# Mitre slot : straight or T-slot?



## matt1710 (Sep 21, 2010)

Hello

I recently purchased an Incra V27 mitre - and now have to route a slot for it in the table. I have a few questions:

1. How close to the edge of the mounting plate, should I route the slot?

2. The mitre gauge can be installed in either a straight bottom 3/4" wide slot (3/8" deep), OR a 15/16" T-slot at the bottom. I imagine there are advantages/disadvantages to both. Would someone please educate me on these?

3. I guess I can just route a 3/4" wide channel in the table (laminate top, 2 x 18mm laminated MDF as substrate) - but assume the mitre gauge will run better in an aluminium mitre slot installed in the routed channel?

Matthew

PS - I intend to run jigs in the mitre slot as well - jigs that have a 3/4" machine bar for the slot. Does this preclude me having a mitre slot with a T-slot? 

PPS - have attached a diagram of my router table - this may help with advice re where to route the mitre slot.


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## CharleyL (Feb 28, 2009)

Matthew,

I prefer the T type miter slots. If you have one you can use either a standard miter gauge or a T type. The T part of the slots was added to provide some hold down capability as the miter gauges and fixtures that are intended to mate with it have washer(s) inserted in the bottom of the bar that ride in the T, and prevent the jig or miter gauge from lifting during the cut. It's more of a safety addition than it is a woodworking requirement.

To determine the correct miter slot location your jigs, sleds, and miter guides must clear your largest cutter bit. I always place it a bit farther than this, so there is about 1" of clearance between my largest sled and my largest cutter. I use backer boards to prevent chip-out and these can be set for zero clearance to the bit anyway. 

Charley


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## jschaben (Jun 21, 2009)

matt1710 said:


> Hello
> 
> I recently purchased an Incra V27 mitre - and now have to route a slot for it in the table. I have a few questions:
> 
> ...


Hi Matt - congratulations, the Incra is a nice mitre.
Most of the commercial fixtures and featherboards, etc, that require the use of a mitre track require the centerline of the track no more than 6" (150 mm) from the centerline of the bit. Since your plate is 210 mm wide, that says the centerline of the track would be ~ 25 - 30mm from the plate. Personally, I prefer to run them in an aluminum track and I'm not sure how effective the slot adjustments on your miter gauge will be in the MDF.


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## del schisler (Feb 2, 2006)

*router table*

i don't have and miter or T slot's on my router table. I have the router work shop table and i use these Oak Park table fences are made of polyethylene and are complete with a lexan bit guard. Available in two different sizes, 19" and 24". The jointer fence has an off-set of 1/16" and is available in two sizes 19" and 24". . I can do anything those other's can do with out all the miter's and T slots can do . Here is a link to all their item's i have lot's of them 

Oak Park Enterprises Ltd.: Catalogue


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## Cherryville Chuck (Sep 28, 2010)

For most mitre work I prefer using a sled that runs against the main fence, thus is guaranteed to be perpendicular. One operation I can think of that would make t-tracks handy is if you wanted to slot the ends of boards for stiles or frames you could lock a mitre fence down to the right of your slotting bit.


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## matt1710 (Sep 21, 2010)

Thanks for all the advice. As I already have the mitre gauge, I'm going to install it - I know that its inclusion in a RT is a subject of much debate, however I feel that it will eliminate one more thing that I need to keep an eye on, when guiding material into the bit : ie that the workpiece is perpendicular to the direction of travel. I've had a few instances of the sled or support block moving away from the fence as I've pushed it through - resulting in a non-perpecdicular cut. Probably bad technique, but that's what I've found.


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