Fixed mitre saw questions - deflection & temperature impact

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sammy.se

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HI All,

I have a DeWalt DW703 non-sliding mitre saw. It's a solid, powerful machine which I use for framing/structural work, but also finer woodwork.

A couple of issues I thought I'd pic your brain on:

1) Adjustment. I'll always check everything is very square before I start work. This is done using an engineer's square, and test cuts, and an angle finder. The issue I have is, when I carefully put it away totally square (under the bench), the next time I use it, it needs adjusting again! Is that normal? The only thing I can think of that that when I start work, the saw and workspace is cold, and so the various bits of metal in the saw has moved ever so slightly... which sends me down the circular task of adjusting and readjusting. Could temperature be a factor here? Should I warm up the workspace and tool before I start work?

2) For the framing/heavy duty stuff, I use the DeWalt 24T blade - great for rough work, slices through anything like butter. For the slightly finer work, I have a 48T Lidl blade (yes yes, don't laugh) - which has a decent cut quality - my expectations are adjusted for the fact that it is a Lidl blade. HOWEVER - there is noticeable deflection across the cut, where it is square near the fence, but further away from the fence, the cut bends ever so slightly. Also, in birch plywood, the deflection is vertical, downwards through the cut (in softer MDF this doesn't happen). Can you even have deflection in non-sliding mitre saws (I thought you couldn't)? Would a better blade - like this Freud 80T pro - prevent this deflection?

Thanks!
 
Cheap mitre saw blades don't have any (or very little) anti vibration slots in them.
As they cut, the blade starts to resonate or vibrate which in turn creates a wider & therefore inaccurate cut....you can see and feel it sometimes as the cut proceeds.

It may be okay when cutting up some rough 4" x 2" for a stud wall for example, but it will be very noticeable on a piece of joinery or sheet material.

My own preference for blades for my table saws & mitre saws are the Dewalt Series 60 blades. They have distinct laser cut anti vibration slots in them....Out of the saw, when you flick the blade plate with your finger, they dont "ring", they just sound dull. Absolute minimum vibration in use.

An example shown below.

https://www.ffx.co.uk/tools/product...21-250Mm-X-30Mm-X-60T-Extreme-Mitre-Saw-Blade
 
Thanks, that makes sense. You are correct, no anti-vibration slots on my cheapo blade.

I will be cutting pieces of oak veneered sheet goods at some point - MDF and Ply - do you think there is much difference between the 80T and 60T for that purpose?
 
For those type of materials, I don't think there would be much of an advantage gained by using an 80 tooth blade rather than the 60 tooth.

I do use an 80 tooth blade on pre-painted MDF material as it does give a slightly superior cut on the painted surface.
 
Blunt blades possibly, I work on the rule if I rub my thumb over it and it's not catching the skin it's blunt.
I'll change 3-4 blades a week, dull blades cause all sorts of weird cuts.
 
Blade choice as above is key. However, I am wondering why you need to check your saw every time. Does it frequently need adjusting?

My 12" mitre saw (GCM 12 - Bosch), fixed to it's portable stand, has been tipped right over twice and even that didn't put it out of square. If your saw is constantly requiring adjustment then I would go round every bolt and tighten it all up.

Blade vibration is not helping I guess.
 
Last edited:
Blade choice as above is key. However, I am wondering why you need to check your saw every time. Does it frequently need adjusting?

My 12" mitre saw (GCM 12 - Bosch), fixed to it's portable stand, has been tipped right over twice and even that put it out of square. If your saw is constantly requiring adjustment then I would go round every bolt and tighten it all up.

Blade vibration is not helping I guess.

Thanks, I'll check all the bolts again.

Yes it frequently needs adjusting, or I should say I *think* it does - but maybe I'm in a vicious cycle due to the poor blade making bad cuts, and I'm trying to solve that through adjustment.
Sounds like I need to put a sensible blade in there and then figure out if there is truly a problem with adjustment.
 
I swapped out the cheapy blade with a smaller, Axminster blade from my table saw.

On the first cut I could feel how smooth it was - no more vibration, and it's much sharper.

Cuts are perfectly straight now. I've tightened everything up so hopefully the adjustment is sorted too (will check in a couple of days)

Thanks for the quick advice above - all spot on.

PS, serves me right for trying to get by on an ultra cheap saw blade
 
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