stupid question about using diamond chisels

[Alaisiagae]

So, I tried using my diamond chisels on some thin (2-3oz) veg tan. I am making a pouch with 2 pieces, so I lined up the front and back piece, rough side touching rouch side (grain/grain facing out) and used the chisel to punch through both from the grain side of one piece through and out the back of the grain side of the other piece. Aside from make a total disaster out of it (diamonds are angled all wrong, my bad), the holes out the back piece look bad: the leather on the grain side got distorted and wrinkled around the holes. What am I doing incorrectly? I feel like I keep making rookie mistakes, is there a big list of "never do the following things"?

[Aven]

Did you glue the seam together first?  It doesn't have to be uber strong, just keep the leather from shifting around while you punch your holes.  How large are your chisels?  What were you using as a backer while punching? 

Pictures help.

[Alaisiagae]

1 hour ago, Aven said:

Did you glue the seam together first?  It doesn't have to be uber strong, just keep the leather from shifting around while you punch your holes.  How large are your chisels?  What were you using as a backer while punching? 

Pictures help.

I used double sided tape ("Tanner's Bond") along the edges to secure the two pieces. I punched on top of a poly cutting board. My chisels are these ones  (diamond hole chisel set) from Tandy. I dyed after punching, not before.

Edited August 29, 2020 by Alaisiagae

[Aven]

I'm not familiar with Tanner's Bond.

Are the small marks where you expected the chisels to come through on the back?  I'm assuming you are showing the back piece.

[Leather20]

When using diamond punches it helps to first mark your line where you're punching and then line up your punch with one prong in the hole you perviously punched. Also, how are you removing your punch? Sometimes the way you remove the punch affects your holes.

[fredk]

Are the teeth really sharp? Those holes suggest they are not. Sharpen them and polish the teeth up, both the cutting end and the sides. Also press into wax before every, or every other, strike. It becomes a rhythm; into wax, punch holes, punch holes, into wax, punch holes, punch holes, into wax. . . . . 

Mark your line on front and back. After the first set of holes check that they are coming out on the line. If not adjust how you hold the chisel. Use the side of your hand to press the leather down and the fingers of that hand to guide the chisel. Hold the chisel lightly, just enough to keep it upright.

[Alaisiagae]

31 minutes ago, Aven said:

I'm not familiar with Tanner's Bond.

Are the small marks where you expected the chisels to come through on the back?  I'm assuming you are showing the back piece.

Yes, that's the back piece. It's medium strength tape, it can be removed and isn't a permanent or super strong bond.

31 minutes ago, Leather20 said:

When using diamond punches it helps to first mark your line where you're punching and then line up your punch with one prong in the hole you perviously punched. Also, how are you removing your punch? Sometimes the way you remove the punch affects your holes.

Yes, I had some trouble negotiating the curves... it's easy when it's a straight line! I did put one of the prongs in the previous hole,  but as you can see I erred when turning the corner and flipped the chisel so the slant changed. I tried to pull out straight up-and-down, but it's possible I yanked at an angle. I poked the chisel in beeswax to help ease pulling the chisel out. 

1 minute ago, fredk said:

Are the teeth really sharp? Those holes suggest they are not. Sharpen them and polish the teeth up, both the cutting end and the sides. Also press into wax before every, or every other, strike. It becomes a rhythm; into wax, punch holes, punch holes, into wax, punch holes, punch holes, into wax. . . . . 

Mark your line on front and back. After the first set of holes check that they are coming out on the line. If not adjust how you hold the chisel. Use the side of your hand to press the leather down and the fingers of that hand to guide the chisel. Hold the chisel lightly, just enough to keep it upright.

The teeth are electro plated, so to sharpen them I'd end up scraping that off... I'm a little reluctant to do that. 

[GatoGordo]

First of all, you did not err by flipping the chisel when turning the corner. Actually, you can't. Prove it to yourself by holding your chisel, punch a set of holes, rotate the chisel by 180°, and then punch another set next to the first set. They will look the same. On you piece the holes go from upper right to lower left or //// as seen from the front. This occurs all around your piece and is easily seen if you look at the holes while rotating the leather to keep the edge on top.

My guess is that the problem you do see comes from two sources. The tape has some thickness and allows the thin leather surfaces to move a bit with regard to each other. The holes look odd on the back side because you are cutting directly on a poly mat. This does not allow the chisel to penetrate very far past the leather and since the tips of the prongs are sharpened if they penetrate to different depths, they result in holes of different sizes.

I suggest you try gluing the two pieces together and then place a sacrificial piece of leather between your work and the poly mat. This will allow the prongs to penetrate beyond the sharpened tips to give a more uniform hole.

[Frodo]

18 minutes ago, GatoGordo said:

First of all, you did not err by flipping the chisel when turning the corner. Actually, you can't. Prove it to yourself by holding your chisel, punch a set of holes, rotate the chisel by 180°, and then punch another set next to the first set. They will look the same. On you piece the holes go from upper right to lower left or //// as seen from the front. This occurs all around your piece and is easily seen if you look at the holes while rotating the leather to keep the edge on top.

My guess is that the problem you do see comes from two sources. The tape has some thickness and allows the thin leather surfaces to move a bit with regard to each other. The holes look odd on the back side because you are cutting directly on a poly mat. This does not allow the chisel to penetrate very far past the leather and since the tips of the prongs are sharpened if they penetrate to different depths, they result in holes of different sizes.

I suggest you try gluing the two pieces together and then place a sacrificial piece of leather between your work and the poly mat. This will allow the prongs to penetrate beyond the sharpened tips to give a more uniform hole.

Gatogordo hit the nail on da head

place a piece of thick leather under your work,  a ploy board is for cutting on

my pounding leather strip

[Frodo]