|Project by BritBoxmaker||posted 02-04-2011 07:15 PM||5578 views||34 times favorited||32 comments|
This is version 2.0 of my Circle Cutting Jig for the band saw. Its a lot more rugged and accurate, including, as it does, a micro-adjust feature.
The overall size is 750mm x 400mm x 30mm. Materials are chipboard (laminated in three layers) and Beech with a length of M8 threaded rod, various metal and plastic bits. Circle cutting range is from 25mm radius to about 450mm radius. (I’m sure you can do the conversion into inches by now, there are 25.4mm to 1 inch)
This time the pin (with adjustable distance from the blade) is an M6 roofing screw. This is mounted in a sliding section of the table (bottom right of pic. 2) set in an M6 ‘T’ nut. This is detailed in the upper portion of pic. 5.
The sliding table section is held down due to its 15° bevelled sides.
The bottom portion of pic 5. shows the threaded rod which goes the entire length of the jig (This rod is imbedded in a slot between the middle and upper sheet of the chipboard). It threads into an M8 ‘T’ nut set into the left hand side of the sliding part of the table (pic. 6) and is captive at the extreme left hand edge of the jig, where the adjustment wheel is. The scale on the adjustment wheel is from a project by Russ (rmac) and is the only idea in this project that I’ve sourced from elsewhere. Thanks Russ. The adjustment wheel and its guide line are shown in pic. 4.
The M8 thread pitch is 1.25mm. There are 25 graduations around the adjustment wheel making the pin position accurate to 0.05mm. I know band saw blade run-out is greater than this but I will be using this jig for multiple, evenly spaced cuts, from the same workpiece and it is the cut spacing accuracy I am concerned with.
The jig is located into the bed of the bandsaw by a guide rail and clamped in position to the bed when in use.
I realise that all of the above may not be easily seen or grasped and so I may be blogging the build of this jig in the near future if there are many questions.
-- Martyn -- Boxologist, Pattern Juggler and Candyman of the visually challenging. http://www.theartofboxes.com