Shopsmith Forums

Is the motor in the model 520 more powerful than in the model 510?
Since I'm not well versed in electric motors, what is important in an electric motor, the horsepower it generates, the volts or the amps?

Is this also one of the important differences in the model 520 vs the 510?

Bob
San Diego

Nope! The 510 and 520 use the same headstock. Motor and all. There may have been some small changes like the plastic protector over the axillary shafts.

rdewinter wrote:

Since I'm not well versed in electric motors, what is important in an electric motor, the horsepower it generates, the volts or the amps?

Bob
San Diego

The Horsepower! The Volts and Amps merely come along for the ride. The Voltage is only important to the extent that you must have a matching source(115V or 230V). The amperage is an indicator of efficiency, but more importantly you must have a source(outlet...) capable of supplying it.(15A minimum, 20A recommended)[115V...halve as much for 230V]

The SS is available in dual voltage models(115V/230V) but most are 115V. In order to use a 230V model a special 230v circuit(outlet) must be available/provided.

For use in the US, 60Hz is used. Some other countries use 50Hz.

Actually volts and amps do play a role. Horsepower is defined at 745.69982 watts. Watts are found by multiplying volts times amps. So at 110 volts 6.779 amps equals 745.69982 watts or 1 hp. 13.55817855 amps equals 2 hp.

Those are perfect world numbers with motors of hundred percent efficiency.

Real world 8-8.5 amps equals 1 aprox. horsepower and 16 -17 amps equals approx 2 hp. Since most tools carry a UL approval sticker and to get the UL sticker a 110 volt motor must be able to run on 15 amps or less. So it is virtually impossible to have a UL approved motor that is rated much more than 1 1/2 to 1 3/4 horse power.

The compressor manufactures once rated their 110 compressors at all sorts of horse power and Porter Cable for one got sued and the result of the class action suit was. If you owned a PC compressor model # XXXXX manufactured before XXXX you could get various tools for free. I think I got a 50 foot hose and some snap on connectors.

Since then manufactures have been real careful tossing around their horse power numbers. Some like Delta/Porter Cable use precise numbers. Others still list wild numbers but have various disclaimers such as "developed" horsepower, "realized" horse power and etc. These claims usually mean the produced horsepower of the motor right before it self destructs or nothing meaningful.

Some of the foreign manufactures list interesting horsepower numbers but if you research them they use a far different horsepower measuring system and often when questioned they explain they are using 50HZ or different line voltages.

Basically to have anything higher than 1 1/2 horse power you need 220. But that doesn't always mean you get more horse power. If you look at Shopsmith's 220 machine it is rated at approx 1/2 amperage of the 110 machine which means it produces exactly the same horsepower.

A/C induction motors are rated a certain HP at a maximum continuous temperature rise. This is done in a dynometer lab with thermocouples in a lot of places on the motor. This does not result in haphazard ratings from one manufacturer to the next, because the HP, frame size, and temperature rise (55 degrees C) of induction motors is standardized by the National Electrical Manufacturer's Assocation (NEMA). One of the characteristics of single phase and three phase induction motors is that the speed torque curve is very flat. Thus the motor can be overloaded, almost to the point of breakdown, without very much drop in speed. Thus a 1 HP motor can withstand brief overloads of say 1 1/3 HP, but of course would eventually burn up with this overload in continuous operation. Perhaps this is where the "developed HP" term comes from, but this term is not used by NEMA. Some motors, built with higher temperature insulation are rated 1.15 service factor, and this would be so indicated on the nameplate. Induction motors are wound around a certain even number of poles, which gives the motor a set speed at 60HZ, ie: 3600 rpm - 2 pole, 1800 rpm - 4 pole, 900 rpm - 6 pole, ect. The actual full load speed will slightly less due to slippage between the field and the rotor, thus nameplate full load speeds are usually around 3450 rpm - 2 pole, 1750 rpm - 4 pole, 870 rpm - 6 pole.

