Why is a RAS dangerous?

[John Coloccia]

I've hear about RAS safety issues all the time, but no one ever gets into specifics. Honestly, I don't get it. Well, I get that it has a sharp, spinning blade, but almost everything in my shop has sharp, spinning blades...LOL. As long as nothing is lined up with the blade (which is generally a good idea on most power tools), what's the problem? 20 minutes of Googling just brought up more vague "RAS are dangerous" kind of links.

Maybe if I owned an RAS, or used one regularly, it would be more obvious to me. I do see that the saw wants to come towards you through a cut but I don't see that would be particularly dangerous unless you're standing right behind the saw, it knocks you over, and somehow nails you in the noggin.

Could someone give a quick overview of what makes RAS dangers unique from, say, a table saw?

[harry strasil]

People who don''t read instructions before using, and don't use common sense while using.

[Ken Fitzgerald]

IIRC...the dangers that are worried about happen when someone is trying to rip wood with a RAS.

[Bob Wingard]

RAS's aren't dangerous .. people who use them incorrectly are dangerous.

I've had one in my shop since the early 70's and on occasion, I was forced to use it for a ripping operation. THAT will get your attention, but it is not inherently unsafe to do so. Not my first choice for some operations, but then, that's why we have so many choices.

[dan sherman]

IIRC...the dangers that are worried about happen when someone is trying to rip wood with a RAS.

You mean cutting with the grain correct, not ripping (rough cutting) a board to length?

[Harlan Coverdale]

You mean cutting with the grain correct, not ripping (rough cutting) a board to length?

Cutting a board to length across the grain is called crosscutting. Cutting along the length of the board with the grain is called ripping. As has been said, ripping with a radial arm saw can be dangerous if not done carefully. But then again, most other things in the shop can be dangerous if not done carefully, too.

[Denny Rice]

I have never seen anyone hurt by a RAS. I really think its much to do about nothing. RAS are no more dangerous than any other power tool in the shop. I've had one for a long time, its not the most used machine in the shop but its handy to have when needed. The last time I used mine I set up a dado blade and cut series of lap joints into 2x4's to build a new tabletop frame for my workbench. (just like uncle Norms's.) I will say cutting lap joints on a RAS vs. a table saw is much easier because you are not cutting blind, you can see the cut line because the stock is flipped over.

[jim gossage]

Ripping is the main problem - I believe that even when done "correctly", it is inherently still a little more dangerous than with a table saw for at least 3 reasons. 1) the blade is hanging from an arm with several joints, and this allows the blade to twist relative to the feed direction, whereas the TS blade is relatively immobile, 2) the RAS post that the arm is attached to is somewhat in the way of your arm when feeding wood, and 3) there is much more blade exposed above the table compared to a TS, so that if the wood gets torqued, there might be a greater chance of your hand getting thrown into the blade. I have had a good quality RAS for 15+ years and a good TS for 8+ years. After my first couple of kickbacks on the RAS, I stopped ripping with it (about 13 years ago). I have never had a kickback with the TS and rib all the time. I am probably above average in my caution in the shop, but the RAS scares me for ripping.

[Rich Engelhardt]

Hello,
The Ryobi RA200 / RA202 can come apart on you during use.
That would certainly add a lot of excitement to one's life!

[Jeffrey Makiel]

The bad reputation comes from the fact that it can be so versatile. It can cross cut, rip, shape, etc. However, it only crosscuts and dado cuts safely in my opinion. And, it does these functions as safely as any other machine. The other functions (rip, shape, etc) are too much of a compromise and best done by other means.

-Jeff :)

[John Coloccia]

Thanks everyone for the input. I can see where ripping could be troublesome.

[Kevin Godshall]

The biggest danger I have had from my RAS...

After making mitered cuts, I "squared" the blade back to 90, using the stop adjustment, and made several "to length" cuts only to realize my square was now about 89 degrees....... grrrrrrrrrrrrrrrr.

