Making a box then cutting the lid off

[gasman]

Can I ask how most people separate the lid from the body of a box after glueing up. I'm making a large box about 450 x 360 and need to make it in one piece. I would love to take the minimum possible out of where I cut it. I do have a 1.8mm kerf table saw blade but what do others use? Too big for my bandsaw - would I trust myself to handcut it??
Thanks for any advice
mark

 

[bugbear]

Can I ask how most people separate the lid from the body of a box after glueing up. I'm making a large box about 450 x 360 and need to make it in one piece. I would love to take the minimum possible out of where I cut it. I do have a 1.8mm kerf table saw blade but what do others use? Too big for my bandsaw - would I trust myself to handcut it??
Thanks for any advice
mark

A lot of people use a table saw.

Handtool methods:

If you're good, you could use a handsaw. Many texts recommend marking TWO lines for this, sawing between the lines, then cleaning up to those lines.

Alternatively, you could use a plough plane with a fine (probably 1/8") blade.

BugBear

 

[AndyT]

Like BB said.

Try it - it's scary but easier the second time.

Holding a box still to saw it can be awkward - you will need to wedge the saw cuts on the sides you have done to avoid pinching the kerf and splitting the wood.

 

[baldpate]

Depending on how deep the lid is to be, another possible machine method is to use a fine grooving bit in a router table. The box is placed lid down on the table, and each side in turn is run against the fence, which is set so that the cutter just fails to penetrate all the way through the sides (thus leaving all four sides with just enough support that you don't need to wedge). Final parting is done with a knife or fine saw, and cleaned up with a plane.

 

[memzey]

Plunge saw with a guide rail?

 

[Ian]

I always use the bandsaw providing the box is not any deeper than 300mm. It is one of the safest and quickest methods.

I use a carbide tipped blade and it lasts a very long time otherwise a fastcut from tuffsaws does the trick.

Ian

 

[marcros]

Table saw when I had one. If I had a box to do whilst I have no operational table saw, I would probably either find somebody with one or would use the router table and a 1/8" cutter.

 

[Glynne]

Router table with a specific slitting cutter from Wealden's

 

[Baldhead]

Depending on how deep the lid is to be, another possible machine method is to use a fine grooving bit in a router table. The box is placed lid down on the table, and each side in turn is run against the fence, which is set so that the cutter just fails to penetrate all the way through the sides (thus leaving all four sides with just enough support that you don't need to wedge). Final parting is done with a knife or fine saw, and cleaned up with a plane.

I use a similar method, only I don't use the router table (mines a cheapo) I believe Dodge (Roger Berwick) uses this method too.

BH

 

[custard]

Another vote for the router table.

However, I tend to use a small straight cutter bit (2 or 3mm) and aim to work around the lid leaving a tiny sliver of wood still connecting the lid to the box, maybe 0.5mm or about 1/64" thick. I'll use an offcut that's the same thickness as the box walls to set up for this cut, it's very simple to progressively crank up the router bit until you're almost but not quite cutting right through.

Then I'll trim through this final wafer thin layer by hand with a sharp knife and then bring the edges back to dead flat with abrasive paper stuck down to an MDF board.

The benefit of leaving this thin sliver is because the last thing you want is the lid flapping around for the final section of the cut, which is exactly what happens if you attempt to cut all the way through in one go.

This is the method that Andrew Crawford used to recommend. I believe he now cuts the lids off on a bandsaw, but he angles the box as it passes through the bandsaw so it first engages a corner, plus he uses a very tall auxilliary fence. I think his reasoning is mainly to speed up the process during his short courses rather than a decision based on quality. However, unless you've got a very big bandsaw a very big fence and plenty of experience I'd strongly recommend you stick to the method I outlined. It takes longer, but it dramatically reduces the chances for a disastrous miss cut.

 

[Phil Sewell]

I use a router table with a slitting saw from Wealdons (1.5mm I think). I go through on 2 opposite sides, plug the groove width with a suitable thickness shim and put masking tape on the shimmed sides before doing the final 2 sides. Quicker than leaving some material to remove by hand and so far I haven't had any mishaps with this technique. My router table is a spindle moulder I removed the spindle from and mounted a router onto so it's a very solid machine, the fence is the moulder fence so again very rigid. I always make the dovetails wider where the split will be to allow for the material being removed by the router cutter.

For a fool proof method probably a good idea to leave some box wall on to saw off with a handsaw as mentioned earlier. I have used a handsaw to cut the whole lid off but it's a bit laborious.
P.

 

[gasman]

Many thanks everyone - I will have a look at that wealden cutter - I wondered if there might be one. Bandsaw is out as its too big so I reckon I am left with handsaw or router. Brilliant to get such a comprehensive set of replies
Cheers
mark

 

[AndyT]

We do seem to have recommended every possible technique!

