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Calling all wood workers....again


rplace

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I think I am making this harder than I need to. Given I only have these tools on hand and I want it done now:

  • Jasper Circle Jig (no problem cutting/recessing any size hole)
  • 1/4 inch straight tip router bit that is not long enough to cut through entire speaker baffle, but leaves a nice flat surface behind
  • 1/4 inch spiral router bit long enough to cut through speaker baffle but does not make a nice flat surface

 

The Jasper jig uses a 1/4 router bit meaning it takes off 1/4 inch of material at a time. I want a 15 3/8" outer circle with a recessed lip of 11/16" and a hole all the way through of 14". The recess and lip is on the back side (not that it makes a difference) to mount the speaker form behind.

 

How best to pull this off? Do I just keep taking off a 1/4" at a time, at desired depth, starting with the 15 3/8" for the recess? Once I get to 14" swap bits and cut the 14" hole? If so that would be:

  • 15 3/8
  • 15 1/8
  • 14 7/8
  • 14 5/8
  • 14 3/8
  • 14 1/8
  • Cut the 14 inch hole because the 1/4" bite will remove that last 1/8th above in last step of recess

 

 

 

 

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A bit more noodling in my head and I half way think I only need to make 3 passes at 1/4" each. Am I correct that since 3/4 is the same as 12/16 and I only want 11/16 lip/recess that if I had the remaining 14" + anything it goes away with the 14 inch hole?

 

14 11/16 + 11/16 = 15 3/8

 

So 15 3/8 minus the 3 passes of 1/4 each leaves me 14 and 5/8, right?

 

Starting to think metric might actually be easier for this job.

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1 minute ago, JJkizak said:

That many passes kind of make my nerves rattle.

JJK

 

Me too, seems like a better way. While the jig is pretty tight I can see it not getting a perfect 1/4 ever time, especially  with more passes. Jasper has a formula for different sized bits...ie taking off more than a 1/4 at a time. But requires modifying the existing hole in the jig. Not a huge deal as it is plastic. I have a 3/4 inch straight bit as well.

 

@Rudy81 and @314carpenter These guys should probably be laughing at my question already

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1 minute ago, CECAA850 said:

I use my Jasper Jig to recess or flush mount woofers.  All you need to do is router out the recessed portion first.  Once that's done just router out the hole cut out.  Don't over think it.

 

Right like my 2nd post. Get as much a you need for the recess ONLY then cut the hole because the rest will be gone anyway.

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1 minute ago, CECAA850 said:

The Jasper jig doesn't necessarily take off 1/4" at a time but it CAN take off 1/4" at a time.  It all depends where you put your peg.

 

Yes, but it is configured for the outer most dimension which in my case is the easy part for 15 3/8. I could do a pass at 15 3/8 and another at 14 11/16 but that would leave stuff in the middle. Need to get the entire recess before making the "hole" or you lose the ability to use the jig. If I had an 11/16 bit I could use the formula for non-1/4 bits but I don't have that 3/4 is the closest. I think one pass with a 3/4 bit properly configured for 15 3/8 then the 14" hole would do it in two passes. Agree?

 

Wondering now if better to make 3 passes with 1/4 or 1 with 3/4. Guess the 3 passes with 1/4 don't all have to take out 1/4 each could make them overlap to net 11/16 but that seem like even more bother.

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6 minutes ago, rplace said:

 

Yes, but it is configured for the outer most dimension which in my case is the easy part for 15 3/8. I could do a pass at 15 3/8 and another at 14 11/16 but that would leave stuff in the middle. Need to get the entire recess before making the "hole" or you lose the ability to use the jig. If I had an 11/16 bit I could use the formula for non-1/4 bits but I don't have that 3/4 is the closest. I think one pass with a 3/4 bit properly configured for 15 3/8 then the 14" hole would do it in two passes. Agree?

 

Wondering now if better to make 3 passes with 1/4 or 1 with 3/4. Guess the 3 passes with 1/4 don't all have to take out 1/4 each could make them overlap to net 11/16 but that seem like even more bother.

I make my outer pass and use enough passes to get the correct depth then move the peg 1/8 or 3/16 and start working my way in.  You're not an engineer are you?

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12 minutes ago, CECAA850 said:

You're not an engineer are you?

 

Maybe, UofM college of Engineering seems to suggest that. Seems like it is my personality. I'm more of a visual learner. I see it and understand it right away. Beyond that I tend to overthink things.

