Replies

1. 
   PeteBradley | Jul 22, 2006 05:53pm | #1

   The cost of a motor over 1.5 HP would be a substantial chunk of the original cost of the saw. First things first. What problem are you trying to solve? If your machine is bogging down, what are the circumstances (what band, what material, what kind of cut)? What kind of circuit (and any extension cords) is feeding it?

   Pete

1. 
   PeteBradley | Jul 22, 2006 06:43pm | #3

   This kind of question comes up a fair bit on FWW. Here's a first attempt at a decision tree for solving it. Comments, additions welcome:

   Why do you want a new motor?

   1. My saw is bogging on deep cuts or green wood:

   Are you using a sharp, good quality thin-kerf band with a TPI of 3 or less (NOT the band that came with the machine)? If not, call a good band supplier like Suffolk Machinery for advice on what you need.

   Are you running a wider band than you need or your machine can easily handle? It's not uncommon for a machine to perform poorly if you run the biggest band it will take. For example some models have 3/4" capacity but may run much better at 3/8" or 1/2".

   Are you running your machine through an extension cord or on a circuit with other loads? This can reduce power and put undue load on your motor. Eliminate cords and/or go to 220V. If you have to use an extension, use one conservatively rated for the amps and length.

   Make sure the workpiece is well supported so it can't twist or tilt during the cut.

   2. My saw is bogging when I try to slice logs, especially green ones:

   Logs are challenging and green logs more so. Check out question 1 first. If your machine tends to bog partway through the cut, it may be that the log is not sufficiently supported. You need to be sure the log can't roll even a little. One way to do this is to joint one side flat and run that down the table. You may also need to insert a wedge into the kerf behind the blade to avoid it closing in on the blade.

   3. I want to cut green logs and/or pallets all day:

   Was your machine designed for heavy duty work/abuse? It may not be worth putting on a big motor, especially if your machine is an introductory or hobbyist model.

   Single-phase motors over 1 HP are not cheap, and used single phase motors over 1HP are less easy to find than most. If you have 3-phase, that's a cheaper way to go. Be cautious of HP ratings, especially on import motors. If the price looks too good to be true, the motor is likely to be overrated, inferior type(e.g. split phase), not rated for continuous duty, etc.

   If you have the room, power, and will, big old cast iron band saws are frequently available for less than $1K. However, you need a way to move them and they're usually 3-phase. Don't plan to move one down a flight of stairs.

   4. My neighbor just bought a catalog band saw with a "3 HP" motor for ripping pen blanks and he told me mine is underpowered:

   Smile, congratulate him on his purchase, and get back to woodworking.

   Pete

   Edited 7/26/2006 12:06 am ET by PeteBradley

1. 
   WillGeorge | Jul 23, 2006 10:58pm | #4

   This caught my eye.. I use a 1" wide 3 tooth per inch to resaw. A plain old LENOX blade.. That blade will cut through anything (well I never tried metal yet!) Not to good for curves though!

2. 
   mwenz | Jul 22, 2006 06:41pm | #2

   As was mentioned, it may not be cost effective for a larger, quality motor.

   But even at that, there are other issues. Frame strength is one. If you are over taxing the Jet, your blade may not be optimal. I too have a Jet 18" BS. I resaw to its capacity and in general use it hard. The motor is one of the least things I would change about that saw.

   Take care, Mike

3. 
   DaveDickey | Jul 26, 2006 06:34am | #5

   O.K...............  I'll consider other options...............  The blade is from Laguna..... a 1" with 2 TPI . I'm trying to resaw 6" dryed pine boards.

   I like the 220 idea. I  can rewire and convert to 220.  I think I'm getting enough power  via the 110 but maybe the 220 would be better.

