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Best Knives to Use?

Mhesche

New member
#1
Hello, I have been using a $10 X-Acto knife to cut foam but it gets caught in the foam and doesn't allow me to cut very straight lines. (Blades are sharp) Anyone have any better knives I could order online or find in a hobbyshop? Thanks!

P.S. Any tips on cutting straighter lines?
 

Mad_Mechanic

Well-known member
#2
Hello Mhesche!

I can't speak from personal experience on this topic (yet), but from watching a lot of Flite Test videos, I almost never see them using X-Acto knives to cut foam board. They seem to use (almost exclusively) utility knife blades. Not sure if this is an economic decision (like cost per blade) or if it's because of blade sharpness/longevity.
 

Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
#4
If 99% of the blade is sharp, but the 1% that isn't sharp is in the material tearing instead of cutting . . . then the blade isn't sharp "enough".

I still use #11's, and I've gotten them in 100 packs that work out to ~$0.20/blade, but when cutting out most models, I typically average swapping a blade every other board, but that isn't as much from wear rate as much as why it's no longer "sharp enough"

Most common blade damage until you know to look out for it? The broken tip. particularly if you're being bold and trying to cut all the way though on the first pass, it's VERY easy to make a sharp curve and feel a very subtle "ping". pull out the blade and you no longer have a point. it's now embedded in the cutting mat. because of the twisting break, the end now has a weird off-axis edge on the bottom that will drag and tear while the rest of the blade is cutting, so the next thing you cut will turn out horrid, even though the edge appears keen. How do you avoid it? shallow cuts, particularly on curves. I tend to take two passes for straight cuts -- first pass cuts the inside paper and a little more than halfway through the foam, then a second pass to finish the foam and *mostly* cut the outside paper. the idea being avoiding cutting the cutting mat any more than necessary. on curves, I hold the blade nearly perpendicular to the board (easier to turn around the radius) and make 3 cuts to make up for less blade in the material, with the final cut is generally done while lifted off the cutting board.

Second most common? For me, Adhesives. Trim off a piece of tape? Cut a hot glue seam? Cut through a tape-reenforced seam? usually something sticks to the blade as it cuts through. Usually, when the builds starts to getting to the clean-up stage is when I'll have to make a blade change, because the blade is now dragging from the gunk that's coating it's surface. In many cases it can't be avoided, but if you just swapped in a new blade, before you drop that old blade into the sharps box, consider keeping it out for these kinds of tasks to preserve your sharpest blade.

Now the utility knife blades are good alternatives for straight cuts -- far more forgiving and the tips are far durable, but they're a lot less friendly in turning around curves -- tradeoffs. If I'm building outside (usually at flitefests and such) they're a durable go-to, but back in the shop, hard to beat the feel of a fresh #11 blade in a good handle.
 

FDS

Well-known member
#5
I use Xacto type knives, since they are one I have used for years, you need to change the blade every 3 sheets of board. Paper in particular dulls the edge of blades really fast. For bevel cuts I use a Stanley type blade as shown above, with a steel rule.
Bevel cut like that-
image.jpg
 

sprzout

Knower of useless information
Mentor
#7
I waffle between the utility blades (I usually change out the blade every time I make a new plane) and the exacto knives. Exactos are great for the smaller curves, and I feel like I can draw more with a pencil type of feeling than I can with the bigger utility knives.

As for bezel cuts, there are multiple 3D printed tools out on Thingiverse that I have used; they work well at cutting straight bezels for a long aileron or rudder cut. Those use one of the utility blades in them, and again, after several uses, they lose what I think of as the "surgical sharpness" and need to be replaced to a new blade.

You can buy the blades really cheaply at places like Harbor Freight, but there IS a difference in quality. I've found the Harbor Freight utility blades that come in 50 or 100 to a pack don't last as long as the Stanley or Kobalt brands. But, the Stanley and Kobalts are a little more expensive, so there's the trade-off.

I would tell you to use what you feel most comfortable with, AND to make sure you dispose of the blades in a safe manner. I've got a blade safe that I made a few years back for my shaving blades (I use a safety razor with dual edge razor blades to shave) and it's basically an old juice bottle with a wide mouth. I took a dremel tool, made a slice in the lid that's wide enough for the blades to fit through (like a coin slot), hot glued the lid shut, and I drop the razor blades in. Since I've started doing the planes, I just use the same blade disposal bottle, and have about 2 years worth of razor blades in a 20 oz bottle, and it's only about 1/3 full; once it gets full, I'll throw some duct tape over the slot and throw the bottle away so that nobody gets injured from the blades. :)
 

