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I am looking to get started with RASes and am reading and learning all I can. (I will probably order the Kunkel book in the next week or so.) I have purchased a DeWalt 7739 but it needs a table and a complete adjusting/calibration - aside from me wanting to learn all about RASes before I start. Also, I am still in the market to purchase another and might pick one up soon. The 7739 I just bought has an 80 tooth blade but it is highly positively angled so before I start using it - or any other one - I will change the blade to a 0-degree blade.

I want to learn about climbing and have a few questions.

Maybe this question is manufacturer specific, but does the arm of a RAS 'float' in that column or is it captive? i.e., can the arm of a RAS lift up 'freely' and normally just rest on a lifting mechanism or is it locked?

When the saw climbs, does the blade run up on top of the wood being cut like a wheel? Does it warp or break the blade? Or does it continue the cut but much faster?

If I were crosscutting a piece of wood, say a 2x12, if it climbed early in the cut, does the climbing saw raise the whole arm mechanism in the back column? If the arm's column doesn't float in that back column assembly and the arm elevation is completely locked, do the teeth climb up on the wood, wedging the saw into the narrower distance of the uncut wood and throw all the adjustments out? Or, like I asked above, would it cut through the lumber much faster?

Every saw I have seen pictures of appears to have blades with positive-angled teeth. Regardless, have most/some/all of you RAS-users experienced a climbing RAS at some time or another? If it climbs, does it happen rapidly, i.e. too fast to react to? Or does it finish the cut, or slam the saw into the outer/distant stop of the arm before you can react? (I read in another thread that the blade cannot run up on the wood as I am fearing/imagining but then if not, why so much concern about it?)

Is it possible to say most RAS injuries are in a climbing incident? If not related to climbing, is there a particular scenario/mistake with a RAS that would account for most injuries?

A lot of stupid questions I am sure. When reading the wiki on RASes, it said many/most RAS mfgrs had eliminated them altogether or cut their RAS offerings down to one model. I would imagine it might have to do with injuries and as such, I want to learn the most common 'pilot errors.'. I will probably find my own share of mistakes to make but would like to sidestep a few if possible.

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The arm will not lift up on the post. Think of the blade as a turning wheel. if it was turning on the table, it will come towards you. The saw blade will try to come towards you as it cuts. You should use your arm to control the feed. On an underpowered saw, especially with a dull blade, it will stall the saw.
I did see a picture of a ras, with an aluminum arm, that was cracked. I think it may have been from a blade trying to self feed, with a dull blade, and it rolled up on the wood, breaking the arm.
I use a negative hook blade on my Red Star ras, and still have to control the cut speed.
If I need a real smooth cut, I put on a 90 tooth, + hook blade, and just control the feed rate.
I wonder if there is some reason not to cut in the opposite direction? I do it when cutting dados, with a std. blade. Pull the blade towards me. Move board. Push blade away from me. Repeat. No problem with this.

To counteract the self feeding, on a previous saw (old CM saw) I attached a bungi cord to the carriage, and to the wall behind the saw. It worked good.
 

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"climbing" is impossible

The saw, motor and arm are at a fixed height, so it can't climb over top of the work.:no:

Using a blade with an aggressive tooth angle WILL cause it to "self feed". Therefore use a blade with as close to a negative tooth angle as possible to reduce self feeding tendencies.

Always pull the blade across the work from behind the fence toward the front of the saw, keeping a stiff arm to resist any self feeding tendencies.

I have several RASs and use them for crosscutting exclusively. I use the table saw for ripping and some cross cutting with either a sled or a miter gauge with an extended fence. :yes:
 

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Maybe this question is manufacturer specific, but does the arm of a RAS 'float' in that column or is it captive? i.e., can the arm of a RAS lift up 'freely' and normally just rest on a lifting mechanism or is it locked?
The arm is captive and does not 'float'. It can be raised by being cranked up or down. It can rotate left and right by unlocking and moving the arm where its wanted.

When the saw climbs, does the blade run up on top of the wood being cut like a wheel? Does it warp or break the blade? Or does it continue the cut but much faster?
It may just feel like the blade is climbing on top of the wood and coming at you, but that just doesn't happen with an adjusted saw.

If I were crosscutting a piece of wood, say a 2x12, if it climbed early in the cut, does the climbing saw raise the whole arm mechanism in the back column? If the arm's column doesn't float in that back column assembly and the arm elevation is completely locked, do the teeth climb up on the wood, wedging the saw into the narrower distance of the uncut wood and throw all the adjustments out? Or, like I asked above, would it cut through the lumber much faster?
As mentioned, the arm is held in the back column, and doesn't allow free movement within the column.

