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Riving Knife mounting dimensions - please share some info!

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Forum topic by steamngn posted 04-30-2020 05:09 PM 1320 views 2 times favorited 22 replies Add to Favorites Watch
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steamngn

12 posts in 351 days


04-30-2020 05:09 PM

Topic tags/keywords: riving knife table saw delta question

Greetings fellow LumberJocks!
working on a riving knife assembly for my Delta 10” contractor saw… and I’m up to making the mount for the riving knife itself.

I understand that there are multiple shapes/thicknesses etc….. what I am interested in are the dimensions for the “tang” portion where these knives mount.

Most of the knives I’ve seen have one drilled hole and one slot to drop over a stationary pin; I am curious if this hole and slot are similar dimension-wise and if the width of the “tangs” are similar as well.

so come on fellow wood butchers…. share some love… and dimensions! :-)

Andy


22 replies so far

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tvrgeek

1388 posts in 2656 days


#1 posted 04-30-2020 05:19 PM

You need to identify which “contractor” saw. Old one with a splitter, or new one with a riving knife.

Just make yourself a cardboard template. Don’t expect someone to have engineering drawings. Maybe someone can take a picture of theirs on top of some graph paper.

The knife should mount flush with the left side of the blade. That way different thickness will line up with the blade as the different thickness expand to the right.

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steamngn

12 posts in 351 days


#2 posted 04-30-2020 05:32 PM

Oops my bad! It is an older Delta 10” saw with a splitter. I can’t read the tag that was on the original cabinet but it is similar to the 36-650.

I am building the moving assembly to add a riving knife to this saw… and no I don’t expect engineering drawings. Sorry if it sounded that way! I am hoping some members will bust out the ruler and give me some dimensions. I don’t have anything as a base design to work off of and was curious if the mounting portion was similar or not.

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CaptainKlutz

4135 posts in 2501 days


#3 posted 04-30-2020 06:14 PM

Hmm?
1) Terminology: Does not read to me like you are making a ‘riving knife’?
A true OEM riving knife follows the motion of saw blade (up/down/tilt). Typically unless modifying the internals of your saw, standard mounting tab for blade guard was fixed height and only rotates. Attempting to use it alone, will not make a riving knife, it creates a splitter. You have to add a method of raising/lowering the splitter with blade height, to create a riving knife.

2) Splitter mounting tab:
A good reference for proper size of mounting tab for splitter on any saw, is the blade guard supplied by mfg. Many folks convert factory blade guard into a simple splitter, but cutting off the extra metal and plastic blade guard. If you don’t have one, then need to post saw PN and hope someone has one they can measure.

3) For additional education on making a riving knife, this existing thread might help you.
Another source of riving knife information is the aftermarket unit produced and sold by The Shark Guard. They are only company I know that produces a 3rd party splitter/knife for table saws.

Best Luck.

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

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steamngn

12 posts in 351 days


#4 posted 04-30-2020 07:27 PM

Hmm?
1) Terminology: Does not read to me like you are making a ‘riving knife’?
A true OEM riving knife follows the motion of saw blade (up/down/tilt).

ANSWER: I am indeed making a riving knife attachment that does indeed follow the motion of the saw blade arbor. Mechanical application of the blade-arbor arc and corresponding lever are mocked up and working.

2) Splitter mounting tab:

ANSWER: Since this is a completely new construction, I figured I would make the knife-mount match whatever the standard mount dimensions are – IF there is a standard, that is.
I realize I could make it whatever fits and have a knife made to match but figured it would be a good idea to at least see if there is any sort of commonality with these things.

3) For additional education on making a riving knife, this existing thread might help you.
Another source of riving knife information is the aftermarket unit produced and sold by The Shark Guard.

ANSWER: I actually sent off a contact to Shark Guard asking this very question – I’ve not heard back, at least not yet anyway. But figured I would also throw it out here as well.

