large surface flattening jig - router setup - question

[Dennis Peacock]

Has anyone here ever built a sled / rail system for running a router with a large bit over the surface of a large wooden slab to flatten the surface of the slab with? I'd love to see/hear about your setup.

[James Zhu]

http://www.infinitytools.com/shop-essentials/education/woodworking-plans-projects/slab-flattening-router-jig

[Kevin Jenness]

Shim your blank level on a flat surface and clamped between two parallel blocks taller than your blank. Put some spacers between the blank and the parallels. Make a sled for the router of 3/4" melamine or ply covered with p-lam just wider than the router base and long enough to span the parallels plus a few inches, with side rails to capture the router and stiffen the sled vertically. Add guides on the bottom of the sled to run along the parallels and stops on the top to confine the router travel within the parallels. Plunge through the sled to make a slot between the stops. Now run the router side to side and the sled along the parallels until the blank is flat. Plan for bushels of shavings.

James Zhu's link shows the essentials clearly.

That's how I did it before I had a cnc router. If you have one close by it will save considerable aggravation.

[Bryan Lisowski]

Marc Spagnolo did this when he built his Roubo bench and posted a video on his free site as well. The other would be the Samauri Carpenter did the same to flatten a 60" wide piece. Router planning sled should give you options in Google.

[Ken Kortge]

Eurekazone.com - the company that makes an excellent guide rail system that uses your circular saw - also makes what they call a Super Smart Routing System (SSRK) that connects to just about any router and accurately guides it along two dimensions.

Though they don't list it on their web site, their SSRK User Instruction Guide (http://www.eurekazone.com/v/vspfiles/assets/pdfinstructions/EZ%20SMART%20Super%20Smart%20Routing%20Kit%20v14-01.pdf) (a pdf file) shows what they call a "Dual Routing Kit" for exactly what you want to do - flattening large slabs.

Eurekazone.com is a relatively small U.S. company that is based out of Ocala, Florida (I've used their guide rail system since 2008), and they seem happy to take product related calls. Give them a call and I think they'll help you find with your needs.

[John TenEyck]

It's pretty darned simple. Two parallel rails, and a bridge that's twice as wide as your slab.

https://lh3.googleusercontent.com/aYU_pZVPOQlj2GLNi1JQ3DYp6KbIftORqCI7dziMkN9jZ1I-A5fpBJfjPpSsvA1Lk0CV2-aM6Xtor0xQdd48RGBOeenvCEVDmTX1ddciuURbsrwnIV0Bfpho rGq6BFtZT0f6-eMFpxn9hIddZtZUOQ3LGBza2DY1N0_AcX2UHO87HZi7nU9cPrc 923zUctC3Dn7pieAHwlAR34ZdRP-CXsW-n6D82eZqtOSObDb2jfac54ASQ1g_VGTrp4w5stQjYvk-55sy-nPE0C3EcXZj6jx-nK7qBxpNgQOwTLxzUzGHPgAA7UeQCRNcH7JHaP9V_GBWfxIUpU clptPZaS9kdPxSmSN6INzBPDetoWquDrZsfkQs-0skdg2cXL0pD_Qoyt-f--jH_x4v6FU8xDx7TAfr6_0sisZhlIEe9Ov08sRQwC56JNFCkhAR ZOmEscujkUDhU5hdWvZL4fAYQH31ZTXAe2g8gyuzwKvtcaH-mnCJuHCWLLcd66dXpuzWMKTTsO2r99RvDIZRcr4Tx7x-MM-ZfIWYUY1RM1WDapevBx44yNtJPXw068W8RmcJk613eGLTLsSf5 ziS4DdVaZAbLqcWRdaO_Ko0BisuYmT1U9r5CyLr=w640-h480-no

I did this with a 1/2" straight bit.

John

[Mike O'Keefe]

Volume 38 of The Woodsmith magazine has a article on building a flattening jig. Mike O'Keefe

[Dennis Peacock]

Thank you everyone!!!! I now have all kinds of ideas running through my head. :D

[David Eisenhauer]

Dang Dennis. The crew knocked that one on the head right now. I think we need to get up a little earlier in the morning to stump this crew.

