# Table saw/ RAS saw RPM speeds



## BBC3 (Aug 31, 2012)

So I am noticing that the typical speed of the better table saws is more like 3450 as compared to 5000 rpm on the cheaper table saws I am accustomed to (so better being relative compared to trash).. I am not sure what speed real professional saws operate at, but I suspect they are probably even variable.? So what is the difference.

One of my concerns is the "Chomp effect" I call it that I have experienced with my RAS saw recently. It really scared me off using it at all. Its one thing to have the saw lock up or bind on a sheet good being ripped, but its another to have a slim peice of hardwood going in the ripper and have it explode in your face!! I suspect this is also related to blade speed? I have pulled some pretty goofy cuts off on some thin pieces of hardwood with my $100 5000rpm POS and never really had a bite, lock, or bind/jerk type scenario occur. Perhaps I am just holding the wood better because I get a better downward angle on it and not related to speed at all? Could anyone advise..

FYI - I noted in another thread where I was suspect of the RAS binding on wood due to the loose bearings, but when you tighten down the screw lock on the carrage radial arm - it kinda takes some of that out of play? But I dont recall in my head whether the lock screw was pulling from the set bearing side or the adjustable (loose) side - which would make a difference of course. So basically I am still trying to figure out why the saw was binding so that I can must the confidence again to use it LOL..


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## Dave Paine (May 30, 2012)

There is motor speed and blade speed.

The typical RAS, like my old Craftsman, was direct drive, so the motor had to rotate at the same speed as the blade. Likely around 3400 rpm, but I do not recall.

A contractor style or cabinet style table saw has the motor driving a pulley which drives a different size pulley for the blade.

The motors are likely to spin at around 1760 rpm. The blade speed may be around 3400 - 3600 rpm.

I happen to have the new Delta Uni-saw and for some reason Delta increased the blade speed to be 4300. Perhaps due to using a drive belt, so can use a smaller diameter pulley on the blade.

A table saw can catch a piece of cut off wood just as easily as your RAS experience. The result can be equally scary, sometimes worse, since my table saw has a 3HP motor - almost twice the power of the old RAS.

I am a big fan of zero clearance inserts on my table saw. The only time I do not use one is for dado's.

Before I switched my first table saw to having a zero clearance insert, I also experienced a piece of the offcut dropping between the blade and the insert. In this case it broke up, but went into the cabinet. I was lucky. I had other instances when the piece just got a small cut taken out.

With the RAS, I can see it nay be difficult to prevent an offcut from being caught by the blade.


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## FrankC (Aug 24, 2012)

With any cutting tool the important number is feet per minute that the outer edge of the teeth are travelling at. A saw with a small diameter blade will have to run at at higher RPM than a saw with a large diameter blade to achieve this speed.

These speeds are determined under no load conditions, a saw with a motor of adequate power will not bog down making normal cuts, however an underpowered saw will loose RPM's under load so to compensate many of the cheaper saws run at a higher RPM to maintain the required feet per minute speed under load.


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## cabinetman (Jul 5, 2007)

The motors for both the TS and the RAS will have the RPM's listed. Many are 3450 RPM. But, I don't think that is your problem with the RAS. It's more likely that you have the wrong blade installed. RAS's work best with a negative hook carbide tipped blade. The tooth design should be for the type of cuts you are doing...mainly crosscuts.

I would not suggest ripping with a RAS. If you replace the blade with a proper one, and experiment with the technique of a graduated pull into the stock, you won't get the "grabbing" or "chomping". You are more than likely pulling the blade into the stock too fast. The negative hooked blade is less of an aggressive cut.









 







.


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## FrankC (Aug 24, 2012)

As the Cabinetman says the proper blade and technique is very important on a radial arm saw.

I saw a demonstration at a tool show by a blade rep where he pulled the saw half way into a piece of 3/4" plywood and let go of the handle, the spinning blade just sat there not moving. Not something I would try at home.

I worked for years using a radial arm saw as my primary saw and was happy to do so because I did not enjoy using the table saw I had with a tilting table.


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## cabinetman (Jul 5, 2007)

FrankC said:


> I saw a demonstration at a tool show by a blade rep where he pulled the saw half way into a piece of 3/4" plywood and let go of the handle, the spinning blade just sat there not moving. Not something I would try at home.