Now I set it to 90 and never, ever, no never move it to to anything but cut exactly 90 degrees crosscut. (I don't even like to change the height).

Dangerous.

[Rod Sheridan]

One issue not mentioned with the RAS so far is the tendency to climb cut when cross cutting.

The RAS cross cutting is the only manually operated saw I can think of where the saw blade rotation and work feed are in the same direction.

(I don't own a SCMS however I believe the correct method is to pull the saw forward, plunge down, and then traverse backwards, this is to eliminate climb cutting).

You wouldn't climb cut on a shaper without a power feeder, yet you do it every time you cross cut when using a RAS.

That's why the proper cross cut blade for a RAS has a negative hook angle, to limit the tendency for the saw head to climb over the work.

There are methods of controlling this such as hydraulic dampers to limit travel speed, or using fully mechanized travel when cross cutting.

One of the most dangerous cross cut operations is the dado, they are aggressive and have a positive hook profile, which can easily lead to a climbing situation.

People are neither very strong, nor very fast. Having the saw head suddenly change from being pulled by you, to pushing you is something a person can't cope with, in the same manner that you can't stop a table saw kickback by holding the wood by hand.

The above problems, combined with having your head down there to look at the cut lines, or having your hand or arm on the table can have nasty results when the saw suddenly starts climb cutting.

Regards, Rod.

[Doug Shepard]

I think the main problem with ripping is with the tendency of the RAS to want to lift the wood, then bad things start to happen. I quoted this from a older thread, just cuz I'm too lazy to re-type it.


...
During my Jr. & Sr. year in high school I had a part time job at a local lumber yard. I can't tell you how many times I saw long (10-16') 2x10's or 2x12's kick back during ripping on a 12" RAS and go sailing out the door of the milling room. The few times the door was closed on one of these occasions, very large holes were actually made through the door. The old timers that worked there wouldn't let us kids near the thing for ripping, and after seeing a few of these incidents, I was happy to leave it to them.
...

[Fred Belknap]

I have one and it is retired to the barn. Some of the problems with the RAS was the blades that were available some years ago. They were mostly positive angle blades without carbide tips. They dulled rather quickly and the combination of dull blade and positive angle teeth would cause the saw to grab onto the work and it would run at you. If your hand was in the way it caused a serious injury. I have used mine to rip and crosscut ,also I used it to make molding. I used a wobble dado on it and it worked ok. I know two people who have been injured on a RAS, so I think it is good to use something else if you can. My biggest complain with mine was the inability to get it aligned and to keep it aligned. If I had room in the shop I would still use it sometimes. Shop is getting so that I might have to loose weight to get through it. :D

[Craig McCormick]

I built most of the furniture in our home with the use of a radial arm saw that I got for Christmas in 1979 when I was 15. I have never had a problem ripping boards.

AZCRAIG

[Chip Lindley]

I LOVE Radial Arm Saws! I have THREE Rockwells! (well, 4, counting the Craftsman I can't get rid of!) As with any power tool, *understanding* the machine is paramount to using it safely and successfully.

Using a 40T general purpose blade for crosscutting on a 10" RAS is not recommended! 60T with negative hook is mucho betta! 80T for glass-smooth finish cuts!

Ripping will always be hazardous when stock is bowed or twisted. Same on a RAS as on a TS! Hold-downs will keep a board from lifting. Anti-kickback pawls stop stock from kicking back! The blade guard of a RAS can be tilted downward to cover the blade but for the thickness being cut. The worst part of ripping with a RAS is the torrent of sawdust thrown directly at the operator!

Controlling the cut with a stiff forearm makes all the difference when cross-cutting or dadoing on a RAS. As with any machine, *get a feel for it!* A sports car does not drive like a big 4WD pickup!

In knowledgeable hands, and with forethought, a RAS can be a very valuable machine in the shop. Much more stable and accurate than most SCMS's.

