Workbench retrofit

[Ned Otter]

Hi everyone,

Long ago I purchased a 4" thick, 8' long, hard maple bench top but it's only about 21" wide. I want to glue a new 8' piece of maple to bring it to 24" wide.

However, if we assume the top is flat (at least near the edge), and check it with a square, further down the thickness towards the bottom of the benchtop, it's off (thicker at the bottom).

I want it to be 90 degrees, because the piece I'll be gluing to it will definitely be 90 degrees, and part of it will be used as a clamping surface.

Running through various scenarios on how to accomplish this:

1. Use a router bit with a 2" cutting depth that has a bearing at the top, flip the workbench, and use a router bit with a 2" cutting depth that has a bearing at the bottom.

2. Use a track saw with a really long guide rail (expensive to purchase, and also expensive to ship). Cut to max depth, break off the piece that's been cut, flip the benchtop and follow up with the router bit that has the bottom bearing

3. Move the benchtop to the sliding table saw, cut at max depth. Break off the piece that's been cut, flip the benchtop and follow up with the router bit that has the bottom bearing

I'm inclined to go with option 1, for it's simplicity. Not sure my slider is dialed in to make an 8' cut that's relatively parallel. Also don't want to move this monster slab any more than necessary.

There may be other solutions I'm not considering, please let me know your thoughts --

Thanks,

Ned

[Jamie Buxton]

One more process you might consider is hand planing. The tilted surface is probably not far off 90 degrees, which means you’re not removing much material. Also, the planing job can tolerate some gouges; it is going to get covered by the added maple.

[Greg Parrish]

Couple more ideas:

Couple of strong friends and run it through the jointer a few times?

Track saw cut both sides with careful line up and then either hand plane or 2.5 to 3 inch router bit with roller to smooth the center where the two cuts meet.

[Jamie Buxton]

Rather than an expensive track saw, use a budget equivalent. Fasten your own straightedge to the bench top. Use it as guide for a circular saw. Instead of the usual 7” circular saw, you can acquire a beam saw. In this category, there are big circular saws. Makita’s has a 10” blade. It can crosscut 4x8s in one pass. I’ve seen beam saws with a 20” blade. That 10” Mikita costs $350 brand new. I see the larger saws on Craigslist used for $300 or so.

The Craigslist for San Francisco has four listings for 16" Makita beam saws, for prices from $200 to $350. That won't help the OP in New York, but maybe these saws are as common there.

[Jamie Buxton]

A benefit of the beam saw is that you never have to move that monster slab. And you never have to flip it either. The bench just stands there while you trim the edge of the top. That alone would justify buying the beam saw for me. You can sell it if you’re never going to use it again.

[Monte Milanuk]

Lately I've been on the hand-tool kick, so I'll second that suggestion. However, if you're not set up for and/or practiced at that sort of thing already, it might be more frustration than it's worth.

Might be worth seeing if there's a shop in your area that does slab work - mantles, coffee tables, etc. We have a local place that has a Slab-Mizer that would probably make short work of that kind of job. Not sure what they'd charge, but it might be worth asking. Similarly, if you can find a place with a CNC router that is willing to do a one-off job it might be way faster/easier to just let them do it.

[Ned Otter]

Thanks to all who have replied --

I had already reseach using a beam saw, but had moved away from it as I have no experience with them, but may reconsider.

@Greg - not sure we could keep it at 90* while running through the jointer, might be a lot of grunt work for not such great results.

Appreciate the feedback --

Ned

@Jamie - you are correct, it's not off by too much, will think on it.

[Cameron Wood]

I have a Makita beam saw, & it makes remarkably good cuts, especially crosscut, but it is also heavy, awkward, & huge to store. The rip cut would not be ready to glue.

I'd probably hand plane, or run the top through the table saw & finish with hand plane.

[Ned Otter]

Thanks, Cameron - after further research last night, it seems that unless you get a multi-thousand dollar beam saw (Mafell- level), runout on the Skil and Makita is not that good, so I'm moving away from that. I've got router bits on the way, will see how I fare with that before going further.

[Monte Milanuk]

not sure we could keep it at 90* while running through the jointer

Depending on how you do it, the mating edges don't necessarily need to be perfectly 90 degrees / square, so long as they are complimentary to one another. Lay the boards side by side, edge to edge, then fold them up like a book and clamp them together. Flip it over, and plane the edges smooth together. Flip it back, and unfold. The resulting edges may not be perfectly 90, one may be 89 and the other may be 91, but they'll still match up which is what you actually need.

[Tom Bender]

So the new piece of maple will be 4 x 3 x 96. Do you have it yet, in the shop acclimating? Plenty of clamps? Test clamp it in place to see how it fits, there may be some surprises. You'll want no gaps at the top of course but not be so concerned with the bottom, as long as it's tight on most of the glue surface.

To flatten the edge you might try the 'slab flattening sled' method with a router and an end mill.

[Ned Otter]

So the new piece of maple will be 4 x 3 x 96. Do you have it yet, in the shop acclimating? Plenty of clamps? Test clamp it in place to see how it fits, there may be some surprises. You'll want no gaps at the top of course but not be so concerned with the bottom, as long as it's tight on most of the glue surface.

To flatten the edge you might try the 'slab flattening sled' method with a router and an end mill.

Tom, I've had that maple in my shop acclimating for several weeks now, just jointed and planed it tonight. Will do a dry run to see if I have enough clamps, will likely have to get some more.

I'm not set up for the 'slab flattenting sled' method you describe, unfortunately.

[andrew whicker]

How much vertical movement is there on your router? I would try to use only the top as reference. Start the router on some ply or MDF as a straight edge for your bearing and take only so much off at a time.. lower and repeat. Get rid of the sheet goods when you're ready to run the bearing on the actual table and keep lowering until it's all clean.

https://www.amazon.com/Whiteside-Rou.../dp/B000K2CAO2

$54 isn't a bad investment.

If you had to start out taking less material you can buy the one above and the 1" long version: https://www.amazon.com/Whiteside-Rou...dp/B000HZV5L6/ ($ 38)

[Ned Otter]

Andrew, thanks for your reply --

I just received the bit from the first link you sent yesterday, but with a 4" thick benchtop, it can't get more than about half way, at least in the one router I tried. I have a few different routers I can try with next.

[andrew whicker]

Yeah, duh the collet gets in the way. Wasn't thinking. That's internet advice for you from a random.