How good is good enough .... or.... am I wasting my time?

[Zeddedhed]

I've got a Bosch glide arm chop sliding mitre saw (GCM 12 GDL) which is about 1 year old, maybe a bit more.

It's bolted down to a stand and never leaves the workshop. It makes the vast majority (99.9%) of it's cuts at 90 degrees with the odd mitre here and there.
It's well looked after, hoovered out every night and has a dedicated extractor. It's never been dropped.

Now that I've set the scene, here's the thing....

When crosscutting a lump of Oak 80 x 50 that's been trued up I'm getting a non-square cut. The lack of squareness is top to bottom of the cut (the Bevel). The cut starts off on the line or mark (obviously) but then undercuts by a shad.

I know the photo shows the cut hollow rather than undercut but thats just the 'photo.

Is this me being ultra fussy or is this the best I can expect from what is essentially a builders tool?

EDIT: By the way, I've adjusted the tilt/bevel to spot on 90 degrees using a digital angle finder, so I guess I reckon the blade is deviating mid cut.

 

[dzj]

It might help to have the blade sharpened.

 

[Benchwayze]

Zed...

I don't know much, but I once used a 'wobble-saw' regularly, for finger joints etc.. The bottoms of the cuts were always slightly scooped, for obvious reasons. So could you have some wobble? I can only envisage the blade wobbling if it isn't at 90 degrees to the axis of the arbor, or if the arbor was out of true. But that would result in hollowing across the thickness rather than the width. (I think!)

I might also suspect some slop in the slide mechanism, although I thought the new Bosch isn't supposed to suffer from that. So, is there any misalignment in the co-axial joint? (Or whatever it's called? ) Maybe there is some adjustment that needs to be made.

Initially though, if it has cut well over the last year, then as suggested, you could get the blade sharpened, and see if it helps. Personally, if all else appeared in order, I would suspect the blade is distorted, and take the chance of investing in a top quality blade. (If you don't already have a good one!)

HTH.

John

 

[Ed Bray]

Can you undertake a four cut test, this magnifies the error and allows you to work out the required correction.