High lift felling wedge question

[Marc Lewis]

You could just use no nails to hold the wooden or plastic parts in that's what I did the wooden one will stay in once used a bit the plastic one are prone to bounce out now and then hence the no nails works ok

 

'No nails' or silicon, should all do the job.

[Craiglr90]

I understood that the holes are to allow air to escape as it is a very tight fit also when it comes to changing them it's a 5 min job clamp in a vice chop though the wood just above th metal drill a few holes in to the wood it collapses in tap it upsides down knock the new one in and like people say 2 rings help to stop the end split better than 1

[Canal Navvy]

I use one aluminum ring and a short length of 63mm m.d.p.e. water pipe, fits a treat and makes the end of the wooden shaft more robust.

And free

[Gray git]

Do you put the aluminium ring on the plastic shaft or not bother, going to have to stick it into the wedge head at today every time I hit it it bounced out which was very annoying!

[cornish wood burner]

I was curious about that too, it's got to weaken the aluminium eventually. Not the heating, but the rapid cooling in water. Wouldn't it be better just to let the whole thing cool slowly?

In view of the temperatures and times involved it is highly unlikely to be a problem or make any difference. Strength of some aluminium alloys is improved by prolonged heat treatment (several hours) then rapid quenching.

[IanW]

all this drilling and chopping the old wooden shaft out must take ages... just turn the wedge on its side and give it a good firm hit with hammer, the wooden bit jumps straight out ready for new shaft..

 

Grey... I've put a couple of rings on my plastic shaft, I don't think it'll split but just incase. the shaft jumping out the head is annoying, not found a way to stop it happening yet

 

ian

[daltontrees]

In view of the temperatures and times involved it is highly unlikely to be a problem or make any difference. Strength of some aluminium alloys is improved by prolonged heat treatment (several hours) then rapid quenching.

 

I suppose I would just have to disagree with that on intuition. I agree that many metals are well tempered by heat, but what is being done here is to expand the metal to take a shaft then cool it around the shaft, so the metal is being cooled rapidly while under tension and as it cools that tension increases rapidly. I feel that microfractures are inevitable in this situation. They might not cause brakage immediately but they will not repair themselves even with subsequent heatings and will only ever get bigger and lnger. One day they might cause the wedge to shatter. After all, the things get punded with a sledge hammer. Any weakness will propagate.

 

Oh, who knows, it might take years and your wedge might fall in the river long before it breaks.

[cornish wood burner]

I suppose I would just have to disagree with that on intuition. I agree that many metals are well tempered by heat, but what is being done here is to expand the metal to take a shaft then cool it around the shaft, so the metal is being cooled rapidly while under tension and as it cools that tension increases rapidly. I feel that microfractures are inevitable in this situation. They might not cause brakage immediately but they will not repair themselves even with subsequent heatings and will only ever get bigger and lnger. One day they might cause the wedge to shatter. After all, the things get punded with a sledge hammer. Any weakness will propagate.

 

Oh, who knows, it might take years and your wedge might fall in the river long before it breaks.

Probably the worse thing appart from falling in the river is the internal stresses caused by impact. Heating might help this but at what temperature and time?

Aluminium alloys and heat treatment of, is a very complex subject and the composition would make a big difference.

If heating in the 280 to 450 deg C range cooling speed definitely can matter. Aluminium alloys can be treated/aged at 200 deg for several hours then cooled but as far as I know unless it is a very thin section then cooling rate is unimportant from this temperature. However the best thing is if you are concerned about the tension then cool slowly, either way then there will be no problem.

Using an oven for heat rather than a blowtorch obviously results in even heating eliminating

local overheating and heat stress so is a very good idea but probably best to keep at or

below 200 deg to be safe.