Flattening Workbenches and Wide Boards With A Router | The Router Sled

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The traditional method for flattening a workbench is to use hand planes and winding sticks. While some folks truly relish this labor of love, others prefer to delegate this grunt work to power tools. The power tool method is very similar to the action of a CNC machine. A router is placed inside a sled that rides along two parallel rails that are attached to the sides of the bench. The router sled is very easy to make from scrap 3/4″ plywood. The rails can be made from 2×6 construction-grade lumber. Cheap and simple!
Here are two options for router bits. They have the same specs (1 3/4″, 2-flute straight bits) but the Freud will save you a few bucks:
Amana -- 45453 - amzn.to/2AV03Uk
Freud -- 12-194 - amzn.to/2EAN38o
Perhaps one of the best parts about this jig is that you can re-use it for other things. Have an end grain cutting board that needs flattening, but you don't want to send it through your planer? Have an oddly-shaped natural edge slab that is just too large for your tools? Both situations can be handled with a setup like this. And if you plan on using it a lot, you can get as elaborate as you want with the design of the jig. The version I show you here is stripped down to the absolute basics.
This video is an excerpt from the recent Split-Top Roubo Workbench Guild Build. Join the Guild today to see the entire set of videos and build your own lifetime workbench!

[@charlesprescott4644]

These type of videos never get old. Thank you so much for help in this.

[@dennydenco]

Seriously, you are a very effective teacher. Speaking as a novice woodworker, I really appreciate how clearly you communicate and I find your videos very helpful. Keep up the great work.

[@Okie-Tom]

Very nice router sled. I use a similar setup to get everything square with the strings or wires. One difference I use that makes it easy to see when the two wires just kiss is this: instead of using plastic coated wires, I use uncoated wires. Then I use my little 12 volt battery charger with one lead hooked to one side of one of the rails. The other lead goes to the other sides rail wire but there I have a little 12 volt bulb holder with wire leads coming out of it hooked between the battery charger lead and the rail wire. Now when you tap the rail down, as soon as the two wires touch, the little bulb lights up. I have done this getting accuracy down to the thousandths of an inch. Tom

[@thomasarussellsr]

Tom heck of a solution.

[@maximedboisvert]

Tom Pretty neat trick there !! Thanks

[@BrainSlugs83]

Neat. Seems like you could do the same with a multimeter, and just listen for the auditory beep. :-)

[@chrisfroman2250]

Pardon my ignorance but couldn't you assure that the rails are parallel by simply using a level between the two sides? Is that just not accurate enough?

[@goldstandard3714]

Shim the "sacrificial" rails away from the work and they are no longer "sacrificial". Great video, Thank You

[@ericaugustus9435]

Marc - just did this project this morning. My dad built a maple bench top & ended up giving it to me. He had provided a written description of this process, but having the video made it very easy to understand & follow along. It ended up great! I think I routed about a 32nd at the best spot, and .52” at the worst. Thanks for such a great, informational video!

[@johnnykelly8582]

Every time I watch one of your videos, I am reminded of how much I suck. Just the way you drop in little reminders allows a somewhat newbie to understand what you are talking about. Doing the things you do is a completely different story. Thank you for taking the time to make these videos. It has helped me so much. Keep them coming. Johnny K

[@terrythomas9902]

Great video. Followed your technique for flattening my bench and it worked perfectly. For the first time in years I can use the bench as it was intended. Thanks!

[@yamahawfo]

This is the perfect solution for my situation. I do not have a designated woodworking bench and do everything on my plywood home built tablesaw/mitersaw cabinet. With no confidence in the flatness of my garage floor to support the rails level/parallel in order to router mill my first slab, your method of sacrificial rails clamped to the workbench (saw cabinet in my case) should be THE PERFECT solution!!! THANK YOU FOR SHARING! Your video was perfect in timing, amount of information and delivery also. Nice work!

[@mark.mahorney]

Thanks for the video, idea for slight improvement, add another narrower board between the rails and the table, attach them to the table or rails so they will be slightly above table top, then route right on over the edge of the table into the these boards. This would prevent possible chip out and you would have no edge clean up at the end.

