Kickback Incident

[dlbristol]

Carbide blades do a pretty good job on aluminum but that stop rod is not aluminum. I know.

Yep! I have a 45 degree divot in my miter gage to verify that. Great thread, lots to learn here. I never thought about the very short pieces getting caught in the saw guard. I have seen them stacked under the guard as in Dusty's picture.

[robinson46176]

On my old saw all such operations were done with my big sled and the stop block was attached to the sled. "everything" moved together and the sled stopped its travel just as the cut was finished. It was then safe to just pull the whole assembly back away from the blade and lift out the cut-off or pick up any bits of scrap safely away from the blade. I also built it so that when the rear push bar passed the blade (only half way) the part of the blade on my side of the rear push bar was fully shielded.
Unlike using a miter gauge it is quite safe to hold on to the pieces on both sides of the blade unless they are too short. If they are too short for safe holding a quick clamp holding them to the rear push bar will keep them in place until you pull the sled back.
I simply have not "gotten around to" building a new sled for the TS-3650 yet. Not such a big deal since I have done little real woodworking yet in the new shop. Maybe I should get a "tuit" next week... I'll try to remember to take a picture of my old sled later today.

Here is a crappy old picture of my old tablesaw. Notice the stopped dado's in the wood table behind the saw. The back end of those dado's are cut out square to stop a miter gauge or my sled either one.
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Here are some even crappier pictures of my sled. I was using an old camera and forgot how many short comings it had. Tons of flash bounce and I had to just point it in the general direction since the light was low in the room and I couldn't see anything on the screen at all.
The runners on the bottom of the sled are just the right length to stop the sled at the right point. If I didn't have those stopped dado's to stop it (like my TS-3650 will be) I would run the bottom back far enough to put a stop cleat under it. I hope that makes sense...
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[johnmccrossen]

As a quick test, I cut 12 pieces of 3/4" thick x 1 1/2" wide plywood at 1 1/4" lengths using a stop block on a miter guage fence. All except the last few (which were held by the yellow pusher) were cut using the miter clamp to hold them. I stopped the saw after each cut. It took 4-5 seconds for the saw to stop before removing the cut piece or moving the miter back for the next cut. For the 1 1/2" wide stock, each cut cycle was about 12 seconds. I can not see where stopping the saw is a big time waster and it is the safest method. I also would not make a habit of cutting anything so short that it can't be held by or clamped to the miter guage. Other than that, this did not seem to create a kickback hazard for these small pieces, as long as the saw was stopped after each cut.

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[iclark]

As a quick test, I cut 12 pieces of 3/4" thick x 1 1/2" wide plywood at 1 1/4" lengths using a stop block on a miter guage fence. All except the last few (which were held by the yellow pusher) were cut using the miter clamp to hold them. I stopped the saw after each cut. It took 4-5 seconds for the saw to stop before removing the cut piece or moving the miter back for the next cut. For the 1 1/2" wide stock, each cut cycle was about 12 seconds. I can not see where stopping the saw is a big time waster and it is the safest method. I also would not make a habit of cutting anything so short that it can't be held by or clamped to the miter guage. Other than that, this did not seem to create a kickback hazard for these small pieces, as long as the saw was stopped after each cut.

okay, I'll ask the dumb question:
if this was on a SS, how much of that time was cranking the speed down to slow before turning it off and then back up to the cutting speed for each cycle of cut?

[JPG]

okay, I'll ask the dumb question:
if this was on a SS, how much of that time was cranking the speed down to slow before turning it off and then back up to the cutting speed for each cycle of cut?

I am guessing none! If yer SS has enough electrical power available it does NOT have a problem starting up at higher speeds. That being said, it IS a prudent thing to set it to slow speed after the last cut and before Moving it. The 3/4 HP motors have a more difficult time starting up at higher speeds.

