Investing in the best benchtop jointer that you can afford, is the entry point to any well-functioning shop. Woodworking is all about joining boards. This may seem like an obvious concept, not deserving of much attention. In reality, preparing boards for joining is the most essential step in creating furniture, cabinets, or any type of wood joinery.
If your boards are not perfectly flat and square, you will never obtain perfect results. This is why a jointer is the first step in board preparation. Ideally, every board entering your woodworking shop should be run across a jointer until it is flat, and the edges are square. This makes cutting and thicknessing so much easier as you move along the process of creating quality crafted projects.
At this point, you may be asking what’s the difference between a jointer and a planer? They seem to do pretty much the same thing. I will be answering most of the frequently asked questions about jointers and planers after reviewing the best benchtop jointers for the money.
Though, before the review and all the other useful information to come, I think it’s important to understand the basics with regards to jointers vs planers. It will make it much easier (especially for beginners) to grasp why a jointer is so important and what to consider when buying the best benchtop jointer for your shop.
Jointer vs Planer
A jointer should always be the first step in processing wood for any type of project. You can pay for boards that have been flattened and squared, eliminating the need for a jointer. However, as you take on more projects, buying wood that has been flattened for you becomes exorbitantly expensive. It is worthwhile to buy a jointer in the long run.
You may also want to invest in a planer to speed things up. First of all you need to know the difference between a jointer and a planer.
As I mentioned, a jointer is used to flatten boards. This is its only purpose, an important one. There really is no such thing as a perfectly flat board coming directly from the lumber yard. At least, it is incredibly rare to find raw, unprocessed wood that is flat enough to work with. Bows, warping, and twisting is just a natural tendency of wood.
A jointer consists of two parallel beds, with a cutter between these beds. It will have a fence which allows you to square two opposing sides at 90° or create an angle for specific joins. As you run the board across the cutter it will shave away small amounts of wood. The cutter will only remove wood that comes into contact with the blades. If the surface is uneven, like a curved board, it will remove the wood that is on the outer section of the curve. Thereby flattening out the curve.
Depending on how uneven the wood is, it may take several passes to flatten a board. With each pass, the higher areas are gradually removed until the entire surface is even and perfectly flat. You can then run this flat surface against the fence to square up the perpendicular edge.
A planer is similar, as it too has two parallel tables with a cutter in between. It’s understandable why many are confused by the difference between these machines. Using a planer vs a jointer is about the intended outcome. A planer is used to obtain uniform thickness and a jointer creates a flat surface.
In addition to the tables, a planer has rollers that press down on the wood. You adjust the rollers in relation to the tables to obtain the exact thickness required. The rollers apply pressure on the wood, forcing it against the table and cutters. If the wood fed into a planer is not perfectly flat, the rollers will simply continue to cut along the existing curve of the wood. The wood will be a uniform thickness but will not be flattened.
It is therefore essential to only pass flat boards through a planer. This means using a jointer before cutting it to the correct thickness using a planer.
There will be a lot more advice and tips on this topic after the review. I’ll also provide a guide on using a planer for novices.
Reviews : Best Benchtop Jointer
You will find many reviews suggesting great benchtop jointers for a home or commercial shop. Since most professionals require something larger, benchtop jointer reviews are generally aimed at the home user. Though many mid-sized professional shops may find a top-quality benchtop machine to be more practical.
Some professional shops will have several jointers to increase productivity. A benchtop machine will allow for smaller boards to processed while the larger jointers are occupied with wider or longer boards.
For this reason, we cannot say that one size fits all when buying a benchtop jointer. This is why we’re providing a review of the best benchtop jointer for the money.
A beginner is probably going to be more interested in the best budget benchtop jointer. Whereas the more seasoned hobbyist may be interested in something more accomplished and will be prepared to pay more for this. The master craftsman, whether amateur or professional, is probably going to want the best there is, preferring professional grade machines that will, inevitably, be the most expensive.
Regardless of your needs or budget, you want the reassurance that you’re spending your hard-earned cash wisely. This is what this review is all about. By providing you with all there is to know about each of the products, you can decide which is the best for you.
Half the job has already been accomplished, as every benchtop jointer chosen for this review has already been shortlisted as being the best of its kind. They all differ, to some extent, but they have made the grade as being genuine value for money. We haven’t chosen the cheapest, or most expensive benchtop jointers for this review. We’ve looked for outstanding qualities vs price. This way you know exactly what you’re getting for your money.
