Combed Joint

[OakSniffer]

Hi,
could anyone help with the best approach and tooling required to create an accurate "Combed Joint".

Thanks

 

[ByronBlack]

Oaksniffer, what is a combed joint? Is that the same as a finger or box joint?

Because if i'm correct and thats what you are after, you can achieve a good accurate joint using a router. Here's a PDF from this site with instructions:
https://www.ukworkshop.co.uk/pdf/UKW_boxjoint.pdf

 

[George_N]

For the router table a finger jointbit might fit the bill. Mainly used for end grain to end grain joints as seen in IK*A furniture.

 

[OakSniffer]

Hi Guys,
thanks for your replies.
I should of been more specific here, the joint is for top/bottom rails and stiles on casement window and frames.
The joint is two fingered and the profiles are 55x68 for for the casement and 90x58 for the frames. Hope this all makes sense!

On another note can anyone recommend a place to store photos so i can post them on the forum.


Cheers

 

[Newbie_Neil]

Hi

On another note can anyone recommend a place to store photos so i can post them on the forum.

Try here.

Cheers
Neil

 

[OakSniffer]

 

[OakSniffer]

Thanks Neil your a star!

 

[Steve Maskery]

Hi Oaksniffer

A joint like that is not easy for us home woodies to create. In industry it will be done with a spindle moulder. Scrit is the best one to advise you on that.

At home, your best bet would be to use a bandsaw, or a horizontal router jig, or forget about the joint (I'd have called it a double bridle joint, comb joint is usually used to refer to those like previously described) altogether and use loose tenons. You can easily get two in such a section. If you only have a few to do, use your router, if you have lots, get a Domino.

One thing concerns me about the drawing. If you are making a replacement, the glass unit needs to be 4-16-4 for building regs. With a 15mm bead and a mm of compound, you are left with only 4mm of wood behind the glass. That doesn't seem very much to me. Even if the glazing beads are left proud by a couple of mm, you still don't have enough for a moulding, for example.

HTH
Steve

 

[OakSniffer]

Hi Steve,
Thanks for your informed reply; yes I have lots to do!
11 casement windows
2 x sets of external French doors
3 x sets of internal French doors
3 x internal doors
3 x external doors

Call me fool!


Several further questions if I may,

What section would you suggest?

15mm bead
1mm compound (or gasket)
24mm glass
1mm compound (or gasket)
15mm beaded edge

56mm in total?

I don’t have a problem purchasing a spindle moulder the budget allows for it. I’m just not sure on the best methodology.

Any tips on speeding up the production of the loose tenons?

You mention the Domino, its certainly an option, my main concern will be the strength of the joints.

Many Thanks

 

[Steve Maskery]

Call me fool!

If you insist!

What section would you suggest?

15mm bead
1mm compound (or gasket)
24mm glass
1mm compound (or gasket)
15mm beaded edge

56mm in total?

Yes, I think that is much better. I'm no expert on architectural joinery, but I were doing it for myself, I would do exactly that. But there are others on here much more knowledgeable about joinery than I am.

Any tips on speeding up the production of the loose tenons?
You mention the Domino, its certainly an option, my main concern will be the strength of the joints.

That's the least of your worries. A double loose tenon which fits accurately will be stronger - much stronger, than the wood itself. I did 23 casements last summer. Quick and easy. In fact, I'm just today cooking up some fake photos (!) as I missed one or two out at the time. I'm writing up the job for GW.

I'm less convinced about loose tenons for French doors. OK if you cut them with a router fitted with a 75mm cutter, I guess, but the max cut on a Domino is 28mm, so, as I've not tried it, I'm less inclined to stick my neck out on that one. But I have some frames, including French Doors, to make myself this year (all being well with the architects and Council) and I'm inclined to try it with dominoes. The beauty is that it is a doddle to double them up, so instead of having one 5/8 tenon, you can have 3 pairs of 10mm Dominoes, cut in a fraction of the time, and I believe they will be very strong, especially given the increased glue area. I just can't be sure that they will be as strong as a through tenon, or resist racking as much. It really needs a proper experiment.

