Tree fixings

[Treelighter1980]

Hello ladies and gents!

 

So firstly , I'm not an Arborist. I'm a designer on an illuminated trail in Scotland and am looking for some solid advice regarding a possible method of fixing some items to trees in a local authority managed forest/country park in Scotland. 

 

The forest in question is mostly made up of Douglas Fir, Sitka Spruce, Scots pine and Japanese larch. Although its a country park mainly for the enjoyment of the public, when trees are harvested they are done so mainly for commercial reasons and or due to weather damage/ unsafe ( scotland is not exactly known for its tropical climate....)

 

We need to temporarily install some small loudpseakers to the trees, and this is done by way of a speaker bracket that has 4 fixing points. Speaker itself is not heavy at all ( 1kg ish ) 

Ideally we'd like to use screws to achieve this but a back up of attaching the bracket to a small pad of marine ply and then strapping this round the trunk with an endless ratchet strap has been formulated, however if possible we'd like to go down the screw route. Purely and simply down to time and cost.

 

I've done a bit of research and read that the best screws to use would be of aluminium or stainless steel type and obviously I've gone for the smallest Stainless Steel screw there is which in turn with weight considerations would be 30mm screw length and 4mm width. Once the bracket is on the tree only about 20-22mm of screw would be penetrating the bark and into the tree "meat".

 

The event itself runs only for 3 weeks and we would be installing the items 10 days prior to the show opening. At the end of the event run the brackets would be removed together with EVERY screw ( we wouldnt be able to get the brackets off the tree trunk otherwise )

 

The rangers are understandably worried as they kept reiterating that the trees will be eventually felled for harvest and they don't want the trees damaged as this would affect their price. 

 

After watching a few sawmill videos and reading some forestry literature would i be correct in thinking that the outer material is stripped back quite a bit so a 20mm screw path wouldnt be noticed or interfere much in the harvesting / processing ? 

 

Im obviously mindful of damaging the tree by means of giving a path for insects and funghi to harm the tree....Would spraying the screws with copper solution be enough to act as a defense against introducing an infection into the tree? Or would the use of copper solution effectively poison it?

 

As mentioned, I'm not an Arborist however I'd rather be able to come to a mutually beneficial method with the rangers rather than just be told no. At the same time I love the outdoors and would hate to be the cause of a tree being infected by funghi etc.

 

Am I flogging a dead horse here or do you think the above screw method and execution is viable?

 

Thanks for your time

 

Julian

[monkeybusiness]

If they are only temporary then strap them on using your plywood method. Screws into bark (and not relatively deep into the timber below) will potentially fail anyway. 

[Treelighter1980]

Hi Monkeybusiness.

 

Thanks for the reply

 

Im guessing that you are basically saying that screws would damage the tree enough to cause issues?

 

J

[scbk]

How many speakers? A few or hundreds?

Small ratchet straps at a couple quid each doesn't seem a huge investment, and reuse them for many years and events to come

 

https://www.amazon.co.uk/FixKit-10-Piece-Ratchet-Metres-Maximum/dp/B07BCXNCSS/ref=sr_1_7?adgrpid=52569208069&dchild=1&gclid=Cj0KCQjwit_8BRCoARIsAIx3Rj4D0p3lBv9jP14NgKROygcv4TEZs7uOsBwOesnIQETaV5maLmq_s2kaAvDOEALw_wcB&hvadid=259105460341&hvdev=c&hvlocphy=20342&hvnetw=g&hvqmt=b&hvrand=8875248119825316789&hvtargid=kwd-320128442874&hydadcr=883_1804250&keywords=25mm+ratchet+straps&qid=1603837942&sr=8-7&tag=googhydr-21

you can probably get them cheaper

[Treelighter1980]

Hi Scbk

 

We are looking at 80 speakers in total. Only one speaker per tree. 

 

The only issue with the ratchet straps is the time involved. We've had our build time cut drastically.

 

The screw method takes one person to put the bracket on whereas the ratchet strap method takes an element of pre prep , cutting the ply pad, fixing the bracket onto the pad and then having one person hold the pad while the other gets the strap in place and tightened )

 

As mentioned we are fine to do the ratchet strap method, its just the time involved when its 80 speakers.

 

If we can get these on without seriously damaging the tree with screws the its just to see if its viable

 

J

[scbk]

If it was my trees and timber, I wouldn't want someone putting hundreds of screws round the woodland.

 

Even cheap rope (like 8mm blue polyprop) would probably do, assuming no risk of falling on the public.

I don't know what the speaker bracket looks like, maybe you could ditch the ply and tie the bracket directly. Or use planks, faster to cut than ply

[Treelighter1980]

Bracket shown below. 

 

The speakers would be on the trees edging the path ( about 1.5m from path edge ) and the public would not be able to get to them anyway as we have a rope barrier both sides of the full length of the path/trail which is about 1.2 km long.

 

Blue polyprop or similar would look a bit out of place as these trees are also being lit individually.

 

On closer inspection of the photos it looks as though the vast majority of the trees are Sitka Spruce , so a relatively thin bark. These are all pretty mature trees. I would imagine most of them have between 700 - 900 mm dia trunks.

 

J

 

[roys]

Big cable ties are quick to use and cheaper to use, would probably cost the same as your SS screws and just as quick, in fact quicker on the day but overall after the ply prep probably the same. The more friendly way is the ratchet straps as they are reusable but if this is a one off event then cable ties. If it is a one off event then they have already spent a few quid on the speakers mmmm.

[monkeybusiness]

Cable ties are a great shout - I bet you could fit them straight to the brackets and not need the plywood backing either. You may need to drill the holes out (or drill a new pair of central holes) to accept the big ties possibly. 
 

[Logdaft]

Hi Treelighter1980,

As roys & Monkeybusiness said, I would also go for big cable ties & join them together if needed to go round the trees & then no need for plywood backing. You don`t say where you are, but if your near Inverness HIS have big cable ties, I saw them when I was in there last week.

 

*Edit* You could also buy a reel of small diameter black plastic sheathed copper cable, cut it to length & twist it @ the back of the trees to tighten it, this way it could be easily removed & reused.  

Edited October 28, 2020 by Logdaft