Fixing door jambs to steel post - advice please.

[RogerM]

This coming week I need to install a frame for bifold doors. The head will be bolted to the flitch beam with 10mm stainless steel threaded bar which will enable me to adjust the fit with a spanner from above which ought to be easier than trying from below. The weight of the frame and glazed doors will be somewhere around 220kgs so needs to be something substantial. Then the 45mm thick door jambs need to be attached to the corner posts which are 100mm sq in 10mm galvanised steel.

So, how would you attach the frame (seen in the background) to the posts?

One thought is to drill and tap threads in the post. This is not something I've ever done, but I guess shouldn't be too much like rocket science. If this is the chosen route, any advice from those familiar with the process?

Alternatively I could drill right through the post and simply use a nut and bolt. The nut on the outside would be lost in the cladding which will be 30mm of celotex insulation covered by 20mm of iroko to match the frames and doors. Perhaps minimise the projection by using a half nut? In each case the head of the bolt will be recessed in the frame and covered with a matching plug.

Ideas please!

 

[Tinbasher]

Drill and tap into the posts to take countersunk stainless setscrews?

 

[Dominion]

A fine thread countersunk TEK screw would work. You'll have to Google search as I'm not allowed to post links.

 

[jasonB]

TEK screws were used to fit these

Into this

J

 

[RogerBoyle]

I was in the same situation 7 years ago
I drilled and tapped them only took an hour and a half to do (8 bolts) and was a good solid fixing
I decided that should the need arise to replace the frame in the future then it would be a simple matter
to undo them with the minimum amount of damage.
I countersank the heads of the bolts and washer and cut some plugs to cover them

Roger

 

[gardenshed]

Roger, TEK Screws, TEK Screws, TEK Screws, TEK Screws,

 

[RogerM]

Thanks guys. Looks like TEK screws win out, and they also have the advantage that if I'm not happy the holes can just be drilled out and my neighbour will come in with his tap and die set and thread the holes for me so long as I buy the beer.

So far as the top fixings are concerned, I'm attaching to a flitch beam (10mm thick steel plate sandwiched between 2 wooden beams 225mm x 50mm). I've planned to suspend the top using some 10mm threaded stainless steel rod let right through the depth of the flitch beam so that all the adjustment can be done with a spanner from above. Holes are at 400mm centres with a cluster 100mm apart at the end where the doors gather when slid back as that is where the weight will be. So, with 9 holes in total I was planning to use the ss threaded rod at each end and in the centre and heavy duty screws in between. What do you guys use? Is what I've planned overkill or does this sound like a plan?