# Mortising Jig Adventure



## cbsjoez1935 (Mar 14, 2007)

Hi Everyone,

Well I do not know if this falls into a dumb and dumber situation, but here goes. I made an 8" square piece of phenolic to fit my Hitachi MV12 and put in a center hole to accomodate PC style guides. So far so good. I bought a set of bearings from OP and mounted them on the corners after first measuring the distance on a scribed line from corner to corner that centered itself across the opening. I drilled holes for the bearing bolts that were equal distance from the centering rod coming through the 1/4" guide. I adjusted and tightened the plate screws to the router. Now I was ready to go a make some mortises. I fashioned a jig, similar to the one from TRW and made my first morises. Hooray, except they were not exactly centered so that the tenon fit flush on the sides. I may be nitpicking here, but I measured the ofset to be 1/32". I solved the problem by reversing the wood in the jig and remortising the mortise. Should I be overly concerened about this or did I do something wrong. Bob R never seemed to have this problem on the show.

Joe Z.


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## bobj3 (Jan 17, 2006)

Hi Joe

It should be dead on,,just drill a bigger hole and use it to adjust it..

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cbsjoez1935 said:


> Hi Everyone,
> 
> Well I do not know if this falls into a dumb and dumber situation, but here goes. I made an 8" square piece of phenolic to fit my Hitachi MV12 and put in a center hole to accomodate PC style guides. So far so good. I bought a set of bearings from OP and mounted them on the corners after first measuring the distance on a scribed line from corner to corner that centered itself across the opening. I drilled holes for the bearing bolts that were equal distance from the centering rod coming through the 1/4" guide. I adjusted and tightened the plate screws to the router. Now I was ready to go a make some mortises. I fashioned a jig, similar to the one from TRW and made my first morises. Hooray, except they were not exactly centered so that the tenon fit flush on the sides. I may be nitpicking here, but I measured the ofset to be 1/32". I solved the problem by reversing the wood in the jig and remortising the mortise. Should I be overly concerened about this or did I do something wrong. Bob R never seemed to have this problem on the show.
> 
> Joe Z.


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## BigJimAK (Mar 13, 2009)

Joe,

The bushing needs to be centered to the collet, not the guide plate. What you need is a router base centering pin. They sell for about $8. One source is Router Accessories

Its the 6th item down on that page.


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## cbsjoez1935 (Mar 14, 2007)

BobJ
Thanks for the reply. What hole do I need to make bigger and then adjust (Bearing Screw Hole)? Does this mean off of the axis??
Big Jim
I may have misstated how I did it, but I did use a 1/4" router base centering pin in the collet and then used a 1/4" ID guide in the plate to get everything centered.


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## bobj3 (Jan 17, 2006)

Hi Joe

The ones on the corners of the plate,just use some washers ,easy way chuck up a 1/8" bit or a router with a point on it,,and then adjust it for dead center of the line,,

http://www.routerforums.com/jigs-fixtures/2641-mortise-tenon-jig-plunge-router.html

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cbsjoez1935 said:


> BobJ
> Thanks for the reply. What hole do I need to make bigger and then adjust (Bearing Screw Hole)? Does this mean off of the axis??
> Big Jim
> I may have misstated how I did it, but I did use a 1/4" router base centering pin in the collet and then used a 1/4" ID guide in the plate to get everything centered.


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## cbsjoez1935 (Mar 14, 2007)

Bob,

Thanks again. That looks like it will solve my problem. I'm glad I asked.

Joe Z.


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## Hamlin (Dec 25, 2005)

Joe,

If your scribe line is still visible, use a string line to make sure that everything is truly aligned. You could raise the bit to where it's just seen at the end of the guide to give you a center point from the bit. It should be a simple straight line. 

Also make sure the distance from each bearing to the bit is the same. The actual distance doesn't really matter but, both have to be equal.


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## laxknut (Oct 17, 2008)

*centering*

If you don't have a centering plug/guide, you can align your base with a pre-existing hole to the router by chucking in a forsner bit as long as the bit dia. matches baseplate hole dia. You can even use a matching regular 2 fluted dado bit by slightly rotating it in the hole.
Hope that makes sense.


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## bobj3 (Jan 17, 2006)

Hi Bill

Good tip but getting the plate on center for the setup is not the point, it's a simple geometry thing that must be fixed..for the jig to work right every time it's use..

But here's a simple jig that can be made in the shop to line up just about any router that can take on the template guides.and some that don't use the guides with a bigger plastic ring plate.. 

see below

Router Forums - View Single Post - Can't Find Craftsman Router Base Plate


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laxknut said:


> If you don't have a centering plug/guide, you can align your base with a pre-existing hole to the router by chucking in a forsner bit as long as the bit dia. matches baseplate hole dia. You can even use a matching regular 2 fluted dado bit by slightly rotating it in the hole.
> Hope that makes sense.


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