[@fin1199]

that thought jumped out at me the instant he hit the rail with the router. great minds think alike, and so do we, lol

[@mattg6262]

But wouldn't the 2 x 6s accomplish the same thing if they are flush to the side of the workbench? It would be a taller surface that the bit would come I to but they would still be keeping the fibers intact at the edge of the bench I would think? Anyway it's a good suggestion.

[@hadean2]

Great instructional video! I'm going to use this method to flatten a half tree trunk for a sitting bench in the backyard. Chainsaw left a very uneven surface. Your explanation is clear and concise. I wish there were more videos of this quality on KZbin. Thank you so much for spending your time to do it.

[@allynhansen7398]

Thanks Bud, I recently inherited a woodwork bench from my Uncle but it's not flat. I did not know how to get it flat so I watched a good number of videos on how to do it but yours is by far the most simple and easy to follow method. Thank you very much. It means I will not have to travel to my cousins in order to use his planer and jointer once the table is flat.. Regards, Allyn Hansen New Zealand.

[@furtim1]

The length is fine, in my opinion. I am new to the tools and the craft. I just bought my first router (old Caftsman) at an estate sale for $10. I appreciate the explanations and demonstrations you presented. Thanks for taking the time to put this 22 minute video together!

[@brianmullaney2867]

Just wanted you to know I used your method and wound up with a dead flat surface. Flat as a pancake. I couldn't be happier. Thanks for the great video. Something I added that helped was stop blocks on either end of the bottom side of the sled. This kept the sled from sliding off the rails. I added a spacer between the rails and the bench top which let me route all the way to the edge. Final change was I used pre primed MDF from Home Depot for the rails. The primed surface is nice and slick for the sled and factory MDF edges are dead straight. Again great video, this method works folks.

[@davelee5605]

I am a Machinist/Engineer by trade [retired GM] Your techniques are impressive. Thx for your expertise. I am thoroughly impressed and hard to dazzle :-)

[@cpalmisciano]

This is the first time I came across using the flexible cords to align the rails properly. After seeing that, I became aware of the self inflicted twisting one can be making on any large board when using a sled router. Pure genius (you must be really good in geometry)!!

[@steveswoodworking2504]

I just used this method on my new Roubo workbench top. I was having a terrible time with the hand plane tearing out the wood. This method did the trick. I had a bit of anxiety when doing it, but it all worked great! I did glue on a couple of stop blocks on the bottom of the sled on each end, so it wouldn't accidentally fall off the side board and dig into my top. Thanks!

[@Unclebuddy01]

Thank you for posting this video. I have a new top for my workbench and, because I lack sufficient clamps, it was cupped when the glue dried. I now have a perfect way to flatten the top and save a project gone wrong.

[@davidlittle611]

Those sharp square edges on your workbench are satisfying my soul.

[@anthonymineo6293]

Helpful video. I used the Freud bit and the fixture was super easy to build. Great outcome. I also added a sacrificial board on each side inside the rail so I could go all the way across the work piece resulting in no post planning.

[@andrewludlam5686]

Thank you for sharing this, it is brilliant. Your whole take on generating a 'Reference Surface' has expanded my mind and opens up some innovative ways of sizing/thicknessing . SUPERB Sir.

[@symonf1966]

Simple idea perfectly explained. That's what I like about your videos, I'm never left not understanding a bit of the process. Thanks.

[@spencer6389]

I wish I could have seen this video a lot sooner! I'm in the process of making a work bench out of 2x4's and have already started flattening out the table top surface. I used a electric hand planer to knock down some of the high spots and now I'm using a electric sander to finesse everything out. I ran into the same problem you did with one side in need of some serious planing. I wanted my workbench top to be around 3" thick, but that's not gonna happen. I'm already below that just to make it flat enough to my liking. Thanks for the really cool video!

[@crossthreadaeroindustries8554]

Excellent share, thank you. I just bought an old, heavy shop workbench with a pretty beaten block top that needs to be taken down about 3/8" and this will definitely help finish it off.

[@frankielee1373]

Fantastic video, I will be doing this next week. You have a great way of teaching. Thank you.

