# Proper bit for plunge cutting?



## ekesz13 (Jan 8, 2009)

Hi all, I am new to routing. Just got my first router and about to make some cuts in MDF for a speaker. I made a jig out of plexi and am ready to get started, then I wondered what bit I should use. My experience is in the machine shop, where you had to use the proper End Mill to plunge cut then traverse the piece. Using the wrong end mill that didn't have cutting flutes all the way to the centerline would result in a "post" of material sticking up and a lot of heat and noise. I am in a similar situation here, I will be plunging into 3/4" MDF (I am assuming the proper practice is just like in machining, take a 1/4" or so pass at a time in this instance). The cuts will not be visible, but I want to do them correctly. I have a starter kit of bits that don't seem to have anything I would think was a proper plunge bit. I want to do make the same type cut you see in the thumbnail below. What bit can I use? My router is 1/4" shank, and I would like to buy a bit locally to get this job done this weekend. Thanks in advance for your time!


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## bobj3 (Jan 17, 2006)

Hi ekesz13

Most router bits are not made to plunge,,but because you want one by this weekend I would suggest you pickup a 1/4" Spiral bit that you can get in town I'm sure.. ( HD/Lowes ) 

Spiral Upcut and Downcut Router Bits
Downcut spirals help hold the material in place while using handheld routers
http://www.mlcswoodworking.com/shop...rthtml/pages/bt_solid.html#spiral_down_anchor

Plunge Cutting Straight Router Bits

http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_plung.html


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ekesz13 said:


> Hi all, I am new to routing. Just got my first router and about to make some cuts in MDF for a speaker. I made a jig out of plexi and am ready to get started, then I wondered what bit I should use. My experience is in the machine shop, where you had to use the proper End Mill to plunge cut then traverse the piece. Using the wrong end mill that didn't have cutting flutes all the way to the centerline would result in a "post" of material sticking up and a lot of heat and noise. I am in a similar situation here, I will be plunging into 3/4" MDF (I am assuming the proper practice is just like in machining, take a 1/4" or so pass at a time in this instance). The cuts will not be visible, but I want to do them correctly. I have a starter kit of bits that don't seem to have anything I would think was a proper plunge bit. I want to do make the same type cut you see in the thumbnail below. What bit can I use? My router is 1/4" shank, and I would like to buy a bit locally to get this job done this weekend. Thanks in advance for your time!


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## ekesz13 (Jan 8, 2009)

Bob, thanks for the reply. Am I approaching this the correct way? Is there another approach, such as drilling a hole tangent to where I want the diameter of my cut out to be, thus allowing a bit to be inserted all the way through the 3/4" MDF. Then all it has to do is side cut as I rotate the router. Is this a better approach? Or should I stick with the 1/4" spiral cut, then plunge down and rotate around the work piece?


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## bobj3 (Jan 17, 2006)

HI ekesz13

"should I stick with the 1/4" spiral cut" yes,, you want a nice clean hole you don't want to do any sanding if you can help it... it will take a pass or two but the bit will do all the work for you..like they say it's easy to take it out but real hard to put it back in place... I would also suggest you cut a ring out for the inside of the box to help support the speakers and just a bit more meat for the screws that hold the speaker down in place..  you know how MDF is.. 

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ekesz13 said:


> Bob, thanks for the reply. Am I approaching this the correct way? Is there another approach, such as drilling a hole tangent to where I want the diameter of my cut out to be, thus allowing a bit to be inserted all the way through the 3/4" MDF. Then all it has to do is side cut as I rotate the router. Is this a better approach? Or should I stick with the 1/4" spiral cut, then plunge down and rotate around the work piece?


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## ekesz13 (Jan 8, 2009)

Bob, thanks again for the reply. I just went over to Lowe's and found a 1/4" x 1" Bosch upspiral straight bit for $19. Sounds like it will do the trick. Probably could have had a better quality one for the same price elsewhere online, but I wanted to tackle this tomorrow.

I agree with you on the backer plate, already have it incorporated into the design. This is a 10", 14 lb subwoofer for my wife's truck, so I wanted to give it 1.5" of support (double layer of the 3/4" MDF).

Thanks for all the help so far, this forum has a ton of great info and what seems like a great bunch of helpful folks. I am excited to start learning the ropes.


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## bobj3 (Jan 17, 2006)

You're Welcome ekesz13

My son is a shop mrg.at Car-Toys and he makes many,many speakers boxes and some of it rubs off on me...the last one was for a car that had all the doors filled up with cement and that had 18 batteries in the trunk, about 10 ton car with boom boom speakers .. hahahahahahaha LOL that my neighbors love to hear,,at 10:00 PM hahahahahaha ...want to move in next door hahahahah........



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ekesz13 said:


> Bob, thanks again for the reply. I just went over to Lowe's and found a 1/4" x 1" Bosch upspiral straight bit for $19. Sounds like it will do the trick. Probably could have had a better quality one for the same price elsewhere online, but I wanted to tackle this tomorrow.
> 
> I agree with you on the backer plate, already have it incorporated into the design. This is a 10", 14 lb subwoofer for my wife's truck, so I wanted to give it 1.5" of support (double layer of the 3/4" MDF).
> 
> Thanks for all the help so far, this forum has a ton of great info and what seems like a great bunch of helpful folks. I am excited to start learning the ropes.


