Making a riving knife?

[Anonymous]

The riving knife on my SIP saw goes above the blade. This means I have to take it off completely for some cuts. Rather than modify the existing knife I was wondering what I could make a new one from (obviously metal but what sort of metal). Also where would I get the metal from?

Anybody got any ideas?

Cheers,

Dave

 

[TheTiddles]

Getting the thickness about right is important, if it's thin then steel (stainless or not) is really the only option, beyond two or three mm you could use ali or if it's for a dado head then engineering plastics would be fine. Depending on where you are, one of us with acess to a scrap bin could send you enough to make a couple.

Aidan

 

[Mr Ed]

I'd use aluminium, thickness to match the blade kerf, which is likely to be around 3mm or so.

Ed

 

[Steve Maskery]

Dave, I made mine. It's just mild steel, but it's not an ideal material.

Mine is for a Thin Kerf balde, so is just 2mm. It means it is easily bent, unfortunately. I don't know if Stainless would be stiffer, but it's something I'd look at..

The making is quite straightforward, you just need a hacksaw, some files and a drill, but it takes a while.

If you take WIPs I'm sure many here will be interested.

Cheers
Steve

 

[9fingers]

The riving knife on my SIP saw goes above the blade. This means I have to take it off completely for some cuts. Rather than modify the existing knife I was wondering what I could make a new one from (obviously metal but what sort of metal). Also where would I get the metal from?

Anybody got any ideas?

Cheers,

Dave

Talk to your local steel fabricators - they should have an offcut.
Or metalsupermarket if they have one near you.

If you are still stuck let me know the size and the thickness of the body of the saw blade you want to use it with and maybe I can get some for you.
Are you going to the Kent bash maybe?
Bob

 

[SeanG]

Dave, for mine I measured the blade thickness, knocked off a bit to get down to the first smaller standard thickness and then bought some SS from ebay, the bits I won were offcuts from a laser or water jet cutter.

Worked a treat.

 

[OLD]

I just got a new one from SIP and modified it did not cost a lot.

 

[jimi43]

I'd use aluminium, thickness to match the blade kerf, which is likely to be around 3mm or so.

Ed

Just a quick clarification of that Ed if I may be so bold.

The thickness of the riving knife must be somewhere between the thickness of the land (the body) of the blade and the thickness of the kerf.

e.g. if the kerf is 3mm and the land is 2.4mm then somewhere around 2.7-2.8mm would be the thickness of the riving knife.

If the riving knife is the same or larger than the kerf the stock will hit it even when cut...especially if it is slightly out of alignment...if it is thinner than the land of the blade then it won't work. The stock would pinch the blade before it would pinch the riving knife.

Once you have the shape you want bevel the front of the knife where the stock passes first...this guides the two sides of the stock cut if there is a slight misalignment.



Just use gauge steel. It is easy to cut with a hacksaw...file with a decent file and drill with HSS bits. I'd put a light coat of car spray paint on it too.

Jim

 

[newt]

I'd use aluminium, thickness to match the blade kerf, which is likely to be around 3mm or so.

Ed

Just a quick clarification of that Ed if I may be so bold.

The thickness of the riving knife must be somewhere between the thickness of the land (the body) of the blade and the thickness of the kerf.

e.g. if the kerf is 3mm and the land is 2.4mm then somewhere around 2.7-2.8mm would be the thickness of the riving knife.

If the riving knife is the same or larger than the kerf the stock will hit it even when cut...especially if it is slightly out of alignment...if it is thinner than the land of the blade then it won't work. The stock would pinch the blade before it would pinch the riving knife.

Once you have the shape you want bevel the front of the knife where the stock passes first...this guides the two sides of the stock cut if there is a slight misalignment.



Just use gauge steel. It is easy to cut with a hacksaw...file with a decent file and drill with HSS bits. I'd put a light coat of car spray paint on it too.

Jim

Interesting my knife has a tapered leading edge I assume to allow the wood to smoothly slide over.

 

[jimi43]

Exactly what I mean Pete

Jim

 

[Anonymous]

Cheers for all the info. If anybody does have some offcuts they could send me I'd be happy to cover postage.

