Sometimes pretrimming points
helps to make blocks accurately.
How to PreTrim Triangle & 45º Diamond Points, Using the PrepTool
You will learn on this page how to pretrim, so you can make these blocks accurately.
The PrepTool:
Point trimmer & Scant ¼" Marking tool
The PrepTool:
Point trimmer & Scant ¼" Marking tool
The Lip Edges on the PrepTool catch the fabric's edge, making it easy to accurately line up & pretrim points.
The Lip Edges on the PrepTool catch
the fabric's edge, making it easy to
accurately line up & pretrim points.
Mark an accurate Scant ¼"
+ Trim Points
PrepTool with 8page
booklet & 1 Seam Guide
$11.95
Square up the super easy way
cut & sew accurately
Perfect4Pattern Sets with
1, 2 or 3 Guidelines Ruler(s)
Square up the super easy way
cut & sew accurately
Perfect4Pattern Set for
regular acrylic rulers
Square up the super easy way
cut & sew accurately
Plus: Make Blocks Any Size
No Math!
FinishedSize Quilting Sets
Mark an accurate Scant ¼" + Trim Points:
PrepTool with 8page
booklet & 1 Seam Guide
Square up the super easy way, cut & sew accurately:
Perfect4Pattern Sets with
1, 2 or 3 GuidelinesRuler(s).
All you need to know about pretrimming
If you've worked with Triangles at all, you have definitely trimmed off a few Dog Ears, Bunny Ears or Triangle Points which all mean the same thing.
But most often you've probably trimmed them after you've pressed two Half Square Triangles open into a Triangle Square. When you do that, the Triangle Points are just poking out beyond the edge of the square and it's easy to see where to trim them off.
But there are times when
pretrimming the points is the way to go.
A good example is if you are sewing a triangle to a square.
The trick is to get the Triangle perfectly centered on the Square.
But because the edges don't match, you have to try to line it up by eye.
Before we get into instructions, let's talk about what pretrimming is all about. Scroll down if you want to see instructions.
If you've worked with Triangles at all, you have definitely trimmed off a few Dog Ears, Bunny Ears or Triangle Points which all mean the same thing.
But most often you've probably trimmed them after you've pressed two Half Square Triangles open into a Triangle Square. When you do that, the Triangle Points are just poking out beyond the edge of the square and it's easy to see where to trim them off.
But there are times when
pretrimming the points is the way to go.
A good example is if you are sewing a triangle to a square.
The trick is to get the Triangle perfectly centered on the Square.
But because the edges don't match, you have to try to line it up by eye.
You can look at it this way. These Triangles are the same Finished Size as the Square and if you sew them together it will be the same seam line joining them.
If you look at the seam line on the Square, it is a Scant ¼" from each edge. So if you were to measure a Scant ¼" from the end of the seam line on the Triangle, that is where you would want to trim off the point.
The bottom line to all this is, the edges of Squares and Triangles that are the same Finished Size, should match exactly after you accurately trim the Triangle Points.
If you accurately trim the points on Half Square Triangles and Quarter Square Triangles, their edges will match with a Square that is the same finished size.
You can look at it this way. These Triangles are the same Finished Size as the Square and if you sew them together it will be the same seam line joining them.
If you look at the seam line on the Square, it is a Scant ¼" from each edge. So if you were to measure a Scant ¼" from the end of the seam line on the Triangle, that is where you would want to trim off the point.
The bottom line to all this is, the edges of squares and triangles that are the same Finished Size, should match exactly after you accurately trim the Triangle Points.
If you accurately trim the points on Half Square Triangles and Quarter Square Triangles, their edges will match with a Square that is the same finished size.
