Before I start I have to point out that the morticer I made was a rush job I needed it quick and cut many corners. So along with saying how i made it I will say what i would have done if I had taken more time over it and had the materials I would have prefered. I would expect that many people would make a much better looking morticer than I did but thought it was worth throwing the idea out there.
Also having just finished the drawing for the side plates I find I am terrible at drawings so I will attempt to explain them as best as i can.
Now thats out of the way lets begin with the parts:

Parts list
1 off D80/90 flanged motor (mine is .37kw feel free to use larger and more powerful motor if you like but I have found this sufficient for making 16mm square holes in pine)
1 off 50 x 50 box 700mm long ( I would have prefered to use 75 x 50 or similar)
2 off 76 X 38 channel 350mm long
2 off 300 x 200 x 5 plates (this will need to be altered if you use bigger box section and/or different frame motor)
1 off 200 x200 x 5 plate (this will need to be altered if you use a different frame motor)
1 off 50 x 50 x 25 block
1 off 30 x 6 flat 80mm long
1 off 30 x 6 flat 208mm long
1 off 20 x 20 box 600mm long
6 off 6282RS bearings (just in case you cant find the numbers where you are they need to be 8mm id 24 od and width is not that important sealed both sides)
a variety of bolts, nuts, washers, spacers, brackets etc. which i will mention as I go along.
a drill Chuck but this is not needed it can still be used without one. you simply make linkages for each auger.

Step 1: Base

Base
Drill two holes in each of the 76 x 38 channel if you intend to attach the finished morticer to a bench or frame, which i suggest you do to avoid the thing falling over onto you. Its gonna be heavy and you wont want to drop it on your foot.

Make the base with the 50 x 50 box section and the two bits of 76 x38 channel as shown in the picture. I welded mine together but you could bolt it together if you prefer. If you do I suggest at least 3 bolts, there is going to be a lot of force applied here when you are drilling through a knot or some hard wood. The main thing is to check that they are square especailly if you are welding it together.

Clamp it solidly and tack it then check the square while you can still move it. Well I am sure I dont have to tell you welders how to weld.

Step 2: Side Plates Etc.

Access to a plasma cutter or a friend with one would be helpful here.

Motor ring
Start off by cutting a complete ring with holes to match your chosen motor from 5mm thick plate, I have drawn up the ring for the D80 frame motor I used. First pic.

Mortice head plates
Next is the main part of the motor/mortice housing and good luck following the drawing (if anyone could do a better job I wouldnt get upset ;).
If you look at mine in the picture you will see i have drawn it up different, this is because of the chuck which I will explain when I get to that section.
Take your two 300mm X 200mm X 5mm plates and mark your datum line 201mm from the back, make sure this is square to the top of the plates.
Start with the two 8mm holes at the back and make sure they are parellel to the datum. This is the most important measurement on this section, if this is not correct your chisel will not cut correctly into the wood.
Next do the 10mm X 8mm slot, assuming you dont have a miller just drill two 8mm holes and cut through with a jigsaw.
Then the two holes for the chisel clamp the rear most one is 8mm and the front is 8.5 this is to allow a little movement when tightening the chisel in place.
The final hole is tapped m8 and is only required on the handle side of the plate, You could of course tap this hole on both plates so a left handed person could easily use the morticer too.
I hope you are following me so far now we move on to parts of the plate you remove start off by removing the front section this can be done with a power saw/bandsaw or plasma cutter if you are unlucky and dont have access to either then it is going to be a hacksaw job.
You next need to cut out the opening for access to your chosen way of holding the auger in place be it a chuck or sleeves, This is where the plasma cutter or friend with one would help. don't be tempted to cut right through The 11mm bit is left in for rigidity, without it I am sure it would bend out of shape in no time.
There also needs to be a hook to attach a spring mine is positioned on the opposite side to the handle near the bottom of the plate and I am using a spring which came from a child trampoline. I will leave the decision of where and how to attach a spring to you as it will be base upon what you can get hold of.