[Lee Schierer]

The problem with Radial arm saws is that there are two distinct classes of saws out there. The old heavy Dewalt and Delta saws were solidly built and held their adjustments. To get costs down, many manufacturers went to less costly construction and started using aluminum instead of cast iron for frame components. This created more flexing in the saw structure which allowed things to move when the saw started working hard. The lack of precision for locking the arm and head in various positions leads to pinching of the boards when rip cuts are made which is a sure formula for kickback.

Sure all these things can be overcome with operator attention, but many users were not attentive so the RAS earned a bad reputation. The blade guard on my saw completely covers the blade so there is no chance of getting into the blade. I can even direct the sawdust away from me with the little rubber elbow that came with the saw.

I have one, I use it occassionaly but not for highly accurate cuts unless I spend significant time tweaking the alignment to insure the cut angle is correct. MOstly it collects dust except when compound angles are needed or when I have a set up on the TS I don't want to disturb and I need to make another cut.

[Greg Hines, MD]

I have only ever had one problem with a RAS, and it was during a ripping procedure. It picked up one of the pieces, and tossed it into a closet door, leaving a divot the shape of the corner of the board about 2" across and deep.

That said, it was a long time ago, when I was not as experienced, so I was not sure what I had done wrong at the time. I assume the piece got pinched between the fence and the blade.

Doc

[Cary Falk]

I don't think they are much more dangerous than any other power tool in the shop. There is something unnerving about the blade pulling itself towards you. It has it's limit at how far it can come at you but it is still a psycological thing. I used one when I was younger an never liked it. I don't have one now because I think it is dangerous to use tools you don't feel confortable with. I think it causes accidents just like using tools you are way too confortable with. I got bit last year by a harmless drum sander.

[Ronald Mancini]

I have a RAS set up 90 degrees to my table saw. I never use the table saw for cross cuts because I don't want to fool with any slider in a groove. The table saw does rip and angle cuts like it was designed to do. The RAS was used for the cross grain cuts. Now that I have a 12 inch compound miter saw in parallel with the RAS I leave the dado blade in the RAS and use the CMS for the cross grain cuts.

PS When doing dado cuts on a RAS cut from the end of travel to the stop to prevent blade climbing. Everything goes faster and smoother that way, but you have to be real careful of the exposed spinning dado blade, but you can make a guard.

[Scott Hildenbrand]

I remember back in shop class, when schools still had power tools.. I was using the RAS to cross cut some wood for a guitar body I was gluing up. Pulled forward to make the cut and it grabbed real hard and shut down from the overload.. My shop teacher came over, looked at the wood and then looked back at me and gave me a good open palm smack across the back of the head.

Lessons aren't learned the same way as they used to be.

Anyway.. I held onto the wood to keep it from jerking loose.. At Before it locked the tooth caught it and the whole thing jumped up before it shut down. :)

Still not 100% sure what happened to this day, but pretty sure it was internal wood stress that pinched it. That or I went too blasted fast.. ;)

[Peter Quinn]

I'm in the "Not ripping on the RAS unless I am stuck in the shop, the water is rising, it is the only tool working, and I have to make a quick battering ram to get out of the burning building quick" camp. I don't like the geometry involved, and i don't even care to contemplate taking my saw out of 90 degrees to set it up. You can use a power feed if you have a decent RAS, if its one of the El Cheepo's on the market over the last 30 plus years, a power feed would probably crush it, or at least flex the whole frame. Mine has a place to bolt a power feed.

On cross cuts that climb cutting thing is no joke. With the correct well sharpened blade, well tuned saw, careful operator moving at a controlled speed and a good fence, no problem. Move away from these requirements, and you have a big powerful motor and blade with lots of teeth racing at you quick.

