How to slightly enlarge a bench dog hole

[scritch]

I made a workbench from some gluelams I got for free. It is quite substantial, being about 5 inches thick; very solid. I drilled some bench dog holes in it, and then I bought a holdfast.

Unfortunately, even though the holdfast was described as 3/4" diameter, it's really a bit larger, and I need to enlarge the dog holes by about

1/8". I saw one technique where you grind the shoulders of a spade bit at 60 degrees and proceed carefully down the holes to enlarge them. Does anyone have better ideas?

Also, I initially drilled too many holes. Any thoughts on plugging them? I might just glue in some dowels, but someone might have a more elegant idea.

Thanks,

scritch

[dpb]

On 10/12/2013 11:27 AM, scritch wrote: ...

I'd use a twist drill (carefully) -- it'll follow the existing holes more readily than the spade bit will.

Or, the really clean way would be to glue in a waste dowel and redrill as wanted w/ a Forstner.

Use a dowel for the bulk but cut some matching grain plugs 1/4" thick or so to mate up with the surface if want the appearances...

[WW]

I made a workbench from some gluelams I got for free. It is quite substantial, being about 5 inches thick; very solid. I drilled some bench dog holes in it, and then I bought a holdfast.

Unfortunately, even though the holdfast was described as 3/4" diameter, it's really a bit larger, and I need to enlarge the dog holes by about

1/8". I saw one technique where you grind the shoulders of a spade bit at 60 degrees and proceed carefully down the holes to enlarge them. Does anyone have better ideas?

Also, I initially drilled too many holes. Any thoughts on plugging them? I might just glue in some dowels, but someone might have a more elegant idea.

Thanks,

scritch

I would plug the holes with a dowel and then redrill with the proper sized fostner bit WW

[Gordon Shumway]

I'd use a twist bit and take it slow like dpb suggested. Or if you want to use a Forstner bit drill the desired hole size in a piece of scrap and then clamp it to your bench to be the guide for the Forstner bit to get it started. After you get deep enough you will no longer need the guide and it can be discarded.

This is an easy fix! Go to Harbor Freight and get one of their recently inventoried "Negative Kerf" drill bits. They're fantastic!! :-)

[woodchucker]

Return the holdfast, buy one from gramercy. I have 2 and love them.

[none]

On Sat, 12 Oct 2013 09:27:38 -0700, scritch

You might use an "Oops" arbor with two hole saws.. Lee Valley Tools sells them. I'm not sure that a 1/8" difference is enough to use smaller to larger hole saws, but you could visit an LV store and find out.

[dadiOH]

No idea if it is better but if you don't want to enlarge the holes, shrink the holdfast. You could take it to a machine shop or if you have something you can chuck it in - lathe, drill press, etc. - you could do it yourself with a stone.

Personally, I'd send it back. If they say 3/4 I expect 3/4.

You could get some epoxy, thicken it with talc (so it will be white/grey and opaque) and swirl in different colors. Personally, I'd just use the dowels :)

[Michael]

I would use the drill press to drill the proper sized holes in a substantial piece of hardwood. Then I'd clamp that hardwood to the proper position above the old holes and use it as a guide to enlarge the holes.

Mike

[Lew Hodgett]

--------------------------------------------------------- Return the defective dog(s) and make your own,

Start with 3/4" x 3/4" x 8" maple or white oak piece.

Setup router table with a 3/8" round over bit and fence with stops.

Machine a "dogbone" with 3/4" round in center and 3/4" x 3/4" x 1" ends.

Cross cut "dogbone" into two (2) equal pieces that become your bench dogs.

Lew

[BenignBodger]

If the holes are the correct size and the holdfast is too big then you should be grinding away at the holdfast to make it the correct size (or return it for one that is correctly sized). Other tools you might acquire in the future will want the dog holes to be the correct size and there is no way you are going to shrink them retroactively.

[woodchucker]

Excellent point.

I use dogs from veritas and holdfasts from Garmercy... all fit the same hole.

[lektric dan]

[Puckdropper]

scritch wrote in news:l3bt9l$o1g$ [e-mail]:

*snip*

If they're not in the way or you're only bothered by the look, I'd consider leaving them. If you add a vise to your bench, especially one without a quick adjust, more holes is a good thing.

Puckdropper

[krw]

That's what I would do, even with a twist drill. The hole in the "guide" scrap can be drilled at the same time. I'd probably use hardboard for the guide.

Should have used a portable hole.

[scritch]

Best idea yet! I ordered up two, too. Then, in a flash of inspiration, I turned a bunch of tapered plugs which I pounded into the holes I don't think I need. They will make the top smoother and can be tapped out from below should I need a new hole.

[Jim Weisgram]

I made my dog holes with a router and bearing guided router bit. They ended up perfectly square to the table. You could enlarge an existing hole by drilling an enlarged hole in a scrap piece and clamp that scrap over the existing hole, then enlarge with the router. Once the hole is started, you can go deeper in stages if the router bit is not long enough.