just enough to not move like the localized spot would be at risk of cracking or breaking. I'm thinking it might be ok if you just took it down to a dark red other then the spot to upset.  Other then that maybe it's a job for a torch. 

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Buy quickly quenching I meen down to bull red just above black, the quenched area should temper from the heat especially if you have the inside nice and hot

Another option is to build a heading plate for your vice and then you only heat the one end, if you punchthe plate hot with a tapered drift then the upset won't be as lopsided. And you can repeat with the other end to even it up

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1 hour ago, swedefiddle said:

Good Morning,

Heat the small area with a Rosebud.

Neil

I tried with a Propane torch but that was a joke. I see that I'm gonna have to upgrade my shop a bit.

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Good Morning,

Oxy/Propane works well. You need to buy a tip for it, it is a different tip than Oxy/Acetylene.

Propane by itself won't have the concentrated heat.

Neil

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If you dont have an O/A torch, then my first thought would be to just make a solid fuel fire. You dont need a perfectly designed forge to heat steel. You can literally start a campfire, let it burn down to coals (or just start with charcoal) put the section of your steel into the fire that you want to heat, and use a blowdryer for air. Or a large flat board as a fan. Or your lungs. Voila! 

Like Glenn says, if you never build the box, you never have to think outside of it. 

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Two things, 

 

1: a local quench from a water can needs only bring your bar down from a good yellow to an orange or red.  The residual heat will bleed in as well, so no hardening, tempering etc will take place.

2: this may sound counter productive but works.  Compliments to Francis Whitaker for this one.

 

Use a lighter hammer. 2-1/2* or smaller even for 3/4". A larger hammer will transmit too much force and cause the bend in your bar.  A lighter hammer will upset without the loss of force to bending.

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How long is the bar?  Is it possible to use a long bar and then cut the part you don't need after upsetting?  The reason I ask is using the rest of the bar as the anvil  or as the hammer works really well and you get less bending than if you back the bar up and then hammer it.    Striking the end of the bar with it just laying across the anvil and you holding it rotating a 1/4 turn every blow works well for upsetting the middle of a bar.  You do need enough on the opposite end to provide some mass.  The other way is holding the bar and driving it into a heavy  plate or anvil on the floor.  2 of us taking turns upset the middle of a 2" bar to almost 4" square using this method.  Again rotate 1/4 turn every blow to help keep it straight.  We left extra stock on the bar to act as extra weight and a cool handle.  Once we were done upsetting we cut the bar down forged the ends and bent  in the middle of the 4 in section.  Bending it 135 degrees thinned it back out to around 2 in square again. 

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Like Charles suggested - can you take your propane burner out of the forge and use it like an oxy/acet rosebud? Clamp it in a vise and hold the coil spring in the flame?

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I wonder if a tube steel solution would work? Most people have some steel tubing lying about if you notched out a place in the middle then placed that just off to the side of your burner perhaps you could heat your target area while providing a minimal heat shielding to the rest of the piece?  Not having a gas forge I cannot even try it but on my coal forge to focus a special heat to push up a handle stop on a chisel I used two pieces of mild plate to block the heat and oxygen from the surrounding coal to either side and focused the heat a bit.  In my case it was a partial success since the heat wasn't as confined once the plates were heated for an extended time.  Just not sure how effective it would be on a forge reliant on forced air for heat.

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I was at a Francis Whitaker workshop once, and a guy said that when he started to collar his scrollwork, there wasn't enough room (daylight) to slip the collars on. Francis said, "Then your design is wrong." Now about this coil spring upset, is your design wrong from the git-go? Can't you use mild steel so you can quench without worrying about hardening?

Something I heard a few years ago, "Never more than three." They were referring to the heat length being never more than three times the thickness or diameter of the stock you're upsetting.

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 A coal or coke forge is easier to control to get a localized heat in the middle of a bar.

There's less time wasted cooling the rest of the bar from the long heat of a gas forge. 

Upsetting works best with a high heat, more so than for drawing.

For short  localized heats, I find that a big oxy fuel cutting tip [ #2 or 3 ] works better than a rose bud and consumes a lot less gas and gives better control.

Having your torch run through Gas Saver is much more efficient and will pay for itself quickly in gas savings and reduced frustration.

Good ones are made by Smith or Victor

These are a shut off valve installed inline between the tank regulators   and the torch. The torch is connected to the gas saver on the outlet side by a pair of short flexible hose whips.

They have a pilot light  built in . Set the mix on the torch, heat the part , hang the torch up  on the hook which shuts it off, do the work , pick the torch up  again , light on the pilot and reheat as needed.

Once the mix is set on the torch there is no time wasted adjusting the knobs or shutting the torch off and setting it down while the part cools.

These are designed for different fuel gasses and also work well with a brazing torch or an oxy propane rosebud tip up to a #10 for larger heating jobs.

These are well worth the money. Fabricate a stable stand for it so you can bring it close to the work. 

A decent welding supplier will usually have them in stock and can make up the short hose whips .

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1 hour ago, Frank Turley said:

Now about this coil spring upset, is your design wrong from the git-go?

How about the easy solution: Get some medium carbon stock that is already the diameter that you are trying to upset to and taper each side around the center.

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 We all like gas forges because you gan get a long even heat on whatever will fit in the firebox.

Has anyone successfully built a  gas forge specifically designed for a short intense heat  in the middle of a bar ?

This is probably one of those applications where an induction forge would really be the ticket.

 

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"Has anyone successfully built a  gas forge specifically designed for a short intense heat  in the middle of a bar ?"

It's called a torch and they have been around for over a century.

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