Multi Montis

[Dave Tyson]

I think Miles Moulding had some issues with thunderbolts (or equivalent) in Cwmorthin. A couple of bolts failed under very light loads after they had been in situ for some time - the head came off one and IIRC the other snapped a little way into the rock. It may be if the bolt is overtightened there is some residual stress which might cause microcracks over time. The problem is that even if you tighten the bolt so the plate hanger is just nipped someone may come along later and decide its a bit loose and tighten it further...

I'll be happy to use them for exploratory climbs, but wouldn't consider them for permanent placements due to the above issues.

Dave

 

[Mattrees]

It may be if the bolt is overtightened there is some residual stress which might cause microcracks over time. The problem is that even if you tighten the bolt so the plate hanger is just nipped someone may come along later and decide its a bit loose and tighten it further...

I'll be happy to use them for exploratory climbs, but wouldn't consider them for permanent placements due to the above issues.

Dave

I place throughbolts for belays buys that's more because of corrosion concerns - still no viable source for stainless multi montis.

I've had heads shear through being overtorqued, both by hand and with an impact driver, cleaning out the hole is important.

 

[Simon Wilson]

I've been testing these but I haven't made the time to write it up yet although it shouldn't be long. I want to encourage people to use them. They are far superior to throughbolts from a conservation point of view. Throughbolts are a curse and a menace to our caves and crags

Just a few comments.

Only use quality concrete screws and Multi Monti are one of the good ones. Avoid Thunderbolts and other cheapo brands. The one that failed in the BMC report was a Thunderbolt.

The 7.5mm Multi Montis (6mm drill) are pretty bomb-proof when used correctly. They have a simliar strength to an 8mm 'high tensile' (8.8 steel) bolt. 10mm Multi Montis (8mm drill) are nearly twice as strong - double bomber.

Follow the instructions supplied with them particularly about cleaning the holes.

They need to be drilled perpendicular and driven in straight. I would not recommend using an impact driver. It is best to be able to feel it as you screw it in and tighten to the correct torque. The correct torque is just tight enough to be secure and no more. Do not overtighten it.

They are easy to buy from a number of UK suppliers - just shop around.

Here you go - Multi Monti 7.5 x 60 at 30p each -  http://www.intertoolsonline.co.uk/heco-schrauben/fixings/masonry-and-concrete/multi-monti/multi-monti-hex-head-range

or

https://www.tradefixdirect.com/unifix-thunderbolt/heco-fix-multi-monti-flanged-head-75-x-60mm

 

[maxf]

So what hanger size is recommended for the 6mm drill (7.5mm screw) type ? Might an 8mm hanger be a bit 'loose' ?

 

[Mattrees]

So what hanger size is recommended for the 6mm drill (7.5mm screw) type ? Might an 8mm hanger be a bit 'loose' ?

8mm hanger works fine, the bolts will fall out if you're not careful. I tried using o-rings but decided it wasn't worth the trouble.

 

[SamT]

I've used a wrap of insulation tape. It gets squidged to nothing when tightened up.  Worked quite well.

 

[snoboy]

Around here we just snip a little square of inner tube and use that to hold the 8mm hanger on the screw.

 

[pwhole]

What about these? Would also help with the isolation of stainless plates from the galv/BZP of the screw. I've used nylon washers - they're hard, but they work. No visible rusting on the apparent contact point when the screws have been removed. But these would give a gradual tightening that might prevent over-tightening:

http://www.rhnuttall.co.uk/washers/neoprene-sponge-washers/

 

[Simon Wilson]

Does anyone have a source for 7.5mm (6mm hole) stainless anchors?

I've put two and two together. It was Mattrees who was asking about a rustproof harness because he is working where there is seawater and I guess that is why he wants stainless concrete screws.

Normally carbon steel screws would be better for most applications. I have been looking but haven't yet found a UK supplier of stainless concrete screws.

 

[Mattrees]

Does anyone have a source for 7.5mm (6mm hole) stainless anchors?

I've put two and two together. It was Mattrees who was asking about a rustproof harness because he is working where there is seawater and I guess that is why he wants stainless concrete screws.

Normally carbon steel screws would be better for most applications. I have been looking but haven't yet found a UK supplier of stainless concrete screws.

Yes, it's true, further looking on the forum will reveal the location. I want SS because of saltwater issues but also I thought they might be better if left in-situ long-term.

What's the advantage of carbon over stainless (apart from the obvious one of cost)?

For future reference, if anyone stumbles across this searching with similar purposes, Austrialpin make a stainless wiregate: http://www.austrialpin.at/safety-(1)/steel-carabiner/micro-inox-drahtbugel.aspx

Climbing Technology make a stainless steel oval screwgate krab: http://www.climbingtechnology.com/en/professional-en/connectors/oval-en/oval-s-steel-sg

 

[Simon Wilson]

Carbon steel much better mainly on price (30p) and availability. They are slightly stronger but that's a minor issue.

If you're climbing then you are only using them for a few minutes. You would only need stainless screws for a main belay if you were leaving it for an extended period. For a diving line it would be better to go up in size than to go to stainless.

I want to see people using concrete screws more and I don't want the lack of stainless ones to put people off.

 

[Mattrees]

If you're climbing then you are only using them for a few minutes. You would only need stainless screws for a main belay if you were leaving it for an extended period.

That's helpful, thank you Simon. It was that extended period I was concerned about.

 

[maxf]

I've been testing these but I haven't made the time to write it up yet although it shouldn't be long. I want to encourage people to use them. They are far superior to throughbolts from a conservation point of view. Throughbolts are a curse and a menace to our caves and crags

Just a few comments.

Only use quality concrete screws and Multi Monti are one of the good ones. Avoid Thunderbolts and other cheapo brands. The one that failed in the BMC report was a Thunderbolt.

The 7.5mm Multi Montis (6mm drill) are pretty bomb-proof when used correctly. They have a simliar strength to an 8mm 'high tensile' (8.8 steel) bolt. 10mm Multi Montis (8mm drill) are nearly twice as strong - double bomber.

Follow the instructions supplied with them particularly about cleaning the holes.

They need to be drilled perpendicular and driven in straight. I would not recommend using an impact driver. It is best to be able to feel it as you screw it in and tighten to the correct torque. The correct torque is just tight enough to be secure and no more. Do not overtighten it.

They are easy to buy from a number of UK suppliers - just shop around.

Here you go - Multi Monti 7.5 x 60 at 30p each -  http://www.intertoolsonline.co.uk/heco-schrauben/fixings/masonry-and-concrete/multi-monti/multi-monti-hex-head-range

or

https://www.tradefixdirect.com/unifix-thunderbolt/heco-fix-multi-monti-flanged-head-75-x-60mm

Any news on when your write up will come out Simon ?

A few people I have mentioned these to say they think they are dangerous and it would be nice to have some official test data in limestone as there is lot of anecdotal data so far.

 

[Simon Wilson]

Sorry, I've been a bit lax getting it written up but it should be out very soon.

I notice that Inglesport are now selling them. I've been using them and I am confident with them. But I wouldn't use the cheap copies to hang my coat on.