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Occasionally, you’ll need to cut the bottom of a door to ensure flooring will glide smoothly underneath it. For this tricky job, you’ll need an undercut saw.
But what is an undercut saw, and do you really need to add it to your tools and gear collection?
What type do you need? Is it really worth spending more on an electric version? And what features should you be looking for?
We’ll look at all of these questions, as well as giving you our top 6 recommendations for both hand and electric undercut saws. But first, let’s look at our top picks compared to each other in terms of features and price.
At a Glance: 6 of the Best Undercut Saws
| Model | Electric or Hand Saw | Blade Type | Speed | Price |
| Crain 825 Heavy-Duty Undercut Saw | Electric | Masonry and Carbide | 6,500 RPM | $$$ |
| Kraft Tool FC518 Undercut Hand Saw | Hand | Steel | N/A | $ |
| Roberts 10-46 Super Six Jamb Saw | Electric | Carbide | 7,000 RPM | $$ |
| Crain 575 Multi Undercut Saw | Electric | Carbide | 11,000 RPM | $$$$$ |
| Rockwell RK5132K Multi-Tool | Electric | Steel | 11,000 – 22,000 | $$ |
| Roberts 10-56 Longneck Plus Jamb Saw | Electric | Carbide and Masonry | 7,500 | $$$ |
What is an Undercut Saw?
An undercut saw (or a jamb saw) is used in construction and woodworking. It looks similar to a circular saw, but it is designed with a specific purpose. For example, an undercut saw can trim around a door jamb so that flooring will fit nicely under the door. It can be used parallel to the floor, making it really easy to use even in very tight spaces.
It is a flat, circular saw (if using an electric version) with a strong, stable base for cutting. It’s not a hugely versatile tool, but it’s the only tool for the job of trimming the bottom of a door (before the invention of the undercut saw, this was a really difficult job to do). You can use it as a general cutting tool to undercut other items (it works particularly well on corners and on fireplaces), but its main purpose is as a door jamb saw.
If you want something more versatile, you could go for an oscillating multi-tool instead. These tools come with several attachments to do different types of jobs, including an undercut saw attachment.
What to Look for in an Undercut Saw
There are a few things to look for in an undercut saw:
Electric or Hand Saw
There are two basic types of undercut saw.
Electric undercut saws are, understandably, more expensive. However, they are powerful and easier to use than a hand saw, and they give professional, consistent results. If you only need to trim a couple of door jambs, you may want to use a hand saw, but the job is easier with an electric saw.
Hand saws have the advantage of being smaller and cheaper but involve more effort to use. However, they’re more portable, too, and you don’t have to worry about needing a power source or batteries to use them.
Settings
Electric undercut saws can be set to the height that you require for the job. You can lock the blade into place, holding it into place, so you get a consistent result and avoid damaging the surrounding area. You will see height markings on the side of the saw, allowing you to set it into the right position.
Blades
Typically, you will find two types of blades: carbide blades and masonry blades. Carbide blades can cut wood and have the advantage of retaining their sharp cutting edge for longer. Carbides can cope with high temperatures that may occur at high cutting speeds and are pretty durable too.
Masonry blades are used for trimming ceramic, brick, stone, and so on – these are super tough blades designed to cut through hard surfaces.
Some blades come with both, so you can swap them out for different jobs.
Motor Power
The stronger the motor, the more powerful your undercut saw will be. Power is measured in amps, with undercut saws ranging from 3.5 through to 8.
Power Source
If you’ve chosen to go for an electric model, you’ll have to consider the power source. Cordless tools are ideal for easy transportation, and you won’t have to worry about the cord getting in the way. However, these run on rechargeable batteries, which can run out and will require charging up again. They also tend to be less powerful than corded versions.
Corder tools are more powerful, and you won’t have to worry about charging batteries. They have the disadvantage of having a cord, which can sometimes get in the way.
Speed
The blade speed is measured in RPM (rotations per minute). The higher the number, the faster it will spin. Speeds vary, from 5,000-20,000 RPM. Some tools (like oscillating multitools) allow you to choose the best speed for the job. A lower speed has some advantages – like lower dust spreading and less chance of the tool overheating. Higher speeds are better for dealing with tougher materials.
Safety
Undercut saws should have some safety features built-in. For example, you may see a safety lock feature, which means you won’t be able to switch it on if the blades are not clicked into place properly.
Dust Management
Any time you use a powerful tool to cut materials, you will have to deal with excess dust. Dust can be a problem for a few reasons: it can be bad for your health to breathe in a lot of dust, and it can also get into the mechanism of your tool, which can cause it to stop working. Some tools come with a dust bag or a port to attach your own, which helps collect the dust to be emptied safely.
