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Thread: Shop Project: Slab Flattening Table With Additional Uses

  1. #1
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    Shop Project: Slab Flattening Table With Additional Uses

    I have a large stack of lumber behind the shed that's going to be useful for projects not too far in the future. Most of the material (probably 600+ bd ft of it) is far wider than my jointer/thicknesser can handle and I somewhat despise ripping nice wide boards just to be able to machine them flat. They can be processed at a local lumber supplier who has both a large router base flattening rig as well as a wide sander...but at a cost. I actually used that service a couple years ago for a client project as the two slabs I was presented with to do a dining table top as well as a welded base design were way too large to deal with in my shop. (I did the design, but an actual welder made it) So cost nearly $200 just to get them surfaced flat and thicknessed. That's for two pieces of wood and at a "nice guy discount", too. So adding the ability to surface wide stock and slabs to my shop would be a nice thing. Additionally, my new slider is a short stroke machine. It's perfect for the majority of the work I do, but occasionally I do need to rip a full sheet of something and prefer to use the track saw for that. And then there is the "embiggened-assembly" opportunity for things like a big table top. I don't ever want to have to jury rig things like I did a number of years ago with the "kitchen continent" project which required multiple benches for length (and lots of shimming to get them to the same heights) as well as lumber sticks to be able to support something much wider than those benches.

    Hmm...so I "did a thing" and "made a thing" to deal with all three processing opportunities. Solving the first problem of surfacing very large pieces of wood was the crux of the matter since the other two applications could be accommodated easily from the same work surface setup other than planning for easy conversion. A bunch of flattening "systems" are available out there and of course, one can roll their own if they are so inclined, with or without a kit of parts. I had no interest in rolling my own, wasn't impressed with several "lightweight" solutions that also didn't scale well and was somewhat interested in supporting a US based small business. In the end, I chose the system build in Ohio by a small company with a brand named TrueTrac. The setup wasn't chump-change, but the quality is pretty darn good. I had sold a personal item recently that I have not used for several decades and that pretty much funding this shop addition. The support interaction I've had with the company has been very positive. I chose the 48x96 setup with the small handwheel to index laterally for each pass and also added the dust collection hood to that kit. TrueTrac provides a plan for a cutting table that provides the required support and it's easy to make it fully modular so everything can be stored away. This size answered my desire to be able to deal with slabs up to 8' long, table surfaces of the same length and up to 4 feet wide for both assembly and surfacing and, of course, a full sheet of "whatever" that needs to be ripped with the tracksaw.

    Let's start with the support table plan...it's two sections that are 57.5" square for the 4x8 setup.

    IMG_4166.jpg

    To make them, buying 10' lumber was the most efficient in both cost and waste. While the plan only calls for 2x4 based structure, the decision was made to make the outside frames with 2x6 material that would be edge jointed reasonably straight and then thicknessed to 5.25". A little time making shavings would improve the work surface flatness just a bit...it's not perfect, but better than "off the rack" construction lumber! The cross rails would be made from 2x4 material (again, starting with 10' lumber cut in half) and surfaced in the same way to 3.25". I did not bother with the faces as they do not come in contact with the "stuff" that will be processed on the table, but I did carefully choose the two pieces that would be bolted together in the middle to make one table out of two modules.

    At the start...

    IMG_4164.jpg

    After processing...

    IMG_4169.jpg

    Trimming to lengths....

    IMG_4175.jpg

    Sets ready to build two identical frames...

    IMG_4176.jpg

    And now the little bit of fun working those two center cross rails that will bolt together. I actually joined them physically with screws to insure they stayed identical while drilling and cutting.

    IMG_4177.jpg IMG_4178.jpg
    --

    The most expensive tool is the one you buy "cheaply" and often...

  2. #2
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    The whole support structure will be supported by a smaller, simple frame that's suspended between two hefty Kreg horses. That simple frame is made of 2x4 surfaced as able and because the two center cross rails are the taller 5.25" material, some dados needed to be cut to the correct depth so that the simple frame would pass through them and support them. After laying out the boundaries and calculating the depth, the material was chewed away at the table saw.

