Advice Wanted On Fly Cutter

[Brian Brightwell]

I have been working on my new dust collector and need to make about 15 blast gates. To make these I will need to make four, six inch holes it one inch plywood and plexiglass, 60 holes altogether. I could rough the holes out with a jig saw and then use a pattern bit in a router for final size. Or how do you think a fly cutter in a drill press would work? I think the actual size will be about 6 1/4 inches. Does anyone have experience with a cutter this size in one inch wood?

[Harry Niemann]

I think this will load down your press too much. The belt will slip.The larger the diameter the more torque is required

[Michael W. Clark]

I think this will load down your press too much. The belt will slip.The larger the diameter the more torque is required

I would tend to agree based on my experience. I haven't cut any holes that big with my fly cutter, but the belt did slip and had go very slow on the feed rate. If you could gang the pieces together for triming with a router, it would probably be faster.

[Don Stephan]

Use the router.

[Stephen Cherry]

A pin router could do this super fast; a normal router would do it normal fast.

[Norman Hitt]

Brian, I made several Blastgates using 3/4" Melomine for the sides and tempered hardboard for the slide. I cut two different size holes for the inlet and outlet of the gates to fit in a 6" PVC Collar in one side and a short piece of 6" PVC pipe in the other, and all cuts were made with a flycutter. I just used gentle pressure and the cuts were still very quick, clean and smooth and the PVC fit perfectly. (No belt slippage or any other problems). The hardest part was finding a flycutter that would cut that diameter, but I finally found one. I can't remember if that one came from Sears, Ace Hardware, or somewhere else, because I also have two other smaller ones. I made a jig to use my tablesaw to cut a small groove around the outer diameter of the PVC to give the adhesive some bite on the PVC. In each piece of the PVC, I left them a little proud of the inside surface of the melomine and then when the glue was dry, I used a roundover bit to trim the PVC 4 sheets of paper thickness proud of the inside faces of the melomine, and they worked perfectly, (both sliding and sealing on the suction side.
Hope this helps.

[Phil Thien]

I have a General Tools fly cutter that will do 8". This thing demands respect.

The cutter on it tended to dull rather quickly. I purchased a carbide lathe carbide insert kit on eBay for about $20. It came with five (I think) different profiles, the only one I really needed was the outside cutter. The beauty is all five of the carbide tips are interchangeable, so I have five carbide cutters that I will have to exhaust before I need a new one. And they last forever.

Just be careful to clamp your work well and respect a fly cutter working at that diameter.

[Steve Rozmiarek]

Not what you asked, but those hole saws for recessed lighting are usually 6 3/8", Greenlee makes one with a replaceable blade too. Just another option. Fly cutters never seem to work right for me.