Coffin project additional information Blog

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Blog entry by robscastle posted 05-24-2012 01:47 AM 1713 reads 3 times favorited 0 comments Add to Favorites Watch

Coffin Shaped Box


From what I could find regarding making real coffins is that there is a few dimensions which appear to be uniform. They are, internal height 360mm, wall thickness 15mm and mostly constructed from MDF. The sides appear to be fitted into a groove/rabbet in the base.
Common Sizes. 250mm at the head, 180mm at the foot, 560mm wide at the shoulder and the head has a slope of 5 degrees and the foot 15 degrees the base or bottom is about 12.2mm thickness. If you screw it together the screws should be no more than 200mm apart and possibly glued and nailed as well
Internals need to be waterproof. No sharp edges

To make a custom made coffin it appears that you need only add from the intended persons size, 100mm to the shoulder span and 130mm to the standing height.

Tools and Materials Required
For this project I used the following:-

1x sheet of plywood being 5 Ply at 12mm thickness.
1 x nylon framing Clamp
1 x Air Nail Gun (optional)
Polyurethane Glue
1 x Table saw
1 x Adjustable bevel
1 x Adjustable protractor
Notes from the internet (Optional)
1 x pliers for pulling the staples out of temporary braces (optional)
1 x pencil
1 x electronic level
Various scrap bits as a prototype from a recycled plywood packing box (optional)
1 x Sheet of tracing paper
1 x Bench Sander
1 x Router/trimmer
1 x Parallel router bit with a bearing on the tip
1 x Piano Hinge and suitable screws, style constructors choice.
? x Handles quantity and style constructors choice.
? x Securing catches ( I used Magnets)
Various hand tools screwdriver, drill, Drill bits countersunk etc.

Construction Details
I used a sacrificial (no pun intended) series of plywood parts to develop the Box and made some router jigs.

All the steps involving cutting were prototyped before using the production material, I did this to ensure I cut the correct angles where they were needed first and everything fitted together correctly.
Most of these ended up in the bin as they were beyond further use, and I can assure you I did make some angle cutting mistakes and cut the ply too deep in places. However I think the additional work was worth it for a first off run. Ignore the inlay cross sitting on the framing ply it was just a thought

Coffin Base

Materials 2×230mm x 600 mm of plywood this becomes the base or top.
Note: For the top I used a solid piece of Pine. 1×290 x 600×19mm (see Coffin Top later in the text)

1. Mark a centre line at 115mm
2. Mark a shoulder line at 430mm
3. Mark the base at the foot 60mm in from each side
4. Mark the base at the head 50mm in from each side
5 Draw from the base marking to he edge of the shoulder line then to the head line
6. Fix five temporary blocks 2 x at the head and 3 x at the foot
7. Using a spreader 190mm in length at the shoulder bend positioned at the 430mm and 420mm curve the sides and fit to the blocks at the head and foot.
1 Spreader position

Note: the foot end of the spreader should be on the 430mm line on the base.
The sides must be flush at the head or foot of the base, your choice which way you go.
8. Check the alignment top and bottom and left and right and the spreader is parallel to the 430mm line.

Figure 2 Spreader parallel to the 430 line

Note: One end will be short due to curving out and then in of the sides
9. Using a pencil draw around the outside of the sides and join the curved lie up with the existinglines to mark the finished profile.
Note: There must be at least 10mm on the outer edge all round, this is for finishing trim.
10. This line will become your routing profile guide later.
11. Transfer the line to tracing paper
12. Transfer the line onto material for the routing jig.

Coffin Sides
Materials 2×100mm x 600mm
1. Mark a line at 420mm and 430mm
2. Cut 4 saw slots in the sides four plies deep
3. At the head end cut the ends with a 5 Deg angle sloping out at the top
4. At the foot end cut the ends with a 15 Deg angle sloping out at the top

Coffin Foot end and Head end
1. Measure the ends and add 10mm each side to oversize them, this is for ensuring the heights are long enough after cutting.
2. You already know the top and bottoms will be angled at 5 deg for the Head and 15 deg for the foot.
3. Now the offset from 90 deg for the foot sides is about 5 degs and the head is about 15 deg so these will have to be added to the bevel cuts on the sides
4. I used 60 deg and 50 degs for the sides and then cut the end pieces at 45 deg for convenience. You can please yourself here as to how you calculate the angles
5. Trim both head and foot ends to match the side height of 100mm.

Note: The 15 deg angle for the Foot and 5 deg angle cuts for the Head are parallel on both top and bottom ends.

Glue up
I found the easiest way to hold the parts together was to tack some temporary frames at the top and bottom. This allowed for the splay to be accounted for as well as stopping everything springing apart.

Note: The coffin will appear be marginally smaller at the bottom than the top, (about 4 to 5mm due to the tapered ends. I assume this is a normal design result.

Figure 3 Temporary frames

Finishing the Base
I used a router bit with a bearing at the tip to profile the ply base to the sides, then sanded to parts that required further finishing

Coffin Top
(See Important Note)

For the lid (I decided to use a piece of solid pine as I wanted to cut a taper in the edges) I traced a line from the coffin top leaving about 10mm overhangs all round.
I cut out the basic profile and finished the edges and ends on the sander.
Using my tenoning jig and the saw set to 5 degrees I cut the profile into the lid edges.

Note: 1 I had to gradually increase the depth of the cut as my table saw id is only small (10”/254mm) and it required a reasonable level of skill and care to do this activity so as to stop when the right hand edge of the blade exited the side of the timber.
Note: 2 I reused the off cuts on the hinge side of the lid.

Once I then had the correct height set on the table saw I then rotated the lid and completed the remaining sides/edges cutting the material away from the top.

Important Note: As there were no guards fitted in this cutting operation the material being removed although only small will shoot out towards the operator! Beware and stand to the side.
Otherwise wear a full length leather apron, your lodge one may do, but please don’t damage it or any bodily parts please.

-- Regards Rob

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