UKC

I want to put up some gym rings at home, like these: http://www.amazon.co.uk/Olympian-Gymnastic-Crossfit-Strength-fitnessXzone/d...

I'd like to put up a couple of permanent discreet fixings on the side of a wooden beam and put the rings up just when I'm using them. The beam is an engineered laminated beam 9cm thick and 35cm tall, so I'm thinking it will take my weight. I want to put the fixings on the side of the beam rather than the bottom so that it's less obvious to the eye.

I don't even know what to Google for the fixings, but came across these: http://stainlessdirect.co.uk/index.php?main_page=index&cPath=66_130 which take four screws, I think 5mm.

Is this appropriate, or will I end up in a heap on the floor?

In reply to Turdus torquatus:

Assuming the hoop is well attached to that diamond plate (riveted or welded) they look perfect and sensibly priced. I'd try to avoid drilling big holes for eyebolts which are your other option.

jk

In reply to Turdus torquatus: I'm not sure, what size screws could you get through? You've got to be really careful with this, I've heard of some awful injuries from people landing on their backs badly.

DISCAIMER: This is what I would do and not advice, anything you do is at your own risk.

I'd be looking at these

http://wireropeshop.co.uk/wire-store/index.php?main_page=index&cPath=17...

http://wireropeshop.co.uk/wire-store/index.php?main_page=index&cPath=17...

Probably the former as a drilled whole with the bolt all the way through shouldn't stress the wood much.

In reply to Turdus torquatus:

Hmmm, I'd want something a bit beefier than eight 5mm screws, especially as you will be hanging all weight on it, and possibly inverting yourself etc.

What is the beam holding up (a floor?), and is your additional weight going to cause an issue? I assume you cant access the top of it and just put sling round it?

You could drill a hole and thread a 8-10mm threaded eye bolt through, although as I understand it that will weaken the beam, so you need to be very careful. If its a part of a roof truss I'd avoid drilling holes in it.

In reply to Phil79:


^ For actual advice i'd go with this. It's foolproof and quick to do when you want to use it, just chuck slings over it and use a crab.

In reply to Phil79:

The beam is part of the roof structure of a large conservatory. There are two such beams. I can't access the top of the beam I'm afraid.

In reply to Turdus torquatus:
Ok, I don't know a great deal about this, but as I understand it glued laminated beams are used in high stress situations. If you have two of them holding up a conservatory roof, then I'd be very nervous about drilling holes through them as it concentrates stresses which are otherwise shared across the span of the beam. Which is further complicated by you hanging from them as that is additional stress for which the beam hasn't been designed.

Chances are it will be fine, but personally I wouldn't touch them without speaking to a structural engineer!

In reply to Turdus torquatus:

I'd be nervous putting them on the side rather than the bottom of the beam.

I know now this isn't what you're trying to do but I would have said the best method was 2 beams laid across the ceiling joists (so they are not mounted to the same beam), eye bolts with a plate and then noggins installed to prevent leverage with the eye bolts just running through them.

But these guys sell a gym ring mount that they are happy to be mounted with just 3 x 3/8" x 4" screws, even suggesting putting them in the same joist. So perhaps over-engineering is a bit paranoid.

http://blog.hammerheadstrengthequipment.com/2013/12/how-to-install-or-mount...

In reply to

Here's a picture which should clarify things: http://tinypic.com/r/ubyp/8

In reply to Turdus torquatus:

Have you checked with the owners of Kew Gardens that they wont mind you rigging up some rings?

In reply to Turdus torquatus:

9x35 is huge in the context of what's required to support a man and easily able to take the very small twisting load a human weight will apply at what, maybe 8cm off centerline.

http://tinelok.com/grade-5-vs-grade-8-fasteners/ Sorry, it's imperial and for machine screws but good enough for a quick and dirty check. 0.2" grade 5 roughly corresponds to a good quality 5mm woodscrew and you'll see it'll support a remarkable 2100lb in shear, nearly a ton. Pick the size down to be on the safe side, wood screw threads tend to be deep and you still get ~600kg/screw. Assume they're not sharing the load equally and de-rate further as the soft glue-lam beam will allow some bending before failure rather than a pure shear load it seems even one screw of adequate length would still suffice.

