Newbie needs help with domino centering

[clogger]

I have 2 pieces  of 16mm piece of wood I want to  join together with a Domino.
I am using a 8mm bit and set the height gauge to 16.

After cutting the slot I could see the slot was not centered? the top of the slot was only 2mm from the top and  the bottom of the slot 8mm from the base.
What am I doing wrong?, or is it not possible to center a slot in 16mm wood?

 

[mouppe]

A very common error when first using the Domino is to rest the domino on the workbench by mistake. This will raise the height of the mortise even though you have set the height gauge. You need to ensure the wood is hanging off the table when plunging.

Richard.

 

[Alan m]

the fact that it is closer to the top says that it can be centered, if it was the other way round then the fence might not be able to lower enough. i would raise the fence height setting by 3 mm so that there is 6 mm top and bottom . this centering only needs to be rough as it wont matter

 

[clogger]

Thanks for the prompt replies.
When I get home into the garage I'll make sure the Domino isn't resting on the workbench and check the result. I'm an idiot not checking for that! [embarassed]

 

[mouppe]

I am sure that is what is causing the problem, and I know you know how I know that's what it is!

 

[Alan m]

I know you know how I know that's what it is!

try saying that a few times
is it tongue twister time [big grin]

 

[Rick Christopherson]

It is a common thought with new users that it is necessary to center the tenons in the material. It's not necessary in the first place. You should be registering the mortise height from the same surface on each piece, so it doesn't matter if they are centered. The other thing is that when you try to get them centered, it opens up the possibility for assembly errors by making it less obvious if you flip one of the boards over.

Another thing, although you didn't say what type of material you were using, I believe you are using too large of a tenon for 16mm thick workpieces. You would be better off using the 5 or 6 mm tenons.

Take a look at the Supplemental Manual.