Thread: Let the magic smoke out of my 235mm circular saw

Good Morning Ed

With horsepower, everyone knows that there are draught horses and shetland ponies. I suspect that something similar applies with electricity - there are big watts and little watts.

My 25+ year old 235 mm Hitachi died last year after a most productive life. Great tool, and very robust.

Note you said that you were cutting 75 mm slabs. I would always cut this with three passes of 25 mm - otherwise you can get burn marks that indicate that the saw is labouring, and you have more clean-up later.



Fair Winds

Graeme

There doesn't appear to be burn marks on the saw blade or the timber as they are quite clean, not overly worried about any extra clean up at this stage as these rips are only to reduce the weight of these pieces of timber so that I can man handle them easier than the up to 80Kg weight that they are now. After they get ripped they will go onto my table saw for further ripping, then storage so that they can dry out and finally through a jointer to dress them down to size and take out any warpage. So there is still a lot of work to be done to the timber before it is ready to use. I put the Hitachi though another 4 hours ripping and it handled it like a champ without straining, unlike my back which is feeling it!

Cheers.

Ed.

I would still be very careful about doing lots of 75 mm ripping with any hand held circular as they are not designed for this.
Yes with something like a Hitachi or Makita you can get away with it for longer than a cheapie for precisely the reasons you stated, but ultimately it might suffer the same problem.
To reduce the risk I would still follow GCs advice make sure the blades are kept sharp and stop as soon as the saw starts to feel warm.

For breaking up big slabs I use a chainsaw and home made mini monorail mill like this

As usual my stuff is WAY over engineered and there are much cheaper and simpler models like the beam machine
These can also be used to completely saw up small logs.

Mills like these can be combined with a reliable electric chainsaw of similar power as your circular but they will not be stressed as much as the circular.

Something I do when I'm (ab)using a cheap piece of machinery....(a Ryobi power drill I've had for years for example, last job was drilling 12mm holes in 3mm steel)....is, after hard use, stalling the motor, signs of heat, smoke etc, I run the motor on no load for 30 seconds or so. Most motors are fitted with a cooling fan of some sort.......seems to work. May just be elecktrickery superstition.

Sound advice all round.
The only thing that I would add is to maintain operating revs as high as possible to maintain armature cooling.

Originally Posted by Ed..

Today I had some 75mm slabs to rip to make them more manouvarable so that I could put them on my table saw more easily for futher ripping, so I went out and bought a 909 Timbercat 235mm Circular power saw as they were on special from about $150 down to $97. I did ask the woman on the phone before I went out to buy it if they were suitable for what I intended to do with it and she said yes, that they weren't industrial quality but would do the job, even though I had my reservations and that alarm bell from my inner voice was clanging away in my head, but it was a 2000W saw so technically it should have had enough grunt.

Anyway I put on a 20 tooth thin kerf ripping blade and proceeded to rip, each slab was about 2.3m long, by the end of the 5th cut the smoke had started to escape and then it stopped. I had about 10 minutes between cuts. So I returned it and got my money back and then proceeded to Trade Tools and got a Hitachi 235mm saw at a good price which I should have done from the get go. Only got 1 rip done because it started to rain by then but the Hitachi seemed to go through it much easier than the Timbercat. So I guess 2000W is not the same for every make! Apparently the wattage stated is the imput wattage but different motors put out different output wattages (actual work) for a given imput wattage so some motors are way more efficient than others and are probably better built with heavier wire!

So lesson leant, go with the inner voice! I paid just a bit more than double for the Hitachi but I think that it will work for a long time yet.

Cheers

Ed.

Hi Ed

a 20 tooth blade seems to have too many teeth for the task.
the rule of thumb is 3 teeth in the cut. Teeth Number | Circular Saw Blade
for a 235 saw cutting at max depth of cut -- I'm estimating around 16 teeth

Originally Posted by ian

Hi Ed

a 20 tooth blade seems to have too many teeth for the task.
the rule of thumb is 3 teeth in the cut. Teeth Number | Circular Saw Blade
for a 235 saw cutting at max depth of cut -- I'm estimating around 16 teeth

Hi Ian, I actually looked for a 16 tooth but no one had it in 235mm, went to Bunnings, Masters and Trade Tools so 20 tooth was as good as I was going to get, the Hitachi doesn't have any issues with it though and works well. I didn't have time to wait for them to order one in so will make do with the 20 tooth, I only have another 12 or so cuts to make, then the fun begins on the table saw.

Cheers

Ed.