take lots of material for a lap joint - Best way?

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rokosz

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I've got 4 timbers 2 3/4" thick I want/need to take 5 1/2" inches off each of the ends for 90 deg. lap joints.

I've come up with free-handing a router (with appropriate support around the 3 outsides), while fencing/being really careful on that inside line. I've never fenced for this kind of cut but don't picture it being tough.

Or, thought, maybe router table. But that will only get me 4" of the 5 and I wasn't relishing muscling the butt end of the 75" long timber against the table fence. Nor am I buying or making a larger table.

I'm expecting to use a 20mm or a 3/4" straight bit cause that's the biggest I got.

So any other way without purchasing a multi-hundred dollar tool? I don't mind a simple tool/accessory if it makes the effort more secure.

Regarding the lap joint. I paid a man to make some storms and screen frames. I can dream of having that fine a result. Shame I had to paint them. Anyway, I noticed that he used lap joints -- and that they weren't 50:50. Is there good reason to go off center (like 1" 1/4 : 1" 1/2, 60:40 or something)? Would that depend on what the timbers are containing inside the 90? In this case its 3/4" set in a 1/4" deep straight rout down the center.

Sincere thanks for your experience and wisdom.
 

bud16415

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I have made some where I set my skill saw to depth and made cuts across the lumber every quarter inch or so. The only one that really has to be good is the shoulder cut. Once I made all the cuts I knock off the fins with a hammer and then finish the face with a flat chisel.
 

Steve123

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Moving the router over the stationary board should work. Hopefully you have not cut the boards to final length yet, so you can leave an inch at the end at full height, just for router support. You might want to replace your router base with say, a 12" x 12" x 1/2" base plate for better support.
 

rokosz

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thank you bud and Steve.
chiseling? I presume a more accomplished woodworker could get that nice, smooth and level/square. But I think I'd end up proving my second greatest woodworking skill (making chips). My first greatest skill is making sawdust.
Nope the boards are cut to the proper length (75 7/8") and I've got quite a few larger (12") pieces cut from them that allow me to wrap 3 around the end allowing me to center the butt end.
I'm picturing the first rout to take a an inch or so of those bracing pieces around the desired cut and after that just incidentally more as each lap is cut. I presume in a pinch I could flip the brace pieces over too.
The router table is flat enough to keep all four pieces level with each other and I've got 15ft ratchet tie downs for keeping things tight, which will probably wrap around the entire board/brace perimeter -- but maybe the two outside braces will slip inside the loop. I'm glad I've got lots of extra pieces being such an amateur, I've done many test cuts and kerfs. I'm hoping my patience and plodding will be rewarded.
Steve123, how does a 12x12x1/2 base help support? because its so wide relative to the cutter it helps keep the tool flat? 1/2" thick? it attaches to the router?
Since I'm taking 1 3/8" I'm wondering if that extra 1/2" of depth will cause the bit to not reach my needed depth. The bits I've got are about 2 1/4" total length. not a lot of shank left. Unless I'm really missing on the role of the base plate.
 
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