The Upholstery Forum

I can't believe I've been cutting Sunbrella and Cordura fabrics with a rotary cutter and utility knife! I just got a hot knife a couple of weeks ago and can't believe how much better that is with these fabrics. But I'd like to know what you guys use as a cutting guide when using a hot knife.

I had been using both plastic rulers and a 6 foot long aluminum bar (1/2" x 2") both to cut against and to draw my straight lines. But with the hot knife I have so far been cutting freehand. And that's been working pretty well (steady hand I guess). I'm reluctant to cut against the plastic rulers I have in fear of melting them. And if I cut against the aluminum bar I am afraid that the heat of the hot knife might dissipate too much. My cutting surface under the material I'm cutting is a piece of tempered glass I got from a hardware store.

Do any of you use something to cut against with a hot knife? Any suggestions?

Thanks.

1/4" X 3" piece of hard wood, the cheaper cut. Home depot and the like carry cheap hardwood, ash or elm. If oak is the only thing they have then that's it. Less of a chance for a hardwood to twist and warp over time like pine would.

Thank you @Rug Dr. ,'

No worry about burning the wood? That hot knife gets red hot.

No, I've had a wood burning kit, it takes time to burn ash or elm. If you're sitting there long enough to burn wood your material should be on full blaze.

Yeah hot knifes are essential for things like sunbrella. Mine has a guard that holds blade up of your table do that it wont damage your table. What style do you have?

@John - Somehow I had missed your reply. Sorry.

My hot knife looks like yours and it did come with a similar guide. I haven't tried it because it looked like very careful adjustment would be needed to both prevent cutting down into the table surface (or whatever you're cutting on) yet cut deep enough to cut the fabric. Or am I missing something about using that guide?

Or does that flat part go UNDER the material you're cutting?

Little "foot" does go under the material and keeps the hot blade off your table. We just let our plywood table tops get scarred up with hot knife marks. They do have several coats of urethane, certainly adds to their longevity, but no fires

Adam12 wrote: ↑Thu Dec 16, 2021 10:47 pm Little "foot" does go under the material and keeps the hot blade off your table. We just let our plywood table tops get scarred up with hot knife marks. They do have several coats of urethane, certainly adds to their longevity, but no fires

I didn't know that. I'd just assumed the "foot" was to glide over the fabric being cut and that the hot knife blade had to be adjusted to the exactly correct depth.

But using it the way you say means it is harder (or even impossible) to cut against a guide (thanks to this thread I'm using wood strips that are only 1/4" thick). That means I'd have to actually mark my fabric so I could follow the line.

In any case, I'm pretty happy with the setup I have now... using those wood strips (I have 2", 3" and 4" wide strips by 48") I'm able to cut my most common strap and other component pieces. On top of a piece of tempered glass.

Great forum here... lots of helpful folks with great advice and experience. Thank you.

@Mtl_Biker , I agree with you it is a great forum

Yep the flat part is to protect your table surface. When I first started out I used my parents ping pong table for a few year to cut canvas with the hot knife and it never damaged the table once.
When I got glue on it that was a different story though....