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## dovetail_65 (Jan 22, 2008)

You have to see the stereo my new beater.

My son purchased the car new in 2001. A Monte Carlo SS. He had a ridiculous stereo that he just kept in the car when he gave it to me. 

Its outrages, 1800 watts per channel and a separate sub woofer amp with twin 12" subs in the trunk. The radio has a display that plays little skate board videos. It is so over the top! 

When I pick up the kids from the bus stop everyone is looking at the cool dad with the boom boom stereo!

It shakes so much it blew out his rear window out of its tracks twice and now I have no rear defog at all, it keeps shaking off. At least the window is on place.


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## bobj3 (Jan 17, 2006)

HI Nick

SOunds like my old 80 Ford truck 


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nickao65 said:


> You have to see the stereo my new beater.
> 
> My son purchased the car new in 2001. A Monte Carlo SS. He had a ridiculous stereo that he just kept in the car when he gave it to me.
> 
> ...


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## dovetail_65 (Jan 22, 2008)

Back in the 80's I had what was called an ADS power plate amp. Boy 80 watts per channel was all you needed becasue it was a true 80 watts that was usable. I see them now selling for more than they were new. 

I think these new wattage numbers are not a true representation of the actual power at clean sound levels, becasue that ADS could make you deaf before it ever gave a hint of noise in the sound.


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## bobj3 (Jan 17, 2006)

HI Nick

WHAT ? ,I say that a lot of the time in the truck   my son reworked the radio system ,, WHAT ? HAHAHAHA



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nickao65 said:


> Back in the 80's I had what was called an ADS power plate amp. Boy 80 watts per channel was all you needed becasue it was a true 80 watts that was usable. I see them now selling for more than they were new.
> 
> I think these new wattage numbers are not a true representation of the actual power at clean sound levels, becasue that ADS could make you deaf before it ever gave a hint of noise in the sound.


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## dovetail_65 (Jan 22, 2008)

Wear hearing protection!!!


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## levon (Sep 14, 2008)

bobj,

thats a great lookin truck, wish i had it now!


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## bobj3 (Jan 17, 2006)

Thanks levon

It's 29 years old but still running strong  I put a 460 eng. in it, but I wanted to pull some trailers but other than that it's stock...plus it has steel bumpers  

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levon said:


> bobj,
> 
> thats a great lookin truck, wish i had it now!


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## levon (Sep 14, 2008)

bobj, you still own this truck?


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## bobj3 (Jan 17, 2006)

Hi levon

yep, still in front of the garage door 

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levon said:


> bobj, you still own this truck?


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## Skyglider (Nov 2, 2008)

Bobj,

Did you paint that truck?


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## bobj3 (Jan 17, 2006)

HI Skyglider

Yep,, about 15 years ago, it was red and gray from the fac. it's about time to repaint it, some of the clear coat is coming off in spots,,the Sun will do that, for the pass year or so it's been a outside truck and the weather started to get to the paint job... 

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Skyglider said:


> Bobj,
> 
> Did you paint that truck?


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## harrysin (Jan 15, 2007)

1.8Kw per channel, that would draw as much as a starter motor! at least 300 amps, even with the biggest capacitors available across the batteries, me thinks there would be problems. With power like that, once moving, the engine could be stopped and the air pressure from the drivers used to push the car along!


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## dovetail_65 (Jan 22, 2008)

Yeah you need a separate battery, a beefed up alternator and a huge special capacitor designed for these stereos and sold with the big amps that he has installed under the dash somewhere(or maybe he meant under what he calls the dash in the trunk). In the trunk there is a separate head unit with CD and cassette that can be operated from the the trunk when it is open.

This stereo is nothing these days and my sons was nowhere near the most powerful as many of his friends do this as a hobby and try to out do each other,.

I can literally feel like a vacuum type pressure if it is turned up a little and a window is not cracked open.


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## bobj3 (Jan 17, 2006)

Hi Harry

They now use cable that's as big as your thumb for the power line for the amps...
many have 2 to 4 batteries in the trunk just for power for the amps.most are the yellow or red top batteries, that cost about 200.oo bucks each.. 

Most go just a bit nuts with the new stuff... my son showed me one that the guy put in $18,000.oo just for the sound..and he said that's on the low ends sometimes..


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harrysin said:


> 1.8Kw per channel, that would draw as much as a starter motor! at least 300 amps, even with the biggest capacitors available across the batteries, me thinks there would be problems. With power like that, once moving, the engine could be stopped and the air pressure from the drivers used to push the car along!


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## dovetail_65 (Jan 22, 2008)

Yes my son used "Monster" cable brand I believe.


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## Skyglider (Nov 2, 2008)

bobj3 said:


> HI Skyglider
> 
> Yep,, about 15 years ago, it was red and gray from the fac. it's about time to repaint it, some of the clear coat is coming off in spots,,the Sun will do that, for the pass year or so it's been a outside truck and the weather started to get to the paint job...
> 
> ===


Getting to know you, I figured you painted it.... 
Nice job!


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