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Zero clearance throat plate problem

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Forum topic by Thomas Keefe posted 02-23-2009 09:36 AM 2691 views 0 times favorited 7 replies Add to Favorites Watch
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Thomas Keefe

131 posts in 2873 days


02-23-2009 09:36 AM

Topic tags/keywords: zero clearance tablesaw

I made a new zero clearance throat plate for my Craftsman bench top table saw
and am having some problems with it. The first one I made from 3/4” oak and it
has always worked fine.

I made the new one from 3/8” phenolic sheet. It stands up on four allen screws
I threaded into the phenolic. I inserted a wire brad into the back of the plate
and cemented it in with epoxy to keep the plate from rising up in the back. This
is the same way the original plate worked.

After I raised the blade through the plate I removed the rip fence and turned the
saw on again. The first time the plate popped out and slid forward. I adjusted the
brad in the back to limit the amount the back could raise up and tried it again.
This time I standed well out of the way and turned the saw on again. This time
the plate popped out and was thrown across the room. I raised and lowered the
blade a few more times with the fence in place. After this, the plate stayed in place
for a few tests. However, I am uneasy using this throat plate until I better understand
the problem.

The variables seem to be:

1. The thickness of the material (only 3/8”); and
2. The stiffer material (phenolic vs. oak)

Does anyone have any idea what the problem might be? Thanks.

Tom


7 replies so far

View kiwi1969's profile

kiwi1969

609 posts in 2906 days


#1 posted 02-23-2009 11:34 AM

If it sits up on four posts then maybe it sagged after the phenolid was cut thru, pinching on the blade? Best guess.

-- if the hand is not working it is not a pure hand

View BigFoot Products Canada's profile

BigFoot Products Canada

697 posts in 2857 days


#2 posted 02-23-2009 01:58 PM

I have made the exact same plates for my Delta saw and they work fine. Make sure it is sitting level and lock your fence on top of it and raise and lower the blade several times. If you have done this already try removing it and turn it over. Use some sand paper and round off the sharp edges in the blade channel. Sounds to me like that is probably where your problem lies. The carbide teeth are catchin on it. Another option would be if you are using a thin kerf blade switch to a regular one which is just a fraction bigger anyhow and raise the blade through once again. That woul definitly solve it.

View CharlieM1958's profile

CharlieM1958

16242 posts in 3682 days


#3 posted 02-23-2009 03:37 PM

Try this: With the saw turned off, raise the bladethrough the plate and slowly rotate it with your finger to see if it hits the plate at any point in a complete rotation. It could just be one bad tooth on your blade that is catching the plate at start-up sometimes.

-- Charlie M. "Woodworking - patience = firewood"

View ajosephg's profile

ajosephg

1878 posts in 3025 days


#4 posted 02-23-2009 04:04 PM

Maybe the vibration of the saw causes the plate to shake around and touch the blade? So – options might be fix the vibration, figure out a more positive way of holding it down or increasing slot width (but that kinda defeats the purpose of zero clearance doesn’t it?).

-- Joe

View Thomas Keefe's profile

Thomas Keefe

131 posts in 2873 days


#5 posted 03-09-2009 07:59 AM

I have taken the advice about raising and lowering the blade a few more times and now it seems to
work fine. Although, it still makes me a bit nervous. Thanks for your help.

View Julian's profile

Julian

880 posts in 2990 days


#6 posted 03-09-2009 04:36 PM

What I do to my inserts is to put a screw in the side, and front. This way I can uncsrew it just a hair and it locks in very tightly to the top. Now when seasonal changes happen, I can adjust the screws to keep it snug.

-- Julian, Park Forest, IL

View Don Butler's profile

Don Butler

1086 posts in 2860 days


#7 posted 03-09-2009 05:26 PM

I’m very pleased that my tablesaw employs a hold down screw at the operator end of the plate. That way, if I make a plastic ZCI and it ‘galls’ a bit, I don’t have to dodge flying parts.
Thermoplastics will melt when cut under some circumstances and then a clean slot isn’t produced. It will have little globs of plastic in the cut that cause blade sticking. The advice to raise and lower the blade a few times is correct. It remachines the slot, clearing any bumps that resulted from heating the plastic to the melting point.
I don’t know if phemolic IS a plastic that will melt, some aren’t, but because of this phenomenon, I make most of my ZCIs of wood. Actually I like ply better that solid wood.

d

-- No trees were damaged in posting this message, but thousands of electrons were seriously inconvenienced.

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