RAS cuting practices

[Nicolae Sipitca]

I just got my hands on an antique Craftsman RAS (103 series, about 80years old). It's in good working condition and i cleaned it a little too. will have to put on a new table top as the original one (yes, original, ....) is warped.
I've never used a RAS before and though i read the manual and what I could find on the net I am still a little confused:
I see it is being pulled towards the operator to perform a cut, and, since the blade is climb cutting, even with a negative rake blade it will theoretically pose some safety issues. would it not be more advisable to perform the cut in the other direction (pushing the saw into the workpiece, like on a SCMS)? Would this practice pose some other safety issues?
Also, does anybody use one of these to cut tennons? If so, what kind of jig do you guys use?
Thank YOU!!!
Nick.

[Joe Scharle]

It's always a source of great fun to watch someone push a RAS; from a safe distance of course! :cool:

Just like any other power tool, it's safetest to PUSH the wood into the cutter or PUSH the cutter into the wood. A RAS is cutting the kerf on the PULL stroke.
If you've ever had a router run away in a climb cut, you should be able to visualize what a 10-12" blade powered by a bigger induction motor would look like.

As for cutting tenons, all I ever use is a stop block.
Good luck and always be careful...

[Nicolae Sipitca]

it's actually a 9in RAS, will most probably receive a 8 1/4 or 8 1/2 in blade.
Should I deduct that pushing the blade into the work is an unsafe / unacceptable practice?

[John Lifer]

Uh, YES! The saw will PULL the wood into the fence. Forget the climbing worry. Great crosscut saw. I'm still leary of ripping....

[Myk Rian]

You pull the blade into the cut. Period.
The negative tooth blade is used for just this reason. So it won't climb on you.
The 103 series saws are from about the 1960s. Is it the type with a worm gear drive? Like this one on the VM site.
http://www.owwm.com/photoindex/images/3065-C.JPG

[david brum]

Nicolae,
If you're having serious issues with climb cutting and you're using a negative hook blade, you might need to tighten the roller bearings on the yoke. The yoke/ motor shouldn't slide too freely inside the arm. It should take around 5 lbs of pressure to move it. The bearings should be on some kind of cam, so you can adjust the tension. You'll have to take the yoke/motor off the saw to do the adjustment.

[Nicolae Sipitca]

Nicolae,
If you're having serious issues with climb cutting and you're using a negative hook blade, you might need to tighten the roller bearings on the yoke. The yoke/ motor shouldn't slide too freely inside the arm. It should take around 5 lbs of pressure to move it. The bearings should be on some kind of cam, so you can adjust the tension. You'll have to take the yoke/motor off the saw to do the adjustment.


It does look exactly as the one in the picture. I did not put it through paces as the table was warped, but, I did try it for one cut in a 2x3 pine and it did pull into the work, nothing too bad but, I can imagine that getting much worse if you try a harder / thicker piece. I imagine the dull blade has something to do with this but still, ....
I also tied one cut by pushing the blade into the work (the way I imagine it would work on the table saw), the workpiece was clamped to the table; it felt quite different (and in my personal opinion more safe; but I don't know much about wood working, new to this whole shebang).

The bearing on the slide rods are adjustable, right now I would say it takes 3-4 pounds of pull to move the saw.

[John McClanahan]

I did push cuts on my Craftsman saw for many years without any issues. Then I learned that that way is wrong and dangerous. :eek: I still prefer to cut pushing the saw.

It is very important that the saw is tracking "true". Craftsman radial arm saws have a long history of not holding their settings very well.

John

[Rick Potter]

Nicolae,

Google 'Wally Kuncle' or 'Mr. Sawdust'. He wrote a book on Radial Arm saws that is considered by many to be the 'bible'.

Also google 'Beachside Hank' videos. Hank Metz made several interesting videos about RAS's. He also has several pictorial postings on this site.

I also suggest you google 'Radial arm saw safety', there are a lot of suggestions there, many good.

That should keep you busy, do your homework. This tool, like any other, is safe when used properly, but there are many who misunderstand it and misuse it.

