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Sunday, 19 November 2017

Huztl Farmertec 036 chainsaw kit review

The Huztl 036 after 10 hours hard work (with home-shortened bar)
We recently made an 036 chainsaw from a Huztl/Farmertec kit of non-genuine parts. It was fun and educational, and so far the saw is working well. Overall I think these kits are a great product for someone who wants to develop their mechanical skills and get a good chainsaw, at a low cost, that they know how to repair.

Choosing a saw

Recently, I was looking for a smaller chainsaw to use in thinning the forest on my in-laws’ place at Stanthorpe. 100 years of neglect has produced a forest which is dangerously overcrowded, mostly with black cypress, but also with small eucalypts, amongst the well-spaced old eucalypts. In its current form, the forest is fully set up for uncontrollable, crowning wildfires that would kill many of the old trees. Lots of it is now too thick to safely or productively carry a controlled fire, and it appears that manual thinning is necessary to produce a forest structure which can carry a cool fire, preserve the old trees and achieve maximum restoration of  the historic Aboriginal woodland.
The worst sort of cypress thicket, ready to burn to the canopy - or be thinned
When thinning this forest, most cutting is the small (mostly up to 100mm diameter) cypresses, which cut easily with smaller saws like a Stihl 025 or 026. However the stringybarks and the sandy country are very hard on chains and bars, especially the dead stems with very strong, dry, bark fibres and sand in and under the bark from ants. 
I find that bigger chain pitches work better in dirty wood: somehow the bigger teeth seem to get under the dirt and keep cutting even if a little blunt. A bigger chain and a stronger motor also makes it quick to prune the cypress branches, chopping the smaller branches off without having to stop and saw through. A Stihl 036 (62cc) with a short bar was looking attractive: only slightly heavier than an 026, but carrying 3/8” chain and a stronger engine which can work lazier and last longer. The 036 has some other desirable characteristics as well.

Repairable chainsaws

If you want a saw that can do a lot of work and last a long time, and you want to do your own mechanics, it’s important to know that some saws are more repairable and durable than others.
Some brands of saw are easier to get parts for, as well as being good quality. In Australia, Stihls are clearly the easiest to get parts for, including non-genuine parts. Husqvarna would be the second easiest, and appears to be Stihl’s main competitor for quality. In Australia, Stihl has a near-monopoly in chainsaws, with other makes being pretty unusual, with the exception of consumer saws in hardware shops, which tend not to have much spare parts availability or range of sizes, as well as most being of poor quality. My experience has been mostly in Stihl, so I prefer to stick with them.
Stihl chainsaws come in 2 distinct qualities, which are very different in repairability.
The older design type of saws, often described as “professional” saws, have a metal chassis which forms the structure of the saw. It comes in 2 cast magnesium halves with a vertical joint, sealed with a gasket, forming the oil tank and the crankcase, and having moulded flanges to carry the external parts of the saw. The cylinder bolts on top of this crankcase and is easily removed or replaced, without necessarily dismantling much of the saw. A worn or damaged piston and/or cylinder can be quickly and cheaply replaced. These saws are highly repairable and, unless they have serious accidents, can have almost indefinite life expectancies. When I first bought Stihl chainsaws, this was the only type of saw they sold. However it seems that market pressure pushed Stihl to produce another line of cheaper, less repairable saws for less intense use. The professional saws are still made and sold, at significantly higher price.
This is a typical metal chassis from a Stihl professional saw (in this case a Stihl 034), viewed from the flywheel side (see tapered crankshaft with keyway). Oil tank is on left, piston is on top (cylinder is removed). 
The same 034 from clutch side, bar studs on right. This saw is old and in poor condition, but quite repairable with non-genuine parts. Worst damage is corrosion around clutch, perhaps from corrosive palm tree sawdust.
The newer “consumer” design of Stihl has a plastic body that wraps around a more self-contained metal engine. The cylinder and the top half of the crankcase are a single metal barrel, and a metal pan is bolted on the bottom to close the crankcase. Removal or replacement of the cylinder involves a major dismantling of the saw, to extract the motor from within the plastic body.
This is the type of engine in "consumer" saws, which is bolted into a plastic body (I think this is for a Stihl 029)

