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Re: Chainsaws:


Gluestick
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Useful info kim.

However, I purchased a Mitox from the people I mentioned earlier (The Greenreaper): and I must say I am very impressed with their technical knowledge, stock and spares back-up. Mitox products come with a Two Year warranty: and full spares resources. 49.5 c.c., 20" blade brand new £189 inc VAT: fresh stock: it was Drop Shiped from the UK Concessionares, Rochfords garden products, who have been in business since 1978.

The Mitox is in fact a made under license duplicate of an obsolete leading manufacturer's saw (I suspect Stihl): as with so much, made in the Far East. What isn't? It is very well made and finished and uses Oregon chains and blades

I am personally pathologically biased against ANY Electrolux group product now, due to their nice habit of failing to support anything except current models with after sales spares, technical support etc: and insofar as agricultural equipment be concerned, Electrolux have hoovered up all the leading brands: including AYP, Jonsared, Stihl, Husquvarna, McCullough, Flymo, keep on going.

For my Poulan Weedeater and one of my Rallye ride-on tondeuse I have had to resort to importing spares from the USA.

Electrolux were supremely indifferent.....................

 

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[quote user="Gluestick"]

I am personally pathologically biased against ANY Electrolux group product now, due to their nice habit of failing to support anything except current models with after sales spares, technical support etc: and insofar as agricultural equipment be concerned, Electrolux have hoovered up all the leading brands: including AYP, Jonsared, Stihl,

[/quote]

That explains the post describing cheap plastic parts being used on Stihl machines now [:(]

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Their corporate strategy, T, seems to be to buy leading brands with solid histories of excellence behind them and thereafter cheapen the manufacturing process.

Previously we had a number of superb Bosch (German manufactured) products: when it became time for a new washing machine, the sales manager of our local excellent supplier told me Bosch was now buying in from Electrolux and the white goods all made in Turkey!

So we switched our allegience to Siemans: OK a tad dearer but a superb German made product: no complaints whatsoever.

The one ray of sunshine for agricultural/gardening/arborial kit is the rapid growth of decent products emerging from China and India. At demon prices, too.

OK some are utter junk, such as Ryobi: but they will improve as they gain market share.

So much stuff now is made in China and re-badged anyway, buying a "Top Brand" fails to make much sense to me right now.

 

 

 

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I will probably be considered unworthy to write here, but I am delighted with the 'Best Green' electric chainsaw I bought from the Bricomarche last year. I needed to cut up a silver birch that had come down in our garden, and did not want to invest in a serious saw.

For 35 Euros the saw came with an Oregon bar and chain and so far I have not had to sharpen it. The tree I cut up was around 16" diameter at the base. I must say I am impressed with the cheap saw, although I would not dream of mentioning it in the pub back in Sussex!
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Not unworthy at all Etoile: if something works well, then my personal philosophy is the brand name and the price are fairly inconsequential.

In  similar vein, I bought a little electric crocodile mains saw from Aldi (UK) last year; from memory on extra special offer is was less than £15: and Mrs Gluey loves it for general gardening jobs in UK and France, as it's light enough for her to use comfortably: and at 600 watts, powerful enough to chop through tough "Green" shrub branches.

And I have found it extremely useful for chopping off such as PVC gutter pipe, soil pipe and various carpentry jobs when space has been very limited. Came with four different blades too.

If it works.........................

 

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"Bestgreen" what think tank of cretins make up these anglicised names?

I am currently trying and failing to repair a Bestgreen debroussailleuse for a friend, I found the carburation fault but then managed to break the offending part when trying (and failing) to repair it.

My (French) friend will now have to put Brico-Marché's after sales service to the test, he originally thought it would be easier and cheaper for me to buy the parts for what he thought was a British machine in the UK, he was disappointed when I told him that no-one in their right mind would call a company or its products Bestgreen [6]

Of course it would be nice if I were to be proved wrong once again as I dont hold out much hope with Brico-Marché.

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I feel in all probability, JRC, the orginal name was "Bestgleen".

There are skads of cheap agri-machines flooding onto the European market from China with names including Star, Tallon. keep on going.

And JCB have joined the NuTool, Draper et al fray with their own badged generics.

Walbro carbs are used by most reputable manufacturers: albeit now made under license in Japan.

Ready availability of spares is what I always now check before buying anything.

And that is, perversely and interesting reality about the States: we always think of America as the home of "Planned Obsolescence": whereas in point of fact, they enjoy a huge aftermarket for pattern spares for all US manufactured tools. And whitegoods.

