Seneca Imperial Depth Gauge not centered on plywood

[demerson3814]

Hello,
  I purchased the Seneca Woodworking Imperial Depth gauge for my DF500 and I'm not able to get centered mortises.  On both 1/2 and 3/4 plywood it is consistently off center, which defeats the purpose of it for me.  For 3/4 it is consistently off ~2 mms with the 5mm bit which make a big difference on such narrow stock. 
  I'm not getting great support from the manufacturer - very slow responses and at this point I'm outside the return period from the place I bought it from.
  Is anyone else experiencing this issue?  My options are to not use it (current) or try to get a replacement unit from SW.  Before going through the hassle of a replacement, I'd like to make sure others have had success with this unit on a newer (

 

[Xoncention]

For 3/4 it is consistently off ~2 mms with the 5mm bit which make a big difference on such narrow stock.

If you remove the Seneca and use the Festool original gauge with the same 5mm cutter, do you get the same 2mm offset?  Also remember that plywood is not what you think.  3/4" is nominal 18mm, not 19mm - this is where you may be getting your error - just a guess.  Try milling a piece of stock the exact dimension as your Seneca gauge and see if you still get this 2mm difference.

 

[Paul G]

The goal isn't to get perfectly centered mortises in plywood edges but instead flush joining when referencing the same faces or outside corner of pieces when cutting. All plywood is metric and varies. I've had expensive baltic birch sheets not even be the same thickness from one end to the other. Plywood is the wild west.

Over the last few years, I've never used the domino's own fence settings. The Seneca plate has done all the work I've needed, hassle free.

I agree with your assessment, the problem though is Senecas website says you get a centered mortise.
http://www.senecawoodworking.com/products/imperial-thickness-gauge-df500

"The Seneca Woodworking Imperial Thickness Gauge for the Domino DF500 allows you to quickly and effortlessly adjust the Domino fence offset to center your mortise on a variety of imperial material thicknesses"

It's an approximate center, but certainly can't expect it to be truly centered in spite of their unrealistic statement.

 

[Brice Burrell]

I agree with your assessment, the problem though is Senecas website says you get a centered mortise.
http://www.senecawoodworking.com/products/imperial-thickness-gauge-df500

"The Seneca Woodworking Imperial Thickness Gauge for the Domino DF500 allows you to quickly and effortlessly adjust the Domino fence offset to center your mortise on a variety of imperial material thicknesses"

It's an approximate center, but certainly can't expect it to be truly centered in spite of their unrealistic statement.

The claim is centered in imperial sized material, plywood is in metric, in most cases.

 

[Paul G]

I agree with your assessment, the problem though is Senecas website says you get a centered mortise.
http://www.senecawoodworking.com/products/imperial-thickness-gauge-df500

"The Seneca Woodworking Imperial Thickness Gauge for the Domino DF500 allows you to quickly and effortlessly adjust the Domino fence offset to center your mortise on a variety of imperial material thicknesses"

It's an approximate center, but certainly can't expect it to be truly centered in spite of their unrealistic statement.

The claim is centered in imperial sized material, plywood is in metric, in most cases.

If you read further down their page...

"The Imperial Thickness Gauge is CNC machined from Delrin material and designed to center on 1/2", 5/8", 3/4", 7/8", 1", and 1-1/8" nominal ply thicknesses."

Seneca well knows the sizes are nominal, and without knowing the actual thickness there is no way to truly center the mortise, and the centering is nominal as well.

That being said, I have a hard time thinking they would be off a few mm. I don't have this particular attachment but my Seneca domiplate does better than that

 

[Nat X]

If you take that same piece of wood and that same tool to Arizona you'll get one result, and if you take them to Houston you'll get another. There's no way anyone can guarantee absolutely perfect centering with a block of plastic, no matter how expensive it might be.

 

[Michael Kellough]

The Seneca plate will place the mortise a consistent distance from the reference edge of the material no matter what material you use or when you use it, except for dimensional changes of the material due to moisture content fluctuations.

The mortise will be near the center of nominal 3/4" or 1/2" plywood but as explained above it may never be exactly centered. It's not a fault of the product IMO but you could say it's a fault of the product description if you were misled.

 

[Klemm]

Right on, Michael.
I wasted  some time for the same reason when I first started using the DOMINO and I bet  quite a few purchasers do before they realize exact center is irrelevant - just consistency on mating pieces. DOMIPLATE does that but the resulting upside-down holding of the tool is a step backwards in user friendliness IMO.
Hans