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Table Saw Invention

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Unread postAuthor: saefroch » Thu Mar 24, 2011 8:24 pm

About wet wood:

Some basic chemistry is in order here. The conductivity of distilled water is incredibly low. So also is the conductivity of wood, because it is completely nonpolar and does not allow any charges to migrate, like distilled water. The main chemical used in "pressure treating" wood is CCA, or Chromium Copper Arsenate. It is NOT that copper is conductive that allows wet pressure treated wood to trigger the SawStop. This is actually a sadly common misconception that metal-containing compounds are somehow conductive. Sodium is very metallic, and is a conductor, but Sodium chloride (table salt) is not. The copper is reacted with the arsenate ion but when it dissociates in water, these ions can migrate and allow charges to flow, similar to how the delocalized electrons in a metal can migrate to allow charge to flow. The migration of charges is what activates the SawStop.

The same goes for metal, as a conductor, it will allow charges to migrate like sweat can and trigger the SawStop.

boyntonstu wrote:A contractor cannot wait until wood dries to cut it.
That is very true, but it seem the inventor has already considered this drawback to the system. I agree with Killjoy that SawStop and your saw thingy (as we are now calling it) are both a partial solution to the problem.

But... there seems to be no end to poor Stu's trolling.
boyntonstu wrote:Can you think of any way to cut yourself using my saw when your hands are 12" away from the blade the entire time.
Can you think of any way to cut yourself on a table saw at all when your hands are 12" away? I find it appropriate to quote something Ragnarok already tried to tell you:
Ragnarok wrote:It doesn't matter, because the circumstances in which you might need to do such a thing under what are rather daft self imposed limitations are inconceivably slim.


Perhaps pride should be tempered with common sense.
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Unread postAuthor: boyntonstu » Thu Mar 24, 2011 8:30 pm

saefroch wrote:About wet wood:

Some basic chemistry is in order here. The conductivity of distilled water is incredibly low. So also is the conductivity of wood, because it is completely nonpolar and does not allow any charges to migrate, like distilled water. The main chemical used in "pressure treating" wood is CCA, or Chromium Copper Arsenate. It is NOT that copper is conductive that allows wet pressure treated wood to trigger the SawStop. This is actually a sadly common misconception that metal-containing compounds are somehow conductive. Sodium is very metallic, and is a conductor, but Sodium chloride (table salt) is not. The copper is reacted with the arsenate ion but when it dissociates in water, these ions can migrate and allow charges to flow, similar to how the delocalized electrons in a metal can migrate to allow charge to flow. The migration of charges is what activates the SawStop.

The same goes for metal, as a conductor, it will allow charges to migrate like sweat can and trigger the SawStop.

boyntonstu wrote:A contractor cannot wait until wood dries to cut it.
That is very true, but it seem the inventor has already considered this drawback to the system. I agree with Killjoy that SawStop and your saw thingy (as we are now calling it) are both a partial solution to the problem.

But... there seems to be no end to poor Stu's trolling.
boyntonstu wrote:Can you think of any way to cut yourself using my saw when your hands are 12" away from the blade the entire time.
Can you think of any way to cut yourself on a table saw at all when your hands are 12" away? I find it appropriate to quote something Ragnarok already tried to tell you:
Ragnarok wrote:It doesn't matter, because the circumstances in which you might need to do such a thing under what are rather daft self imposed limitations are inconceivably slim.


Perhaps pride should be tempered with common sense.


A transistor pops and then what will common sense and SawStop do to your fingers?

I would rather rely on a mechanical separation than an electronic sensing circuit.

Common sense!
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Unread postAuthor: MrCrowley » Thu Mar 24, 2011 8:35 pm

A transistor pops and then what will common sense and SawStop do to your fingers?

Your brakes will fail and then how do you stop your car?
The landing gear jams and then how do you land the plane?
The sail rips and then how do you make it home?

Do I really need to list more examples? People are injured or killed when things like this happen but there's no point worrying about whether they're going to happen or not all that you can do is prepare yourself. Treat a SawStop like any other saw, don't rely on the safety mechanism. Someone has already pointed that out before in this thread, did you not understand?

Edit: By the way, you still have my question about my avatar to reply to. Don't forget now.
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Unread postAuthor: boyntonstu » Thu Mar 24, 2011 8:38 pm

This a response from an expert on table saw safety about my thingy.

"Interesting stuff."


The second video showing kickback is similar to what happened to me, removing 5/8" off of my left-hand second finger. But instead of kickback, my father dropped the workpiece on top of the running blade (I had just passed the piece through the blade and he was ever leisurely picking them up off the outfeed table). And instead of styrofoam, the piece was approximately 3/4" x 15" x 36", and it winging by my head just like the styrofoam shown in the video. It ripped clean through a cabinet base and wedged itself in the open frame of the bandsaw 10 feet behind me."


In this example would the SawStop prevent this type of accident?

My saw blade is covered from above. You cannot drop anything onto the blade.
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Unread postAuthor: Insomniac » Thu Mar 24, 2011 11:03 pm

But if you're doing the right thing, you're not going to drop things on the blade anyway!