[@robertbamford8266]

Great use of an “old” trick. Also a great example of how useful mathematics can be. 3 points determine a plane so with two triangles (rail, diagonal) sharing a common side (the rail you selected not to adjust), you are ensuring the fourth point lies on the same plane. I’m going to give this a try today, and I expect to have to play around with picking my reference rail as I have no clue as to which corner is the lowest. Thanks for the inspiration!

[@AwesomeRedKite]

Thanks for the fast response! I've been watching your videos for a long time and have found them super helpful and they've got me really excited about getting into woodworking!

[@boathousepks]

I tried it and it worked quite well. I made a Roubo with some construction 2 x 6's. I needed to flatten the top and this took all the hills and valleys out of the pine. I am very pleased with the results.

[@CragarShinoda]

My other suggestion is a simple one. I build hot rods for a living, and when I block sand a car I use a dry guide coat (found at your local auto parts store that sells paint). 3M makes the best. I keep a jar of it when I am doing work like this, too. It comes with a soft pounce pad, and is just a dry graphite or charcoal powder. It's a lot easier and quicker to apply over large surfaces than pencils, and is much easier to see. It also sands off easily whereas pencils can embed in softer woods.

[@doughaber3330]

Bravo! If I make a new bench, this video will be studied again! 99.99 percent perfect video. I would like to entertain what would happen if you reversed your sled on a test piece to confirm. Very scientific! That's bro!

[@joshoertle3779]

Great video, Thanks. So many people on youtube are annoying to listen to but you're not.

[@benburoker5192]

You're the first wood worker outside of Canada that I've seen use Robertson screws!!! Smart man!

[@thomasarussellsr]

Ben Buroker i use them all the time. However, I have only a few rudimentary videos and nothing well filmed. I build and make things, I have no filmography skills.

[@hotrodhog2170]

Izzy Swan uses them all the time

[@1Cross1Way]

Ordered my router...starting my sled build this weekend! Thanks!

[@woodwhisperer]

Yes. You can immobilize the board on a plywood sled using hot glue and shims. Give it a few light passes through the planer to clean up the top face. Then remove the piece from the sled, flip it over and send it through again.

[@user-fg3xf1qx8x]

Марк,привет.Приятно идосадно,что ты перехватил мою задумку.Всё равно хорошо получилось.Молодец! Мне нравятся такие ребята-рукастые и головастые.

[@AZQuadRunner]

Excellent technique. To eliminate those triangle remnants on the outer edge, attach a 2-3" wide strip of 1/4" hardboard to your rails. Attach the hardboard to the side of the rail that will lay up against the edge of your bench (as a spacer), ensuring the strips are set below the surface of the bench. This allows the bit to completely pass over the surface of your bench.

[@JackHughesRichmond]

AZQuadRunner Ninja'd. I suggested the same thing. Glad to know some had the same thought - I should have checked first!

[@VladMalik]

Very nice and thorough! Thanks for going over every step.

[@gracenjuguna7292]

Very simple and clear explanation. Thanks!

[@Roidragin]

I like this guy, if not for any other reason than his shirts.

[@gabbleratchet1048]

What a fantastic video, really simple but extremely clever idea, I can't wait to build one and have a go. Thanks.

[@craigbrown1416]

I love your show man! thanks for being here.

[@GuttenMedHatten]

Thank you so much for this video!! I have learned sooo much by only watching two of your vids! I have a work bench that really need to flattened in a proper manner. But instead of using the plastic thread as you are using, i think I am going for using a 1 mm fishing thread. It is not that easy to see, but it is hard (so it vill not be pressed together) and can be tightened very hard and does not weight much, so it will keep a very straight line. Amateur Guitarmaker form Norway.

[@newzerozeroone]

Probably the best use of the phrase "drop the bass" I've heard in a while.

[@scrapdaddyrkc]

built this jig after watching your video ,, worked great ,,,,,, thanks

[@woodwhisperer]

It could, as long as you are sure it is straight and you clamp it to the bench in several places so that it doesn't sag at all. As for the bits, that was covered in the video as well as the writeup.

