# Planing slabs with a router.



## xpuser (Dec 8, 2013)

I know that this has been discussed in some older threads , but the pictures seem to be gone on all of them I looked at. Was wondering if some of you that do surface your slabs with a router would care to post some pictures of the setup you use. 


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## jrhannum (Dec 9, 2013)

here're pics of mine


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## BobL (Dec 9, 2013)

I only have pics of when my rig was in its short (3 ft long and 2.5ft wide) version and have since made it longer (6ft).
Here you can see I was using it to place the end grain of a cookie.
It bolts to the back side of my workbench and is held at the front by the big vice



The router rides in this carriage and is moved by hand back and forth across the wood surface


Equal numbers of turns of the cranks move the carriage the same distance down the length of the slab.


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## xpuser (Dec 9, 2013)

jrhannum said:


> here're pics of mine


Looks like that will work. Do you just move it up the slab a little at a time by hand or do you have something to control how much it is moved. 


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## xpuser (Dec 9, 2013)

BobL said:


> I only have pics of when my rig was in its short (3 ft long and 2.5ft wide) version and have since made it longer (6ft).
> Here you can see I was using it to place the end grain of a cookie.
> It bolts to the back side of my workbench and is held at the front by the big vice
> View attachment 321530
> ...


That's a nice looking rig. I like the way you add it to your work bench. What diameter bit do you use. 


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## BobL (Dec 9, 2013)

xpuser said:


> That's a nice looking rig. I like the way you add it to your work bench. What diameter bit do you use.


I use a 2" bit with slightly rounded edges. The extent to which I overlap the cuts depends on how hard the wood is - given the bit is rounded a 2" wide cut will leave small ridges so I typically use a 1.5" cut.

I did these 2 bench tops for these shop benches with this rig. I just used it to take the chain corrugations out and flatten the top and then used a 4" belt sander to sand then smooth.
I wasn't particularly fussed about getting an exact thickness or getting the two slabs the same thickness which made things a lot easier.


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## xpuser (Dec 9, 2013)

BobL said:


> I use a 2" bit with slightly rounded edges. The extent to which I overlap the cuts depends on how hard the wood is - given the bit is rounded a 2" wide cut will leave small ridges so I typically use a 1.5" cut.
> 
> I did these 2 bench tops for these shop benches with this rig. I just used it to take the chain corrugations out and flatten the top and then used a 4" belt sander to sand then smooth.
> I wasn't particularly fussed about getting an exact thickness or getting the two slabs the same thickness which made things a lot easier.
> ...


Very nice. Thanks for the info and pictures. 


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## 7oaks (Dec 9, 2013)

Beautiful workbench Bob. And I like the design of your router table. Just might try to make someting similar myself.


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## BobL (Dec 10, 2013)

7oaks said:


> Beautiful workbench Bob. And I like the design of your router table. Just might try to make someting similar myself.



Cheers 7oaks. Unfortunately those benches, like most shop bench,s are now all covered in "stuff" The one on the left has become my rechargeable battery station while the one on the right is covered with a tool rack and a bunch of metal work cutting bits. The slabs came of a Eucalypt (Western Australian Red River Gum) that was grown only about 10 ft away from where those benches reside i.e. just outside my shop. I have about another half dozen of those short slabs under my house waiting to be turned into something


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## 7oaks (Dec 11, 2013)

You've got some beautiful wood down under. I've got lots of 3" slabs of spalted maple, black walnut, black cherry etc but I just can't force myself to make them into work bench tops. As you say - they'd be covered in an instant. The wife will not let me create any new flat surfaces in the house as she says I just cover them with junk anyway. She's a little bit right. LOL


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## busch_6 (Dec 11, 2013)

I used my CSM to mill up a 5' diameter poplar 2 years ago that had a reasonably clear trunk up to about 18 feet. The slabs were finally dry enough this fall to contemplate getting them in shape to do something with.

To prep the slabs I built a "planer" table using my 3.25 Hp router to flatten the slabs.
I took pointers from various places as well as a few ideas of my own and came up with the following. Attached are some drawings of the basic pieces (some mods happened real time and are not reflected in the drawings). I also included some pictures of the finished product after flattening one side of a slab.