I’ve seen plenty of comments/posts/attempts at adding a riving knife to older saws like this; most of them are usually tried/can’t/can’t be done… a few have been successful. None of them (that I’ve seen anyway) go into much detail about the mount itself.

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CaptainKlutz

4135 posts in 2501 days


#5 posted 04-30-2020 10:27 PM

Sorry, but the mounting tab is not standard between saws.
Next question?

Your new here, so here one last attempt to help:

runswithscissors did one of the most comprehensive sharing of pictures, information I have seen on LJ and he was successful on a Unisaw riving knife. Even offered to sell some of them a few years ago.
Here is a post with images: https://www.lumberjocks.com/replies/3033514
He has other threads on topic if you search for them.

There is also a couple posts hidden over at OWWM with images on how folks made a riving knife for various table saws too.

I don’t agree with your summary. Riving knife can be retro fitted to old saws, if you can afford the time and effort. Yes, There is very little information as tool designs are owned by OEM, and they don’t publish documents.
All the users that have reverse engineered older saws have/had visions of being able to sell the riving knife design to others, and never published hard details. No commercial designer would? Majority never sold any of the designs either; as mfg costs were more than most folks would pay, or the installation required serious machining work to saw itself (which not many are equipped to support). No where does that mean it can’t be done?

When you get yours completed, look forward to seeing your design documents so others can copy it.

Cheers!

-- If it wasn't for bad luck, I wouldn't have no luck at all, - Albert King - Born Under a Bad Sign released 1967

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steamngn

12 posts in 351 days


#6 posted 04-30-2020 11:15 PM

Ok Captain,
You’ve answered my question – there isn’t a standardized mounting. Thank you for that.
And I do appreciate the help!
Will be glad to post drawings and pics when done. I have a short video of the mechanical linkage but even short the file is large.
I guess I had it in my head that the mount would be the same for a given saw blade size…. sure wouldn’t be the first time I was wrong about something!
Andy

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runswithscissors

3128 posts in 3032 days


#7 posted 05-02-2020 10:11 PM

Steamngn: I an very curious to see what you come up with for your riving kinife. I eventually had parts cut out to make about 15 RK kits, and assembled and sold 10 of them. My enthusiasm waned as I began to realize how much tedious hand work was involved in putting one together—welds, drilling, tapping, yada yada. I did find that the water jet technology is much better than plasma—very clean cuts, and very precise. But I still had to cut out small pieces myself. I did convert a 14” bandsaw to cut metal (with a variable pitch bi-metal blade), which helped a lot. I still use that frequently.

Eventually I began to fantasize about having major parts die cast, to avoid all the welds, etc. Of course that is a very expensive process, and I chickened out. I still have parts for 5 kits, and wouldn’t mind selling the whole caboodle to someone to take it on, maybe improve and expand it.

I got very little feedback from purchasers, except for one time when I sent the wrong knife thickness to someone, due to the steel shop making me up a batch of the wrong gauge They made me a new batch of the correct ones at no charge. By the way, thin kerf knives should be 14 gauge, and standard or thick kerf are 12 gauge. No need for any precise measures down to thousandths of an inch or hundredths of milimeters.

I’m still using mine with good results and much satisfaction.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

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steamngn

12 posts in 351 days


#8 posted 05-04-2020 01:41 PM

runswithscissors:
I will gladly share. At first I figured I would make a simple wooden mock-up we’ll call 1.0 to test the viability of my idea and then move forward with crafting a final assembly:

This worked as expected, the left vertical arm of the parallelogram tracks properly and stays vertical. So far so good!

  • - HOWEVER….

I (usually) have access to a complete fabrication facility but due to the coronavirus issue (and having an extremely high-risk family member in the house) that ended that for the time being.

  • - SO…. since I haven’t been able to get to the shop or the steel supplier I actually began work on wooden mock – up 2.0 and have it 90% of the way finished. Version 2.0 is quite different than the attached version 1.0 image, being a complete sub-assembly mounted on a plate. This offers excellent rigidity and tolerance control for the arms, keeping the knife mount/arbor shaft position absolute. I will get a picture of 2.0 posted soon.