Tensioners.
The tensioners are made with two 20mm X 3mm strip 90mm long with a 8mm hole drilled 20mm from the end and 2 60mm long bits of m8 threaded bar, weld the threaded bar to the strip so the overall length is 130mm. I just bent some strip and tapped the hole m8 but I think this is a better way.

Step 3: Chisel Clamp and the Rest

Chisel Clamp .
The chisel clamping part of the machine is a block of 50mm X 50mm X 25 solid bar.
Start by marking and drilling a hole in the center of the block to suit your chisels I have this set: http://www.screwfix.com/p/mortice-chisel-set-4pc/15113 they have a 19mm shank but other shank sizes are available and if you have a variety you can make blocks to suit the different sizes and swap them out as needed.
This needs to be accurate I bored mine on a 4 jaw chuck on the lathe. You need a nice fit that will allow the chisel to slide easily into the clamp and not stick until it is tightened in there.
Now turn the block on its side and mark and drill the two hole for holding and clamping. You do not have to tap the rear hole all the way through just tap 20mm into the block each side.
the front is a 8.5mm clearance hole drilled all the way through.
Finally saw a slit through the center as shown (a hacksaw should suffice but if you can make the slit 2mm to 4mm)

Depth clamp .
For the depth clamp I took a strip of 25mm X 6mm X 208mm and drilled a 12.5mm hole then bent it over at the lines shown in the picture (make sure the countersink is inside). Weld the ends together and smooth it for a nice fit over the 50mm X 50mm upright weld a m12 nut over the 12.5mm hole and place a m8 X 25 countersink bolt into the countersunk hole and put a nut on it to hold it in place. It needs a hook or similar welded to the opposite side of the handle bolt, I made this hook by cutting a chain link in half and welding it to the clamp the othe half of the link was used on the mortice head plate to attach the spring there. I will eventually get around to amending this part to make it easier to set the mortice head, its awkward as it is and can slip if not tightened properly.

Linkage.
Nothing amazing here its just a piece of 25mm X 6mm X 70mm with a 8mm hole drilled one end and a tapped m8 hole the other.

Tension brace.
Again nothing amazing 25mm X 6mm X 94mm with two 8mm holes drilled on 78mm centers.

Handle.
Is a length of 20mm X 20mm box section and you need approximatly 600mm in length however I found that this much is a pain in the buttocks (well the ribs in my case ) and cut it down to 300mm then use a larger tube like 30mm X 30mm to slide over it to extend the handle. This way you can remove the extension when it is not in use and you wont impale yourself on it.
You will probably want a few holes on the handle which you can change depending on the amount of travel you require. I used 2 holes because that was all I needed the first hole gives me about 35mm of travel and the second gives me about 65mm. You can increase this but the more travel you have the harder it is to force the chisel into your wood, so be reasonable there is no point having 80 or 100mm of travel if your only going to drill holes through 50mm timber.

Step 4: Mortice Head Assembly

You will need:
1. m8 bolt 45mm long
4. m8 bolts 80mm long
2. m8 bolts 25mm long
8mm spring washers
8mm washers
3 spacers 8mm id 12mm od 25mm long

Take the handle side, mortice head plate and put 2 of the m8 X 80mm bolts in the 2 holes at the back of the plate then lay it down with the bolts sticking up. Place a washer and spring washer on one bolt. (in that order not the other way around) then a bearing. check now that the bearing is running on the flat surface of the 50mm X 50mm box and not half on the radius, if it is add another washer before the spring washer until it is running on the flat surface (if this is the case you will need to reduce the size of the spacer).
On each bolt you need to place:
washer/s - spring washer - bearing - spacer - bearing - spring washer - washer/s.
Then put the other side plate on top and put a nut on each, dont tighten yet just put them on to hold everything in place.
Now you need to do similar where the slots are except you need to place the tensioners there too. So that will have the following:
tensioner - head plate - washer/s - spring washer - bearing - spacer - bearing - spring washer - washer/s - head plate - tensioner.
the m8 X 45 bolt is threaded through the handle hole from the inside so it is sticking outwards and locked in place with a washer and a nut.
Next take your chisel clamp and secure between the head plates using the two m8 X 25mm bolts with a spring washer on each place the last m8 X 80mm at the front hole and secure in place with a nut, again dont tighten it yet.
Slip the tension brace over the threaded tensioner and secure in place with a spring washer and nut, once again dont tighten it yet.

