11mm dado over 5m. 40 times.

[colinb4987]

In the not too distant future I will need to cut a 10.5/11mm wide dado to a depth of approx 15mm along the length of a 47 x75mm piece of timber, on 40ish pieces of timber.

Edit: sticks are 5m long, dado/groove is on the centreline of the 75mm face, and is to house a 200mm wide strip of 11mm OSB. One stick on either edge of the OSB for a non-load bearing I-joist.

What suggestions do you have on how best (efficient and safe) to do it?

Domestic environment; available power tools are:
OF1010 1/4" router (no cutters)
GOF2000CE 1/2" router (no cutters)
TS55 plunge saw
BS250 bandsaw
Electric chainsaw
Various grinders, reciprocating saws etc etc
Nilfisk vacuum

No router table currently set up; unmounted MFT top available plus a 7ft solid pine beast of a handtool bench with face vice and holdfasts

 

[paulrbarnard]

The chainsaw will do the job but the precision will be low.

Either of the routers will do the job. The ½ inch in a single pass. The ¼ inch might need to go down in a couple passes. It would be possible with just the router fence but improvising a router table would make the job much easier.

 

[Bingy man]

1/2 router with a decent cutter , think I’d do a few trial runs first in a few off cuts . You may do the job quicker and safer if you clamp /screw 2 pieces together to give yourself a wider surface for the router to ride on . Then using the fence you can do 2 edges each time ( up one side and back down the other ) of course any screws/ bolts could be positioned outside of the length you req and below the cutting depth of the router if you see what I mean ..

 

[MikeJhn]

From purely a time factor view I would buy a cheap router table: Lumberjack RT1500 1500W Bench Top Router Table with Integrated Router 5060429093170 | eBay

 

[Adam W.]

1/2" shank side entry rebate/slot cutter with bearing sized to your rebate dimensions in the big router.

Set it up and whip along the timber with it clamped to 3 good, sturdy trestles.

 

[ColinDeVelen]

Maybe I missed it, but if the pieces are 47 × 75 profile, how long are they? You say you want to cut the dado lengthwise, so this is more of a groove than a dado no? If they are less than a couple of feet, probably an improvised router table would do fine, clamped to the end of the work bench. If they are longer, then a couple of bracing pieces on the workbench, and a fence or two on the larger router.

 

[colinb4987]

1/2" shank side entry rebate/slot cutter with bearing sized to your rebate dimensions in the big router.

Set it up and whip along the timber with it clamped to 3 good, sturdy trestles.

You had me puzzled there for a minute, until I re-read my post and realised I hadn't actually been clear that the dado runs down the centreline of the timber on the wide (75mm) face. Main post edited for clarity....

I guess that rules out bearing guided cutters and puts me in the realm of a router table of sorts?

Could I fit an 11mm diameter bit to the big router, poke it through a hole in the bench or MFT, secure router to underside of bench/MFT, and clamp a nice long fence (timber?) to give me the right offset? Add feather boards or secondary fence to keep the timber centred over the cutter, and run the sticks through

 

[colinb4987]

Maybe I missed it, but if the pieces are 47 × 75 profile, how long are they? You say you want to cut the dado lengthwise, so this is more of a groove than a dado no? If they are less than a couple of feet, probably an improvised router table would do fine, clamped to the end of the work bench. If they are longer, then a couple of bracing pieces on the workbench, and a fence or two on the larger router.

They're 5m long, trench/groove/dado/slot (what is the difference?!) Is on the centreline of the 65mm fave

 

[Adam W.]

Oh.

Up cut spiral bit in the big router with a fence on it or on the track if you have such a long shiny thing. Or your track saw, but that will take time.

 

[colinb4987]

The chainsaw will do the job but the precision will be low.

Either of the routers will do the job. The ½ inch in a single pass. The ¼ inch might need to go down in a couple passes. It would be possible with just the router fence but improvising a router table would make the job much easier.

Chainsaw it is then! Perhaps not...

1/2" and an improvised table sounds more and more like the option that is most readily achievable

 

[colinb4987]

Oh.

Up cut spiral bit in the big router with a fence on it or on the track if you have such a long shiny thing. Or your track saw, but that will take time.

I definitely do not have such a long shiny thing, and my wallet shudders at how much I'd have to fork out to make one!

Will look at what the fence situation is for the big router. Would the little router be up to it do you think?

