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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...

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