Thread: Table saw blade

So do I, it was my idea to get the blade in the first place because I'd read all the technical stuff and it made sense. I guess sometimes the theory doesn't always translate to reality.

EJ

Is the saw to which you are referring a true radial arm saw or is it a framing saw. The reason I ask this is that a RAS head can be swivelled 90 degs to the fence and used to rip. The framing saw can only crosscut (including bevelling and angle cutting) with it's fixed head. I have had a couple of framing saws but never owned a radial arm saw.

My understanding is that you have to be extremely careful when using the RAS in ripping mode as significant positive rake can lift the board and send it right back at you and it is for this reason the negative rake blade is recommended. I would imagine that it is a poor performer even when used correctly.

Regards
Paul

It's a real RAS, OMGA RN700, swivelling arm, tilting and rotating head. Only ever used for rough docking and non-critical cuts because every time it binds mid-cut it throws my alignment out and I can't be bothered fixing it every 6 weeks.

I can't imagine why anyone would use the rip function, I certainly wouldn't want to be near it with no riving knife.

EJ

I think you have the answer in your useage. No ripping means no need for the positive rake.

Regards
Paul

The only blades we use are positive rake. Negative was uncontrollable.

EJ

Sorry, I got that around the wrong way. I should indeed have said no need for negative rake. In fact I think that is normally a feature of blades designed for cutting aluminium.

Regards
Paul

Yes, negative rake triple chip is for non-ferrous metals, but zero or neg. rake ATB is specifically sold as a RAS crosscut blade.

https://www.cuttingedgesaws.com.au/s...-saw-carbitool
Carbide Tipped Saw Blades for Radial Arm Saws | The Blade Mfg. Co
Freud Tools | 10" Thin Kerf Sliding Compound Miter Saw Blade

Originally Posted by rrich

I understand completely what you are saying. I do not disbelieve your experience. The engineer in me wants to understand why you had the experience that you did with the negative hook angle blade.

Originally Posted by elanjacobs

So do I, it was my idea to get the blade in the first place because I'd read all the technical stuff and it made sense. I guess sometimes the theory doesn't always translate to reality.

like Rich, the engineer in me wants to understand how you had your experience.

were you pulling or pushing the blade through the work?

Originally Posted by Bushmiller

. . In fact I think that is normally a feature of blades designed for cutting aluminium.

Because these days I mainly use my TS to cut Al and plastic, a 100T triple chip negative raked blade has been the standard blade on my TS for the last few years.
I only swap it out when ripping or am going to cross cut larger pieces.

Being high TPI and negatively raked this blade cross cuts timber slowly but with a very fine finish similar to my 100T positively raked blade and as expected I find I have to push a bit harder than the 100 toothed positively raked blade. The blade is a Chinese made Bosch Branded and it cost about $70.

At the mens shed we have an older, HD, RAS that came fitted with a positively raked blade. The shed ning-nongs have all been shown how to use it correctly but they occasionally they still pull it too fast so that it climbs up onto the work and stalls the motor. I recommended all work be clamped against the back stop and we try a negative or zero raked blade but the sorts of things they sometimes cut with it are often oddly shaped so they cannot be easily clamped. So rather than have the saw spit the work pieces at the operator we have stayed with the positively raked blade. I get the herbie jeebies watching some blokes use that saw - another reason why I go there as little as possible.

Originally Posted by elanjacobs

Yes, negative rake triple chip is for non-ferrous metals, but zero or neg. rake ATB is specifically sold as a RAS crosscut blade.

https://www.cuttingedgesaws.com.au/s...-saw-carbitool
Carbide Tipped Saw Blades for Radial Arm Saws | The Blade Mfg. Co
Freud Tools | 10" Thin Kerf Sliding Compound Miter Saw Blade

Elan, I have only seen negative rake recommended for MITRE saws never RAS saws.

Originally Posted by Chris Parks

Elan, I have only seen negative rake recommended for MITRE saws never RAS saws.

Well, all 3 of those links say RAS and I've seen it from other manufacturers as well

Hi Elan

I agree with your shrug.

This is what Rollie Johnson -- FWW's tool guru -- has to say about Radial Arm saws:
Radial arm saws have a reputation as being dangerous, overly-aggressive-cutting saws, but the real culprit isn’t the saw, it’s the blade. Radial arm saws require a negative hook angle blade, just like a chop saw. Standard positive hook angle blades simply cut too aggressively for a pull saw,
http://www.finewoodworking.com/2016/10/20/9-dewalt-radial-arm-saw

Originally Posted by ian

Radial arm saws have a reputation as being dangerous, overly-aggressive-cutting saws, but the real culprit isn’t the saw, it’s the blade. Radial arm saws require a negative hook angle blade, just like a chop saw. Standard positive hook angle blades simply cut too aggressively for a pull saw,
http://www.finewoodworking.com/2016/10/20/9-dewalt-radial-arm-saw

That's the exact thing I'm calling BS on

In a survey of 283 WW injuries undertaken in 1996, there were 4 related related to RA injuries.
While these are small number stats RAS showed up as by far the machine with lowest level of "Exposure to first injury" - whatever that means
On reading teh research paper think it means hours working in a workshop that had an RAS available for use.
RAS users that suffered an RAS injury had on average ~1500 (38 weeks) hours of exposure before their first injury, the next lowest are jointer/planers with 3700 hours of exposure to first injury

However in terms of incidents per 1000 person hours of actual use, RAS had 2.7 incidents which is similar to bandsaws (2.6), jointer planers had the highest at 4.9.