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Orianna2000
06-30-2017, 05:47 AM
This is going to sound insane, but I'm struggling to draw an accurate rectangle. When sewing, I often draft my own patterns, and a lot of the time, I need a square or rectangle. I use a transparent quilter's ruler that's 18" x 2". First, I draw a straight line with the ruler. Then I square the ruler off, using one of the inch lines, and draw a perpendicular line. I square off at the other end and draw another perpendicular line. But when I go to connect the two ends on the other side of the rectangle, I can't draw a direct line between them, because they're off. One edge always slants, instead of being straight. I don't understand this, because I'm using a straight ruler and squaring it off! I double-checked that my ruler isn't crooked, and it's fine. I even bought an L-shaped ruler specifically to combat this problem, and I still end up with crooked rectangles.

Now, I do have dyscalculia. I have a really hard time with numbers, measuring, and math, among other things. But it doesn't quite explain the issue I'm having, because it doesn't matter how long or wide the rectangle is. I always square it off, so the edges should always be perfectly straight. Yet they're not!

Does anyone have any idea what I'm doing wrong? Or should I file it under, "The geometry gods hate me," and give up?

cornflake
06-30-2017, 06:18 AM
I'm not sure what you mean by squaring off your ruler, but I'm guessing you mean placing it against the line you drew.

You're... tilting the ruler, heh.

If you have an L or a T-square, you should be fine though. Your problem is you're tilting because you're doing it in space. It doesn't have to be much of a tilt to throw it off. If you place one edge of the L or the bottom of a T against the edge of a table (every time, you have to turn the fabric or paper to use the table to make the second line), it shouldn't happen.

Alternately, do you have a gridded mat? I'm sure you know, since you sew but... They make mats for quilting with grids that you can cut on, use a rotary on, and you could line up on those...

Maryn
06-30-2017, 05:32 PM
I agree, it sounds like the slightest tilt of the squared end when you line things up. I'd seriously consider a large metal T-Square or L-Square like woodworkers use. Home Depot has a Steel Framing Square (http://www.homedepot.com/p/Empire-16-in-x-24-in-Steel-Framing-Square-1110/100204103) 16" on one edge, 24" on the other, for less than $7, that could solve the problem.

Another aid, besides the gridded mat (I need a much bigger one, like the size of the dining room table with the leaf in), is interfacing-like material made for creating patterns with the grid printed on. You could use it just for the things you need to be squared, or for the whole pattern.

Pattern Ease
Pellon 830 Easy Pattern
Pellon Tru-Grid 810
Pellon 815 Red Dot

JoAnn Fabrics carries the 830 locally (I haven't checked their website) and it's a good use of one of those 50% or 60% off one item coupons. I buy the whole bolt, usually, since I'm now sewing for someone so tall I have to modify every pattern except loose skirts.

Maryn, who has has similar problems with her lone quilting attempt

Orianna2000
06-30-2017, 06:52 PM
By squaring off, I mean that I'm lining up one of the inch lines on the transparent ruler with the line I drew, so the ruler is perpendicular to the line. The ruler is 2" wide and has marks on both edges, so I line up both edges with the line, which SHOULD produce a perfectly perpendicular line. Except it doesn't.

I do have a L-square ruler, but it does the exact same thing! I draw two perpendicular lines with the L-ruler, then draw the other lines, but when I go to draw the final line to form a square or rectangle, one of the lines is slanted. Every time. It defies all sense and logic.

Maryn, I do have a gridded mat, never thought to use it for making squared patterns! Would it work with non-transparent fabrics or drafting material? Sometimes I draft directly on my mockup muslin. I'm guessing it wouldn't work for that? Also, the grid lines may be too far apart for the small things I draft. But it may work for larger patterns. I'll have to remember to try it, thanks! As for the gridded pattern material, I suspect it would have the same problem, too large of a grid for my doll patterns, but I will definitely look into it. Just checked Amazon . . . wowee! That stuff is expensive!!! Fabric.com has it for a lot less money. Which is weird, considering that Amazon owns Fabric.com. I'll order a couple yards to try it.

I'm half-convinced this is all due to my dyscalculia, that I'm doing something wrong. Anything to do with numbers and I'm doomed. I also thought it might be my ruler, that it had warped somehow, but I checked it against the edge of my cutting table and it looks perfectly straight. Why do all the weird sewing things happen to me???

cornflake
06-30-2017, 07:11 PM
A gridded mat should help even with opaque fabric -- if you put the fabric on and then line your ruler up to the SAME (heh) line above and below the piece of fabric you're cutting, you should have a totally straight line you can either cut with a rotary cutter or draw on the fabric and cut. That way the ruler isn't operating off one line (in which case it can tilt), but a top and bottom that are the same line. If the mat is pinnable, can use pushpins (the office supply type) to just mark the lines and butt your ruler up to -- the tops of the pins will hold it down for you.

You can tilt an L too, if you're using it in space (not grounded against an edge). It doesn't take much of a tilt to throw something off, and you'll think it's straight because it's an L. If you always line one edge of it up against the edge of the table (carefully), it won't happen.

Orianna2000
06-30-2017, 08:14 PM
Okay, thanks. I'll try again today and see what happens.

blacbird
07-02-2017, 06:21 AM
The ruler is 2" wide and has marks on both edges, so I line up both edges with the line, which SHOULD produce a perfectly perpendicular line. Except it doesn't.