A "worst case" scenario was described to me by a coworker as witnessed at one of his first cabinet shop jobs. A young rammy operator was cross cutting thick maple with a dull TS blade on an old DeWalt RAS with a lot of heel to the blade from not having been set up properly. This would be like ripping on a TS with the fence cocked 1/16" toward the back of the blade...not bright. He pulled the saw hard and fast into the stock, it rode OVER the board as it flexed the arm, shot out of the ways breaking the stop in the end of the head meant to prevent such problems (not maintained properly). So the saw still running hits the floor and starts dancing around as everyone in the vicinity runs for cover. It made shrapnel of the plywood floor. The kill switch was BEHIND the saw. Eventually someone got to the panel and killed the power, no one was injured. That sort of thing will wake you up.

What do I take from this? If one is not prepared to learn the rules of use for a RAS, to maintain the tool, and to operate it with the respect that should be given to any cutting machine of any sort, it is probably best to avoid the RAS. But they are not time bombs waiting to injure any user in random ways. They don't jump out and bite people unprovoked. They are a bit like dogs. If you abuse them they may turn on you, but with proper respect they can be your best friend.

[Joe Jensen]

The NUMBER 1 safety problem with radial arm saws is using a table saw blade on a radial arm saw. The tooth geometry for a table saw blade is such that the tooth pushes the wood down onto the table. If you use a table saw blade on a radial arm saw it will pull the wood up, and it will also tend to push the blade carriage out towards the user. Table saw blades have a positive hook angle. Radial Arm saw and Chop saw blades have a negative hook angle, often -5 degrees.

Circular saw blades are just as bad for RAS as table saw blades.

[Rich Engelhardt]

Hello,

But they are not time bombs waiting to injure any user in random ways. They don't jump out and bite people unprovoked. They are a bit like dogs. If you abuse them they may turn on you, but with proper respect they can be your best friend.
It's my understanding that the Ryobi models I mentioned above are or can be time boms.
Ryobi recalled them for a defect which would cause them to behave much as you describe, w/no apparent provocation.

http://www.cpsc.gov/cpscpub/prerel/prhtml06/06212.html

According to the above link, some 145,00 were sold.

[Matt Ranum]

I've only ever had one and its still in my shop and probably the most used tool there. A mid '90's Delta 10". I ripped with it once just to try it and decided it wasn't worth the hassle unless the table saw went down. The machine is tight and holds adjustments and has never seriously climbed at me, it did once get pinched when I cross cut a piece of Walnut with alot of internal stress in it and the board locked it self to the blade but the head unit never made dangerous movements. In my shop when it comes to dangerous tools my shaper ranks way higher than the ras.

[Denny Rice]

Ripping is the main problem - I believe that even when done "correctly", it is inherently still a little more dangerous than with a table saw for at least 3 reasons. 1) the blade is hanging from an arm with several joints, and this allows the blade to twist relative to the feed direction, whereas the TS blade is relatively immobile, 2) the RAS post that the arm is attached to is somewhat in the way of your arm when feeding wood, and 3) there is much more blade exposed above the table compared to a TS, so that if the wood gets torqued, there might be a greater chance of your hand getting thrown into the blade. I have had a good quality RAS for 15+ years and a good TS for 8+ years. After my first couple of kickbacks on the RAS, I stopped ripping with it (about 13 years ago). I have never had a kickback with the TS and rib all the time. I am probably above average in my caution in the shop, but the RAS scares me for ripping.

I agree with the ripping of wood it is probably more dangerous than using a table saw. At the same time I don't think a radial arm saw can replace a table saw in the shop. I think a RAS can enhance a shop that has a table saw because like I posted before cutting lap joints is much easier on a RAS than a table saw. It is also easier cutting rough lumber to manageable size with a RAS than using a table saw and miter gauge.

