How Do You Make Perfectly Round Corners?

[Dwight]

Take a piece of 3/4 inch EMT (that's thinwall electical metallic tubing, . . . pipe) about 8 inches long.

Take it to a sander and very carefully roll it around against the sander (keep dipping it in water to keep it cool) until you have a fairly sharp edge made on the inside circumference of the pipe. You should have a long, slow taper to the sharp edge. When you are done it should look like figure 1.

Next, . . . place it in a vise, . . . sharpened end straight up, . . . and cut directly across the full diameter with a hack saw. Make this cut about the depth of the width of the hacksaw blade.

Decide which of the two halves has the better looking edge, . . . cut the other half off at about the depth of the width of the hacksaw blade. Looks like figure 2.

Now comes the fun, . . . you have 180 degrees or a half circle of cutting edge left over. (This makes a wonderful punch for round ends for straps, etc, . . . so you may want to make another one.) I digress, ................... NOW, . . . very gently and very carefully measure and mark off 3/8" on each side where you will cut the pipe twice, once on each side. These cuts will give you a couple of wings on your 90 degree corner cutter. Fold out the wings so they look like figure 3, but also have the basic shape of the little circle (unlabeled figure 4) above figure 3.

Lay those wings against the leather corner on the outside at a slight angle, . . . rock it back, . . . mallet the rascal, . . . perfectly formed corner, . . . every time.

May God bless,

Dwight

cornercutter.bmp

[joobacca]

I think Bob Beard of ProSeries Tools makes them in sizes.

I'm not so sure about shaping a round punch.

A corner cutter would need to straighten out at the edges of the corner.

I've used my swivel knife for this kind of thing before.

Just follow up your cut with you clicker knife and clean it up with a rasp or sand paper.

Thanks! Just sent him an e-mail!

Take a piece of 3/4 inch EMT (that's thinwall electical metallic tubing, . . . pipe) about 8 inches long.

Take it to a sander and very carefully roll it around against the sander (keep dipping it in water to keep it cool) until you have a fairly sharp edge made on the inside circumference of the pipe. You should have a long, slow taper to the sharp edge. When you are done it should look like figure 1.

Next, . . . place it in a vise, . . . sharpened end straight up, . . . and cut directly across the full diameter with a hack saw. Make this cut about the depth of the width of the hacksaw blade.

Decide which of the two halves has the better looking edge, . . . cut the other half off at about the depth of the width of the hacksaw blade. Looks like figure 2.

Now comes the fun, . . . you have 180 degrees or a half circle of cutting edge left over. (This makes a wonderful punch for round ends for straps, etc, . . . so you may want to make another one.) I digress, ................... NOW, . . . very gently and very carefully measure and mark off 3/8" on each side where you will cut the pipe twice, once on each side. These cuts will give you a couple of wings on your 90 degree corner cutter. Fold out the wings so they look like figure 3, but also have the basic shape of the little circle (unlabeled figure 4) above figure 3.

Lay those wings against the leather corner on the outside at a slight angle, . . . rock it back, . . . mallet the rascal, . . . perfectly formed corner, . . . every time.

May God bless,

Dwight

Thanks for the detailed explanation Dwight! I wish I were more of a handy man. If I were, I'd definitely try my hand at this, but alas, I am not!

Jason

[joobacca]

Thanks for all your help folks! I will definitely give the metal washer a try. I haven't had any trouble cutting the leather, it's just that when I fold the piece of leather together, the corners don't always match up evenly. I thought if I used a punch, it would keep things a bit more consistent!

Thanks again,

Jason

[DaveT]

Here's a couple ideas. Mark your corners like you've been doing, anything round will work as a template. You can use a knife (Any kind) to cut the corner at a 45 degree angle to nip off the extra material. Now repeat a couple times until you are really close to the curved line. Once you have all the corners nipped off, fold your card case so the opposite corners match up. (Do all this BEFORE laying out your stitching lines!) If you don't want to tap the fold lines flat with a hammer (I use a polished smooth faced ball peen hammer) clamp the edges in line with clothes pins, binder clips, or small plastic spring clamps. Cover the clamp jaws with some masking tape if you're worried about leaving marks. Now use a rotary tool (Dremel) with a sanding drum or a small belt sander to sand the corners to the marked line. This way all the layers of the leather match up and are sanded to the same shape.

Finally, to make your own half round and quarter round punches, I buy a cheap set of hardware store hole punches. (http://www.harborfreight.com/9-piece-hollow-punch-set-3838.html) Using a grinder or dremel with cut off wheels, remove half or three quarters of the punch. For larger sizes, use a hole saw that you grind the teeth off of, then grind the edge to sharpen it. Remember to keep the steel cool by frequently dipping in water. Keep your fingers near the area you're grinding, if it's not too hot for your fingers, it's not hot enough to ruin the steel.

Hope this helps

Dave T.

[leatherkind]

. . . rock it back, . . . mallet the rascal, . . . perfectly formed corner, . . . every time.

Thank you Dwight for your suggestion.

I was looking for something that would allow me to make repeatable and high quality cut.

Followed your instructions I was able to make a 75 mm diameter (3 inch) corner rounding punch.

http://leatherworker.net/forum/index.php?showtopic=7801&view=findpost&p=216263

It works very good.

[FlHobbyist]

I've done a fairly through google search and it looks like the answer is still two options:

1) Buy metal working equipment, learn how to use it and make your own quarter round punch.

2) Put in an order with Bob Beard and with a little luck you should have it in a year or so.

There is another pair of observations for doing quarter rounded things that weren't mentioned here:

External corners: Draw corner on leather and use good scissors to make the cut. Scissors are a lot easier to control than a razor knife. Admittedly this method won't work with thick leather. What is thick leather? For me the answer is 8 or 9 oz is going to be about it with my pair of scissors. This trick was in one of the Hurst videos.

Internal Corners: Draw lines of where the corner will ideally be, then carefully align circular punch on top of lines and punch out the corner. This trick was in one of the Stohlman books.

I believe if someone with a little metal working skill wanted to make some money, this would be a good place to start.

[Northmount]

Can also use wood carving tools ... sweep, gouge, etc. available in various curves.

Tom

[FlHobbyist]

Can also use wood carving tools ... sweep, gouge, etc. available in various curves.

Tom

Thank you for the clue. Just eyeballing it, it looks like a #8 sweep gouge is what one needs. I'll be ordering a #7 and a #8 this afternoon, and I'll post back my luck either good or bad.

[FlHobbyist]

Doing some more searching on ebay, it looks like at least 1 shop in China might be making these punches. They're calling them "English Semi Point" though one has to be careful as it looks like "English Semi Point" may mean other things to other Chinese entrepreneurs. In any event here is a link to a current auction offering them. Late next month I'll add to this thread with what they sent.

http://www.ebay.com/...984.m1497.l2649

Edited August 30, 2013 by FlHobbyist

[Trevor]

My two cents worth. Get yourself an electric drill and a vice to secure it in. Next get a round disk sanding abor from your local hardware store. Also get some fine sandpaper disks and some rougher ones and put the paper into the abor. With the whole thing mounted in the vice securely turn on the drill and lock the switch, then with the curve drawn on the leather and a basic cut done first to remove the bulk of the edge, sand the edge until the leather is perfectly round and smooth. You will find that its easier with heavier leather. Also heaps of dust. but you will end up with a very nice corner after some practice. Hint: Get an old vacuum cleaner from the op shop and mount the hose next to the disk to collect the dust. Use the heavy grit for big jobs and the fine for anything delicate. Cheers TK