It doesn't, because that 2 inch distance isn't nearly long enough to establish a reliable 90 degree angle for your cross-line. You really need a T-square or something like that, which will establish a standard 90-degree angle.

caw

Filigree
07-02-2017, 08:30 AM
I live by my T-Squares. And I need multiple marks at least 8-12 inches apart to keep from drift. The other thing to do is make templates of common pieces out of sturdy plastic or heavy cardstock...I do that for quilting foundations and book forms, so I don't have to keep remeasuring stuff.

Orianna2000
07-02-2017, 05:27 PM
Blacbird, I have an L-square, as I said, and it doesn't seem to make a difference. My rectangles still end up crooked.

Filigree, unfortunately, I can't use 8-12 inch marks as a guide because the things I make are quite small. Just as an example, what I'm working on now, the rectangular part is something like 6" by 8". And that's on the big side for me. The doll pencil skirts I make are maybe 3" by 6", at most. Which means any mistakes have a greater impact, because when you're working in doll-scale, a sixteenth of an inch off can make the difference between on-grain or off-grain, or fitting and not fitting.

I've tried drawing one line, then measuring up from it every inch or so across, so I have a guide for the parallel line. Then I draw the sides, after squaring off. This seems to help--sometimes. But not always. And sometimes, my parallel marks don't line up with each other, even though I measured the same distance from the first line for each mark. It's like my ruler changes length every time I use it.

Old Hack
07-02-2017, 08:14 PM
I have several quilters' rulers (I make quilts!) and I find they're useful for reasonably large pieces of work but they are not reliable when trying to be very precise because often the markings are printed on the top of the rulers, and the rulers are several mm thick. Unless you look at them from directly above when working, and find the same vantage-point every time, measurements are going to be off.

Also, I've found that unless I use the same brand for everything, I can't swap between rulers in one project. A quarter-inch on one brand of ruler is not the same as a quarter-inch on another, and although the difference is usually minimal it's still there.

I have some where the markings are on the base of the ruler and these are more accurate. The best thing I've found to use is a metre-long metal ruler, and a metal L-shaped ruler. But it is difficult to draft a perfect square or rectangle, even so.

Orianna2000
07-02-2017, 08:50 PM
Hmm. The main ruler I use is maybe 1mm thick at most. It's not super thick and rigid like the quilter's template rulers or the kind you use with a rotary cutter. Still, it's good to know that thicker rulers will be less precise.

I have noticed that when I mark quarter-inch seam allowances with my ruler, then take it to the sewing machine and use a quarter-inch presser foot, the needle doesn't line up with the lines I drew. I always just assumed my presser foot was inaccurate, since I ordered it from China for $2. I'll have to compare my other rulers to see how consistent the error is.

Old Hack
07-02-2017, 08:55 PM
It's likely your presser-foot is also inaccurate: they're notorious for this. It's wise to do several test-seams to check your foot, adjusting the needle position by tiny amounts each time. But that doesn't mean your ruler is accurate--both might well be off.

Filigree
07-03-2017, 05:21 AM
Check out smaller drafting rulers from art supply stores (metal, preferably). The markings are quite narrow and precise. I use those for project under 10" (most of my bookforms).

Layla Nahar
07-03-2017, 06:11 AM
Is a twisted grain throwing things off? I've noticed that a lot of fabric doesn't actually have the warp and weft at 90 degree angles...

Filigree
07-03-2017, 12:06 PM
Oh god, yes. It's so bad with some fabrics that I iron them flat, stiffen them with spray starch, or resort to ignoring the grain entirely & just mark every edge. Starch + templates often works wonders.

Layla Nahar
07-03-2017, 02:24 PM
starch, huh? I inherited a bunch of cheap fabric - I just use it for mock ups. I learned a lot about bad grains from that. I'd tear off a big chunk of fabric from the bolt and then fold it in half - it was ridiculous how not at a right angle (ETA - ugh. I'm hoping everyone figured out I meant 'parallel') the two edges were...

Maryn
07-03-2017, 05:34 PM
(I have a two-thirds complete top with the grain so far off it's ruining my efforts. I thought the steps I took when cutting out were enough, but no-o-o-o!)

Orianna2000
07-03-2017, 05:45 PM
You know, the other day I wondered if it could be the muslin's grain throwing off the squares, but I couldn't figure out how, exactly, it could do that. I mean, if I cut the squares out and they were crooked, yes. But this is just drawing them on the fabric, so I would imagine they'd still measure straight, even if the grain was off. But I could be wrong?

I gave up using spray starch a few years ago, when my iron started dripping an oily substance onto my fabrics. Never did solve that mystery, but for awhile I suspected it was starch that had turned to steam and got inside the iron. When it happened with a brand-new iron, I knew it couldn't be the starch, but I'm still nervous about using it again, just in case.

Old Hack
07-04-2017, 12:15 AM
Fabric is often crooked on the bolt. If you tear it off you can see that you've got a straight tear, along the grain, and it's rarely perpendicular to the selvage. I've spent far too long working out what to do: I've found that to get it properly square I have to wash and press it very thoroughly. Spray starch is useful here (I remember your iron problem, Orianna), but not obligatory.

Luckily my quilts are not that dependent upon squared-up fabrics. I am a very relaxed quilter.

Layla Nahar
07-04-2017, 07:54 AM
It *can* also help to pull the fabric across the bias, so grabbing one corner and the opposite corner and stretching the fabric. Then after that the washing & ironing etc...