Author Topic: 3-way joint for box frame.  (Read 20073 times)

Offline raynerd

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3-way joint for box frame.
« on: October 15, 2011, 03:10:19 AM »
Hi guys

For my clock case, I want to make a "frame" from wood and my design will be, at a very simplified level, a box frame. If you can imagine, at each corner there will be 3 piece of wood mating at one joint.

I`ve been doing some practice at lap joints and a comb/box joints but neither of these will be good for a 3 ways joint. I`ve been told to use a lap joint and then a mortice and tenon joint for the third joint. Is this the easiest way?

Chris
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Offline Jasonb

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Re: 3-way joint for box frame.
« Reply #1 on: October 15, 2011, 04:03:38 AM »
Its teh easiest but you will see end grain on the two lapped timbers.

The ideal is a 3 way secret mitre but very complicated and not really practical on a small display case.

I would first run a groove to take the glass in all the timbers, mitre the top ones and then form an "L" shaped tennon on the end of teh vertical corner ones to fit up into the groove. If you are not sure I'll do a sketch. This big case that I have just done for a modelboat is similar in construction but used studs & nuts instead of tennons as it needed to be flat packed for transport.

Another way is to use "L" profile corner posts that are set back a little from the mitred top and simply slip into the glass groove, used that method for one of my  this model although the top is solid the method will work with a glazed top

J

Offline spuddevans

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Re: 3-way joint for box frame.
« Reply #2 on: October 15, 2011, 04:17:25 AM »
I think we need to have a little more info, or perhaps a rough sketch of what you are wanting to construct. If I understand correctly, you are wanting to build an open fronted box, ie, two sides, a top and a bottom and a back, and perhaps have the front glazed?

What sort of wood are you using?

I`ve been told to use a lap joint and then a mortice and tenon joint for the third joint. Is this the easiest way?

I wouldnt have said that a mortice and tenon joint is the easiest way, it could look very nice, but perhaps not as nice as joining the sides to the top/bottom with dovetails, but that is more difficult than the mortice and tennon joint.


There are a number of ways of doing this, the easiest way is to just butt the sides to the top and bottom and glue&screw them together and then pin the back on to hold the whole thing square.

A slightly harder way, but better would be to attach the sides to the top and bottom as above, then using a router, make a rebate around the inner edge of the rear of the top/sides/bottom assembly, just slightly deeper than the thickness of your backing material, then cut the backing piece to be slightly smaller than the rebated opening (to allow for movement of the wood in the sides/top/bottom) and pin in place.

One of the finest looking would be to dovetail the sides to the top and bottom, and then rebate the rear to accept the back piece, but dovetailing is not the easiest method to do.

I would say not to glue the back into the sides/top/bottom assembly if you are using real wood (ie not MDF or chipboard/plywood) as when it moves with moisture changes the back will not allow the movement and will cause distortions and even splitting. It is better to just pin the back in place with a few small brads (tiny nails).

That's just my rambling thoughts, a lot may depend on how comfortable you are with working with the brown stuff and what equipment you can get your hands on to help you.


Tim
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Offline Swarfing

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Re: 3-way joint for box frame.
« Reply #3 on: October 15, 2011, 04:26:57 AM »
Chris the easiest method i know is to use two dowels? just 4 holes to drill, insert dowels with glue and clamp. All you need to worry about is your holes are centre and your ends are square.
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Offline Jasonb

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Re: 3-way joint for box frame.
« Reply #4 on: October 15, 2011, 04:37:30 AM »
Spud, it will be glazed on 5 sides and teh "box" is justy a timber frame to cover the edges of the glass, no point in doing all that work on a clock and only being able to see it from the front. Though a mirror for teh back panel is sometimes used.

J

Offline raynerd

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Re: 3-way joint for box frame.
« Reply #5 on: October 15, 2011, 04:41:07 AM »
I appreciate your fast responses!

Tim, here is a quick sketch of what I`m making, although I was hoping to keep all clock related stuff in my clock thread, but I`ll just link out to this one. The sketch shows the back as glass where of the course the back will be wood and just front and sides glass. The front will also have a door planted on it so most of these joints will not be seen from the front as the door will cover them.



Swarfing, the dowels method I have considered and seems the easiest but a little too easy and perhaps not strong enough. The wooden batterns are all 1 1/2" square so quite chunky.

I did consider doing either 1 simple lap joint and then a dowel to each of the two piece.

