port cut-out

[dawg1161]

hello to all. dumb question for you but this is driving me crazy. i am building the dayton III project so far i haven't managed to mess anything up by trying each step on scrap before i actually do it to my cabinets. i am using the 3"i.d. pvc that the plan calls for i have measured the pvc at 3 1/2" for the cutout so when i use my 3 1/2" hole saw its bigger than the pvc. anyone have the exact cutout size? today i will practice with the jasper jig. i have used it but it seems to be an 1/16" off when i made my first cut with it.
other than that the project is comming along real well with everyones help.
again thank you all.

[oxcartdriver]

I too was off with the jasper jig slightly on the second and third practice cut outs. Turns out that the screws holding the jig to my router had become just slightly loose. I torqued to a slightly highier spec and had no issues routing the facia multiple speakers in a row.

[BobEllis]

Here's how I do it:

Rout a hole for your 3" port tube in a piece of MDF, then cut it to 4" x 4" or so.

Insert the port tube to this piece of MDF, with the tube flush with one surface. A few dabs of hot melt glue will hold it in place for now.

Drill a hole in your cabinet where you want the port - a 2.5" hole saw would be great.

Glue the tube/flange assembly into the cabinet, centered on the hole you just made.

Use a flush trim bit to remove the excess mdf in the port hole once the glue sets.

You'll now have a smooth but sharp edged port. Use a roundover bit if you prefer - remember that a large roundover may change the effective port length. (Don't forget to account for the thickness of your cabinet when determining port tube length) The hot melt makes it fairly easy to pull the tube and change its length. Once you have it right glue the tube in place.

This method is a bit more forgiving of not-quite-right port holes than making the hole in your cabinet.

[collo]

My method is much the same as Bob's but has some drawings as well.....

http://www.users.bigpond.com/bcolliso/flares-10mm.htm