[Rick Moyer]

It's pretty darned simple. Two parallel rails, and a bridge that's twice as wide as your slab.

https://lh3.googleusercontent.com/aYU_pZVPOQlj2GLNi1JQ3DYp6KbIftORqCI7dziMkN9jZ1I-A5fpBJfjPpSsvA1Lk0CV2-aM6Xtor0xQdd48RGBOeenvCEVDmTX1ddciuURbsrwnIV0Bfpho rGq6BFtZT0f6-eMFpxn9hIddZtZUOQ3LGBza2DY1N0_AcX2UHO87HZi7nU9cPrc 923zUctC3Dn7pieAHwlAR34ZdRP-CXsW-n6D82eZqtOSObDb2jfac54ASQ1g_VGTrp4w5stQjYvk-55sy-nPE0C3EcXZj6jx-nK7qBxpNgQOwTLxzUzGHPgAA7UeQCRNcH7JHaP9V_GBWfxIUpU clptPZaS9kdPxSmSN6INzBPDetoWquDrZsfkQs-0skdg2cXL0pD_Qoyt-f--jH_x4v6FU8xDx7TAfr6_0sisZhlIEe9Ov08sRQwC56JNFCkhAR ZOmEscujkUDhU5hdWvZL4fAYQH31ZTXAe2g8gyuzwKvtcaH-mnCJuHCWLLcd66dXpuzWMKTTsO2r99RvDIZRcr4Tx7x-MM-ZfIWYUY1RM1WDapevBx44yNtJPXw068W8RmcJk613eGLTLsSf5 ziS4DdVaZAbLqcWRdaO_Ko0BisuYmT1U9r5CyLr=w640-h480-no

I did this with a 1/2" straight bit.

John
Two questions:
1> why does the bridge need to be twice as wide? As the router reaches the outside seems sufficient to me.
2> how long did that take with a 1/2" bit and why not use a larger bit?

[Prashun Patel]

It doesn't need to be twice as wide. It just needs to have a slot that extends the length of the slab.

All this is to say, a wider bit doesn't always translate to less work in this application.

You CAN use a wider bit, but 'planing' with such a 1 1/4" ish 'bottom cleaning' bit is tricky. The bit can be prone to running away and it requires good power on the router to handle. Any abrupt changes like skipping can cause a larger bit to alter depth ever so slightly. Enough to make more work for you. So, I find with a large bit, you end up having to take very shallow passes. The process for me is less like 'planing' (using the bottom of the bit) as it is a series of flush trimming cuts (using the side of the bit). A 1/2" or 3/4" bit gives IMHO better control.

Whatever bit you use, this planing process requires careful smoothing after.

[John TenEyck]

You can put a slot in the sled that is only as wide as the rails, as Prashun said, and slide the router side to side. Or you can screw the router in the middle of a sled that's twice as wide, as I did, and then slide the sled side to side. I found it easier to do the later, personal preference.

My experience with big wide bits is similar to Prashun's, so I typically use a 1/2" bit. I think it took me about 45 minutes to flatten each side of the slab. I had to make a couple of passes, changing the depth of the bit in between, because the slab was pretty warped. You can see in the photo above where the bit isn't even hitting the slab at the ends and is cutting almost 1/4" deep in other places.

John

[Prashun Patel]

One more tip on holding the slab down:

You should make a series of 12" x 1" thick tapered wedges. It is critical that the slab not rock as you do the first side. These wedges can be slid underneath the slab.

Next, you will have to position your rails far enough away from the widest point of the slab such that your router doesn't hit the rails. You really want the 'stroke' of the router to begin and end off the slab, or you will get burning at the turnaround point. Like John says, if parts of the slab are cutting as deep as 1/4", you will generate significant force on moderately sized slabs, so you need to prevent the board from moving laterally as well. To do this, use wider tapered wedges between the slab sides and the rails. You can use a set of opposing wedges on each side to basically clamp the slab to the rails this way. Just don't do it so hard that the rails bow.

Personally I've always used the slot/slide the router method, but I am thinking to build a sled now like John suggests. I would also screw handles into the side of the sled so it can be 'rowed' back and forth ergonomically. I find that this repetitive motion can get very tiring. Gripping the handle of the router for so long is fatiguing for me. Also, with my method, you have to hold the sled with one hand, and the router with the other. It's hard coordinating both independently which means I tend to skip and move with the direction of the cut every now and then. This causes skipping. Securing the router to the sled and doing as John does gives more leverage over the tool, and allows you to use both hands to control one dimension of movement. Like.

Ok, John, have you solved the room-full-of-dust problem with this method? BTW, I'm using that same Bosch 1617.

[Rick Moyer]

Thanks guys, great advice. I have a friend doing slabs right now but he's just getting started and thought I could give him some better ideas than what he's doing now. Appreciated.