4x decent quality 5mm screws evenly loaded and well supported in shear would support a car let alone a man.

jk

In reply to Bjartur i Sumarhus:



I know. Not the Death Star minimalism I'd hoped for, but the Mrs loves her plants.

In reply to Turdus torquatus:

As jkarran says, that's one huge beam, so can easily carry the load.

If it were me, I'd just drill right through and whack a sling through it as and when you want to use the rings. Not as convenient as a permanent solution, but it may be more discrete.

In reply to jkarran:

This thread is a bit Call My Bluff, but yours seems the most convincing answer. Thanks all.

In reply to Fraser:

I'd use the screw bolts Mike S suggested up thread.
Your Mrs can use them for hanging baskets when you're not using them.

In reply to Phil79:


I've designed several glu-lam structures and it's always been for aesthetic reasons, never for stress/load reasons.

Such a small hole in such a chunky beam really won't make any difference to its performance.

In reply to Turdus torquatus:


We'd best hope it's right then as I'm not actually that sort of engineer
jk

In reply to jkarran:



You're a telephone hygiene engineer aren't you? Bugger.

In reply to Turdus torquatus:

Something like that
jk

In reply to Phil79:


Good point, and we don't know how much of a lard arse this bloke is!

In reply to Mike Stretford:

.


This made me laugh.
If he does what you say, has an accident and tries to sue you for bad advice you're sorted with that one...haha
ffs

In reply to jimjimjim:





Ffs yourself.

It's a fairly common forum phrase, tongue in cheek, an I doubt anyone is under the illusion it it offers anyone any legal protection. It's just to emphasise to the guy that he need proffesional advice if he is not confident in his own judgement.

In reply to Mike Stretford:

Calm down youth...
disclaimer: I will not be responsible for my comments or resulting arguments with other users that can't back up their talk.
xx

In reply to jimjimjim:
Just explaining some common parlance 'youth'. Bizarre reponse.

Can you help Turdus with his rings or not?

In reply to Mike Stretford:

"Can you help Turdus with his rings or not?"

Oo-er!

(Well, this thread was already going off-kilter anyway...)

In answer to the OP, that beam, as has already been stated, will easily support your weight. I don't like the idea of drilling through it and putting slings through the holes - you would need an indiscrete and sizeable hole in order to facilitate this. I would drill through the beam about 8cm or so from the bottom of the beam and, using suitable bolts, affix a couple of bolt hangers to the beam. That way the rings can be easily removed, the hangers won't be particularly unsightly, particularly if you paint them first, and you can use them tho hang other things from them if you wish to.

Just my two-penneth.

DISCLAIMER: I am in no way responsible if your wife doesn't like my suggestions!

In reply to handjammer:

Sounds like the best idea to me

Disclaimer: I have no idea if that's the best idea ......youth

In reply to handjammer:

Say no more

http://www.reddit.com/r/homeowners/comments/2ksp40/will_installing_sex_swin...

Work safe for most I'd say.

Those guys seem to know their stuff and not a 'disclaimer' in sight.

In reply to jkarran:

Would you top rope of 4 5mm wood screws? how deep would you want them?

I doubt they would be evenly loaded.

In reply to Mike Stretford:


Given it's a 90mm beam 75-80mm screws are available, even in pretty soft wood they'll snap before they pull out.

Well since top-roping is 2 to 4x the load we're discussing (2 people) it's a slightly unfair question but assuming we were talking about an equalised pair of well made eye-plates screwed to good wood with good quality 5 or 6mm screws. Yeah, why not, it's in the same ballpark strength wise as what I'd usually be happy to belay off: 2x ~12kN (in a good placement) nuts.

Even if my admittedly quick and dirty estimate is a full order of magnitude out they're still plenty strong enough for doing pull-ups. The plates and the plate-eye join would be my concern, not the screws.

