How do you make straight cuts on lightweight fabrics?

Erict

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Any tips for making straight cuts of lightweight fabric like, say, 1.1 silpoly? These are longer cuts, say anywhere from 10-70". I have done a handful of projects using similar lightweight materials and find it near impossible to cut a "perfect" square/rectangle. The warp/weft always seems to pull a bit and I end up with an odd shape. While I can simply cut off the odd shapes when done, it does make it harder to sew two edges together straight when neither one has a straight edge. Do you weigh it down somehow?

Secondly, what is a good method for marking such lightweight material? I have fabric pencils but they really don't write to well on such fabrics.

Thanks in advance.
 
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reaper

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Any tips for making straight cuts of lightweight fabric like, say, 1.1 silpoly? These are longer cuts, say anywhere from 10-70". I have done a handful of projects using similar lightweight materials and find it near impossible to cut a "perfect" square/rectangle. The warp/weave always seems to pull a bit and I end up with an odd shape. While I can simply cut off the odd shapes when done, it does make it harder to sew two edges together straight when neither one has a straight edge. Do you weigh it down somehow?

Secondly, what is a good method for marking such lightweight material? I have fabric pencils but they really don't write to well on such fabrics.

Thanks in advance.
I use a long metal meter and hot knife(electric)to cut straight or a really sharp knife.

I use a fabric pensil,sounds weird but I found it perform better by licking it before making my marks lol...god that's sounds weird.It works great with silnylon and cordura fabric.

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nodakian

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Sharpies worked for marking the few projects for which I've used that lightweight stuff. I wonder if a straight edge backed with cork or a rubbery material would work to hold it down?
 

eagle_eye

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For my tent(diy stretched TUT) I had to mark 9' lines. I used small weights on the corners and strung a line from corner to corner to draw the line. Every 3 feet or so I put a mark with a sharpie under the line onto the fabric. I then used a straight edge as a guide between the marks and used a rotary cutter to cut between the marks, creating a straight nine foot cut. The cutting surface is one of those self healing cutting boards as mentioned above. Make sure that you put enough pressure on the straight edge so that fabric doesn't move while you cut.
 
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hereinaz

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Weigh it down on the floor, making sure it is square with lots of spots weighed. Use a long long straight edge and sharpie. Once marked, then use a hot knife off Amazon. Hot knife is so much better for the edge and easier than a rotary knife. Scissors are the worst, IMO. Hot knife nicely fuses the pieces together when you trim after sewing.
 

Dan74

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Use hair spray our starch to stiffen up fabric then you can mark easier and get a good straight cut
 

Ehiggins

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I made a template out of metal corner bead and traced lines with a sharpie first. Then used a big cutting board and sharp knife to follow the lines. Worked great.
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mereside

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I just use a long straight edge then a rotary cutter or some proper material sheers and start the cut and push along the line, some materials though need proper cutting , scissors like these are great.
 
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Erict

Erict

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Some great ideas/tips from y'all. I have used a good mat and rotary cutter but have to do a better job weighing everything down. Thanks.
 

Hunt_UP

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Thanks for the tips, getting ready to make some game bags and I have been wondering the same thing.
 

Hunt_UP

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Feb 18, 2021
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Just thought I would make a follow up on this thread for a trick I found online for cutting/sealing ripstop nylon. The guy used a soldering iron, press against a metal straight edge and piece of scrap wood under the material being cut. Similar to a hot knife I am guessing. I bought a 5$ soldering iron and it is working great on 1.1 ripstop, cuts clean and seals edges. Also works for cutting para cord and sealing the ends off in one pass. Not as fancy as the hot knife, but 5$ is better than the 70-100 for the hot knife I was seeing for a few simple DIY projects.
 
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Just cut 1.1 silnylon this weekend for a tent and i used weights to hold fabric and then tailors caulk to mark it (dark green fabric and could not see a sharpie line at all) with a could 8' levels as my straight edge. Roller cutters work best but be careful of what's under you fabric they will cut through just about anything.
 
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