Help! How to cut Foamboard properly?

[PsyBorg]

I got to disagree with the angle thing. I think the angle you use depends on the cut you make. when I hold the razor blades I cut straight cuts at 45 degree angle on the blade. For rounded edges I hold straight up and use very short sawing strokes out near the tip of the blade.

The key to ALL cuts is consistent pressure and speed as well as blade sharpness. Granted I am no master builder but I do have the patience to be a semi perfectionist in anything I take on. this was the hardest piece for the edge I built. all done by hand with a single razor blade. In fact I have made five of these now at this point in my attempts to fly.

It all boils down to sharp blade and not rushing to do the job.

 

[sprzout]

I got to disagree with the angle thing. I think the angle you use depends on the cut you make. when I hold the razor blades I cut straight cuts at 45 degree angle on the blade. For rounded edges I hold straight up and use very short sawing strokes out near the tip of the blade.

The key to ALL cuts is consistent pressure and speed as well as blade sharpness. Granted I am no master builder but I do have the patience to be a semi perfectionist in anything I take on. this was the hardest piece for the edge I built. all done by hand with a single razor blade. In fact I have made five of these now at this point in my attempts to fly.

It all boils down to sharp blade and not rushing to do the job.

View attachment 188241

I understand and agree with what you're saying; when I'm talking about angling the blade, I mean not to tilt it left or right, especially in a straight line, or else you run the risk of beveling the cut, and things won’t sit right. Made that mistake several times when I was first scratch building.

Cut like this:

not like this:

Does that make sense?

 

[PsyBorg]

@sprzout Pretty much exactly what I said I do except I don't use a bulky handle just the blade and can see exactly what I am cutting. for circle cuts I keep the blade square to the foam and the blade vertical or 90 degrees using the reference previously used in other posts.

All initial cuts I make are square to the foam, any beveling comes after the pieces are cut and I do minimal cuts at that and finish the bevel with a foam backed emery board.

EDIT guess there is no consistency in the thread over angle and tilt in regards to the blade.

 

[leaded50]

I tried using a brand new blade


I already do 10-15 passes and it still does that, and I do use a ruler

Plastic may help I guess. I use a similar blade as you. My blade (I think) doesn't flip over to use the other side. Thanks \\\\\\\\\\\\anyways! it may be the blade I am using- it says that its for heavy duty.
https://www.amazon.com/dp/B01MSWKPKF/?tag=lstir-20
Will using a dedicated craft knife like this help?
Thanks!

also rememeber try hold blade at an angle in direction you draw.

 

[sprzout]

@sprzout Pretty much exactly what I said I do except I don't use a bulky handle just the blade and can see exactly what I am cutting. for circle cuts I keep the blade square to the foam and the blade vertical or 90 degrees using the reference previously used in other posts.

All initial cuts I make are square to the foam, any beveling comes after the pieces are cut and I do minimal cuts at that and finish the bevel with a foam backed emery board.

EDIT guess there is no consistency in the thread over angle and tilt in regards to the blade.

Lol a lot of it comes down to ergonomics, I think, and we all have different techniques that work to get the job done. 😁 I use a utility knife just because I don't have the best dexterity, and I'd likely end up cutting one of my fingers trying to hold the naked blade. I tend to use Exacto knives more than utility knives because i can hold it more like a pencil for cutting; again, what works for me.

 

[Hoomi]

Rotary Cutters. The small one is from the Sewology line at Hobby Lobby. It's just about the exact cutting depth for the score cuts. One distinct advantage of the circular blades is that you cannot have the blade at a perpendicular angle to the cut. It will always be angled, making for an easier, smoother cut.

 

[The Hangar]

Rotary Cutters. The small one is from the Sewology line at Hobby Lobby. It's just about the exact cutting depth for the score cuts. One distinct advantage of the circular blades is that you cannot have the blade at a perpendicular angle to the cut. It will always be angled, making for an easier, smoother cut.
View attachment 188290

How do you deal with the spring-loaded plastic “safety” part? It seems like you could end up creasing the foam pretty heavily from it...

 

[PsyBorg]

How do you deal with the spring-loaded plastic “safety” part? It seems like you could end up creasing the foam pretty heavily from it...

better yet how do you do corners and bevels...or rounded edges for that matter.

 

[MCNC]

I made a leather strop from an old belt and a piece of wood and contact cement. Keeps the edge clean and removes the telltale drag you feel as it dulls. Do a search for some methods.

 

[Hoomi]

Neither of my rotary cutters has a spring-loaded blade guard. The guards are manually retracted before using.

As I mentioned in my first post about them, I use the rotary cutters for straight cuts. I use either a single-edged razor blade for the curved cuts, or an X-acto knife. I do the bevels with the razor blade, sometimes fine-tuning the bevel with a sanding block.

 

[TheFlyingBrit]

Scalpel blades, if its good enough to use on flesh and internal organs its good enough for my planes.
I replace blades several times during a build, the angle is critical to a smooth cut. I also find scoring the paper layer in the first cut with the tip of the blade helps.

 

[tesseract]

Scalpel blades, if its good enough to use on flesh and internal organs its good enough for my planes.
I replace blades several times during a build, the angle is critical to a smooth cut. I also find scoring the paper layer in the first cut with the tip of the blade helps.

Uhh okay! thx

 

[TheFlyingBrit]

I use a number 3 scalpel handle with #11, #10 and #10a blades dpending on the area I am cutting. The None sterilised blades are quite cheap I buy them in packs of 20 or 30 at a time.

 

[The Hangar]

Neither of my rotary cutters has a spring-loaded blade guard. The guards are manually retracted before using.

As I mentioned in my first post about them, I use the rotary cutters for straight cuts. I use either a single-edged razor blade for the curved cuts, or an X-acto knife. I do the bevels with the razor blade, sometimes fine-tuning the bevel with a sanding block.

Interesting, I'll have to give that a shot - thanks for the suggestion.