Your saw thingy can make certain types of accidents unlikely, yes. But you can still do something dumb and slice your fingers off. You HAVE to accept that, as it is a fact. You seemingly assume that people with a regular saw will do all sorts of stupid things, and yet will always follow correct procedure when using your saw!

And your argument of mechanical seperation vs electronic detection is absurd. In your saw you're using a mechanical means to keep yourself away from the blade. Which is great, because you can't hurt yourself if you're not in the way of anything that can hurt you.

However, you do the SAME THING when using SawStop! You follow procedure and keep mechanical seperation at all times. The difference is, that on the off chance something really unlikely happens... You lean over and slip, or you inadvertantly touch the sawblade for some other reason... There's a good chance SawStop will activate and save your digits.

SawStop is absolutely NOT a substitute for good safety practices. It is a last-defence, final measure to try and avert the worst possible situation.
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Unread postAuthor: JDP12 » Thu Mar 24, 2011 11:45 pm

Stu- yes your invention can prevent certain types of accidents, and the SawStop can prevent others. But every system will have weak points, no matter what. It's just a matter of what type of safety system you want.
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Unread postAuthor: Killjoy » Fri Mar 25, 2011 12:34 am

Ah I made a silly assumption and forgot what I learned in chemistry. Thanks saefroch, that was interesting about the pressure treated wood.
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Craftsman Radial Arm Saw Conversion - Upside down ripping

Unread postAuthor: boyntonstu » Fri Mar 25, 2011 1:57 pm

[youtube]http://www.youtube.com/watch?v=QEVXjJdDJtw[/youtube]

I removed the crosscut slide table for ripping.

The DeWalt table and my modified rip fence is used.

Notice the scrub brush hold down and the splitter/pawl safety.

I consider this to be a very safe way to rip.

The enclosed blade prevents kickback of anything falling from above.
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Unread postAuthor: Labtecpower » Fri Mar 25, 2011 2:10 pm

Maybe it is an idea to replace the brush with a vacuum cleaner?
In that way very little sawdust will spread trough your garage.
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Unread postAuthor: boyntonstu » Fri Mar 25, 2011 2:17 pm

Labtecpower wrote:Maybe it is an idea to replace the brush with a vacuum cleaner?
In that way very little sawdust will spread trough your garage.


The scrub brush is a safety hold down device.

I consider it a vertical featherboard.

I run 2 fans when cutting, a 24" overhead blowing out the garage door, a 20" floor fan blowing up at an angle to keep the sawdust away from me, and there is a vacuum cleaner sucking on the blade shroud. See the red tape holding the hose?

After playing in the garage, I use an electric leaf blower to tidy up the whole place in about 5 minutes.

Does it look safe to you?
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Unread postAuthor: Labtecpower » Fri Mar 25, 2011 2:31 pm

The vacuum cleaner looks pretty inefficient to me. If you're modifying a table saw, why not replace it :)

It looks pretty safe to me. You have to do really stupid things in order to cut off your finger.
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Unread postAuthor: boyntonstu » Fri Mar 25, 2011 2:44 pm

Labtecpower wrote:The vacuum cleaner looks pretty inefficient to me. If you're modifying a table saw, why not replace it :)

It looks pretty safe to me. You have to do really stupid things in order to cut off your finger.


The saw blade spins up from the table, opposite a table saw.

It is very difficult to capture all the saw dust.


However, it is not a problem for me.
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Unread postAuthor: saefroch » Fri Mar 25, 2011 5:07 pm

Why not replace your blowers with vacuum cleaners and have the mess already cleaning itself up while you're working? Placing the intake nozzle close to the side of the blade would catch most of it.

What happens in cases of kickback/throwback?

What happens if you touch the blade?
Keep in mind that this is just about as likely as touching a spinning lawn mower blade or snowblower auger...

What are the advantages of your design over using a SawStop backwards?
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Unread postAuthor: boyntonstu » Fri Mar 25, 2011 5:33 pm

[youtube]http://www.youtube.com/watch?v=sVpGi85HfnY[/youtube]

The problem with kickback, a demo.


An exposed blade is much more dangerous than a concealed blade in my thingy.

You cannot drop anything onto my blade.

I enjoy cleaning up the shop with a blower.

While cutting, I don't want the sawdust to touch me and I use the blowers for that purpose.
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Unread postAuthor: Gaderelguitarist » Fri Mar 25, 2011 10:37 pm

Stu, I noticed that your power switch is positioned above the danger zone of your modification. While I'm almost positive that you would have to actively try to make a dangerous situation for yourself while turning the saw on or off, wouldn't a more accessible switch be more safety friendly?

I realize that this would mean modifying a power tool that you might not necessarily want to mangle, but thats just my two cents.

And to those of you that don't know, kick back is terrible. It will send a piece of wood into you with plenty of force, enough to break a rib or two. Imagine if it was flung at an angle at your throat. Goodbye world of the living.

Nice elimination of that problem with the blade reversal. I'm curious to see a comparison of cut quality with your modification rip saw and a standard table saw.
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