# Squaring Up Mortise And Glueing M & T



## Gaia (Feb 20, 2010)

I'm learning to make interior, exterior house doors, I intend using a router with a straight cutter, aligned on the timber with 2 fences. I would pre drill half inch deep with a brad drill bit, then use the cutter, then drill again and cut, repeating until I reach the required depth. Would I use a mortise chisel or standard bevel one to square up the curved ends of the mortise slot? Someone said to round off the tenons.I'm not sure if rounding the tenons would be easy for me to do properly as have very little experience woodworking. Have read rounded tenons produce a weaker joint I've looked for info on net on how to square up the mortise slot but not been able to find anything.I don't know if cleaning up the slot is straightforward or not, any tips?
Also the size of the tenons with regard thickness of the door stiles, 1/3 or 1/2. How far should the tenon extend into the door stile?
What type of glue to use and glue suitable for external doors, I've read a bit about glue expansion. Should the tenon be a few mms shorter than the depth of the mortise?

Any tips on to fix some type of end stops on the timber when routing the mortise?

All help much appreciated.


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## Cherryville Chuck (Sep 28, 2010)

Gaia said:


> I'm learning to make interior, exterior house doors, I intend using a router with a straight cutter, aligned on the timber with 2 fences. I would pre drill half inch deep with a brad drill bit, then use the cutter, then drill again and cut, repeating until I reach the required depth. Would I use a mortise chisel or standard bevel one to square up the curved ends of the mortise slot? Someone said to round off the tenons.I'm not sure if rounding the tenons would be easy for me to do properly as have very little experience woodworking. Have read rounded tenons produce a weaker joint I've looked for info on net on how to square up the mortise slot but not been able to find anything.I don't know if cleaning up the slot is straightforward or not, any tips?
> Also the size of the tenons with regard thickness of the door stiles, 1/3 or 1/2. How far should the tenon extend into the door stile?
> What type of glue to use and glue suitable for external doors, I've read a bit about glue expansion. Should the tenon be a few mms shorter than the depth of the mortise?
> Any tips on to fix some type of end stops on the timber when routing the mortise?
> ...


Hello again Peter,
Any play around your tenons is only a problem if your glue joint breaks down completely, i.e. the butt joint and the sides of the tenon to the mortice fail. You need a few thousandths of clearance around the tenon for glue; too tight and the joint will be starved for glue and you get a weak joint. Whether the rounded ends of the tenons or the squared ends of the mortice are perfect is not necessarily of critical importance.
You need to make a jig that will guide the straight bit the proper distance from one edge. Make sure you register the jig from the same edge every time. In other words, mark it inside and outside.
Your router will only extend so far, that's how deep your mortices can be. Drill the pilot hole full depth right off. In fact, drill a little smaller than the tenon thickness all along the mortice length if you want, your router will appreciate it.
For tenon thickness I wouldn't go less than 1/3 or more than 1/2, whatever the closest bit size works out to. Tenons should be a little shorter than mortice depth and be fluted so that excess air and glue can escape. 
For glue I would either use Titebond 3 or a urethane glue like Gorilla glue.

In your previous post I also recommended using floating tenons. Have a look at it.


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## Gaia (Feb 20, 2010)

Cherryville Chuck said:


> Hello again Peter,
> Any play around your tenons is only a problem if your glue joint breaks down completely, i.e. the butt joint and the sides of the tenon to the mortice fail. You need a few thousandths of clearance around the tenon for glue; too tight and the joint will be starved for glue and you get a weak joint. Whether the rounded ends of the tenons or the squared ends of the mortice are perfect is not necessarily of critical importance.
> You need to make a jig that will guide the straight bit the proper distance from one edge. Make sure you register the jig from the same edge every time. In other words, mark it inside and outside.
> Your router will only extend so far, that's how deep your mortices can be. Drill the pilot hole full depth right off. In fact, drill a little smaller than the tenon thickness all along the mortice length if you want, your router will appreciate it.
> ...


Thanks again and also for the helpful detailed reply 
" Your router will only extend so far, that's how deep your mortices can be. " 
I understand one can get a collet extension even though I'm using Silverline inexpensive cutters,the two added together might be long enough to cut the mortise? Is it mortise or mortice?. If not long enough I understand more expensive cutters have a longer shank. If the width of the door stile is 10cm how deep should the mortise go?

