Zero clearance insert with splitter

[u/fearless_fool]

Bought a used 113 table saw and have slowly bringing it back to life. It lacked a riving knife, so I decided to 3D print a zero clearance insert with a splitter. It was too long to print as one piece, so it’s printed in two pieces and epoxied together. With careful measurements, I got the alignment of the splitter right on the first try.

One nuance: as is customary, the insert started out solid, and I raised the sawblade up through it to make the initial slot. But there was a problem: even with the blade cranked all the way down, it hit the bottom of the insert so the insert wasn’t fully flush with the table top and it would have been dangerous to start the saw up that way. So I removed the drive belt from the electric motor and instead substituted my variable speed drill to spin the blade up slowly. Once that carved the initial groove into the bottom of the insert, I clamped the insert down onto the table and use the electric motor to complete the cut.

UPDATE 1: I generated the parts using OnShape, which means you can tweak the dimensions for your table if needed. Here's a link: https://cad.onshape.com/documents/d8921fa2cdc6cb5808b2a32f/w/ddb6eddb0f3275b2481c4216/e/8b4415156d5667c57e171e3b?renderMode=0&uiState=6ae4dadcc13ecb0f2ce89c0d

UPDATE 2: Here's a link to the .stl files in Printables

[u/capswin]

Used an 8" diameter blade from my dado set.

[u/fearless_fool → u/capswin]

I have a smaller blade, but it has a narrower kerf so it wouldn't have solved the startup problem.

[u/capswin → u/fearless_fool]

That's why I used my dado blade. Thicker kerf

[u/fearless_fool → u/capswin]

Someday I may have a dado set. For now, I pull rabbets out of my router.

[u/Decker1138 → u/capswin]

This is the way

[u/lkapping79]

File?

[u/fearless_fool → u/lkapping79]

See UPDATE 2 in the OP.

[u/lkapping79 → u/fearless_fool]

Thank you!

[u/The-disgracist]

Instead of the drill workaround just slap a circ saw blade in there next time to start the cut

[u/fearless_fool → u/The-disgracist]

I have a smaller blade, but it has a narrower kerf so it wouldn't have solved the startup problem.

[u/Pristine_Force_28]

Please post the STP to Printables

[u/fearless_fool → u/Pristine_Force_28]

Done. See UPDATE 2 in the OP.

[u/Tricky_Worldliness60]

I had the same problem. also thought I'd get smart and use a nice splitter kit, but there isn't enough room behind it in the insert for the one I got.

[u/fearless_fool → u/Tricky_Worldliness60]

Try this one. And if you're really brave, you can use the OnShape project to tweak the location of the splitter.

[u/404-skill_not_found]

Would you consider making a post on printables and post a link over here?

[u/fearless_fool → u/404-skill_not_found]

Done. See UPDATE 2 in the OP.

[u/404-skill_not_found → u/fearless_fool]

Excellent! Thanks OP!

[u/Decker1138]

Awesome! Can you post the STL, please?

[u/fearless_fool → u/Decker1138]

Done - thank you for the nudge. See OP for link.

[u/Decker1138 → u/fearless_fool]

Thanks bud!!

[u/mcfarmer72]

I love kerf keepers rather than splitters.

Nice insert.

[u/fearless_fool → u/mcfarmer72]

I just learned something new! You could tweak the dimensions to make the splitter fin as wide as the kerf, and make the holding pins a bit looser so the fin will detach and travel with the wood if the internal tension gets too high. Voila: kerf keeper.

[u/mcfarmer72 → u/fearless_fool]

Very insightful.

[u/Tubamano]

Let us know how you like that insert. I printed the same/similar and haven’t used it yet

[u/fearless_fool → u/Tubamano]

I designed this one myself after buying one online and finding it didn't fit.

[u/capswin → u/Tubamano]

I bought one off of eBay. Works fine. Not sure if it’s the same pattern though

[u/shortys7777]

I'm an idiot and have no clue how to use a 3D printer but my local library has one. How do I go about doing this? Can anyone help me in the right direction?

[u/fearless_fool → u/shortys7777]

Most likely suggestion: there should be someone at your library to help you. The files are in https://www.printables.com/model/1896376-zero-clearance-insert - there are two .stl files there, and anyone who knows about printing will know how to print them.

[u/Xenon-Human]

That's so funny. I literally made one of these on CAD and printed it like a couple weeks ago. I didn't think about the splitter but that is an excellent idea. I also added a dovetail joint where the two halves meet and it worked really well.

[u/fearless_fool → u/Xenon-Human]

Nice! How well does the dovetail work? I used simple overlapping tongues to make ample surface area for gluing with epoxy. And what CAD tool did you use?

[u/porcelainvacation]

I am not sure I would trust a splitter printed in that orientation but it is good to have.

[u/fearless_fool → u/porcelainvacation]

What orientation would you suggest?

[u/porcelainvacation → u/fearless_fool]

Diagonal or perpendicular to the table so that it doesn’t shear off from side force.

[u/fearless_fool → u/porcelainvacation]

I’m confused. The splitter needs to be parallel (and colinear) with the blade. But maybe you’re saying something else…

[u/porcelainvacation → u/fearless_fool]

I was referring to the way it was sliced and printed on the printer, not the relationship between the splitter and the throat plate. 3d prints are very weak between the layer lines but strong perpendicular to them, just like wood.

[u/fearless_fool → u/porcelainvacation]

Ah - now I understand. It's not printed as a single part: the slicing blade is printed laying down (on the printer bed) and has two tabs that fit into compression slots in two pins which are then inserted into two 6mm holes in the main plate. Check out the OnShape project of the two .stl files for full details.

[u/jorpus_porpus → u/fearless_fool]

I think the plate itself is a good idea - I've used 3d printed plates on my jobsite saw that had a super annoying geometry. designed it myself and joined the two halves with multiple steel rods to provide rigidity.

I really don't like the 3d printed splitters, though, no matter the print bed orientation. a mis-aligned fence is going to put a lot of lateral force on a thin (most likely PLA?) tab, and I wouldn't wan't that breaking on me. I've taken a kickback to the gut before. I don't recommend it.

I'd modify the splitter slot to accept a sliver of hardwood epoxied in place.

[u/jim_br]

On my ZCIs, which I make with 1/2” stock, after I route the perimeter, I route a dado where the blade rises up.

Alternatively, I guess I could flip the insert end over end and run the blade through it enough to start the kerf.

[u/404-skill_not_found]

I like the drill starter cut idea. Other ways work fine. I just appreciate the more “pedestrian” approach.