I make small boxes with mitred corners. Usually I spline the mitres, but have just bought a lock mitre router bit set from Linbide, a New Zealand maker.
There are heaps of instructions on the web – here and on other fora – about the more conventional lock mitre bits.
Does anyone have any experience with the type of bit detailed below? Jig hints? Set-up hints?
I’ll learn the hard way, but wonder if anyone can provide some help first?
Linbide’s information follows:
| For some time the Mitre Lock Joint has been a problem to accurately produce consistently. The difficulty is making a square joint, because one panel has to be machined flat and the other panel must be cut in the possibly unstable vertical position. THIS PROBLEM IS NOW SOLVED! Both panels are now able to be machined on the flat – where maintenance of accuracy is assured. Note: it is recommended that a router table be used to assist in the accuracy of the cuts. ALL CUTS ARE PRODUCED WITH THE PANELS ON A HORIZONTAL POSITION. Instructions are supplied. | View Image |
| ||
| • STEP 1. First 45º tongue is produced in Panel ‘A’ using Bit No. 1. • STEP 2. Second 45º tongue is produced in Panel ‘B’ using bit No. 1 also. • STEP 3. The Trench is produced in Panel ‘B’ with Bit No. 2. A strip of waste is produced. • STEP 4. Line up panel ‘A’ tongue with trench in Panel ‘B’ then join | ||||
Replies
Seems to me that the difficulty would be getting the second bit aligned properly (correct height).
How is this faster or superior to simply using a 45 degree bit on both corners and then using a second bit (or the TS) to create a slot for a spline? I'd think that method would require no alignment and would be faster. Am I missing something?
John
Kiwi,
I have run a lot of lock edge miters, but with Freeborn cutters on a shaper. They look virtually identical to the setup you have.
After running both sides of all of them, I just run half the total through the table saw with a 1/4" dado blade, to cut the tongues off and form the dado for the tongue.
The fits should be very, very tight. So tight that you can't use much glue at all, and only on the surface closest to the outside corner.
Even if you are able to get the joint together with a lot of glue, it will swell the wood toward the inside of the joint and open up the outside of the joint. The visible part naturally.
I use spar varnish to glue mine together now.
Clampman
Thanks Guys
I spent a bit of time today making a sledge style (sliding table) hold-down for my router table, with a clamp to hold the box sides in place and a flip-out end stop to accurately locate them, and ran a few trial cuts.
The reason for trying a lock mitre is because it's faster than cutting a plain mitre and then splining. Maybe. I usually use stopped splines that don't show when I cut open the boxes, and that's fiddly and takes a bit more time, especially in 10-12mm stock. (The top and bottom panels are glued into rebates, and so the splines don't show there either.)
I use a mitre saw and then take a few slices off with a shooting board to produce nice sharp mitres that join with no glue line. Usually I only need one or two trial clamp-ups, often only one. I've got it down to a fine art.
I figured nice clean locked joints would look OK when the box tops are sawn off, and that might be easier and faster than machining stopped splines with a router in a 45 degree jig.
But I'm not so sure. There's lots that can go wrong, even with a good solid well-designed hold-down. These are small joints, and need to be perfect and quick to do.
I'll play around some more, and see whether I think lock mitres is a better approach. I'm not betting on it tho!
If you're doing a production run with a number of boxes using the same thickness of material, the LM joint should work very efficiently once you get it set up accurately. The big problem with LM joints, IMO, is when a person needs to make just one or two of something -- the set-up time is way out of proportion with the work being done.
Let us know how this goes -- I'm seriously considering a LM bit for a multiple-piece project.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Forestgirl,
I see you're thinking about going the lock miter route. Here's a tip for you that will make life easier. MLCS has 2 sizes of lock miter bits, both 1/4" and 1/2" shafts, for material up to 7/8" thick and for material over 1" thick. They also sell a set-up block with the profile cut into it. The set-up block I bought is milled to 3/4" inch thick, so setting up for even a small run is simple. Hope this information helps.
Don Z.If I was doing any better, I couldn't hardly stand it!
