Complete Beginner

[pnut]

I have read more than a few posts where the person says that they don't bother to harden and temper their punches and drifts. Just normalize and go. I'm just starting out myself so I'm somewhat confused about it. I've been reading up on punch making in the forums here and most agree that the punch just needs to be harder than the hot material you're punching through. I would err on the side of too soft vs. too hard.

Pnut

[Jon Kerr]

Ok thanks Pnut. I'm confused too.

Can anyone please recommend a procedure for normalizing (if necessary), hardening, and tempering a 4140 punch? (in laymans terms, please).

[ThomasPowers]

Well you are looking at a place where folks are trying to get the maximum price for their stuff; don't expect to find many deals.

I generally do better talking with folks to find the "I've had one of those; it's been out in the shed for decades---you want it?" deals.  Takes longer generally.  Sometimes other blacksmiths will help beginners along; just remember they KNOW what the stuff is worth! Jumble sales, boot sales---ask folks that have stuff that look like it comes from someplace that might have a hand crank blower if there is one at home.

Worst case scenario build a double lung bellows!  You can use tarpaulin canvas for the "leathers".  I liked my double lunged bellows better than my hand crank---just took up a lot of space as I couldn't mount it in the roof trusses. 

[pnut]

Everything I can find says 4140 is oil quenched. Quenching it in water may be the reason it cracked. I would try warmed vegetable oil and temper it fairly soft.  Will you be tempering in an oven or running colors

Pnut

Edited September 9, 2019 by pnut

[Les L]

Jon, I would not try to harden it and temper it. I would just forge it, lay it aside to cool and use as is. You're going to use it on hat metal and that will take your hardening and tempering out.

[Latticino]

I've done interrupted tip quenches for 4140 slot punches in water (a couple of seconds in then double that in air, repeat till looks black then abrade surface and watch for the temper colors).  Still prefer to quench them in oil with a full quench except the striking end.  I like my punches to last, and I have bent  longer ones in the past (particularly those with sections under 1/2" diameter).  Ideally I don't let my punches or drifts hot enough to lose their temper, except at the business end when they get stuck, or are going through especially thick material.  If they do get that hot I try to re-heat treat them.

[anvil]

9 hours ago, Latticino said:

I like my punches to last, and I have bent  longer ones in the past

I agree. I too harden and temper my hot work tools. The whole tool holds up better.

With 4140 I draw the struck end to a purple  after annealing and hardening to keep it from mushrooming quite so fast. The shank is usually annealed. The working end is annealed, hardened and differetially tempered to about a half inch or less to a straw on the tip. You will lose the straw, but the end is easy to reharden etc and the rest of the tool stays as is. 

The other reason is because you are new to heat treating and the only way to learn it is to do it. 

[Jon Kerr]

Thanks everyone for the advice. Think I'll go with Lattucino and Anvil's advice as, as Anvil says, I need to learn to heat treat anyway.

Anvil- So, for a 4140 punch- you are quenching only half inch on the tip? Do you use Water or Oil? Then quickly polishing and watch the colours run to straw at the tip?

I guess best practice is still to do as JHCC says and repeat the quench/polish/colour run until the colours stop running, to ensure the shank never gets hardened?

[JHCC]

That is  one option. Another option is to do a full quench in oil, and then heat the middle to run the tempering colors out to the end. A plumbers torch is good for this: it gives very good control, and you can heat the struck end a little bit hotter than the business to temper it a bit more and thus make it a bit softer.

[Goods]

Mark Aspry gave a demo at the IBA conference last year including punch making. I know he was using tool steel, I forget the type, but he would quench in water, moving the punch up and down vigorously. The last inch stayed submerged, while next half inch was moving in and out of the water to make a transition zone. He would the polish and let the colors run and repeat unit the heat was gone. He was also very insistent on heat treating punches.

[Jon Kerr]

Hi Goods- that's essentially exactly what I did (with the depths and movements exactly as you describe).

What I definitely got wrong was that I heated the material way beyond critical temp before quenching (I forgot the "non magnetic" bit.). I also didn't do any normalising after forging to relieve any stresses/ improve grain structure. It does seem from online research that 4140 requires oil, also.

 

I'm going to repeat my try; but this time, I will do a normalising cycle, quench in OIL at the proper critical temperature, and polish and run the colour repeatedly until the material has cooled. Hopefully this will result in no cracks!

 

I'd really like to get this right so I can work on a set of long lasting punches to give myself some options in future.

[Jon Kerr]

I've been struggling to find a nice (cheap/free) quench bucket for a while (with a lid, to stop the canola oil going rancid so fast).

Fortunately, I just sold the first axe I made, for £50! So I've treated myself to a very nice 25L (6 gallon) quench bucket with lid and handles (for £17. Gulp!).... and ordered 20L of oil to pour into it.

I'll definitely be making more bits to sell to fund my new habit....

