Rebate depth?

[Bojam]

I need to route some rebates on picture frames I'm making and these will be 18mm wide. I need to cut to full width and depth in one pass. This is because the frames are narrow - just 30mm - so there won't be enough supporting material left to stabilise the peices for multiple passes.

I have a 19mm straight bit. How deep can I cut at this width in a single pass? I need at least 5-6mm to accomodate the picture and a thin backing board. Deeper would be better if possible. Currently the peices for the frame are 24mm thick but this can be reduced depending on the depth of the rebate.

I intend to do this on the router table before assembling the frames.

Thanks in advance!

 

[Doug B]

It depends on your set up, personally I’d just try it if the routers not coping then you’ll soon tell but with a sharp bit & a decent router you should manage what you’ve said

 

[Inspector]

I cut that kind of thing with the table saw. First cut on the flat and second vertical to meet the first. Fingerboards to control it and push sticks to move the wood over the blade.

Pete

 

[Jones]

If there's not enough material to stabilise for multiple passes it might also be a problem when you get to the end of the cut. You can use double sided tape to stick a strip of timber slightly smaller than the rebate to the table after the cutter.

 

[Bojam]

It depends on your set up, personally I’d just try it if the routers not coping then you’ll soon tell but with a sharp bit & a decent router you should manage what you’ve said

Thanks Doug. I should have mentioned that I have use a Bosch 1600GMF. And the material is Purpleheart, so pretty hard / dense.

 

[Bojam]

I cut that kind of thing with the table saw. First cut on the flat and second vertical to meet the first. Fingerboards to control it and push sticks to move the wood over the blade.

Pete

Cheers Pete. I can see that being easier but I don’t have a table saw so router it is.

 

[Doug71]

If it won't work with one pass for the second pass could you attach a lath the size of the first rebate to the in feed fence to give the wood extra support.

As Jones said above you might also need the same kind of thing on the outfeed fence.

 

[Cirks]

I would have thought with decent bit you’ll be able to do in one pass but unless I misunderstand the dimensions, you could always rout the other way, I.e 5-6 mm cut with multiple depth passes until depth is 18mm. Then you’d have 18-19mm (24-5/6) wood for support on each pass rather than the 12mm (30 wide -18cut) you were worried about

 

[Henniep]

I cut that kind of thing with the table saw. First cut on the flat and second vertical to meet the first. Fingerboards to control it and push sticks to move the wood over the blade.

Pete

Hi inspector - agree, I also use the table saw. Bit dicy working with small pieces of timber on the router.

 

[harryc]

I always find too much tear out with the router hence use the table saw as well.
Maybe I need some new router bits lol.

 

[Sgian Dubh]

You could try a different approach whereby you machine some material up at roughly 65+ mm wide by whatever thickness is needed, work the rebate in multiple passes at both edges, and then rip saw the 65 mm width into two pieces at 30 mm+ wide. This leaves a sawn edge, but if done cleanly three or four passes with a hand plane should remove the saw marks. Alternatively you could set up a simple jig to carry the rebated parts so that the back and front face of the frame are held perpendicular to the bed of a thicknesser to dress them down to 30 mm.

Of course, if you've already dimensioned your material to your required 30 mm width the above suggestions are redundant. Slainte.

 

[Vintage Frames]

As you're trying to rebate a picture frame moulding the thing to do is to chop the moulding oversize by about 100mm, beyond the mitred size.
Now connect the lengths to an equal length PAR board of about 50 x 30mm along the outer wall of the frame moulding. Fix the lengths together at either end with some instant adhesive - mitre fix or other, but only by about 20mm at each end.
Now you can pass the assembly through your router table without any risks.
When done, cut off the timber at each end to release the frame lengths.