Got my new axminster catalogue but have a question

[devonwoody]

New catalogue arrived this morning, they are stocking Festool.

However looked at the CMT rip blades for tablesaw and they have kerf spec at 1.7 & 2.4mm

My riving knive is for a 3.2 blade.

Does this mean to use a cmt blade I really need to take off the riving knive (which is a bit of a pain anyway)?

 

[devonwoody]

The cmt 271 blade states that it is an anti kickback design , so does that mean that the riving knife is not needed for the kickback protection?
I appreciate guard and splitter needs consideration.

 

[Fecn]

Yep.. if you want to use a thin-kerf CMT blade then your current riving knife will be too big. I would recommend fitting a thinner one rather than removing it altogether.

 

[devonwoody]

Appreciate your advice.
I have been watching some American videos and they are not using a riving knive, (counted their fingers, one old boy 79 years of age Tage Frid and he has still got a complete set) seem to be getting away without them.

I'm thinking a splitter fitted to an insert plate for lightwork joinery could suffice and putting the riving knife back for heavy ripping might be the way I could go.

 

[jasonB]

I use the 290series for ripping, has a 2.8mm kerf but no Anti-kick back. The 271 is really only a for handheld saws not tablesaws due to the diameter only being available in 184 (7 1/2")

You should still use a splitter/riving knife with the Anti kickback blades as the timber can still close on the side of the blade.

Jason

 

[devonwoody]

JasonB, In the next column of the Axminster catalogue they do a 250 & 300mm version using the same pattern number 271.

So does the anti kick back spec. mean that the riving knife should not be needed for that purpose. I acknowledge the other attributes.

 

[jasonB]

If the wood closes onto the back of the blade it will be lifted off the table, in this situation the AKB has little effect. The AKB is more to stop you feeding in too fast and having the blade take too big a bite and spitting the wood back out at you.

I would still make a riving knife, scrap of steel or even alloy would do, just trace round the existing knife.

Jason

 

[devonwoody]

Point taken Jason.

Going a new riving knife route is acceptable to me but wanting to avoid the knife being above the blade. So what about a splitter the correct thickness?

 

[ProShop]

JasonB, In the next column of the Axminster catalogue they do a 250 & 300mm version using the same pattern number 271.

So does the anti kick back spec. mean that the riving knife should not be needed for that purpose. I acknowledge the other attributes.

Antikickback and the riving knife are two different issues. You should really still use a riving knife for the reasons Jason mentions in his above post.

Antikickback is mainly to prevent feeding the timber into the blade to fast purely by limiting the size of bite of the teeth into the timber (the same principle on a spindle moulder when hand feeding), especially on varying grain direction on a particular piece of timber for example.

hope this helps

Arghhhh can't type fast enough, Slow down Jason
..

 

[chippy1970]

New catalogue arrived this morning, they are stocking Festool.

However looked at the CMT rip blades for tablesaw and they have kerf spec at 1.7 & 2.4mm

My riving knive is for a 3.2 blade.

Does this mean to use a cmt blade I really need to take off the riving knive (which is a bit of a pain anyway)?

They have always stocked Festool

 

[jasonB]

Can't see a problem with a splitter thats just below the height of the blade, assume you will make your own arrangements for protecting the top of the blade :wink: Though the crown guard being fixed through the riving knife stops and chance of the wood being lifted by more than a few mm.

Not too happy fixing the splitter to the insert though, if the timber did tighten onto the splitter and then get lifted by the blade it would take the insert with it.

Jason

 

[devonwoody]

It was the mitre drop saw that made me think Festool was new to Axminsterm mind you I dont like the price.

So where am I likely to get material suitable for a 1.7mm splitter/riving knive?
I have no engineering equipment to cope with making one of these.

 

[stuartpaul]

I seem to remember in the good old days of the woodworking machine regs (unfortunately I go back that far!) the riving knife was supposed to be saw plate thickness plus 10%.

I would never use a table saw without a riving knife but that is just a personal thing.

Stuart

 

[jasonB]

A hacksaw and a file should do you, maybe a twist drill as well. Or if you have a bench mounted belt sander that could be used as a linisher

An old kickplate or finger plate from a door would do, or failing that one of the model engineering suppliers will do 6" squares of suitable steel or brass 16swg may be a bit tight at 1.62mm so 18swg at 1.22mm may be a better option.

Try these suppliers

http://www.collegeengineering.co.uk/
http://www.btinternet.com/~ekp.supplies/
http://www.chronos.ltd.uk/

J

 

[devonwoody]

Thanks Jason, when I locate some plate material, I will obtain blade mentioned above.

 

[Digit]

That's correct Stuart, but you are confusing blade width with kerf width.
It would be a very unusual saw blade that did not cut wider than its own width.
My SIP cuts about 0.2mm wider than blade width on hardwoods.

Roy.

 

[jasonB]

The riving knife should be thinner than the kerf but thicker than the blade body, this can be quite a tight tollerance as the carbide tips of ultra-thin kerf blades do not overhang the body by much. Bit more info here

Jason

 

[Richard Findley]

Hi,

Just a thought.... If your current riving knife suits a 3.2mm blade and you get a 1.7mm blade you'll only have something like .75mm extra each side of the blade to deal with. I think I'd be tempted to try it out with your existing knife because I really can't see what difference 3/4 of a mm is going to make!!

Once you've tried it out, I'd be interested to hear of any negative results, if indeed there are any??

Good luck,

Richard

 

[tim]

Hi,

Just a thought.... If your current riving knife suits a 3.2mm blade and you get a 1.7mm blade you'll only have something like .75mm extra each side of the blade to deal with. I think I'd be tempted to try it out with your existing knife because I really can't see what difference 3/4 of a mm is going to make!!

Once you've tried it out, I'd be interested to hear of any negative results, if indeed there are any??

Good luck,

Richard

It won't work! The riving knife is twice as wide as the cut you are trying to slide passed it. It might work if the timber is very thin and flexes past the knife but anything more rigid will jam or stop. Dangerous and foolish to do.

 

[Slim]

Hi,

Just a thought.... If your current riving knife suits a 3.2mm blade and you get a 1.7mm blade you'll only have something like .75mm extra each side of the blade to deal with. I think I'd be tempted to try it out with your existing knife because I really can't see what difference 3/4 of a mm is going to make!!

Once you've tried it out, I'd be interested to hear of any negative results, if indeed there are any??

Good luck,

Richard

The timber will jam on the riving knife. No doubt about it. A thin kerf blade requires a thin knife, and the riving knife must never be thicker than the kerf of the blade.