Rick Potter

[Alan Wright]

David, Glad I read your post. I got a used Delta/Rockwell vintage RAS last year and the blaed that came with it was a very nice old industiral Delta blade and sharp as could be. It wasn't however, negative hook and I had some climbing issues. I bought a Forest blade specific for this saw (5% negative hook). There is less climbing, but still some. The motor assembly slides perfectly with no slot. Perhaps I need to Tighten it up. I'll check owners manual to the how to.


Nicolea,,, sorry didn't mean to highjack the thread. Alan

[Myk Rian]

I also tied one cut by pushing the blade into the work (the way I imagine it would work on the table saw),
You did this after it was recommended not to?
I suggest you sell the saw right now, and try something else.
I see danger in your future.

[Nicolae Sipitca]

You did this after it was recommended not to?
I suggest you sell the saw right now, and try something else.
I see danger in your future.

i tried that before i posted, ......
i hope no more danger in my future, had enough as it is, ....

seems like the local library has some books on the - time for some reading

p.s. can somebody explain the phisics of how pushing the blade into the cut would create a dangerous condition? if this is not too much to ask, of course. not trying to be an ass but i like to understand things, not just take them for granted like a robot.

[Myk Rian]

The problem is pulling the saw out, and positioning the wood behind it.
It just is not a safe thing to do.
Not to mention the sawdust getting trapped in the cut.

[Nicolae Sipitca]

i don't mean to be an ass, i really have to reiterate this just in case some of you feel like this.
i can't get to the library before weekend and curiosity pushes me to "fogure this out asap", i know, curiosity killed the cat, ...

are you referring to the motion of returning the saw to the initial position?
The way I did it was like this: clamp wood to the fence, push the blade through the cut. stop blade, unplug saw, unclamp wood, inspect the cut.
I was trying to see if I can cut a tennon on this thing and figured I do not need to pull out the saw since the cut goes all the way.
I guess i'll read some, build the table for it and give it another try on the weekend.

[david brum]

Alan, it helps a lot. There will always be some tendency for the blade to climb, though. This is especially true when cutting thicker material. I still occasionally stall my RAS when I'm cutting over 1 1/2 if I don't consciously slow the cut.

[Myk Rian]

Nicolae

I restored a DeWalt RAS, and in the process learned everything about it. Before that I was terrified of them.
After the restoration, learning process, and actually using it more than my table saw, I can, without a doubt, say that pushing the blade into a cut is not the way to do it.
Just don't do it. I'm done commenting on this subject, as my next post would get knocked down by the mods.

[John McClanahan]

p.s. can somebody explain the phisics of how pushing the blade into the cut would create a dangerous condition? if this is not too much to ask, of course. not trying to be an ass but i like to understand things, not just take them for granted like a robot.

I would like to hear the answer to this, too.

John

[Myk Rian]

OK. One more.
It has a tendency to lift the stock. Clamped, or not.

[Stephen Cherry]

For the physics part, my guess is that the problem while pushing is that the blade tends to lift the workpiece off the table, in addtion to creating a safety issue by having the blade out in the open and maybe turning while you are positioning the wood.

I'm also a new radial arm owner, although I did have one many years ago. For the climb cut, as David recomends, I would recomend tight bearings. You want some resistance and minimal movement during the cut.

For tenons, I would consider tilting the blade down, parallel with the table, and cutting the cheeks from the left side, board face down, maybe even with two blades appropriately spaced out to cut both cheeks at the same time. It may require a supplemental table with a groove for the arbor nut. THis is not a climb cut, but you would need destaco style clamps to hold the piece firmly in place. I WOULD TAKE AN HOUR AND BUILD A BLADE GUARD TO DO JUST THIS ONE CUT. Start with cutting 1/8 inch, see how the machine feels, and work your way up from there. If the saw is sufficiently rigid and powerful, you should be able to cut full depth cheeks at the same time. I would consider this an advanced use of this saw, and would not recomend it if you are not comfortable fabricating jigs using clamps.


EDIT- here's one of our local heros doing this cut on the other side of the blade, and pushing so that it's not a climb cut
http://www.youtube.com/watch?v=kSSROQBPhQo

[HANK METZ]

Congratulations on your acquisition of a radial arm saw, do me a favor, resist the impulse to take it through the paces and don’t play with it any more until you have gone through the operators manual cover to cover and have fully calibrated the saw after you have replaced the top.

