what's a reasonable amount of time to yellow heat?

[Adhamh]

Hi All,

 

I'm trying to estimate how long I should let my forge heat up and how long it should take for stock to reach forging tempatures.

 

I've setup a coffee can forge and BZ 8250 burners as per 

 

The kaowool has had rigizidizer and ITC-100 applied.  I'm in Austin which is about 600 feet above sea level.  I've estimated that my forge has a volume of about 16 cubic inches.  (its 2" in diameter and 5" on the inside of the kaowool).

 

When its wide open the 8250 will put out about 30 PSI.  Unfortunately, the regulator is not exact so I can't have it half open and expect 15 PSI.  (This is what an engineer at Benzomatic told me).

 

How can I estimate how long I should let the forge heat up before putting stock in?

 

How long should it take for the middle of a  3/4" round stock to heat up to yellow?

 

I fired up for the forge and let it warm up for ten minutes, then I stuck in the 3/4" round and let it heat up for 20 minutes ( I interrupted it once).  It maybe got to orange yellow, but was probably just orange.  I'm trying to cut the stock, and that heat really didn't get it done.

 

 

[ThomasPowers]

Sounds like quite heavy stock for a quite small forge.  Remember that the steel is conducting heat out of the forge too.

 

I often cut stock at "orange" with no issue.  How sharp an angle is your hardy?  I go for quite sharp angles and roll the stock and whomp it on each side and generally can get through stuff in one heat.

[Adhamh]

Sounds like quite heavy stock for a quite small forge.  Remember that the steel is conducting heat out of the forge too.

 

I often cut stock at "orange" with no issue.  How sharp an angle is your hardy?  I go for quite sharp angles and roll the stock and whomp it on each side and generally can get through stuff in one heat.

 

Yup, its heavy.

 

I don't have a hardy.  :-(  

 

I'm actually trying to make a hot cut out of this piece.  I'm using a wedge and really big screw driver to try and cut it.  Maybe its time to just hack saw it.

[EricJergensen]

What kind of steel? If it's sucker rod, 5160, or similar, it will be harder to get thru at a given heat than plain hot rolled. Same thing applies to shaping it. It will be pretty hard to move.

 

In any case, orange would be good enough for both. So, I suspect your wedge and screw driver approach. Go to the hack saw. (But make sure you don't quench the rod before you do. It'll eat up your saw blade. Let it air cool slowly.)

 

My forge takes 3-4 minutes to heat up 3/4" from cold. The core temperature will not lag exterior by much.

 

Given the small size of your forge, you may be losing a high percentage of your heat to the rest of the steel. It may heat much better when you have a hot-cut sized piece of metal.

 

If you don't have tongs and want to leave the bar attached, just cut part way. Leave something like the equivalent of a 1/4" bar. That won't conduct heat nearly as much and leaves you a handle.

 

Good luck. The "bootstrapping" phase can be frustrating.

 

Best,

Eric

[Adhamh]

What kind of steel? If it's sucker rod, 5160, or similar, it will be harder to get thru at a given heat than plain hot rolled. Same thing applies to shaping it. It will be pretty hard to move.

 

In any case, orange would be good enough for both. So, I suspect your wedge and screw driver approach. Go to the hack saw. (But make sure you don't quench the rod before you do. It'll eat up your saw blade. Let it air cool slowly.)

 

My forge takes 3-4 minutes to heat up 3/4" from cold. The core temperature will not lag exterior by much.

 

Given the small size of your forge, you may be losing a high percentage of your heat to the rest of the steel. It may heat much better when you have a hot-cut sized piece of metal.

 

If you don't have tongs and want to leave the bar attached, just cut part way. Leave something like the equivalent of a 1/4" bar. That won't conduct heat nearly as much and leaves you a handle.

 

Good luck. The "bootstrapping" phase can be frustrating.

 

Best,

Eric

 

good question.  I actually don't know what kind of steel it is.  I bought it from the drop zone and the only thing I remember was that it was hardened.