The service kit for my Poulan Weedeater (Originally sold in France and no spares available, yet it's not that old - US manufactured Walbro carb) included every necessary component: diaphragms, needle jet complete with level arm; even down to a new Welch plug! New Feed and Return fuel pipes; fuel filter, gaskets.

All pattern.

 

 

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I understand your thinking but the longer the bar and chain the more friction ( even with oil) there is to overcome betwwen bar and chain and within the rivets of the chain and the chain will try to slow down as soon as it leaves the sprocket therefor the more power is lost. The more the chain heats through friction the faster the teeth wear down thus the shorter chain cuts faster and lasts longer.

If you are cutting professionally (30 years in the Forestry Commission) you use the highest practical power output with the shortest cuidebar/chain combination for the tree sizes you are felling.

Cheers

Grumpy

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I would have thought that the shorter chain with less cutting teeth would mean each tooth would be used more frequently and the cutting tooth friction as it cuts through the wood will produce a lot more heat than the guide links running in the guide groove and round a sprocket (all lubricated)

I don't doubt your thirty years service but where did the information come from, the chain sellers?

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I do love industry/activity lore, used to counter established engineering and scientific absolute!

Chain Friction: when tuning standard production engines for competition purposes, one of the first ports of call was always to employ a Duplex Chain.

This was particularly critical for BMC A Series engines. Power loss due to friction was as might be expected a core focus of the tuner.

Using your lore, Grumpy, by adopting a Duplex Roller Chain, then the friction caused by rivets and the chain passing over duplex sprockets would have created considerable power loss; I can assure you it did not: and does not.

The main point of friction for a chainsaw chain and blade in good condition assuming drive and idler sprockets are in good condition and all is well lubricated, would be simply the portion of chain being forced into the blade groove by the cut: and obviously, the frictional resistance of the material being cut against the cutting teeth.

Once again, if one considers the matter logically, the chain speed over the blade, unloaded, is simply a function of engine revolutions and the size of the drive sprocket. Static friction generated by the drive mechanism and the chain are very low: which is why one can rotate the chain by hand when sharpening in situ.

I defy anyone, except Superman, to rotate a small four cylinder IC engine (Bare- Undressed, with plugs removed) by hand alone, without some sort of lever. Now that is friction (Ends, mains, piston rings, small end, oil pump, valve gear etc).

 

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Hmm Hyvo chains are roller to sprocket whereas chainsaw chains simply run the back of the link along the bar as well as the rollers so not sure it's a fair comparison. Also with the engine analogy try removing the valves....you will find the bottom pulley turns reasonably easy by hand when you aren't trying to compress valve springs! Granted the metal to metal interface of piston rings on bore is very similar to that in the chainsaw bar therefore I would suggest a small 6 cylinder engine would be correspondingly more difficult to turn over by hand that a similarly sized 4 pot both with valves removed........

What was this about again...Oh yes,,,short -vs- long bars......no discernible difference as the friction imposed by the work will far overcome the friction in the bar and arguably a well adjusted chain will be guided by the bar rather than be tightened into it.

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OK: agree about the valves Mac: let's therefore think in terms of a block assembly only: no head.

I defy anyone to rotate the crankshaft on a just assembled block assembly with new pistons and rings and mains and ends! Even without the camshaft in and the timing chain etc therefore not in place either.

Normally, the inertial friction is awesome!

Might be possible if the bores were shot, the pistons oval and the rings collapsed and the ends and mains non existant![:D]

Anyway, back to the core concept.

Now, the only useful info I can find as the nub interests me is on the Home Depot site: for Canada. Guess they know a bit about trees there..........

"Bar Length

Bar length refers to the length of a chainsaw's cutting saw. This can be as small as 8" or as large as 42". Generally the higher the bar length the more efficient it will be at cutting through wood. A chainsaw can safely cut through wood twice the size of its bar length. Therefore, a chainsaw with a 20" bar length should easily cut through a piece of wood no greater than 40" in diameter. However, keep in mind that the greater the chainsaw's bar length, the more difficult it may be for you to manage and hold while cutting."

Webref:

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Stands to reason and also the longer bar should provide more cooling than a shorter bar because of the ratio of bar to wood and thermal conductivity of steel vs wood.

I am sure the manufacturers have worked out the ratio of cutting links to guide links to provide the best all round performance.

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The last place i would ake info. from is the manufacturer.  This info came fron a mix of time and motion, training  experienced workers and our mechanical engineers.

