Hot Slitting Clean Up

[dognose]

Need help figuring out the best way to clean up the inside of a slit bar. The chisel leaves a V shape cut that is proving difficult to remove. I tried building a "bridge" tool, also tried opening the slit into a squashed football shape and filing it, neither of which provided the results I was hoping for. Thought I might see if anybody had any tricks I could try tomorrow. Thanks

[jeremy k]

From your picture - now re-heat and hammer gently back to Square - this helps force the "V" from the cut back into itself so when you open it up afterward, there is less "V" if any on the inside. Also it helps true everything up so when you do whatever to it afterward you can control it better.
This corrects the deformed part ("V") and helps place the metal back were it should be but with a slit in it.

[Charles R. Stevens]

Next time use a slitting punch instead of a chisel. You'll get a much cleaner opening to work with. What kind of finished opening are you trying for?

[dognose]

I did try that although perhaps the stock I was using was too thin as it seemed to just fold in on itself before forging the V out. Will try it again with thicker stock and see how it goes. Any other methods anyone can think of?

[dognose]

Next time use a slitting punch instead of a chisel. You'll get a much cleaner opening to work with. What kind of finished opening are you trying for?

I'd like the bar to end up with only a small parallel gap running the length of it, square up corners.  

[Charles R. Stevens]

Ok, so what you want is a long mortis in the bar? If you use a punch instead of a chisel, flat bottomed with all the edges slightly chamfered and a slight rock, or a very blunt point to the business end on the long axis it will give you a better form to start with, then drift to final shape. I know it's counter intuitive.

[brianbrazealblacksmith]

Dognose, I started a thread back in 2009 called "Somthing new to me", and it talks about the very thing you're asking about. The pictures I posted don't show up anymore, but if you slit and drift two holes a distance apart then chisel the distance between the two holes, you can twist the two sides, one at a time with one side held in a vice, 180degrees and the flat sides will now be in the middle making it easy to line up your slot or open it up. The thread is on page 100 of General Discussion.

[JNewman]

Lots of good advise here.  With any of them it is a good idea to either upset the area being slit before slitting so you have a little extra material or start with heavier stock and draw down either side of the slit.   

 

When doing a long slit I have found it easier to slit only from one side into a scrap piece of mild steel rather than trying to slit form both sides,  you end up with the burr on the outside this way where it is easier to file and or grind than in the middle and it is a much cleaner burr.  You can then offset the 2 sides to forge the sharp corner into the bar.  of course this will draw the bar out somewhat but that is why you need to upset first.  I  have done eyebolts this way where it was critical there not be any cold shuts where the 2 slits meet as they would show up as cracks in NDT. testing.

 

Another way probably easier way to go about this is to forgeweld 2 bars together on the ends then forgeweld your flatbars on the ends   All the ends would need a little upsetting to compensate for the drawing out while welding. 

[rockstar.esq]

To salvage your work you could use a cape chisel the slot width and cut using a leg vice as a guide with the work held vertically.  I've also seen a broach in an old blacksmithing book that looked like a drift with staircase / terrace cuts on the leading edges to cut a particular profile.

[dognose]

Dognose, I started a thread back in 2009 called "Somthing new to me", and it talks about the very thing you're asking about. The pictures I posted don't show up anymore, but if you slit and drift two holes a distance apart then chisel the distance between the two holes, you can twist the two sides, one at a time with one side held in a vice, 180degrees and the flat sides will now be in the middle making it easy to line up your slot or open it up. The thread is on page 100 of General Discussion.

Found your thread, too bad the pics are gone because my feeble brain can't seem to get a grasp on picturing the method you describe. What does slitting and drifting the two holes accomplish? Do they prevent future cold shuts and do they show up in the finished piece? I'll attach a poor quality photo of an old iron cross I'm trying to duplicate, and the slit portion of the piece is the one that's holding me up. If it helps or matters, the finished cross is about 32" in diameter. Thanks for all the advice so far. 

[Rich Hale]

Now with a pic...I would open the holes up,,,clean the ends up with files and abrasives,,,include the full length of each surface of the slit then bring them back parallel. A correct thickness steel item in between would help and likely could be done cold if mild steel.

[brianbrazealblacksmith]

Dognose, my wife, Karen, posted some pictures that I took yesterday to show what I was trying to explain. They are posted in the thread above, Something new to me. After seeing your picture thou, it is not what you were after, but it is worthwhile information anyway.

[dognose]

i saw that today and tried sending you a pm, think it may have went to the wrong person. will try and sort it out. thanks so much. very useful info.