Unisaw FAQ

 

Below are some of the questions that I have received over and over, and spend a large part of my day answering. I will be adding to this list as time goes on. If you do not see a topic you would like covered, please email me from the technical help link from the home page.

A short history…

The Delta Unisaw first appeared around 1939 or so. The idea was to have everything needed combined into one cabinet, hence the name uni-saw. Up until then, large saws were driven by large pulleys and flat belts, like the kind of old equipment you still see in some old factories and mills.

Even though over the years this saw evolved into what we have today, very little has changed in the basic saw design. Indeed most parts on today’s saw will fit and work on the original 1939 model!

Most of the changes came in the area of the motor and electrical packages. Motors have continued to become more powerful and smaller in size, and the controls safer and more user-friendly. The Delta Unisaw is now the most popular and coveted tool in the shop.

Q. Can I use a  5 hp  Unisaw in my home workshop?

A. Probably, however you should check your wiring and main panel carefully. Due to the heavy current draw of this saw, you will probably have to install a new, larger breaker into the main panel. This also means heavier wiring to the saw ( probably number 10). You should consult with an electrical contractor and your local building codes first.

  My question to those who want the extra power is " Do you really need the 5 horsepower motor?" For most applications, especially in the home shop, the three horsepower motor supplies plenty of power. If you are a heavy industrial user ripping large beams, then maybe the five horsepower motor is what you need. But then, you would probably choose a three phase model.

Q.     Should I buy a right tilt or a left tilt?

A.        This is strictly up to you. Delta introduced the left tilt to be in a position to compete with Jet and Powermatic. The right tilt is still more popular with Unisaw users. The small disadvantage of having the blade tilt into the fence is offset by the safety of having it tilt away from the miter gage, since most users run the miter gage on the left side of the blade. Again, this may differ if you are left handed, ( or right brained). The new re-designed Unisaw is only available in left tilt.

Q. Speaking of Jet and Powermatic, why shouldn’t I buy one of those instead?

A. Jet and Powermatic both make very fine saws. The reason I recommend the Delta is simple. If you need a part for your 1940 Unisaw, it is most likely still in stock, and indeed, its the same part that fits the new 2008 Unisaws. Since the design has changed very little, there is a huge body of saws out there, all the same. Imagine if it were the same with cars! Also, Delta has a service network and factory support network that is second to none. Speaking from an independent distributor’s point of view, I see them constantly trying to improve their product.

Q. Should I buy a Unifence or a Biesmeyer fence system?

A. They are both very good fence systems, the choice is up to you. I tell buyers to go to their local distributor and play with both of them before deciding. The Biesmeyer takes less time and sets up easier than the Unifence. The Biesmeyer seems to be more popular with our buyers. Note: The new redesigned Unisaw comes only with the Biesemeyer Fence /

Q. What should I look for when buying a used saw?

A. I get this one a lot. If you can find a used Unisaw, it can represent a good value or a money pit. If you but an old- run-out model with a three phase motor and plan to rebuild it and use it in your cellar, get out your wallet!

What you should look for is a newer saw (the last 20 years or so counts as newer for unisaws), one that has a three horsepower, single phase motor. There are also some units that were built for a time using the one and one-half and two horsepower motors. Make sure that the motors turn at 3450 RPM, not the older 1725 RPM. Check the fence and make sure it slides easily and is true. Look underneath and check for rust on the gear racks ant other moving parts. Some light rust is ok, but it should be able to be removed easily. Check the angle and elevation gear rack and worm gears for excessive wear. Look at the inside left rear trunnion support ( a weak spot) to check for breakage. Check the table for rust or pits. Light rust is OK, it can be removed. The alignment of the blade to the table is not important if it is off a little, it can easily be adjusted. Make sure it cranks up and down and tilts easily. Be sure all the accessories ( motor cover, dust door, extension wings etc) are with it, as they can be expensive to replace. Make sure the proper electrical controls are there and working. They can also be expensive to replace or repair. Run the machine ( without a blade!) and listen for any excessive vibration. If found, loosen or remove the drive belts to localize the noise. If it is still noisy after removing the belts, the motor probably needs to be rebuild. If not then it’s the arbor assembly or the belts causing the noise, and will have to be replaced or rebuilt. If you still want the saw, use these points to bargain with.

Q. I bought a saw with a three phase motor and I want to use it in my cellar. What do I need?

A. Get out your wallet again! You need either a new motor and controls, or a phase converter. A phase converter does just what it says, it converts single phase power to three phase power. There are usually two types available, rotary phase converters and solid state or static phase converters. A rotary phase converter is simply an electric motor and a three phase generator connected by the same shaft. The motor turns the shaft and the generator produces the three phase current. They tend to be heavy and expensive. A unit capable of running a three horsepower motor will run around $600.00 or so. The advantage is that you can pull full power from your motor. A static phase converter costs less, a unit that will run a unisaw will cost  around   $200.00 or so, but they are rated to only about 2/3 of your total power, i.e. a three horsepower unisaw motor can only produce about two horsepower. For more info on phase converters, see our links page.