Following is a description of the major pieces

TABLE:
- The table is very large and takes up an entire bay of my garage. That said it comes completely apart with deck screws.
- The side rails are made from engineered floor joists. This was one of the better ideas in the project. The floor joists can be ordered in any length, are very straight and warp little to nothing with changing humidity.
- The entire table sits on 4 saw horses, one in each corner that straddles 2 of the 2x4 stringers.
- Each 2x4 stringer is screwed to a short piece of 2x4 that is glued to the web portion of the joist on each side.
- I pulled a string in a cross pattern across the whole table and then shimmed under each saw horse to get the whole table flat. I have checked the table for flatness occasionally and only once did I need to change the shim under one of the saw horses by about 10 thousands. 10 thousands over a 6' by 18' table is basically nothing.
- I ended up screwing 4x4 lengths of posts to each 2x4 stringer. This served 2 purposes. First, the 2x4 stingers between the two side rails did not have a consistent height, or at least not enough for my liking. I used some old (and straight) 4x4 post pieces and was able to shim them all up and get all of the 4x4s at exactly the same height. Second, since I used 12 inch floor joists the table was a bit low for the thinner slabs, so the 4x4s brought up the top surface of the slabs closer to the router.

SLED:
- It was a bit of a challenge getting the 2 bridge boards in the sled flat enough for my liking, but with some sanding/planing and adding stiffeners they turned out fairly well. I added a 2x4 on edge to the pivot side of the sled and then I added 0.25” thick x 1.25” tall steel straps to both sides of the longer board on the sled that the pivot slides back and forth on.
- I used 2x4s on the outside of the joists to keep the sled on the joists.
- Bolted an old cable winch to the stiffener on the sled that goes through a pulley in the center of the sled and then to the end of the table. This allows a single person to both move the pivot as well as advance the sled between passes without moving much.
- There were a couple of instances where I needed a little more height for the sled to make it over a thick slab. The easy solution to this was to just insert a 0.75 inch thick lumber between the engineered floor joists and the sled bridges. Since the board connecting the bridges on the outside of each joist was a 2x4 there was ample freeboard to keep the sled centered on the table.
SLED PIVOT:
- I edge glued two 2x6 boards for the pivot. This proved to be stiff enough even once I cut out the hole for the router.
- Built an aluminum shoe for the router base to screw to.
- The router base is shimmed down so it just misses the tops of the joist side rails as the pivot swings to the extreme ends.
- Used a 2x2 that sits on a bolt as the push stick for the pivot. I mounted a tractor steering wheel knob on the end of the push stick to give something to hang onto.

ROUTER:
- For the surfacing bit I used a 2.5” Her-Saf surfacing cutter head (#H-R2515 $165) and separate 1/2x3.25 inch arbor (HA-50AT $10.50) with replaceable carbide inserts ($8 per pair). This setup cost more, but I feel it was worth it. So far I have surfaced probably 800 – 1000 square feet of plank surface and generated probably 10 cubic yards of chips and I feel it has paid for its self. Each set of inserts have 4 surfaces so it they can be rotated 4 times before being replaced. Hitting a bit of dirt in a crotch or accidently dropping the bit on the floor and breaking a carbide insert is not a devastating event. Another nice thing is that if I sense I may get into some dirt I can shift to an old set of cutters.
- One word of caution. The Her-Saf surfacing cutter heads have arbors that are sold separately and screw into the head. I inadvertently snagged the surfacing bit 2 times and have broken the head off the arbors twice. After thinking about this, it is probably a blessing that the bit is designed this way. If this mongo bit catches and something has to give it is better to ruin a $10 spindle than a $165 router bit head or a $330 router. After breaking the 2 spindles in the first 200 odd square feet of surfacing I have not had another issue. Probably mostly comes back to the learning curve.
- With the Her-Saf 2.5 inch bit I could cut a 2 inch swath and about 0.2 inch deep cut per pass in the poplar. Cutting a 2 inch swath worked well for mass material removal, but sometimes caused some grain ripping. Reducing the cut for each swath to 1.0 to 1.25 inches virtually eliminated any grain ripping and produced a finish ready for sanding.
- I started with a friend’s 3.25 Hp. Porter Cable router. I did not want to wear his router out so I bought a 3.25 hp Makita plunge router and it worked a bit better. It seemed to have more power.

