First attemt to cut driver hole with router.... FAIL!!! - diyAudio
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Old 8th April 2008, 05:16 AM   #1
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Default First attemt to cut driver hole with router.... FAIL!!!

So I just totally botched up my latest little creation. I finally went and got the Sears router jig that Zaph recommends, having cut every previous driver hole with a jigsaw up until now. In the past when I have tried to cut a hole in a baffle that is 1.5" thick, the blade kinda bends without me realizing until after the hole is completely cut, and I have to go around trimming the inside of the hole to make it so the driver can fit, which of course makes for a messy backside of the baffle for hurricane nuts and things to grab onto. I got the router guide and a router bit I assumed (mistake #1) would do the job fine. It was only barely long enough (just over 1.5") to make the cut, but still seemed to cover the thickness of the baffle. To make a long story short, my shop is absolutely THICK with smoke right now. The bit always seemed to be having trouble with the cut, and I had to put alot of pressure on the router to make it move, to the point where I accidentally, without realizing it, slowly extended the dimension of the cut so that when I got around to the beginning of my cut, I was about 1/2" further from center than I started. This is obviously not good, and I am scared to try again without more info. I even experimented and retracted the bit up so only about an inch was into the wood, just to make sure i wasn't forcing a part of the bit that wasn't supposed to be cutting, but it didn't change much at all. Is there some special kind of bit I should be using? Should it be that hard to move it during the cut? Does anybody know of a hole-saw set that goes from 15" down to 3" in 1/4" increments in case I never get this? Any tips from the router-jig-experienced would be GREATLY appreciated.
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Old 8th April 2008, 05:35 AM   #2
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Were you taking the whole thickness in one pass? Try 1/4" depth per cut and you'll have an easier time.
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Old 8th April 2008, 05:43 AM   #3
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Get the Jasper circle jig - couldn't be easier to use, pretty much foolproof. No adjustments to slip.

I got excellent results on my first attempt using a spiral downcut bit and using multiple passes for deep cuts. I would suggest cutting maybe 1/2 inch of depth per pass. The Jasper jig guarantees repeatable results. Screw the plug that will come out of the hole to the sacrificial board and clamp everything in place so the center point won't move when you complete the hole cut. Do the outermost circle for the driver recess first and then work inwards.

Also hook up a vac system to suck all the dust out. I created a poor man's dust collector system out of a 5 gallon wet/dry vac on sale, a couple of 2" PVC pipe fittings and some smaller diameter vac hose to fit the dust port on the router or the radial arm saw.

And stay out of Woodcraft. That store is worse than having a crack habit.
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Old 8th April 2008, 07:45 AM   #4
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Quote:
Originally posted by mightydub
Get the Jasper circle jig - couldn't be easier to use, pretty much foolproof. No adjustments to slip.
Ditto. You might need the smaller one to get to 3" dia (I think the big one only goes to 4 1/4"). But it does go in 1/16" increments.
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Old 8th April 2008, 07:56 AM   #5
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What diameter and type was your router bit? How powerful is your router? I don't think you need a new jig, just practice with using the one you have. But you may have trashed your bit.
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Old 8th April 2008, 08:45 AM   #6
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Yeah - don't try and do a 1.5" cut in one pass. Do this in several passes slowly increasing the depth each time.

The only gotcha I've found with the Jasper jig is sometimes the pilot (centre) pin can drop through the hole (with enough vibration or movement) then your router wanders freely. The answer? Use some blu-tak on the reverse side to hold the pin against the MDF or whatever so it doesn't drop through.

Cheers,
David.
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Old 8th April 2008, 09:02 AM   #7
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Yup, I learned that way too - ruining a $40 piece of clear pine in the process

1/4" per pass is about right. Though I'm far more experienced now, even 3/8" per pass is really pushing it I find (tearout, not smoke the enemy there).

I use a scrollsaw for the big holes, then router the rebates with a homebrew jig that keeps the hole a circle and not some drunken ellipse

Glad your bit didn't blow apart and injure you

Practise makes perfect!

Cheers!



PS: In the hardware store, you'll usually be given the choice of a $10 router bit and a $45 router bit. Get the $45 one... you won't regret it! BIG difference in cut smoothness and performance.
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Old 8th April 2008, 01:17 PM   #8
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With a good bit cutting a hole through a 3/4" board in one pass should be no problem.

Whatever you do using power tools it's probably a bad idea if you have to apply much force with your own hands.

If Zaph recommends the Sears jig over the Jasper jig, he's probably tried both and unless you other guys have tried both maybe you shouldn't be telling him to get the Jasper Jig instead?

I like to use my 1/4" (mounted on a 1/2 shaft) straight bit to cut holes.

If you push hard when you cut you're going to make a lot of heat and prob. dull the bit faster, I've never tried cutting 1 1/2" in one pass, but with a good bit and a good router, I'd had no trouble cutting 3/4" birch plywood sometimes and 1/2" many times. Not sure about hardwoods though, I've used roundover bits on oak that went smooth and easy.

The bits I've got now are either Freud from Amazon.com or "Katana" brand from here: http://www.mlcswoodworking.com/shops...es/kathome.htm I'm sure the regular carbide bits from MLCS are fine too.

edit: oh, and I like my Hitachi M12V router I got for $150 ( ) at Amazon.com, unfortuanately, the price seems to have gone up to $280? It's green like the Hulk.
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Old 8th April 2008, 03:44 PM   #9
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To answer some questions, the router is 1/4". I think it's a 2 hp router, although I can't confirm that right now because I am still sitting around in my PJ's with my kid and it's cold out in my shop. The bit was a $16 Freud. I think my answer is gonna be taking multiple passes. I'll just make that the back of the sub, slap another board over that side, and mount the amp there instead. Then I'm sure I will proceed to ruin the other side somehow so I can start from scratch.
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Old 8th April 2008, 04:06 PM   #10
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Quote:
Originally posted by critofur
With a good bit cutting a hole through a 3/4" board in one pass should be no problem.


Truly a dangerous thing to do is attempt to cut through 3/4" material in one pass - overheating and the bit "chattering" in the cut are a poor way to do things. When cutting the hole with a router, use multiple passes (takes longer, but saves the expensive bit from getting ruined) and DON'T cut all of the way through. Leave 1/16" so that the centre of the hole doesn't break free and router goes crazy, injury is possible.

I use the router to cut the driver recess (rebate) only and use a jigsaw with a good SHARP blade to cut the hole.
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