Thread: Drilling pilot holes for post stirrups

Hi Paul and welcome

I've never had an issue just holding the drill straight and drilling right through.If you need to hold a set square up against the drill and line up the drill bit parallel to that it could help.

Having said that, I don't think you should rely on a stirrup for strength as such. It will only ever provide "strength" one way, if at all. Stirrups will provide support. The strength, and the alignment (vertical both ways) should come from the frame you build on those posts, not the posts themselves. Regardless of how tight you do up a bolt in a strirrup, a 2 or more metre post will still sway off the vertical if left unsupported by other means.

So in that case, either a U shaped or L shaped stirrup will provide the necessary support, with the frame providing the "strength".

Thanks John, I appreciate that information. I tried previously to drill straight through a stirrup and post when installing a merbau screen, but I couldn't get it straight. So I thought there may be a knack to it.

Good to know that the support of the structure has more to do with the frame than the posts as I now may choose L shaped stirrups instead because it's easier. With L shaped stirrups, do you suggest bolt, nut and washer or just hex head batten screws 14g (or similar)?

Thanks again, Paul

I knew a builder who used only 2" (50mm) x 3/8" hex head coach bolts, purely because he couldn't drill straight through and make it look nice, Hex head coach bolts also did away with the unsightly look of a nut and thread. If you are using permapine/CCA etc use galvanised bolts instead of zinc plate, rusting of a ZP bolt can occur quite quickly with treated timbers.

If using squared beams for the uprights, you should be able to position 'em in the stirrups, mark 'em, remove the beams and lay them flat in a drill press. But I don't know anyone who goes to all that effort.

Me, I drill half-way from each side using a slightly under-sized drill bit. Then eye-ball through the hole to see which way it "bends" and re-drill using the correct sized bit applying a bit of side pressure to cause it to "adjust" the direction of bore.

This won't work for drilling metal - and gives the "engineers" a fit - but it works fine for wood.

You might be surprised at just how easy it is to get them square enough.

AS Scrapwood said.

Use hex headed coach screws, one on each side. Drill about half way through from each side, if they don't line up it doesn't matter.

Originally Posted by Avery

AS Scrapwood said.

Use hex headed coach screws, one on each side. Drill about half way through from each side, if they don't line up it doesn't matter.

What they said. A bolt right through would be overkill. All the weight is vertical & the coach bolts don't do much more than locate the timber in the stirrup. I use gal washers so you don't lose too much zinc when you tighten the coach screws.

I use the same method as skew chiDAMN
les

Thanks everyone. I like both ChiDAMN's and Scrapwood's ideas. It gives me a few options. Thanks again for all your advice.

Just one final question that comes to mind. When attaching a stirrup to the post using coach bolts, do you use a washer also or just tighten the bolt directly up against the stirrup. Sorry if it's a silly question - still learning.

Paul

Always use a washer - as you tighten up the nut any abrasion of the metal [removing the protective gal] will be on the washer and not the stirrup - I also have used gal washers in the past rather than just plain.

Re the lining up of the holes - I have used the undersized bit method before but I also draw a line from the hole on one side to the hole on the other side [as the metal holes are not always perfectly in line horizontally], this give me something to eyeball as I'm drilling and helps to keep me in line.

Hope it helps, regards,
Bob

Excellent, thanks for your help Bob, it certainly helps.