1. 
   PeteBradley | Jul 26, 2006 06:52am | #6

   I've resawed a whole lot worse with similar horsepower. I'm assuming the machine is bogging in the cut, true? I'm also assuming that the machine is in good working order and spins freely by hand. These problems are always good for some head scratching. It will be interesting to see what the root cause is.My bets are on the band binding or insufficient power reaching the motor.A 1" band wants a lot of power just to turn it and pine isn't that friendly to resaw, but I would still expect it to work as long as you feed it slowly. Does the band run without fluttering? This is a sharp wood band, right?How are you supporting the boards? Is it possible that they are tilting and binding the band or closing in behind the band? Do the cut pieces wind up noticeably bent after the cut?220V is always a good thing.Pete

   Edited 7/25/2006 11:58 pm ET by PeteBradley

2. 
   mwenz | Jul 26, 2006 06:53am | #7

   They should have never sold you that blade for that saw. It's too much blade.

   Try a simple, inexpensive 1/2" or 3/4" Woodslicer from Highland Hardware. You'll wonder where all the power came from and the cut is better.

   Take care, Mike

1. 
   PeteBradley | Jul 26, 2006 07:00am | #8

   Just to add what Mike said, I'd be running a 3/8 or a 1/2" band at 3 TPI for this job. If your 1" band is a carbide-tipped industrial monster, that's definitely part of the problem.Pete

   Edited 7/26/2006 12:10 am ET by PeteBradley

2. 
   DaveDickey | Jul 30, 2006 06:25am | #23

   Thank you .......................  I'll try that.     Dave

3. 
   forestgirl | Jul 26, 2006 08:02pm | #9

   "I'm trying to resaw 6" dryed pine boards"  Send 'em to me and I'll do 'em on my old Grizzly made-in-Taiwan 1019Z 14" saw with a 1 HP motor and Timber Wolf blade.  Paid heed to those who say change the blade -- Timber Wolf or Woodslicer.  Make sure everything is tuned and tensioned properly.  IMHO, it has nothing to do with 110 v. 220.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

4. 
   jackplane | Jul 26, 2006 08:17pm | #10

   Another issue overlooked is that your saw may be under-tensioned, and should be near the upper limit of the torque specs when re-sawing. 

1. 
   John_D | Jul 27, 2006 04:58am | #12

   Don't know about his Lenox blade, and that may be what you're discussing, but for my 3 TPI 1/2" Timberwolf blade, the low tension (just enough to prevent flutter) they recommend works extremely well.My goal is for my work to outlast me.  Expect my joinery to get simpler as time goes by.

1. 
   ChrisK | Jul 27, 2006 05:27am | #13

     My 1HP 14" Delta was cutting fine (even resawing oak) until I made some modifications to the belt drive (changed it to a 3-speed arrangement).  I didn't realize the first time I used it after the modifications, but the belt was slipping under moderate to heavy loads, resulting in considerably reduced power and cutting speed.  If your saw is new, the belt may never have been tension properly and might be the problem.  

   Chris 

1. 
   John_D | Jul 27, 2006 07:16am | #15

   I think you've mis-addressed your useful reply, which I'm mentioning because the OP may not see it if he doesn't get a notice. :)My goal is for my work to outlast me.  Expect my joinery to get simpler as time goes by.

2. 
   forestgirl | Jul 27, 2006 06:51am | #14

   His recommendation ("...and should be near the upper limit of the torque specs when re-sawing.") seemed suspect to moi also.  Even with a Lennox blade, or any not-low-tension blade.  I've never seen any of the bandsaw gurus recommend that approach to tensioning.forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

3. 
   jackplane | Jul 27, 2006 03:55pm | #16

   You may all continue to re-saw with what feels comfortable. From experience, and from a few FWW articles, the bandsaw should be torqued high for resawing; some of the lower end 14" saws simply cannot be torqued high- they lack the frame strength.

     The smaller bandsaws also work easier when re-sawing if they use a narrower, 1/2 to 3/4 blade, instead a wider blade like 1"  is recommended for large bandsaws. TPI and tooth configuration is another issue that's important here. 

1. 
   PeteBradley | Jul 27, 2006 04:50pm | #17

   This contains a lot of rehashed conventional wisdom that isn't necessarily applicable. First, it's tension, not torque. There's no question that some extra tension helps for a tall resaw, but it's not absolutely required. Even a small machine can easily achieve the tension needed to resaw as long as you don't go nuts on blade width. I've done high-quality resaws 13" deep with a 3/8 band. Michael Fortune's excellent article in FWW #207 covers these issues in a more detail.Pete

2. 
   jackplane | Jul 27, 2006 05:23pm | #18

   "rehashed conventional wisdom"

   And your advice is innovative and new? We can argue semantics, and yes the right term is tension, not torque, but either way one ends up in the same place.