Every saw I have seen pictures of appears to have blades with positive-angled teeth. Regardless, have most/some/all of you RAS-users experienced a climbing RAS at some time or another? If it climbs, does it happen rapidly, i.e. too fast to react to? Or does it finish the cut, or slam the saw into the outer/distant stop of the arm before you can react? (I read in another thread that the blade cannot run up on the wood as I am fearing/imagining but then if not, why so much concern about it?)
Ir only feels like a surging, that's easy to counteract.

Is it possible to say most RAS injuries are in a climbing incident? If not related to climbing, is there a particular scenario/mistake with a RAS that would account for most injuries?
Yes...having the fingers in the way of the cut, or contacting the spinning blade.






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My craftsman's ROS has an anti climbing mechanism built into the saw and can be set to 3 different levels ( A, B, C) of resistance so I do not worry about climbing. The mechanism also automatically retracts the saw. It is independent of the main saw because it has it's own power cord. The softer the wood the faster the cut (set at C). If I use a dado blade I set it at "A".
 

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When the saw climbs, does the blade run up on top of the wood being cut like a wheel? Does it warp or break the blade? Or does it continue the cut but much faster?
The most common issue is that the carriage is hard to control. If a "conventional" blade is installed in a RAS, it will tend to "climb" and self feed. Blades with a different tooth angle are available for RASs to minimize this issue.

When the blade starts to feed, a couple of things can happen:

1. If the saw has enough power, the blade will drive itself through the wood, toward the operator. If the saw has enough power to do this, it is difficult to control and the operator is likely to be surprised and unable to control the carriage. If it's a 3 HP saw, for example, the operator is suddenly trying to hold back nearly 3 HP worth of force with one arm, which is difficult.

2. In a few lighter saws, the arm may flex enough that the blade rides over the top of the wood. More commonly, the particle board/plywood/wood supporting table flexes down. This is more of an issue when cutting thin materials, such as 1/4" plywood.

3. If there is insufficient power and/or the table won't flex enough, the saw can stall.

The best advise I can offer is to use only saw blades intended for use on RASs and NEVER put a body part in the path of the blade.
 

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Discussion Starter #9
Thanks all for your thoughts.

I have wondered about what Pirate said, about running the saw backwards, away from me.

About two weeks ago I was running some small pieces of wood. (~ 10"*2"*1/4") through the router I had just installed in my table saw and after seeing two pieces sucked out of my hand and realizing that either I was too old and senile to react or maybe there was just a better way, I decided to feed them against the way the blade wanted to self-feed and things went a lot better.

Why is it not possible to push the saw into the wood to combat climbing?
 

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Long time RAS user on both rips and cross cuts (only saw I have) still in possession of all of my digits. I just assume it is going to self-feed on cross cuts and position myself accordingly. If it does, I'm ready. If it doesn't, no problem.

I've done push cuts before and haven't noticed any difference in the cut or the way the saw handles. Don't see any reason not to do it that way.
 

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Thanks all for your thoughts.

I have wondered about what Pirate said, about running the saw backwards, away from me.

About two weeks ago I was running some small pieces of wood. (~ 10"*2"*1/4") through the router I had just installed in my table saw and after seeing two pieces sucked out of my hand and realizing that either I was too old and senile to react or maybe there was just a better way, I decided to feed them against the way the blade wanted to self-feed and things went a lot better.

Why is it not possible to push the saw into the wood to combat climbing?
The problem I see, is the blade cutting from the bottom up, trying to lift the wood off the table. Buy scms's cut this way?
 

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What Pirate said. Pushing the saw away from you can potentially pick up the stock and it's far edge could lift over the fence. Then things get exciting. Any RAS instructions I've ever seen say to pull toward you.

After teaching shop for 36 years, the only serious RAS accident happened in the wood shop next to me. A 9th grader pulled the blade toward him but had his index finger in the blade path (That the table was painted orange on 6" on either side of the blade was something that escaped his notice). Fortunately, he realized his mistake before he cut his finger completely off - but he got halfway through and it was pretty serious. We had RAS's in all the high school and middle school wood shops and had a pretty good safety record with them; better than with the table saws or even the band saws for that matter.

I've had my lowly Craftsman RAS dig in and it's always stalled the motor (and scared the crap out of me!). I have a negative tooth angle Freud blade on it these days so that problem is minimized.

Bill
 

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Pirates comments are dead on for that matter. The thing is, if you put the right blade on, the issue becomes a non issue. I got turned off of RAS's while working at a furniture factory. One of my tasks was cutting parts to length on a RAS. Got so all I did was move the blank stock against the stops and start the cut.. from there on the saw plowed it's way through. Not bad from a production standpoint but sucks from a safety standpoint. The company was using the same blades for the RAS's as well as the table saws, roughly 15° hook angle.
I haven't got a RAS today and likely won't in my remaining lifetime but I do have a couple of sliding compound miters and the blades are a 0 +/-5° hook. Have not had a climbing nor a lifting incident with those. JMHO:smile:
 
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