Circular Saw stopping

[Adam W.]

Tried an 18V 5amp/hr saw to rip 50mm oak....Total rubbish. It managed 6 inches before it died.
Used a 36V 5amp/hr saw to rip 50mm oak....Not so rubbish.

Same amp/hr, same Makita batteries, new blades on both.

As I said upstream 18v saws are for ply, OSB and battens.

 

[Spectric]

That reminded me of when I brought some 4x2's and wanted them cut into three to get them into the car, the guy had a cordless Dewalt which did three cuts before going no further so he went and got there old corded Dewalt which just cut them like butter with no complaints. There is a lot to be said for corded tools which have infinite A/h capacity and continous power. The same can be said for my old 110 volt Bosch circular saw, that cuts softwood without any issues but is not happy with hardwood.

 

[Sideways]

It's Volts that counts with a saw, not amps. Amp hours is just a measure of how long the battery will deliver the volts.

If you want to cut 40mm stuff a 36v saw is what you want. 18v saws are for ply, OSB and roof battens.

You're a bit out of date on that Adam
Single 18v battery / 1800W corded equivalent and a 70mm depth of cut
https://www.bosch-professional.com/gb/en/products/gks-18v-70-l-06016B9001
More seriously, I like small light batteries in my own tools. 2ah and 4Ah single row batteries are light and have great handling but to get full power out of my own cheap circ saw or the good angle grinder I have an 8Ah and a high drain 5.5Ah battery that are able to provide the current needed for their motors to deliver full power.

 

[Adam W.]

You're a bit out of date on that Adam
Single 18v battery / 1800W corded equivalent and a 70mm depth of cut
https://www.bosch-professional.com/gb/en/products/gks-18v-70-l-06016B9001
More seriously, I like small light batteries in my own tools. 2ah and 4Ah single row batteries are light and have great handling but to get full power out of my own cheap circ saw or the good angle grinder I have an 8Ah and a high drain 5.5Ah battery that are able to provide the current needed for their motors to deliver full power.

I'm 6 months behind the curve....That makes me positively fossilised.

Tell us how you get on with that 70mm depth of cut in a real world scenario.

 

[Sideways]

Hmm - even my bottom of the range little brushed thing will do it's 57mm spec in green oak with an old blade + proper battery ...

 

[TomGW]

I have a Milwaukee 18v cordless saw, plus 4 and 5ah batteries but would never think of using it where mains power is available. I have a 25-30 year old Skil that, with a decent, sharp blade will just fly through everything.

 

[Adam W.]

Hmm - even my bottom of the range little brushed thing will do it's 57mm spec in green oak with an old blade + proper battery ...
View attachment 170616

That's not a very long cut thobut.

 

[Sideways]

Nope. But I don't have a rip blade for that so best I could show was a crosscut in what was lying around...

 

[Stevekane]

I's probably a combination of blunt blade and too small batteries.

I have some 1.5ah & 2ah18v Makita batteries for my drills and they are designed to not fit some of their higher draw tools (unless you adapt them ) as they don't have enough oomph.

Does that saw have a riving knife, if not the cut could be closing up and be binding on the back of the blade.

If you are cutting along the grain in solid wood you want a blade with a low tooth count.

I was going to say the same thing, I dont have the Makita saw and kit at home to look at but I do know that the one small capacity battery I have will not fit the saw, I guess because Makita know that its not powerfull enough, I think you will be going down the wrong path buying blades, the saw is as you describe running out of charge. Cant you borrow a saw off a mate for this job?

 

[TheUnicorn]

I'd say whether or not the battery is a factor (it is), unless the funds just aren't there, you'd still be advised to buy a good quality blade for the job, it can only improve the finish and won't be wasted money unless you'll never use that blade again.

 

[BarbaraT]

Hmm - even my bottom of the range little brushed thing will do it's 57mm spec in green oak with an old blade + proper battery ...
View attachment 170616

If it's the same as the GKS 55, they get the extra capacity with an extra set of gears..
Most circular saws cut one gear into the motor shaft and then have a larger gear that the blade mounts to..

There is a reason the saw it the photo has an 8.0ah battery attached.. I would agree with what everyone says, your 1.3 and 2.0ah batteries can't provide the current required.. the voltage plummets and the saw is gutless.

As everyone says Blades do also make a big difference.... More teeth cause more drag. along with a dirty blunt blade..
Lots of teeth also don't always improve cut quality.. especially if you are cutting something thick.. 80T+ are great on thin wood.

There is also a balance with kerf thickness, super thin blades will cut faster and draw less current from the battery.. The downside is if a cheap thin blade does get too hot and goes out of shape, it then drags more and gets even hotter, and ends up bannana-shaped.

 

[CowboyBeBop]

UPDATE:

I bought a new battery (4.0Ah) and a fresh blade (Saxton 60t TCT Thin Kerf), and here are my non-scientific conclusions, using the same 40mm beech worktop:

• 2.0Ah Battery and original Dewalt blade: You can feel the saw overworking straight away, and it tends to burn.
• 4.0Ah Battery and original Dewalt blade: Similar to the above, but with a bit more power. I didn't push it to the limit.
• 2.0Ah Battery and new blade: It cut fine. Probably could have completed the entire cut with just one battery.
• 4.0Ah Battery and new blade: No problems. The cut was very clean.

Conclusion: While the new battery helps, I believe, in my case, the old blade was the major issue. I underestimated how cutting laminate flooring boards blunted the blade, and I also think that more teeth helped in this type of application.

Thank you, everyone.