 

I've done this several times before on regular plywood or MDF and used my Bosch circle thingy. I just used a compass to make the outer most circle. Selected the bit I wanted for recess witch and visually lined up the outer edge of bit to the circle drawn on the material. One pass and the recess was done. Another pass with the spiral cut at the edge of the recess and the hole was done. No real measuring beyond the size of the outer most circle.

 

This time around I've got the baffles all finished in the laminate I want...no room for error and unfinished ply/mdf. Need to get it right the first time and repeat 3 more. Also first time trying to use the Jasper over my Bosch. The Bosh is more or less like a beam compass. Just two rails that attach to the router base and a pivot point at the other end. I like the jasper better until....the the fractional math of 15 3/8, 11/16 and 14 came in. Along with the 1/4" bit.

 

I see what you are saying with moving the pin it a bit at a time till "you get there" but that seems lazy to me on the surface 😉. Perhaps in this case lazy is faster then endless calculations.

 

Here is how the Bosch is set up....but the jasper's pin is more exact in my mind. Downfall of the Bosch is the taped in place alignment part, but it has never failed me.

vkbellis-albums-photos-used-article-bosc

 

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24 minutes ago, rplace said:

Beyond that I tend to overthink things.

 

 😉

 

Jasper jig is pretty much foolproof.   No need to use anything else.  Practice once on a piece of scrap.  You remind me of another good friend who suffers paralysis by analysis.  Lol.

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I have used various Jasper jigs for all my driver cutouts, including my 18" OB cutouts.  I do not use a 1/4" bit. Jasper includes formulas for using larger diameter bits.  I use a 3/4" bit.  I make my first pass on the largest diameter cutout which is the recess for the driver face.  I then make a second pass just inside of that since most drivers' lip are larger than 3/4".  Once the lip is complete, I use the same bit to make a full cut through the panel to allow the back of the driver to sit flush with the lip I created. Hope that makes sense.

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1 hour ago, Rudy81 said:

I have used various Jasper jigs for all my driver cutouts, including my 18" OB cutouts.  I do not use a 1/4" bit. Jasper includes formulas for using larger diameter bits.  I use a 3/4" bit.  I make my first pass on the largest diameter cutout which is the recess for the driver face.  I then make a second pass just inside of that since most drivers' lip are larger than 3/4".  Once the lip is complete, I use the same bit to make a full cut through the panel to allow the back of the driver to sit flush with the lip I created. Hope that makes sense.

 

Happy New Year! Rudy. Anything special to enlarge the hole in the Jasper Jig? Maybe a 1" Fostner via drill press? Guess it does not have to be perfectly centered since that will be handled by the placement of the Jig on the router base. I hate to cut it up, but thinking 1 pass with the 3/4" bit will do the recess nicer than multiple with a smaller bit.

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Happy New Year.  Assuming I have made sense, The first two passes, making the recess for the driver lip, I just use a plunge router to the exact depth I want.  Since I use 18mm BB, it takes a couple of passes increasing the depth until I get where I want.  Once the 'lip' is created, I start making the passes that will eventually cut all the way through the board.  I will say that I am not familiar with the jig you showed in the picture a few posts up. 

 

I have a sneaky suspicion we are not talking about the same thing since you mention a drill press....

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4 hours ago, rplace said:

 

Right like my 2nd post. Get as much a you need for the recess ONLY then cut the hole because the rest will be gone anyway.

 

Didn't Paul say that it doesn't make any difference in the sound to recess the woofers?

JJK

 

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Addressing the picture you posted above and ASSUMING you can keep the 'taped' pin in place....this is how I would do it.

Set the plunge stop the depth you want for the driver lip.  Start at the largest diameter necessary for the driver to drop into place.  Make your first circle to the depth of the lip.  Move the jig a little closer to center to increase the width of the lip you are carving until you get the correct lip width.

 

Finally, set the jig to the diameter necessary to drop in the basket and cut all the way through.

 

Again, assuming your taped pin will not move, which is a big IF.

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4 minutes ago, JJkizak said:

 

Didn't Paul say that it doesn't make any difference in the sound to recess the woofers?

JJK

 

I don't recess the driver due to acoustic differences.  I do it for several reasons.  First, it presents a nice flush look, which may be necessary if you are putting a grille on the face of the cabinet.  Second, it makes it easy to keep the driver in the exact same place when measuring and drilling holes for T nuts, which is a big deal when working with very large, heavy drivers.  Finally, because I can and it looks nice to me.  It is more work of course, but messing around in the wood shop is not like work for me.

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