RAS safety I might be wrong ??

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Hobbyman2
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Re: RAS safety I might be wrong ??

Post by Hobbyman2 »

reible wrote: Sat Jul 03, 2021 12:46 am When I worked as a carpenters helper I got to do the ripping on the ras. Mostly because it covered you in saw dust. I don't recall any kickback issues and it was the only saw on site so it was used for most things that were not done with a circular "skill" saw. Most of these saws came with a cable and a magic box that controlled how fast it could move much like a seat belt, move fast and it locked.

My brother had a sears version and it didn't have the safety cable and was recalled, I think you sent the motor in and they gave you $$, maybe someone here did that and remembers the details???

My miter saw can work like the traditional "chop" saw by locking the head on the slides and I find this very useful. Of course the slides gives you a much wide cut with a smaller blade. And yes you bring the blade out then lower and cut while pushing in. They are designed to work with negative hook angle blades, much safer as they don't grab near as much.

If you have any doubts about how to cut with the saw you have it should be in the manual so read, understand and of course follow the instructions.

Ed
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LOL Its amazing how that thing about being the apprentice works . sears had a program where you could either receive a safety guard or return the saw motor for a cash refund but only "if" your model was listed , I called a couple years ago about the saw guard and was told the saw guard
offer was no longer available . the dust guard on most models are adjustable so you could tilt it forward to block the dust when ripping . many sliding miter box models also have a depth stop that many dont know exist .
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rogersk
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Re: RAS safety I might be wrong ??

Post by rogersk »

Hobbyman2 wrote: Fri Jul 02, 2021 9:47 pm
rogersk wrote: Fri Jul 02, 2021 2:57 pm The proper way to crosscut on a radial arm saw is to pull the saw through the board using a blade with a zero, or negative hook. The saw must be set up correctly, that is, the blade must be square to the fence and table, with no healing. The blade normally puts downward force on the wood, and also forces it toward the fence.

When ripping on the RAS, the proper way is to push the wood into the BACK of the blade. This is because there is no fence behind the cut to keep the board from being ripped out of the operators hands. A properly adjusted blade guard will hold the work down to the table, and the anti kickback pawl will keep the work from coming back at the operator, should the board try to close up on the exit side of the blade.

Sliding miter saws are operated differently. I can't comment on them because I have never used one. I have alot of expereince on a regular miter saw, just not the sliding type.

Also, I have read more than a few books on operating a RAS, and I have never read one that recommends pushing the blade through the wood while crosscutting.

Just my opinion.
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Thanks and I hope we can add a little more safety to your hobby .
first I would not agree at all with you statement , in fact that is very dangerous , not picking on you here because many folks do not understand , here is something to think about , the old RAS had adjustable kick back fingers that hung down off a rod , for them to work properly the saw had to be pushed through the wood , {not pulled} . I have heard some say the downward force from the blade keeps it against the fence when pulling the saw ???? there is some truth to that however like it was just mentioned there is also a climbing factor, push the saw through the cut and all that climbing danger goes away . you don't cut from the back side of a table saw ???? and you don't pull a power saw through a cut ???? here is something else to consider , when you pull the saw the dust goes down into the saw table because the blade rotation is downward , . when you push the saw through the cut the dust is lifted up and away into the collection system.

I don't know where to start with this. Perhaps I didn't explain myself very clearly. I'll try to make it simple.

Pulling the blade through the work is the proper way to crosscut on a RAS. Pushing the work through the blade is the proper way to rip on the RAS.

When crosscutting, the blade is turning toward the operator. If using a positive hook blade when crosscutting, the blade can grab (climb) and "run" at the operator. That is why a zero or negative hook blade is recommended. This can also happen if the saw is not adjusted properly. When ripping, the blade is turning away from the operator. This can lift the work off the table and kick it back toward the operator. The anti-kickback pawl (the bar with the little fingers on it) is there to prevent this. Also, when ripping, the blade guard is adjusted down to just above the work piece. This also helps keep the blade from lifting the work off the table and kicking it back toward the operator. I can show some photos on my saw later. I don't have time right at the moment.

The anti-kickback pawl is only used when ripping.

My earlier reference to using a miter saw is what some generally call a chop saw. I should probably have said power miter saw. Basically the same as a sliding power miter saw, but without the sliding part.
edma194
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Re: RAS safety I might be wrong ??

Post by edma194 »

I have not used a radial arm saw much but I was taught to pull the blade through the wood. I am surprised to hear you can push it.