Jason, the secret mitre is well above me at the moment. Could you please tell me more about "a groove to take the glass"? My intial idea was to cut a rebate around the edge but at 1 1/2" thick, it`ll be quite a deep groove to get the glass close to the front edge. I hope you don`t think I`m being thick, but not knowing anything about woodwork, I don`t really know what you mean about:
Quote
mitre the top ones and then form an "L" shaped tennon on the end of teh vertical corner ones to fit up into the groove
use "L" profile corner posts that are set back a little from the mitred top


any more info would be appreciated!

Tim - just a couple more things. I really don`t fancy doing a dove tail, I`m not skilled enough and it`ll look rubish. I have a good set of chisels and a few good quality, sharp planes as well as a shoulder plane but that is it. At a push, I have access to a circular bench saw.

Regarding wood, It was sold to me as a piece of old maple but when I had it planed up and cut to size, my mate told me it was nothing like any maple he has ever seen..almost orange in colour. Infact, I`m not that impressed with it but hey ho...I can`t afford any more and this will be a good practice so I`ll use what I`ve got!



Now however, it has been split down the middle and cut into 1 1/2" square lengths.
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Offline raynerd

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Re: 3-way joint for box frame.
« Reply #6 on: October 15, 2011, 04:45:35 AM »
Ohh, just another point. That quick sketch in sketchup shows the battons with no thickness! I wanted 1 1/2" wood because I wanted the "chunky" wood look but I think maybe there is too much wood on the inside not necessary. Could I possibly take say 1/2" off the corner or even take the inside corner off the wood?
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Offline spuddevans

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Re: 3-way joint for box frame.
« Reply #7 on: October 15, 2011, 04:53:26 AM »
Spud, it will be glazed on 5 sides and teh "box" is justy a timber frame to cover the edges of the glass, no point in doing all that work on a clock and only being able to see it from the front. Though a mirror for teh back panel is sometimes used.

J

Ahh, of course  :doh: :doh:

I assume (very dangerous but I gotta keep trying) that the front will be hinged to allow for adjustments to made?

I would be inclined to mitre the joints between the sides and top/bottom and just butt-join the joints between back and sides/top/bottom, and the same between the front frame(that the hinges are mounted on) and the sides/top/bottom.

A mortice and tennon joint is overkill in my view, the strength will come from the silicone holding the glass to the frames and not the type of joint used to holding the wooden frame together.


If you were feeling adventurous you could take a leaf out of the aquarium builders book and just use high-strength silicone to hold the glass together (assuming that the glass is strong enough to take the strain) and not have a frame at all, using Jason's idea of using a mirror as the back would look really good.


Tim

edit.

I just saw your sketch, you could still make it frameless in the top part with a wooden base.
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Offline Jasonb

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Re: 3-way joint for box frame.
« Reply #8 on: October 15, 2011, 05:00:53 AM »
Can you give an idea of overall size, looks about 4ft tall and it sort something out.

J

Offline raynerd

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Re: 3-way joint for box frame.
« Reply #9 on: October 15, 2011, 05:30:35 AM »
Sure, it`s actually quite a bit higher at 5 foot. The higher it is, the longer the weight can drop so the longer the run, which is why I`ve decided on a floor stander in the first place.

Approximate outside dimensions 5' x 11" wide and 5" deep although just need to make sure that looks in proportion. The 11" width is fixed as I`ll need this to hold the face central and allow the pendulum to swing.

EDIT:  Tim, yes, I was well into aquascaping and use to own an ADA tank..cost me a fortune but all held by silicone and no bracing. I don`t know...think it might look odd over a clock?

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Offline mike os

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Re: 3-way joint for box frame.
« Reply #10 on: October 15, 2011, 11:51:13 AM »
not overly difficult ( but then I am a bench joiner & cabinet maker) :D

uprights should go floor to top in one piece
rails (horizontal bits) should be blind tenoned into the uprights
face panels go into groves in the frame as you assemble (no glue on panels or they will split), if they are to be flush with the face of the frame then the edge of the panel is rebated to bring the face flush

top the same way if flush or held on with buttons from inside if overhanging

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Offline spuddevans

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Re: 3-way joint for box frame.
« Reply #11 on: October 15, 2011, 12:00:28 PM »
EDIT:  Tim, yes, I was well into aquascaping and use to own an ADA tank..cost me a fortune but all held by silicone and no bracing. I don`t know...think it might look odd over a clock?

I guess it depends on what look you are going for, if you want a traditional style then the frameless option may not suit.

