Only a Plunge Router? QQ

[evanc]

Whiteside bits are excellent. You probably need flush trim and template bearings for much of your work. The spiral bit you linked to is an upcut. When cutting plywood a downcut will leave a better surface on the side facing the router.

[RonVinyl]

Originally Posted by evanc

Try to get 1/2" shank bits. Larger diameter cutters with bigger bearings last longer. I like the shear cutting bits. Make sure you understand the concept of climb cutting and be sure to avoid it.
Evan

If I recall correctly: climb cutting is when your are going against to rotation of the bit and forcing the router to go in the direction it does not want to. This could not only cause poor output in the work but also kickbacks etc?

[RonVinyl]

Originally Posted by evanc

Whiteside bits are excellent. You probably need flush trim and template bearings for much of your work. The spiral bit you linked to is an upcut. When cutting plywood a downcut will leave a better surface on the side facing the router.

Good to know about the downcut.

I need to flush mount my drivers, should I do it all with the downcut bit or should I cut the hole and then use a rabbet bit? (I have a jasper jig in order to do the circle cut.

Thanks!

[evanc]

I'm not sure how the jasper jig works. I usually make 2 patterns in 1/4" or 1/2" material for the two size holes I need for the driver. Then I lay these on my real baffle and follow the pattern with a pattern bit.

About climb cutting, this is tough to explain in writing. Looking at your router in place and ready to cut the bit is spinning clockwise. If you are routing the inside of a circle you need to work in a clockwise direction. The direction you move the router will be the opposite if you are working the outside of a project. Think this if the router bid starts to work like a wheel and drive itself around the work you want it to move into a spot where you have already cut the material away. If the bit runs into fresh material it will grab and might get away from you and could ruin your work.

Evan

[wintermute]

I use 1/2" Straight bits for my hole cutting. I have a half inch router with a 1/4" adaptor collet. My 1/2 staight cut bit is actually a cheapy 1/4" shaft one that I bought in a box of 12 bits and it has cut quite a few holes so far!

I made my own circle jig, but it works similarly to the jasper jig. I proceed as follows:

1. set the depth of the bit measuring with a strait edge from the router base to the tip of the router bit (set for depth of rebate).
2. using the circle jig set the radius for the size hole you want for your rebate and cut out a circle to that depth in some scrap wood. Check that the actual cut depth is the depth that you want. If not adjust and test again.
2A. You might at this point want to cut the inner hole in the scrap wood to make sure that the rebate depth is really correct with the driver mounted. if it is great, but you will need to repeat step 2 again, as you have just lost your depth setting...
3. once you are happy that the depth is correct cut the real driver rebate in the baffle.
4. Set the radius for the inner hole and once again cut down to the depth that the rebate was cut.
5. depending on thickness of the baffle set the depth to either the rest of the baffle thickness or somewhere in between. and cut again. repeat until all the way through.

Doing multiple passes for the final cutout hole is kinder on the bit and you are less likely to burn the wood. It also (with my router at least) means that the dust extraction works better and I get a lot less dust everywhere else.

Tony.

[RonVinyl]

The driver is 207mm, removing the inside diameter (168mm) gives me a total of 39mm.
Cut that in half and I came up with this rabbet size:

- 19.5mm rabbet width
- 10.6mm rabbet depth (there is a 1mm gasket which I am to assume should be compressed which is why I made the depth 10.6 and not 11.8)


Here is the link to the plans that I will be following: http://www.madisound.com/pdf/PensilsA122p-191012.pdf

[RonVinyl]

Also: Going to grab this bit today.
Buy Whiteside RD5100 Standard Down Cut Spiral Router Bit 1 2 D X 1 CL 1 2 SH 3 OL at Woodcraft

[wintermute]

Oh and one thing. Not sure how the markings on the jasper jig are, but your radius will be dependent on the size of the bit you use! Because I made my own I just adjusted for the size of my bit.

I just looked at the plan, it says that the gasket has little to no compression... Also check what the recommended cutout size is from the drivers spec sheet, it may not be as tight as 168mm...

With the 19.5mm rabbet width, you will probably need to do two passes. The 207mm one is the critical one, you can just set for a smaller diameter to get the rest.

Tony.

[allentodd]

Hi Ron -- you may already be done with your super pensils, but I wanted to point out a couple of things that I encountered when I built the standard 7.3 pensils last year, as my first speaker build. With the mark audio alpair speakers, it is considered a best practice to flush mount, which I see you are doing, but to back of the baffle should also be chamfered to reduce internal reflections from the driver back to the cone. you can either use a 45 degree chamfer bit, or a hand rasp.

Secondly, the stability of the jasper jig depends on having the peg in the center hole -- once the waste is cut from the center you cant use it anymore. So don't cut the through hole first -- do your rebate first and finish up with the through cut. Also if you are planning to finish with veneer, it is *much* easier to apply the veneer first and do the cut once rather than applying the veneer over the hole and trimming (as i learned the hard way). I ended up cutting a circular hole in a piece of scrap to use a template and trimming the veneer with a flush trim bit, but more experienced wood workers might have better techniques...