    IMG_4179.jpg IMG_4180.jpg

    The bottoms of the dados needed to be cleaned out. I started out using just a "sharp" chisel, but this material wasn't cooperating a whole bunch with that, so out came the router. The wood bowed down to the spinning cutter and not only was the bottom clean, it was actually at the correct depth. Go figure...

    IMG_4185.jpg IMG_4186.jpg

    Keeping those last four photos together made sense for the story, but before the nibbling of the dados at the saw, I drilled the three holes for hefty half-inch bolts that would be used to joint the two grid modules together. Drilling them while the two center cross rails were screwed together insure that they would be in the correct place for the surface of each side to be in the same plane with each other.

    IMG_4181.jpg IMG_4182.jpg

    And there you have it...two identical center cross rails

    IMG_4187.jpg

    All the side rails for both modules were clamped together and marked for the cross rails. The spacing ended up being about 11.125" OC, evenly spaced, despite the plan showing them at 11.25". The marking was important to both position the cross rails on the inside of the frames about to be built as well as to mark where construction grade screws would be driven from the outside on the centerline of each.

    IMG_4191.jpg
    Last edited by Jim Becker; 03-09-2023 at 8:44 PM.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
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    Assembly started by laying out the outside frame pieces on the floor. While selecting pieces for each frame, I chose a specific surface for the "top" on each board and those "tops" are "down" on the floor...building this upside down to allow the floor to support the cross rails that are shorter than the side pieces.

    IMG_4193.jpg

    I started in the middle on both sides, using the dados to clamp the side pieces to the ends of the center cross rails and then screwing them in place.

    IMG_4194.jpg

    Corners were also clamped up, but using 90º supports. This doesn't make the whole thing "square", but helps get things moving in that direction.

    IMG_4195.jpg

    A "few" screws later and the frame(s) are put together. Note, I did not bother with glue on these corners as it was end grain to side grain and there would be glue blocks put in later to deal with that.

    IMG_4196.jpg

    Squaring came next. On one side I clamped a 4' level to make that side relatively straight and hold it that way. Longer would have been nicer, but well, I didn't have anything longer that was known straight. It worked fine. Measuring corner to corner of the whole thing (the center cross rails were already bolted together snugly) a little minor "encouragement" got the whole thing pretty darn square.

    IMG_4197.jpg

    Since the the whole thing is "bottoms up" at the moment, I made corner blocks from scrap plywood and glued/screwed them to the...eight...corners so that they would stay square. That was allowed to dry overnight to be sure.

    IMG_4199.jpg
    Last edited by Jim Becker; 03-09-2023 at 8:55 PM.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  4. #4
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    The next day it was time to install the cross rails. Remember, the assembly is top down on the floor so "theoretically" the tops would all line up. Well, concrete floors are not exactly flat even though they look flat. So as I moved from rail to rail, I used various metal rules inserted under the outer frame to match the actual gap to insure that the top of the rail would be in plane with the top of the side piece. This worked very well actually. Each rail got two screws and before you can say "I need another donut", they were all install. Not really. It took longer than that...

    IMG_4203.jpg IMG_4204.jpg

    I stood the whole thing up to free up the space needed to get a first look at how it would be when up on the horses and smaller frame. I didn't have two 2x4s available at that time, so I grabbed a couple of 2x3s that I did have, raised the "holders" on the side of the horses and made ready for the big reveal. 2x3s would be stout enough for the real deal, but they were fine for planning things out.

    IMG_4206.jpg

    And that worked nicely...it was too tall so knocking the horses down lower was indicated, but otherwise, it was moving in the right direction. Boy, that sucker is big! LOL

    IMG_4207.jpg

    The next day, I grabbed a couple of the straightest 2x4x8 I could find at the home center and then surfaced them the same way as the other stock; flattening and then thicknessing to the same 3.35". These were then mounted on the horses, which has been lowered to level "2" and two pieces of stock were put on the ends to make it a big rectangular frame. Those end pieces stabilize things a little and also helped with alignment so that the whole cut table hangs evenly on both the sides and the ends for even weight distribution.