As to your question about push vs. pulling the saw through the work, all radial saws are designed to be parked fully behind the fence, this is a safety aspect that you want to follow. Pulling the saw out to the extreme, positioning the work behind and plunging it through the work poses an unnecessary risk, is an inefficient work practice, and will not provide a “better” cut. The selection of a sawblade can be simplified somewhat by only using the smallest blade that will do the work at hand, a triple chip blade 8” in diameter will do most all jobs in the woodshop, even if the saw can swing a larger blade. In use, the blade, when crosscutting, is not allowed to fully exit the cut, but is returned to the parking area awaiting the next operation.

Tenons are a prime example of what a radial saw excels at, this video shows how (http://www.youtube.com/watch?v=kSSROQBPhQo).

For a more detailed project undertaken on the radial saw, this video shows that (http://www.youtube.com/watch?v=GU2fEdGwD84).


- Beachside Hank
Improvise, adapt, overcome; the essence of true craftsmanship.

[Lee Schierer]

Cross cutting on a RAS takes a bit of getting used to. You have to push as you pull the saw into the cut. It is best to practice with some soft pine to get the hang of how it behaves. You will want to pull the blade into the cut. This puts down force on the wood to keep it tight to the table and tight to the fence. It also reduces the tear out on the top surface. You will want to cut a kerf about 1/8-1/4" deep into your new table so the tips of the teeth clear any wood you want to cut. A RAS can be a useful tool in the right hands. It can also be dangerous.

Ripping can be done safely if you adjust the saw so it aligns parallel to the fence when you rotate the housing for a rip cut. Then you must adjust the guard properly and use the anti kickback pawls. You will be pushing the stock into the blade in a conventional cut, not a climb cut when ripping. Regard less of whether you are using a RAS or a TS never stand in the line of fire where a kick back will go.

Your older saw will not have the improved blade guards that later models had.

As others have mentioned. Before you proceed, read about how to use a RAS and understand how it works. A good tune up is an absolute necessity to insure the saw is properly aligned. You will need to repeat these check from time to time as it will change.

[John McClanahan]

Well, I'm not trying to argue, but I have never had the board try to lift while push cutting, and I don't clamp anything down. If the saw is set correctly, the blade is pushing the board down and into the fence.

John

[Jerry Wright]

I would like to hear the answer to this, too.

John

I suspect that pushing the blade front to back is on a RAS akin to standing behind your table saw and pushing the wood toward the front. Lousy cut among other problems. Don't do it!! If you insist please have a surgeon on retainer! :)

[Bruce Wrenn]

I would like to hear the answer to this, too.

JohnSimple, cutting action of blade will lift stock off table. That's the reason when using RAS to do rips, you put front edge of blade guard down against stock being ripped.

[Alan Schwabacher]

It is true that pushing the RAS to cut will cut with the teeth rising, creating some tendency to lift the stock. If the stock shifts, the minuscule lift force can become significant. The teeth exit without backing, so can tear out there as well, particularly if not sufficiently sharp. In contrast, a pull cut directs the force down and toward the fence, in general providing cleaner cuts.

But the major problem in my view with pushing the blade through the stock is that you must postion the stock while the blade is pulled out from the saw, exposed and probably spinning, while your hand goes behind, pushing stock toward the blade. Contrast this to positioning the stock while the blade is behind the fence and out of the way, as is done for a normal pull cut. I think the pull cut setup is much safer. The advantage of a SCMS for push cutting is in the setup for the cut, which can be done with a guarded blade out of the way. Even if you plan now to set up each RAS cut with the blade pulled out but stopped, it will be so inefficient you will be very tempted to do it with the blade running.

Yes, the normal cut is a climb cut, and we are warned in general to not climb cut because the tool can self-feed and possibly get out of control by cutting too fast. But it's not hard to ensure the RAS blade moves slowly through the stock, and to ensure that your stance prevents any close blade approach even if it does feed too fast. It's possible to lose control of feed speed, but the path of the blade will remain predictable.

If you want to use the RAS with a stacked dado set for tenon cutting but are concerned about control, try taking the cut very slowly, perhaps pulling the saw into the stock only a little bit before pushing it back. Make sure that you can take small bites, as overfeeding would cause larger than intended bites, but in this mode not much larger. If you have difficulty keeping the bites as small as you'd like, you could regain that control by reducing the depth of cut.