Purchasing a painting just as a completed canvas makes it very easy to transport. In this case an oil painting brought back from a holiday in Cambodia. However, this means the painted canvas needs to be 'stretched' (i.e., mounted) on 'stretcher bars' before it can be framed and hung on a wall.
Therefore, this project involves three parts: making the stretcher frame, mounting the canvas (picture) on the stretcher frame, and finally, making the actual picture frame.
Making the Stretcher Bars
A stretcher bar is used to construct a wooden stretcher used to mount oil painting canvases. Stretcher bars are usually a wooden framework support on which a canvas painting can be fastened. Stretcher bars are widely available at Art Supply or Hardware Supply outlets, however, such items can be easily made from "scrap" timber from around the workshop.
As shown in the Project Plans Section ("Plan 1: Canvas Stretcher - isometric") the stretcher bars are just a simple rectanglar frame formed with lap-joints (butt joints could be just as easily used, but the lap-joints are stronger).
I used some scrap pine (left over palings from a fence) which was planed down to 10mm thick and cut into strips 20mm wide. These dimensions were based upon making the frame as light-weight and thin as possible, but still ensuring that the frame (i.e. stretcher bars) would not twist when the oil painting canvas was stretched (mounted) on the completed frame.
The particular canvas that was to be stretched was relatively small, so cross supports were not necessary. For larger canvases, further 'cross beams' may be required as necessary to give extra rigidity to the frame.
Stretching the Canvas
There are myriad sites on the Internet explaining how to go about actually stretching the canvas on the stretcher bars.
The main requirement is a sturdy stapler that can 'tack', that is, drive a staple directly into the frame. The cost of suitable stapler (~$20 at a local stationary shop) is much more economical than getting the canvas stretched professionally. And even if you don't have more than one canvas to stretch, a 'tack' stapler finds many uses around the house, attaching things to walls etc.
Many of the internet sites showing how to stretch a canvas also recommend or use a tool designed to stretch and hold the canvas taut to facilitate stapling. However, I found this un-necessary for the small canvas size I was dealing with.
I won't repeat/detail all the steps involved in stretching the canvas (google search - many good sites available with full video), but found it not particularly difficult, make sure you staple from the centre of each side of the frame first, and take your time.
Making the Picture Frame
As shown in the Project Plans Section ("Plan 2: Picture Frame - isometric") the picture frame involves a 'channel' that forms a 'lip' at the rear face of the frame which retains the stretched canvas.
I wanted the frame to be as light weight as possible for hanging on removable picture hooks. The scrap pine being used is fairly soft and can be damaged relatively easily. So I chose 5mm thickness for the retaining 'lip'. The stretcher bar for the canvas was 10mm thick, therefore, the frame needed to be a total thickness of 15mm.
The oil painting in question is relatively small in area, so a relatively wide picture frame would add to the aesthetics. The wood grain in the pine was also rather attractive, and gave a pleasing 'rustic' look that suited the 'jungle' theme of the painting. This lead to a width of 35mm being selected for the frame.
The scrap pine available, palings from an old fence, was ~2m in length, from which a strip 35mm wide was cut. Then a 'channel' was cut into one side of this cut strip, 5mm deep, using a few passes on a table-saw. The required pieces of the frame were then cut from this dressed, formed strip of pine, using a mitre box and saw, cutting 45o across the width (see "Plan 3: Picture Frame - Detail, Bottom View" for detail diagram showing the 'channel' and 'lip' etc). Straight perpendicular cuts could be done instead of the 45o, however, the angled joins were judged to be more aesthetically pleasing.
The four (4) side pieces of the frame were then glued, using framing clamps to ensure the frame would end-up being 'in square' when completed. While waiting for the glue joints to dry, the work piece was laid flat on the work-bench to ensure that no 'twist' would develop.
After all the pieces of the frame were glued, the work-piece was sanded with successively finer grit sand-paper, and then 'painted' with a clear gloss varnish. Three coats of varnish were used, which turned the pine a deep 'orange-brown' nicely accentuating the sun-set scene in the painting.