[pnut]

Plastic wrap laid on the surface of the oil will slow down oxidation which is what causes oil to go rancid. You want to prevent the surface from coming in contact with air.

Pnut

[anvil]

6 hours ago, Jon Kerr said:

you are quenching only half inch on the tip? Do you use Water or Oil?

Not quite on hardening the tip. The end of your punch is tapered to whatever diameter the tip is. So bring the whole tapered portion up to just above critical temp. Critical temp is where you lose magnetism. Then quench about half or so of the taper in oil for 4140. Put it in vertically and move it up and down, not sideways. 

Now with sandpaper or file, quickly polish the taper good enough to watch the colors run. When you get the color you want and this color is about half inch long, put your tool in a can of water a bit more than half inch deep. This will stop the color run on the working end. 

This method is called the reserve heat method as you use the quench heat(in reserve) to run the colors.

JHCC's way works fine as well by adding heat after hardening. 

I prefer the reserve heat method as it saves a bit of time and there is no need for any other tools than your forge.

[ConstructionK88]

Ooo oooo I want my 2 cents in! My charcoal forge was approx 2ft long. The bottom was 3hole fireplace brick that served as the air inlet and tuyere. It was assembled in a V shape viewed from the front. The air ducted from under and expelled from the front and up throufht the 3hole brick which was controlled by bricks blocking the flow. I used small wood blocks as fuel and could adjust size by laying bricks flat on the bottom. The wood pyrolyized as I forged to charcoal. My fan was a central ac/heat centrifugal. It used an insane amount of wood but boy did it get hot. 

[Jon Kerr]

Last night I got back into the forge for a couple of hours which was great. Things have been busy lately and honestly, for a little while after getting the workshop and forge built I was a little burned out on shop-stuff! I turned my attention to some other hobbies/activities for a few weeks and my enthusiasm for forging has slowly and surely crept back in.

I never reported my progress from a few weeks back on my hammer rack. I was trying to achieve an all metal wall mountable hammer rack, and tried my hand at some mortise and tenon joins to hold it together. It was a bit of a disaster but I learned a lot.... In the end I think I'm going to give up.

Last night I didnt even think about trying the hammer rack again, and decided to have a go at a snail as a practice excercise.

My first 3 attempts were failures. I started with 8mm mild steel bar. Forging the taper, flat secton and antennas was all fine.

My problems started when I wanted to bend the flat section over onto itself to create the tail. On my first try, I marked out the bend on the edge of the anvil, bent it, and then proceeded to try and work the tail out to a taper. Pretty soon the bent section snapped off as I had thinned the metal in that region so much. I realised that it was likely I'd need to forge weld it....

I started again, and this time tried a forge weld. I failed. The metal was clean (albeit with a coarse flap disk), fluxed, but perhaps not hot enough? Was trying to avoid sparks but following a little research it seems that you need to be right on the borderline of sparkling heat in order to weld? Anyone have any other beginner tips?

Eventually the one I was trying to forge weld broke at the same position.

Third one failed as I snapped off an antenna while rushing and forging too cold.

By this point my piece of stock was getting pretty short from all the lopped off bits from each failure.... so I wanted to try one more time at forge welding. I skipped the antenas and went straight the the bend and weld step. I failed again, but this time I managed to get a bit of a taper forged on the tail without it breaking... so I finished him off with the spiral shell and did my best to hot cut and twist some very short little antennaes as the last step (which was awkward!).

Fun and games.... I learned a lot (dont rush! dont skip steps! dont forge cold!) and even failing to forge weld was an experience in itself I suppose. I can do some research to improve my chances next time.

[Les L]

Jon, cute snail, make some more and they'll get better with each one. Don't give up on the hammer rack, step back and identify the problem then identify what it takes to fix and finish it.

[Jon Kerr]

Thanks Les!

Yeh I won't give up entirely on the hammer rack. It's a little hard to explain without photos but the issues are fairly clear to me but also, unfortunately, pretty fundamental to my planned design and choice of stock. Simply- I need to mount my new leg vice as my old one isn't good enough. I also need to use thicker stock for the piece with the mortise in (relative to the tenon), as I was mangling the thin mortised piece while trying to heat and peen the tenon.

I might do a combined wood and metal rack to serve the purpose for now, but I definitely have plans to revisit mortise and tenon joints in future and put what I learned into action.

 

As for the snail, I'll definitely make more. Considering trying a design with a long spike on the bottom which could be stuck on a houseplant pot or such as a cool little ornament.

[Les L]

A snail made from copper wire would look good in the flower pots and you wouldn't have to worry about rust.

[ThomasPowers]

Nice idea.      On the other hand some plants profit by adding iron to the soil around them.

[Jon Kerr]

Last night's forging session was, again, incredibly frustrating.

I should be happy because, at least, the source of my frustration is changing which means I'm learning and the things I struggled with before are no longer a problem.