Note : Product Images Coming Within the Next 24 hours. Thanks for your patience.
Review : Porter-Cable / 6” / PC160JT
Since we’re discussing the best benchtop jointer for the money, it seems fitting to get the ball rolling with the reasonably priced Porter Cable PC160JT (6” model). The price is great. General performance and quality is much higher than one would expect in this price range. This boils down to the essence of this review as the Porter Cable PC160JT is undeniably one of the best options for what you’re paying.
The size is pretty standard for a benchtop jointer, bed width is 6” with a length of 30”. I like the solid feel of the infeed and outfeed tables, really thick metal that has been machined to a wonderfully smooth surface. This makes it a pleasure to use.
There is no shortage of power for a jointer of this size. The 1.4 HP electric motor drives the 2-blade cutter at a variable speed from 6,000 to 11,000 RPM. This translates into 12,000 to 22,000 cuts per minute. It does a great job for a conventional 2-knife cutter head. Obviously not as good as a spiral cutter. I tried to find a spiral cutter conversion for this model but was unable to. That’s a little disappointing as I think many would want this upgrade. At the price, I think the standard cutting head is perfectly acceptable.
Setting up the Porter Cable PC160JT for the first time doesn’t take much effort. You have to install the fence, that’s no big deal. Take some care to check that the fence is square before using the jointer for the first time. It may take a little effort before you get the fence properly aligned for perfectly square cutting. I should also mention that the fence does not feel quite as solid as the rest of the machine. There is some horizontal movement if you press hard against the fence. Again, not a deal-breaker at the price. You just need to take care when pressing boards against the fence. Too much pressure and it will flex, causing the board to tilt at a slight angle. If you’re aware of this, it really isn’t a hassle.
The Porter Cable PC160JT has a built-in cutter head lock that is truly simple in its design. This makes it really easy to use and, without any complicated components, ultimately durable. An adjustment knob, with easy to read markings, makes it quick and simple to set your infeed table height for accurate depth of cut.
The machine weighs 35-pounds which provides a great balance between portability and stability. It’s lightweight enough to be carried with ease yet stands quite firmly on your workbench. Rubber feet help eliminate vibration and unwanted movement. It also has a dust port, so your workshop won’t be coated in sawdust. The on/off switch seems to be good quality but is not a paddle style safety switch. The plastic dials for adjusting blade speed and cutting depth are also great quality for a jointer at this price.
Another thing to be aware of; be careful when tightening the cutter head jack screws. The screws are made of a harder metal than the body of the machine into which they fasten. It is quite easy to inadvertently overtighten the jack screws which will cut into the metal body. This won’t cause immediate damage but may become a problem in the long run.
I consider the Porter Cable PC160JT one of the best benchtop jointers for a home shop. It is value for money all the way. Being a cut above most of the cheaper options, one could even consider this as an entry level professional machine. As part of the Stanley Black & Decker group, Porter Cable is an established American brand that comes with some weight behind the name. A 3-year warranty, for a reasonably cheap benchtop jointer, is way better than I would have expected. All-around excellent value for money.
Review : Craftsman CMEW020
Since Craftsman don’t actually manufacture their own tools (they are essentially rebranded models from trusted brands), I’m always curious as to who actually makes Craftsman tools. They use a variety of manufacturers, depending on which one offers the best deal. I always try and guess who makes the original machine upon which the Craftsman tool is based. In this case I’m almost sure that the Craftsman CMEW020 is a slightly modified version of the Porter Cable PC160JT, that was reviewed above.
Being practically the same machine, possibly cheaper (depending on where you buy), the Craftsman CMEW020 can be considered one of the best value benchtop jointers for a home shop. Some may even consider it as an economy option for a professional shop.
There are a few cosmetic differences between the Craftsman CMEW020 and the Porter Cable original. The Craftsman benchtop jointer is red, whereas the Porter Cable is gray. The adjustment dials look a little different but perform exactly the same function. I like that Craftsman decided to replace the more conventional power switch with a professional grade safety paddle switch.
In every aspect of it’s basic design, you can’t tell the difference between the Craftsman CMEW020 and the Porter Cable PC160JT. It has the same table (6” X 30”). The 10A motor appears to be exactly the same too, running at a variable speed of 6,000 to 11,000 RPM. Since the Craftsman jointer is also equipped with a standard 2-blade cutter, blade speed is the same too; 12,000 to 22,000 cuts per minute.