Tell you what, why don't you try it and let me know how you get on?


S

 

[OakSniffer]

Thanks again Steve for your input.

Anybody know who this expert might be?

Cheers

 

[Loz_S]

A small side note, might be useful. Double glazed units in Holland are always made with uneven glass thicknesses. You would never get a 4-16-4 it would always be 4-16-5. (The spacer bars are only made in 2mm steps.)

This apparently stops any interference-patterns becoming visible under some lighting conditions due to the glass thickness being identical. The interference pattern in the glass can create what appears to be a thin rainbow coloured film of oil on the inside of the sealed unit.

 

[Scrit]

A joint like that is not easy for us home woodies to create. In industry it will be done with a spindle moulder. Scrit is the best one to advise you on that.

Not just in industry, by most joinery shops, even the small ones. The joint is either cut on a single end tenoner with stacked tenoning discs or a heavy-duty spindle moulder with stacked tenoning discs. The cutters have large diameter centre borings (typically 40mm or 50mm) and are mounted on a "top hat" section bushing with steel spacer collars in between. Requires a minimum of 4HP and a sliding carraige to use, though, and a pair of tenoning discs, bushings, cutters, etc would probably cost in the region of £300. I have sets of this stuff and could post a few pics here if requested. If the stiles were worked with extra horns a conventional multiple mortise and tenon joint could be worked and the horns sawn off once the glue had set

..... if you have lots, get a Domino.

Call me old fashioned, but I doubt that a Domino will give you the joint rigidity or glue area you actually need. The reason for this type of joint is that, being exposed to the weather, an excess of glueing area is required to ensure that the joint doesn't break-down prematurely. The length of the "fingers" also provides extra mechanical strength which is simply not there in something as short as a Domino "biscuit".

Scrit

 

[ProShop]

I agree with Scrit here, unless you've got a good spindle moulder and the stacked comb set. I've made these before in a production shop and they are the devil to setup.

imho I'd forget combing and just use the time honoured method of mortice & tenon which is much better as you need to get the glueing absolutely spot on or the combing joint will fail rapidly.

 

[OakSniffer]

Thanks Scrit and Steve, usefull advice.

Multiple tenons look like they are the order of the day (short of a lottery win tonight, is it a roll over?)

In your experience what kit and method is the most accurate and affective way to produce them?

Cheers

 

[JFC]

I find that joint very weak and needs to be pegged . It was used alot on storm proof casements . I do all my windows and doors with haunched mortice and tenons and the frames with mortice and tenons , i screw the tenons on the ends and wedge the ones i can .
Tool wise , a bansaw , a morticer and a chop saw with a sliding carriage and a depth stop does me fine .

 

[ProShop]

A spindle moulder, morticer, and table saw do it for me every time.

 

[OakSniffer]

Hi,
JFC what is the purpose of the haunch in the mortice & tenon?
Just curious....

 

[Scrit]

What is the purpose of the haunch in the mortice & tenon?

One of the purposes is supposed to be that it adds stiffness to the joint

As to tools I'm like Felderman, spindle or tenoner for the tenons, square chisel mortiser for the mortises (and remember to leave an extra "horn" at the ends of the piece). A good low-cost alternative to a spindle for smaller tenons is a horizontal router table

Scrit

 

[Modernist]

Hi, I am busy with the same project, tilt ans turn windows, glazed walls with patio door, double doors all with Eurogroove style fittings.

I use a pair of adjustable slotting cutters such as Omas on the moulder with shims to a centre chipper for the wider bridles. I have a Hammer moulder and find the digital height readout worth it's weight in gold for accurate and repeatable fits.

Have a look at my joint drawings under German Tilt and Turn Windows on the projects section from a week or so back