agg221

You're welcome - Fig.1 in the paper is particularly helpful. Also worth noting that they have the feeding location as the twig/stem crotch rather than the leaf/stem crotch - this is very recent work by some very respected experts so I would go with this rather than my originally stated location. Alec

The infection is not initially transmitted by the beetles burrowing but by them feeding. They do this at the base of the leaf stalk (leaf/stem crotch). The spores are rubbed off the beetle and enter the wound. As such, pretty much any elm can be infected (there are English Elms under 2' high which have been killed recently). The beetles prefer to fly at about 6m, so as long as they can find food at this height this is usually the limiting factor. It's only when food gets scarce that they come down to the smaller saplings. Beetles prefer to lay eggs on weakened trees which have been infected - these give off chemicals which attract them. This can cause secondary infection. There may be a link between survival and the structure of the wood cells, and also leafing out time of a particular clone. If you are interested, this new paper explains in some detail: Santini A, Faccoli M (2015). Dutch elm disease and elm bark beetles: a century of association. iForest 8: 126-134. Alec

Treatment is a fungicide. It is effective, but it has to be repeated every year. Elm disease is worst in years when there are a lot of spores and a lot of beetles. It's a bit like a person getting a cold - you inhale cold germs pretty much with every noseful of air but you only get a cold when the conditions they land in are right and there are more incoming germs than your system can quickly kill. Some trees (genetically) can tolerate a higher dosage of fungi before they are affected. Some are less attractive to the beetles. Beetles don't like to live in some conditions. If you happen to treat a tree in a year which favours the spores and the beetles then it is won't be infected. If you then don't treat it in other years but there are fewer spores/beetles around, or the tree happens to be less attractive to the beetles, you may well not see it get infected until the next time there is a bad year. The critical dose is very variable. English Elm virtually seems to die from a single spore-carrying beetle whereas other strains such as Huntingdon Elm (as per MattyF's pictures) takes a higher dose. Some strains/hybrids can tolerate such a high dose that they are effectively immune in the field. Another factor is the health of the tree. Like people, a young, vigorous healthy tree is far more likely to survive than an old, weakly growing tree in poor health. Returning to the original point, the need to treat annually is the reason it has been abandoned for all but a very small handful of trees. I also vaguely recall that the effective fungicide has now been withdrawn for this purpose. Alec

That about covers it - not very applicable to trees which is why I wasn't sure why the op mentioned it:confused1: Alec

I would still go for winter, after you've had the best of the fruit. It is a lot easier to see branch structure then. Alec

I bought a couple of Mora lives at the show. A 106 which is the short straight one as I preferred it to the long blade and a 164 which is the single edge hook. Alec

I think I'll leave them as they are. The first one is a bit 'tool marked' but they have got progressively better and I reckon they are fully serviceable like this. I might scrape the flat handled one a bit as the shape means it crosses the grain a few times (even though I used a naturally double-curved piece of wood) so it is hard to get the fibres off. Alec

Younger daughter then wanted one too, but she didn't want a heart on the end, she wanted a butterfly:

Elder daughter then wanted one so I made this:

I have fancied having a go at spoon carving for a while and got the chance to have a play at the spoon workshop at Wierd & Wonderful Wood. Made this:

Bark can be a useful part of the whole but elm morphology is complex. Richens' papers of the '50s to '70s provide the best guide to consistent features and how to interpret them but he eventually concluded that in regions where different strains are present you end up with a continuum of features. This supports the view of strains of a common species (U.minor) rather than distinct species. Hence the need for multiple feature analysis. I don't fancy trying to measure Ra on an elm leaf - I don't fancy trying to get a baseline! Alec

We went on Saturday. Really good as always - the daughters did a lot of the activities while I whittled a spoon (that is one seriously addictive hobby!). Daughters went for mint choc chip. Alec

You could try starting by identifying a school which runs a Forest School. They are usually very keen to have extra help, you would be under their insurance and they will do the CRB check. Other option would be the local Scouts which will do the same thing. Alec

Corky wings are standard on the English Elm strain. Leaves can vary depending on local growing conditions but it may be a hybrid with another U.minor. Less likely to be a hybrid with U.glabra as the leaves do not look as big as this usually produces. Alec

My elder daughter got invested into Beavers on Monday. They would love something like that. Should make for a very rewarding evening. Alec

