Cast iron outdoor chair refurbishment - threaded inserts and machine screws?

[TJC]

Hi all, was hoping for some quick advice.

I'm restoring a cast iron garden chair which someone gave me. All the wood is shot but easy to replace, I had a question on the method of attachment.

The original construction was with threaded inserts and machine screws, as pictured. Any reason why I shouldn't do the same again? It seems the best choice, but I may be missing something? Obviously won't reuse the rusty old ones pictured, half had to be cut out anyway...

 

[bjm]

Only issue I could see is that seasonal movement of the wood might loosen the inserts?

 

[TJC]

Would that be more pronounced than with any other fixing?

 

[AES]

Would that be more pronounced than with any other fixing?

Don't think so. But if in doubt a drop of Loctuite thread locker.

But what new wood are you using? If oak then use Stainless Steel bolts (with proper length plain portion please).

SS doesn't react with oak when wet (turns an 'orrible black-ish colour if MS or other metal)), and using bolts with the correct length of non-threaded portion reduces the tendency for water to creep up the threads and into the wood (capillary action).

If you can't get bolts with the correct length of non-threaded portion, get them over long. You can use a die to chase down the plain portion until it IS the right length, then (if necessary - probably will be) cut the whole bolt off to the correct overall length.

HTH

 

[scholar]

I have used threaded inserts to refurb a teak slatted/steel framed table and chairs. They are the best solution.

you can get stainless steel threaded inserts and obviously bolts and washers. The SS inserts are more expensive, but probably the best - otherwise they are some alloy I think.

I have found that a good (powerful) cordless drill with hex driver is the best way to insert the inserts (slow but firm) plus some Vaseline.

Would like to see the finished result

cheers

 

[Neil S]

I had a disappointing experience with the threaded inserts. The inserts repeatedly broke off at the head where the hex key engages to drive them in. Or sometimes the insert would completely break in two lengthways.

My inserts were from screwfix which might explain my bad experience. where do you get quality inserts from?

I also have a cast iron garden bench similar to the original poster but the slats were fitted with bolts that went right through with regular washers and nuts on the back.

Thanks

-Neil

 

[AES]

Can't speak about Screwfix (I'm in Switzerland). The ones I buy locally are - apparently - made here and are fine. I can only suggest you try a decert tool-hardware retailer (if you have one nearby) and look for a well-known manufacturer name.

Sorry, I can't help more - somebody like "GKN" (Guest Keen & Nettlefolds) USED to be a good name but I haven't lived in UK for almost 40 years now and I THINK they're no longer around (gone bust???)

But any decent threaded insert ("nutsert") shouldn't break if you don't over-torque then - but BEWARE, SS fasteners of all types will GENERALLY accept less torque than MS (for example).

 

[J-G]

But any decent threaded insert ("nutsert") shouldn't break if you don't over-torque then - but BEWARE, SS fasteners of all types will GENERALLY accept less torque than MS

The only ones I've bought have been what I consider 'Mazak' and although they mostly do the job, the hexagon deforms far too easily and getting them out again is usually difficult if not impossible.

I used to drill the hole so that the bottom end would just fit but soon found that I needed to drill it the core diameter just under the 'head' (I'm talking type 'D' which has a flange at the top). I recently fitted 66 M4s to my CNC Table and only had one failure but now I know Stainless are available I'll be looking at those when I need more stock.

 

[TJC]

Thanks all, very helpful. AES, it's just varnished softwood for now, perhaps something nicer further down the line. I can get the length of screw I need off the shelf so much easier, but thanks for the tips.

 

[Rorton]

I had a disappointing experience with the threaded inserts. The inserts repeatedly broke off at the head where the hex key engages to drive them in. Or sometimes the insert would completely break in two lengthways.

My inserts were from screwfix which might explain my bad experience. where do you get quality inserts from?

I also have a cast iron garden bench similar to the original poster but the slats were fitted with bolts that went right through with regular washers and nuts on the back.

Thanks

-Neil

I had exactly the same - poor quality - I bought some from Axminster before, and they were much stronger.

I found with the Screwfix ones, if you drill your hole, and then put a slight countersink on the hole after - its enough to allow the flange part of the insert to seat flush with the surface without cracking/splitting

 

[TJC]

Mine are stainless steel from amazon, they don't look too flimsy, will see when they arrive later. I'll take the countersink suggestion, thanks. Also I'm only driving into softwood, so not too concerned...

 

[Rorschach]

Could you not just tap the cast iron directly for the fixings?

 

[TJC]

The iron already has ears with mounting holes in, then a channel. Seems easier to bolt through the existing holes.

 

[Mick p]

Thanks all, very helpful. AES, it's just varnished softwood for now, perhaps something nicer further down the line. I can get the length of screw I need off the shelf so much easier, but thanks for the tips.

TJC don’t waste your time and money with softwood and varnish you will only be doing the same job in the next couple of years
look for some old hardwood flooring check out any skips where they are doing a building renovation as I did and use as previously stated stainless steel dome headed hex bolts
i done mine six years ago and its still in very good condition

 

[TJC]

Hey Mick, broadly I think you're right. I already had some 3by1 and the varnish is the last of a tin from something else so it hasn't really cost me anything this way either. So far the cost is just the box of threaded inserts.

If it only lasts 2 or 3 years that's ok with me, it isn't taking much effort. By then I'll be able to do it properly!

 

[MusicMan]

I have had very good success with threaded inserts. No idea which make, I just got them off eBay. Plated rather than stainless, am sure you'll be fine with yours. And when you come to replace the wood you can reuse the inserts!