The 2 different types of Stihl chainsaw can be generally identified by their model numbers, using a sort of Stihl numerology. In the old model numbers starting with a zero (mostly from the 1990s, when the modern designs started), the even numbers (e.g. 026, 036, 046) were the professional saws. The later odd numbered models (e.g. 017, 025, 039) were the plastic bodied consumer saws. With the new model numbers starting with “MS” (when for example the 026 was renamed the MS260), most of the professional saws now have an even number as the middle digit (e.g. MS381, MS461) and the consumer saws have an odd digit in the middle (e.g. MS170, MS250). This is not quite a perfect system, e.g. MS180 is a consumer saw.
For me, wanting a saw with an engine about 60cc, there are 3 Stihl options: the old 036 professional saw (no longer sold new, but available second hand or as a non-genuine kit), the MS361 which is a more modern and complex professional saw, or the MS391 which is the similar-sized consumer saw. My preference was for the 036, as it is a simpler design than the MS361, and more durable and repairable than the MS391.

Huztl non-genuine kits

Through watching youtube videos about chainsaw repair, I discovered the recently emerged option of buying a kit of “Complete repair parts”: a full set of non-genuine chainsaw parts, which can be built into a working chainsaw. The principle source of these kits is www.huztl.net (a name appparently made from “Husqvarna” and “Stihl”), who sell a huge range of non-genuine parts, mostly branded as “Farmertec”.
For anyone repairing their own chainsaws (or brushcutters etc.), the Huztl web shop is astonishing in its scope and its prices. The accessibility alone is revolutionary: Stihl parts are difficult to find without walking into a genuine Stihl dealer’s shop – you can’t browse or price parts online. The Huztl site has huge catalogues of parts listed with photos, viewable by chainsaw model.
The quality of parts sold by Huztl will take some time to discover. Some parts are clearly fine because they work from new, e.g. clutch covers, carburettors, bolts. Some will be quick to evaluate: chains, bars. Some, however, will take some time to be confident in: pistons, cylinders, crankshafts, bearings, seals. If the quality of Huztl parts is good enough (and I am so far happy), it offers a great resource to backyard chainsaw mechanics. The question of quality and durability is fundamental to my writing this entry, so I will try to report as well as I can on my experiences over time.

Ordering the 036 kit

The Huztl 036 kit is astonishingly cheap: mine cost about AU$300 delivered, plus bar and chain for another ~$25 (a new Stihl MS361 is listed at about AU$1600). I made the mistake of ordering parts for other chainsaws, along with the 036 kit, which meant we had some troubles working out what was what – most parts are not labelled. The kit does not include bar or chain, so I ordered these as well from Huztl. Currently the shortest 3/8” bar they sell is 18”, which is longer than I want, so I made a project of cutting an 18” bar from Huztl down to about 14”, see my post on this here.
I ordered a couple T-handled T27 tools with my kit. This is the main tool needed for tightening bolts. I also bought a Huztl crankcase splitter tool, in case we made a mistake and needed to open the crankcase. I bought a flywheel puller (2 in 1) tool, to make it easier to remove the flywheel in case of crankshaft seal trouble.
I also ordered some extra gaskets for the crankcase and cylinder, and some spare crankshaft seals. These seemed at significant risk of damage during assembly - we did need to replace one crankshaft seal we damaged while assembling the crankcase.

Assembling the 036 kit

Unboxing the parts on the kitchen table
Nearly all the assembly was done by our son Jasper, who couldn’t keep his hands off it. There are no instructions at all, and almost no labels on the parts. Luckily our neighbour and friend had a Stihl 036 we could borrow to look at and to exchange parts. Most importantly there is a rich resource of youtube videos specifically on how to assemble these kits.
Here are the videos we found most useful:
Afleetcommand’s 036 assembly series
Part 1:

Part 2:
Matthew Olson’s “bolt by bolt” 036 assembly series:
There were some other youtube videos on assembling the crankcase which were helpful, mostly found by searching for Huztl. As, well, I liked Andy Reynolds’ chainsaw repair series on youtube, which share some of his accumulated experience with chainsaw maintenance.
For most of these saw kits, construction begins with assembling the crankcase. For us, this was the only difficult bit. We used our wood-burning cooking stove to heat the 2 shells, and used a wooden mallet from our woodwork shop to make adjustments. We damaged a crankcase seal on the clutch side, but it wasn’t difficult to replace (for crankcase seal replacement see https://www.youtube.com/watch?v=znC1HfkCzC8&t=8s). With heat, patience, and a wooden mallet, it isn’t too hard.
036 coming together on the kitchen table
Once the crankcase is assembled, it’s just a matter of bolting everything else together.
The Huztl 036 - without an 036 label on the flywheel cover - otherwise looks just like any other 036