 

I constantly wish I had someone experienced to look over my shoulder and be able to point out the things I'm obviously missing and doing wrong.

My issue last night was trying to achieve a welding heat.

I simply can't get the metal hot enough without pushing it down into what I suspect is the oxidising zone.

Furthermore, I started to get some sparks above the fire last night without any steel in the fire at all, which I guess means I'm actually burning the bottom of my forge.

 

I'm using an Iron Dwarf bottom blast forge. As per the instructions (for using with coke) I have a shovel full of builders sand in the bottom (around 3/8 inch or 10mm)

I wonder whether my blower isn't up to scratch? its a proper forge blower but the back pressure of driving air through the small pipe and inlet hole seems to have it struggling, and you can feel a distinct breeze in the wrong direction if you hold your hand near the blower inlet. The pipe I'm using is the standard size supplied by Mr Iron Dwarf so it must be tried and tested.

I got down on the ground afterwards and had a look under the forge- theres definitely some buckling occuring from the thermal expansion and I can see what appears to be paint bubbling off (hope its this rather than burnt through already!). Everything was hot so I couldn't look properly. Tonight I will clean it out and inspect for damage.

Any ideas what might be going on?

Are there any dangers that flux/sand could cause to the bottom of my forge?

 

I tried some welding. Following Joey Van Der Steegs video with fluxless forging. I tried just bending a bar back on itself, getting up to heat (albeit, probably in the axidising region) and I think I managed one very short section of weld, twice. I couldnt get it to take further away from the bend. I did try fluxing too but it didnt help.

I tried a snail. Got the the forge welding step, messed it up, again, and broke it in half, again. I now have a total of 5 half-snails.

I then started working on another hammer-to-axe conversion, just to have some fun beating steel. Getting a large piece of stock up to forging heat was a challenge, again perhaps a lack of air?

[pnut]

Have you cleaned the grate or other inlets entering the firepot lately?  After you inspect it for heat damage check to make sure the air flow is unimpeded. Could anything have gotten into the outlet on the blower, like a mouse taking up residence?  

Pnut

 

[Jon Kerr]

Hi Pnut, thanks for your reply.

This forge design doesnt have a grate- it just has a single hole (15 or 20mm diameter?) as an inlet in the bottom of the forge. I make sure its clear before I build a fire each time, and I make sure its clear if I have to clear away clinker during a forging session.

The blower behaviour isnt new- its always been this way. The blower has a huge outlet (10cm x 10cm square) for which I have had to 3D print an adapter nozzle to fit with the 35mm air hose which came with the forge. 

[Glenn]

Check things from the blower, the air pipe, the air to the forge entrance, etc to be sure all are working and there is no obstructions.

Build a fire and this time make it 1-1/2 to 2 times deeper. Get a good fireball for the work you want to do. For your snail a fireball about the size of a softball or larger should do. This will have a good amount of fuel around and on top of the fireball. Fuel does not make a fire  hot, air makes a fire hot. You want just enough air to get the heat you need from your fuel.  You may be surprised just how little an amount of air this takes once the fireball is established.

Rethink the procedure for making the snail. If you want a weld at the fold, (it is not necessary) then learn how to weld in the fire. For mild steel, put two pieces of metal into the fire and bring them up to orange heat. Wire brush them clean and return them to the fire. They should be 1/2 to 2/3 up the fireball. Bring the heat up to yellow and just tough the two pieces of metal together. If they stick to each other, you have a weld. If not then increase the heat and try again. When they stick to each other you are at welding heat.  If you are throwing sparks from the metal, it is too hot.

Heat and make a fold in your metal. If you want it welded, see the above for the right heat. If not then proceed to the next step.  Roll the snail shell up from the hot long end toward the body. Hot just makes it easier to roll and makes a tighter roll.  Do not roll it all the way up but leave a couple of inches straight.  Bend the straight end so the snail head is out of the way and can be formed. The shell can be clamped in a vise is needed while you form the head.  If you make the head stock a little long you can always cut off any excess of antenna.  If the head is too long, then split it deeper and rework the head.

Now that the head is to your liking, heat by putting only the fold and shell into the fire and continue rolling the shell.  If need be put a little water on the head to cool it down.  

You already know all this, but may be overlooking the obvious until you read it.  

Another way to improve your technique is to make a story board, that is to say make one example for each part of the snail. Then make a second story board. You will end up with 5 or 6 partial snail parts. Next make part one and place it aside. Then make part one and two and place it aside. Then make part one, two, and three, and place it aside. etc. There will be a complete set of maybe 15 - 20 steps when you finish. All this gets you to thinking about each step, how it is made, and then how it is progressively put together. 

BTW, mig wire makes a nice antenna for the snail.    

[Jon Kerr]

Thanks Glenn- as always a really informative post.

I'll have another go at welding as you decribe (both your method and description of fire bowl). Thanks for that.