Either way, having a mirror as (or on) the back will add greatly to both a traditional style and a modern frameless version.


Tim
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Offline raynerd

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Re: 3-way joint for box frame.
« Reply #12 on: October 15, 2011, 12:38:07 PM »
Mike

What do you mean by "face panels go into groves in the frame as you assemble (no glue on panels or they will split)". My plan for the glass panels was to just  take say 1/8" width and 1 1/4" depth off the inside edge of each piece (I presume this is what is meant by a rebate) and then push the glass up inside the rebate and hold it there with a few very small panel pins.

How long would the blind tenons be if my timber is 1 1/2" square? Won`t they hit each other in the middle?

My current most confident joint was a simple lap joint on two of the parts and then dowel the other piece putting in two dowels, one in each of the woods that are lap jointed...hopefully holding everything together.



Tim - If I did put a mirror on the back piece. Would you just some how drill through the mirror to mount the backplate of the clock? I struggle seeing how to best mount the clock backplate to support the weight of the clock. My intention was to have quite a heavy thick backboard to allow a good fixing point. 
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Offline mike os

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Re: 3-way joint for box frame.
« Reply #13 on: October 15, 2011, 12:54:36 PM »
I'll do you some sketches... if i forget...remind me, brain is calcifying :doh:
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Offline Jasonb

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Re: 3-way joint for box frame.
« Reply #14 on: October 15, 2011, 01:01:06 PM »
The grooves that we have both suggested  would be like cutting a keyway down the length of the timber, you could probably use 3mm glass so say a 3mm wide x 5mm deep groove. This method does trap the glass during construction so parts need to be finished on the inner edges first but it looks a lot neater than rebate and pins on the inside.

The tennons can be stopped before they touch or roughly mitred where they meet out of sight.


Th etwo disadvantages of lap joints is that you see endgrain and they are not that strong.

If the back need  to support the clock then use a ply or MDF back with a drilled mirror in front.

Do you want teh door to fit infront of teh structure you sketched - would look quite bulky, or to have the door as part of what you have drawn, eg part of teh front pair of legs become the door frame.

Offline dsquire

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Re: 3-way joint for box frame.
« Reply #15 on: October 15, 2011, 01:07:05 PM »
Mike


How long would the blind tenons be if my timber is 1 1/2" square? Won`t they hit each other in the middle?

You can either mitre the blind tenons or offset them.

Cheers  :beer:

Don

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Offline Jasonb

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Re: 3-way joint for box frame.
« Reply #16 on: October 15, 2011, 02:05:40 PM »
Here's a sketch of what it could be done like, the height is not to scale only had room for about 1000mm on teh A4 paper.

The tennons could be mad elonger and go into mortices but I've shown them at about 10mm long to match a 10mm deep glass groove. The back just has a wider groove to take mirror plus MDF/PLY.

to stop it looking over chunky I've split the front down the middle to give a door frame approx 1 1/2" x 7/8" and teh same for the front frame.


Offline raynerd

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Re: 3-way joint for box frame.
« Reply #17 on: October 15, 2011, 06:58:39 PM »
I just wanted to say a big thanks Jason for the time taken in doing the drawing for me. It has helped lots and has also changed my plans to make the case more in line with what you have drawn.

I have just been down stairs to have a practice at the joint on some scrap offcuts only to wake up by my wife and daughter so sadly, despite doing all my metal working in the late evenings, woodworking appears noisier and has been banned after bed time! The is going to cause this case build to drag on for even longer! I`m away with work from Monday until late next week so it`ll be late next week before I even have my practice now!

On a different note, I did manage to take some photos of my wood to see if anyone can identify it. like I said, I`m not very keen on it. It was sold as Maple but it doesn`t look like it to me or the carpenter that cut the plank up for me.





Here is a piece of redwood/pine just for colour comparison


The story goes that my wood came from a yard in wigan which closed down but was an importer of exotic hardwoods. Any idea what it is?

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Offline DMIOM

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Re: 3-way joint for box frame.
« Reply #18 on: October 15, 2011, 07:29:06 PM »
.......this case build to drag on for even longer! ....

just an observation Chris - I don't know how long it is since the board was ripped into those rails, and where it's been kept since - but it may be no bad thing for some time to elapse to let it settle. Ideally, it should be left to acclimatise in a location with similar temperature and humidity to its eventual home - so whilst you're away, you could leave it with a clear conscience!

