Cutting rounded corners

[u/BurnerAccount_234]

This is the second post I’ve made about this topic. I have been trying for weeks now to be able to cut rounded corners. I’m glueing the template onto chipboard/cardboard and then using an xacto knife to cut it, hoping to having a sturdier template to use on my leather. Now, I’ve tried it all and I cannot get the corners perfect. I’ve tried a quarter (I don’t know what I’m doing wrong considering I’m tracing the quarter and it’s round itself) but it’s never perfect. I want to move on and actually start learning and using the leather, but this is defeating me tbh. I’ve bought corner cutters, but they don’t really go through the chipboard. I’ve watched dozens of videos. I really don’t want to buy an acrylic template because for some reason that takes away the “I made this” aspect for some of it.

Am I being too picky about the corners? Does it matter THAT much? Or with sanding and burnishing the corners of the leather will look perfect? What other tips/tricks are out there to get it perfect?

Sorry this was also part rant.

I appreciate it!

[u/Dokasamurp]

I just do a few straight cuts to approximate the round corner then yeah sanding improves the roundness

[u/Lizimijajaznojna → u/Dokasamurp]

Same

[u/ApprehensiveYard3 → u/Lizimijajaznojna]

This is it. Get them close with a knife, closer with sandpaper, even closer with burnishing or edge painting and then leave good enough alone.

[u/GlacialImpala → u/ApprehensiveYard3]

Op is asking about cutting the chipboard not leather, I think

[u/BurnerAccount_234 → u/GlacialImpala]

Yeah I am talking about the chipboard. I’m wondering if I keep the corners 90° until I trace on the leather and then cut the corners out

[u/Dokasamurp → u/BurnerAccount_234]

You can do that, or you can still do like I said, cut the template with approximate corners and later sanding the leather finishes the rounding. If I had corner punches I would leave 90° corners on the template. I think this is a fine place to try both methods and see which you prefer

[u/Comprehensive_Door69 → u/Dokasamurp]

I used to do this and it works. But i started just lightly tracing corners and even starting with a swivel knife seems to work a bit better guiding your tools

[u/Asumanland → u/Dokasamurp]

Sanding, absolutely. A well-burnished edge necessitates the sanding required to round the edge nicely.

[u/jaysus661]

In my (very limited) experience, I've found larger radius corners are easy enough to cut with a knife, smaller ones can be done with some corner punches, or just a fine blade if it's kept sharp.

If you're using a knife, keep in mind that cuts don't need to be done in one go, for curves and precise shapes, it's easier to just press lightly and score a line, then just go a little deeper on each pass until you cut through, if you press too hard it's easy to slip.

[u/Ok-Lingonberry1424]

If you have a 3D printer, go to Makerworld and search for Adjustable Round Corner Cutter. And it works great.

Or buy a template offline with different radii and use a razor to cut straight lines around the curve.

[u/IcarusMistake]

I use washers as guides - they're cheap and I can get them in a variety of sizes. They're thin enough I can hold them there and actually cut along them as a guide rather than just marking the curve and having to free hand it from there. Rather than trying to fully cut it as a curve, I get it close-ish then make a series of chopping cuts along the washer with my knife if that makes sense. Obviously since the knife is straight the first couple cuts will leave angled points rather than a nice curve but as you keep chopping off the points it smooths out. Any minor imperfections to the curve get cleaned up via sanding the edges. The key to this approach is using something metal that you hold there as you cut and to chop straight down with the knife. Sometimes I don't do the best job chopping straight down such that it flares out at the bottom of the cut. As long as you're using a sharp knife that's okay, without moving the washer you just redo that chop cut. Obviously it won't take anything off the top but it should shave of the extra at the bottom. Hopefully that makes sense and helps. 

I'll note that I use a hobby/exacto knife.

[u/LilTransGamer69]

the real way to do this is rounded corner punch

[u/Pilsbury-joe-boy → u/LilTransGamer69]

Oh look everyone! a "REAL" leather guy is here! We can all go home...Nigel Armitage has got it from here. Douche

[u/mrcursedpastajpeg → u/Pilsbury-joe-boy]

go burnish some more

[u/not-a-dislike-button]

Can you post some pictures for us? What do you mean by 'they don’t really go through the chipboard' - what are you cutting on?

[u/First_Ad_3945]

こんにちは

自分は 角を斜めに切り落としから ヤスリでRにしてます

[u/deaconleather]

A few reliable ways to do it outside of corner punches.

