Thread: Mortising Jig

Hi Rocker, That looks very impressive to me.

Can I or we assume you will give free lessons, or an idiots type sheet

John,

I am afraid there is no substitute for RTFM (Read the F****** manual)
Anyway, I think I have only managed to scramble about a third of the way up the learning curve, so it would be a case of the blind leading the blind.

Rocker

Hello All,

It only took me about a year after I actually requested the plans from Rocker, to actually pull my finger out and build it, but I'm really happy I finally did.

Last year I built a baby change table for some close friends. For this I used dowels. To say the least it was slow and tedious, with me having to mark each individual join etc. Some other friends were due their first child this year and again the call was made for another change table. After the grief of using doweled joints last time, I thought that mortices should be attempted this time.

All the hardware came from Bunnings. Knobs, threaded rod, t-nuts came to about $30. For the timber, I bought three 1.5m Jarrah pickets for a total of about $5.50. All I did was laminate pieces to achieve the desired thickness / width with little waste and next to no cost. Obviously a little more time in creating the various resultant dimensions, but hey, I'm a cheapskate and would rather save a few dollars and a tree or two. The MDF I got from Mr Ply & Wood, as they can supply smaller off cuts, instead of me having to buy a great big sheet for only a small amount needed. About another $5.50 there.

Since it was so long between me receiving Rocker's plan and actually building it, I was able to take advantage of his advice in a subsequent revision of the design. This included the reinforcing for the platform, the spline for the join and the use of the kitchen chopping board for the fence guides. (wasn't able to find any brass bar anyhow...) I skipped the dial gauge, and instead will rely on a vernier or accurate ruler.

For the table I had to make thirty mortice cuts. Once I had the jig set, and a couple of test cuts made, I think I was able to get through all 30 cuts in a bit over an hour. Once the workpiece mortice centreline was aligned with the jig, the cut was easy and straight forward, with little chance of error. Since every mortice cut was identical, there was no issue with trying to match a tenon with a partner mortice. The assembly was an absolute piece of cake, with every join being both smooth and snug.

The jig and outcome change table are attached.

Rocker. Thanks very much for your contribution to us all with your jig. It's made life much easier for me.

Paul.

Hi,

I just got myself a router and want to use it to make mortice & tenon joints.

This jig seems to be very popular.

I sort of get how it works but would someone mind explaining how it is used ?

I don't see how you control the width of the mortice.
eg: making a 3/8th mortice with a 1/4 bit, etc.

Which is considered easier, rounding the tenons or squaring the mortice.

Can this jig be used to route mortices in the end grain of boards ?

Thanks

I don't see how you control the width of the mortice.
eg: making a 3/8th mortice with a 1/4 bit, etc.

To make a 3/8" mortice, you use a 3/8" bit. The jig only has one fence, so you can't make a mortice wider than the bit you are using.

Which is considered easier, rounding the tenons or squaring the mortice.

There is a lot of debate over this. Rounding the tenon is probably quicker. If it's a through mortice, it depends on the look you want.

Can this jig be used to route mortices in the end grain of boards ?

Yes.

Rocker gives details on how to use the jig in his plans (I think).

Gazza:

The last M/T job I did 192 joints ( 12 planters) which were made using a pine softwood I found that I did not have to round over the tenons I just whacked them in with glue. No test fitting apart from the first cut joint to ensure my jig had cut correctly.

Most probably would round over tenons though in an hardwood or firmer type softwood.

John, you are a brutal man.

Whacking them poor defenceless joints.

Originally Posted by Rocker

Adam,

If you don't have a table saw to cut the spline, you could just rout a 3 mm deep, 6 mm wide, groove in the underside of the horizontal platform, and rout a rabbet on the top edge of the vertical support, so that there is a 6 mm thick 3mm long tongue left to fit into the groove.

Rocker

Rocker, A long time ago I know, do you find that a simple glue and screw butt joint is not strong enough? What about reinforing with corners brackets (on the short side) instead of the spline?

Gazza,

Ideally, as SilentC says, you should use a 3/8" bit to rout a 3/8" mortice; but if you don't happen to have a 3/8" bit, you could rout a 1/4" mortice, then move the fence 1/8", and widen it to 3/8". Not that hard; but you would need to ensure that your feed direction was right on the second pass.

Yes; the jig can be used, very effectively, to rout mortices in end grain.

Adam,

The point of the spline, or tongue and groove joint, is to ensure that the vertical support of the jig, to which the workpiece is clamped, is exactly parallel to the fence. With a simple butt joint, it would be hard to ensure that the vertical support was properly aligned.

Rocker

Originally Posted by jow 104

I just whacked them in with glue.

Wow, you must have strong glue, or sloppy M&T's


I reckon it's best to use a whatever size mortice you want sized bit, rather than stuffing around moving the fence.


I suggest you don't drop the jigs from height.

Originally Posted by paulver

All the hardware came from Bunnings. Knobs, threaded rod, t-nuts came to about $30. For the timber, I bought three 1.5m Jarrah pickets for a total of about $5.50.
The jig and outcome change table are attached.



Paul.

Paul, both the jig and the table look great, but which section in Bunnings did you get the tri-knobs?

John

Originally Posted by Rocker

Gazza,

Adam,

The point of the spline, or tongue and groove joint, is to ensure that the vertical support of the jig, to which the workpiece is clamped, is exactly parallel to the fence. With a simple butt joint, it would be hard to ensure that the vertical support was properly aligned.

Rocker

Ahhh, I see.

When you first see these jigs, your first impression is always that is is so absurdly simple. But it's not until you start building it that you find these things out and have to go through 10 iterations before getting it right. In this case, you've done those iterations for us (thanks) as has derek with his beltsandergridersharpenerhoner.

I built Rocker's Mortising Jig to make his rocker.



It now occurs to me that I was operating from the wrong side of the jig. I believe that the direction of the revolving router bit is such that it is best to cut the mortise from right to left with the fence between the operator and the router. The revolution of the router bit would then force the router against the fence.

I moved the router from left to right with the fence on the other side of the router, as is shown in Paul's post above. Unfortunately, on a couple of mortises, the revolution of the router bit pulled the router away from the fence making a sloppy mortise. (I repaired these by filling the mortise with a timber plug and re-routing.)

So, my question is: "Is my conclusion that you use Rocker's jig with the fence between the router and the operator correct?":confused:

Don,

You are absolutely right. I am afraid my description of the operation of the jig does not spell it out, since I assumed that anyone sufficiently router-savvy to use the jig would know the correct feed direction when using a fence to guide the router. I have now modified the jig article to specify which side of the jig to stand.

There is a picture of the jig in use here in post #54: http://www.woodworkforums.ubeaut.com...?t=9500&page=4

Rocker