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Milling GUM tree`s

Started by symamania, June 14, 2015, 09:42:40 AM

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symamania

Hey lads,

Quick question I`ve got quite a few big gum tree logs lying around and I`m wondering if they would be any good for milling. I have been told there is a trick to doing this as the woods really prone to spliting and cracking? once cut into boards.

I guess it`s good for practice if its no good for keeping

POSTON WIDEHEAD

I sell Sweet Gum for barn siding. I have customer's who love this wood for their barns.
I have also used Sweet Gum for siding on my sheds.
However, the way I preplan is to let my customers know I have Gum and when they are ready, I will saw it and have it ready to pick up.
By doing this, they pick it up and install it on their sheds within a reasonable time before it starts twisting.
When I use it, I will saw what I can instal in a weekend.
I DO NOT saw, stack and sticker Sweet Gum. We have so much of this species that I don't want need to.
I love the Sweet Gum and recommend putting it up green with screws or ring-shank nails.

I believe the reason Gum trees took a big hit back in time is the fact that you can't split it for firewood. So everyone grew to hate it. But it is my 1st choice for siding.  :)
The older I get I wish my body could Re-Gen.

WDH

What kind of GUM are you referring to?
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

pineywoods

Sweet gum saws nicely. If you quarter saw it, makes nice lumber. Stack and sticker with plenty of weight, it air dries just fine. I have made furniture with it, takes a stain nicely. It even makes decent firewood IF you don't try to split it like you split oak. split 2 inch thick slabs off the sides of the round. Downside, unless kept dry, it rots quickly. Spalted sweetgum is beautiful.
1995 Wood Mizer LT 40, Liquid cooled kawasaki,homebuilt hydraulics. Homebuilt solar dry kiln.  Woodmaster 718 planner, Kubota M4700 with homemade forks and winch, stihl  028, 029, Ms390
100k bd ft club.Charter member of The Grumpy old Men

Magicman

symamania has not updated his profile with his location, but I doubt that there is Sweetgum in Western Australia.   :D
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Ianab

Quote from: Magicman on June 14, 2015, 04:19:47 PM
symamania has not updated his profile with his location, but I doubt that there is Sweetgum in Western Australia.   :D

That was my thought too. Admin lets me see he's in Australia, so his "Gum" will be Eucalyptus. That narrows things down to about 100 different species.

The ones I've sawn have been a mixed bag. Other members will have had more experience with the various species and how to best deal with them
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

GeneWengert-WoodDoc

In the U.S. We have sweetgum.  The wood is sometimes called sap gum if it is sapwood.  The heartwood is called red gum.  Then we have black gum, tupelo gum and black tupelo (all the same) that are not related to sweetgum.  So, when someone says they have "gum logs," it is important to get more info on what they have.  If sweetgum, warp is the big issue, not checking.

In Australia, Africa and other countries, they have gum trees that are eucalypt, but some gums are not.  In fact, remember the song which comes from Australia?  This gum tree is not sweetgum.

Kookaburra sits in the old gum tree
Eating all the gumdrops he can see
Stop, Kookaburra, Stop, Kookaburra
Leave some there for me.

Kookaburra sits in the old gum tree,
Counting all the monkeys he can see
Stop, Kookaburra, Stop, Kookaburra,
That's no monkey, that's me.

I worked in Qld, Australia with a wood they called blue gum.  It seemed easier to develop surface checks that got really deep easy with blue gum than with American oak.  Very slow, cool drying would be essential.  Of course, such drying does not control warp very well, so close stickers, perfect alignment, and top weights would be a good idea.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

longtime lurker

Saying "Gum tree" in Australia can cover a whole lot of species within the family Myrtaceae, subfamily Leptospermoideae, and a few others of similar appearance as well. Generally here "gum tree" can refer to any member of the Genus Ecalyptus, Corymbia or Angophora... and indeed there is still ongoing discussion as to what species falls where in a lot of cases.

Even saying "Blue Gum" is confusing. There are three of those - Sydney Blue Gum ( E. saligna), Queensland Blue Gum (E. teriticornis), and Southern Blue Gum ( E. globulus), all of which are commercial species and all of which have widely varying properties. Then you have local naming/ mis naming which might actually mean that "Blue Gum" might mean any tree which has a big straight blue grey bole and falcate leaves and looks like it deserves the name blue gum to a casual observer.

They are basicly endemic to Australia, New Zealand, New Guinea and several islands of the south west pacific, but there have been plantings world wide of a number of species. Notable plantation areas are located in South Africa, France, Spain, Portugal, Argentina, Brazil, Israel and China to name but a few. In the USA for instance if you go to SoCal it seems every second tree is a gum tree. E. globulus is there to stay...


In 'straya "gum tree" has about as much meaning as he word "pine" does in terms of species description.

General advice would be to seal the ends immediately after felling, mill as soon as you can, be aware that your cut pattern may need to allow for significant log movement, be aware that there may be significant shrinkage and subsequent collapse, don't let the sun get at the sawn timber till its below 20% moisture, use it green to frame with and strip it out with great care if you want it to dry.

I don't know a lot about the West Australian species but I have a pretty fair reference library and if you can determine what species it is then I can quite likely give you a fair bit of detail about its milling characteristics.
The quickest way to make a million dollars with a sawmill is to start with two million.

