Thread: Zero clearance insert

My insert for angled cuts can do anything from 90° to 45°. I made the insert originally at 90° and then lowered the blade, tilted it to 45° and raised the blade again. I think there may have been a sliver of material left between the 2 cuts but easily removed with a chisel. The reason I made a second 90° insert was because the fragile edge on the right of the blade was getting chipped away by doing some angled cuts. This was causing the gap to open up wider than the blade so therefore not giving full support to the material. I still use this one for angled cuts.

Insert.jpg

Never thought inserts could be pretty - well done Hodgo.

Do either of these videos give an insight on anything you may have missed when making your insert which prevents you raising the blade all the way up. Theirs seems to go all the way. Both a bit rough but they got the job done.
Video 1
Video 2

Originally Posted by Treecycle

Do either of these videos give an insight on anything you may have missed when making your insert which prevents you raising the blade all the way up. Theirs seems to go all the way. Both a bit rough but they got the job done.
Video 1
Video 2

Thanks for posting these links.

Some great ideas in Video 2. I have a Hare & Forbes table saw and the original riving knife is a poor design - very large (the table runs a 12 inch blade) and fixed to the table chassis, not the blade lift. This means that I have to take it off every time I want to use my cross-cut sled, so it ends up being left off all the time. On my zero tolerance insert, I have extended the slot and glued a thin piece of jarrah in to give a permanent riving knife with this insert. The use of the 16 gauge angle bracket in this video is something that I am going to copy - it is much better than what I have done.

Another good material for making zero clearance inserts is UHDPE. I buy small "fish scaling" boards from BCF or similar and cut these up for various purposes - they are cheap and about the right thickness. I originally bought them for making casting molds for epoxy resin / wood / hybrid pen blanks and knife scales, and a while back I made a zero clearance insert for my bandsaw. It works well. I haven't made one for the table saw using this material yet, but will give it a try when I get a chance.

Originally Posted by Treecycle

Do either of these videos give an insight on anything you may have missed when making your insert which prevents you raising the blade all the way up. Theirs seems to go all the way. Both a bit rough but they got the job done.
Video 1
Video 2

thanks Dallas

In the 1st video the guy has cut the slot shorter than mine and also reinforced underneath it after accidently splitting it, further impeding the travel of the RK, he also doesn't wind the blade up much more than 50mm as I see it and rips at about 25mm

the 2nd video he cuts a small triangular piece off the back of the RK to give it clearance as I have thought about doing if need be, I dont think there would be any adverse effect from doing this and it would fix everything

cheers
Hodgo

Hodgo, the cause of the problem seems to be that the size of ihe insert hole on the saw bench is too short on the outfeed side - a design anomoly that you and I will not be able to change. So we will have to work around it.

Posssibility 1: Is there space under the saw bench to add a short underbench extension to the zero offset insert? This could be a piece of 5mm ply and it would tie the two sides of the insert together. Something like this:

Zero Offset Inserts.jpg


Possibility 2: Can we use a stronger material for the inserts so that the tail out is less of a problem - eg HMWPE?

Thanks Graeme and BMKal
I've seen RK kits that attach to the upper side of the insert ,(Etsy I think), the idea didn't grab me tho, as I'd rather have the RK go up and down with the blade

I wondered were you could buy those chopping boards from, heard them mentioned as I do my research, BCF here we come

I've watched these utubes and several others and got all my inspiration from them, very good value,theres some good stuff on utube

I've thought about making the tangs that slip under the outfeed end much longer as I use the router to form the ends , the longest part of the RK slot is on the bottom of the ZCI probably very close to the back edge of the table

Hodgo

I've manufactured my own zero clearance inserts for years now. To secure them at the outfeed end I just machine a shallow cutout in the insert with a forster bit and glue in a thin "coin style" rare earth magnet. It is possible to buy these (e.g. McJings) in sizes to exactly match imperial Forstner bits - I usually find a 1/2" diameter x 2mm thick rare earth magnet is easily strong enough.

When the zero clearance insert gets sufficiently chewed up to need replacing, the magnets can be recovered and re-used.

I can take a photo later if anyone is interested.

I have used metal washers on my ZCI to hook under the table. Works well

Picture time....

I've found that 6mm MDF is exactly the right thickness for zero clearance inserts on my JET saw - no rebating around the edge or height adjusting screws required.

IMG20221108083613.jpg

Showing rare earth magnet. I also route a slot on the underside to thin the material down at the highest point of the blade. On a JET saw, even with the blade fully lowered, you can't sit the insert in fully before raising the blade up through it. Routing a slot before bringing the blade up allows the insert to sit flat in place.

IMG20221108083628.jpg

Stubby splitter, sanded to thickness midway between saw plate and tooth kerf. I have another zero clearance insert without splitter for shallow trenching cuts. One day I'll get around to finding someone with a CNC to make me lots of the basic blanks out of MDF or other suitable material !

Mr Brush's method using a stubby splitter would probably work for you Hodgo.




However, I am very reluctant to recommend it as it involves removing the riving knife from the saw. A big no, no in my book.

Originally Posted by GraemeCook

Mr Brush's method using a stubby splitter would probably work for you Hodgo.

However, I am very reluctant to recommend it as it involves removing the riving knife from the saw. A big no, no in my book.

The only problem is you can't do angled cuts unless you make an insert like this for all angles.

Originally Posted by GraemeCook

Mr Brush's method using a stubby splitter would probably work for you Hodgo.




However, I am very reluctant to recommend it as it involves removing the riving knife from the saw. A big no, no in my book.

I don't like the idea of the splitter/knife not moving with the blade at the same height

and I wouldn't use the saw without a RK, also a big no no in my book

one day, if I ever have to, I will,modify the RK to suit my inserts, after all its probably only a matter of trimming about 5mm off the back of the knife

A bit of a terminology thing...to me a riving knife specifically is something that moves up and down (and angles) with the blade, often a shark fin shape not protruding above the top of the blade. A splitter is any fixed thing that doesn't move with the blade, often sticks up way higher, and can be a pain to constantly remove when not required.

I'd love a saw with a riving knife, but most low-end saws (including JET) don't have this, and it can't be retrofitted in any way. I'm stuck with a splitter, but removed the huge and clunky contraption that came on my JET saw to replace it with the stumpy splitter shown on my zero clearance insert. Much more practical, and just as effective.

I believe SawStop saws have true rise/fall riving knives, but there you are paying for the safety features whether you want them or not.