Squaring a mortice

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I am not much good at woodwork.

When fitting a mortice lock, I bore out for the case with a spade bit, them square it off with a chisel.

I find it difficult to square off the end of the hole, and end up raking it with the chisel to scrape it away.

I don't do it often enough to need a router. Or swan-neck mortice chisels at high prices.

How might I do it quicker or better? Some of my doors need horizontal sashlocks which are very deep, but more often 65mm.
 
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Being a DIYer I also don't have a router, but I use a drill, then a multi-cutter with a fine blade to cut a square, and only then the chisel.
 
You are doing it right, but perhaps use a decent Forstner bit to keep control as spade bits are an abomination. Use a smaller, sharper chisel as it takes less effort and so is easier to control?
 
I'd use an auger type bit myself. Forstners are fine, but can be a but tricky to start freehand. Definitely not a spade bit. They're crude for accurate work. Mark the depth on the bit and drill the holes as near together as possible. Clean out with a sharp chisel as said. That's really sharp. Like a razor.
 
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Well to play devil's advocate here.... I've done a lot of locks with spade bits, but cheap Chinese ones are the real abomination because they aren't sharp and they can't be sharpened. If you use a decent spade bit with a plain point as opposed to those ghastly Bosch jobbies with the threaded points (I mean one such as an Irwin or Bahco), it is possible to control the cut with a degree of accuracy. You do need to be competent with a drill, though, as the bit can exit through the side of the door if you are inattentive or just plain cack-handed. The same is true of 3D bits, except for the fact that they'll go out of line even faster. Forstner bits are also a really bad choice. For some reason the myth persists on thr 'net that you use them for any accurate hole. You do not. They are specifically designed to produce clean flat-bottomed shallow holes (i.e accurate in depth) for shallow recessed hardware such as flush bolts, sash pulleys, gib door hinges and Perko closer plates, etc. Used for deep drilling they are slow, tend to clog easily, can overheat and blue if run at too high a speed and tend to wander off line far too easily (on deep drillings) - presumably why someone used the design as a basis for the 3D bit. The cheap Chinese ones sold by the likes of Toolstation are in any case blunt to start with and just generally dreadful - decent Forstner aren't really cheap at all. So the best solution, as proffered by Dave, really is the good old auger bit (but not the hopped-up super stubby augers offered by Irwin, Armeg or others - they can be just as bad as the 3D bits in the way they behave) - ideally run at a low speed and withdrawn periodically to clear out the chips. Speed is the real killer when it comes to accuracy. Even more controllable if used in a brace.... Anyone wanting to use a router will need deep pockets: the Trend jig isn't cheap, it really needs a 1/2in plunge router with 1800 watts or more of power and the deep pocket cutters don't come cheap, either. If you aren't a die hard router user the thought of using a cutter which projects 70mm or more out of the bottom of the router should also give you the willies. So one for the trade lads doing multiples I'd say although deeper locks still require a bit of extra drilling with a spade bit and cleaning out with a chisel for that last 5 to 10mm of depth

As to the ends of the mortise some modern locks let you leave the mortise ends round. If not you can square them out with a chisel. I have a couple of registered mortise chisels at 5/8in and 3/4in to do this as most locks seem to be in those sizes and they really can clean out the ends of a mortise with 3 or 4 blows of a hammer - at least in chipboard core fire doors. A DIYer might find a 3/8in or so bevel edge chisel in 2 or 3 passes just as useful not to mention cheaper. Not as accurate or fast, though, however absolute neatness doesn't matter too much for the lock body mortise ends because after all they will never be seen
 
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Would the souber DBB mortiser not save a lot of faffing around with forstners, Chinese spade bits, routers etc?
 
Probably it would but it costs more than I had in mind.

Not as expensive as a router, but then, not as versatile either.
 
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Would the souber DBB mortiser not save a lot of faffing around with forstners, Chinese spade bits, routers etc?
They do. Really quick and accurate enough (still leave a round end mortise though) and very good for multiples or singles - but as John says they aren't cheap either (£120 or so with a few cutters). Great for doing multiples and have the major advantage of self-centring on the door (something router jigs don't do). A trade type tool which partly deskills the job although you still need to form the keyholes and other side escapements correctly and you still need a sharp chisel to clean out the the face plate recess corners
 
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A set of Lie Neilson mortise chisels is nearly £300 quid.:LOL:
 
For what it's worth, I think I've done nearly all the ones I have done using a brace and auger bit and an ordinary bevel edge chisel or firmer chisel depending on what was to hand. A brace for the reasons given by J & K. Controllability. I never thought it was particularly hard work, or time consuming. I wouldn't bother with a jig or special machine unless I had to do a lot all the same.
 
Thanks for all the tips!

I have a multicutter so will try that for squaring the sides, though the blades aren't very long.

I also have a brace, though I don't know that I will be any worse with spades. I'm much more practiced with a drill.

I suppose I might go for a jig in the unlikely event that I ever need to do several in one year.
 
A set of Lie Neilson mortise chisels is nearly £300 quid.:LOL:
Far better to buy British and get yourself just TWO registered mortise chisels in 16 and 19mm (5/8 and 3/4in) sizes as they will cover 90% of the lock body mortises you'll see in a lifetime and will cost less than even a basic Souber DBB set let alone those overpriced American chisels.
 
I have a multicutter so will try that for squaring the sides, though the blades aren't very long.
Believe it or not a sharp 38mm (1-1/2in) chisel would be a far better choice - easier to control, better results and it will reach the bottom of a lock mortise as well

I suppose I might go for a jig in the unlikely event that I ever need to do several in one year
Unless you are doing multiples they actually confer no advantages in time over manual techniques - assuming that you have the skills to use them (and sharp tools of the appropriate quality). That wasn't meant to sound cocky, but for one offs power tools can be just a faster way to screw things up.....
 
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I have a set of bevel-edged chisels, and very rarely use them for opening paint tins. I am not skilled at sharpening them, though.
 
I have a set of bevel-edged chisels, and very rarely use them for opening paint tins. I am not skilled at sharpening them, though.
Really, if you are doing woodwork you'd do well to spend a bit of time learning how to sharpen the tools. There are plenty of "how tos" online. It makes it much easier, safer, and more enjoyable.
 

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