A more empirical approach... Have you ever ripped a screw-on hold out of an indoor wall? The're usually held on with 3x 3.5 or 4mm screws in 19mm board, significantly less than I'm suggesting screw wise.


I suspect so long as the fitting isn't completely botched there's enough give in softwood to achieve good load sharing between screws.

The OP should do as he/she sees fit.
jk

In reply to jkarran:

Yeah it'd be plenty strong enough. Worked in the building trade all my life. People who know little about these things love to go for over kill.

In reply to jkarran:

I think it's a fair question, they could be dynamically loaded which will put much more force than a top rope would as there's no elastic in the system.



I wouldn't, and I think climbing anchors are good comparison as injuries from falling on your back can be horrible. Yeah, you'd think they should be ok, but wood screws aren't rated, quality checked pieces of gear. A bad batch, or overtightened so you start to strip the tread you've just created, or a bit loose so there play which gradually wears the thread. I'd be happier with a nut and bolt every time.


Of course, but if someone has to ask, I'd feel obliged to point out the safety implications.

In reply to Turdus torquatus:

Danger!!

you say " 9cm thick and 35cm tall," looks as if you meant 9 tall 35 thick ?????

BIG BIG difference

In reply to Mike Stretford:


No elastic... How stiff are your arms?


We'll have to agree to disagree. FWIW I have no objection to the through bolt suggestion except it leaves big holes when removed.


Fair enough.
jk

In reply to jkarran:


Pretty stiff at full stretch.... but yeah in normal circumstances it would limit the dynamic load. Still, the system will be subject to repeated dynamic load so I would avoid the wood screws. Yup, agree to disagree.

In reply to Mike Stretford: and others

Its not going to make much difference how its fixed . .............. as

if, as it looks its a 75mm depth member with all reedy some loading on it? [ hard to see the pitch of the glass ]
after the first use and subsequent sweeping up and replacement of the DG. units, it going to be a one time use!!!!!!

In reply to google:

Maybe the image I posted isn't orientating correctly, but the beam is definitely 35cm tall. That is to say, in the direction of the main load.

In reply to jkarran:


The eye plates I've been looking at have a break load of 600kg to 1400kg, depending on size.

In reply to Turdus torquatus:

Ok that so reed up on the equal or neutral access load and fix close to IE; the center

http://en.wikipedia.org/wiki/Neutral_axis

In reply to google:


Depends on how much of a fat bastard Turdus torquatus is!

In reply to Turdus torquatus:

That's mass not load.

Here's an article on forces on gym rings, now alright you probably won't be doing the same things but it gives you an idea of the peak forces a 68Kg bloke can put on them.

https://ojs.ub.uni-konstanz.de/cpa/article/view/1635/1537

In reply to Turdus torquatus:

Thinking back to how I put my finger board up, that's hanging on 4 X 75 mm screws (4.5 mm I think but possibly less). Obviously the load on a finger board is less dynamic but the fixings you link to take 4 screws per fixing so you should be fine IMO.
Saying this, having load off centre isn't ideal so I'd look at shutter hinge style strap fixings where the load is straight down.

In reply to Mike Stretford:


That's how the manufacturers specify it. perhaps they're being shoddy because they don't expect gymnastic applications.

In reply to Turdus torquatus:

Pretty much. They aren't expecting dynamic loads so they give weight, they're for hanging stuff. They give safe working load 25% of breaking weight.

http://www.stainlesssteelfittings.co.nz/eye-plates/4-eye-plate-diamond-stai...

In reply to Mike Stretford:

The paper you linked to referenced some other work which had measured peak forces during gymnastic manouevres of eleven times body weight. I'm only going to being doing leg raises, pull-ups etc, but I'd really need to think again if I were to also use this for the sustained and rhythmic activity of two people in a hammock.

Thanks again for everyone's advice. I won't ask about my plan involving a lark's foot, dyneema and a snapgate to attach the rings to the plates...

In reply to Lusk:

If it was me would need I beam

Lancaster over black hill be careful they crash up there !