The lightweight fence, being the same as the Porter Cable model, has the same issue. It’s not as solid as many others and will bend on its support mounts if you press too hard against it. As with all the comparable components, the Craftsman jointer has a simple, wonderfully functional cutter head lock and easy to use depth adjustment with clear markings.
The Craftsman CMEW020 weighs 35-pounds and has the same great rubber feet, making this a secure machine that stands firmly on your work bench. The dust port does a fantastic job, with just about no visible sawdust left behind.
It’s quite ironic that Craftsman tools and power equipment are often cheaper than the same model with the original branding. If you shop around, you will probably find this to be the case when comparing prices between the Craftsman CMEW020 and Porter Cable PC160JT. The obvious choice would be the cheaper of the two, since they are practically identical. The only real difference being an upgraded on/off switch on the Craftsman model, making it a slightly better option. The warranty is the same (3-years), probably both serviced by Porter Cable. This means you have the same peace of mind, regardless of which brand you choose.
Review : Shop Fox W1876
Shop Fox equipment usually has me saying wow. This is because I’m always pleasantly surprised at how much you’re getting for your money. The Shop Fox W1876 won’t be out of place in a professional shop yet doesn’t cost much more than your average light-duty home shop jointer. This is a heavy duty benchtop jointer without the heavy-duty price tag. You’ve got to love that, especially if you’re serious about getting the best benchtop jointer for the money.
The Shop Fox W1876 is no ordinary 6” benchtop jointer. If we start out by looking at how much this machines weighs, this becomes quite evident. At almost 43-pounds, the Shop Fox W1876 is noticeably heavier than many others in its class. In my opinion, that’s a good thing. It’s a little heavy to carry but still portable enough. More importantly, this weights indicates heavy-duty construction, and it won’t move about easily as you work. Something I greatly appreciate.
One of the first signs that this is not a cheaply made product is the 12 carbide insert spiral style cutter head. It uses a 10A 1.5 HP motor providing 12,000 RPM which is fantastically smooth with this type of cutter and highly efficient.
When I took a look at the ultra-thick 6” X 30” bed, my admiration for this jointer grew even greater. It’s as smooth as glass and clearly top-quality. The Fence with a tilting center mount is equally impressive and can be easily adjusted to place boards at an angle.
Setting up the machine is a little complicated and the instructions aren’t all that helpful. A bit of shame to be let down with this seemingly insignificant detail, when the machine itself is so great. Once you eventually have the Shop Fox jointer up and running, the rest is a breeze.
It has a large safety on/off switch and adjustments that are super easy to use. I like the depth indicator, which is not only supremely accurate, but shows both inches and millimeter settings. No metric conversions needed. This is a single speed jointer so there’s no speed adjustment dial. It has a well-designed dust extraction system, with a 2½” port.
The Shop Fox W1876 is uncompromised value for money. It’s inexpensive rather than being cheap. By this I mean that it is a high-quality industrial grade machine as opposed to cheap junk. At this price it offers much more than any other costing about the same. Genuine good value, as I see it.
Review : RIKON 20-600H
The Rikon 20-600H is another good value industrial grade benchtop jointer. In my opinion, a worthy rival to the impeccable Shop Fox model reviewed above. There are several similarities, making it just about impossible to say which one is the better option. Perhaps only the price might be a deciding factor.
Establishing this as a tool that professionals will relish, the Rikon 20-600H has a top notch helical cutter, similar to the one fitted to the Shop Fox jointer. I can’t say with any certainty if one is better than the other, they look quite similar. The difference being that the Rikon cutter inserts are made from High Speed Steel (HSS) as opposed to carbide used for the Fox Shop. I don’t have much preference either way, both are great. The cutter speed is the same at 12,000 RPM.
Power to the cutter is supplied by a superb 10A motor, with 20,000 RPM speed. The gearing ratio to the cutter provides a good deal of extra torque which should be beneficial when working with hard wood.
I’m hugely impressed with the machined aluminum bed. I believe that it should remain perfectly flat for a lifetime and is as durable as they come. You adjust the bed height in the normal manner, with a dial on the front panel. The scale markings make it really easy to obtain accurate settings. The Rikon 20-600H has an industrial safety on/off switch.
The fence is in keeping with the overall high-quality professional standard. It is made from rigid aluminum with the sturdy center mount. Simple locking handles make it easy to shift the fence into position and adjust the angle from 45° to 135°.
