Oversized screw holes for adjustability?

[Shawn Traylor]

Hi 👋 -
New member and couple-years in beginning woodworker. Building the miter shooting board in Mike Pekovich’s book, where he writes that he screws the fence to the base using oversized holes for adjustability. It sounded simple, but now I’m trying to understand how it works. How would an oversized screwhole not lead to unwanted movement? Any advice?

[Mitch schiffer]

Welcome to the forum I'm fairly new here as well. I don't do much of any hand tool work, but I do use oversized holes for attaching drawer fronts on cabinets. Generally I haven't had issues with them moving around when the screws are tight. I do use a screw with a larger washer type head for this. Just a thought maybe you could add some sandpaper in-between the 2 pieces to increase the friction lowering the chance of the moving. Good luck on your project.

[Anuj Prateek]

Use a oversized hole and use nut & bolt instead of screws.

On my shooting board I have used 1/4" bolts. On on side hole is 1/4" and on other side it's 3/8". On oversized hole side, you can use a wing nut or knob. Hand tightening them exerts more than enough force to prevent fence from moving. If your board is slick, you can stick some 80 grit sandpaper under the fence.

Alternatively you can screw the fence and use shims as needed.

[Rich Engelhardt]

Any time I need an oversized screw to help against movement, I drill the hole slightly larger and use a Kreg pocket hole screw.

[Carl Beckett]

This only works if the screw or bolt that you use is not tapered on the shoulder. Traditional flat head woodworking screws are tapered so that when you tightened it it will center on the hole. As suggested use a screw tape that has a flat shoulder that pulls against the word so that it can be off-center of the hole and still squeeze down

[Thomas Wilson]

I made a two-piece fence. The back fence is glued and screwed very securely. The front fence is just screwed. If it needs adjustment because of compression or just creeping of the joints, I can take the front fence off and plane it down a bit. So far, the fence has remained square.

My thinking, despite having no experience with adjustable fences, is that the oversized holes would allow a bit of creep in the fence no matter how tightly it is screwed or bolted.

[glenn bradley]

Welcome. I use threaded inserts of t-nuts for attachment. A tight-hole for a 1/4"-20 near the plane chute and a 3/8" hole with a 1/4"-20 at the end away from the chute. I add a large fender washer to increase the contact surface. Although I check the alignment often I have only had to correct it a few times over the years.

472723

This also allows for a bit of over-angle or under-angle if that is desired.

[Shawn Traylor]

Ah! Bolts, not screws was the critical piece I was missing. Makes sense now. Thanks!

[Shawn Traylor]

Thanks and appreciate the photo.