[Bruce Wrenn]

I think the biggest problem with a RAS is the "loose nut." You know, the one with his / her hands on the handle. Having grown up in a time when the first thing a house builder did was to set up "the DeWalt", I have seen and used plenty of RAS's. We've cross cut, ripped, made molding, all on the RAS. Find a copy of Curtis Erpelington's (sp?) video on making joints on the RAS. It goes against almost everything you have heard about the RAS. I invite anyone to show me how to make end cuts for a gable louver using anything other than a pair (left and right) RAS's.

[Dave Cav]

At one point this summer I had FIVE radial arm saws. A Dewalt MBF and MBC, a DeWalt 925 (all 9" saws from the '50s), a late model (late 90s) Delta 10", and an '80s Delta 12" turret saw. (But I'm one of those old arn lunatics...). Anyway, the 12" and the restored MBF are my daily drivers. I'm going to sell the 10" Delta, as I like the 9" DeWalt better. I'll probably sell the MBC once the restoration is finished, and I already sold the 925.

I started woodworking in the early '80s using a late 60s vintage Wards Power Kraft 10" RAS. I made the mistake of ripping on it a couple of times and after a couple of nasty kickbacks I got a small table saw for ripping, which was replaced by a Delta Contractor's Saw as soon as I could afford one. I use the big RAS for breaking down stock, and the little one for fine crosscutting and some dado and lap/bridle joint work. I also use them for making drawer sides; once I get the stock cut and the stops and dado set up I can cut a lot of drawer lock joints in a hurry.

[Mike OMelia]

I have never seen anyone hurt by a RAS. I really think its much to do about nothing. RAS are no more dangerous than any other power tool in the shop. I've had one for a long time, its not the most used machine in the shop but its handy to have when needed. The last time I used mine I set up a dado blade and cut series of lap joints into 2x4's to build a new tabletop frame for my workbench. (just like uncle Norms's.) I will say cutting lap joints on a RAS vs. a table saw is much easier because you are not cutting blind, you can see the cut line because the stock is flipped over.

I know someone who cut 3 fingers off with a RAS. Crosscutting. But to be honest with you, the guy was a few cans short of a 6 pack. Now he's a few fingers short too.

Mike

[phil harold]

all these things below are reasons I am not a fan of Radial arm saws

added to the fact that a sears RAS is garbage compared to an old dewalt it scares me more

and for the original poster who posted 20 minutes of googling must have missed "radial arm saw recall"
http://www.radialarmsawrecall.com/
and
http://www.cpsc.gov/cpscpub/prerel/prhtml06/06212.html



One issue not mentioned with the RAS so far is the tendency to climb cut when cross cutting.

The RAS cross cutting is the only manually operated saw I can think of where the saw blade rotation and work feed are in the same direction.

You wouldn't climb cut on a shaper without a power feeder, yet you do it every time you cross cut when using a RAS.

That's why the proper cross cut blade for a RAS has a negative hook angle, to limit the tendency for the saw head to climb over the work.

There are methods of controlling this such as hydraulic dampers to limit travel speed, or using fully mechanized travel when cross cutting.

One of the most dangerous cross cut operations is the dado, they are aggressive and have a positive hook profile, which can easily lead to a climbing situation.

People are neither very strong, nor very fast. Having the saw head suddenly change from being pulled by you, to pushing you is something a person can't cope with, in the same manner that you can't stop a table saw kickback by holding the wood by hand.

The above problems, combined with having your head down there to look at the cut lines, or having your hand or arm on the table can have nasty results when the saw suddenly starts climb cutting.

Regards, Rod.


Some of the problems with the RAS was the blades that were available some years ago. They were mostly positive angle blades without carbide tips. They dulled rather quickly and the combination of dull blade and positive angle teeth would cause the saw to grab onto the work and it would run at you. If your hand was in the way it caused a serious injury.

The NUMBER 1 safety problem with radial arm saws is using a table saw blade on a radial arm saw. The tooth geometry for a table saw blade is such that the tooth pushes the wood down onto the table. If you use a table saw blade on a radial arm saw it will pull the wood up, and it will also tend to push the blade carriage out towards the user. Table saw blades have a positive hook angle. Radial Arm saw and Chop saw blades have a negative hook angle, often -5 degrees.