[@eliehabib3115]

What can I say, Excellent concept Well done will definitely using this idea

[@MURRD0CK]

Ok I see. So as long as the bench is flat then that's all that matters since most pieces need only be flat and square. Level would only come into play when you are attaching a tabletop or something, and as long as your pieces are flat and square then they should be level as well. Very logical thinking Marc. Thanks! :-)

[@woodwhisperer]

Yikes! So sorry to hear about the accident. I think the best thing is to first take a break for a while. Get your head clear, watch some videos, and get pumped about woodworking again. From there, I would start off easy. Do a simple and quick project. Avoid the planer for now. Get some help from an adult/parent who might know something about woodworking. Just get comfortable being in the shop again before jumping into a big project requiring the tool that did the damage. Stay safe!

[@byronbuxton8214]

Good video. Love the string technique!

[@xfup]

I may have just never noticed the stroboscopic effect on a drill bit before, but I think you captured it perfectly lol...

[@omgname]

Thanks for the nice instruction. I make a butcher block top wood bench but was having trouble flattening. This looks easy enough to do. :)

[@dutkal77]

I just watched this video again (as I am laid up in post surgical recovery for a few weeks and am reviewing many videos on this technique) and the thought came to me that if, when you attached the rails to the side of the bench, if you were to put another 2x4 spacer between the actual rails and the workbench, then your router would be able to come fully across the workbench without leaving the little triangles of undone material.

[@julier1080]

+Loren Dutka Or even a strip of 1/2" plywood. He also needs guide rails mounted on the sled (outside of and parallel to the 2x6's) so it isn't slip slopping all over like that.

[@alekjuskevice]

Nice job. Inexpensive materials (as in not expensive) not cheap (as in poor quality) My pet peeve your awesome. Thank you!

[@jamesmjubran]

Just bought that Freud bit, looking forward to flattening a couple of book matched pecan slabs!

[@tubbz691]

Have used a router on aluminum quite a bit. Steady hands are needed, along with WD-40 or aluminum cutting fluid. Good bits are a must....

[@Mario-gu3oc]

I used this technique to flatten a commercial workbench which had high and low spots. It worked very well. Thanks Wood Whisperer!!

[@musamor75]

Thank you very much Marc for this enlightenning video. I also see you're a Festool man ! That's all the credit to you for your good taste. I'm aiming at building my own bench pretty soon, having at last found a good copy of the Emmerit vise. Here in Paris I've been using worn-out old benches for decades, so I think it might be time to personalise my own one. In Europe we tend to use beech. I'm actually considering using hornbeam in 3 layers- middle cross graining (?). I'll look you up again soon

[@frankjames4573]

WW.... Hi... From the UK... Nicely executed tutorial vid... Well explained... Thanks... Frank...

[@mlubecke]

Marc, well done... This was one of your best video's. You really have become a good teacher and videographer- I really enjoy the video's !!

[@claytonhillier6587]

I have seen videos on people basically planning boards, one side then the next, and it seems to work out just fine. the jig is a little different but the same idea and i plan to try it myself soon.

[@TigerCarpenter]

the best explained strings hack to make the rails parallel. well done! I wonder if your workbench now looks thinner on one end, where you removed 1/4" = 6mm or even more as it seemed of the material. of course that wouldn;t matter, as long as the top is flat.

[@Telemorris]

In your application the plastic coated wire wouldn't make much of a difference. However thick cord might make for up to 1/16" difference. I'm going to try this on my bench later. Thanks for the tip!

[@brancaypinky]

This is exactly what I was looking for. Practical, easy to build, cheap and accurate. Many thanks for sharing!!

[@woodwhisperer]

You certainly could. They aren't necessary, but that's one of the ways you could really trick it out if you wanted to.

[@woodwhisperer]

Thanks for the kind words. And no, this technique is not quite the same thing as a planer. A planer relies on the first side of the board being flat already. After you run it through the planer, the second side will then be parallel to the first, and of course flat as well. But in this case, we are flattening one single face. You might do this on a board that is too wide for the jointer. Flatten one face and THEN send it through the planer to clean up the other side.

[@Dwillems26]

First off let me say I love your stuff! Second, i'm using your exact setup to flatten a large slab of walnut. It works great. The only thing I added is stops to the bottom of my runner that the router slides on. Mine are just clamped on. it's one less thing to worry about the sled falling off the rails. It happened to me. Luckily I had to route enough that I took it out.

[@woodwhisperer]

I think it comes down to control. I guess if you could get the planer into some sort of controlled carrier it might work. But the router allows you to move in any direction and very effectively control the depth.

