DF500 -- Domino Deepening Jig (8mm & 10mm)

[ChuckM]

In one previous table project, I have used a drill bit to deepen some 10mm mortises (cut with a DF500) so I could use the 10mm x 24mmx 80mm dominoes in 6 joinery locations. I wanted a proper jig to do the drilling job if in the future, the need arises again. Here is what I came up with: one for deepening 8mm dominoes; one, 10mm.

10mm drill bushings, as it turned out, aren't easy to find (drill guides and steel tubes that are sold as 10mm I.D. were not really 10mm in diameter! ). (http://festoolownersgroup.com/other-tools-accessories/source-for-10mm-dia-drill-bushing/msg579926/#msg579926)

After trying out a few supplies, I settled with this:http://www.leevalley.com/en/wood/page.aspx?p=32246&cat=1,180,42311,42335 (link no longer valid probably due to product not carried anymore)

Of course, if your work requires the frequent use of both small and short dominoes, and large and long dominoes, acquire a DF700 in addition to the DF500.

 

[ChuckM]

Almost two years later after I made the deepening jigs, I finally got to use the 8mm jig for my latest chair project, and it WORKED, making six mortises twice deeper.

 

[Svar]

Instead of bushing use sealed ball bearings. Stack them to achieve desired height.
They are hard and much more accurate than bushings, not to mention easy to find in variety of sizes. But most importantly they rotate during use, decreasing friction and wear.
Another benefit of rotation is possibility for much tighter fit. Stationary bushing has to be oversized to avoid jamming, which allows for some bit wobble.

 

[ChuckM]

Ball bearings do sound a better alternative for long-term use, especially if the jig is used often. The guide bushings do have the advantage of easy and quick implementation.

If anything, I do need to get a better 8mm bit in place of the utility brad point bit.

If someone makes a deepening jig like a self-centering/self clamping drill guide with interchangeable bushings (e.g. 6mm, 8mm and 10mm), I'd consider buying it.