# Trying to use Router to make box joints



## aideym (20 Nov 2012)

Hi, I knocked up a jig to make box joints using a 1/2" cutter. I haven't tried making box joints before but a space in my workstation was begging for a drawer and I thought it would be an excellent opportunity to try.

The problem is that the router is ripping the hell out of the wood and not leaving lovely squared edges I was hoping for. I tried it on plywood and pine and even tried a brand new router bit just in case the others were too dull. It was so bad in parts that some of the fingers were completely destroyed. 

So could anyone give me a clue how to at least get on the right track.


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## mailee (20 Nov 2012)

Sandwich the piece in between two pieces of scrap and that will solve the problem. HTH. :wink:


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## aideym (20 Nov 2012)

mailee":3na5gwag said:


> Sandwich the piece in between two pieces of scrap and that will solve the problem. HTH. :wink:



I will try this but wondered why I couldn't do it and others could.


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## mailee (20 Nov 2012)

it does depend on the wood your using and can sometimes help by using a spiral up cutter. :wink:


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## MickCheese (21 Nov 2012)

I use a 6mm up spiral bit and it works well. 

Is a cutter twice that size asking too much assuming you are doing this in one pass?

Mick


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## Eric The Viking (21 Nov 2012)

I've recently spent ages designing a jig to do box joints for octagons. It turned out to be far harder than it looks, and the results work (the joints fit), but they're not as spot-on as I hoped.

The problem you're having comes from what the cutter is doing as it enters and exits the wood. At those points, the cutter is 'clawing' at the wood (for want of a better description), pulling or pushing fibres out of the surface. The damage at the front of the workpiece is taken away as the cutter progresses (mainly), but as it leaves the work, the last thing the cutter does is pull at the face of the piece. 

In most of the home made jig designs I've seen, because the cutter makes its own exit slot, it's very well aligned with the workpiece, and the fibres are well supported right to the edge of the 'tongue'. You'll still get tearout on the outer face (the one that you start the cut on), to the back of the jig, where the cutter blades leave the wood as the cut starts.

I do mine with 1/4" cutters, and I'm getting a lot of tearout/splintering with cheap deal. I'd guess that a sacrificial piece on the front would almost eliminate it. I think 1/4" is probably worse for this than 1/2", because of the speed of the cutter tips (the smaller ones are slower but have more torque, so they have more tendency to pull at the wood rather than cut it (like a planer's feed rollers).

It's also important to cut in the correct direction, as I found to my cost. The reason the "fence and peg" jigs are pushed right-to-left across the router table is so that the cutter's sideways force pushes the workpiece against the indexing peg. 

If you build it to go the other way, you just wreck the workpiece, as the forces involved are surprisingly strong. Even though you can apply force against the cutter, it vibrates as each knife edge hits the wood, and the effect is a rough and untidy hole (at best). This applies to the first slot you cut, mainly, as that's the one where the workpiece can move. As long as the jig and peg are robust, subsequent slots shouldn't be as bad, as the peg indexes them both ways - the workpiece (theoretically) can't move.

But of course that first slot is crucial. If it's untidy, the next slot will be too, as the work can bounce about on the indexing peg, and the slot after that will tend to be as bad, and so on.

For octagons, it's worse. I find that I *do* need to cut in both directions, and I found I had to add an 8mm bolt to the left-hand fence (the one with the cutter going the 'wrong' way), at cutter height, and just in front of the fence (parallel to it, at the bottom). It clamps the work tight against the peg, for that crucial first notch. To be honest, both ends of the jig (left and right) would benefit from this.

For right-angled box joints, and a quiet life, definitely build the jig to cut right-to-left, and don't attempt to be a hero - leave enough room on the vertical fence to be able to clamp the workpiece very securely - handheld isn't enough in my experience, even if you can get a really good (and safe) grip. Incidentally, going t'other way, it was tearing, even *with* good clamping and a brand new cutter.

Sorry - waffling as usual!

E.

PS: (wot, more??!? Ed.) If you're getting tearout on the end grain at the 'bottom' of the slots, have a close look at the end of the cutter, for resin build up, or just the wrong profile. Trend's 1/4" two-flute cutters have a slightly acute angle on the bottom (if you plunged them you'd get a dome at the bottom of the hole), and I think that's been part of the cause of the tearout I've been getting, but the geometry for the octagonal system is a bit less easy to diagnose. 

Wealden make three-bladed cutters, with the third blade in the middle of the end. They're designed to plunge better and give a cleaner bottom on plunge-cut slots, and I think they help to stop the side cutters scuffing as much too (or clean up after them). I haven't got one in 1/4" (not sure they're made), but they do them in 1/2". The one I do have gives a great finish, although it's been a bit knackered by too much use in laminate-finished boards.


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## aideym (21 Nov 2012)

Thanks for the reply. I didn't consider going right to left. It just didn't cross my mind and I will give it a try. I am using a 1/4" shank so perhaps this combination is the cause of my woes.
I have a morning to myself before starting nights so I will give it a try and use a sacrificial piece as well just to see what works. It just looked so easy on the youtubes and I made it so difficult.


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## Eric The Viking (22 Nov 2012)

I nearly went nuts doing the octagonal thing. 

I've half-documented it to write-up here, but I'm still not getting good enough results to be happy - a new jig will be the eventual result, I think. 

You may be right about the cutter. As you say a sacrificial piece on the front and going right-to-left (with the peg at the back, away from you) is the key to it. Vibration is just one of your enemies!

Hope it goes well.

E.


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## mseries (22 Nov 2012)

I have just made a 3/8" Box Joint Jig based on Steve Maskery's one. It works well, some tear out which i think a sacrificial piece will cure. If not I'll leave the stop 1/8" over thick and plane it down once the joint is cut. As in all my projects parts were re-used from something else, this time some old contiboard furniture (about 30 years old) and my previous jig that got broken when I moved workshops. In summary, looking at the fence the tooth is to the left of the cutter and the stock moves from right to left as I cut each slot. The stock is clamped to the fence with G clamp (my non screw clamps vibrated and allowed movement).I push the whole jig over the cutter from behind and clean the waste out between each cut.


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## aideym (23 Nov 2012)

The sacrificial wood worked a treat and I was able to make a passable first attempt at a drawer. Thank you for the help, it was appreciated.


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## devonwoody (23 Nov 2012)

My pennyworth added to the good tips above is to clamp the timber to the fence and not rely on holding by hand on those jigs.


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