Carby troubles

Once assembled, I filled the fuel and oil, and adjusted the carby jet screws to 1 turn from closed (the standard startup setting). I was able to start the saw and run it at high revs, but I couldn’t get it to idle. There was clearly a problem with low speed mixture: adjusting the low-speed jet seemed to make no difference. After doing a crankcase pressure/vacuum test to see if we had damaged a gasket or crankshaft seal, I tried swapping carbies with our neighbour’s genuine Stihl 036. With a genuine carby the saw worked perfectly.
Huztl promptly sent a replacement carby once I sent photos of the non-working part. The new carby worked perfectly.
During the first few hours of use, I found the idle speed variable. Tilting the saw on its side would drop the idle speed and sometimes stall it. Again I worried about crankcase vacuum leaks (I’ve had some bad experiences…). I then realised that the idle speed ajustment screw wasn’t changing the idle speed. Looking closely, I could see that the throttle connection wire (from the plastic throttle finger lever to the carby) was a fraction too long, so the throttle butterfly lever wasn’t sitting on the idle ajustment screw. After I removed, slightly bent and re-installed the wire, idle speed was fully adjustable.

Using the Huztl 036

Once carby problems were sorted, the Huztl 036 worked like a brand new Stihl. Compared to other cheap chainsaws, it has the advantage of Stihl’s excellent design. The 036 is a really good saw for my work, lighter than the Stihl 038 and MS381 that we have used a lot over the last 20 years, but still powerful and having the 3/8 pitch chain advantages.
Once the saw was working, I attached a cheap digital hour meter. This adds up the run time, so I can add up the short runs that are usual for chainsaws.
Here's the digital hour meter on the cylinder cover. A wire from the meter wraps around the spark plug lead
So far it’s done 10 hours, which is actually a lot of chainsawing: several days in the forest. It’s been a mix of long, light work thinning cypress (soft wood, small diameters) and hard, continuous, full throttle cutting dead stringybarks into firewood blocks. Nothing has broken or failed, and I’m very happy with the saw.
The 036 working in the cypress thickets

Is the Huztl 036 any good?

So far, I’m very happy with the Huztl 036. It’s fair to say it’s seriously changed my understanding of chainsaws.
The first advantage is that we needed to put it together. My son and I learnt a lot from making it: once you put a machine together like that, it is never a complete mystery again. We know every part, and feel confident that we can deal with mechanical problems.
Easy, low cost access to a complete range of parts for these kit chainsaws, that appear to be of good-enough quality, is also pretty revolutionary for chainsaw users like me. It stops chainsaws being throw-away consumer goods when there is a breakage or failure – not necessarily because genuine parts aren’t available, but the cost of genuine parts and dealer labour is often too big a risk for an old saw which might have other problems. If a saw you made yourself wears out a piston and cylinder, and the parts cost AU$30 to replace and you have confidence to do it yourself; then that saw is likely to be repaired and work on. 
Remember that the low money cost of these parts is balanced by the need to be your own mechanic and do some quality control for yourself. It’s very different from stopping off at the Stihl dealer and picking up a new saw that is immediately ready for work. If you do buy these parts, be ready to take the time to check the parts, put things together carefully and if needed, to ask for replacements. 



Wednesday, 30 August 2017

Shortening a chainsaw bar

Shortening an 18” 3/8”pitch Huztl “Holzfforma” brand bar to 14”

Short bar on Huztl 036

Why shorten a chainsaw bar?

I like my chainsaws to have bars as short as practical. This has many advantages: a lighter unit to lift, gives the motor an easy life, less bar and chain to lubricate, more power for the teeth in the cut, quick sharpening, etc. (I go on more about the benefits of short bars in my electric chainsaw entry).
Given all this, I wanted a suitable bar for my newly assembled Huztl 036, intended for thinning and limbing small trees. In my experience, the 036 is suitable for no more than a 16” bar. It can comfortably pull 16” of 3/8” chain through lighter hardwood, but at 18” it is bogging down. When the Stihl 036 was relatively new (in the early 1990s), Stihl’s recommended bar lengths were 37cm (15”) and 40cm (16”) and I think they were right. The current Stihl catalogue shows the current version of this saw, the MS362, fitted with a 20" bar as standard. That's a toddler wearing daddy's boots...
So for my new saw, I wanted to try for 14” – a radically short bar for these days of bar length anxiety. Walking into a Stihl dealer was financially frightening, I couldn’t find a suitable bar online, and the shortest 3/8" pitch bar from Huztl was 18”. So I thought I’d try something I’ve been daydreaming about for some time: cutting a bar to a shorter length. I had a cheap 18" Holzfforma bar from Huztl, and was willing to risk it for science.