[Dennis Peacock]

Well, to build John's version of the sled? I'd have to have build a sled to mount the router to that would be 120" long in order to go across the 56" kitchen island top to cut down on the time and effort of sanding it all flat. :) :rolleyes:
I'm just looking to do this for this island top I'm building.....56" wide by 10' long by 2.5" thick

[Ted Calver]

Maybe overkill for your purpose, but here's one I built:
http://www.sawmillcreek.org/showthread.php?226811-Router-Planer-Sled&highlight=
http://www.sawmillcreek.org/showthread.php?226812-Router-Planer-Sled-(Continued)&highlight=

[Jim Becker]

Well, to build John's version of the sled? I'd have to have build a sled to mount the router to that would be 120" long in order to go across the 56" kitchen island top to cut down on the time and effort of sanding it all flat. :) :rolleyes:
I'm just looking to do this for this island top I'm building.....56" wide by 10' long by 2.5" thick
Yea, that length was what immediately jumped to my mind for your particular project. John's version could be a starting point, but there will be a need for intermediate support for 10' length. This is actually timely, because I have at least two table projects coming up, one with slabs, that are going to required a longer setup to handle.

[Jim Becker]

Maybe overkill for your purpose, but here's one I built:
http://www.sawmillcreek.org/showthread.php?226811-Router-Planer-Sled&highlight=
http://www.sawmillcreek.org/showthread.php?226812-Router-Planer-Sled-(Continued)&highlight=

Ted, that roller setup is AWESOME!! Thanks for floating that thread back up in response to Dennis's question!

[Brian Holcombe]

I joint and thickness slabs by hand with hand planes (the type without motors) and it's a good workout. I find the popularity of the router sled slightly confusing, if your goal is to joint the slab would not a handheld electric router along with winding sticks and a straightedge work significantly easier than this approach?

There is a very famous place right near me and, to the best of my knowledge, the approach described above is how they do it....and I'm certain they have worked a slab of two.

[John TenEyck]

Not necessarily. You could make the sled just over 50% wider than your slab, and mount the router so that it is just hangs over one edge of the slab when the sled is tight against the rail on the other side of the slab. When you pull the sled the other way it will reach at least half way across the slab. level one side of the slab, then reverse the sled to do the other half.

John

[John TenEyck]

Somewhat, Prashun. I built a vacuum attachment on the sled, sorta like you see on a CNC router.

https://lh3.googleusercontent.com/G8RQZPdJllZxvOXs7Oktw2b7SbL8HP6Eb3752eAHJTW5ScMi2H 8mdZQmucSbFfekESoGaZaVNjzo26IIQ2_g0IhjkKs6pePw_OeR 2wytK3FK2d_Ky0XcV7yzOnAJtyB29-lvhdKkL5Ir3u3vBGEN08kCGlJMxnxIc3FPWDH8gYRteJoI8upq l2D43Eet2Lq-PDqmNh9XhCpcO5XXJ00Q99Lfg6KLq33aaLd0FlBbXKWmcHz4EW 3td2jDFuAAKw4n7LzotZSSu84gBKh1ofvVfR-s8AYBqRo9UH4gMDraHz35dHijFvCBPAyQMwtq1jcOd84SbOWnH OnOGzqCt__B8auToAUleGQuZp5LaJSazXaqCebXrz0YBLdnN-x09WvGClVCe4PKKC0URT9aS9ZuArdXiKSkQ--j1TBfZHZCwW1qXvIC5L1n6HtzVT0Uz-0QU99Uw9NiDpDdTmoFF3ppfTfiGRbuRcDADBK5rc20eGxY61lc X7SUF_XItWZ4gU3KVTbXOuqpe4YeYIvdEE5IOzrDPnTtyvs5Ki XtuTu3Or5Ux7LL1Qe1sEiRVM5W3yOSXc7-QuP-Wwcx_yzAxzNP2ACtkvFbTwEF7QY9R_yURXBBvgBh=w640-h480-no

https://lh3.googleusercontent.com/DEn5cHEug_NzKXYgMLU7rc0Xc94KiiuCPWP1dGDKTWPMU75Qk5 my0S7kOeUa8JndUopDIzT5oGVNrGN0SYZLztwL7AAn5lGW1qs2 Yg-Z0No4TablrcgReQAvLUooS-WnD_npCz9AGnBWDUq2GAInRTEW5sRFbezfZ3H78uMku1fKYPfq 3L5uQdl6KLV4Q77WmDOwpOxwfPa2p7Hr_GrVPwSfFzMfIEDKPv mvqOjWWt0isunYkg9HJQoUV6g6tNQrQQWFtuLtuPp-TG6ta5efpRywBc8sDscqkYWCJk0ViBI-WbavF0ys4ViCznE4jiOUvA5L2u214rylh3nzSxHqTksSN9eMWW Jo2kOkbPPEFog1ViAUZwp_AjbpEe1iNWvu-9oOMFgHiFqaimF-pwIbHyflb4yhrnx9QAzf5W79h5J1rvVAEKBreWtuf7R4d8k5Tt TqVjr461gru3ahqDYpDanDJiiUIYfEyw94m-YtnBLPTcLxFSW2Oid_342U7tYOZ925rFJoOA95-6oM9d7xK6sz5iKXjI0k05ggkdGv9q1YmNRAm8Cfn3jZ_Wnt1s0 QiU2PW3nPRxYIku894mbBGHZWCUrdwAu8pXyyDO0ARDVY50LY= w640-h480-no