 

How could I determine more?

[ThomasPowers]

look up spark testing

[EricJergensen]

Thomas gave good advice.

 

Another approach is to just see how it behaves in heat treating. Start by checking it with to a file. If it is hardened, the file won't bite into it, but will skate across. (Don't try very hard, you'll just dull your file.) Find some non-hardened metal to compare (some angle iron for instance).

 

If it is hardened, can you anneal it? Heat it to orange and cool it as slowly as you can. I anneal in a 5 gal bucket of vermiculite (sold near potting soil). Leave it in for at least four hours. Check with file. If it is still hardened, you have some kind of air-hardening steel (examples: S-7, H13). Your best bet with this kind of steel is to not use it until you are more experienced ;-). But, you could go ahead and try. Cutting will be rough. It'll eat blades or take lots more hot cut work. Shape it, Grind it (filing will be nearly pointless, use a grinder). Use it. Don't quench it. Your main problem is that the hammering end is now too hard. You need to heat the hammering end to about 1300 degrees. Go for a dark-ish red. Air cool. Check with a file. Hopefully it'll feel softer (it won't ever be very soft like angle). If you go too  hot, you've hardened it again. Hard hammering ends are dangerous: they can shatter. Hammering on metal is always a bit dangerous. Always wear protective gear (eyes and ears especially).

 

On the other hand, if it is soft after annealing, now you can cut it will the hacksaw and go back to shaping it. Once you have the shape, anneal again. Then heat to orange and quench in canola oil (you'll need at least a half gallon). Temper to dark yellow. Better yet, read this http://www.bamsite.org/tips/heat.pdf

 

All that said, my real advice is get known steel. If you need to go cheap, at least get something where you're kinda sure what it is. In your area of the country, you can consider sucker rod. You can probably get some 3/4" for $5-10 (they're 25' long, so it's a lot of tools ;-) ). You'll probably end up with 4130. You can water quench that and temper to a light yellow. (Actually, you can just throw them in the oven @ 400 for 45 minutes. I have a thrift-store toaster oven I use for that.)

[Dodge]

Hi All,

 

I'm trying to estimate how long I should let my forge heat up and how long it should take for stock to reach forging tempatures.

 

I've setup a coffee can forge and BZ 8250 burners as per 

 

The kaowool has had rigizidizer and ITC-100 applied.  I'm in Austin which is about 600 feet above sea level.  I've estimated that my forge has a volume of about 16 cubic inches.  (its 2" in diameter and 5" on the inside of the kaowool).

 

When its wide open the 8250 will put out about 30 PSI.  Unfortunately, the regulator is not exact so I can't have it half open and expect 15 PSI.  (This is what an engineer at Benzomatic told me).

 

How can I estimate how long I should let the forge heat up before putting stock in?

 

How long should it take for the middle of a  3/4" round stock to heat up to yellow?

 

I fired up for the forge and let it warm up for ten minutes, then I stuck in the 3/4" round and let it heat up for 20 minutes ( I interrupted it once).  It maybe got to orange yellow, but was probably just orange.  I'm trying to cut the stock, and that heat really didn't get it done.

How long are you waiting now? As Thomas said, you have a large piece for such a small forge. In my opinion, I don't think you'll get to actual yellow heat on 3/4" stock...

[Rich Hale]

Ambient light is a big deal,,if you are inside a dark shop or outside in sunshine the same heat will be different colors to yoiu...and also wot you see as a collor may not be the same as wot I see.

Once you have some shop time can tell alot by how the steel moves at different colors,

[Bruno C.]

I think 3/4" stock is too big for your forge as well.   Do you have the end of the forge blocked off with something ?  Like firebrick or similar ?  That would help retain some of the heat.  Coat it in some ITC-100 as well, it would help some.

 

Yup, its heavy.