How I went about it

First step was to work out what length of chain to use, then to make the bar to fit. I looked at a 60 link chain on a 16” bar and rim sprocket:

I like Stihl’s practice of making bar lengths to fit chains with even numbers of teeth. This means that the alternating pattern of teeth continues around the whole loop. Given this, the next shorter length of chain was 4 links shorter, so I made a chain this length and tried it in place
The 56 link chain trying the bar for size
I used a genuine Stihl bar to mark out the pattern of slot and holes on the Holzfforma bar.

Using the Stihl bar to mark the slot and holes
Then I punched and drilled the bar.
Drilling the holes

cutting the slot with angle grinder with cutting disc, using a steel bar as guide
I did have an interesting challenge in this process. When centre punching one of the bar tensioner holes, there was a small bang, and I found myself with a splinter of steel surprisingly deep in my pinky finger, a punch with a flattened point and no mark left on the bar. By chance the tensioner holes aligned with spot welds from laminating the bar layers, which had left hardened patches of steel (spot welding brings spots of steel to melting temperature, and when the electrical resistance heat is suddenly stopped, the heated spots are quenched by the cold steel around, which will cause hardening in carbon steels). I first tried to deal with this by moving the hole a little, but ended up having to temper the steel with heat to make it drillable. Thus the tensioner holes are a little misaligned.
The bottom hole is right on the hard spot weld - see the failed punch mark

Cutting the slot between the holes
Filing the slot after grinding

Chamfering the hole edges

Chamfering the hole ends

Cutting the bar to length - there's no turning back now!

cutting off the corners

Grinding a curve onto the bar

Smoothing the bar shape on a linisher

Grinding the bar slot into the bar base

Chiselling a wafer of middle laminate so it can be ground away

Tempering the bar to enable drilling

Drilling the bar after tempering

Drilling the oil holes using the old bar base as template
The new bar fitted to the motor

Outcome

After all this, the bar fit on the chainsaw. I had to make some modifications to the newly ground slot at the bar base, to remove wafers of centre laminate I had missed when grinding the slot - the chain links were catching on a remnant.
The bar looks a little wider than normal at the base, but I can live with that
The saw cuts fine with the new shortened bar. It's currently only had a few minutes to test, but bar problems would normally show quickly: pinching in the groove, failing oil flow, tensioning problems etc..
The job took about an hour and was greatly extended by caution and newness. The most difficult part was grinding the chain link groove into the newly shaped bar base - it was very hard to see what I was doing.
I recall 25 or more years ago when I was doing a lot of chainsaw milling, my chainsaw shop had a machine to regrind the slot in hard nose bars. This had a grinding wheel the right thickness, held the right distance from a table, to reliably grind bar grooves. That would be very useful for this job.
If I shorten a bar again, these would be some tips to help:
  • Temper the steel at the bar base before drilling any holes
  • It would be really good to have a proper bar groove grinding setup
With these things in place, shortening bars would be relatively simple - which is good, because there are so many over-length bars around....

Update on the bar in action

So far, the bar and saw work very well. I really like the shortness and lightness.
After 3 hours of metered running hours (I've fitted an hour meter to this saw to see how long it goes), I removed and inspected the bar. In use - mostly thinning very small cypress trees in a thicket - it worked perfectly. On inspection I did find some burring of the bar rail edges at the base, on the top side, in the section where the chain meets the bar groove after going around the sprocket. 
see the burred bar edge above the tensioning hole, in the heated section
It looks like the steel I softened here with the gas torch is deforming under chain impact. 
Chainsaw bar rails are heat treated to make them harder, you can see in this photo below: 
This bar lost a patch of paint, showing the heat treatment colours along the rails, bottom side
The blueish strip along the bottom side of the bar shows that there has been some heat treatment - probably induction hardening - to make the groove rails harder and more durable. 
I'm not expecting this to be a problem, as there will be some work hardening of the steel by the chain hitting it, and there is surplus steel in this section. However it is worth keeping an eye on. 