Square up the super easy way, cut & sew accurately using your quit rulers:
Perfect4Pattern Set with Free Gift
Square up the super easy way, cut & sew accurately. Plus: Make Blocks Any Size
No Math!
FinishedSize Quilting Sets
Long Side Trim:
Line the PrepTool along the Long Side of the Triangle
Short Side Trim:
Line the PrepTool along the Short Side of the Triangle
So which trim should you use?
You can usually tell by lining up the triangle to the piece you are trying to sew it to.
You should be able to see which way will make the edges match before you trim the points.
Example: Trimming Triangles for SquareinaSquare Units:
To make patches out of 3 or more triangles,
you may want to cut your squares into triangles first
If you cut a Square in half once diagonally, you'll make 2 Half Square Triangles. If you cut a Square in half twice diagonally, you'll make 4 Quarter square Triangles.
Start by cutting a strip into Squares
Color coded Purple
Cut the Square once diagonally to make 2 Half Square Triangles
Color coded Green
Cut the Square twice diagonally to make 4 Quarter Square Triangles
Color coded Red
A Double Friendship Star has 4 patches that are made of one HST and two QSTs.
We call them 3Part Squares because each patch has 3 triangles.
Double Friendship Star
ColorCoded Breakdown
3Part Squares
An Ohio Star has four 4Part Squares
that are each made of four QSTs
Ohio Star
ColorCoded Breakdown
4Part Squares
It makes it easier to line triangles up when making 3 or 4 part squares.
Use a Short Side Trim on the half square triangles & Long Side Trim on the quarter square triangles.
Short Side Trim:
Line the PrepTool along the Long Side of the HSTs
Long Side Trim:
Line the PrepTool along the Long Side of the QSTs
They'll line up easier, and sew together easier.
It's also make it easier to sew the triangles together when you don't have to start on the points of the triangles. The points can get caught in the feed dogs of your sewing machine making it hard to sew in a straight line.
Step by Step Instructions
Step by Step Instructions
Long Side Trim:
Line the PrepTool along the Long Side of the Triangle
Short Side Trim:
Line the PrepTool along the Short Side of the Triangle
So which trim should you use?
The examples below are for trimming triangles for SquareinaSquare Units. Here we compare the results of using the Short Side Trim and Long Side Trim. The obvious choice is the Long Side Trim.
You can usually tell by lining up the triangle to the piece you are trying to sew it to.
You should be able to see which way will make the edges match before you trim the points, but we will show you more examples below.
To make patches out of 3 or more triangles,
you may want to cut your squares into triangles first
If you cut a Square in half once diagonally, you'll make 2 Half Square Triangles. If you cut a Square in half twice diagonally, you'll make 4 Quarter square Triangles.
Start by cutting a strip into Squares
Color coded Purple
Cut the Square once diagonally to make 2 Half Square Triangles
Color coded Green
Cut the Square twice diagonally to make 4 Quarter Square Triangles
Color coded Red
A Double Friendship Star has 4 patches that are made of one HST and two QSTs. We call them 3Part Squares because each patch has 3 triangles.
Double Friendship Star
ColorCoded Breakdown
3Part Squares
An Ohio Star has four 4Part Squares
that are each made of four QSTs
Ohio Star
ColorCoded Breakdown
4Part Squares
It makes it easier to line triangles up when making 3 or 4 part squares.
Use a Short Side Trim on the half square triangles & Long Side Trim on the quarter square triangles.
Short Side Trim:
Line the PrepTool along the Long Side of the HSTs
Long Side Trim:
Line the PrepTool along the Long Side of the QSTs
They'll line up easier, and sew together easier.
It's also make it easier to sew the triangles together when you don't have to start on the points of the triangles. The points can get caught in the feed dogs of your sewing machine making it hard to sew in a straight line.
Brave New World units are a combination of:

1 Big Half Square Triangle

2 Small Half Square Triangles that are half the size of the big HST.

1 Square that is the same size as the small HSTs
Use both a Short Side Trim and Long Side Trim
to accurately line the triangles up to the square.
Use a Short Side Trim on one HST
Line it up to the square and sew right sides together
Use a long Side Trim on the other HST
Now the square and two small HSTs are ready to be sewn to the big HST
You can then trim the points on the big HST and the unit you sewed together so their points won't get caught in your feed dogs.
Brave New World units are a combination of:

1 Big Half Square Triangle

2 Small Half Square Triangles that are half the size of the big HST.

1 Square that is the same size as the small HSTs
Use both a Short Side Trim and Long Side Trim to accurately line the triangles up to the square.
Use a Short Side Trim on one HST
Line it up to the square and sew right sides together
Use a long Side Trim on the other HST
Now the square and two small HSTs are ready to be sewn to the big HST
You can then trim the points on the big HST and the unit you sewed together so their points won't get caught in your feed dogs.
Double trimming makes it easy to line up two diamonds or a diamond and a square.
Double trimming makes it easy to line up two diamonds or a diamond and a square.
The PrepTool takes the guesswork out of marking precise seam lines.
Patterns often tell you to stop a ¼” from the edge of the fabric. What they really mean is stop right at the seam line, which is a scant ¼”. That’s the secret to sharp mitered binding corners and precise set in seams.
The PrepTool takes the guesswork out of marking precise seam lines.
Patterns often tell you to stop a ¼” from the edge of the fabric. What they really mean is stop right at the seam line, which is a scant ¼”. That’s the secret to sharp mitered binding corners and precise set in seams.
Quilts Made Using PrepTool by Guidelines4Quilting
Bonnie Beaty  CA Road to California Contest Entrant
"It was such a wonderful experience for me to take the leap and enter this quilt at Road. I am fairly new to quilting and to have my quilt accepted was quite an honor. This quilt truly stretched my quilting abilities and improved my confidence greatly.
I used a few of the tools offered by Guidelines4Quilting. I used the Guideline Rulers to cut the strips. I really like the ability of butting the ruler up to the fabric and knowing that it is straight and square.
I used the PrepTool to prepare the triangles. The PrepTool really does make for more accuracy when sewing triangles together and I needed accuracy on the triangle units of this quilt. Triangles have always been a bit of a challenge for me, so having tools that make it easier and actually work is great.
I tell everyone about Guidelines Rulers and at a recent quilt retreat I gave a demo on the Rulers, PrepTool and Grip Strips. I have the Grip Strips on almost all my rulers and just ordered another two packages for the rest of them. Thanks for the great products.”
This beautiful Lemoyne Star quilt was made by Sharon Vervoort of California and it was accepted into Road to California. It's the first quilt she had ever entered in a contest and it took third place.
She says one of her secrets to win this award was using the PrepTool to mark the seam intersections for the precise SetinSeams on the Lemoyne stars. Congrats, Sharon!
Quilts Made Using PrepTool by Guidelines4Quilting
Bonnie Beaty  CA Road to California Contest Entrant
"It was such a wonderful experience for me to take the leap and enter this quilt at Road. I am fairly new to quilting and to have my quilt accepted was quite an honor. This quilt truly stretched my quilting abilities and improved my confidence greatly.
I used a few of the tools offered by Guidelines4Quilting. I used the Guideline Rulers to cut the strips. I really like the ability of butting the ruler up to the fabric and knowing that it is straight and square.
I used the PrepTool to prepare the triangles. The PrepTool really does make for more accuracy when sewing triangles together and I needed accuracy on the triangle units of this quilt. Triangles have always been a bit of a challenge for me, so having tools that make it easier and actually work is great.
I tell everyone about Guidelines Rulers and at a recent quilt retreat I gave a demo on the Rulers, PrepTool and Grip Strips. I have the Grip Strips on almost all my rulers and just ordered another two packages for the rest of them. Thanks for the great products.”
This beautiful Lemoyne Star quilt was made by Sharon Vervoort of California and it was accepted into Road to California. It's the first quilt she had ever entered in a contest and it took third place.
She says one of her secrets to win this award was using the PrepTool to mark the seam intersections for the precise SetinSeams on the Lemoyne stars. Congrats, Sharon!