Noise
Any power tool will involve a bit of noise, so this is something to be aware of. If your undercut saw is loud, you should invest in a pair of ear defenders to protect your hearing.
Extra Features
You might find some extra features on undercut saws. For example, some DeWalt tools come with an LED light to illuminate dark work surfaces.
You should also look for an undercut saw with a hard carrying case to protect it, as well as a wrench to easily swap out the blades.
Warranty
Your undercut saw may come with a warranty. Warranties range from 1 year through to 3 years or more.
6 Best Undercut Saws
Let’s take a look at 6 of the best undercut saws out there.
1. Crain 825 Heavy-Duty Undercut Saw – Best for Tough Jobs
Key Specs
- Electric or Hand Saw: Electric
- Blade Type: Masonry and Carbide
- Power Source: Corded
- Amps: 8.15
- Speed: 6,500 RPM
- Warranty: Not Stated
The Crain 825 Heavy-Duty Undercut Saw is ideal for tough jobs. The 8.5 amp motor is strong enough to deal with wood and ceramic and brick, and although it has a lower RPM than some multi-tools on this list, it’s fast enough to deal with doors with ease.
It has both masonry and carbide blades and includes a wrench to swap them easily. The blades are high-quality and can be removed and sharpened.
It has a dust control port, which you can attach to a dust bag if you own one. It’s also purposefully designed with a slightly lower RPM than a multitool, which means it throws less dust as it goes.
It has a threaded rod height adjustment, meaning you can set the width before you go, locking the blade into the correct position.
It also comes with a carrying case. The downside is that it doesn’t really have any extra features – it’s a simple tool, but it does the job well.
Pros
- Tough enough to deal with ceramic and brick as well as wood
- Includes dust control port
- Blades can easily be swapped out
- Includes carrying case
Cons
- It doesn’t have any extra features
2. Kraft Tool FC518 Undercut Hand Saw – Best Hand Saw
Key Specs
- Electric or Hand Saw: Hand
- Blade Type: Steel
- Power Source: N/A
- Amps: N/A
- Speed: N/A
- Warranty: None
The Kraft Tool FC518 Undercut Hand Saw is ideal if you want a durable, tough little saw that can do the job very well.
It’s made from heavy-duty steel, which can be sharpened – so while it’s cheap to buy in comparison to an electric undercut saw, it should last for a long time. You can also replace the blade, which is great. The handle is nice and strong, and it’s pretty easy to swap the blade for a new one.
As this is a hand saw, there’s not much to talk about in terms of extra features. It would be nice if it came with a protective case, but it doesn’t, which is a shame. Also, the teeth are very sharp, so it would be better if it came with a case to store it in.
Pros
- Tough, durable hand saw
- The blade can be swapped out if needed
Cons
- It doesn’t come with a storage case
3. Roberts 10-46 Super Six Jamb Saw – Best Value
Key Specs
- Electric or Hand Saw: Electric
- Blade Type: Carbide
- Power Source: Corded
- Amps: 5
- Speed: 7,000 RPM
- Warranty: 1 Year
The Roberts 10-46 Super Six Jamb Saw is great value for an electric undercut saw. It may not be as powerful as some other tools on this list in terms of amps, but it’s strong enough to deal with wood.
It has one blade type – carbide – and the blades can be taken out and sharpened. This is pretty easy to do.
It has an adjustable cutting depth guide to stop you from damaging your floor or baseboards when using it.
It doesn’t come with much in the way of extras, but it does come with a molded carry case to protect it. So if you’re looking for something really simple and good value for money, this is the one to go for.
Pros
- Good value
- Blades can be sharpened
- Includes molded carry case
Cons
- It doesn’t come with any extras
4. Crain 575 Multi Undercut Saw – Good All-Rounder
Key Specs
- Electric or Hand Saw: Electric
- Blade Type: Carbide
- Power Source: Corded
- Amps: 6.2 Amps
- Speed: 11,000 RPM
- Warranty: Not stated
The Crain 575 Multi Undercut Saw is a tough, strong tool. It has 6.2 amps of power, which is ideal for trimming doors, and the max speed of 11,000 RPM means it works quickly.
It has a carbide blade, which means you won’t be able to use it to cut tougher materials like brick or ceramic. This means that, on the whole, it’s a fairly pricey tool. However, if you are a professional and you often work with corners or doors, you may think it’s worth the investment, as it’s very durable. In addition, the blades can be sharpened or replaced easily.
