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Radial Arm Saw Kickback

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Forum topic by cliftonpark posted 11-28-2017 01:49 PM 864 views 0 times favorited 34 replies Add to Favorites Watch
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cliftonpark

6 posts in 56 days


11-28-2017 01:49 PM

Topic tags/keywords: radial arm saws kickback rip sawing question

I am beginning to make stave bowls. I used my radial arm saw to cut the bevels using a rip blade. My first two bowls were made from pine. Worked out perfectly. Today I started to make a bowl from cherry and maple. I cut the bevels on the piece of 3/4” x ~15” cherry. No problem. When I tried to cut bevels on the 3/4”x 12” hard maple, the piece started chattering about halfway through and then kicked back after running the piece about 90% through. I cut off the bad end and attempted to run the piece through again to just take a shave cut (<1 />t have one. Does anyone have any suggestions or answers on what might be happening? Is it just impossible to expect this type of saw to do this type of cut on very hard wood?


34 replies so far

View UpstateNYdude's profile

UpstateNYdude

901 posts in 1822 days


#1 posted 11-28-2017 02:01 PM

I’m just curious, but why are you ripping these on a RAS? That’s one place where IMO the table saw is a bit safer. If you have to rip on the RAS I’d suggest a slow feed if the saw is under powered or possibly the blade is dull or full of pitch.

-- Nick, “I am always doing what I cannot do yet, in order to learn how to do it.” – Vincent Van Gogh

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cliftonpark

6 posts in 56 days


#2 posted 11-28-2017 02:19 PM

The reason I am using a RAS is that I don’t HAVE a table saw. The piece bucked and kicked when I even used a very slow speed. The rip blade I am using seems to be in pretty good condition, and has always worked great in the past (on longer pieces of walnut, cherry, pine). I was thinking of trying to use a crosscut finishing blade for this rip cut, but not sure. Kind of scary when it kicks and jams the blade. Also ruins the piece.

View OnhillWW's profile

OnhillWW

112 posts in 1071 days


#3 posted 11-28-2017 02:51 PM

You need to be VERY careful when ripping on a RAS as you have already found out. I would never do so w/o being sure the blade is in very good shape, i.e. sharp, true and balanced. Also make sure the anti kickback pawls are set correctly. And, finally you can clamp blocks of wood to the fence that are set to be a hair’s breadth higher than the thickness of the wood you’re working on; these can assist in holding the workpiece down and reduce chatter. Bevel or relieve the leading edge of each block to help guide the workpiece under it. Make an auxiliary fence if need be that is tall enough to assist with fitting the hold down blocks. AND never stand in line with wood being fed through the saw.

I once had a piece of pine kick back and fly 15 feet hitting a cinderblock wall and putting a hole in the block. Made my mind up then and there to get a table saw…

View GR8HUNTER's profile

GR8HUNTER

2966 posts in 551 days


#4 posted 11-28-2017 02:57 PM

sounds very unsafe to me try and use a buddy’s table saw or a band saw ….GOOD LUCK :<))

-- Tony Reinholds,Pa. REMEMBER TO ALWAYS HAVE FUN

View gargey's profile

gargey

862 posts in 614 days


#5 posted 11-28-2017 03:09 PM

Nothing

View Bill White's profile

Bill White

4807 posts in 3799 days


#6 posted 11-28-2017 03:17 PM

I had a RAS for many years before getting a TS. I bought Board Buddies for use in the ripping function. They work well. Still use ‘em on the TS.
Bill

-- bill@magraphics.us

View Harryn's profile

Harryn

57 posts in 2427 days


#7 posted 11-28-2017 03:47 PM

The problem here is that you are probably using the wrong type of blade in your saw. Radial arm saws should use a negative hook tooth blade for safety and avoid kickback. Table saws use positive hook blades. If you draw a line from the center of the hole to the teeth, a positive hook leans over the line, while a negative hook stays behind the line. These blades are not easy to find, but they are available on line. I have used my radial arm for almost 60 years, and I have learned thru experience.

View Fred Hargis's profile

Fred Hargis

4762 posts in 2332 days


#8 posted 11-28-2017 05:26 PM

Harry hit it on the head, you have the wrong blade. You could go to one with a small positive angle (negative hook angles suck at rip cuts), but a rip blade is just not very friendly on an RAS.

-- Our village hasn't lost it's idiot, he was elected to congress.

View MrRon's profile

MrRon

4496 posts in 3082 days


#9 posted 11-28-2017 05:50 PM

What make of RAS do you have? The consumer grade saws are not as rigid as the older professional models like the Delta. When pushing work into the blade and if the blade is dull, the arm may want to deflect, which would cause the wood to bind and kick back. Also what others said about using a negative rake blade goes. I don’t think I would use a blade with less than 40 teet;. a dedicated rip blade may be too aggressive.

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cliftonpark

6 posts in 56 days


#10 posted 11-28-2017 06:02 PM

I just checked the rip blade I am using. It is a Craftsman Professional 10” Thin Kerf 24 Tooth ATB Tooth Design 15 degree Hook Angle. Positive angle per Harry’s description. The finishing blade I was thinking of trying is a Diablo 60 tooth Miter/Table saw blade. There is no angle designation on the blade, but it definitely has a positive angle. I have been using this Craftsman RAS for 30 years, and only had one real bad kickback before when I ripped thin MDF with a general purpose blade. I had never before heard that an RAS used a negative hook blade. Thank you for that info. Do you know where on line I could find one?

View Fred Hargis's profile

Fred Hargis

4762 posts in 2332 days


#11 posted 11-28-2017 07:30 PM

Right here is a good one that’s fairly priced.

-- Our village hasn't lost it's idiot, he was elected to congress.

View pottz's profile

pottz

2230 posts in 823 days


#12 posted 11-28-2017 07:40 PM

i have a ras and use in daily but not for ripping,there best for straight 90 degree cuts.you said your blade has a positive angle you need negative hook as harryn said.i would never use the ras for ripping,your just looking for dangerous trouble!you may also want to make a jig of type to hold the piece firmly away from fingers and hands,so as to keep them!my advise save up for a table saw.good luck.

-- sawdust the bigger the pile the bigger my smile-larry,so cal.

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runswithscissors

2565 posts in 1864 days


#13 posted 11-29-2017 12:15 AM

I’m not sure what your problem is, but OnhillWW is describing what happens when you feed the wood in from the wrong direction with an RAS. Always feed against the carbide (i.e. against the rotation of the blade). My uncle put a dent in his garage wall by making that mistake.

It’s one of the main reasons the RAS got a bad reputation for safety. Though I have one, I never use it for ripping.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

View Smitty_Cabinetshop's profile

Smitty_Cabinetshop

14857 posts in 2457 days


#14 posted 11-29-2017 12:30 AM

Okay, he’s ripping with a RAS and many are convinced it’s the pinnacle of stupid to do so. If the best you got is ‘don’t rip with a RAS,’ save your comments please… it gets old…

Now, to try and answer the OP’s question… is it possible your fence isn’t dead nuts parallel with the blade, or that the piece is running skew towards the second half of the cut?

-- Don't anthropomorphize your handplanes. They hate it when you do that. -- OldTools Archive --

View LDO2802's profile

LDO2802

130 posts in 269 days


#15 posted 11-29-2017 12:38 AM

Is it an adjustable height radial arm saw? Can you lock the piece into place when ripping it? If so, cut it in several shallow passes. Sounds like it might not be powerful enough to hog through that heavy wood. Also, if you have a skill saw, I recommend building a drop in skill saw table that makes it act like a tablesaw. :)

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