Riving knife with crosscut sled

[matt carpenter]

Hello, could some help with some advice please?
I am constructing a cross cut sled for my Dewalt 745 site table saw and have got to the stage of cutting the back fence but am concerned how to do it without removing the riving knife first!! which is something i have never wanted to consider doing, as you can see in the photo i can not cut through it as the knife is higher than the blade so i assume that is the only way to go about it, could someone let me know if i am missing an alternative method or if this is the only way ahead and could you advise on how to make it as safe as possible please?
Thank you in advance for any help with this.

 

[pgrbff]

How do you partially rip through a board to make a rebate with such a high riving knife
?

 

[matt carpenter]

How do you partially rip through a board to make a rebate with such a high riving knife
?

I use the router table for that, havent tried blind cuts on table saw yet still getting comfortable with it.
Is this riving knife higher than standard? maybe i could look into getting a smaller one.

 

[pgrbff]

Mine is adjustable and my understanding was that it should be a touch lower than the blade height. Others will know better than me.

 

[matt carpenter]

Mine is adjustable and my understanding was that it should be a touch lower than the blade height. Others will know better than me.

Thanks, i have been doing some more research and it looks like my model is quite old type1 and they only supplied it with the riving knife and guard combination the newer model has a lower knife but does not fit my machine!! seems the only option is to cut it down or cobble one together out of another one, neither option really appeals or is in my comfort zone to try

 

[Jacob]

Hello, could some help with some advice please?
I am constructing a cross cut sled for my Dewalt 745 site table saw and have got to the stage of cutting the back fence but am concerned how to do it without removing the riving knife first!! which is something i have never wanted to consider doing, as you can see in the photo i can not cut through it as the knife is higher than the blade so i assume that is the only way to go about it, could someone let me know if i am missing an alternative method or if this is the only way ahead and could you advise on how to make it as safe as possible please?
Thank you in advance for any help with this.

Take off the riving knife, cut with workpiece firmly held against a fence, use two push sticks - one pushes forwards (from somewhere between the fence and the blade), the other pushes in towards the fence, do it in one steady move and don't stop until right through.
Have a practice with some small offcuts?

 

[Agent_zed]

A couple of thoughts, which hopefully others will confirm as sensible....

1. You could make another riving knife. It doesn't have to be anything fancy it is just there to stop the wood closing on the back of the blade.

2. If we think about what the riving knife is doing (see point 1) it is there to stop big pieces of wood closing in on the blade. With a sledge like yours the max length of the wood is very short so the chance of the wood closing is very low. The dangerous part with no riving knife is that it clamps and rides up and is then thrown at the operator. With a sledge this in not going to happen as the rear of the wood is against the sledge. You could (and I would) add a guard over the top on the sledge which would definitely stop a piece of wood flying at you. Although you have clamp rails so if you use clamps that shouldn't happen anyway.

A couple of thoughts I had when thinking about building a sledge...

Blade cover as mentioned above
something spiky so you can't accidentally put your hand where the blade goes and/or a small box with a perspex top at the rear that as the blade goes through it stays in this boxed area and doesn't just get exposed.

whether that is a good idea I've yet to find out.

Also I made a very simple emergency foot switch on an extension lead. If things start going wrong its an option rather than taking your hands off the sledge and trying to reach for the off switch, which on mine is slightly under the top and not as easy as I'd like it to be.

 

[pgrbff]

I think Sautershop sells a large variety of riving knives. I confess I remove the riving knife when using the crosscut sled as the piece I am cutting is rarely deeper than the part of the blade protruding.

 

[matt carpenter]

A couple of thoughts, which hopefully others will confirm as sensible....

1. You could make another riving knife. It doesn't have to be anything fancy it is just there to stop the wood closing on the back of the blade.

2. If we think about what the riving knife is doing (see point 1) it is there to stop big pieces of wood closing in on the blade. With a sledge like yours the max length of the wood is very short so the chance of the wood closing is very low. The dangerous part with no riving knife is that it clamps and rides up and is then thrown at the operator. With a sledge this in not going to happen as the rear of the wood is against the sledge. You could (and I would) add a guard over the top on the sledge which would definitely stop a piece of wood flying at you. Although you have clamp rails so if you use clamps that shouldn't happen anyway.

A couple of thoughts I had when thinking about building a sledge...

Blade cover as mentioned above
something spiky so you can't accidentally put your hand where the blade goes and/or a small box with a perspex top at the rear that as the blade goes through it stays in this boxed area and doesn't just get exposed.

whether that is a good idea I've yet to find out.

Also I made a very simple emergency foot switch on an extension lead. If things start going wrong its an option rather than taking your hands off the sledge and trying to reach for the off switch, which on mine is slightly under the top and not as easy as I'd like it to be.

Thank you for the points for thought.
I dont think i would be comfortable making my own knife as have done a little research and you can get it wrong quite easy, i like your safety ideas and will look into incorporating something like that, and i can also see the logic in not needing the knife in while useing the sled, so am considering trying that, thanks againg for your help.

 

[matt carpenter]

I think Sautershop sells a large variety of riving knives. I confess I remove the riving knife when using the crosscut sled as the piece I am cutting is rarely deeper than the part of the blade protruding.

Thanks for the link i will have a look there, also i can see the logic in taking the knife off so might try that myself.
Thanks for your help

 

[Ttrees]

This bit in Kelly Mehler's video might be of interest

 

[matt carpenter]

This bit in Kelly Mehler's video might be of interest
View attachment 163323
View attachment 163324

Thanks Mark looks interesting

 

[Ttrees]

Not my video, just included the utube so you can find it.

 

[Orraloon]

I have to take the riving knife off to use a sled on mine too. Not a problem as I see it as you are crosscutting or doing non through cuts. A top guard can be built on to a sled too.
Regards
John

 

[Doug71]

Never a good idea to remove the blade guard or riving knife from a table saw, it's an accident waiting to happen.

 

[hlvd]

Never a good idea to remove the blade guard or riving knife from a table saw, it's an accident waiting to happen.

Absolutely, YouTube has a lot to answer for!

 

[sometimewoodworker]

A riving knife is slightly less necessary when using a sled, however I would use one unless there is a very good reason not to use it. That is precisely why I got a low level knife made for my saw. So I now have both a riving knife that holders the blade guard and a knife that holds an overhead blade guard.

 

[llywmog]

I bought an additional standard riving knife for my Makita and followed this hack to cut it down to size. Works perfectly.

 

[MikeJhn]

IMO it's using the wrong machine to cut a grove, should be done on a Router table, easier and safer, as said above removing the riving knife and guard is an accident waiting to happen, even a track saw would be safer.

 

[matt carpenter]

IMO it's using the wrong machine to cut a grove, should be done on a Router table, easier and safer, as said above removing the riving knife and guard is an accident waiting to happen, even a track saw would be safer.

Thanks Mike i agree i also cut dados with the router table, i am trying to find a way of using the table saw with a crosscut sled and the riving knife is too high, not comfortable with removing it myself so am on the hunt for a smaller one.