Dimensions would be useful to assess how long it will take and hence cost. Location would also be useful. Milling will create lots of sawdust and however careful you are some will blow around and be left. You will minimise damage to the ground if you mill fully where it lies with an Alaskan and carry sections out. If you want fairly thick section (2" or more) I wouldn't worry about trying to use some chainsaw/some bandsaw but if if you want thin boards eg floorboards I would break it down with the Alaskan and then band mill the sections to reduce waste. Alec

Any idea on lengths on these? I have to head that way at some point soon so may be able to do it if nobody closer does - just trying to size up how much of a day it would take. Alec

Is this the post you are referring to? http://arbtalk.co.uk/forum/tree-health-care/78411-anyway-dodge-elm-disease-2.html Interesting that the tree which failed was Z.carpinifolia - would explain why it had previously been mis-identified as a hornbeam. Alec

I will try to find some holes Welding thin 316 is not difficult. I am not the world's best welder, but I am pretty good at it - I have run a whole load of seams in 1mm 316, both in butt and corner lap configuration. Some of the butt welds were unsupported freehand across about a foot and I managed not to burn holes and where I did, to fill them in again. Finding a nuclear coded welder is harder, but you don't need one for this. If you just want a fabricator I can find you one who is very reasonable if you want me to drop you a number (they're near Newmarket but if this is to be trailable it shouldn't be a problem). Dished ends are good, but the fundamental problem here is that the heating in a horizontal barrel design is non-uniform. This creates differential stresses, it has to go somewhere and so it warps it. Extra strength does not help you enough as the material is too thin to resist the stresses. Graham, I would be very happy to come over and see your set-up. I can even try to explain what I am on about in English! Alec

Check the clamps on your uprights. I suspect you will find that on one the scale on the upright is against the wedge behind the U of the U-bolt, the other against the cross-brace. These are at different heights, hence even if you keep the mill flat to the log you will get a wedge. If so, you need to turn one of the uprights round (if you still have the instructions you can see this marked up, but it will probably be the outboard one, since the inboard one has the skid on and is harder to get wrong). Alec edit: just noticed this is the small log mill, so a single upright. Suggests you are pushing down too hard on the powerhead, causing the bar nose to lift.

That's bigger than even I can do - I'm limited to just over 80" throat! Need some pictures when you do that one. Alec

OK, 97cm width determines the mill size you will need. A 36" mill is actually 34" throat, so won't quite go through. You would need a 42" bar minimum to get full capacity. You could skim a couple of inches off each side at the widest point, losing only bark and sapwood, but rolling it several times to do this with a mill will be painful unless you have access to a teleporter or a tractor and chains. Personally, I would skim this off with a side axe in less time than it would take to fiddle about rolling it, but it depends on whether you have one/can use it. The alternative is a 48" mill which, with a 46" bar will just about clear, although you might need to knock off a bit of bark here and there. Either way, to mill this you need over 100cc. You could do it with an 070, 076, 084, 088 (880) or 090. I would only bother with the smaller top sections if they grew pretty much vertically - otherwise there will be a lot of reaction wood in them. That said, if you are making the owners a rustic type picnic bench then these would be ideal for making the legs and seat boards from, as it doesn't matter if they move around a bit and it will save more of the better grade timber for larger boards. The longer, straighter ones (e.g. Section 2 if it's straight) could be used to make 6"x6" or 8"x8" gateposts. As to what to make - it depends on who is selling it and for what. With an Alaskan, I wouldn't bother with less than 2" or you will be making a lot of sawdust. You could mill at 2" which will plane up for tables, 2.5" which, if removed to someone with a bandsaw and rapidly re-sawn to half thickness will make 1" finished size floorboards. You could mill some 3" slabs too. I wouldn't bother with thicker than this unless you are making a beam, and I would only do this if I knew someone who wanted the exact size I was making, otherwise the risk is that you make the wrong section relative to length for building regs. As your first go at milling, I wouldn't try quartering it, just go through and through. Also bear in mind that there is a lot of work here and to make the best use of the tree is an art. Just because you don't need a ticket for milling doesn't mean there isn't a lot to learn and the difference between good and bad is both in yield and quality. A good miller will charge more but this will be more than paid for in extra timber. One option would be to get someone in and work with them to see how it's done. Whereabouts are you? Alec