[@pgtips4240]

Fantastic example, great job.

[@BoranTheki]

The cross hair technique is a good idea. We use it when installing door jambs. Many installers will use jet line. That's that very thin orange string used mostly by ceiling tile installers.

[@EMOxxSLAYERx]

I have one of these because I deal with live edge slabs quite a bit. My side rails are made with 8020. They are a 100% flat, light, and have groves to attach your top sled into. Not the cheapest thing, but if you are using it a lot then it is well worth it

[@ffrillici79]

Thank you. I think the trick of using wire allows you to make the two lateral guides lying to the same plane and not to make them parallel.

[@badlandskid]

A couple of ideas I think may have merit. One, screw a 1 x 4 to the inside of each 2 x 6 rail to give you an extra 3/4 inch. That way your router bit would eliminate the triangles at the end of each pass. Second, attach a couple blocks to the underside of the sled just to the outside of the rails. That will keep the sled from accidentally falling off the rails and averting a large oopsies... Thanks for the great video.

[@bruceporter3442]

For those wondering about "raising one end and lowering the other" to keep the strings just touching... Yes, you can raise the far left end and lower the near right end (for example) and keep the string just touching BUT the two guide rails would STILL be coplaner (not level of course but that is not the goal). In this example the whole top would be coplaner and slope toward you from far side to near side.

[@CragarShinoda]

Another great video, Marc! I do have two suggestions though- since you did ask. ;+) Can you not place a piece of 2X4 in between the sacrificial rails and the workpiece, just a little bit below the calculated deepest cut (i.e. if the highest corner is 1/2", drop the 2X4 5/8" below the surface) and make the sled just a little wider. This will allow a space for the router bit to run off the sides, not make the 6X's sacrificial, would be easier on the bit, and probably eliminate the triangles.

[@ramanshah7627]

Beautiful work. This took some thinking (taking me down the garden path of optical mounts from Thor Labs and ideas for some custom machining), but a great tool that can obviate the string work is a laser level. Back the laser level off enough to illuminate the insides of both rails, and that should give you an easy way to get the rails nicely coplanar.

[@latrappe800]

Used this to flatten out three large chopping blocks with 30 years on them. Great trick

[@bruceporter3442]

Two points about the accuracy of this setup. First, I am using the same coated cable and I noticed the cable stands up above the wood where it bends around the 2x6 corner, leaving the bottom cable just slightly above the plane of the 2x6. If you are very concerned, you can weight it down so it sits flush with the wood. Secondly, if you sight along the cables you can see that there is a slight sag over the length. As long as the cables are both at the same tension there will be equal sag and it all works out. It might be better to use something more supple and light weight such as fishing line. Both the sag and flush problem would be eliminated. With fishing line it is so thin that you would also not need to worry about the thickness problem (supporting the wire with a scrap of cable). This is all assuming that the accuracy gained is all that important...

[@rickreed123]

Thanks for the great video. Very useful information. Concept could be extended to many applications.

[@jennynewell6941]

Couple of easy improvements, firstly make the side rails from two pieces glued together - the inside ones JUST lower than your working level so you don't route into them and so they are always re-usable (effectively the side rails are 'L' shaped). Not too low or you might get tear-out at the sides. Then also attach a couple of short (perhaps 2-foot) rails near the ends of the sledge at 90 degrees to it that run outside your long rails so that it is not able to move side-to-side when you slide it along, they also keep it at around 90 degrees to the workpiece. Hope this helps

[@woodwhisperer]

It's really just a large straight bit. Although you might find some interesting options under "bottom cleaning bits"

[@MehdiSheikhLovesPie]

Instead of the whole string ensemble to get the rails parallel to each other here's a better idea. Two straight edges. Two laser pointers on one. Two targets on magnets at the same height of the laser pointers on the other. Nothing goes straighter than light. Those rails also will always be usable.

[@coder4liberty]

Stone Coat Countertops has a jig. It's expensive but it gave me a design inspiration. I think they used 80/20 track for theirs but I think you could also use t-track and then mount the t-track on plywood panels to keep them from bowing. Stone Coat uses a caster system to roll along an already flat desk and theirs rolls along the top. You could also make something similar which rolls along the bottom or use rails like you did. The big box stores have steel angle and square stock which is probably pretty straight and maybe those would make even better rails.