Because of the extensive use of lightweight aluminum, the Rikon 20-600H is not as heavy as one would expect an industrial grade benchtop jointer to be. I think 36-pounds is very reasonable for a high-quality machine like this. It has a genuinely solid feel and stands on strong rubber feet, reducing vibration. Dust extraction is made possible using a 2½” port.
I’ve read a few reviews claiming that the fence is junk, flimsy and difficult to align. Perhaps I’m missing something here, but I don’t see it. Like most benchtop planers, the fence is not solid, it is made from aluminum plates that have been reinforced. Compared to the really cheap models, I think this fence is more than up to the task for which it has been designed. The lightweight feel is deceptive as the smart design makes it very ridged and reliable.
It might be a coin toss, deciding between the Shop Fox 6” benchtop jointer and the Rikon 20-600H. I really can’t decide. These are both great brands, and Rikon offer an amazing 5-year warranty. I don’t believe that a warranty is sign of how long a tool will actually last, but a warranty lasting 5-years does give one a good deal of confidence.
Review : WEN JT6561
WEN equipment varies greatly. The brand is known for manufacturing some of the most affordable tools that are, for their price, truly great. Though I usually recommend WEN machines as entry level options for beginners and DIYers who aren’t going to expect it to work as hard as one would in a professional environment. The WEN JT6561 defies all these expectations. This heavy, all-cast iron benchtop jointer gives one the impression that it is built to last forever. It weighs a really hefty 63-pounds.
Most of the other jointers in this review are substantially lighter than this WEN model. The reason being that the heavier components, like the bed and fence are made from aluminum. This is great for portability, but aluminum is expensive and not as good as cast iron in its ability to absorb vibration. The WEN JT6561 has a thick cast iron bed and a cast iron fence. The complaints that some users have expressed about the lightweight aluminum fence on the other jointers, won’t apply to this WEN model. It’s as solid as a rock from the ground up. I like this a lot and it’s indicative that the WEN JT6561 is not one of their cheap products intended only for light duty work.
Despite displaying so many industrial grade qualities, this not at all an expensive benchtop jointer. True to the WEN reputation, it is downright excellent value for money. If you don’t mind the extra weight, it may well be the best value jointer of all the models reviewed here.
The bed width is 6¼”, providing a fraction more width capacity than the others. Table length is fairly average for a jointer in this class – 28⁵⁄₈”. The 2-blade cutter is about the only indication of that this is an inexpensive tool. Everything else is way above what one expects at this price. Though, the absence of a depth gauge is another thing that some have commented on. You actually have to measure the distance between the blade and the infeed table manually to obtain an accurate depth of cut. If you’re the kind of guy who does this by feel, turning the adjustment dial by a half-turn and seeing how it goes, this won’t be a problem.
Setting up the WEN JT6561, straight out the box, takes some time. Most people seem to go through a bit of trial and error getting all the screws and handles just right when installing the fence. The user manual is quite helpful but there are a lot of components that have to be installed correctly. If you’re not the best at following diagrams and instructions, there are a bunch of really helpful videos on You Tube that can be of great help in this regard. [https://www.youtube.com/watch?v=dGF9eCHJCiM] Part of the reason for the complicated fence setup is the easy to use fence adjustment, with 45° bevel. There are quite a lot a of springs and handles that may be complicated to figure out, but once assembled, make it a real pleasure to use. Like the rest of the machine, all these components are heavy duty, made from cast iron.
After your rather time consuming unboxing it should be plain sailing from here on. The WEN JT6561 has an industrial style safety power switch. Flip it to the on position and the 10A electric motor springs to life, providing 20,000 cuts per minute. An adjustable 2½” chute takes care of dust extraction.
Quite a remarkable benchtop jointer for such a reasonable price. I absolutely love the solid, never say die, design and build quality. The WEN JT6561 may not be the easiest to carry, it is as tough as they get, and I really like this for a tool that is one of the cheaper options. A far cry from the light-duty home shop WEN tools that we normally expect from the brand.
Review : WEN 6559
In contrast to the WEN JT6561 (reviewed above), the WEN 6559 is most definitely an entry level benchtop jointer. At around $250 – $270, depending on where you buy it, no one would expect anything great for a jointer at a price this low. This really low price makes the WEN 6559 an incredibly attractive option for occasional or beginner woodworkers. Taken in this context, it is a pretty remarkable machine. I, along with many others, rate this as the best cheap benchtop jointer.
