rebate cutters

[L Harding]

Quick question...

Anyone know of somewhere that sells rebate cutters like this...

that will cut more than a 1/2 (12.7mm) wide rebate? (I.e. the 'H' measurement)

Cheers

Luke

 

[L Harding]

Also why didnt that work?

 

[Chems]

Thats the link to the page, the link to the image:

http://www.axminster.co.uk//images/prod ... 317_xl.jpg

Try here:

http://www.wealdentool.com/acatalog/Rebate_8.html

bit cheaper (see what I did there, bit cheaper. I lol'ed)

 

[PAC1]

Have you tried Wealdon. They usually solve 99% of all router cutter questions

 

[L Harding]

"lol'ed" HA!

 

[cerdeira]

hi.

is it just me or has anybody else experienced terrible tear out with this kind of cutters (or any straight cutter while rebating, for that matter)?

I resorted to doing a climb cut pass before the final one, but that is not always practical specially on long boards.

what am i doing wrong? I've found that the feed rate has some influence but does not eliminate the risk of tear out.

I reckon that spindle moulders use rebating blocks with spur cutters to avoid the problem, but, speaking for myself, can't justify the purchase of a SM to do rebates...

thanks.

 

[Benchwayze]

Luke,

That looks to me as if it will cut 1/2" rebates.

If you have a cutter that cuts too wide a rebate, just stick plywood shims on the workpiece with double-sided tape, for the bearing to run against. Try-out on scrap until you find the right thickness of shim.

If your cutter cuts too small a rebate, buy a set of graduated bearings to widen the cut until it suits.

HTH

Regards

John

 

[OPJ]

If you're doing this on a router table (?), Weladen also sell large Tenon Cutters. They're not cheap but they're bloody awesome. I used mine for rebating all the time (even though I also have a bearing-guided set) because the finish is excellent and there's rarely any breakout at all (unless you're feeding too fast).

You can also use this in a hand-held router with a guide fence but, that should only be done with the router set on low speed! :shock:

Also, if you wanted to rebate curved rails, you could make a pretty simple 'point fence' (same principles as a spindle moulder ring fence) for a table-mounted router. You're right about the spindle moulder blocks, too.

 

[ColeyS1]

is it just me or has anybody else experienced terrible tear out with this kind of cutters (or any straight cutter while rebating, for that matter)?

Cerdeira, you could always use a marking guage to scribe a line to start with. Pain in the backside, but might help a little if you've only a short run to do.

Simon

 

[Tim Nott]

I had to do some curved rebates for a window frame and bougtht this from Waelden
http://www.wealdentool.com/cgi-bin/sh00 ... 17_2d1_2f2

It is VERY scary even in a router table. Had to take it little by little - next time I'll by a set of decreasingly sized bearings
Whover was talking about tearing out, we get it a lot on the spindle moulder rebating oak for door and widow frames. New cutter inserts and scribing cutters - still ragged.

 

[ColeyS1]

Hi Tim. Seems strange you're getting tear out with new cutters and scribers. I know theres no adjustment with the scribers, but usually the cutters have a little slop on the pins for up and down adjustment. Could it be the cutters are a little too high in the block ? :-k - just a thought. Never had any problems with a rebating block, only when i put a cutter in a little high.

Simon

 

[Eric The Viking]

I had to do some curved rebates for a window frame and bougtht this from Waelden
http://www.wealdentool.com/cgi-bin/sh00 ... 17_2d1_2f2

It is VERY scary even in a router table. Had to take it little by little - next time I'll by a set of decreasingly sized bearings
Whover was talking about tearing out, we get it a lot on the spindle moulder rebating oak for door and widow frames. New cutter inserts and scribing cutters - still ragged.

I'm also doing a window frame at the moment, well a casement.

Wealden were out of stock of the rebate cutter I wanted, so I ended up with this: It's huge, scary and very sharp, and leaves a finish almost too smooth for the tenon sides I'm using it for (cleanup of the actual shoulders with a plane, obviously), but it works a treat for dimensioning. Used in a T11 on speed '2'.

It's no good for the rebates though, so, being in a rush, I stuck in a worktop cutter bought as a bargain bin deal at Axminster recently. Eldest offspring had volunteered to help, so was boringly primed in the ways of dad's table (he claimed experience of routers from D+T at school).

Anyway, the result was lots of tearout (Idigbo). Son was rather upset, so we did some controlled experiments together to find out why.

I can't say if this is generally applicable, but what we found was this:

1. The height of cut (along the axis of the router cutter) doesn't especially matter.

2. The depth of cut doesn't matter as such.

3. The speed of the cutter makes a small difference: faster is better, as long as the feed speed is enough to avoid burning. Bigger cutters have to be slower as a result.

4. The huge difference is the angle of exit of the cutter from the wood. The nearer it is to parallel to the surface, the less tearout. Thus if you try to use a worktop cutter (as we did), to do, say, 18mm x 4mm deep, it makes a mess. If you use the same cutter to do only 1.5 or 2mm, it is much cleaner (all other things being equal).

So I think I've learned why big rebate cutters work so well - the trick is in their diameter. The blades are exiting at a much shallower angle than, say a standard 1/2" worktop cutter, and there's far less tearout as a consequence. As another aside, I see the same effect with a 4mm biscuit cutter in the router too - results for the smaller biscuits are cleaner than the #20 size, as the exit angle is less steep. The cutter is much smaller than those in proper biscuit joiners, so the effect is more pronounced.

Of course, if there's tearout from the finished surfaces (rather than the edge), that's probably one of three other issues (but I'm guessing here): cutter speed being too slow (or feed too fast), so that it pulls grain rather than pares it, cutter blades being blunt or clogged with resin, or bearings going/cutter set too high in the router collet, allowing judder. You'd hear most of these though in the note of the machine.

I must stress I'm a very amateur user, not a pro, and an expert will be along in a minute to put me straight, I expect.

The moulder issue is interesting. I thought the rotational speeds were similar to routers (up to around 20,000 RPM). With bigger cutters, you'd thus expect good results. Do you do oak in one pass, and if so how deep (usually), compared to the cutter diameter?

 

[Tim Nott]

Hi Tim. Seems strange you're getting tear out with new cutters and scribers. I know theres no adjustment with the scribers, but usually the cutters have a little slop on the pins for up and down adjustment. Could it be the cutters are a little too high in the block ? :-k - just a thought. Never had any problems with a rebating block, only when i put a cutter in a little high.

Simon

Good suggestion, Simon
That would stop the scriber doing its thing properly, would it not.
I've just looked at the block and as you say there is a bit of up-and-down play on the cutters and it seems, after squinting a it with a height gauge, it's possible to get the ends of the cutters about .5mm above the scribe. Will do some experimenting this weekend. Thanks a lot.