Circular saw blades are just as bad for RAS as table saw blades.

[Sylvain Deschamps]

I sold my Craftsman RAS last month. It had been moved around, raised and lowered to clear through stairs and doorways so it was not adjusted. The gentleman who came to buy it said he had one 20 years ago and knew how to use it. We had just placed it on a piece of plywood ontop of a dolly in order to roll it to his truck. This is were I had an extension cord reading for a pre purchase test run of the saw. As I was busy rolling up straps, he placed a scrap piece 4/4 maple against the blade without adjusting it against the fence thus placing his left hand fingers between the scrap and the fence on the left side on the blade. Then with his right hand thumb he flicked on the switch upwards. Well I heard about this happening before but never saw it being done. The blade rose up onto the scrap piece and sprung forward towards him. Well, in an instictive defensive action he had the unfortunate reflex to hold on to the front of the boom but with his hand still twisted downwards. Now try to picture these hand positions... the right hand thumb is in a upwards motion flicking on the switch, thus positioning his index and major fingers underneath the boom at the front end of the rails and the left hand fingers are holding down on the projectile with the tips in front of the fence. This is what I now call "The RAS Two Hand Finger Pinch Position". Apon impact, he danced his way towards his wife waiting by the pick up, with his left hand fingers in his mouth and his right hand fingers under his left arm pit. His wife on the receiving end opened up her arms and cudled him as he was jumping up and down! Now this wasen't as gracious and as coordinated as a tango or the flamingo, but it sure was spectacular! Never having seen this dance before, I named it the " The RAS Two Hand Finger Pinch Position Dance". I should of had a camera, this would of been a $100K winner on AFV. Once we all were assured that there had been more scare than harm done, we all had a good laugh as he tried to verbalise his after action report.
Lessons learned : Pre operating adjustments and clearences are standard operation procedures, use them. It is also highly recommended to hold on to that handle as the switch is turned on with the other hand. I am not sure if this is in the book, but I always used a clamp to secure the projectile firmly against the fence.

[Paul Steiner]

The sears saws are much scarier that a solid dewalt or rockwell. I have a dewalt and I only use it for crosscuts and I am yet to have it climbcut. I am also very delibirate with all my actions and make sure my fingers are clear. Speeding through repeative cuts gets alot of people injured.

[Mike OMelia]

Originally Posted by Fred Belknap http://www.sawmillcreek.org/images/buttons/viewpost.gif (http://www.sawmillcreek.org/showthread.php?p=1215134#post1215134)
Some of the problems with the RAS was the blades that were available some years ago. They were mostly positive angle blades without carbide tips. They dulled rather quickly and the combination of dull blade and positive angle teeth would cause the saw to grab onto the work and it would run at you. If your hand was in the way it caused a serious injury.

Are you serious? I had no idea! Never seen one do that. So it could actually crawl the work piece forward?:eek:

Mike

[phil harold]

Originally Posted by Fred Belknap http://www.sawmillcreek.org/images/buttons/viewpost.gif (http://www.sawmillcreek.org/showthread.php?p=1215134#post1215134)
Some of the problems with the RAS was the blades that were available some years ago. They were mostly positive angle blades without carbide tips. They dulled rather quickly and the combination of dull blade and positive angle teeth would cause the saw to grab onto the work and it would run at you. If your hand was in the way it caused a serious injury.

Are you serious? I had no idea! Never seen one do that. So it could actually crawl the work piece forward?:eek:

Mike

I had this happen to me
afterwards you are always trying to pull the saw will pushing it back
sort of like an isometric exercise pulling whil not letting it come forward to fast

I also Had a dado walk forward too,
that was the last ime I used my crapsman ras
then I yanked the motor and got 100 bucks for it with the recall