# Modifying an Incra Miter Gauge to Fit an Oversized Miter Slot



## RickKr (Dec 30, 2018)

I have a Bosch router table with a 12mm, but the slot width actually measures 0.786". I bought an Incra 1000SE Miter Gauge a couple months ago and have been foiled at using it because of the oversized slot in my table. The Incra miter bar has expansion discs to adjust to fit variations in the standard 3/4" wide miter slot, but the extent of expansion was to just 0.760". I didn't like the slop of the miter bar and felt the accuracy of the 1000SE would be compromised. 

It took me a while to settle on "how" to compensate for the over wide slot. At first, I thought of making larger expansion discs and milling out the pockets to accommodate them. Too much work and I couldn't be sure it would be enough. Then I thought of adding a shim to the slot to narrow it so the stock Incra bar/discs could be used. I wasn't sure just how to add such a thin shim, too thin to screw down and I didn't like the idea of using adhesives. 

I settled on drilling and tapping horizontal 1/4-20 holes along the bar and inserting nylon 1/4-20 socket head set screws on both sides. With a hex key, it is easy to adjust the set screws for the additional width that was needed and being nylon, provide some easy sliding. I crimped the threads a bit to make them a bit snug so they wouldn't loose position as easily. 









It took some fiddling to figure out the easiest and fasted way to adjust the set screw heights, as I wanted them to be the same all along each side, there are six on each side. Once it was adjusted, there was no perceptible sideways movement but it slide along the slot very easily. Part of my design criteria was that it should be easy to adjust and change because I may want to use it on my bandsaw and disk sander and they have more standard 3/4" slots. I haven't tried switching it yet, but set screws on both sides of the bar, I am hoping one side can be set to work at the 3/4" width (with the other side fully recessed) and to other side for the Bosch table with the wider slot. I could not figure out how to do that with larger expansion discs. 









I used the Incra 1000SE Miter Gauge for cleaning up slots in brackets for my daughter's rug loom. It worked beautifully. 

Rick


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## Stick486 (Jan 4, 2013)

layered *UHMW tape* to the side of the miter rail...


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## tulowd (Jan 24, 2019)

Nice; I have the same, but reversed problem; bought an Incra V27 miter gage and it won't fit into my ancient Craftsman 10" contractor table saw, cause the slots are too narrow and I never thought to measure this first, duh!!

Since the saw is packed away in the basement, I have some time to think about how to fix it. 

1) Buy a real saw, to go with my new to me Excalibur high end fence
2) Mill out the table slots, leaving the side closest to the saw true and original
3) Make a new mitre slide by cutting down a standard one - already bought one so that may be the best option.

Thoughts from the experts?

Thx

Paul


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## Stick486 (Jan 4, 2013)

new fitted rail...


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## Nickp (Dec 4, 2012)

stick486 said:


> new fitted rail...


+1...


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## RickKr (Dec 30, 2018)

Stick486 said:


> layered *UHMW tape* to the side of the miter rail...


Thanks. I did not know about this material. Mods to this one are done and I like that it is transportable between machines with the set screws. If I put that on the bar, the miter gauge would only be usable on the router table. I'd be more inclined to put it on one or both sides of the miter slot on the router table so the miter gauge could be used on all three machines. 

But, I have ordered a roll of it because it clearly will be a useful material. 

Curious though, the nominal thickness listed is 1/32" but in the product item line, it is shown as 0.025" thick. That makes a difference. The thickness that needs to be made up in the case of my router table is 0.050". If the tape is 1/32", I could only get one layer on, which would still leave some slop. If it is 0.025", I might be able to get two layers (one on each side). If that were too tight, I would file out some clearance in the table slop. I think if might be easy to do that, as there is paint or powder coat covering both sides and the bottom. 

Rick


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## RickKr (Dec 30, 2018)

tulowd said:


> ...snip...
> 3) Make a new mitre slide by cutting down a standard one - already bought one so that may be the best option.
> 
> Thoughts from the experts?
> ...


New miter bar sized to fit the table slot. You could make it from any bit of bar stock that fits your table slot (or modified it to fit), as there are only four threaded holes that you'd need to put in if you didn't need their expansion discs, which hopefully, you wouldn't because you would size the bar to fit the slot. 

Rick


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## ic3ss (Mar 10, 2011)

Hi Rick, nice fix but I have an easier way to solve this problem.

The problem is: Incra made the milled recess exactly the same diameter as the expansion discs, and when you put in the countersunk screw that is supposed to push the disc apart, it can't because one half of the disc is locked in by the milled recess and can't move outward. This makes is to the screw also can't push out the other side to tighten your miter slot fit. What is needed is more room within the milled recess.

First make sure the expansion discs are rotated to one side of the milled opening as the directions say.
Then make a mark on the disc at the other end of the opening. 
Then remove the expansion disc and use a wheel grinder to remove just a sliver of plastic, starting from the split and continue the long way around to where you made the mark. This should be a little less than 3/4 of the circumference of the disc. Only remove a very small amount. 

This gives some room for the disc to move apart in both directions away from the screw when the screw is tightened. 

See below picture. Note how far the split is now. No milling or drilling any metal required, only grinding on replaceable nylon discs.


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## jw2170 (Jan 24, 2008)

G'day @ic3ss , welcome to the forum.
This is a very old post, but your answer may help someone else in the future,
Thanks for posting..


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## old55 (Aug 11, 2013)

Welcome to the forum @ic3ss


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## WurliTzerwilly (Jun 9, 2013)

tulowd said:


> Nice; I have the same, but reversed problem; bought an Incra V27 miter gage and it won't fit into my ancient Craftsman 10" contractor table saw, cause the slots are too narrow and I never thought to measure this first, duh!!
> 
> Since the saw is packed away in the basement, I have some time to think about how to fix it.
> 
> ...


Mill (rout) out the miter slots and fit a 'standard' miter slot rail.


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## mgmine (Jan 16, 2012)

Why such an exact miter gauge on a router table? Besides keeping a piece of wood straight while routing the end of a board what else would it be used for?


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## WurliTzerwilly (Jun 9, 2013)

mgmine said:


> Why such an exact miter gauge on a router table? Besides keeping a piece of wood straight while routing the end of a board what else would it be used for?


Because an inexact miter gauge would introduce errors and whilst tolerances in wood are not as tight as (say) steel, no point in starting off with built-in errors.
Take a look at some Incra videos, which will show the many uses of a miter gauge on a router table. Dovetails spring to mind and there are many more.


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## mgmine (Jan 16, 2012)

alan_9685 said:


> Because an inexact miter gauge would introduce errors and whilst tolerances in wood are not as tight as (say) steel, no point in starting off with built-in errors.
> Take a look at some Incra videos, which will show the many uses of a miter gauge on a router table. Dovetails spring to mind and there are many more.


I looked and looked but couldn't find anything. There are plenty of examples of using the miter gauge to hold wood perpendicular to the fence but I'm still at a loss as to when you use a router to route angles.


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## WurliTzerwilly (Jun 9, 2013)

This guy talks about its uses and there are more that he doesn't mention.

Miter gauges

I make raised panels, but I use a jig rather than a miter gauge, simply because it's more convenient and permanently available - doesn't need setting up each time.


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