WDH

I suspected that that (Tom RIP) GUM was an Eucalypt. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

symamania

sorry lads for the vague description yep I`m in Western Australia so not to many liquidamber`s growing around me. I`m pretty sure these are the "gums" Corymbia citriodora, Corymbia maculata. Not great with my Eucalyptus I.D or many other Australian trees

but do also have alot of sheok and jarrah trees (euca Marginata) around

symamania

cheers for the info lurker great detail

JustinW_NZ

Quote from: symamania on June 14, 2015, 09:47:56 PM
cheers for the info lurker great detail

Yip that was a good wrap up!

Many of the euc's are grown here in NZ, we mostly mill them as they are a good market for those willing to take there time.

Basically every log is full of stress so learning how to release the tension wood off the saw is good.

Cheers
Justin
Gear I run;
Woodmizer LT40 Super, Treefarmer C4D, 10ton wheel loader.

longtime lurker

Right so with the species you've mentioned your about to get a full course in why Gum tree naming is so problematic.
Corymbia maculata is "Spotted Gum"
Corymbia citriodora includes two subspecies and is also "Spotted Gum"
... and theres another "Spotted Gum" species as well in Eucalyptus Henryi.

Confusing huh? So here goes. Spotted gum is the most important hardwood species in Qld. But that includes both the above Corymbias, which grow in geographiclly diverse areas. Theres also some crossover in the range of the two citriodora subspecies. None of which has much to do with sawing characteristic or the wood properties anyway. For the sake of clarity here I'm going to henceforth refer to citriodora by its other common name of "Lemon Scented Gum".

Wood properties and general appearance of the lot is all similar.  Mid to chocolate brown in colour with a wide band of white sapwood. Class 1 hardwood above ground with a lifespan of not less then 40 years in untreated heartwood, class 2 in the ground so treat it if its going there and you're putting your house on top of it, but don't fret it if its only a chookhouse. Lyctid susceptible, termite resistant, Air dry density of around about 950kg to the cube at 10% moisture (5lb to the board foot for you non metric types) Janka hardness is about 8kn wet and 11 dry - all of which is a complicated way of saying thats its both hard and heavy, though not that tough by Australian standards.
Tangental shrinkage is about 6% and 4.5% radial so just cut it to nominal and let it dry in service for framing, or dry for flooring. Strucurally it'll grade F22 green and F34 seasoned based on clear specimens, so to come back to regular F14 span table sizes for green timber you can have a hole 1/3 the width of your board and still put it into service if no-one is ever going to see it..

You really don't want dry framing in this stuff unless you're a masochist and feel like predrilling every nail hole in your house. You can basicly do anything with it in terms of heavy construction members, general framing, decking and flooring and its the main Australian species for impact resistant tool handles so you can make your hammer handle from it as well.

On to milling: I've cut Lemon Scented Gum before and it cuts well. It's firm but not hard and not too tough on the gear.  You get sawdust rather then powder and the mills not whining and shaking when shes two foot deep in a cut. The wide sapwood belt can be a bit of a pain in terms of it requiring treatment for lyctids but if you're just banging out a few boards for own use just ditch the sapwood and cut another tree. It does tend to vein out a bit on poorer soil types but mostly its pretty good.
My experience is that it lays pretty flat during sawing with not a lot of bow or spring in smaller logs up to say 18-24 inches in diameter. Bigger logs though tend to pull a fair bit, which makes it the opposite of a lot of the eucs where small logs are generally difficult and bigun's are good.

I haven't cut C. maculata before but [member Sigidi] runs a sawmill on the stuff day in and day out and he might have some pointers there for you.

The quickest way to make a million dollars with a sawmill is to start with two million.

longtime lurker

The quickest way to make a million dollars with a sawmill is to start with two million.

woodyone.john

My experience is unless you know the trees are open grown,usually have large heads,if tight or forest grown[ long skinny trees with smaller limbs] I use the formula of small end diameter times 600 millimeters to give a length that wont 'spring' to much. I have sawn lots of saligna ,botryiodes ,globoidea and pilularis hand fulls of other and some I never did get to identify.As most of what I've sawn is for flooring ,its mostly quarter cut,and with to much spring recoverys head south real quick. squareing the sap off prior to canting take a lot of tension [not all]out
cheers john
Saw millers are just carpenters with bigger bits of wood

symamania

*DanG some great info mate, I always have trouble I.D Australian trees

Cant wait to get my mill and have a go

JustinW_NZ

Quote from: symamania on June 15, 2015, 07:42:32 AM
*DanG some great info mate, I always have trouble I.D Australian trees

Cant wait to get my mill and have a go

They are fun to mill!!

The seeds are the best way to ID, get a book or search, im building up a little file with pictures of leaves (adult and juvenile) and the seed pods.
Easiest way to tell them apart.

Cheers
Justin
Gear I run;
Woodmizer LT40 Super, Treefarmer C4D, 10ton wheel loader.

sigidi

Yeah, I've had the pleasure of cutting lemon scented a few times, but cut a DanG sight more C. Maculata. Dropped 44 cube of it over the queens birthday long weekend, a fortnight ago and we've gone through about half of it in 4 days milling.

I agree with a lot of lurkers info, only I've found small long logs pull like hades, nice and stable in the log size we go through, cuts like a dream green - we're going through about 5 cube a day and only need to sharpen the Lucas at the start of the day - we cut a mix of 4*1, 4*3 and 10*2 using logs 400SED and up to 4.8m Leong
Always willing to help - Allan

soutz

As to she oak. beautifyl but dense and prone to move. we do them in slabs 50mm thick and sticker them. some will move and some wont . they make for  amazing table tops, and there is a market for weapons makers

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