Get the base and clamp a bit of wood onto the upright leaving about 300mm clear, this will stop the mortice head from dropping too far and prevent possible injuries. Place the mortice head over the upright and allow it to rest on the wood.
now tighten the rear two bolts and the one going through the tensioners followed by the tensionersthemselves if all is well it should be clamped in place but only just so. loosen the two rear bolts and the one going through the tensioner slowly, about .25 turn at a time checking for movement. once the head is able to move up and down place locknuts on each of the bolts. let the mortice head rest on the wooden stop.

Step 5: Motor

You have a decision to make now so I will go though the options I can think of and welcome any other suggestions.

What I did.
was to put the motor on the piller drill and opened out the hole in the center of the shaft by 1mm at a time until it was large enough to take the shaft from a broken cordless drill. Then I held it in place by welding it. You will notice too that I have used a keyless chuck, this isnt ideal as its difficult to get you hand around the chuck to undo it so I suggest that if your using a chuck then use a key chuck.
It didnt turn out too bad chuck runs ever so slightly off centre but I still wouldn't suggest this way, If it went too badly wrong you would ruin a perfectly good motor. This wasnt a worry for me as I had quite a few motors hanging around.

Get a chuck boss made.
Or make one if you have a lathe capable of screw cutting. A bit of round bar with the correct opening for the motor shaft and a thread to screw a chuck onto it. This i think is the best way to do it but dont make it too long or you will not be able get the augers seated properly in the chisels.

Use sleeves.
This would still require the use of a lathe, if you have access to a lathe best to do the above. However if you dont have screw cutting capability then this is a good solution simply make sleeves with holes for all the different sized auger bits you have on one end and motor shaft size the other the use grub screws to secure the sleeves and the augers in place.

So once you have made your decision bolt your motor ring to the motor and place it on top of the mortice head. Clamp a chisel into the chisel clamp and make sure it is square on the machine then fix the auger bit into the chuck/sleeve. Position the motor so the bolts are located either side of the mortice head plates and not in the middle. turn the motor by hand ( it might be a good idea to remove the cowl to do this easier) and check that the auger turns nice and smoothly within the chisel. Once your are happy then tack one side of the mortice head plate to the motor ring, remember to protect the motor, chuck and mortice chisel set from spatter. turn the motor by hand again to make sure nothing has moved. If you are happy then go ahead and tack the other side. Now remove the chisel and unbolt the motor and remove the mortice head from the base. clamp the motor ring to a flat plate to prevent excessive distortion and weld it up.
Once it has cooled you can place it back on the base resting on the wooden stop but dont replace the motor just yet.

Step 6: Putting It Together.

Get the depth clamp, which you should have welded up and made to fit nicely over the base upright. and place it over the upright with the m8 bolt sticking out handle side.
Fit the linkage onto the handle and secure with a washer and a locknut. Now fit the handle and the linkage onto the bolts sticking out of the mortice head and the depth stop you may need to add a washer or two on one of these to get everything lined up properly but once your happy they are lined up put a washer and a locknut on each. These need to move freely so dont over tighten them.
Remember I have only given suggestions for the spacing of the handle bolt holes you can place them where it is best for you required mortice head travel.

You can now go ahead and lock the depth stop in place and put the spring on.
Bolt the motor back on making sure that the heads of the bolts are on the underside otherwise they will interfere with the handle.

I finally get to the fence and hold down. For me this was a bodged solution to do the job I needed done at the time and I have as yet not put much thought into it, so I am just going to mumble my thoughts to you and allow you to work it out for yourselves until I can add something better.

On the base there is a space of 50mm between the 76mm X 38mm channel and i am sure a block could be made that would not only allow a threaded bar to set the position of a vice but also allow a way to hold the wood down to retract the chisel. this would probably require welding a part into the front of these channels to take the threaded bar.

So now I think i am just about ready to put this up and hopefully it wont attract too much derision from the expert iblers, However I welcome constructive critisism and suggestions for improvement.