Just one more to stir into the mix -another hand tool option - somewhere on here there was a discussion about a slitting plane . it was fenced, like a plough, but had a very narrow cutter made from one or two teeth from a big bandsaw blade. Sorry but I can't find the discussion just now.

 

[Benchwayze]

Another vote for the router table.

However, I tend to use a small straight cutter bit (2 or 3mm) and aim to work around the lid leaving a tiny sliver of wood still connecting the lid to the box, maybe 0.5mm or about 1/64" thick. I'll use an offcut that's the same thickness as the box walls to set up for this cut, it's very simple to progressively crank up the router bit until you're almost but not quite cutting right through.

Then I'll trim through this final wafer thin layer by hand with a sharp knife and then bring the edges back to dead flat with abrasive paper stuck down to an MDF board.

The benefit of leaving this thin sliver is because the last thing you want is the lid flapping around for the final section of the cut, which is exactly what happens if you attempt to cut all the way through in one go.

This is the method that Andrew Crawford used to recommend. I believe he now cuts the lids off on a bandsaw, but he angles the box as it passes through the bandsaw so it first engages a corner, plus he uses a very tall auxilliary fence. I think his reasoning is mainly to speed up the process during his short courses rather than a decision based on quality. However, unless you've got a very big bandsaw a very big fence and plenty of experience I'd strongly recommend you stick to the method I outlined. It takes longer, but it dramatically reduces the chances for a disastrous miss cut.

Gasman
Agree entirely, but by Hand: ,

In your shoes, I would make a full size copy of the intended project in cheap softwood. Jointed with nails or screws, and practice once or twice with a sharp tenon saw.

In the past, I have flattened the edges on my planer-bed, using a medium grade paper taped to the bed.
However, I prefer going all round in one sweep with a sharp hand-plane of suitable size, to 'joint' the edges.

HTH

 

[recipio]

Found this while browsing lid cutting options. Its easy enough to separate the lid but to do so with precision and not leave any 'dips' or saw marks is hard. On a table saw I've found the best way is to cut the two long sides of the box then stick some 6mm ply on over the cuts with double sided tape and proceed to make the short cuts.The box will not wobble unlike using slips of wood in the cuts. I suspect a slitting cutter on a router table would give even better results ?

 

[profchris]

Japanese pull saw. I just scribe a line with a marking gauge and then cut along it. Minimal tidying up required, just don't rush the cut. A vice holds the opposite side to the cut, so tends to spring it apart rather than pinching it closed.

 

[Chris152]

I'm making a test box at the moment and plan to cut the top off using a router bit (the router's in a table) and leaving a little to hold the structure, as suggested above.
Is it easier/ safer with a 3mm bit than 2mm? Do they tend to snap being so thin? (I'm assuming you take it steady with about 3mm cuts on each pass. The wood is beech.)

 

[custard]

You'll be fine with a 2mm or a 3mm cutter, obviously 3mm gives you a bit more tolerance for sawing so that's what I'd recommend for your first go at this technique. The price you pay is that flushing down the sawn edge is a slightly longer job.

Personally, I prefer to get a coat or two of finish on the entire box before sawing off the lid. But whenever you choose saw slowly, constantly adjusting the cut to remain central, and tape in small wedges to hold the kerf open and rigid.

The mating faces of the two sawn surfaces needs to be made absolutely flawless. Many people will judge the quality of the box by the quality of this shut line, so aim for perfection.

I often use one or a combination of two techniques.

First, if the grain is fair and the timber sweet working I'll hand plane the two mating surfaces flush. Your hand planing skills need to be pretty good to reliably pull this off. I find it easier with a slightly cambered iron,

Second, if planing will be problematic, then coat a 25mm thick board of MDF with some wide abrasive paper from an industrial sander. I think from memory mine has 120 grit on one side and 180 grit on the other side, by carefully moving the working around you'll guarantee two dead flat surfaces. It's worth putting some effort into making one these sanding boards as they last for years and are invaluable in all sorts of applications where you need absolutely precision components,

The end result should be a box lid that closes without any trace of binding and with a totally even shut line, fine quality work to this standard is fully within the scope of the home woodworker provide care is taken throughout,

 

[doctor Bob]

I'm curious as to why a 3mm cut on the table saw is too much?

 

[Jacob]

Table saw. It's a big box so there is some chance the thing will spring out of square once separated - so be prepared for a little more work!
Yes insert kerf width slips into the cut to prevent the gap from closing up and moving in to the blade.
Sanding the edge - 2 or 3 sheets of sand paper lightly attached to a flat board. Doesn't matter if there are gaps as you will be moving it about a lot.