It won't be chain oil in the casing, otherwise it would be the down stroke that was difficult and taking the plug out wouldn't help. I wonder whether it is mix having leaked past from the crankcase into the top end, which is a risk with the horizontal design. If so, pouring a bit of neat petrol down the plug hole, swilling around and tipping out should clear it out. If you let it evaporate off for 10mins or so afterwards then it should be clear. I had something similar once - after quite a few pulls the problem went away and I never did figure out what the problem had been as the saw was then stolen. If you pull it over really hard, as in grab the handle and go for it, can you get it to pull over or does it just try to wrench your arm off? If you can do it, that's how I started mine in the end and once it was running it was fine from then on. Yes there is a tapped hole for a decompression button. If you look in the end of the barrel where the plug goes you will see three holes. One will have a bolt head showing, which is what can be taken out and a button fitted. It is interchangeable with the one for the 051. Alec

I hadn't viewed this thread since TVI's original comments on his kiln. There are some materials questions which have come up where I can offer some thoughts. There are several different failure mechanisms here, the key ones being creep, corrosion and differential thermal stress. Ideally you would use a thin section so the more corrosion and creep resistant it is, the better as you can then afford to go thinner. Thermal conductivity is also important since it will lead to better efficiency. Creep is the simplest. This is a temperature/service stress related mechanism. Stress here is minimal (it isn't a pressure vessel) so the ultimate service temperature probably applies. For continuous service, mild steel only takes 425degC (540degC excursions) so is not strong enough, whereas 316 stainless steel takes 815degC. Even this isn't high enough for the hot side, so higher strength materials such as 9% chromium steels with molybdenum and other alloying additions, as used in state of the art high pressure steam piping at 650degC might be better. Corrosion here is not straightforward. The inside of the retort is a reducing atmosphere. The outside could be anywhere from moderately oxidising to moderately reducing, depending on the fuel/air mix. This is fairly benign, so a highly oxidation resistant alloy would not be needed. The outer wall of the firebox is the most oxidising part of the system. Loss of section would therefore probably be fairly low even in an unalloyed steel (as evidenced by the reasonable service life in mild steel ring kilns) but a higher alloy would increase durability. However, there will be some acidic corrosion between firings, due to byproducts from the wood. This suggests a corrosion resistant surface would be useful, potentially coated. The environment is fairly similar to a bio-fired power station so thermally sprayed corrosion resistant coatings over a high alloy steel may be suitable, or alternatively the use of an iron/chromium/aluminium alloy may be an option as it also gives very good high temperature strength. Differential thermal expansion is the hardest to overcome. As the material heats up, it expands. If one part is heated more than another, the expansion causes stress which usually results in distortion of both the heated and unheated part. When it cools down, it doesn't go back to the original shape. These stresses can be enormous - we have looked at heat exchanger designs which can literally blow themselves apart with an internal temperature differential as low as 100degC. How much is determined by its coefficient of thermal expansion (CTE). Different materials will expand to different extents; the higher the CTE, the greater the expansion. This depends on the internal microstructure of the material - mild steel and other alloy steels are ferritic with a CTE of 12, whereas ordinary stainless steels are austenitic with a CTE of 17, which makes the problem worse. Coincidentally, most ceramics, including brick and concrete, have a much lower CTE (between 4 and 10) which is why they don't blow themselves apart in kilns. Overcoming differential thermal expansion is a combination of material selection and design. If you heat a kiln such as the Exeter from below you will get significant temperature differences between the top and bottom of the retort. More even heating, and design of supports to enable movement could help. The Hookway retort has a lot going for it in terms of minimising the above effects, although I am not sure whether this is by luck or design. The upright design makes heating around the structure more uniform; heating through the centre means the hoop stresses are minimised as the hottest 'tube' is the smallest diameter, and the use of a single heated tube means only one part needs to be made of a material with good high temperature strength - the outer wall can probably be mild steel as it won't typically exceed its stress limits, potentially with a high temperature coating to limit corrosion. I'm not sure how well it would scale up on diameter, but some Masters students at Sheffield did some thermal modelling on a horizontal version to increase efficiency. This should also make it modular, to allow heat from one unit to initiate the next. I have spotted some suitable tube which I am trying to scrounge and I then intend to give it a go. Alec

You haven't said how big it is. For the furniture to look in proportion the thickness and area should tie up. Rob D has posted a very good 'how to' for picnic benches made from 3" slabs but if it's smaller then scaling down to 2" will look better. You say it's for outdoor use. Be aware that a lot of the attraction of yew is the colour and the contrast between sapwood and heartwood, but the colour will quickly go and the sapwood isn't durable, so indoor furniture is a better bet if these matter. Alec