ZCTP discussion

[LCHIEN]

I'm making some new ZCTP for my BT3000.

I know from past experience you can't cut a zero clearance kerf and then try to tilt your blade, the blade center of bevel is below the table top and the blade will pass to the right of the 90° slot. And everything binds up in a most unpleasant way when you try this (DAMHIKT).

Is there a reason not to cut a 90° by raising the blade through the blank ZCTP and then do the same thing at 45° - I am predicting you end up with two slots.

If you then cut away the material between the two slots then you'll have a partial ZCTP that you can bevel anywhere between 90 and 45, but you have zero clearance on the left when doing 90 and zero clearance on the right when doing 45. And small clearance for stuff to fall in on the in-between bevel angles. In any case it won't be larger than the half-inch wide slot in the metal throat plate that comes with the saw.

Thoughts???

[Black walnut]

As long as whatever it is you are using to make the throat plate is structurally sound with both cuts. I have never made a bevel one, just not a feature I use much. 90° and 45° together would probably work but 90° and 60° probably would not. 22.5° might also be quite valuable.

[LCHIEN]

I usually leave the ZCTP on as I hate having thin cutoffs disappear into the dust collector works. But when I need to cut a bevel, I usually forget that I have the ZCTP on and it quickly gets into a real bind. Haven't broken anything yet.

[LCHIEN]

New ZCTP.

Used the four hole mounting pattern

made more than one.

[dbhost]

I haven't started the saw with the ZCTP in place with a bevel set, mostly because I raise the blade, then set the tilt and figure out that the throat plate is in the way and back off first...

I get not wanting to suck bits and pieces into the dust collection system, but not sure you could get a bevel to work with a ZCTP since the position of the blade in regards to the opening will change with tilt and elevation....

[Black walnut]

I haven't started the saw with the ZCTP in place with a bevel set, mostly because I raise the blade, then set the tilt and figure out that the throat plate is in the way and back off first...

I get not wanting to suck bits and pieces into the dust collection system, but not sure you could get a bevel to work with a ZCTP since the position of the blade in regards to the opening will change with tilt and elevation....

Unless you change the bevel angle the blade will rise in a single plane retaliative to the throat plate. A plate is only good as a ZCTP for a single angle, possibly two, one being 90° and the other being a bevel, maybe. There will be just two slots a blade's width in the ZCTP.

[LCHIEN]

I tilted the blade 15° and raised it into the zctp. Results in a small opening to the right of the blade, which can be ok since thin cutoffs usually happen to the left of the blade.

I couldn't tilt the blade more than 30 degrees, not sure at this point why. And I will need to bevel the area for the riving knife. P.S. The blade is hitting something on the ZCTP past 30 degrees; it goes to 45 without the ZCTP in place.

Final thought - the slanted opening to the right is a chance for a thin cutoff to wedge between the ZCTP and the blade... bad.

[LCHIEN]

Now I had to make a box to store them



One of the wood ones is usable and the 15° bevel, but has several goofs. Four more are good ones. There's 2 more partially finished blanks. And A couple of plastic ones and a couple of metal OEM and dado plate ones.

[capncarl]

This post is not an endorsement or advertisement for a manufacturer. I recently purchased a zero clearance plate for my sliding miter saw from Colliflower that is the replacement plate with a snap and slide plastic insert for your saw to cut its slot. The snap and slide feature allows quick change of angle cut inserts without having to diddle with removing and leveling the whole part. I don’t have a lot of confidence in “toolless” applications but this looks like it may work well. Like I stated this is not an endorsement.

[LCHIEN]

How to make a custom zero clearance plate for your miter saw.

https://youtu.be/SHyscfmT_LE

[LCHIEN]

More thoughts on ZCTPs for the BT3x00 saws.

The profile of the replacement plastic ZCTP is kind of complex to make and machine and you have to keep some tight tolerances and trial and error to get it to sit flush with the saw main table. I have this thought for a vastly simplified ZCTP. In the picture below, on the left is a wooden plate that matches the plastic ones sold by Ryobi. It requires a rabbet down both long sides, a rabbet across the end and a second rabbet above that.



The one on the left is a prototype of a simplified ZCTP. As you can see, the sides are flush cut and the end requires just one rabbet (identical on both ends). Much simpler to build. And it eliminates countersunk screws in the very thin ends which distorts the ends and leads to their failure.

The lack of the extra rabbets causes some depressions in the table top.
Here is the fit of the full plate:


and here is the fit of the simplified plate:


The difference is, you have to use the four hole pattern, and you get some thin and shallow recesses circled in red, about 1/10th of an inch deep.
I think it won't matter, there are small depressions between the grooves on the top and the length is much shorter or thinner than any workpieces will be to fall in. Shouldn't be a problem.




Construction notes:
You still need to be pretty precise with this to fit. I dimensioned the hole locations from one corner - I found it pretty difficult to countersink for flat head screws. Better to drill the hole a little oversize (1/4") and counterbore .18" deep to cover a round head screw; gives more wiggle room.
The four-hole mounting bosses seem to be exactly 3/8" below the top surface of the table. What I did was get close with the router (13/32") and then use a small rabbet plane to knock off a little bit until I could slide a straight edge from the table to the ZCTP without catching.
The drawing indicates a small chamfer on the leading edge of the ZCTP; I don't have it on my pictures but I will put one there to ensure that workpieces don't catch as they are fed to the blade.
Don't forget, if you plan to gut the slot for the blade that the blade comes within 1/4" of the table top when lowered to the bottom; you need to route a groove leaving about 3/16" thick material over the blade if planning to raise the blade to cut the ZCTP so you don't trap the blade and break your belts!!!
The material I used was some laminate wood flooring someone tossed out. Half an inch thick, laminate over some composite wood stuff.