I don't have a hardy.  :-(  

I'm actually trying to make a hot cut out of this piece.  I'm using a wedge and really big screw driver to try and cut it.  Maybe its time to just hack saw it.

 

A hacksaw is a wonderful thing to have around.   But it sounds like have have limited tools.  I would suggest finding a cheap 4 1/2" Angle Grinder.  And some cutting blades for it.  I picked up a cheap ryobi from home depot years ago for less than you spent on the BZ8250 burner.  Also see them at pawn shops and the like.  The Ryobi doesn't spin fast enough, and it is not Recommended to use cutting blades with it, but sssshhhhhhh,  don't tell anyone, but it works for me, and has been for the last 4 years. :)   Just remember to think about safety all the time.   Sometimes a hacksaw can be quicker too, under the right conditions.   There also other ways to tackle the problem of cutting when using limited tools.

 

What kind of steel? If it's sucker rod, 5160, or similar, it will be harder to get thru at a given heat than plain hot rolled. Same thing applies to shaping it. It will be pretty hard to move.

....

If you don't have tongs and want to leave the bar attached, just cut part way. Leave something like the equivalent of a 1/4" bar. That won't conduct heat nearly as much and leaves you a handle.

 

What Eric said is very valuable and good information.  Keeping that in mind...

 

You can try:

1) Thinning out the area to be cut, then try to cut.  If you can heat it, you can hit it.  Draw it down or flatten out the area you want to cut down to 1/4" - 1/2" maybe.  Might help.

 

2) Go out to your yard or some place you can make a fire,  and make a bigger fire.  If you can get a hair dryer or some sort of air flow going through, you should be able to make a decent fire to work on your oversized piece.

 

3) *Danger Involved* (Eye Protection),  but depending on the steel, I've seen the smith's I've learned from use the edge of an anvil to cut through stock very quickly.  Hit the piece over the edge of the anvil as far down as you can,  then they would pour some water over that area (NOT THE WHOLE PIECE), causing it to cool rapidly.  Then they would simply break off the piece either by hand or on the anvil.  They were working with Mild Steel when they did this, but it can work for other steel if you are careful.

No Anvil ?   Whatever you are using, I'm sure it has a corner on it ?  Just make sure it's secured down to something solid and as immobile as you can get it.

 

4) Go to a steel supplier, and simply get the Right sized piece for the project you are doing.  This can save you time, frustration, and even money on Fuel cost's.   And, it will also let you keep going and continue with whatever project you are striving for.   Believe me, I have plenty of spring steel laying around, and been collecting it for years with grand Idea's of doing this, that and the other with it.  But I'll tell you what,  If I had just bought the right steel for my projects in the first place, I would have saved lots of money, time, and effort, and had more projects completed.    Now, I struggle to complete a home made Power Hammer, and mostly started building it so that I can work all of that spring steel down to what I need.   Again, cheaper and easier to just get what you need in the first place.   A hundred years ago, I imagine even a bad smith still had a team of strikers to help him accomplish his goals.  But his options were more limited then what modern day technology offers.

 

Good Luck, and don't Give Up.

 

-Bruno

[Frosty]

Another thought about heat times is how much interior volume the work takes up. A piece of 3/4" stock in that forge will take up enough volume back pressure will reduce the burner's efficiency and cause a lot of the fire to exhaust out of the chamber before it's done it's job.

 

A good boot strap hot cut is just sharpening a piece of leaf spring. You can cut leaf with a hack saw if you do before you heat treat it. If you have an anvil this will let you cut a shank that fits corner to corner in the hardy hole bring it up to non-magnetic, oil quench and you have a hot hardy.

 

Frosty The Lucky.

[Adhamh]

Thanks for all the replies.  You guys are great!

 

I got the piece cut.  Basically, I ended up tapering it and when it cut thin enough cut it on the edge of my forklift tine.  Its ugly, but it will work.

 

I'm basically convinced that this forge is awesome, for small work.  Even now I'm having a hard time punching and drift through a 1/4" think piece of flat mild steel to make some easy tongs.  It took several heats to get through.

