'Dadio throws a big top'. A reply to unjust criticisms

[treesnatcher]

Who is dadio?

search "Dadio" on here or you tube. Quite entertaining really:biggrin:

[Johny Walker]

are dadios new methods included in nptc up dates by any chance

[Sam Thompson]

This is a belated response to the closed thread ‘Dadio throws a big top’ posted 05-09-11. I‘ve considered the posted criticisms of the techniques used in the movie from an engineering perspective, using structural mechanics as a guide. Seems to me that several of the hurried criticisms don’t stand up to much scrutiny at all. Whereas, if one takes the time to absorb the content of the movie and all information the maker clearly provided, the mechanics can be analysed using basic structural mechanics and a basic knowledge of rigging

The geometry of the stem and the cuts (the hinge and the step) are all clearly there at the end of the movie and the text. Looking at the images, I have estimated the position of the hinge and I’ve also estimated the distance between the hinge and the pull line anchor point as maybe 6m (20’) from the fact that the stem above the cut is stated as 40’

I’ve estimated the offset (step cut) will provide a theoretical resistance of about 2kN (cleavage resistance) before the hinge starts to load. That’s the ‘safety valve’ preventing a barber’s chair (that’s my assumption anyway). This was a major issue for some Arbtalkers

The moment of resistance of the hinge wood can be calculated given the information in the movie. Admittedly, some engineering knowledge is a grasp of maths is required here. A basic cantilever calculation can then be applied to find the approximate load required to make the hinge yield. That’s the maximum force that could develop in the pull line because above that, the hinge will fail. Do the calcs as I have and you will find the hinge provides a moment of resistance (to rupture in bending ) of not more than 30kNm. So, with a lever arm of 6 m it will take a force of 5kN to break the hinge. That’s the theoretical max possible force in the pull line and I’ve probably conservatively estimated the moment of the hinge wood (I’ve used 80 N/mm 2 as the modulus of rupture which is probably high). That’s well within the permissible stress for the line. Dadio also gives information about the pull line ‘True Blue’ and clearly knows something of its properties. Its manufacturer states a breaking strength of about 32.3kN (I’ve assumed it was 12mm)

There has been a statement that this line could have been dangerous if it had snapped: well if it were steel then maybe. But it’s not; look at the rope manufacturer’s published data on its elastic properties. There might have been a danger to the cameraman from the block catapulting towards him but is it not possible that the cameraman was out of range?

Dadio discusses the size of the notch and the vectors evolved as the stem is pulled. No calculations needed really; you can see his assumptions were broadly correct: the stem landed where he engineered it to land!

So what have I learned from this exercise?

1. Absorb all of the information available before proceeding to criticise. I know its a hazard of instantaneous communication, but ignorance is still no excuse

2. Just because a technique is unfamiliar does not necessarily make it unsound

3. Conversely, those who may believe that because they have ‘always done it like this’ they are necessarily always correct, should perhaps reflect on the principal at 2 above

4. Having raised my head above the parapet I should now expect to receive incoming fire!

 

 

Interesting, but academic methinks.

[Pat Ferrett]

Dadio Rocks

[MattyF]

Dadio Rocks

Yeah he's my hero

[MattyF]

 

The thing is, I don’t think the landing of that stem was a fluke. Maybe it was foolhardy..but I’m not trying to argue that point.

 

I took exception to some of the posts because they hadn’t taken on board all of the judgements that had clearly been taken by the man on the ground

 

cheers

I could show you certain cuts ie Dutchmans ect that calculate leaning against standing wood and pressure they do work,mathematically .... But at the same time they don't hence why they are out lawed on most felling sights in America...timber has just to many factors ... If are American cousin wants to redifine Arb and felling to him and a skid steer pulling off moves that I personally don't think the risk in property or most importantly life are involved then it's up to people who whatch what they take on board... I have taken short cuts on jobs because I think I know it was right I would not post them and say look at my big balls I can put it were I want..Basically i couldn't give a damn but If some one gets hurt and leaves behind a family because they think that techniques work 100% is a problem... Dadio stated he split up with his girlfriend personally I think he was mentally unstable at the making of this vid mainly because he pushed him self behond the usual 10ft to make his felling

cut

[Pat Ferrett]

He's happy, in work, with a nice setup.

 

As long as nobody gets hurt then good on Him:thumbup1:

 

I aint saying anymore on the subject

[geoff]

Dadio stated he split up with his girlfriend personally I think he was mentally unstable at the making of this vid mainly because he pushed him self behond the usual 10ft to make his felling

cut

 

Bit extreme in your asumption in my opinion,or was it a dig?

Love a bit of discussion,its healthy,but I cant see the need for angled drivel,isnt that why the last thread got stopped?

[MattyF]

Yes and I hope this one does too ,if people are thinking it's a sound approach for removing unwanted trees!!, my last post I'm over this!

[geoff]

Yes and I hope this one does too ,if people are thinking it's a sound approach for removing unwanted trees!!, my last post I'm over this!

 

Haha:laugh1:,love the tactics...actualy,whilst on the subject,I would have gone for a less radical technique too with most of the fells Ive seen from Dadio,but then I tend to try & err on the safe side of safe.