Thank you for purchasing my Gemology quilt pattern. Here are instructions on how to trim your 4-1/2″ x 12-1/2″ HRT units.
Read ALL of these instructions. Don’t trim anything until you know how to center and check the block length first!
I recommend making a test block with scrap fabric to practice this method before making your pattern blocks.
I also recommend checking you have an accurate 1/4″ seam allowance (see this post).
First up, trim the long edges of the HRT unit so it’s 4-1/2″ wide.
The following trimming method is easiest if you choose a quilting ruler where the 1/4″ marks have been extended until they intersect, as you can see on my ruler below:
The HRT blocks need to be 12-1/2″ long.
First, I’ll show you how the blocks would be trimmed if they were sewn perfectly.
Next, I will show you how you should trim the blocks given that perfect rarely happens!
Finally, I’ll outline troubleshooting methods.
Assuming perfect blocks: Take your ruler and start at one of the corners with a diagonal seam. Line up one edge of the ruler with the long edge of the HRT. Then slowly slide the ruler along the unit (keeping the ruler/block edge lined up) until you find the spot where the diagonal is exactly a quarter inch from the long edge.
The part of the HRT extending past the top of the ruler can be trimmed. Because the diagonal is a quarter inch from both edges, when it is sewn together with another unit the diagonal will form a lovely point.
Turn the HRT around and repeat the process with the other corner.
Before you trim the top off the opposite side you need to make sure your block will measure 12-1/2″ long when trimmed. See the block below – the diagonal is right under the 1/4″ crosshairs and the bottom of the unit is on the 12-1/2″ mark of the ruler. Perfect!
This edge is also now trimmed:
Now, what happens if the HRT is NOT 12-1/2″ long when the second diagonal is under the 1/4″ crosshairs? Here are tips for trimming less-than-perfect blocks:
I recommend centering your block across the required 12-1/2″ of length so you can test both ends of the HRT before you trim. The block below has been centred on the cutting mat in this way (just with the naked eye) – there is 12-1/2″ between the arrows and even amounts of “point” overhang each side.
The diagonal can now be quickly checked at each end (with the 1/4″ crosshairs) and the block nudged up or down as required before the final trim is made.
This trimming process is the same whether making left or right slanting HRTs. Here’s what it looks like for the HRTs facing the other direction:
Trim edges parallel to 4-1/2″:
Centre the block on 12-1/2″ to test the diagonal at each end. Adjust block as/if necessary.
Find the spot 1/4″ from the long edge and trim:
Rotate and repeat on 2nd corner; make sure block is 12-1/2″ long:
- if your block isn’t wide enough, your seam might be wider than 1/4″.
- if your block is too long, your seam could be too scant.
- if your block is too short, your seam could be too wide.
- if your tips are wonky, try using a stiletto to hold fabric when sewing close to the needle and using a leader (a small scrap piece fed through before your block to stop your block being distorted/pulled down into the feed dogs of your sewing machine.)
You’ve got this! Use this method to trim all your blocks and complete your Gemology quilt.