Workshop Wednesdays - Chamfered Mouldings on your Thicknesser archive
Wednesday 3 December 2014
Martin Howlett shows you how you can achieve any angled chamfer on one jig
This is a really useful jig for making angled moulds and fillets from square stock using the planer/thicknesser. It enables the user to control the work piece so a consistent finish is achieved. I've found this particularly useful when I'm in a rush, as we all know we can often leave these bits and pieces right until the end of a job when time is against us.
Some things to remember when making a jig are, don't rush and leave it to the last minute. Treat it like the piece of furniture you are making, ensuring accuracy and attention to detail. At first it may seem like a day wasted, but once a jig is made you have it for a long time. To save money use off-cuts where possible for the construction, but select them carefully. Many jigs are suitable to be made from MDF, but like solid timber, a bowed piece of MDF can just as easily compromise the finish on the work piece.
To make this jig, the first thing to do is assess the planer/thicknesser. Make an accurate measurement of the machine bed - length and width. Ensure that the baseboard of the jig will fit between the guides. If your thicknesser has a wide bed I would suggest making your jig approximately 300mm wide. The jig doesn't have to run the entire length of the bed, however it's important it clears the in/out-feed rollers by at least 150mm. Produce a cutting list with the following components in mind, you'll need two pieces for the base boards, one for the fence and a piece for the stop. The baseboard needs to be 150mm longer to allow for the stop.
Drilling for boltsFirstly mark out the holes and slots for the bolts. Measure in 40mm along the long edge. Space out four bolts evenly. On a meter long jig, three bolts should be enough but air on the side of caution and use four to prevent the board from flexing where there's less support. More bolts will transfer pressure from the feed rollers and cutter block to the baseboard. With a pillar drill cut a 8mm hole through both pieces. Using the holes as a guide, mark the slots and cut these on the bandsaw. Make sure they're neat so that it will run true with the bolts.
Align the baseboardsOnce you're happy with this, fit the butt hinges to the base and top boards. Attach the bolts from underneath the baseboard and secure them from the top with a washer and nut. At this point ensure that the two boards fold onto one another exactly in line, if they don't it's important that this is adjusted now.
Attach the fenceThe fence needs to be screwed to the work piece board, make this approximately 100-150mm. This really depends on the size of stock you're likely to be making. The wider this is the less usable space you have but it will enable a deeper cut to be made. In other words, smaller fillets can be machined. Secure the stop underneath the base board approximately 100mm from the front, this secures the jig on the machine bed.
Operating the jigSet the jig to the desired angle using a bevel or protractor and use the nuts to secure into position - It's easier to lift the flap clear of the nuts and move them to a rough position. A metre rule can be put across to check the line. Bring the board onto the nuts and make small adjustments to ensure it's supported. It's really important to ensure all nuts are in contact.
Depending on what thickness material you have used to make the jig and the size of stock you're using will determine at what point the machine will start to cut. A fail-safe way of checking is to wind down your thicknesser some distance. Put the jig into the machine and push your work piece onto it. Gently wind the bed up until the stock just touches the feed rollers. Wind it back a couple of mm and pull out the stock piece. Before the first pass, check that nothing is in contact with any moving parts.
To make the first cut raise the bed approx 4-5mm and then make a pass with the stock. A feature of this jig is that the first few passes are hardly noticeable. The amount of material removed in each pass increases as the machined area spreads across the stock. Be sure to continue with small cuts to maintain a good finish.
AdjustmentsIf you need smaller stock and the fence fouls the cutting block, just add a packer with a stop on, much like a board you would use for running out thin stock in the normal way. This gives more height to the work piece and prevents the rollers/cutter block hitting the jig.
There are various permutations to be experimented with. The width of the fence can be changed and packers can be placed on the working surface. There are times when you'll need to use shorter bolts so that smaller angles can be cut.
In order to make using the jig more efficient, every time it is used make a stock piece. This way a visual set can be made quickly and simple fine-tuning will get the angle you're looking for.