It has a cutting depth guide, allowing you to lock the blades into place to improve accuracy.
It doesn’t have many extra features, but it has a handy carry case and a spanner wrench to swap the blades.
Pros
- Durable
- Ideal for professionals
- Includes carry case
Cons
- A little pricey
5. Rockwell RK5132K Multi-Tool – Best Multi-Tool
Key Specs
- Electric or Hand Saw: Electric
- Blade Type: Steel
- Power Source: Corded
- Amps: 3.5 Amps
- Speed: 11,000 – 22,000 RPM
- Warranty: 3 Years
The Rockwell RK5132K Multi-Tool is a great choice if you want something versatile. Not just used as an undercut saw, you can use the multi-tool for lots of different jobs depending on the parts you buy to go with it.
It includes a variety of steel blades, which are strong and durable. You can also buy other blades to fit this saw. While it’s not designed just as an undercut tool, so it lacks some special features (for example, it doesn’t have a cutting depth guide), it may be worth it if you’re looking for a general cutting tool for a good price.
It includes several blades, 26 sanding pads, and the speed can be adjusted to suit the task at hand, ranging from 11,000 – 22,000.
Pros
- Versatile
- Strong, durable blades
- Includes a lot of accessories
Cons
- It doesn’t have a cutting depth guide
6. Roberts 10-56 Longneck Plus Jamb Saw – Best Industrial-Grade Undercut Saw
Key Specs
- Electric or Hand Saw: Electric
- Blade Type: Carbide, masonry
- Power Source: Corded
- Amps: 9.6 Amps
- Speed: 7,500 RPM
- Warranty: Not Stated
The Roberts 10-56 Longneck Plus Jamb Saw is an industrial-grade undercut saw with a super powerful motor.
It has both carbide and masonry blades included, both sturdy and durable and can be easily swapped out when needed. It’s powerful enough to deal with some tough materials using the masonry blade, so you can use it on fireplaces too.
It has an adjustable cutting guide to keep you from accidentally cutting into the surrounding area, which is great, and it also has a dust collection port that you can use with a dust collection bag.
It also comes with a custom-molded case to protect it between uses, but it lacks any extra features.
Pros
- Very strong
- Includes both carbide and masonry blades
- Dust collection port included
Cons
- It doesn’t have much in the way of extra features
Frequently Asked Questions
Before we talk about our favorite undercut saw, let’s take a look at some frequently asked questions:
Question: How can I stay safe when using an undercut saw?
Answer: There are a few things to consider when using any power tools:
• Eyes – protect your eyes from dust and debris using safety glasses
• Ears – using power tools can damage your hearing over time. Using ear defenders can help to protect your ears
• Cables – make sure that any power cables are tucked safely out of the way
• Dust – use a dust collection bag to help keep dust under control, and consider using a face mask to prevent you from breathing it in
Question: Is it worth buying an undercut saw?
Answer: It depends on how much you think you’ll use it. An undercut saw is a fairly specific tool, so you may not get much use out of it if you just want to do some DIY around the house. In that case, we’d recommend going for a multi-tool instead. If you’re a professional, you might want to consider adding an undercut saw to your tool kit, as it does the job quickly and easily.
Question: Can I use a regular hand saw instead of an undercut saw?
Answer: Not really. It’s difficult to use a regular saw, as it’s such a tough angle to reach properly. Using a regular saw will end up with some pretty uneven cuts, so it’s not worth taking the risk – if you don’t want to invest in an electric one, an undercut hand saw will be a better choice, and they’re pretty low in price.
Question: Can I use an angle grinder as an undercut saw?
Answer: Although angle grinders and undercut saws look very similar, the blades are very different. An angle grinder has a smooth blade, but an undercut saw has rough, jagged teeth, allowing them to cut through wood easily.
Our Final Thoughts: Which is the Best Undercut Saw?
If we had to pick one undercut saw, we’d probably go for the Roberts 10-46 Super Six Jamb Saw. It’s great value for money, and while it lacks extra features, it does make quick and easy work of dealing with door jambs.
A multitool could be a good investment if you want to have something a bit more versatile, in which case you could look at the Rockwell RK5132K Multi-Tool. On the other hand, if you just want something cheap to deal with the odd door jamb issue, we’d recommend the Kraft Tool FC518 Undercut Hand Saw. It’s sharp, durable, and good value for money.
We hope this has helped you to find the best undercut saw! If you’re getting into woodworking, check out our guide to the best felling ax and our Husqvarna 450 chainsaw review if you’re looking for more gear recommendations.