I think he pulled a card trick on you. If the saw was pulled and stopped, it should just sit there and spin. It's likely he might have bumped it back a hair.:laughing:



FrankC said:


> I worked for years using a radial arm saw as my primary saw and was happy to do so because I did not enjoy using the table saw I had with a tilting table.


It's likely that many use equipment to get the job done. Some are more careful than others. Like this guy in the picture below. I don't know if that qualifies as "innovative" or not, but sure looks like an accident waiting to happen.:yes:
.


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## woodnthings (Jan 24, 2009)

*Your cheap table saw's RPM at 5000*

That's because it's not much more than a hand circular saw inverted in a table using a universal motor at 5000 RPM. The Table saw has a separate belt driven motor and arbor where the speed can be increased by changing pulleys sizes. A typical arbor speed on a 10" table saw is around 3800 RPM, or so slighlty higher than the motor's shaft speed of 3450 RPM.
http://www.grizzly.com/products/10-Hybrid-Table-Saw-with-Riving-Knife-Polar-Bear-Series-/G0715P

A larger blade will normally be slower or lower in RPM since the peripheral tip speed increases with diameter. Motors are typically 1725 or 3450 RPMs so the speed is changed by changing the pulleys. 
Info:
http://home.howstuffworks.com/question338.htm

The early Craftsman line of RAS and driect drive table saws used virtually the same motor.


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## BBC3 (Aug 31, 2012)

You bring up a great point. I have only recently noted that the better table saws are pully operated by the point of the energy at the blade. And I was comparing 10" to 10". AND its funny how the marketing of various products will choose to either discuss amperage or HP, and some involve RPM or not in their disussion. Many times an illlusive use of statistics to lie to the layman... And I am not sure how HP and AMPERAGE relate apple to apple, but I suspect that amperage my hint toward torque, which may too. But I am not engineeringly astute enough to go there..

But the difference is still negligeable, and I am still wondering why the cheaper table saws elect 5000rpms at the blade, and I still suspect that 3450 is that stock choice of the higher quality saws whether table or RAS..??? There is a notable difference in the end action at the point ofcut with the 5000rpm equipment. I suspect its more of the torque vs RPM deal and also the 5000 rpm saws seem to just "chip" into things and kick em off, rather than bite and knaw - whether a mistake occurring or intended by end user action...?



Dave Paine said:


> There is motor speed and blade speed.
> 
> The typical RAS, like my old Craftsman, was direct drive, so the motor had to rotate at the same speed as the blade. Likely around 3400 rpm, but I do not recall.
> 
> ...


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## BBC3 (Aug 31, 2012)

OK - so you are saying that whenever "RPM" is discussed in advertising media, its most likely regarding the speed of the motor shaft?? So then the preferred stock speed of 10" saws is about 4K you think?

I would speculate that lower speed motors are on the higher quality saws with stronger motors, as it would be more efficient to have the larger pulley on the blade and I would suspect, thus giving more options for slow speed cutting with strength too...?




woodnthings said:


> That's because it's not much more than a hand circular saw inverted in a table using a universal motor at 5000 RPM. The Table saw has a separate belt driven motor and arbor where the speed can be increased by changing pulleys sizes. A typical arbor speed on a 10" table saw is around 3800 RPM, or so slighlty higher than the motor's shaft speed of 3450 RPM.
> http://www.grizzly.com/products/10-Hybrid-Table-Saw-with-Riving-Knife-Polar-Bear-Series-/G0715P
> 
> A larger blade will normally be slower or lower in RPM since the peripheral tip speed increases with diameter. Motors are typically 1725 or 3450 RPMs so the speed is changed by changing the pulleys.
> ...


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## BBC3 (Aug 31, 2012)

Im pretty sure the blade I used has a large part to do with the degree of binding I had. And even when trying to control a sheet good with people on both ends, it just seemed to be an operation with no "feel", which I suspect has to do with the hooked blade I have. It begs a great point on how far up one has a table saw blade when working with media, and how that effects??? Which is an option you dont have with RAS unless one chooses to slice a big cut inthe table for certain operations on the RAS??



FrankC said:


> As the Cabinetman says the proper blade and technique is very important on a radial arm saw.
> 
> I saw a demonstration at a tool show by a blade rep where he pulled the saw half way into a piece of 3/4" plywood and let go of the handle, the spinning blade just sat there not moving. Not something I would try at home.
> 
> I worked for years using a radial arm saw as my primary saw and was happy to do so because I did not enjoy using the table saw I had with a tilting table.


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