A great many universal type electrical motors and now being used to power stationary power tools. This of course is a cheaper power source than a NEMA induction motor. Universal motoprs can be made to operate on A/C or direct current. They have brushes and commutators and operate at very high speeds, 10,000 to 20,000 rpm being very common. There are no standards, NEMA or otherwise for universal motors. They are electrically less efficient than induction motors and characteristically they have a much higher noise level. They also have a much shorter life span. Since HP is basically a formula involving speed and torque, universal motors get their HP essentially from speed rather than torque. Quite often now-a-days, universal motors are rated in amps, a rating whose only useful purpose is to help you assertain if your circuit is adequate. for the user, the actual HP would be largely a guess

A/C induction motors are rated a certain HP at a maximum continuous temperature rise. This is done in a dynomometer lab with thermocouples in a lot of places on the motor. This does not result in haphazard ratings from one manufacturer to the next, because the HP, frame size, and temperature rise (55 degrees C) of induction motors is standardized by the National Electrical Manufacturer's Association (NEMA). One of the characteristics of single phase and three phase induction motors is that the speed torque curve is very flat. Thus the motor can be overloaded, almost to the point of breakdown, without very much drop in speed. Thus a 1 HP motor can withstand brief overloads of say 1 1/3 HP, but of course would eventually burn up with this overload in continuous operation. Perhaps this is where the "developed HP" term comes from, but this term is not used by NEMA. Some motors, built with higher temperature insulation are rated 1.15 service factor, and this would be so indicated on the nameplate. Induction motors are wound around a certain even number of poles, which gives the motor a set speed at 60HZ, ie: 3600 rpm - 2 pole, 1800 rpm - 4 pole, 900 rpm - 6 pole, ect. The actual full load speed will slightly less due to slippage between the field and the rotor, thus nameplate full load speeds are usually around 3450 rpm - 2 pole, 1750 rpm - 4 pole, 870 rpm - 6 pole.

A great many universal type electrical motors and now being used to power stationary power tools. This of course is a cheaper power source than a NEMA induction motor. Universal motors can be made to operate on A/C or direct current. They have brushes and commutators and operate at very high speeds, 10,000 to 20,000 rpm being very common. There are no standards, NEMA or otherwise for universal motors. They are electrically less efficient than induction motors and characteristically they have a much higher noise level. They also have a much shorter life span. Since HP is basically a formula involving speed and torque, universal motors get their HP essentially from speed rather than torque. Quite often now-a-days, universal motors are rated in amps, a rating whose only useful purpose is to help you ascertain if your circuit is adequate. For the user, the actual HP would be largely a guess

I'll have to apologize to the original poster, Bob, for not really addressing his core question; The motors in the 510 and 520 are the same.

Actually, what is most important in an electric motor is torque. A saw blade can be spun at any speed, but if the torque at the cutting tooth is inadequate, it will not tear through the wood. Most Shopsmith motors are 115V. The optional 230V motor is exactly the same HP, but only takes 1/2 the amps of the 115V motor.

The Shopsmith, with it's variable speed headstock, can do some rather heavy duty cutting by lowering the speed, and therefore increasing the torque. The feed rate has to be porpotionally reduced, but this is hardly noticeable. I have ripped a 2"x10" by ten feet rain soaked pressure treated board by reducing the speed down to around 1800 rpm.

Thanks 8iowa for the technical information. It's obvious you know electric motors, but you really went to the core of my concern with your 8x10 pressure treated rip example. I sometimes get the blade stalled when ripping larger dimension lumber, say a 4x4. You indicated that you slow down the rpm and the feed rate. On large lumber I slow down my feed rate but I always use speed R for sawing. You intimate slowing down the rpm, but what do you use as a rule of thumb to determine the slower rpm? Is it as simple as the bigger the lumber the slower the rpm? It never occurred to me to slow down the spinning saw blade. Apparently, faster isn't better (when cutting lumber!)

Bob
San Diego

Bob- I'll bet you get some burning of sawn edges when using speed R. I've found that on my machine speed O is the best for both ripping and crosscutting. Your machine may not be exactly the same as mine because of belt and adjustments.

At this speed I think it is important to use a rip blade (fewer teeth) for ripping and a crosscut blade (a whole bunch of teeth) for cross cutting.

Using this speed, I've only had burns on a rip when the board gets hung up a bit and slows or stops during cutting. Don't ever have a burn on cross cuts.

rdewinter wrote: I sometimes get the blade stalled when ripping larger dimension lumber, say a 4x4.

Bob
San Diego

Are you attempting to rip 4x4 in ONE pass? Try two passes if you are stalling.