Hi JH and Jose,
It was very easy to make, starting with an MT2 arbor as shown at the top of this page
http://www.arceurotrade.co.uk/Catalogue/Blank-End-Arbors (mine was 1.5”, or 38mm).
1. On the lathe, with the arbor in an MT3/MT2 adaptor, drill the centre hole already present in the end of the arbor to a greater depth, to give a rough idea of where the centre was after step 2.
2. Saw off the bottom at a 20º angle (with hindsight, I should not have done that)
3. Grip the flats in the milling vice, with the sawn edge approximately horizontal, and clean up the sawcut.
4. With the job still in the vice, mill out the offset tool slot, 6.5mm wide and 6.5mm deep (to allow for both 6mm and ¼” square tools). I drilled a line of holes first, so the slot-cutter would have less work to do.
5. Replace the job in the vice with one of the flats on parallels (actually, I don’t have any parallels, but for this job anything which is fairly parallel will serve), mill out two slots for the heads of the Allen screws to clamp the tool, then drill and tap M5.
6. Clean the whole thing up.
When I ran the flycutter over about 300rpm, vibration began to set in – hence my first post. Subsequently, I searched the floor for 20 minutes, and finally found the piece sawn from the bottom in step 2, cleaned up the sawn side and bolted it back on with M3 Allen screws, to produce this:
Yesterday, I cleaned up a length of 2” square aluminium tube at about 800rpm for the finishing pass. Very little vibration, and the finish was acceptable.
What I
should have done after Step 1 was not to have sawn off the end at an angle, but just mounted the job in the vice at a 20º angle for cutting the slot in Step 3. This would have reduced the imbalance to that caused (a) by the tool itself, and (b) by the wedge of missing metal below the tool at the end where the slot was deeper. Mike of
http://mikesworkshop.weebly.com/ suggested a simple cure for (b) : a wedge of steel pinned in place to fill up the gap under the tool.
Andy