" You need to make a jig that will guide the straight bit the proper distance from one edge. Make sure you register the jig from the same edge every time. In other words, mark it inside and outside. " 

I don't quite follow you here, could you clarify please? As I mentioned, I have two fences for the router, one on each side of the door stile, is this what you are talking about. Still shopping around for the best price on 1000mm of chrome steel rod so can make the two extended fence rods.

" Drill the pilot hole full depth right off. In fact, drill a little smaller than the tenon thickness all along the mortice length if you want, your router will appreciate it.
I thought the mortise width, " less than 1/3 or more than 1/2, whatever the closest bit size works out to. " So are you saying pre drill the mortise smaller than the width of the mortise then open it up using the same size cutter? Then pre drill again this time using a drill this time the same width as mortise then open it up with the same size cutter? 
Cheers,
Pete.


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## Phil P (Jul 25, 2010)

Gaia said:


> " Your router will only extend so far, that's how deep your mortices can be. "
> I understand one can get a collet extension even though I'm using Silverline inexpensive cutters,the two added together might be long enough to cut the mortise? Is it mortise or mortice?. If not long enough I understand more expensive cutters have a longer shank. If the width of the door stile is 10cm how deep should the mortise go?


Hi Peter

Your Silverline cutters aren't plunge bits, are they? The way to achieve a deep mortise is NOT with a collet extender. They are designed to give you extra depth on a router table where the extender never extends above the surface of the table, but they are obviously of larger diameter than the cutter, so they can't go down the mortise hole! A better approach for deeper mortises is to spring for a good quality deep plunge router cutter, such as the Wealden TXL1416-1/2 which will give you a full 65mm depth of mortise. That is adequate enough for a loose tenon. Need to go deeper? Use an auger bit and a chisel to clean out



Gaia said:


> Make sure you register the jig from the same edge every time. In other words, mark it inside and outside.


When setting out a mortise for hand cutting. you almost always mark the centre line of the mortise first. If using a jig I'd similarly mark the centre line both on the timber AND the jig. The width of cut can be stepped out from the centre line (e.g. a 12mm mortise would require a 12mm cutter and be stepped out 6mm either side of the centre line. A test cut is made in a piece of tomber of identical cross section and the settings adjusted until the cutter is running dead centre between the lines.



Gaia said:


> Still shopping around for the best price on 1000mm of chrome steel rod so can make the two extended fence rods.


Silver steel, dead cheap from any reputable engineers merchants. My local merchant sells the stuff for about £10 to £12 a metre which is cheaper than anything on eBay. No delivery either

Sorry Peter, but all this faffing about with drilling and then using a cutter which can't be plunged is just adding to the potential inaccuracy of your mortises. You have a plunge router so why not use plunge bits? Last set of kitchen bits I bought (2 x 1/2in diam x 50mm high, 1 x 1/2in diam x 65mm high and a laminate trim bit) cost me £16 (Faithful brand, local ironmonger, this retailer has them at £17.40). They work equally well for mortising, as does this set. Think I'd pay the extra for the Faithful ones, though 

Regards

Phil


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## Gaia (Feb 20, 2010)

Phil P said:


> Hi Peter
> 
> Your Silverline cutters aren't plunge bits, are they? The way to achieve a deep mortise is NOT with a collet extender. They are designed to give you extra depth on a router table where the extender never extends above the surface of the table, but they are obviously of larger diameter than the cutter, so they can't go down the mortise hole! A better approach for deeper mortises is to spring for a good quality deep plunge router cutter, such as the Wealden TXL1416-1/2 which will give you a full 65mm depth of mortise. That is adequate enough for a loose tenon. Need to go deeper? Use an auger bit and a chisel to clean out
> 
> ...


I'll get the £17 plunger cutters as you suggest, see my reply in Type Of Mortise Chisel To Square Slot post. Silver steel I only found one in Yellow pages,didn't reply to enquiry just Googled found another in Swindon, just 6 miles up road I go there quite often £4.50 333mm x 10mm, Don't stock metre length, will see if can fine another conpany are they able to cut in half? My angle grinder would probably do, would prefer them to cut.
Ta.


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