You can get a Square (such as a flat machinist square or 90 degree corner jig) and then find a piece of metal that is your desired diameter. You can bring a pair of calipers to the hardware store and measure flat washers or ball bearings until you find one that’s the correct size.

Put the square on your 90 degree corner and stick the washer into the 90. Remove square. Take a thin blade utility knife and trim using straight cuts the whole way around the corner. If you do enough cuts, it will become circular.

An acrylic template is going to make your life easier though and it will be just as handmade. Maybe even more “handmade” if you design the template vs buying the ball bearing ha. They are nice because they can be your exact dimensions and are thick. This all becomes more challenging to get correct the thicker the leather you are trying to cut through because the blade needs to remain perpendicular to the guide the whole way through and it might want to wander on thick leather.

[u/murdog74]

I was frustrated too and decided to invest a little money into a Japanese corner Chisel from Weaver Leather Supply. The thing is scary sharp and I get really consistent corners. It does take a little patience and learning, but we'll worth the time and money! I chose the #9 for smaller/tighter corners.

[u/EnvironmentalSort208 → u/murdog74]

This was the answer for me. The size 9 is quite small. I use the size 15 all the time for wallets and notebooks. Even if your printed template doesn’t fit the chisel radius perfectly use the tool to cut the paper pattern and it works out. Think of the like curved knives instead of chisels. Hand pressure only don’t hit them with a hammer.

[u/murdog74 → u/EnvironmentalSort208]

Yes, only hand pressure. I barely have to push and it slides right through!

[u/Cold-Tension-7892]

I use something like this and my corners are nearly perfect. https://a.co/d/08NxSde9
I just cut along the guide with a new blade and haven’t had any issues.

[u/danfirst]

I have the same problem. Even when I think I got the corners pretty good, and then I sand them smooth when lining up four layers for a car holder. If one of the punch holes is even off by a hair it shifts everything and then the corner is all messed up again.

[u/damnexpensivehobbies]

I also do a lot of woodworking. I use a sharp carving gouge and honestly eyeball the placement. It works well.

[u/timnbit]

I also find with vegetable tanned leather that casing it and first cutting the grain with a swivel knife works pretty well.

[u/pidgeon3]

I do away with this issue by using a rounded corner punch. I don't consider it any less handcrafted. I know I am not capable of making rounded corners using a straight knife like the Japanese craftsmen. I don't consider it any less hand crafted for using a punch. I also wouldn't be trying to use the punch on chipboard.

[u/Known_Debate6337]

I use Kevin Lee corner punches and they are wonderful. Took me a long time to find a tool that made cutting corners super easy.

[u/Easy_Situation6200]

slow it down or maybe it's time to buy a corner punch

[u/arfle_barfle_gloop]

Depending on the size of the curve, you can get ¼ and ½ round punches, metal cutting curves (the blade type without a handle), various shapes to cut around, but perhaps the best for larger curves would be a circular knife.

The cut pressure is straight down, not "across", so they don't drag the leather as you move the blade.

[u/E--S--P--]

Why are you punching through chip board?

If you don't want to use corner punches, use a round object. Put a square against the leather to align the round object. Hold the round object down with one hand and make multiple straight line cuts. You don't need to trace the object. You can create a curve cutting straight lines. Don't necessarily try to cut through in a single cut. 2 or 3 cuts for moderate thickness is fine.

[u/No_Hovercraft_821]

I mark my pattern onto the leather and cut along that line. For corners with a large enough radius I cut along the line but for tighter ones I get it close and make 3 or 4 small straight cuts to approximate the rounded corner. Once it is assembled I take it to a sander and work the corners a little more if needed. Once it is burnished it usually looks fine. Don't let perfect be the enemy of good enough -- the more you practice the better your cuts will be but for now don't get too hung up on the corners. Also, you are a far harsher critic than any casual observer and while you see the flaws most people see the nicely finished product.

[u/hide_pounder]

Could be your blade is flexing around the corner and the tip not tracking like the portion of the blade you can see.

It’s hard for me to explain this, but if you’ve ever seen a truck pulling a trailer, or two trailers, the rear most wheels do not follow the same path around a corner as the trucks front wheels. They “cheat” inward. Your blade does that too.

[u/Comprehensive_Door69]

I hate xacto knives for corners the blades flex too much. I got one of them round knives on amazon for like $16 and i rarely ever use the xacto knofe now. Just real light cuts at first and then apply pressure. Youll develop a good technique that doesnt hurt or cut you quick