    IMG_4227.jpg

    At this point, the table construction is more or less complete. When I got to the final-final thing, a few screws locked the cut table to the smaller frame and the smaller frame was screwed to the brackets on the horses. I did not do that at this point because I knew it would get moved at least once if not more. Next up...putting the TrueTrac system together.
    Last edited by Jim Becker; 03-09-2023 at 9:09 PM.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  5. #5
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    The TrueTrac Router Gantry system was packaged extremely well with cardboard covers, shrink wrap, foam padding to protect the ends of the aluminum extrusions, delran parts wrapped in paper, etc. I received two boxes; one for the whole router gantry system and one for the optional dust collection setup that will be shown later. The instructions were detailed an easy to follow. All the required hardware was included and that also meant a small allen wrench that was used for most fasteners. There were only two things (that I can remember) that required me to pull out a different size allen wrench. A Phillips head screwdriver was the only other tool required but I did choose to use my t-handle allen wrenches for personal comfort.

    IMG_4228.jpg IMG_4229.jpg

    The router support base is built first from five components...three aluminum and two delran. Everything was machined precisely...and I do mean precisely. Nice brass inserts were already installed in the delran parts.

    IMG_4230.jpg

    I will be using my DeWalt 618 router on this device, at least for the moment. Since I don't really use the D-handle base, I chose that for the router gantry. The handles are not compatible with the position required for the pre-drilled mounting plate (pre-drilled for a whole bunch of different routers), so I removed the handles from the base. It wasn't a hard task and they can easily be reinstalled in the future should I decide to use a different router on the system. With the handles removed, the base is pretty much identical to the fixed based while also would likely have required the handles removed.

    IMG_4231.jpg IMG_4233.jpg

    Next up was assembling the actual gantry...easy peasy, as Jason from Bourbon Moth likes to say. Everything was precisely machined and the 8-32 allen head bolts were very high quality.

    IMG_4238.jpg

    And then it was time to put together the dust collection option...which meant taking a few things apart 'cause I hadn't pre-read the directions for the dust hood which requires eight holes to be drilled and chamfered in the router plate to affix the dust collection option.

    IMG_4188.jpg
    Last edited by Jim Becker; 03-09-2023 at 9:25 PM.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  6. #6
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    I'm looking forward to seeing the finished pics. You'll need to invest in an overhead crane if you keep tackling projects this size!
    Please help support the Creek.


    "It's paradoxical that the idea of living a long life appeals to everyone, but the idea of getting old doesn't appeal to anyone."
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  7. #7
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    The dust collection hood is also very nice quality including two pieces of CNC machines polycarbonate and "hula skirt" sections made with aluminum and whatever the "skirt" comes out of. Turning the router mount upside down so that the bottom of the plate was visible, the polycarbonate pieces were located and I marked the edge where they would be hanging out from the router plate to be able to remove the protective backing. These were then used to locate the eight 11/32" holes that needed to be drilled and chamfered which was done at the drill press with some "creative" workpiece support.

    IMG_4239.jpg IMG_4240.jpg IMG_4241.jpg IMG_4242.jpg

    After that little exercise making curlies of aluminum, the actual assembly of the dust collection hood to the router plate was easy using 8-32 screws and nylon insert nuts.

    IMG_4243.jpg IMG_4244.jpg

    Next up was to assemble the rails that mount on the support table. These are precision aluminum extrusions (custom to the folks at TrueTrac) and join together with typical dovetail slides and set screws to make a nearly 115" long rail for each side of the table.

    IMG_4251.jpg

    I determined that raising the rails 3/4" off the support grid would allow machining of a 3" thick slab or table top and this played well into my plan for multi-use...the rails were mounted on two 1x3 sticks to both raise them as well as provide for an easily removable assembly for supporting alternative uses for the table as well as breaking down for storage. I mounted the rails on those sticks after placing the sticks in the position where they would be at the edge of the table and then using the gantry to actually measure the width between the rails from end to end. Only four screws hole the rails to the sticks but that's all that is required.


    IMG_4250.jpg
    Last edited by Jim Becker; 03-09-2023 at 9:43 PM.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  8. #8
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    Given that the stick and rail components need to be removable for both function and storage, I chose to put threaded inserts into the support structure and use small fixture knobs I had lying around for the deed. A little drilling to locate and install the threaded inserts and the deed was done.