Q. I need a new motor on my Unisaw. What do I order?

A. It depends on what you have now. Earlier unisaws used a large, one or one and one-half horsepower motor running at 1500 to 1725 RPM. If you have this motor, and are changing it because it is fried, I would seriously consider re-winding it. Even though these motors were rated at only   one to one and one half horsepower or so, they developed a LOT of torque. The oversize, five and one half inch motor pulley overdrives the arbor to a speed of 3000 RPM or so. This is plenty of power for the home woodworking shop. I see a lot of these motors still in use in old lumber yards. If you want to change out this motor, you will need the  new 3450 RPM motor , a new motor pulley ( it’s smaller) and a new set of belts (they are shorter). Depending on the switch installed, you may have to install the new GPE style switch. The new motors are not overload protected, they rely on overload protection from the switch assembly. You MUST have overload protection installed. The older motors had resets built into the motor,or in some cases, did without, and could use simpler switches. If you decide to rewind, make sure you go to a quality shop that has rewound these motors before. With a rewind, you get all new wire, with the newer types of high temperature insulation. It should be better than new. Expect to pay $200.00 to $300.00 or so. Note: if you have one of the older cabinets with the oval cut-out, you may have to cut out the opening square to allow for the new motor. We sell only motors made by Delta. I know there are other "clones" out there, but some of them are of questionable quality. I have heard complaints from people who have bought these motors and complained  they do not run smoothly. One person who had bought an aftermarket motor had so much trouble with a rumble his motor was making, that he finally tracked down the engineer of the company, who admitted that their motor rotors  were originally balanced for 1725 rpm, but they were running them at 3450! They just welded on the special bracket, cut off the old one, substituted a 3450 rpm stator and sent them out the door. He returned it and bought the Delta motor, and has been happy since. You get what you pay for...

Q.     My saw makes a "clunk" when it starts. What could cause this?

A.       On the elevating shaft, inside the saw toward the back, there is a round stop collar with a locking set screw. First crank the blade down, and then up just a few turns, enough to tension the elevating shaft. Now check to make sure that the stop collar is seated all the way back against the rear Trunnion assembly. If it is not, loosen the set screw and tap the collar toward the back of the saw, and then re-tighten. If this collar is allowed to move forward, the whole elevating shaft will move back and forth, allowing the blade arbor to jump when the saw starts. This causes the "clunk" on start up. Another source of this noise could be a loose arbor pulley. There are two set screws in the grooves of the arbor pulley. They can be accessed from underneath the saw if you rotate the arbor until they are uncovered by the drive belts. Make sure you unplug the machine before attempting this!

For saws with low voltage controls:

Q.    When I press the start button on my Unisaw there is a surge of electricity sent to the contacts in the housing in back of the saw( I can hear them click), the blade turns a little, but not a full revolution, and the breaker disengages. After walking back to the breaker and turning the circuit on again and going back to the saw to push the start button, sometimes it will happen again, sometimes it operates properly. Do I need a new controller? Is that something that you sell?

A.    No, I think the problem is in the motor. What's happening is that there are a set of contacts inside the motor that are activated by a centrifugal switch. The contacts at rest are switched to the "start" windings in your motor, sort of like first gear in your car. When the motor starts and spins up, the centrifugal switch opens the contacts, and the current is switched to the "run" windings, like third gear. Sometimes the contacts get burned, or get contaminated with sawdust, so they fail to close when the motor stops. When this happens and you try to restart the motor,  its like starting your car in third gear. It stalls. In your case, the breaker gets hot and pops protecting the motor. The only solution is to open the motor up and clean or file the starter contacts. Not a job for a beginner. Bring it to a motor shop and explain what happens. If this happens too often, you can burn out the windings on the motor... If the blade tried to turn, then stopped when you released the start switch , then the problem could be  the controller   relay  not latching up. Disconnect the power, open up the large relay box on the back, and blow out the sawdust from between the relay contacts. Most times, this will solve the problem.

Q.  I recently purchased a 5hp. 3 phase Unisaw.  I had it set to run on 3 phase power at my old shop but found when we relocated to our new building that we don't have 3 phase power available only 220v.We only use the table saw on rare occasions less that 4 hours per month is there any way to run this saw on 220 and leave one of the leads un-hooked ? Or do I need to purchase a phase converter, I seem to recall 15 years ago I ran into
the same situation once before and there is a way to wire the motor to run on only 2 of the 3 windings.any suggestions ?

A.  Yes you can, and it will work fine, for about 5 minutes. After that it will burn up. Once you let the smoke out of a motor, its history.   What you are trying to do is something we call "dropping a phase" in industry. It happens in factories when one line of a three phase service fails. If the motor is not protected with some kind of loss of phase control,  it will burn up quickly. Use a phase converter, or convert to a single phase motor.