Although a chisel could perform the cutting perfectly well I decided to use a router as it should offer me greater flexibility.
The router I used was a standard ~89mm diameter body, fixed base router. Almost any router could be used but a fixed base router allows for really simple mounting. Here I am using the template to cut out the router mount at the bandsaw.
To insure that the M8 bolts align properly I drilled through both the top and bottom of the mounts at the same time.
By referencing off the front edge of the carriage the mounts can easily be aligned to an sufficent level. I used the same brad-point drill bit to mark where I needed to drill. Once the holes in the carriage were drilled, it is a simple matter of bolting the router in place, being careful not to over-tighten the mounts.
The follower “arm” is what holds the bearing follower, used to reference off the templates. This part of the jig needs to be ridged to work best. To ensure this was the case I joined the parts with a bridle joint, using a really simple jig to hold it steady at the tablesaw. A mitre guage was used to cut the shoulders of the joint.
As an insurance measure, once the joint had dried I drove two screws through the joint to hold it permanently together. In the plans I drew dowels for this; but I came to the decision that the additional effort was not necessary for what is, a workshop project.
The follower itself fits to the follower arm with two bolts. The follower is constructed from a short length of 25mm aluminium angle. On one face are two holes for the bolts which fix the follower to the arm and on the other face a single (threaded) hole to attach a bolt, which holds a bearing. The bearing size corresponds to a matching diameter round-nosed router bit. As the bearing is fixed to the aluminium angle with a bolt, it can be raised and lowered to exactly the right height for the template.
Having each bearing attached to its own mounting bracket makes for quick follower changes.
Here is another follower which I made for a 3mm round-nosed bit, which should also work for V-groove bits. As bearings so small are neither available nor practical, I simply glued a length of coat hanger wire to the aluminium angle, which was the same diameter as the router bit.
The follower “holder” (the part which fixes the arm in place) is really very simple. Made from two pieces of MDF they are screwed either side of the “arm”. To prevent any play (or slop) of the arm I sandwiched the arm between the holder whilst I screwed them in place, this seemed to work very well.
Here I have drilled out the counter-bores for the heads of the M6 coach (carriage) bolts, these allow one to clamp the arm in place. (Can be seen used in the video)
The “zero stop” (explained in the video) was produced by making a series of passes at the tablesaw.
The slot through the zero-stop, was cut at the router table. If you do not own a router table you could always drill a series of holes with a brad point drill bit, then use a chisel to smooth out thew slot.
I didn’t cover the lathe mountings during the video as it did not seem that interesting. I also did not include drawings in the plans, as I felt that every lathe is slightly different and hence drawings would be of little use. Bellow I demonstrate how I mounted the duplicator to my lathe, this method should work for a number of different sized lathes, although this exact method would not work for mini lathes, due to both the weight and height of the duplicator.
The mounts consist of two flat lengths of pine which rests on top of the bed of the lathe, the duplicator can then sit on top of the mounts. (I used two bolts on each mount to prevent the duplicator from slipping on the mounts.) The duplicator will then need to be raised to the correct height (where the centre of the router bit matches the centre of the lathe) shims can be used for this. Conveniently in my case this only required a single piece of 12mm plywood to achieve.
The mounts are held to the bed of the lathe with a single bolt on each . I cut a slot in the mounts which the bolts can slide in, allowing one to align the duplicator, so it sits parallel to the lathe.
I demonstrated this procedure in the following video: Click Here
The bolts hold the mounts to the bed using the same cast pieces of metal which usually hold the tool rest to the bed. My lathe was supplied with a few extra of these which I was able to use for this, but I would imagine that they could be made by gluing a couple of pieces of plywood together instead.
The dust guard was not something which I covered in the build video as I am not certain how much protection it truly serves. The guard helps to enclose the draw slides, in order to prevent wood chips from the lathe, from “jamming” up the slides. The guard overhangs the front edge of the duplicator enclosing it well there, but as both the bearings and slides interfered with any dust shield I placed at the back, I had to remove it and hence it is not contained in the plans. Because there is no back guard (where most chips would likely enter anyway) the dust guard in my opinion is of little use. That being said if you did happen to come up with an alternative way to protect the draw slides from dust, I would be interested to hear it!
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