I don't understand why pulling the blade through the wood is called a 'climb cut'. What is the 'climbing' part about?
Ed from Rhode Island

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RFGuy
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Re: RAS safety I might be wrong ??

Post by RFGuy »

edma194 wrote: Sat Jul 03, 2021 12:55 pm I have not used a radial arm saw much but I was taught to pull the blade through the wood. I am surprised to hear you can push it.

I don't understand why pulling the blade through the wood is called a 'climb cut'. What is the 'climbing' part about?
Maybe this picture will help. The diagram in the link below is for routers but the same principles apply to saws. You have to think about the rotation direction of the sawblade relative to which way the board (or saw) is being fed through the stock.

https://www.finewoodworking.com/2011/07 ... -naysayers
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Hobbyman2
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Re: RAS safety I might be wrong ??

Post by Hobbyman2 »

No problem , a lot of folks still use the saw the wrong way ,a few are missing fingers , in fact purdue has a website that describes the operation . and I totally disagree with their opinion as well , https://www.purdue.edu/woodresearch/wp- ... armsaw.pdf , with over 45 years respectively running one and still have my fingers I will keep doing it the way I was taught , watch the saw dust and decide for your self. pulling the saw in a cross cut is no different than pushing a piece of wood backwards through a table saw , only difference is the saw is on top and the wood is stationary not the saw blade . you are more than welcome to operate your saw as you wish . again when cross cutting by pushing or pulling the kick back fingers should all ways be used , it " will " stop the saw from kicking back in a pull or push cut .
pushing the saw forward will eliminate 99% of the threat of the saw kicking back and will keep the dust moving up and into the saw guard not between the table and the wood .
I know some people pull the saw into the cut so the dust does not interfere with them seeing the cut line , you should not have to worry about it if your saw is set up correctly , especially if you are using stops for mas producing the same length , My apologies , I did not start the thread to start a argument but to add safety to those using it , people have lost fingers running the saw as described in the purdue article and JMO the article should be revisited and corrected for safety issues . If you kick back fingers are set correctly you can only feed into the blade as seen in this video https://www.youtube.com/watch?v=ma3826fC7tU
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rogersk
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Re: RAS safety I might be wrong ??

Post by rogersk »

edma194 wrote: Sat Jul 03, 2021 12:55 pm I have not used a radial arm saw much but I was taught to pull the blade through the wood. I am surprised to hear you can push it.

I don't understand why pulling the blade through the wood is called a 'climb cut'. What is the 'climbing' part about?
When crosscutting on the RAS, if the wrong blade is used, or the saw is not in proper alignment, the blade can grab the work piece and move very quickly toward the operator and can actually "climb" up out of the cut onto the surface of the board. At this point the saw motor will stall and the blade will stop. Not good for the motor if the operator doesn't turn it off quickly. Often, though, the circuit breaker will blow.
rogersk
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Re: RAS safety I might be wrong ??

Post by rogersk »

Hobbyman2 wrote: Sat Jul 03, 2021 1:13 pm No problem , a lot of folks still use the saw the wrong way ,a few are missing fingers , in fact purdue has a website that describes the operation . and I totally disagree with their opinion as well , https://www.purdue.edu/woodresearch/wp- ... armsaw.pdf , with over 45 years respectively running one and still have my fingers I will keep doing it the way I was taught , watch the saw dust and decide for your self. pulling the saw in a cross cut is no different than pushing a piece of wood backwards through a table saw , only difference is the saw is on top and the wood is stationary not the saw blade . you are more than welcome to operate your saw as you wish . again when cross cutting by pushing or pulling the kick back fingers should all ways be used , it " will " stop the saw from kicking back in a pull or push cut .
pushing the saw forward will eliminate 99% of the threat of the saw kicking back and will keep the dust moving up and into the saw guard not between the table and the wood .
I know some people pull the saw into the cut so the dust does not interfere with them seeing the cut line , you should not have to worry about it if your saw is set up correctly , especially if you are using stops for mas producing the same length , My apologies , I did not start the thread to start a argument but to add safety to those using it , people have lost fingers running the saw as described in the purdue article and JMO the article should be revisited and corrected for safety issues . If you kick back fingers are set correctly you can only feed into the blade as seen in this video https://www.youtube.com/watch?v=ma3826fC7tU
The video you reference is the correct way to rip on the RAS. This is the method I have used for many years, and which I tried to explain in my previous posts. The Perdue pdf is also the way I crosscut on my RAS, and I believe it is the way it has been taught since the RAS was invented.