FDS

Well-known member
#8
Knives are super personal tools. Nearly every model maker I know has a different one.
I used the Swan Moreton scalpels for years but you can’t get the blades easily where I live now. I like those for straight cuts and paper work.
Tips are always the first to go on scalpel type blades. Budget blades are faster to blunt. My theory is if I throw the blade away twice as fast was the lower price really a cost saving?
 

sprzout

Knower of useless information
Mentor
#9
Budget blades are faster to blunt. My theory is if I throw the blade away twice as fast was the lower price really a cost saving?
EXACTLY!!! If it costs $1-$2 more, but you get 5-6 uses out of them vs 2 uses, I'll definitely use the ones that are a little more expensive. :) I tried the Harbor Freight ones because I was there buying a utility blade and they had them on sale; when I was at Lowe's around Christmas they had a sale on the blades and so I picked those up and tried them, finding the Kobalts to be longer wearing (and I think they were marked as a "heavy duty" type of blade, too).
 

mrjdstewart

Well-known member
#10
get yourself one of THESE and then you can resharpen your blades and get 2x the life out of them. use the fine, ceramic sharpener and you will be amazed at how much longer the blade will last.

for the really fine cuts i use THESE and do the same thing when they dull. i have one that i have been using for months and it is still able to easily cut what i need.

laters,

me :cool:
 

JTarmstr

Well-known member
#11
I use a Husky Boxcutter and standard utility blades. As for straight lines I use an aluminum ruler or a steel straight edge depending on how long of a cut it is.
 

sprzout

Knower of useless information
Mentor
#12
I use a Husky Boxcutter and standard utility blades. As for straight lines I use an aluminum ruler or a steel straight edge depending on how long of a cut it is.
Yep. I use a 15" Westcott cork backed ruler for my straight cuts...I've thought about picking up a longer one, but haven't yet found a real need for it (or a place to store it!)
 

mayan

Well-known member
#13
AND to make sure you dispose of the blades in a safe manner.
You can also shove them in a scarp piece of FB, all they way through it does the job, that's what I do.
get yourself one of THESE and then you can resharpen your blades and get 2x the life out of them. use the fine, ceramic sharpener and you will be amazed at how much longer the blade will last.

for the really fine cuts i use THESE and do the same thing when they dull. i have one that i have been using for months and it is still able to easily cut what i need.

laters,

me :cool:
Never thought of sharpening my blades. Great tip.
 

sprzout

Knower of useless information
Mentor
#15
You can also shove them in a scarp piece of FB, all they way through it does the job, that's what I do.

Never thought of sharpening my blades. Great tip.
LOL I never seem to have big enough pieces to do that, or my cat is running off with the FB scraps. But if that works for you, go for it! :)
 

slipshift

Active member
#16
I really enjoy building from scratch so I got a couple of Olfa snap blade knives. The best feature is that the slide locks securely without having to tighten anything down. For small radii I use an Xacto knife. If you buy the blades on Amazon in bulk they are quite cheap. For straight lines I use a steel ruler ( 12", 18", and 36"). On the back I attach fine sandpaper with spray glue to make it non-slip.

Jim
 

Tench745

Active member
#18
I'm surprised no one else has mentioned it. I like to use single-edged razor blades: This style. They're much thinner than utility knife blades, so they don't drag as much or deform the surface as badly and the tips don't break off as easily as an x-acto. I use them for all straight cuts with a metal straight-edge and freehand wide curves. I'll then switch to standard #11 x-acto blades for cutting sharper curves. The snap-off blades are great for beveling things, gives you a lot of surface cutting at once but they dull pretty quickly as well.
Multiple passes to cut through something make a big difference no matter what knife you're using.
As others have mentioned, cheap non-brand x-acto blades seem to dull very quickly. A quick few swipes on a strop or diamond sharpening stone will keep a blade usable longer, but in my experience only works for so long.
 

Paracodespoder

Well-known member
#19
Like most here I use a cheap dollar tree snap off blade for long straight cuts and large curves (think sportster wingtips) and a #11 x-acto for tight curves.
 

buzzbomb

I know nothing!
#20
For me? The skinny blue one is kind of useless.

IMG_0212.JPG

Scissors and wire cutters, utility knives and bare blades. A rotary pipe cutter. This is what I'm currently using. I like the green one to cut plans, and the red one to cut foamboard. Unless it's a bevel, then I like the orange one. Sometimes I like the bare utility blade or the "safety" razor blade, depending on the curve of the cut. The rotary pipe cutter is awesome to cut barbecue skewers without dulling a blade, the multitude of scissors, and the wire cutter have their place as well.

Paper dulls a blade almost as fast as dragging it on concrete. Those tools pictured above that have replacement blades? I've got lots. If one were thrifty and skilled, I think you could do it all (minus cutting wire) with that red utility knife. You'd need lots of replacement blades, though.