PERFORANCE:
- The biggest slab I have flattened is about 55 inches wide and over 14 feet long. The maximum variance I was able to measure around the entire slab with the calipers was about 20 thousands of an inch. In localized areas (2-3 feet) the variation is less than a few thousands. I think this is pretty good for over 60 square feet of slab.
- From pass to pass with the router it is nearly impossible to feel any variation in height meaning there is less than 1 thousands variation from pass to pass.
- The engineered floor joists worked great and I sense dramatically improved the overall outcome of the table and its performance.
- One of the limiting items on the output of the table was the power output of the router. I did look for a larger router (say 5 hp 240V) and could not find such a monster.
- After I am done, the whole thing comes apart with deck screws. The only slightly obnoxious pieces to store will be the long engineered floor joists.


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## betterbuilt (Dec 12, 2013)

I have my sled here. https://plus.google.com/photos/107614430480833197202/albums/5956565618932559857?banner=pwa
here's my low tech approach to leveling slabs. I'd love to have a 3 1/4 horse router and a bit like busch_6 has.


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## xpuser (Dec 12, 2013)

busch_6 said:


> I used my CSM to mill up a 5' diameter poplar 2 years ago that had a reasonably clear trunk up to about 18 feet. The slabs were finally dry enough this fall to contemplate getting them in shape to do something with.
> 
> To prep the slabs I built a "planer" table using my 3.25 Hp router to flatten the slabs.
> I took pointers from various places as well as a few ideas of my own and came up with the following. Attached are some drawings of the basic pieces (some mods happened real time and are not reflected in the drawings). I also included some pictures of the finished product after flattening one side of a slab.
> ...


Very nice setup. Lots of good ideas there. 


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## xpuser (Dec 12, 2013)

betterbuilt said:


> I have my sled here. https://plus.google.com/photos/107614430480833197202/albums/5956565618932559857?banner=pwa
> here's my low tech approach to leveling slabs. I'd love to have a 3 1/4 horse router and a bit like busch_6 has.


Looks like that will get the job done. 


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## MGoodwin (Dec 12, 2013)

Instead of using a swinging arm witht the router mounted on it, I have a sled that I run lengthwise for each pass that runs on a pair of 8020 aluminum rails (nice because they are straight and I can mount them to the bench top). One of the attractions to this design was the addtional weight of the sled to help ensure the router doesnt "jump" while cutting. The biggest down side is the width of the sled as its nearly twice the width of the rail spacing. Have you had any problems with the router jumping or skipping around? If I were to do this again your design looks very attractive.


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## busch_6 (Dec 14, 2013)

MGoodwin said:


> Instead of using a swinging arm witht the router mounted on it, I have a sled that I run lengthwise for each pass that runs on a pair of 8020 aluminum rails (nice because they are straight and I can mount them to the bench top). One of the attractions to this design was the addtional weight of the sled to help ensure the router doesnt "jump" while cutting. The biggest down side is the width of the sled as its nearly twice the width of the rail spacing. Have you had any problems with the router jumping or skipping around? If I were to do this again your design looks very attractive.


 
I have not had the router jump even once.


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## gr8scott72 (Dec 15, 2013)

Here's my little set up.


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## xpuser (Dec 15, 2013)

gr8scott72 said:


> Here's my little set up.



That looks good. Why don't you cut with the router in both directions? Do you have rollers in the track or are you just sliding on top of it? 


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## gr8scott72 (Dec 15, 2013)

xpuser said:


> That looks good. Why don't you cut with the router in both directions? Do you have rollers in the track or are you just sliding on top of it?
> 
> 
> Sent from my iPhone using Tapatalk



I would have to cut on the return path on the side closest to me to get the router to cut the correct way. It was just too much travel to do that. 

Since that slab, I have stared taking smaller bites so that I can do just what you asked. I'll do like 1/4 of the slab at a time cutting in both directions. 

No rollers. Just slides. I add a few drops of 3 in 1 oil every so often to keep it sliding nice and easy.


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## betterbuilt (Dec 19, 2013)

gr8scott72 said:


> I would have to cut on the return path on the side closest to me to get the router to cut the correct way. It was just too much travel to do that.
> 
> Since that slab, I have stared taking smaller bites so that I can do just what you asked. I'll do like 1/4 of the slab at a time cutting in both directions.
> 
> No rollers. Just slides. I add a few drops of 3 in 1 oil every so often to keep it sliding nice and easy.



Do you have any close ups of the finish the router makes going that direction. I've always wondered if you went with the grain, if the finish would be any better. The next small slab I do I'll try that way.


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