A brush, as used on CNC routers, would have worked better because it would seal better as the router transitions from the rough areas to those have been routed smooth. But I couldn't source any cheaply, so I just tolerated the blow-by I got with this. Overall, I think this captured maybe 2/3's of the chips and most of the dust, which is way better than nothing.

Adding the vacuum attachment was one reason I elected to build the sled twice as wide as the slab. But you are right, when the router is screwed to the sled it's much easier and less fatiguing to use.

John

[Andrew Hughes]

That's pretty slick setup John.
I built a router sled one time only for some Sassafras slabs that I could not tame with my handplanes.
It was a lot of fun.Looking forward to do it again!

[Lynn Kasdorf]

Do you folks have any trouble with the slab warping from the pressure released from routing off a layer? I was talking to some folks that make amazing slab furniture and asked if they use a router jig like this. They said they had the warping problem, so they just use hand planes and story sticks.
I like the router idea better!

[Prashun Patel]

Lynn, I don't believe it's the method (hand vs power) but the speed and depth that is the culprit. Handplanes may encourage the flattener to go slow and perhaps be overall less aggressive with material removal.

Going slowly (meaning doing the flattening over a couple days) and removing material from both sides, helps.

I am doing an oak burl now that is a real bear and is moving a lot on me...

[Brian Holcombe]

Do you folks have any trouble with the slab warping from the pressure released from routing off a layer? I was talking to some folks that make amazing slab furniture and asked if they use a router jig like this. They said they had the warping problem, so they just use hand planes and story sticks.
I like the router idea better!


Winding sticks :) I'm also curious if those who use this process check their work for flatness after. I would imagine it to be fine if one follows the normal approach of taking nearly even amounts from each side.

[Lynn Kasdorf]

Right- winding sticks, not story sticks...

[Larry Copas]

To flatten a glued up slab of that size it will be far faster to do it with a belt sander than fooling around with a bridge. Building a bridge to surface something that big is a project of its own.

Take a pencil and scribble marks all over the top. That way you can see where the high and low spots are as you sand. Your size of table would take me about two hours with a sander. Yes, I have a router bridge and use it with natural edge slabs but nothing near that wide.

This bench top is 40” X 8' and took me about an hour to flatten with the belt sander.

348837

[John TenEyck]

I haven't had any problems with flatness afterwards. I do try to take about the same amount off both sides, but you can't always do that and end up with the thickness you want, so it is what it is sometimes. But as long as the slab is at EMC with my shop they seem to be fine.

As for using hand planes or a belt sander to flatten a slab, much less several of them as I recently did, to each their own. It takes less than an hour to build a bridge from scratch and it only takes an hour or so to flatten a pretty big sized slab. And when you use a bridge, you know the slab will be flat. No winding sticks required.

John

[Brian Holcombe]

I'm making no effort to convince anyone, since I chose to do this method rather than taking a faster approach. A 6' slab without crotch section would take me a few hours to flatten and thickness with hand planes.

It starts to take significantly longer when there is a crotch section, the crotch section dulls the planes very quickly and requires additional re-sharpenings.

[Chris Fournier]

I'm with Brian on this one. The sleds are great and I made one for a "42" Oyster of hard maple". This was of course end grain and that's why I made the sled. For a slab I use a power hand plane and winding sticks and then get to a finished surface with hand planes. This is fast and effective. If the process is as important to you as the project then I understand the sled approach. If you simply want a flat slab then there are other methods that will get you to where you want to be.

[Jim Becker]

Dennis, I know you're already through this project, but check out this multi-router setup by Willard Bros, a lumber firm near Trenton NJ...

http://www.willardbrothers.net/images/slab-cutting.jpg

[Mike Heidrick]

My jigs :)

http://i39.photobucket.com/albums/e169/BloomingtonMike/bretts/IMG_8395.jpg

http://i39.photobucket.com/albums/e169/BloomingtonMike/Cast%20CNC/PC254057.jpg

[Brian Holcombe]

Dennis, I know you're already through this project, but check out this multi-router setup by Willard Bros, a lumber firm near Trenton NJ...

http://www.willardbrothers.net/images/slab-cutting.jpg

looks like we travel in the same circles.