    IMG_4252.jpg IMG_4254.jpg

    And that more or less completed the assembly to build the thing.

    IMG_4255.jpg IMG_4256.jpg

    Did I mention it breaks down?

    IMG_4266.jpg

    As I mentioned in a short addendum to my shop build thread, the reality set in that the large and heavy mobile clamp rack idea, while nice, didn't last long. The floor space it took, while not huge, was a limiting factor in orienting this new setup in a way that I can use it when setup without it interfering with other tools as well as the big door. So the clamps were relocated with the big stuff on the wall and the small stuff on the base of my main bench. I have to walk a little farther for the big clamps, but this is a better solution for me going forward. And it lets me put this flattening/sawing/big-a-assembly setup in a spot that makes sense when it's up.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  9. #9
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    Speaking of which, it was time to reassemble that sucker in said place. So I did. It ever so slightly overhangs the big door, but not enough to matter. It's far enough from the main bench that it will not interfere with that. It far enough from the infeed side of the slider when pulled all the way back to not get in the way and is about a half inch lower (with the rails removed) so there would be no issue with material over hanging if necessary to rip something on the saw that's long. A good spot and if I decide I like it, I'll mark the floor so there's no question about the position.

    So up it went and then I check for twist which is certainly possible with a floor that's not perfectly flat...there is no such thing for the most part. It was about an eight inch out as there is a slight dip in the floor toward the big door. Shimming fixed that.

    IMG_4267.jpg IMG_4268.jpg IMG_4269.jpg

    So we can call this "done for the moment". I'll deal with the overhead dust collection at the same time as I do the extension to the lathe and also will put a power drop from above, too, for convenience. I think I'm going to paint the sides just to make it look more pretty than two-by material.

    IMG_4270.jpg IMG_4272.jpg IMG_4273.jpg

    I'll do a test run soon...I have some CNC work to do for a guy before I can get back to this as of the time of this writing.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  10. #10
    Seems like what you really need is a 4'x8' cnc router.

    It's a bit late in the game, and maybe your router placement would make it impractical, but couldn't you flatten large slabs with your 4'x4' cnc by tiling with some outboard supports for initial levelling? I know from experience that pushing a router sled around by hand gets old fast.

  11. #11
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    Quote Originally Posted by Kevin Jenness View Post
    Seems like what you really need is a 4'x8' cnc router.

    It's a bit late in the game, and maybe your router placement would make it impractical, but couldn't you flatten large slabs with your 4'x4' cnc by tiling with some outboard supports for initial levelling? I know from experience that pushing a router sled around by hand gets old fast.
    I've used the CNC for flatting things that will fit on the ~49x49 table top, but it's not the best solution for bigger things as it's very difficult to shim things up and keep them in an even plane to mill the additional length. There's no financial possibility that I can upgrade to a larger CNC, nor could I justify it as woodworking is an avocation and I rarely do work for others at this point. (I have exactly one "customer" who is more of a friend at this point and it's only a few times a year) In hindsight, the cost to go to a 4x8 at the time I was buying my CNC was only $3K more, but that ship sailed in 2018. This more simplistic solution solves multiple problems for me and was funded with no new out of pocket expense because of selling a watch I had not used for decades. If I was flattening as a business, the solution would be different. But I'm not and I have the time to "enjoy" moving the router manually to accomplish the task. The indexing feature for lateral movement, however, makes for some interesting possibilities for straight cuts along the long axis.
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    The most expensive tool is the one you buy "cheaply" and often...

  12. #12
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    Very interesting build Jim. As with most things I've saw you undertake (probably all) you think the design all the way through and execute it well. Details matter in something like this as well. Thanks for a well documented construction process as well. Even though it isn't something I need it's always a pleasure to see the skills of other in play.

  13. #13
    That is a biggly table! Hope the dust collection is adequate, but maybe not hard to roll it outside.

  14. #14
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    Yea..."Bigly" is a good description! LOL The dust collection will not likely be "great" but it absolutely will be better than none at all. I don't have a flat area to use this outside, but the shop floor is easy to sweep.
    --

    The most expensive tool is the one you buy "cheaply" and often...

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