Hot cut hardie

[M.G.]

Made my first hot cut tooling for the 1" hardie hole on the Trenton today. Well... I got through the normalizing cycles. Ill get it ground and heat treated tomorrow afternoon. Started with the shank end of a jackhammer bit of which I made a hammer eye drift from last week. 

As always, feed back and thoughts to chew on are always welcome and appreciated.  

 

 

[JHCC]

Looks good. My only suggestion is either (A) temper it on the soft side or (B) do your cutting with a soft hammer. Both of these are just fine for keeping the edge of the hot cut undamaged.

[M.G.]

Excelent, great advice. I was thinking a softer edge would be ideal, I left excess height taking this into account, so as I dress it over time I can later upset and reforge the cutting end of the tool. 

[ThomasPowers]

Mine is made from a jackhammer bit too.  It was the broken off tip that I forged down what was left of the shaft to fit the hardy hole; been using it around 20 years and it's shrunk at least 1/4" so far from sharpening.  I would like to point out that resharpening the hardy is a trivial task compared to redressing a hammer face.  I actually hand students a harder hammer when they go to cut if their hammer control was so sloppy I had given them a softer hammer to use forging.  (I have one dead soft hammer that I "suggest" to folks who hammer like lightning---never hitting the same place twice!)

[M.G.]

I definitely feel thats the way to go. I would much rather damage a hardie tool than my hammer face.

[JHCC]

Quick tip: when you're cutting a piece to length on the hardy, cut almost all the way through with the hammer coming down directly over the edge. When you're almost all of the way through, shear off the last little bit with the hammer off-center, so that it goes off to the side.

[M.G.]

Thanks! I'll keep it in mind.

[ThomasPowers]

I don't teach that to new students as they generally manage to flip the cut off piece. I have them stop close to being through and bend it off with another pair of tongs. I have seen a cutoff travel over 20' before.  Great excitement in a crowd!  Learning how to feather their blows seems to be an advanced skill for some students; perhaps because they were not willing to hit the workpiece on the hardy a good blow to get started and had to be encouraged then and discouraged towards the completion of the cut.

[M.G.]

Yeah, I can see that being an issue. Ive seen the bend break to finish cuts as well. All great tips for using my new tool. Im not gonna light the forge today to get the HT done, being a charcoal opperation, ill wait till I'm going to be running my next project and do it at the start of my day. Im thinking of trying to forge a cork screw tomorrow.

[Heelerau]

Neat job of the cutoff,  I normally cut almost through, then put the piece  cut on the edge of the anvil and strike  off  the waste with the hammer. 

[M.G.]

Thanks. Ill be giving all these methods a go at some point or another. I think ive decided I need to make a top tool hot cut this next week as well. So im sure I'll be looking to you guys for top tool cutting, tips and tricks. Some time in the near future. 

[ThomasPowers]

For top tool cutters I like the high alloy steels, my favorites are S series (I've used S-1 and S-7) and H-13 as they stay hard even when buried in glowing metal.

[M.G.]

Ok, got back into the shop today. Groun, heat treat, and put an edge on the hot cut this morning. Then spent all day attempting to make a corkscrew from some coil spring. I failed,  the tenon to become the screw of the corkscrew kept cracking on me, I may have burned it at some point in forging, or I worked it too cold. It heats up and cools off pretty quickly that small of a taper. But the good news is I got plenty of practice using my new hot cut hardie tool, removing the wasted cracked and burnt portion of said project.  Here are the final pics of the hot cut.

[Frazer]

Mark Aspery has a great video on how to make a corkscrew. Granted his isn't using a tenon, but the approach will probably be similar.

This is my rendition of what he made.

I used spring steel and a mandrel to wrap (not what he shows), then a chisel to open up the coil. The spring I was using would harden if I closed the vice on the tip above critical temp, then it would snap off, so I know your frustration. Corkscrews can be very fiddly.. I had to make 50 of them for a winery and it took much longer than I expected.. Good luck, you'll get them nailed down.

Btw I like that hot cut, very nice indeed, Way better than the one I made.

[M.G.]

Yeah thats the one I was trying to make, sorry I misspoke not a tenon, the step-down and drawn out portion that becomes the screw, thats where the cracks were showing up during the draw out. Yours look quite effective. I think ill need to work on my pre form a little bit too. But maybe after a couple more ill have it figured out. 

here is my first attempt,I quit after I noticed a crack forming about mid way down the screw bit. And that was after cutting off about an inch and a half incrementally from the tip, due to cracking.