 

The BZ 8250 died on me today.  It lets gas out, but doesn't light!  No spark or anything.  I'm going to consider upgrading to the "TurboTorch LP-1 LP CONTRACTORS KIT" that Larry talks about at the bottom.  Although at this point, maybe I just need to scale up to a 350 cubic inch forge.  Even though that seems way bigger than what I need….

[Frosty]

A turbo torch is kind of expensive but it's a heck of a torch and will be more than enough for a larger volume. It'll probably handle 350cu/in easily.

 

When you're punching stock that thin speed counts for a LOT, the steel starts cooling as soon as it's out of the fire and thin stock cools exponentially faster than thicker stock.

 

Frosty The Lucky.

[Bruno C.]

The BZ 8250 died on me today.  It lets gas out, but doesn't light!  No spark or anything. 

 

 Did you try a match ?   Maybe got some gunk in there ?

Might want to consider building something like a 1/2" venturi.  Ron Reil design seems fairly simple.  Or buy a good well made one. Like from Hybridburners.  I believe Larry Zoeller has some specs on a half inch burner.  If you build it yourself, the most expensive part is a good regulator and hose.  Need something between 0-30 psi.  Can prolly get away with 0-17 psi.  BBQ regulators will not work. Can also look up blown burners.  I've seen one made using nothing more than a propane torch (unlit), some pipe, and a battery powered mattress inflater for the blower. The torch provides the gas, the blower pushes it down the pipe, and it lights at the end of the pipe going into the forge. If you go that route though, be sure to do ALL your research if you wanna keep your eyebrows.

 

-Bruno

[VaughnT]

For a small forge, you can get an Atlas Forge burner w/ hose and regulator for $50.  

[damienfr6]

For a small forge, you can get an Atlas Forge burner w/ hose and regulator for $50.  

 

do you know how this torch works compared to...let's just say...a JF #1 burner, or venturi burner, etc.

 

those two burners will put you under $140...so I assume that they are more powerful. but i'm just curious if you personally know. :)

[Geoff Keyes]

Check out this thread over on the Bladesmith forum.  http://www.bladesmithsforum.com/index.php?showtopic=25573

 

I wrote this and I've personally built about 25 of these, plus been the guru for quite a few more.  It is a dirt simple blown burner.

 

Geoff

[VaughnT]

I don't have personal experience with either the Atlas or JF1 burners.  

 

The JF 1 is a very nice piece of kit by the looks of it - all stainless and adjustable air metering.  Of course, I don't know anyone that has one or done a review on them.

 

The Atlas forges and burners seem to get a lot of positive feedback on various knife-making forums.  While I don't agree with the design of the forge itself, the burner does seem to be a good value for what you're getting.  Again, though, this is strictly my opinion based on the reviews I'm reading.

[damienfr6]

I appreciate the feedback! :) I do have to say...i got the bernzomatic 8250 before I really did any research. I bought it for...$85. don't make my mistake. lol. I really wish I would have researched a little more. :)

[Chinobi]

im glad im not the only one with a BZ8250 NRFB in the garage XD but im planning to use that for small metal castings rather than the screw-directly-to-the-bottle model I presently use so not a total loss.

[BIGGUNDOCTOR]

It took about 15 seconds to get 3" of a piece of 1.25" round to yellow during a test of our 30kw induction unit.

[Chinobi]

That's just plain cheating =\

[BIGGUNDOCTOR]

Haha :-) It is pretty cool to just watch it get hot without any visible heat source-it's like magic.

If I was doing flat work like knives an induction unit would be the slick way to go.

We use ours for zone annealing electrical connectors.

[Jack Evers]

I'm surprised it took that long. 30 KW is a bunch of energy.

[BIGGUNDOCTOR]

The unit wasn't maxed out. We were not sure how it was going to react, so we played it safe. I would like to go in some weekend, and play around with it a bit to try some some different things.