With the shorter chain the chain moves faster and has greater cooling thus lowering the wear.

Grumpy

(thinks, "how long can we keep this thread going Eccles")

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A short or long chain will move at the same velocity which is governed by the engine revolutions and the sprocket diameter.

Big Macs second paragraph makes the most sense, the friction on the bar regardless of its length is de minimus with respect to the power dissipated whilst cutting the wood.

Gluestick you challenged anyone to turn over a cylinder block without a lever?

Thats was exactly what I did whilst building race engines, with the short block built - crank, rods, pistons, cam and timing chain (duplex) if I could not turn it by hand on the crank pulley (and I used to run 3.5" pulleys) then I would strip it down and start again bluing and scraping the bearing surfaces if necessary.

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Grumpy, do you mean the shorter bar chain combo means the machine revs higher?

The faster the cut the more heat is produced and if there are less teeth the more work each tooth must do surely which in turn means more heat in the cutting links which if they overheat will reduce the temper of the steel which would lead to higher wear. As I said above the longer steel bar would help conduct heat away from the cutting area and more teeth means less work per tooth although the machine may not rev as high so the cut may be slower the blade will last longer. Did time and motion add in the time taken to change a dull chain for a fresh one and the cost?

 

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[quote user="Chancer"]

A short or long chain willGluestick you challenged anyone to turn over a cylinder block without a lever?

Thats was exactly what I did whilst building race engines, with the short block built - crank, rods, pistons, cam and timing chain (duplex) if I could not turn it by hand on the crank pulley (and I used to run 3.5" pulleys) then I would strip it down and start again bluing and scraping the bearing surfaces if necessary.

[/quote]

Scraping Recticular Tin Thin Wall bearings, JRC?

Most adventurous........

I still have all my scrapers used for scraping in and sizing Babbit bearings: but I would not dream of scraping RT shells: if in the Dry Build they showed  significant irregularity: then they went back to the supplier.

And whilst we did of course, carefully gap rings, a new bore and forged Mahle pistons would naturally present with initial friction: even three ring slipper pistons in such as MAE, FVA etc.

Most of our (Ford & Lotus) blocks were dry-linered: and after boring and honing still required some initial settling down: which was why serious stuff was always run-in on synthetic oil and thereafter Power Tested and set up on an engine dyno (Often Titan's in Huntingdonshire).

Interestingly, most MAE Cosworth (Screamer F3 engine) lumps were the very devil to start from cold, as the piston and ring tolerance once bedded were so loose, they failed to suck adequately! So we invariably resorted to the old dodge of cold plugs and a squirt of SAE 30 into the bores: and 24 volts!

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[quote user="Gluestick"][quote user="Chancer"]

[/quote]

Scraping Recticular Tin Thin Wall bearings, JRC?

Most adventurous........

[/quote]

Yes you have called my bluff there [;-)]

Also it was only the bare crank assembly that I would verify by hand turning, with the pistons it would need a tweak with a spanner to brake the stiction.

There used to be an old school engineer that did rebores and crank grinding just behind my house, someone that not only understood tolerances but knew what he could and could not work to, by putting our heads together I could specify the rebore and crank grinding and honing tolerances, I would then do my own finish honing with some American flexi hones, most others including the manufacturers always overbored knowing that the customer was unlikely to properly run the engine in.

 

I used to run mine in for an hour on a chassis dyno lubricated by a mixture of oil and parrafin and one could actually see the BHP climb and the smoking reduce to next to nothing, sometimes we had to accelerate the process by judiciously adding Vim via the intake trumpets.

Many of my milder tuned engines built in this way could be started by hand turning to a tad BTDC and turning the dizzy to open the points or swiping the battery terminal even after being left overnight, just as they used to in the olden days when engines were properly built by the manufacturers

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[quote user="Chancer"]

Many of my milder tuned engines built in this way could be started by hand turning to a tad BTDC and turning the dizzy to open the points or swiping the battery terminal even after being left overnight, just as they used to in the olden days when engines were properly built by the manufacturers

[/quote]

Ah: shades of such as the Leyland of 1920s vintage: so my old Dad (A car and racing nut) told me, one could start these by the simple expedient of turning on the ignition switch!

However and of course, they enjoyed heavy and deep cast iron pistons.

The wonders of oversquare engines and silicon alloy cast pistons and less reciprocating weight had yet to be really considered: apart from one Etoire Bugatti, naturally.

[:)]

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