[Frazer]

For that isolation I use a rounding hammer and the horn, my best suggestion is to leave everything a little longer and a little thicker than he says. I didn't really follow his measurements exactly. I forged a long square (IIRC he used 3/8? I would have to check my book for all the measurements he used and what I ended up going with) isolated the amount of material I would need for the corkscrew (plus an inch or so), thought about how long I wanted the handle to be, multiplied that by 2 and added a bit to compensate for the bend, forged that round, made the hole, (remember that hole is supposed to be bigger than the diameter you isolated for the screw, but a little smaller than the length you'll fold over into half of the handle handle, so when you feed it through it stops where you want it to) then you can cut off the other end to the desired length.

I will say having a pair of box jaw tongs that can hold both the handle side(s) and the center is super helpful for that whole fiddly process once it's cut from the main piece. (picture is from the split RR spike corkscrews I made a bunch of, but I use those tongs for both).

My first 2-3 went from the forge to the anvil to the "this attempt didn't go as I planned, but maybe can be repurposed later" bucket (which always seems to fill and never empties...) and they're probably still there today... Anyway you'll get them, they are a pain in the butt on the first few go's. At least they were for me. 

I didn't have any trouble with splitting. It is possible that particular spring has some stress fractures that are giving you trouble or maybe it's an alloy that is more particular about it's working temperatures. I've come across springs that I couldn't stop from air hardening for the life of me and others that never got as hard as I had expected them to. We say spring steel as a general term, but there are a lot off different eggs we throw into that basket.

[M.G.]

Thanks for the tips. Box jaw tongs are on my build list for the next couple weeks.

[wirerabbit]

Nice looking hardy, MG. So how do you like your charcoal forge these days? I liked seeing how your forge design changed as you got more information. I'm really interested in knowing how the cutouts for a lower hearth seem to be working out for you. My similar forge has the tuyere lower from the hearth than yours seems to. Was wondering if you fight the charcoal to keep it in your firepot.

Would you mind telling me the full firepot dimensions including the level of tuyere? You seem to have more room in there for those monster jackhammer bits you have been forging into tools!

I get pretty hot temps in mine without having to top with firebricks. Can easily spark carbon steel if I'm not careful. Have not yet tried to forge weld anything at this time.

Rock on.

[ThomasPowers]

Making a smooth rounded transition helps prevent cracking.  I use a swing arm fuller with rounded edges to establish the transition and then hammer the one side down smaller, just like I do for tangs on knives. (Though a corkscrew will use a smaller fuller than the knife tang generally will!)

[M.G.]

Thomas, the cracks were developing mid way down the isolation for the screw, and at the tip when I would try to give it a fine taper point. I think I may have had pre existing cracks in the material. Or. I burnt it at one point then later likely hammered at too low of heat. 

Or all of the above.

[ThomasPowers]

All of the above can be a real issue getting into the craft; one of the reason's I try to get new students to work with real mild steel for their first projects. (Not even A-36!)

Remember how to get to Carnegie Hall?

[M.G.]

This morning I woke up thinking I should have just attempted a corkscrew from mild steel,  especially if I was just gonna throw it away. 

For sure there is lots of practice in my future.

 

[Frazer]

One thing for the mild steel corkscrew, you have to leave the screw part noticeably thicker. They chew up the cork more going in, but at least they don't bend while you're screwing them in.. once they bend (partially unwrap themselves, however you want to think of it) you're pretty much hooped. If you straighten it back out, by the time you rewrap it it's even thinner and it's bound to happen again. At least in my experience.

If they're going to be for decorative purposes then go with what looks best. 

[M.G.]

Wirerabbit, thanks! 

But in attempt not to muddy the waters in the hot cut thread, I will post a thorough reply in my forge build thread and tag you in it, we can pick up this discussion over there.

 

Frazer, as for using mild, I would only be doing that as practice, to work out my preform proportion and technique without wasting time and energy on carbon steel just to toss it in the scrap bin. I figured that mild would not be suitable for actually extracting corks.

[Frosty]

Try calling the local welding supply and ask for a medium carbon Tig rod around 1/16" - 3/32" diameter. It's available in a bewildering range of alloys that makes my head spin. I was going to link a chart but all the links are commercial sites and are loaded with info you just don't need. All you want it reasonably thin medium carbon wire you can forge into a cork screw.

This is something to ask the guys at the counter, they have the books and know where to look without having to wade through ads. Don't get into what you're doing, just ask for 1/16" tig rod in a medium carbon steel, preferable forgeable. Tell them you NEED food grade! They'll probably suggest a Stainless but as long as it doesn't contain a toxic metal a non-stainless steel is fine, you can season it like a skillet.

Buy a couple sticks, you don't want a lb. or five any regular welding supply keeps opened tubes of various rods out for folk who just want a stick or two. It's more expensive per unit but a tube of rods is spendy. IIRC we're talking $2-3 / stick or $100+ per lb. difference. 

Cut short lengths, say 1" or so for test coupons to get the heat treat right. We'll walk you through it.

It ain't cheap but you can produce a quality cork screws with a reasonable expectation of success. Yes?

Frosty The Lucky.