I've taken some measurements and to make one riving knife I need a piece 22x17cm which is at least 2.4mm thick.

Cheers,

Dave

 

[9fingers]

Cheers for all the info. If anybody does have some offcuts they could send me I'd be happy to cover postage.

I've taken some measurements and to make one riving knife I need a piece 22x17cm which is at least 2.4mm thick.

Cheers,

Dave

Dave, Bit concerned that you might not have picked up the importance of the thickness.
It must be no more than the kerf of the saw (ie combined tooth width) and a bit thicker than the body of the blade.

I'd expect your spec to say Not more than x mm but thicker than y mm where x is greater than y.

I expect to be going to my local metal vendor sometime next week. I can get aluminium alloy or sheet mild steel there cut to nominal size.
Would you like me to get you some? Which material do you prefer?
I can't say what the prices will be but I always consider them to be a fair compromise on economy and convenience in selling small quantities.

I can then post it to you.

HTH

Bob

 

[jimi43]

22cmx17cm seems a bit um....big!

Jim

 

[big soft moose]

we've got some sheets of steel kicking about which are easily big enough - but i'm not sure on the width would need to check

 

[jasonB]

2.5mm is a standard steel thickness, if nobody can help try here

http://www.collegeengineering.co.uk/Mat ... lsheet.htm

http://www.ekpsupplies.co.uk/index.php? ... t&catId=82

Jason

 

[Anonymous]

Dave, Bit concerned that you might not have picked up the importance of the thickness.
It must be no more than the kerf of the saw (ie combined tooth width) and a bit thicker than the body of the blade.

Bob, I measured my existing riving knife. I then checked that this was between the size of the blade body and the kerf. I was quite suprised that it was and seemed a suitable thickness for the knife considering what has been said.

we've got some sheets of steel kicking about which are easily big enough - but i'm not sure on the width would need to check

Can you check please Pete? Cheers.

I expect to be going to my local metal vendor sometime next week. I can get aluminium alloy or sheet mild steel there cut to nominal size.
Would you like me to get you some? Which material do you prefer?
I can't say what the prices will be but I always consider them to be a fair compromise on economy and convenience in selling small quantities.
I can then post it to you.

Yes please. Based on the prices you've been giving for the router plates I can't imagine it to be too much either. Even if Pete can help out I'll just pass it on to somebody else on the forum for the same purpose (I'm sure others would be interested in making one). I'd prefer mild steel please.

22cmx17cm seems a bit um....big!

Strangely enough that's what I thought when I was looking on the bay earlier today. I obviously don't need most of the sheet as it will be cut out to the shape of the blade. I may well be able to get two blades out of one sheet.

2.5mm is a standard steel thickness, if nobody can help try here

Cheers Jason, will take a look.

Dave

 

[big soft moose]

its at work so i'll check monday - the sheets i have in mind are A2 size (they used to be the backing for info boards) so thats roughly 60cm by 120 - you'd get a fair few riving knives out of one of those.

 

[9fingers]

I expect to be going to my local metal vendor sometime next week. I can get aluminium alloy or sheet mild steel there cut to nominal size.
Would you like me to get you some? Which material do you prefer?
I can't say what the prices will be but I always consider them to be a fair compromise on economy and convenience in selling small quantities.
I can then post it to you.

Yes please. Based on the prices you've been giving for the router plates I can't imagine it to be too much either. Even if Pete can help out I'll just pass it on to somebody else on the forum for the same purpose (I'm sure others would be interested in making one). I'd prefer mild steel please.



Dave

Must be someone else quoting for router plates? I think the only pricing I've been mentioning is for motor capacitors.

Do you want to wait for the results of BSM - investigations? I'll possibly be going to my chap on Wednesday.

Bob

 

[big soft moose]

router plates is dibs h - here

 

[Anonymous]

Sorry. Too much metal on my mind. I suppose I should wait to see what pete has first. I'll let you know on Tuesday Bob.

Cheers for all the help guys,

Dave