# Bits /Cutters for Exact Dado Cuts



## sreilly (May 22, 2018)

Well now I see cutters for dados and am wondering if it is better to make single passes for width or smaller bits and multiple passes. I'm guessing that using other wood than ply would require either planning the wood to exact thickness to fit the cutter or use smaller bits and make the passses needed to fit the wood. Any ideas? Better way to start? 













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## Stick486 (Jan 4, 2013)

I like dual pass w/ a narrower bit than the finished dado or groove... no planing required usually...
makes for a cleaner cut...


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## woodknots (Mar 7, 2012)

Using an "exact fit" dado jig, I use a smaller bit and make two passes. As stick says, makes for a cleaner cut.

Check out @MT Stringer uploads/posts for an exact fit jig, but there are a number of similar jigs on youtube.


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## Cherryville Chuck (Sep 28, 2010)

Members are finding that plywood thicknesses are so varied these days that exact thickness bits don’t always work so many are resorting to the 2 pass method.


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## sunnybob (Apr 3, 2015)

Cherryville Chuck said:


> Members are finding that plywood thicknesses are so varied these days that exact thickness bits don’t always work so many are resorting to the 2 pass method.


 Its the dreaded metrification, creeping in by the back door. you'll be fine in another 20 years or so, once imperial has finally died out.


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## MEBCWD (Jan 14, 2012)

sunnybob said:


> Its the dreaded metrification, creeping in by the back door. you'll be fine in another 20 years or so, once imperial has finally died out.


Actually I think the sizing in todays plywood is a lack of standards, poor manufacturing processes and no quality control. About 6 months ago I saw a load of plywood that was 1/8" difference in thickness from one side to the other. They were waiting on a truck to pick it up and return it to the distributor. The overseas manufacturer's machinery in a new plant was out of wack and no quality control lead to this plywood being sent all the way to a US store before anyone even noticed.

I know I have found large voids in some of the overseas plywood just by running my hand over the surface so I have been buying US made plywood , cost a little more but I don't have to deal with the voids.


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## Stick486 (Jan 4, 2013)

MEBCWD said:


> 1... Actually I think the sizing in today's plywood is a lack of standards, poor manufacturing processes and no quality control.
> 2... The overseas manufacturer's machinery in a new plant was out of wack and no quality control lead to this plywood being sent all the way to a US store before anyone even noticed.
> 3... I know I have found large voids in some of the overseas plywood just by running my hand over the surface *so I have been buying US made plywood* , cost a little more but I don't have to deal with the voids.


1... whole heartily agree...
2... they don't care.. we, the consumer, are their QC..
3... as long as this junk satisfies the wallet buyers.. it will continue to be dumped on us... 
look how much FOD you can find in the plies of offshore plywood...
and we get their better junk if you can imagine that...
I like your support America stance... *KUDOS...*

refuse to buy it...
won't be long before things change... 
look what happened to a few companies here as of late because they PO'd the American consumer...
accept garbage and you'll get more garbage.... stink and all...
the next counter body that tells you *''Well that is all there is''* jack slap 'em and shop elsewhere... 
management will hear you loud and clear... money talks...

*FOD: Foreign Object Debris (FOD) is any article or substance, alien to a product or system, which could potentially cause damage....*
https://en.wikipedia.org/wiki/Foreign_object_damage


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## Herb Stoops (Aug 28, 2012)

Go Harbor Freight!!!

Herb


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## reuelt (Dec 29, 2008)

*Undersized router bits for nominal 1/4" and norminal 1/2"*

For the nominal 3/4" plywood (for shelves) it is feasible to do two passes using short 1/2" PATTERN BITS.

However for nominal 1/4" and nominal 1/2" plywood it is more feasible to use quality UNDERSIZED PLYWOOD DADO PLUNGE ROUTER BITS

e.g from AMANA

://www.toolstoday.com/undersized-plywood-dado-plunge-router-bits.html

CONDITION is you will need a PLUNGE ROUTER not a FIXED BASE ROUTER and a supplier of plywood with Standard dimensions.


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## reuelt (Dec 29, 2008)

*Cheap Chinese Undersized bits for DIY/handiman available*

For about $15 from ebay.


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## TwoSkies57 (Feb 23, 2009)

Finishing up a pantry closet w/1/2" ply panels. Used an undersized 15/32nd's ply bit. the fit was perfect. Getting that perfect fit in a single pass nowadays is a real crap shoot. 

AS a lil side note. The Rockler Louver jigs are great!


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## reuelt (Dec 29, 2008)

TwoSkies57 said:


> Finishing up a pantry closet w/1/2" ply panels. Used an undersized 15/32nd's ply bit. the fit was perfect. Getting that perfect fit in a single pass nowadays is a real crap shoot.
> 
> AS a lil side note. The Rockler Louver jigs are great!


If you are in mass production single pass is better than multipass (time is money).
So Send a plywood sample to e.g. Carbi-tools and make some undersized bits TO ORDER.

I know a Church member who used to grind down his router bits with a diamond wheel to fit the plywood available. He later used CNC routers instead.


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## Herb Stoops (Aug 28, 2012)

@reuelt
a PLUNGE ROUTER not a FIXED BASE ROUTER a

Why does it have to be a plunge router? I have done lots with fix based routers long before the plunge base was ever born.
Herb


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## Stick486 (Jan 4, 2013)

Herb Stoops said:


> @reuelt
> a PLUNGE ROUTER not a FIXED BASE ROUTER a
> 
> Why does it have to be a plunge router? I have done lots with fix based routers long before the plunge base was ever born.
> Herb


ditto...


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## woodknots (Mar 7, 2012)

Stick486 said:


> ditto...


ditto, ditto


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## reuelt (Dec 29, 2008)

Herb Stoops said:


> @reuelt
> a PLUNGE ROUTER not a FIXED BASE ROUTER a
> 
> Why does it have to be a plunge router? I have done lots with fix based routers long before the plunge base was ever born.
> Herb


Sorry, I was just quoting Amana - which make those bits and specified that they are for Plunge Base Routers since it is often more convenient to cut stopped DADOs with a plunge router than a fixed base router.

Personally, I have no problems with Fixed based router. My first router was a B&D fixed base and I bought and learned from the B&D book titled "Router Craft" by George Blake.

I think the reason why the Undersized DADO bits specifies Plunge Base Routers is because In the EU, DADO blades for the table saw are illegal and all table saws sold in Europe must have a riving knife - making dado cutting with the table saw (they call SAW BENCH) impossible.
What do they specify must be used for cutting DADOS? "The PLUNGE BASE ROUTER" - invented by ELU in Europe.

In USA, most people use their table saw with DADO BLADES (stacked or wobble) to cut DADOs. So the market of undersized router bits for Fixed Base Routers (mostly used in the USA) relatively smaller.


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