Sjoberg bench dog holes sizing?

[JDuke]

I picked up a used sjoberg branded bench and 19mm or 3/4 dogs slip into the holes on the vices, but are to big for the holes in the table field.

Is this a common problem, a feature, or something I’m missing?

Thanks
Duke

[jteneyck]

I picked up a used sjoberg branded bench and 19mm or 3/4 dogs slip into the holes on the vices, but are to big for the holes in the table field.

Is this a common problem, a feature, or something I’m missing?

Thanks
Duke

Maybe the ones in the field are for a hold fast?  

John

[Admiral]

Weird. All my holes are 1" (whatever that is in metric) both in the benchtop, the vices or the side members. My bench is circa 2004 if that is any help.

[taxman]

Mine are all square. 

Been thinking of making a tight square fit with a 3/4" hole so I can use all the round bench toys. 

Have been hesitant to drill holes, but that is the correct answer.

[JDuke]

Any downside to opening them up to 3/4”
Are there any bench accessories that I’ll be unable to make work with that?

[alanealane]

Any downside to opening them up to 3/4”
Are there any bench accessories that I’ll be unable to make work with that?

Not that I can think of. Pretty much any common bench accessory is sized for 3/4" holes. I'd go for it! Unless you want to enlarge them all to 1" to use just the sjobergs dogs and holdfasts. I'd probably stick with 3/4" to have more accessory options from different brands.

[Cabinet Monkey]

Not that I can think of. Pretty much any common bench accessory is sized for 3/4" holes. I'd go for it! Unless you want to enlarge them all to 1" to use just the sjobergs dogs and holdfasts. I'd probably stick with 3/4" to have more accessory options from different brands.

20mm holes are also a common standard - especially among European manuf.

[JDuke]

Interesting
Today I pulled out a 3/4 twist bit, and ran it through a few holes, and they were still tight.

So I pulled out a 19mm forstner bit and ran it through and the dogs now fit perfectly.

Now for the interesting part.
3/4” is equal to 19.05mm such a small difference that socket sets frequently don’t have both.
The 3/4 should have opened up slightly more than 19mm bit

[alanealane]

You discovered a unique difference between how a twist drill machines wood compared to the geometry of a forstner. For a reason that I haven’t studied in detail, the actual size of a hole drilled in wood with a twist drill tends to be smaller than the nominal dimension of the bit. In my line of work building wooden wings for biplanes, I'm constantly reaching for a straight or helical flute reamer to open up holes in wood for aircraft grade bolts to fit through. The holes drilled with a twist drill almost always fit too tightly for a bolt to pass through easily until I ream the holes. And when I varnish the holes to seal the wood from moisture, I often have to ream again after the varnish cures, unless I immediately install the bolt into the wet varnished reamed hole. Forstner bits behave more like reamers and will give a better dimensioned hole. Glad it worked out for you!

[AHill]

Weird.  All my holes are 1" (whatever that is in metric) both in the benchtop, the vices or the side members.  My bench is circa 2004 if that is any help.

Same here on my Sjobergs Elite 2500.  I drilled 3/4" holes in strategic places to use my Gramercy holdfasts.  I do use Sjobergs bench dogs with the 1" holes (I think they are 25mm).  The Sjobergs QSH holdfasts with the screw down pad are too fussy to use for me.  I did notice online they are now selling 3/4" holdfasts, so they must have started marketing benches with 3/4" holes (their Nordic line?).