Can laminated hardboard be used to make zero clearance throat plates for a table saw?

[dpb]

mtnbikeddie wrote: ...

Perhaps, but I've never seen one and have never heard of an incident the insert being "thrown".

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[J. Clarke]

Still, why tempt fate? The one time it happens it's gonna clip the mother-in-law in the back of the head and she's going to claim that you did it deliberately and there's the end of domestic tranquility for the next decade or so.

[dpb]

Some odds are so long as to make them essentially non-existent likelihoods. Out of all the PM-66's and Unisaurs that afaik have never had a single one w/ a insert plate lock mechanism it seems even if it were a occurring but rare event it would have surfaced sometime in the last 70-80 years or so given the number of opportunities. Yet I'd never even heard it broached as a possibility what more an event until a few posters up...

$0.001...

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[Larry Blanchard]

That was my reaction as well. My 1948 Delta is the only saw I've owned that had a clip in the back. The manufacturers must have since concluded that it added nothing to safety - and if the lawyers let them get away with it they were probably right :-).

[Lobby Dosser]

Why look on the downside? Upside is domestic tranquility forever.

[Morgans]

"dpb" wrote

Me neither. The only way it could happen is not having it secured while the initial cut through was being made, or if it was made so loose that it could rattle around in the pocket.

[Leon]

Blades do become non-flat, often during a cutting operation and this is especially likely with a think kerf blade if it gets hot. Then it starts to widen the insert slot and....

[Father Haskell]

Park the fence over the plate just to the side of the blade and raise away. Even then, stoop down to place yourself lower than the saw top and slightly to the side. Haven't had a plate thrown yet, but why take a gamble?

[Kevin]

You need some down pressure on the stock as you are feeding it, especially with smaller parts. I always get a chuckle out of the "as long as your saw is setup perfectly" as if every piece of wood behaves itself perfectly during cuts.

My most extreme example would be with my shop built tenoning jig that rides the rip fence, need a lot of down pressure to keep the stock from lifting in the cut, and if there's any flex your cut is too deep.

-Kevin

[Nova]

If you need enough pressure to flex the throat plate I suggest you have your blade sharpened.

[J. Clarke]

Also worth looking at the alignment of the fence--the blade should be drawing the work down, not pushing it up--if it's pushing up then the fence may be slighly misaligned with the back toward the blade so that the stock is getting pushed into the rising teeth.

[-MIKE-]

If you are needing downward pressure on a jig or stock, enough to bend a

1/2" MDF ZCI, there is either something very wrong with your saw or you are doing something very wrong.

[Kevin]

Okay I dare you or anyone else that's said I'm doing something unsafe to cut a piece of 1/2" MDF that is 14" long and 2.5" wide (The width of my insert on the right side of the blade), support it at the ends and then try to flex it with ONE FINGER.

Then try the same thing with 1/2" Baltic Birch ply. You can use your whole hand this time.

Then come back here and tell me I'm doing something wrong by using the one that doesn't flex.

-Kevin

[-MIKE-]

I didn't say you were doing anything wrong by using the one that didn't flex, but nice attempt at trying to change the subject without anyone noticing. :-p

What we're saying is that any operation (and specifically your tenoning technique) which causes you to push the stock downward to the table and subsequently, the blade, is not only bad woodworking technique, but very dangerous technique.

[Kevin]

I'm staying focused on the original point, that 1/2" MDF is a little flimsy for this application, rather than the example I used where it became evident to me that was the case. You may find yourself in a different situation where it comes into play. How much do you save using MDF instead of baltic birch ply? 10 cents? The OEM insert is steel and they ribbed the hell out of it. They could have made it out of plastic and saved some money, and you know that'd make the accountants happy. But they didn't. For some reason they thought it was important that it be very rigid and I've never seen a saw that came with one that wasn't.

I happen to have shot some video of a project and I have me in action using the jig. So here is a still frame of the horrible accident waiting to happen. Please cover the eyes of any small children or shop dogs so they don't have to live with the shock.

it look like I'm pushing down hard? Cause I'm not. But if that had been an MDF insert the cut depths would have been inconsistent.

Some amount of down pressure is a normal part of most operations at the table saw, you just don't think about it. Don't try running some

1/8" plywood through the saw without pushing down on it. It'll bounce like crazy and then almost certainly kick back. Whatever force you apply is NOTHING compared to the force the blade can generate into the table. It's just common sense to make the insert as rigid as you can practically make it. MDF is a poor choice.

-Kevin

[Jack Stein]

so your work won't easily slide. Also, either a toggle clamp or those handy spring clamps will be fast and effective.