 

[Samkilby]

One thing that will really speed this kind of work along will be getting the right router bit.. either a 2 flute with replaceable knifes or a spiral upcut, or the slot cutter someone else has put above.
Ideally you want to cut to the correct width in one pass.. depends how tight and “fitted” the osb needs to be really. Osb by its very nature is slightly variable thickness, but you could for example use pu glue and make it a not grippy fit ( but make sure you mask up with parcel style tape before as it really foams out !)
The reason you don’t want to be doing 2 passes is because with so many bits to do, you might not take full care over the processing of the timber, so if there is any inconsistency in the dimensions you will end up with bigger and smaller grooves.. if you set the fence on one bit that’s 74, another bit is 76 then two passes off opposite faces will ruin your life.
Similar if you buy all the timber park from a builders merchants etc..
and you don’t want to process it all like several passes for depth, reset fence, several passes for depth. Maybe you could use a smaller bit (6-10mm) and use a spacer block on the router fence for a second pass for width ?
But yeah router table will likely be more accurate and faster. Or make your rudimentary router table.. but poking it though a workbench might be a pita and you may run into clearance/bit depth issues..
if you had access a spindle moulder would be the winner. Maybe try and make friends with a local joinery or furniture shop and offer them £50 to do it yourself on their kit ? Gotta be worth it for the time saving and repeatability..

 

[ColinDeVelen]

Personally, in my workshop I barely have space for 5m lengths of anything (except string or tape), never mind the space to pass 5m lengths across a router table. At that length, you would also want infeed and outfeed support.
Personally, when I am grooving something long like that, I would use both routers. One has a larger bit in it for getting most of the waste out, in the big router, with a double fence to center it on the workpiece (may need several passes to get to depth. Smaller one is used to finish to the correct distance from each edge, single fence. Go up one side and down the other. Only a single pass for each side, as you would be cutting with the edge of the cutter, not the bottom.

 

[dzj]

+1 for the double fence.

 

[Jones]

Simply buy ready made I beams. Probably cheaper, certainly quicker and they'll look better.

 

[clogs]

think I'd just get a used spindle moulder and hang the expence....for safety reasons....and future projects..
if he has to ask that kind of question there's danger afoot.....sorry.....
OR
just pay a joiners shop to do it, prob just a few quid during lunch for the lads T fund....
I can see it all going wrong.....
short lengths no prob but 5m....!!!!!!!!

 

[colinb4987]

Simply buy ready made I beams. Probably cheaper, certainly quicker and they'll look better.

Got a source? I could only find trade only suppliers

Looks don't matter, these will be completely hidden. Will make a different thread, to give more details

 

[colinb4987]

Personally, in my workshop I barely have space for 5m lengths of anything (except string or tape), never mind the space to pass 5m lengths across a router table. At that length, you would also want infeed and outfeed support.
Personally, when I am grooving something long like that, I would use both routers. One has a larger bit in it for getting most of the waste out, in the big router, with a double fence to center it on the workpiece (may need several passes to get to depth. Smaller one is used to finish to the correct distance from each edge, single fence. Go up one side and down the other. Only a single pass for each side, as you would be cutting with the edge of the cutter, not the bottom.

Workshop?! What's one of those. I literally don't have a shed ATM, so everything is either in the cellar, under tarpaulins, or in a rickety shack, itself covered in a tarpaulin. Short of not having tarpaulin at all, it's about as far from ideal as possible.

Will take the double fence and two bits idea onboard, thanks

 

[colinb4987]

think I'd just get a used spindle moulder and hang the expence....for safety reasons....and future projects..
if he has to ask that kind of question there's danger afoot.....sorry.....
OR
just pay a joiners shop to do it, prob just a few quid during lunch for the lads T fund....
I can see it all going wrong.....
short lengths no prob but 5m....!!!!!!!!

No space for a spindle, nor the cash

Surely better to ask questions and canvas opinions rather than blunder on blindly and probably more dangerously?

Joiners shop is on the radar now, I'll start looking

 

[Alistairmckinnon1961]

I’ve done this many times to create 12 to 16 mm wide slots (10mm deep) centred on 45x45 timbers. Their use was to create framing to enclose weatherboard/cladding, to produce decorative panels for garden structures like gazebos .
My first solution was 2 full length cuts with a table saw then chisel out. That was slow but accurate.

2nd was table saw then router to clear out slot. Just as accurate but Quicker

3rd was straight to the router (1/4, handheld), quickest, but not quite as accurate (long lengths with hand held)

I’d definitely recommend the router either set up in a table (but it’s space intensive), or handheld but with a double guide fence.