Use planer to even out edge sawn with scroll saw?

So I was wondering if an electric planer would do a better job at making those edges straight?

Yes. In addition to being far far faster it is much more likely to result in straighter edges. It's possible a planer could straighten the edge pictured in just one or two passes, the work of perhaps 5 seconds.

Unfortunately details of how you'd do this work accurately and safely1 can't be provided because there are too many variables2 but yes in theory you can do this with one.

A hand plane would make this task much safer, and while it would take a little longer you could still be looking at under a minute. However, in addition to having to buy a plane as you clarified in the Comments if you don't already own suitable sharpening equipment you'd need to buy that too. And on top of learning how to use the plane itself you'd have to learn to sharpen well enough to produce a very good edge (something that many struggle with for a long time) in order for the plane to work properly. So while I'd favour this approach myself it's probably not the ideal recommendation for you, unless you already wanted to get into hand planing.

There is an elephant in the room though....

Wrong saw for this type of cut
I understand if the scroll saw is the only saw you have available you have to use it, but it's not well suited to this type of cutting. Scroll saws are made to do intricate, mostly curved cuts and struggle to do straight cuts of any length. Although various tricks can be used to help improve the results3 I'd still recommend looking at some options.

The simplest, cheapest and easiest is a hand saw of some kind. There are numerous decent options available that should cost around the €10 mark, and occasionally less4, with a range of tooth styles — Western, Japanese and a few modern hybrids.

With a sharp saw of any style a cut like this can leave a very good, flat surface that may require no further work depending on what you're doing. Nearly perfect dead-straight crosscuts and mitre cuts are possible with a fine-toothed saw used carefully, especially if the cut is done with the help of an aid such as a mitre block/mitre box, or a magnetic sawing guide which would be clamped to the workpiece.

1 Planers have spinning cutterheads that you want to be very careful not go get fingers near unless a guard can be improvised.

2 Much depends on the specific design details of the planer which are unknown. And then there are two basic approaches, moving the wood past the tool or moving the planer past the wood (similar to shooting done with a hand plane, often done with the wood held in a jig called a shooting board).

3 Simply clamping a straight piece of wood to the bed of the saw to act as a fence and running the wood along it would help a great deal.

4 E.g. from Lidl or Aldi.

There’s a lot of choice when it comes to rip saws.

And unfortunately options usually just make things more complicated.
So hopefully the video above will help clear up some of the confusion around which saw to reach for or at least give you something to think about when you’ve got a lot of ripping to get on with.

And I’ll jot out a bit of a summary below if you prefer to read.

Don’t Over Think It For Thin Rips.

I want to point out that ripping for many of your builds will be a doddle.
Let’s not make this seem more challenging than it actually is. If your projects are small or you’re knocking up carcasses with timber less than an inch thick then there’s no reason to sweat or over think it.

In these cases you have a lot of options that will whip through your timber nice and quickly.
Owt with rip in the the teeth will do.

So for now let’s just focus on the thick stuff.

Even after many years of challenging myself to come up with a pleasurable efficient method of ripping down thick chunks of timber by hand, it’s still a pig of a job!

Which is why my first suggestion is to get yourself a bandsaw!

The Bandsaw in the Hand Tool Workshop

Due to various workshop moves I haven’t always had a bandsaw but whenever I do get the opportunity it’s the first and only machine that I make space for.
It’s sole purpose in my workshop is for ripping.

The ability to rip down thick stock can help you make the most of the wood that you have to hand, and this will save you a lot of time at the very initial stage of prepping.

If your ripping needs aren’t enough to justify a machine then there’s still plenty of hand saws to pick from.

Western Rip Saws

An obvious choice is a big old Western rip saw.
When it comes to ripping then as a general rule the bigger and rougher the better. They tear through the wood at a good old rate but burn out will come fast. I’d say they’re also the easiest saws to learn how to sharpen with.
A shorter finer backless saw will be much more useful throughout your work though than something that’s fully dedicated, and you can even consider this hardpoint option if you want something low cost that’ll just about do the job straight off the shelf.

My Favourite Hard Point Saw

You’ll be able to see how well this Irwin saw cuts in the video (I have no affiliation).
It’s only 22″ in length and yet I’ve often grabbed it for making thick rips.
The unique thing about this particular hardpoint is that it’s well suited for ripping; it’s the only one I’ve found that is.

Of course if you have the budget for a nice new re-sharpenable saw, or the time to fettle an old one then I’m not discouraging you. Just be mindful of the extra learning curve if sawing and sharpening are new to you.
New skills such as saw fettling take time. Bear that in mind if you’re just wanting to crack on.

Japanese Pull Saws

In many ways Japanese saws are the opposite of a big coarse western rip saw.
They’re extremely thin in comparison and about half the length.

In general I find Japanese saws to cut extremely fast.
However when it comes to through ripping of think material they’re much slower. This is partly because as a western woodworker we’re probably just using a big Ryoba (double edged), as something more specialised may be difficult to source.

But still, the slower inch per minute time can be made up if there’s a lot to cut as I find sawing with these falls into much more of a rhythm and is something I can maintain for a good long while.

Western rip saws can feel a bit like grunt work powering through a cut, whereas Japanese saws are much more about finding that rhythm (think the tortoise and the hare). Sawing with these can almost feel therapeutic.

Something worth noting here though is that these saws respond better if used as intended. Don’t go at it with a westerner’s stance and approach.

Frame Saws

Though they tend to be seen a little less than the other two options, frame saws are actually one of my favourite choices.
If I had no bandsaw and was frequently finding myself with lots of thick rip cuts to make then I would invest some time into dabbling with these more.
I’ve only ever worked with frames that I’ve made myself (which can also make them a very cost effect option) but there are blades with all manner of teeth configurations for you to choose from.
This blade is actually a Japanese tooth pattern that works best on the push.

These saws cut very fast. And if you get into the right position they’re easy to find a good rhythm. They are very different from conventional saws so expect a bit of a learning curve while you get used to them.

Repurposing a bandsaw blade is another great route to try with these saws. You’d have full ability to set them up just how you need that way.

I can’t tell you that hefty, thick rip cutting is ever going to be a breeze, but at least there are plenty of options to go at.

If you’d like a more complete overview of the basic hand tools I’d recommend, then have a read of our guide for your getting started tool kit.

Woodworking can be a rewarding and satisfying hobby, and one way to start is by working with live edge wood slabs. In this blog post, we’ll provide a guide to live edge DIY , offering tips and resources for those who are just getting into woodworking.

Live edge wood is wood that has been cut from a tree in a way that preserves the natural edge of the wood, including the bark and irregularities in the shape of the tree. This creates a unique, natural look that can be used for a variety of DIY projects.

To get started with live edge DIY, you’ll need a few basic tools:

Circular saw or jigsaw: A circular saw or jigsaw is necessary for cutting the live edge wood to the desired size and shape. You can also use other types of saws such as table saws or chop saws if you have them available to you.

Sander or hand planer: A belt or rotary sander or hand planer can be used to smooth out the rough edges and surfaces of the live edge wood.

Clamps: Clamps are necessary for securing the live edge wood to a work surface during cutting and sanding. Clamps can also be helpful if you need to glue any pieces together.

Safety gear: Safety gear, including safety glasses and a dust mask, should be worn at all times when working with power tools and wood. Hearing protection is also a great idea if you are working with loud equipment like power tools for your DIY project.