Without very high expectations, I set about reviewing the WEN 6559 with some level of trepidation. A jointer this cheap can’t possibly be up to the task. Because of my initial misgivings, I ended up being pleasantly surprised. It is cheap, and certainly not a perfect machine. At the same, it is far from being junk.
First off, the bad news. The fence really isn’t that great. Compared to the cast iron fence used for the more expensive WEN JT6561, it is a real disappointment. The lightweight aluminum fence fits quite easily to the machine, it’s not as complicated to set up and has the same ease of use when setting the jointer up for a bevel cut up to 45°. So far, so good.
As you start to use the Little WEN jointer, things become a little frustrating if you are an abject perfectionist. You probably won’t get a perfectly square cut or obtain any angle with exacting precision. There is some movement on the fence, which increases if you apply any type of force against it. Even with a gentle hand, you may still end up with an angle that is about 1° out, possibly more. For the casual or beginner carpenter this probably won’t be a big deal. I remember my first projects were never perfect, regardless of the tools that I used. If you’ve perfected your techniques and expect the very best precision, you won’t rate the WEN 6559 that highly.
The second issue would be the 2 blade cutter. It is great for softwood and leaves a wonderfully smooth surface on pine and similar materials. If you’re going to be working with maple, cherry, or similar hardwoods, the blades probably won’t hold up for very long.
Having pointed out these imperfections, I should justify all of this by saying any jointer at this price will have similar deficiencies. I wouldn’t expect the greatest results form a jointer costing well under 300 bucks. These machines will always be a little mediocre at best. If anything, the WEN 6559 is better than the average cheap jointer when considering power and accuracy.
Now for the good news. General build quality has exceeded my expectations by a mile. It has a solid heavy bed with a good width of 6¼” and is 28½” long. Although the cutter head is not top-grade, the electric motor is about as good as any jointer of this size. The 10A motor allows for a maximum speed of 20,000 cuts per minute. This means that, even though the blades aren’t the toughest, it is perfect for softwood.
Depth adjustment is super easy, using a knob on the front panel. The depth gauge position put a smile on my face, it’s really cleverly positioned on the top, parallel to the bed. Most are on the front of the machine close to the adjustment dial, meaning that you have to bend, or step back a little to check your depth of cut. When using the WEN 6559, you only have to glance down at the table. Though, like the fence, the table depth doesn’t always remain exactly where you set it.
The machine weighs a perfectly respectable 36.4 pounds. Easy to carry and it can be bolted to your workbench to keep it from moving about. The WEN 6559 has a great dust extraction port (2½”) that can be adjusted for the most convenient angle.
I’m willing to forgive the WEN 6559 its little imperfections. This is not a high-end professional grade jointer. It is certainly not pretending to be one either. This little machine is a wonderful beginner tool. It won’t set you back much, and you can always upgrade in few years as you hone your skills. A perfecter light-duty jointer at an amazing price.
Benchtop Jointers — Frequently asked questions
Having read our review of the best benchtop jointers for the money, I’m sure many of you have some questions you want answered. Buying, or using, your first jointer isn’t as easy as some may think.
To help newbies and intermediate users alike, I’ll be answering the most common questions associated with these machines. This will be followed by a guide on how to set up and use a jointer.
Q : Jointer vs Planer?
A: This question was answered in detail in the introduction to the article, so here’s the short answer. A jointer is used to flatten uneven boards, whereas a planer is used to obtain a uniform thickness.
Q : What is a jointer?
A : A jointer is a benchtop or free-standing machine that consists of an infeed table, outfeed table, and a fence. Between the tables (or bed) a rotating cutter removes small amounts of material, usually up to about ⅛” as the board is passed over it.
By adjusting the height of the infeed table relative to the cutter, the user is able to control how much material is removed with each pass. The fence keeps the board perpendicular to the bench and can adjusted (on some models) to cut the board at an angle, allowing for bevel joins.
Q : What is a parallelogram jointer?
A: Traditionally, jointers use a dovetail joint to align the infeed and outfeed tables. This means that the tables slide along a wedge that keeps them parallel. However, the wedges are not too reliable. As you adjust the depth, by raising or lowering the infeed table, it may slide to the left or right. The table may also tilt to one side. This causes the two tables to move out of alignment and will affect the angle of the cut. Because of this unreliability issue, you regularly have to check if the tables are parallel. If the tables are not parallel, you will need to make corrections which is time consuming and laborious. It usually requires inserting shims on the lower side to raise it to the same height as the other.
