Riving Knife

**Big Shed** · 21st October 2007, 04:31 PM

My tablesaw has the riving knide incorporated with the blade guard. This is a very good arrangement, it raises and lowers with the blade.

However, there is one draw back. If you need to remove the guard, eg for a captured cut, you are left without a riving knife/splitter.

As I am also in the design stages of making an overhead guard, I decided to make a separate riving knife. The current riving knife -s 2.5mm/0.1" thick and I was able to obtain some aluminium of the same thickness from Capral Aluminium whilst I was in Adelaide recently. I also bought some sail track from them while I was there, $10.45 fro 4m sounded like a good deal to me.

First shot show existing arrangement with home made zero clearance insert.

Second shot show riving knife, height is just below a 10" blade.

Third shot shows riving knife in place, last 2 shots show how the riving knife moves up and down with the blade.

The 2.5mm aluminium was very easy to cut on my bandsaw, finished off on belt sander and hand filing.

Enough aluminium for 4 riving knifes cost me a whole $5.00

Now on to the overhead guard with dust collection incorporated.

**martrix** · 21st October 2007, 05:10 PM

Nice job. But I foresee anger in your shed.

Any slight bumps on that and its going to go out of shape (not straight). Each bump, re-straighten, bump etc will also soften/fatigue the ally even further.

Anyway, I might be wrong and I guess it could be a good template for a steel one in the future. I made mine out of steel and it was a pain in the ass. It would have been easier if I started with the right thickness of steel, but being a tightwad I used a scrap thicker than needed and ground/lapped it down to size.

**Big Shed** · 21st October 2007, 05:19 PM

Thanks Martrix, I did give that some consideration and you're probably right.

I have been looking for some mild steel or stainless at that thickness, but no luck so far.

I'm a hopeless metal worker, so I'll stick with the ally for now till it gives me grief.

Does your overhead guard have dust extraction?

Perhaps you could put up some pics and sizes, particularly of how you mounted it?

**martrix** · 21st October 2007, 05:36 PM

Originally Posted by Big Shed

Thanks Martrix, I did give that some consideration and you're probably right.

I have been looking for some mild steel or stainless at that thickness, but no luck so far.

I'm a hopeless metal worker, so I'll stick with the ally for now till it gives me grief.

Does your overhead guard have dust extraction?

Perhaps you could put up some pics and sizes, particularly of how you mounted it?

Yeah, I think I used 3mm steel and lapped it down to about 2mm. Probably took me a good 5-6hrs to make.

My overhead guard does have dust extraction which I just hook up the vacuum to via a duct which runs along the overhead arm. The overhead arm just bolts on to the edge of the table with some 8mm bolts that I tapped into the table.

This is the only pic I have at the moment.

**Big Shed** · 21st October 2007, 06:16 PM

Thanks Martrix.

I might get my son to make me a steel riving knife, he is the metal worker in the family and when you see him use a file he makes it look very easy!

**gpsmith** · 22nd October 2007, 06:28 PM

Martrix,
I would be interested in the processes that you went through to make both the riving knife and the overhead guard. These are 2 thinkgs that I would like to have on my Jet supersaw. I have been told that it wold be a bigger than Ben Hur type of job.
Very big pictures would be a great help - It's on "to do" list which would probably mean 2015 at the earliest!

Regards,

**niki** · 22nd October 2007, 07:30 PM

Hi Big Shed

When you make the Riving Knife please consider the thickness according to the drawing (taken from HSE)

Regards
niki
Attachment 58540

**Big Shed** · 22nd October 2007, 08:33 PM

Originally Posted by niki

Hi Big Shed

When you make the Riving Knife please consider the thickness according to the drawing (taken from HSE)

Regards
niki
Attachment 58540

Hi Niki yes the riving knife I made is exactly the same thickness as the one supplied with the saw and conforms to the drawing you posted. What is HSE?

**martrix** · 22nd October 2007, 08:38 PM

Originally Posted by gpsmith

Martrix,
I would be interested in the processes that you went through to make both the riving knife and the overhead guard. These are 2 thinkgs that I would like to have on my Jet supersaw. I have been told that it wold be a bigger than Ben Hur type of job.
Very big pictures would be a great help - It's on "to do" list which would probably mean 2015 at the earliest!

Regards,

Hi GP, I did take progress pictures and will add them with the details to the thread I started on my mods to the TS My Table Saw "supermod" WIP........ . Hopefully I will have my mods finished before Christmas, but I have been too optimistic before.

How big a job it is I guess depends on your metal working abilities. Basically all I used was my MIG welder (a $99 GMC Arc welder will do it), an angle grinder, some taps for threading and a file for shaping.......and some Grey matter.

Originally Posted by niki

Hi Big Shed

When you make the Riving Knife please consider the thickness according to the drawing (taken from HSE)

Regards
niki
Attachment 58540

Hi Niki, I understand the theory in making the knife the same thickness as the teeth on a new blade (say 3.2mm or 3.0mm), but as the blades are sharpened, they progressively reduce in width and things will start to bind at the riving knife. Thats why I made mine around 2.5mm from memory. I don't have my calipers at the moment to measure it exactly.

**niki** · 22nd October 2007, 09:51 PM

Big Shed
HSE is...Health and Safety Executive (UK)

Matrix
Maybe they consider that if you start with new blade and make it as on the drawing, the sharpening will not remove so much...I'm far of being expert...

Regards
niki

**Big Shed** · 22nd October 2007, 10:38 PM

Thanks Niki, not immediately obvious to us Ockers

Acronymites is very pervasive these days

**Big Shed** · 22nd October 2007, 10:39 PM

Originally Posted by gpsmith

Martrix,
I would be interested in the processes that you went through to make both the riving knife and the overhead guard. These are 2 thinkgs that I would like to have on my Jet supersaw. I have been told that it wold be a bigger than Ben Hur type of job.
Very big pictures would be a great help - It's on "to do" list which would probably mean 2015 at the earliest!

Regards,

gpsmith, there is an interesting project for an overhead guard in Shopnotes #92.

**gpsmith** · 22nd October 2007, 11:14 PM

Martrix and Big Shed,
Many thanks for the directions and possible answers, it goes to show the value of this forum. When you have a question, there will always be at least one answer and or direction to follow.

Thanks again,

**Old Croc** · 24th October 2007, 11:06 PM

Hey Sheddy, I seem to rember reading somewhere that the slot in a riving knife should have a closed end so that if it was to come loose and touch the blade it would not pick it up and drive it through your chest. I think it was in these forums about 2-3 yrs ago,
Crocy

**Big Shed** · 24th October 2007, 11:13 PM

Originally Posted by Old Croc

Hey Sheddy, I seem to rember reading somewhere that the slot in a riving knife should have a closed end so that if it was to come loose and touch the blade it would not pick it up and drive it through your chest. I think it was in these forums about 2-3 yrs ago,
Crocy

Crocy, if the slot was closed end, you wouldn't be able to slide it in the clamp that holds it!

Unless I misinterpret what you are saying?

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