The first night that I was at Tom Clark's school he showed me a video of Alfred Habermann and Uri Hofi along with a few other smiths slitting and drifting a 4" hole in a 4" piece of round stock.

For a 4 inch hole do you want the slit to be pi times diameter long (approx. 12 inches)?

You mean 6'' slit long half of pi x d no! I made the length of the slit 5.11''
means 130 mm because i wanted to get a nice hole all around. I went in with three gradualy growing drifts the last one was the same size of the cross beam and then after i heated the ''eye'' and pushed it in the ''eye'' shrinked on and hold the construction together.
I use a lot this shrink calculation in many places in furnituer or other places that i want a good hold with out welding or rivetting .one of the coffy tables that i produce a lot (and i wan the first prize in a disigen competition in jerusalem netional museume) of the is based on the shrink hold and many tools too.
Hofi
hofi

Your right I meant 6 inches, just writing quickly on breaks from the forge. I was wondering what the stretch from a drift would be? Is that info in one of the BPs? Thanks

Archiphile, here is another way that I slit and drift thin stock. I can do 3/16", but you can not drive your punch to deep where it spreds the material out too much, so it's a little bit trickier to do 3/16th. If you drive your punch too far when you go to punch the plug out from the other side and hit the anvil, you will cause the plug to swell, and it will be harder to pop out clean. If you line up your punch perfectly, it will come out perfectly. If you don't, it will still come out because it seeks the path of least resistance, but it won't come out perfectly; there will be burrs. The drifts are made like Uri Hofi makes them where they are tapered in one direction and the width of your hole in the other direction.[This is a major improvement over traditional drifts that are just tapered round because with a round taper you get a shoulder from the smaller size of the drift at its starting point before you reach its finish point.]

Alwin the calculation of the shrink /expansion is acc to the BP
the length of the slit no. on big od steel the calculation differs acc to what you want to achive
Archipile on thin matirial to make sure you get a clean cut after the first hit open the vice a bit gigger then the slitter and finish there the pice will fall dowen in the openning
Hofi

Alwin the calculation of the shrink /expansion is acc to the BP
the length of the slit no. on big od steel the calculation differs acc to what you want to achive
Archipile on thin matirial to make sure you get a clean cut after the first hit open the vice a bit gigger then the slitter and finish there the pice will fall dowen in the openning
Hofi

Yes. you could do that, but I was talking about doing it all on your anvil where it can be done. If you didn't do it perfectly, it is better to take it to a piece of wood and pop the plug out.

If one ensist to do it on the anvil the easyest way is to ''GO'' with the slitter fast as deep as you can and get a very thin layer dowen on the anvil face hit it a bit more but very easy only to cool the bottom until it is darken then turn over and put the slitter on the darken mark but tilt the sliter a bit and hit then the corner will start to cut and the slitter will shear it like scissors.

Gerald,

That's a very nice touch. Thanks for posting the pic.

Gerald, those little details add so much to the finished product. Is it on a table you've made?

I'm not sure if my last pictures were clear enough. Can you all see the grind on those slitting punches? I've never seen anyone grind punches like that before for thin stock. That's one of the things I wish I knew from the start.

I can't see what the grind is on those Brian.

I'll take some more pictures. If you look at the plugs that came out and the holes that I didn't punch out you can see the impression the punch made and that is the negative of the grind. I'm doing this for the Blueprints that Archiphile suggested. Thanks for your response, Alwin.

Like what has been said before, this is a very good thread.
Brian
Will we be-able to see the BP or will it be one that we get to see when all the BP's come back online.
I've been trying to make some tools but am having trouble but this thread is helping.
Looking forward for the BP

Gerald, I really liked what you called "wordy" in your above post. Keep those words coming! Also great pictures!

I'll take some more pictures of those punches so you can see the grind. What the grind allows me to do is hundreds of holes without redressing my punches, unlike a flat bottom punch that will require dressing as soon as it gets mushroomed.
Here are some other pics I took yesterday of the same principal. Let me know if it is clear. I intentionally included some mistakes that are marked with an X, so you can see what can go wrong. The handled slitting punch is ground for thicker stock and you can see how it touched the anvil and flattened its point.

I can see that the pictures don't show all the details now. Sorry! I'll get back out there and take some more.

Okay, here's some better pictures of the slot punches that I use for thin stock. The second picture shows what happens when you drive your punch a little too far from the first side. The longer slot also shows what happens when your punch is not lined up. Notice the ledge on one end and the burr on the other end. The plugs still come out but not as cleanly. The next picture shows a better hole and the impression and depth that I drive the punch. The last picture shows the bad holes and the finished bottle opener made from the piece in the third picture. These punches get used alot and they rarely need redressing. The plug protects them from hitting the anvil and you don't need to punch out over a hole or in the vice where you could possibly hit it on an edge. These punches were made from 4140 because that's what I had at the time.

Very nice, thank you. I'll be trying that soon.

Thank you all, also. This sight is helping me too. I've never really taken the time to document this stuff before now. I'm looking forward to going to Virginia. I've never been to that part of the country. We'll see you there.

Brian you almost have a tutorial made when you show the pictures, or a BP Hmmmmm I wunder!

I have to say that when I posed the question here I did not realize that it would garner this much attention. Nor did I realize that it was also and issue of such hot debate. Thank you all for your gracious replies.

"On occasions the end of the punch is so damaged by this, that it swills and cannot be removed from the workpiece"

I did that the other day.:p

This thread just keeps getting better.
Gerald,
The book you were talking about sounds very good. I did a search but couldn't find it. Where can a copy be purchased if you don't mind me asking.
Thanks
Billy

thanks Gerald

Thank you, I'll try to put it all together. Should I cover punching in general because there is quite a bit more, or should I do something more specific like the slitting and drifting? How should I send it?

YES PLEASE!!!
I would love to see a detailed blueprint for how to make your own slitters and drifts (round and square). A Video would be even better but I'll be thrilled with anything that explains the whole tool building process. Step bt step instructions on how to USE the tools properly would be wonderful as well. Thank you so much Archipile for volunteering to do this.
SWEET!
Sam