Nobex saw problem - any ideas?

[Kalimna]

Evenin' folks,
I have just set up a Nobex mitre saw, and I seem to be having a problem cutting dead-on square with it across the face. I am quite happy to accept that it is my technique at fault, but here's the issue - on anything other than 90 degree cut, there seems to be about 3-4 degrees (Im eyeballing, so maybe more, maybe less, but about 1-2mm over 60mm) off from perpendicular across the face of the piece being cut. The actual angle being cut, say 45 degrees, seems spot on, but the 'long cut' is way off. Apologies if my description is a little poor. It's almost as if the upright posts are not at right angles to the base. (there is a slight veering away from square when cutting a 90 degree too.)
Am I expecting too much from this piece of kit (i.e. 45 degree cuts I can go straight to glue up for a box), or am I doing something wrong. And if I am, can anyone suggest a way I might fix the issue?

Thanks, I'm getting rather frustrated with it.
Adam

 

[xy mosian]

I used to have similar problems, I get around it by clamping the wood to the rear fence. Now this isn't easy to do but did get around the problem for me. Having learnt more, here, I wonder if the blade is cutting more heavily on one side. Un-balanced set perhaps. I've not tried yet, but how about clamping some wood in a vice and using the saw as a 'Frame' saw to check the line of cut. If it pulls to one side then a 'stoning' may help.
xy

 

[Kalimna]

xy - I had thought of that to be honest, but am I correct in thinking that if the set is unbalanced, then the cut will be curved slightly rather than just off-angle? Also, it looks like the teeth on the blade are hardened (blueish tint) - will a stoning work on them? I did find that clamping (just a wooden cam clamp) to the rear fence improved things, so perhaps the stock I was practicing with wasnt quite square either?
I shall try your suggestion about using as a straightforward frame saw. Did you find that the tension you placed on the blade made much of a difference?
Thanks for your input,
Adam

 

[xy mosian]

Kalimna,

I had forgotten about the hardened teeth.
I not sure about the curved cut when both the saw movement is constrained and the wood is clamped. I think it's one of those things that can be thought about forever but easily checked by doing. Do let me know what you come up with.
Blade tension? Well I always tried to get it as high as possible, my blades have a nice keyhole shape in them now, it helped a bit. The blade holding is poor I think. I can well see that there may be some slight rotation of the blade with respect to the frame.
Has that just given me another train of thought? What to do to fix the blade alignment in the plane of the frame? After all there may be, will be, some play of the bolts where they pass through the frame and the blade hole is only in point contact with the pin an the end of the blade clamp. I can see a blade clamp modification on the horizon.

Don't know if I've helped at all.
xy

 

[Lons]

I'm still using my original from more than 20 years ago. We sold loads of them in the 80s even though expensive as there was nothing else on the market like it.

IMO you can't easily achieve exact results straight from the saw and need a disk sander or shooting board to finish. It is possible with care to get reasonably accurate however by cutting slowly and letting the blade cut rather than exerting and downward pressure, needless to say, the blade must be sharp! The blade being flexible is easily deflected.

Have Nobex discontinued the clamp which was supplied with the original, along with and extender rest attachment?.

My Nobex btw is like the old broom joke as it's had 2 "new" handles fashioned out of old hardpoint handsaw handles :lol:

Bob

 

[chippy1970]

Ive still got my 20 + year old black nobex I bought as an apprentice. Maybe you should tighten the blade tension a bit, if there is any slack in the blade that could cause problems.

 

[Kalimna]

Thanks for the input folks.
I had a prolonged session in the garage yesterday, and came to the conclusion that cutting as slowly as possible helps, that the blade tension is probably good enough (as tight as I could get it with hand tightening), but as suggested above, to get exact results straight from the saw is probably expecting too much.
The end result of which is I now have a newly fabricated shooting board (made up from 1" marine ply) with 45 degree mitre fence and donkey ear (that was fun to make!), and slightly adjustable main fence (thank you Cornish Workshop ). And the best bit is, it seems to work! I just need to get an accurate (not sure that cheapy plastic geometry set from Tescos is good enough to read easily) 45 degree reference to check it out on...

XY - I realise that often the best way to know what will happen in a particular situation is to just go ahead and try it, but I frequently think too much (getting the wrong end of the stick being a common occurence!) and like to work out in my head what will happen. With the saw cut, if the set is unbalanced, then on each cutting stroke a little bit more would be taken off one particular side leading to a curved cut (however slight). If the cut itself is straight (even if off-angle) then the set is in balance...

Cheers,
Adam