-AND THAT GOT ME THINKING:
could I reasonably engineer and fabricate this using only tools and materials that most people would have access to and ability to use…

-MAYBE.
I have been working on a steel production piece of version 2.0 using only basic hand tools and a drill press. No welding or custom fabrication. The lower parallelogram – bell crank arm is the most complicated piece of this design; making it out of plate brings challenges for pin mounts and pivot holes; thicker would be better. I am working on ways to improve final adjustments and simplify installation. I don’t think this design would need anything cast or machine-milled but only time will tell.
I have been keeping track of critical design elements and dimensions as I go so it shouldn’t be too difficult to draw up some engineering plans for this when done.

As I mentioned at the beginning of this post I have not crafted the knife mount itself just yet. I wasn’t sure if there was any commonality in mount design dimension-wise. Since that doesn’t seem to be the case I will settle on a pattern and move forward. The knife mount will have some micro-adjustment ability to set final Y-Z axis alignment of the knife with relation to the saw blade.
I’m getting there – As nice weather has finally come to the Northeast I have some outside projects that need to get priority but I will keep on this as much as possible.
Andy

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steamngn

12 posts in 351 days


#9 posted 05-04-2020 10:32 PM

I managed to find this early image of version 2.0 (Sorry it is sideways lol) you can see the plate has slots matching the arc of the arms to allow for carrier slides. These keep the arms against the plate. The plate mounts with the angle iron to the back trunnion carrier. The plate Itself mounts to the trunnion rod.

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Gus_Gus

6 posts in 369 days


#10 posted 05-11-2020 06:52 PM

steamngn really curious to see where you go with your riving knife retro fit. I am in the planning and research phase of doing the same to my unisaw.

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MrUnix

8408 posts in 3206 days


#11 posted 05-11-2020 07:15 PM

The design seems interesting, but pretty complicated for what it is IMO. If you want some inspiration, check out some of the riving knife mods for a Unisaw over at the OWWM site. Here are the parts involved in one of them:

Here is another similar design in action:

Lots more good stuff can be found starting here: Riving knife for Unisaw

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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Gus_Gus

6 posts in 369 days


#12 posted 05-11-2020 07:39 PM

Thanks for sharing Brad. Quite impressive.

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steamngn

12 posts in 351 days


#13 posted 05-11-2020 11:14 PM

Hey Brad,
I looked at that system; the difference with my design is the knife rides along a vertically-maintained plane, allowing the knife to stay further up the blade through the entire height adjustment.
In actuality the design is not too complicated – more tedious to engineer initially on paper. The 2.0 design allows for quite a bit of adjustability, and there are no complex or custom machined pieces…. at least that I have come across yet! ;-)

I will be a little delayed in getting the metal version cut, we’re getting the store ready to reopen here in NY state…. and that is involving a ton of preparation.

Stay tuned, I will keep on this as I can!
Andy

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kroginold

67 posts in 2055 days


#14 posted 05-12-2020 04:52 AM

Just food for thought: might buy a riving knife from SawStop or Powermatic and use this as a “standard”. They are likely to sell same design for a long time and have parts available. And I know my SawStop has a riving knife and 2 different blade guard/ splitter combo devices that use the same mounting. You could for instance get a riving knife and a blade guard with vacuum port for above blade dust collection.

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therealSteveN

7222 posts in 1581 days


#15 posted 05-12-2020 12:13 PM

Just passing through. steamngn, is that one pic of a wooden assembly what you are building, or just a prototype? I imagine you note the one Brad posted the pic of is all metal construction. That is the path you want to follow. The repeated hammering, and mini collisions of wood being cut running into a wooden splitter/RK makes all metal the only safe, long lasting choice.

-- Think safe, be safe

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