[robinson46176]

OK, I'm going to throw this statement in here... I don't believe that there is good basic comprehension here as to the amount of lifespan being taken off of the Shopsmith (or any power tool) by constantly starting it up over and over again, especially something that that starts as hard as a Shopsmith does. Just because you do not see or hear an immediate effect doe not mean that you are not shortening its life. Many successive start-ups close together are far harder on it than the same number of start-ups spread out over longer time. Heat will build up in the plug, the power cord, the main switch, the centrifugal starter switch, the capacitor and the motor windings much more than just running. The more heat that builds up the higher the electrical resistance will build up which in turn generates more heat...
You should not hesitate to shut it down when needed for safety reasons but to "plan" to stop / start a whole bunch of extra times one after the other as part of daily use is in my opinion a poor plan especially when there are many other better options available.

[Ed in Tampa]

OK, I'm going to throw this statement in here... I don't believe that there is good basic comprehension here as to the amount of lifespan being taken off of the Shopsmith (or any power tool) by constantly starting it up over and over again, especially something that that starts as hard as a Shopsmith does. Just because you do not see or hear an immediate effect doe not mean that you are not shortening its life. Many successive start-ups close together are far harder on it than the same number of start-ups spread out over longer time. Heat will build up in the plug, the power cord, the main switch, the centrifugal starter switch, the capacitor and the motor windings much more than just running. The more heat that builds up the higher the electrical resistance will build up which in turn generates more heat...
You should not hesitate to shut it down when needed for safety reasons but to "plan" to stop / start a whole bunch of extra times one after the other as part of daily use is in my opinion a poor plan especially when there are many other better options available.

I agree with Farmer on this one. Starting and stopping a machine will kill the motor. If you notice production machines that must cycle on and off they usually do it with clutches instead of turning motors on and off.

I think we can over think and over kill this. The safest way would be using a sled and slidding the piece off the cut line after it has been cut free. The next safest in my opinion is the stop bar on the miter gauge but you would have to adjust it for every cut. The third and probably a safe way would be to use a stop block mounted either directly to the table (clamped) or clamped to the fence. However in all of these the operator must maintain control of both pieces of stock.

I would probably use either my Radial arm, my compound miter or a sled in that order.

Oh I forgot probably the safest way would be to use your Bandsaw. I'm finding more and more pluses to using my bandsaw lately.

[heathicus]

I'm glad that such a very constructive exchange of ideas all leading toward more safer methods of work has come out of my little injury. That is the reason I posted about it to begin with.

On my Craftsman saw, a big reason why I previously tried to remove scraps near the blade with it still running is that it takes about 30 seconds for the blade to stop spinning after hitting the switch. That's a long time when you're just standing there... waiting. When I built my miter extension and left the overhang so it would clear the cutoff, not having to turn off the motor and stand there and wait was one of my objectives. Because I know me and I know how impatient I get sometime. When the wound is healed and the memory of the pain has faded, I'll get in a hurry and standing there watching the blade spin as the seconds tick I'll decide it's OK to go ahead and clear the scrap out before the blade stops. I'll do it a few times and it will become more OK in my mind to do so. And as my comfort level doing this goes back up, so does the danger level. I need to maintain that fear (respect) of the blade. So avoiding that path by coming up with ways to move the scrap without putting myself in that situation of having to wait on the blade to stop is the safest course of action for me. I started with the miter extension. Soon, I'll build a crosscut sled.

Speaking of crosscut sleds, I got some good ideas from yours, Farmer, so thanks for posting them. The blade guard on the back side of the sled, and the stopped dadoes in your outfeed table that limit the forward travel of the sled are great ideas that I plan on incorporating.

[JPG]

. . .
Speaking of crosscut sleds, I got some good ideas from yours, Farmer, so thanks for posting them. The blade guard on the back side of the sled, and the stopped dadoes in your outfeed table that limit the forward travel of the sled are great ideas that I plan on incorporating.

Consider his 'todo list'. Add a stop which bumps up against the table front. Lot easier than building an outfeed table!

[heathicus]

Consider his 'todo list'. Add a stop which bumps up against the table front. Lot easier than building an outfeed table!

That is certainly an option. But I need an outfeed table anyway... Maybe the stop to begin with until I build the outfeed table.