It's Sunday in New Zealand and I've spent an hour or two tinkering and thinking about this.
It's a strategic issue for me, as it is for the girl from the forest ... I'm about to embark on a longish series of boxes, all with the same construction approach, but all different (material - brown oak, English walnut, kauri, rimu; sizes; lid treatment ...) and all machined, one by one, from seperate small pieces of stock. These are high value, one-of-a-kind, elite, products, and it's difficult to fit them easily into a single, same-dimension, production run.
I've rebuilt my mitre shooting board, and made a new 22" wooden plane, and I reckon I can hand-plane perfect mitres in less time than it takes to run them through the router. I'm working with 10-12mm stock. My board setup and new long plane with a Clifton iron produces whisper thin cross-grain shavings and I can shoot a mitre, from a square start, on a 12mm board in about 2 minutes. And, here's a key point, I enjoy doing it.
Also, unless you're doing a long run, and can standardise the whole process, the lock mitre is a risky (meaning subject to high variability and likely to go wrong) maching operation. I instinctively don't like cuts that rely on hold-down and hand pressure.
So. The view today: lock mitres using a router table and a hold-down (even a pretty sharp hold-down) are not the best way to join small boxes in short runs. Expensive experiment, lesson learned.
What is? I'm thinking about returning to a method I abandoned about 20 years ago, and that's plain mitreing, using the top and bottom panels to add strength at the ends of the mitres, and then using a 45 degree jig to cut in a slot for a key or keys, after glue-up.
I want to get away from stopped splines.
I've got a few boxes kicking around the house and around my workshop that I made more than 20 years ago, on the other side of the world, in sometimes difficult timbers (elm, ash, plain-sawn oak, mahogany) which are plain mitred with no interlocking joins - just clamped together like picture frames, with the glue doing all the work. They have survived. I've never had a box returned because of seperation at the corners.
What this tells me is that the quality of the mitre - how well the two faces meet - is at least as important as the joinery method. Maybe plain mitres and a couple of quick to cut keys is enough?
Have you considered thru splines, making them a decorative element by using a contrasting wood? If you're considering a very visible keyed miter, a thru miter shouldn't be above consideration. They would be much easier than stopped miters, less obvious than keys, but quietly elegant there in the corners of your boxes.
--
Lee in Cave Junction, Oregon
On the Redwood Highway
No, I haven't thought of that. I guess if a machined lock mitre is an option, then why not a well made through spline?
It's just me. I don't like the joinery to show on these very sophisticated pieces of woodwork (so why consider keys? They look decorative, not functional, I'll probably only use one at each corner, just below the opening, and if I use a real skinny router bit they'll look more like an accent for effect and not a `join').
Incidentally, I see the latest FWW has a lead article on this subject. I've ordered a copy, but it won't be here for weeks. I'll be miles down the track by then!
Another subject that is exercising me at the moment is lids. Traditionally I've used bookmatched veneer on 3mm ply or customwood as the lid panels, glued into a rebate and with a contrasting strip of something like rosewood between the panel and the rebate. Makes a strong, light, stable lid. However, I just made a ceremonial box with a lid panel made up of pieces of heritage timber, with a couple of carved panels and some inlay (I'm really keen on paua as an inlay - a very bright, splashy South Pacific version of abalone or mother of pearl), with rosewood cocked beading between each piece - sort of like a patchwork quilt effect. I love it, and will do more. But there are movement and finishing problems (part-solved by rebating the pieces of the ceremonial box lid and using the cocked bead to hold them in place - a multi-fielded-panel).
I'm thinking parquetry, using my own 2-3mm thick sawn and thicknessed veneers, with cocked beading either routed in or mitred in between the pieces. Stained glass windows and patchwork quilts are the inspiration. I'm moving away from production runs of similar boxes, to one of a kind works of art. Small numbers, high value. I'm excited by the look of the sample lids I've been playing with, and the ceremonial box attracts lots of wow responses.
Kiwimac,
You are aware there is a video clip on here for cutting keys? Uses the TS and a jig...just in case you were not aware.
Hi Don, and thanks. I'll check it out!forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
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