Increasing the M12v’s throat opening with a surprise twist. PICS

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Blog entry by Gord Graff posted 10-01-2007 11:15 PM 2462 reads 1 time favorited 9 comments Add to Favorites Watch

Howdy All,

Recently a friend of mine complained to me that his Hitachi M12v didn’t have a large enough throat opening to accommodate the larger horizontal panel raising bits. It’s a simple process to cut the offending template bushing “ears” off but what if you wanted to use a template bushing after removing these “ears”, you’re out of luck.

I’ve come up with a very simple way to solve the problem of removing the template bushing ears by replacing them with a lexan sub base. So now you can remove the offending ears and still use a standard Porter Cable set of template bushings.

Rather than try to explain my remedy for this obstacle over the phone I decided to put it in picture form. I hope that it helps others who may have the same issues.

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It’s a simple process to remove the template bushing ears; I removed mine by simply cutting them off with a jig saw and a metal blade. Of course the base assembly was removed from the router first.

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One must be careful not to remove too much material in this area and compromise the structural integrity of the router base. Careful machining and sanding results in a nice clean opening.

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With the ears removed I can now concentrate on making a new base plate for the router that will hold the template bushing. By the way, I prefer to use the standard 1 3/8” Porter Cable type template bushing and the brass bushings seem to hold together a lot better than the regular steel ones.

My new base plate material is a piece of ¼” Lexan that was laying around the shop and is perfect for this, it wears well, easy to machine with woodworking tools and is almost bullet proof. The original base plate was removed from the router and clamped onto the new blank in order to accurately drill the mounting holes; care must be taken here when drilling these holes to assure a perfect fit to the router base.
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Once the holes are drilled, the footprint of the original base plate is traced onto the new blank to be cut out later. Best to do it now while it’s all clamped together. There is one more machining step to do before I can proceed, the blank is now flipped over and the holes that were just drilled are countersunk to accommodate the original base screws.

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With the blank now installed on the router the next step is to install a ¼” spiral bit into the router. I’ve chosen this size router bit because it matches the pilot drill bit in the mandrel of my hole saw set, more about that in a minute. The spiral bit is plunged through the Lexan and then the blank is removed from the router.

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The next step for me was to place the blank “bottom side” up on the drill press table. The bottom side is the surface with the countersunk screw holes facing up. The ¼” pilot bit in the mandrel of my hole saw is lined up perfectly with the ¼” hole that was plunged by the router and clamped securely to the drill press table. The size of the hole saw that is required to make the through hole in the blank is 1 3/16”. This is the size of hole that is required for my Porter Cable type template bushings.

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Once this through hole is drilled, the hole saw is removed from the drill press chuck and replaced with a 1 3/8” forstner bit. The 1 3/8” forstner bit will provide a very clean and accurate hole for the template bushing to fit into. Care must be taken to drill this hole to the right depth, I’m looking for the bushing to “just” sit shy of the surface of the Lexan.

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From start to finish attention to careful machining will yield this as a result. Take my word for it; the router bit is exactly centered in the opening.

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All in all, this is simply just one way of solving the problem of accommodating using large router bits in a router that doesn’t have a large factory opening and still being able to do template routing. The tools that were required were few and found in almost every woodworking shop. What you may not have doesn’t cost very much to procure. Hope this helps.

All the best

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-- Informing & Inspiring Today’s Woodworkers:

9 comments so far

View Grant Davis's profile

Grant Davis

770 posts in 3936 days

#1 posted 10-01-2007 11:21 PM

Once again, another awesome display of your genious.

-- Grant...."GO BUCKEYES"

View Thos. Angle's profile

Thos. Angle

4444 posts in 3990 days

#2 posted 10-02-2007 12:17 AM

These are just some of thebest instructions I’ve had . They are a lot clearer that the ones in magazines. Probably because they are not trying to sell anyting. This is what LumberJocks is all about. What took you so long to find us?

-- Thos. Angle, Jordan Valley, Oregon

View Zuki's profile


1404 posts in 4105 days

#3 posted 10-02-2007 12:27 AM

View Dano's profile


222 posts in 4059 days

#4 posted 10-02-2007 01:51 AM


Outstanding, I have that router in a bench dog table attached to my table saw. I want to enlarge the opening but was concerned about loosing the ability to use bushings. PROBLEM SOLVED! This weekend we remove the ears, thanks for the idea and process!

-- Dan in Central Oklahoma, Able to turn good wood into saw dust in the blink of an eye!

View Douglas Bordner's profile

Douglas Bordner

4024 posts in 4091 days

#5 posted 10-02-2007 02:02 AM

Didn’t even scratch up the Lexan. You are something else. Great work.

-- "Bordnerizing" perfectly good lumber for over a decade.

View mot's profile


4911 posts in 4064 days

#6 posted 10-02-2007 02:39 AM


-- You can discover more about a person in an hour of play than in a year of conversation. (Plato)

View twill57's profile


24 posts in 3920 days

#7 posted 10-02-2007 03:10 AM

Nice work on the base plate. I am curious, how did you get the ears off so cleanly?

-- Tom, Grove City, Ohio

View Karson's profile


35125 posts in 4428 days

#8 posted 10-02-2007 04:46 AM

Great job Gord. A clean modification and an accurate solution.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Southern Delaware soon moving to Virginia †

View David's profile


1969 posts in 4166 days

#9 posted 10-02-2007 04:46 AM

Gord -

Another great instruction! Thanks. You do awesome work . . . keep these coming.



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