Dave

Offline HS93

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Re: 3-way joint for box frame.
« Reply #19 on: October 15, 2011, 07:56:19 PM »

it is not maple, I would stack it nice and flat with sticks between and not touch it for at least a month and see what shape it takes and what opens up, although I am a time served joiner i have been out of the trade for a long time timber spices seem to change over the years , what we wouldn't make pallets out of is now used for fine furniture, but one thing is for shore that is not what I call maple.
as you are going to put a lot of effort in to the case I would look for some old table tops from schools labs /tables/shelves  etc I got some at one time and it made a very nice table.

Peter
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Offline HS93

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Re: 3-way joint for box frame.
« Reply #20 on: October 15, 2011, 07:58:48 PM »

Have you thought of going high tech and make it out of ally extrusion ?

Peter
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Offline Bluechip

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Re: 3-way joint for box frame.
« Reply #21 on: October 16, 2011, 03:29:13 AM »
The wood could be an Australian timber called Queensland Maple ... which is not actually a Maple.

It does resemble the grain and colour, but cameras & screens are not accurate.

Or it could be a lot of other spp ...  :lol:

Helpful  eh...  :thumbup:

BC

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Offline HS93

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Re: 3-way joint for box frame.
« Reply #22 on: October 16, 2011, 03:55:57 AM »
The wood could be an Australian timber called Queensland Maple ... which is not actually a Maple.

It does resemble the grain and colour, but cameras & screens are not accurate.

Or it could be a lot of other spp ...  :lol:

Helpful  eh...  :thumbup:

BC



I was at the home and renovation show the other year and there was an Ausey firm who where bringing in timber from Australian at competitive prices
Peter
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Offline spuddevans

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Re: 3-way joint for box frame.
« Reply #23 on: October 16, 2011, 04:21:12 AM »
Tim - If I did put a mirror on the back piece. Would you just some how drill through the mirror to mount the backplate of the clock? I struggle seeing how to best mount the clock backplate to support the weight of the clock. My intention was to have quite a heavy thick backboard to allow a good fixing point. 

You wouldn't drill it, it is much easier to get the glazier whom you get the mirror off to drill it, they have all the right bits and the experience to drill it without cracking it. You'd just need to bring the relevant dimensions for where the holes need to be. I'd get them drilled big enough to allow you to attach the clock mech' directly through to the back so that you are not tightening the clock onto the mirror.


As to the identity of that wood, it looks like a cross between light oak and beech, lets just say it's Boak :D :D

I really dont think it's maple, doesnt maple have a closed grain structure, ie no pores? :scratch:


Tim
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Offline Jasonb

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Re: 3-way joint for box frame.
« Reply #24 on: October 16, 2011, 08:26:18 AM »
Its defo not Maple or oak / beech for that matter. Possibly Iroko, does it have an oily feel? But there are a lot of African woods and ones from tropical areas that have a similar looking grain structure.

J

Offline mike os

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Re: 3-way joint for box frame.
« Reply #25 on: October 16, 2011, 08:45:43 AM »
does the dust smell peppery?

looks like iroko.. but could be one of several... wear dust mask for sanding/machining
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Offline Zephyrin

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Re: 3-way joint for box frame.
« Reply #26 on: November 16, 2011, 02:13:38 PM »
HI
the wood you have is most probably "Ramin" from the tree Gonystylus bancanus from malaysia.
It has characteristics and uses similar to those of beech, but yellowish.  Little breaking and light enough (density 0.7), it has a good resistance to bending. it is very easy to cut tennons and mortices in it, but hard to polish and wax in my own experience, may I add IMHO that a clock frame deserves better.
cheers

Offline raynerd

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Re: 3-way joint for box frame.
« Reply #27 on: November 16, 2011, 02:32:32 PM »
Yes, thanks for the input. I decided not to waste any time on it and have got rid of the wood. I now have Oak on order.

Chris
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Offline ncollar

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Re: 3-way joint for box frame.
« Reply #28 on: January 02, 2012, 08:30:42 PM »
OAK, that is just as bad, mahogany or cherry. the contrast with all that brass would look good
Nelson Collar

PS Oak will work, use a stain to darken it some. :coffee:

Offline raynerd

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Re: 3-way joint for box frame.
« Reply #29 on: January 03, 2012, 05:27:36 PM »
The clock is now complete and in my opinion, the case looks superb and I couldn`t have dreamed on anything better!! light oak.  :poke:

http://madmodder.net/index.php?topic=5466.0

Chris
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