Replies

1. 
   JohnWW | Oct 27, 2006 05:03pm | #1

   Doug,

   You can use an open frame motor as long as you understand that if it gets plugged up with dust it can overheat and get damaged or that the internal starter switch might get jammed by dust, again risking motor damage.  If the motor isn't exposed to a lot of dust and/or you are conscientious about blowing it out regularly, you can at least partially reduce the chance of dust related problems.

   3 horsepower is a lot for an 18" saw.  With the proper type of blade for the job, sharp of course, you should be able to do almost anything with 1 1/2 to 2 HP.

   Also, motor sizes are standardized.  The motor you are taking off should have a frame number on its spec plate, a two or three digit number with possibly a single letter tacked on the end.  If you get a replacement motor with the same frame number it will be the same size as the old motor, even if it is a different horsepower, and you won't have to modify the motor mount or buy new pulleys with a different bore diameter.

   If you do install a 3 HP motor you will probably have to change the machine's switch to handle the larger current draw and you will need a larger than average electrical circuit to supply the power, especially if you intend to run a 3 HP motor on 115 volts. 

   If the current switch is a magnetic type, it will need to be adjusted to match the motor size which may require replacing a part called a "heater" in the switch.  Some switches don't use heaters and can be adjusted by turning a small control knob inside the switch housing.  The heater, if it is used, is sized to match the current draw of the motor and is needed to protect the motor from damage if it is overloaded.  It is possible that the magnetic switch currently on the saw won't have the capacity to handle a 3 horsepower motor, in which case you will have to replace the entire switch.

   If your saw now has only a simple on/off switch, which is considered adequate for a 1 1/2 HP motor, you will have to install a new magnetic switch to protect the larger motor which isn't likely to be available with built in thermal protection, which is typically only available in motors of 2 HP and under.

   If you do get a motor with built in thermal protection, make sure it is the manual type, not automatic.  A motor with automatic protection will restart the motor without warning once the motor has cooled off, possibly causing a nasty accident if the power switch was left on.  On a motor with manual thermal protection you will have to reset the switch on the motor before it can be restarted avoiding an unexpected start up.

   This is probably more complicated than you thought it would be, but if you don't take the switch type and capacity into account you will risk damaging the motor or getting injured.

   John White 

1. 
   DougFraser | Oct 29, 2006 01:08am | #2

   John:Thanks for the detailed response.The reason for the motor size increase is that with a sharp carbide tipped 1" blade the saw often binds and stops with the existing 1.5 HP motor when resawing green wood. I have a friend with a 3HP Laguna and he does not have the same problems I do.My intent is to power the 3 HP motor from 230V. I have several 230V 20 Amp outlets in my shop. The saw currently does not have a magnetic switch and I plan to install one and re wire the saw internally using 12 gauge wire. I also understand about the internal setting in the magnetic switch.After reading your response, I will most likely spring for the TEFC (it is about $200 more). It sounds like the issue is increased long term reliability.Once again, thanks for the response.Doug

   Edited 10/28/2006 7:10 pm ET by DougFraser

1. 
   JohnWW | Oct 30, 2006 04:17pm | #3

   Unless your carbide tipped blade was designed specifically for cutting green wood, it is probably the source of your problem.  A blade for cutting green wood needs an entirely different geometry than a blade for cutting dry wood. 

   A blade for cutting dry wood doesn't have the tooth set and gullet depth for dealing with the large fluffy fibers created by sawing green wood and the blade will jam in the cut as you have experienced. 

   You should call Suffolk Machinery, 800-234-7297 and talk to one of their techs.  They can send you a blade made for sawing green wood that will probably allow to use the motor you now have.

   John W.

   Edited 10/30/2006 11:24 am ET by JohnWW

   Edited 10/30/2006 1:13 pm ET by JohnWW

1. 
   DougFraser | Nov 01, 2006 01:42am | #4

   John:I'll give the guys at Suffolk a call. Thanks
   Doug

1. 
   JohnWW | Nov 01, 2006 07:55pm | #5

   Something you said in an earlier post didn't sound right. 

   A TEFC motor shouldn't cost $200 more than the equivalent ODP motor, a few dollars more maybe, but certainly not hundreds.  I just looked up two very similar 3 HP motors in my Grainger catalog and the TEFC version cost just eight dollars more than the ODP.  Are you sure you weren't looking at an explosion proof motor?

   John W. 

2. 
   DougFraser | Sep 25, 2007 02:18am | #6

   John:It's almost been a year since you advised me on a motor upgrade for my Jet 18" band saw.I finally got a motor - 4.5 HP Baldor TEFC. I had a mounting plate designed and milled so it mounts just like the old motor it replaced. The problem is the new motor spins at 3450 RPM vs 1725 for the original.The Suffolk Machine and Old Woodworking Machine site recommends that an 18" band saw should run at 4000 sfpm (surface feet per minute). The Old Woodworking Machines site has a convenient sfpm calculator.http://www.owwm.com/Math/SFPM.aspSo I did the calculations to have the saw run at 4000 sfpm. This required a new drive sheave (as the new motor has a 1 1/4" shaft) and a new sheave on the band saw lower wheel. Unfortunately the JET has a 22 mm shaft for the lower wheel. I could not find a metric pulley so I purchased a 3/4" pulley (of the correct diameter for 4000 sfpm) and had it machined to 22 mm. I also had the hub machined so that it was the same thickness as the original sheave. This ensures that the upper and lower band saw wheels are coplaner.So far so go. I wired in a magnetic switch (sized to correct amperage), checked every thing multiple times and turned it on. Magical - the motor started, the blade turned and the saw vibrated like crazy. What the....? By this time the Ittura Designs catalog arrives. In the catalog Lou Ittura has a good write up about supercharging a band saw. Basically it says resaw performance is increased at higher blade speeds (up to 4000 sfpm) however one might get burning caused by the blade when cutting tight corners. The other issue identified is that the band saw tires sometimes separate from the wheels at high sfpm. Well sure enough, the tires on the wheels are separating and causing the vibration. So after investigating possible solutions 1) slow down the sfpm, 2) use urethane tires or 3) glue on the existing tires, I am going to try gluing on the existing tires. I have purchased some 3M glue designed for gluing rubber (I hope my tires are rubber and not some other rubber like material). If that doesn't work then I am going to purchase two urethane tires. I found a source that will manufacture them 20% shorter and cut them to the correct width (with the JET wheels the tire seats between two ridges on the perimeter of the wheel. The distance is 1 3/8" but most urethane tires are 1.5" wide.) The good news is that apart from the vibration the saw cuts like a dream. I can now cut very thin pieces while resawing.I probably would have been better off selling the saw and taking the money I spent on the upgrade to purchase a new machine. Live and learn!Thanks for you help!Regards,
   Doug

   Edited 9/24/2007 7:31 pm ET by DougFraser

3. 
   DougFraser | Sep 27, 2007 10:13pm | #7

   John:Quick update:I glued on the flapping band saw tires using Scotch Grip 847. Let them dry for 24 hours. Reassembled every thing last night and started the saw up.The tires stayed attached, vibration was reduce significantly. All is good. Regards,
   Doug

   Edited 9/27/2007 3:16 pm ET by DougFraser