Finally I'm able to get my 17.5" project under way.
I need to cut a series of 50mm diameter holes into 15-30mm plywood. These need to be accurate as they will be holding the truss poles in place (there will only be three truss poles). Hole saws are no good- too big. I have both a drill & a router. Any suggestions?
Keep your tool speeds high, your feed rate low (watch out you don't burn it though) and your work firmly clamped in place so it can't possibly move.
Where you can, use a template or guide and if in doubt, test it first on a scrap piece of wood, the same material and thickness as you are going to use.
I know I don't have the capacity to handle a 50mm forstner bit.
For a pattern follower bit, wouldn't I need a substantially deep template to engage the bearing? Might be better to use a template for the router to trace, wouldn't it?
I've seen two types of templates/jigs for tight circle cutting: the 'Jasper Jig' type commercially made or DIY, and the circular hole template for the router's base to trace. Which would be a better option?
There is a "51mm" hole saw in my set. It is actually 2" as it is an imperial set. They weren't particularly cheap, but then no Sutton tools are.
Your local tool shop might also have metric ones if 2" isn't close enough.
You drill from one side most of the way through (until the pilot drill is all the way through), turn the timber over and finish from the other side. No surface splitting. 500rpm recommended max speed.
I'm sure you'd find other uses for the hole saws, like making wheels for toys, so you could amortise the cost.
I know I don't have the capacity to handle a 50mm forstner bit.
It is possible to use a 50mm bit in a handheld drill but a drill press would be neater and easier (not to mention safer)
For a pattern follower bit, wouldn't I need a substantially deep template to engage the bearing? Might be better to use a template for the router to trace, wouldn't it?
I've used routers with a template to cut holes but nothing that small. There's also the issue of making a suitable template which needs the capacity to cut an accurate hole to start with.
I've seen two types of templates/jigs for tight circle cutting: the 'Jasper Jig' type commercially made or DIY, and the circular hole template for the router's base to trace.
Jasper jigs are intended for large holes, 50 mm may be too small to get an accurate cut.
Which would be a better option?
Using a CNC router would be the best way. Can;t help with that though
I very much like Sutton tools. I have one of their drill sets, beautiful.
The aluminium poles I'll be using are 50mm (just how close to 50mm I find out on wednesday when I take delivery of it). These impirical hole saws might make the fit too sloppy I think, especially after sanding & finishing.
I've seen one and two arm hole cutters to fit a drill press. Are these also an option or would I be asking too much of these tools to cut through a lot of 15mm hardwood ply?
You know what I would do (to save a lot of messing about) I would make an accurate drawing of what you want and take it to a water jet cutting place.
I do this a lot, the results are awesome.
Dave's right. Waterjet or laser cutting (or CNC router) will do a quick, accurate job on cutting the pieces to size and drilling all the required hole.
You'll need to be able to provide a suitable CAD file of what you want to cut/drill.