Sunday, 21 May 2017

Baumr SX82 Review – first impressions

Model: Baumr-Ag SX82
My friend Alan asked me to have a look at his new Baumr chainsaw. It’s the 82cc saw, which cost him just over $200, delivered. Before even starting it, Alan made some modifications as suggested by Scott O’Malley on youtube, replacing fuel lines and chain adjusting system which are known problems. 
So far, it has done an hour or so of work, working really well apparently. 
Here are the new fuel lines.

these are some of the replaced fuel lines
Here’s the chain adjuster. The original bevel gear adjuster clearly had soft teeth and appears to have burred over almost on first use.
damaged spiral gear on the chain tensioner
Modified adjusting screw on chain tensioner
He also replaced the decompression valve, after early failure.
replaced decompression valve

Obvious issues

- Plastic cover melted by muffler

- Very weak bumper spike/dog, only on left side of bar. No spike mount provided on the clutch cover, but it could probably be improvised.


The saw would probably crosscut vertically down fine, but it wouldn’t be much fun to use in felling where you depend on the spikes more. Freehand ripping (e.g. cutting logs lengthways into beams) often depends on good spikes, so I wouldn't try it unless I'd installed better spikes. 

Chain and bar

The design of the chain bar is very similar to a 3/8” Stihl bar, with tensioner and oil feed holes in about the same places, but has narrower slot for bar studs.
Baumr bar on studs

Baumr bar on left, Stihl on right

Stihl bar doesn't fit - could with suitable bushes
In nearly new condition, the chain has a lot of clearance in the bar slot, with the chain able to tilt with the tooth corner in line with the bar face.
There should be daylight between straightedge and bar face



This means the chain is right on the edge of having no clearance, and the bar becoming bound in its own kerf. With a little bar slot wear, and the teeth losing set by being sharpened and shortened, the saw would cut very poorly very soon.
Normally if a bar and chain have this problem, I’ll consider hammering the bar slot to make it tighter. However in a new saw this didn’t look like a good idea. Measuring with a vernier caliper, I found the chain drive links measure at 1.4mm and the bar at 1.6mm. 


I tried a Stihl 3/8 chain of 1.6mm gauge (which interestingly measured at a shade over 1.5mm), and it fit well. I would say that the saw was delivered with the wrong gauge chain – I don’t know if they all have this problem. With a 1.6mm gauge chain, bar and chain would fit well.

It looks like they do all have this problem. On the Edisons page where the saw is sold [https://www.edisons.com.au/baumr-ag-24-e-start-pro-series-82cc-petrol-chainsaw-sx82/], the chain is specified as .058” gauge, which is just under 1.5mm - just what I found. However the spare chains they sell [https://www.edisons.com.au/baumr-ag-24-tru-sharp-3-8-pitch-chainsaw-chains/] specifically for this saw are specified as .063”, which is 1.6mm - the right gauge for the bar supplied.
1.6mm gauge chain fits snugly
After cleaning, I noticed chipping on the bar slot rails, just behind the roller nose unit. 
This is where the bar might get some hammering from a slightly loose chain. I’ve seen chipped bar rails plenty of times before, but usually only after bad burring after a lot of wear and neglect to dress the bar. Chipping on a new bar suggests a problem with heat treatment – but perhaps indicates the bar has been heat treated which is at least an attempt at good quality.
The rim sprocket was a perfect match for a standard Stihl 3/8” rim sprocket.
Baumr sprocket

Stihl sprocket

Oil pump [added 30 June 2017]

Our neighbour Shaun also bought an SX82 and gave it a first run recently. After a little cutting, Alan noticed that the chain wasn't getting oil, and there was oil running out from under the clutch cover. Dismantling revealed missing hold-down bolts for the oil pump: easily replaced and the saw back in action soon. During this exercise the clutch drum bearing was found to be totally dry - risking damage to the crankshaft. 

Conclusions

This saw is incredibly cheap. It works and seems quite powerful, but has a range of problems from new which really need to be addressed in order to use it at all. You need to be pretty handy to do all these things. The things that need attention before first use so far include:

  • replacing chain with 1.6mm gauge chain (or bar to 1.5mm) 
  • replacing fuel lines with silicone fuel hose
  • greasing clutch drum roller bearing
  • checking oil pump bolts

We’ll see how this saw lasts over time. Maybe the motor itself is fine, and the saw will become reliable after initial problems are addressed. Perhaps I’ll update this post later...