[@MrB82901]

Thank you, I have a large solid table top that I want to level, and you just gave me the answer. WooHoo

[@miketaylor5576]

Nice, I made one out of 1-1/4 uhmw or white plastic, thanks for the idea!!!!

[@rxe9231]

Great clip and example Thanks for sharing

[@EnJineer89]

Corrected this part: I was wrong. I thought the wire trick wouldn't work in all cases, but I do realise now you are right and I was wrong! Thanks for sharing the idea. Although, I think it is kind of risky to use only two 2 points to set them parallel, how sure are sure can one be that the rails are straight? I'm also wondering how accurate it is, how many degrees can they be not parallel before the wires don't touch any more? Therefore, I think it's better to shim the workbench and use a level. One could even use an engineers level (metalworking) which typically have a resolution of about 0,0002 inch / inch or better and only cost about $50. They exist from a length of 2 inch I think, so you could even use them to map the top by moving it over the complete area to find the low spot, although not really required as you'll notice it after the first passes anyway. An other advantage from using a level is that if you level up de workbench you're sure it's not distorted (twisted). But I like the simplicity of the method, easy, fast and cheap!

[@pedesign5686]

Thank's for the idea, my problem solved finally..

[@jeffstanley4593]

Great video. I mean really well done and super informative. Even I might be able to do this after watching how you did it.

[@5460sundance]

Very sharp the way you crossed the lines with the extra piece of line. thanks for this tip.

[@TomKaren94]

Flat is SO much more important than level in glue-ups, etc. I make desks that require a 22x48 top. I have a 36x60 homemade workbench made from jointed fir framing and a doubled-up-3/4"-thickness (1 1/2" total) MDF top. I drilled vertical 3/8" holes near each corner, and I use dowels and strings to check flatness on a regular basis. Since I'm using the top as a flat for my panel glue-ups, the flatness, not the level, is important.

[@tango-bravo]

Nice video and methods. Will incorporate several of your ideas in a jig we are building. You got excellent results...hopefully we will as well. Have a good one...

[@ziadalbaff268]

Hi I've just watched this video ... along with almost all you video. It was great and very helpful. I have an idea though conserning making the rails parallel. Just use squared piece of wood or aluminum with a lazer pointer mounted on it on one corner. And a 90 degree ruler on the other 3 corners. It will cost nothing.

[@JgHaverty]

Neat trick for you perfectionists out there. Use a peice of square stock and clamp it to the board. Use that as a "guide" to get a perfect, square cut on long lengths of cuts. Perfect for jigsaws with flat edged bases.

[@woodwhisperer]

Yup. That should work just fine.

[@woodwhisperer]

You're very welcome!

[@woodwhisperer]

I see. I would say yes, it would definitely be more susceptible to tearout. With a nice sharp router bit, taking such a light pass, there is no tearout to speak of.

[@woodwhisperer]

It's a mental gymnastics sort of thing. But I'd like to make one last point. The plane is not arbitrary. Most workbenches are mostly flat to being with. When you initially set up the rails, you set them an equal distance from the top of the bench. You make very fine adjustments from there. This gives you a flat plane somewhere close to level. For a workbench, that's good enough. Again, I would never disparage other methods. But I assure you this one works quite well.

[@NV..V]

Another great video. Thank you paisan.

[@foxglovemead]

Used the sled to level wide glued boards. I didn’t use the crossed strings - I’m not convinced it ensures sides are parallel. I preferred to use guides of desired thickness and existing workbench to level boards. Guides can be below or level with boards especially if router movement is limited by end stops. Routing uphill and along boards not going side to side gave me best results. Used same sled to create two curve lengthways on a bench. String crossing would be ok if there is a guaranteed level at one end e.g. you had 1/2” drops and confident this was already level? Simon

[@walterkiel552]

Great technique! Thanks!

[@whosaidthat5236]

4 rollers on each end of the sled and it will roll across the rails really smooth. and rabbit your runners so they don't have to be sacrificial put a stop on each end so you don't hit the runner and you have a great router sled