I appreciate you have over 45 years experience and still have all your fingers. I, too have over 45 years professional experience and have all my fingers. So, at this point, I guess we'll just have to agree to disagree.

For anyone just starting out on the RAS, I suggest reading at least one of the following books:

"How to Master the Radial Arm Saw" by Wally Kunkel

"Radial Arm Saw Techniques" by Roger W. Cliff (out of print but still available used on Amazon last I checked).
edma194
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Re: RAS safety I might be wrong ??

Post by edma194 »

rogersk wrote: Sat Jul 03, 2021 2:04 pm When crosscutting on the RAS, if the wrong blade is used, or the saw is not in proper alignment, the blade can grab the work piece and move very quickly toward the operator and can actually "climb" up out of the cut onto the surface of the board. At this point the saw motor will stall and the blade will stop. Not good for the motor if the operator doesn't turn it off quickly. Often, though, the circuit breaker will blow.
I don't understand the part about "climb" up out of the cut. How does the saw move upwards? If this were a sliding miter saw I could understand that happening because the blade is mounted on a lever arm, but on a RAS it slides on the rail at a fixed height over the table.
RFGuy wrote: Sat Jul 03, 2021 1:09 pm Maybe this picture will help. The diagram in the link below is for routers but the same principles apply to saws. You have to think about the rotation direction of the sawblade relative to which way the board (or saw) is being fed through the stock.

https://www.finewoodworking.com/2011/07 ... -naysayers
I understand the difference in the way they cut. However this is the first time I've considered how this affects routing. I have mainly used a push cut for routing, but occasionally the pull or climb cut. I'll want to look at both for future routing and check that difference. Tear out can definitely be a problem with some woods.
Ed from Rhode Island

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rogersk
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Re: RAS safety I might be wrong ??

Post by rogersk »

edma194 wrote: Sat Jul 03, 2021 2:45 pm


I don't understand the part about "climb" up out of the cut. How does the saw move upwards? If this were a sliding miter saw I could understand that happening because the blade is mounted on a lever arm, but on a RAS it slides on the rail at a fixed height over the table.
I've never had this happen on my DeWalt with it's heavy cast iron arm, but I did have it happen to me on a Craftsman I purchased in the 80's. The arm was basically sheet metal and the force of the blade coming forward too fast flexed the arm upward enough for the blade to just climb out of the cut. The motor stalled and the circuit breaker blew.

I purchased the saw new from Sears and it came with a one year in-home service policy. This is when Sears had there own service vans and would come right to your house. They initially setup the saw for me and it crosscut great. I began having problems when I started to rip with it--which was the reason I bought it. It ripped fine, but after changing back and forth from ripping to crosscutting a few times the saw would loose it settings and start to crosscut out of square and grab and run at me. I called Sears and they came out and set it back up for me. The service man asked me if I got the saw bound in a cut and I said no, it had been crosscutting and ripping fine up to then. When he heard I was ripping with the saw he said that was the problem. he said the saws had a problem holding their setup switching back and forth. He spent some time with me going over how to setup the saw so I could do it after the service contract ran out. I was quite disappointed, and sold the saw after just 2 years.

I bought the used 12" DeWalt 7790 from a cabinet shop going out of business because I had heard it was more heavy built and would hold its settings. And it has been perfect. I have never had any problems. I ripped all my sheet stock on it for about 18 years. I started using a Jet table saw in 2008 for ripping because I found it to be a little faster. Now that I'm retired, I am going to sell the Jet ProShop and go back to the DeWalt for ripping because the table saw takes up too much room. It has to sit in the middle of the room to use, whereas the RAS is up against the wall, ripping or crosscutting.
Hobbyman2
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Re: RAS safety I might be wrong ??

Post by Hobbyman2 »

rogersk wrote: Sat Jul 03, 2021 2:04 pm
edma194 wrote: Sat Jul 03, 2021 12:55 pm I have not used a radial arm saw much but I was taught to pull the blade through the wood. I am surprised to hear you can push it.

I don't understand why pulling the blade through the wood is called a 'climb cut'. What is the 'climbing' part about?
When crosscutting on the RAS, if the wrong blade is used, or the saw is not in proper alignment, the blade can grab the work piece and move very quickly toward the operator and can actually "climb" up out of the cut onto the surface of the board. At this point the saw motor will stall and the blade will stop. Not good for the motor if the operator doesn't turn it off quickly. Often, though, the circuit breaker will blow.
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Very true , in that situation the kick back fingers should stop the motor from advancing rearward . the motor may still stop and the breaker may still pop and you may have finger marks in the wood but it will not / should not advance rearward .
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