To circumvent this unwanted hassle, some jointers (like the Grizzly G0857) use a parallelogram to keep the tables parallel. Instead of tables sliding along a dovetail wedge, they are mounted to several parallel arms under the table. As you adjust the table height, it pivots on these arms, keeping it parallel at all times. Even if you press heavily down on the table, it will remain level and all sides will be at the same height.
Because there is no friction, as is the case when two wedges move against each other, there is no wear on the table adjustment mechanism. It remains level and parallel with repeated use.
Although Parallelogram jointers are more expensive, many prefer them for the hassle-free adjustment and durability.
Q: Which should you buy first – a jointer or planer?
A: Both jointers and planers are fairly expensive. If you’re starting out as a woodworker, it may not be possible to buy all the tools you need at once. Ideally, your shop should have both a jointer and a planer. Since many have to prioritize which comes first, here’s my advice.
I would recommend buying the planer first. Since you can buy boards that have already been flattened, you can use these instead of rough timber. Essentially, the jointer will save you money in the long term as you won’t need to pay extra for flattened boards. A planer ensures that you can cut these boards to a uniform thickness, it is the only woodworking machine that can do this accurately, without much effort or skill.
Q: What is the difference between a jointer and a planer?
A: A jointer has a flat bed with an infeed table and an outfeed table. Between the tables, a circular cutter spins and blades shave off small amounts of wood. It removes layers from an uneven surface until the board is perfectly flat.
A planer has the same infeed, outfeed, and blade setup as a jointer. In addition to this, it has a bulkhead above the table with rollers that press evenly down on the board. The head can be moved up or down, depending on the thickness of the board. It ensures that the board always remains parallel to the bed, it cannot lift at one end. This means that the thickness remains even. It prevents one side being thinner than the other.
How to use a Jointer —
Before using your jointer for the first time, it is essential to assemble it correctly and check that everything is as it should be. Start out by reading your instruction manual. Assembling the fence can be tricky and may require a few tries to get it just right.
Once you’ve successfully assembled the jointer ,you need to check that all surfaces are correctly aligned. If your fence has a bevel adjustment, set it to the 90° angle and check that it is square to the table. Check that the beds are aligned. This means measuring the distance between the left and right sides of the infeed and outfeed tables where they meet (either side of the cutter head).
If you find that the fence is not 100% perpendicular to the bed, or that one side of the table is misaligned to the corresponding edge, you will need to make adjustments to obtain a level and square relationship between all these components. Your user manual should provide instructions on how to do this. Sometimes, it may require some ingenuity, especially with cheap jointers. You may need to improvise spacers, using washers or shims to compensate for discrepancies between one side and its corresponding edge.
If you can’t find a solution, your dealership may be able to help.
Now that your jointer is setup and ready for use, it’s time to see how it functions. Always use a test piece to check that everything is working properly. You don’t want to waste valuable lumber before you know that the jointer is working properly.
Decide how much of the surface area you want to remove. In other words, your depth of cut. You adjust the cutting depth by moving the infeed table up or down. As you lower the table, in relation to the cutter, you will remove more wood with each pass. It is usually better to start off by removing only a small layer of wood from the surface, especially if you’re not yet familiar with the machine.
As you increase cutting depth, the motor and cutting blades require more power. If the wood is too dense, the motor may stop, causing the cutter head to jam. You may also damage the blades if you apply too much force on them. When in doubt, remove the desired amount over several passes. Generally, you get better smoother results by only removing thin layers at a time.
With your cutting depth set, place the board on the infeed table. Ensure that it is pressed firmly against the fence, keeping the piece square at all times. While you need to hold the board firmly, you should never apply too much force. Pushing hard against the fence, may cause it to tilt away from the bed, which will cause the workpiece to lift at the opposite end and your wood won’t be square.
The same principle applies when pressing down on the board as you slide it over the cutter head. You should only apply enough downward pressure to keep the board firmly in position, you don’t want it to move from side to side or lift away from the bed at one end. If you press down too hard, you may flatten the curve that trying to remove. When you remove this pressure, the board will spring back to its original curve. You won’t be flattening it.
Once you’ve flattened one side of the board, turn it 90° and repeat the same procedure to obtain a 90° (or bevel) angle. Once completed, check that both surfaces are flat and perpendicular to one another.