   Lesser tension does help on smaller saws. Obviously, the narrower the blade, the less tension required. My object here is to help the original poster by exploring all issues that may help him with his bandsaw, not write a definitive treatise for general critique. 

3. 
   forestgirl | Jul 28, 2006 01:41am | #19

   Problem is, the advice was so vague and mispoken as to be virtually useless. 

   I'll rely on Mr. Lonnie Bird to refute some of your offerings, referring to The Bandsaw Book sitting on my bookshelf.  Lonnie's quotes in italics.

   "Obviously, the narrower the blade, the less tension required."  All blades, regardless of width, require the same amount of tension for maximum beam strength.  The variable factor is the amount of pulling force needed. (page 93)

   "Another issue overlooked is that your saw may be under-tensioned, and should be near the upper limit of the torque specs when re-sawing."  Don't fully compress the spring....  You might get more tension, but the spring is there to absorb minor vibration or slight bounces during cutting.  The spring helps prevent the blade from breaking. (page 96)  AND You only need maximum tension for the most demanding cuts, such as sawing dense hardwoods or stock of the maximum thickness that will fit under a saw's guides.  (page 93)        Since, according to posts #6 & #1, he's trying to resaw 6" pine boards on an 18" Jet saw with a 1.5HP motor, I think we can assume he's not anywhere close to something "demanding" on that saw.

   The biggest problem I see with this entire thread is that we never did get any specific information from the OP about what "symptoms" led him to believe he needs a bigger motor on his saw (not!).  Bogging?  (assumed by some).  Barrelled cuts??   Wandering??  Although some of the recommendations may cure the problem, it's hard to say since there's no description of it.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

   Edited 7/27/2006 7:44 pm by forestgirl

4. 
   yieldmap | Jul 29, 2006 08:24am | #20

   I'm surprised that a 18" saw with a 1.5hp is wired for 110 anyway...does this seem odd?  I would've thought all 18" saws were wired for 220 out of the box.

   Did this saw have a plug out of the box, or did you put one on it?

   If the motor is set up for 220, and you've been running it on 110, then it may be ruined by now.  If you're not sure, then have an electrician or electrically-suave buddy look at the motor setup.

5. 
   forestgirl | Jul 29, 2006 04:37pm | #21

   This wasn't my saw (or my OP [original post])  Whethr a motor comes pre-wired for 110 or 220 depends partly on the HP/amp draw of the motor.  Most 1.5HP motors seem to be optional 110/220V.  At least the Jet's are, so not at all unusual. 

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

   Edited 7/29/2006 1:01 pm by forestgirl

6. 
   mwenz | Jul 29, 2006 05:32pm | #22

   The Jet comes pre-wired for 110.

   The saw is fine. The guy needs a different blade. It's pretty simple.

   Take care, Mike

5. 
   TKanzler | Jul 26, 2006 08:41pm | #11

   I like the 220 idea. I  can rewire and convert to 220.  I think I'm getting enough power  via the 110 but maybe the 220 would be better.

   It's isn't so much an issue of 'getting enough power' through the electric system, as it's capable of passing thousands of amperes for short duration.  It's (possibley) an issue of low voltage.  The torque a motor can produce depends on the voltage, not the amperage, and when the voltage sags, the torque curve also sags. 

   A typical continuous-duty induction motor is rated to output a certain hp indefinitely, which translates to torque x speed.  A 1.5 hp motor running at 1725 rpm is outputting 4.57 lb-ft of torque, but that same motor is capable of outputting much more torque than that (anywhere from 1.5 to 2.5 times that for a single-phase motor), albeit for a short time.  How much more depends on it's design (published breakdown torque), but that figure is valid only when the motor gets it's rated voltage (usually 115V for US made motors).  Since the only way you can tell how much power the saw has is to run it until it loses steam, so to speak, you're almost certainly running it much harder than it's 1.5 hp rating - you're testing the limits of it's performance envelope.

   As the supply voltage is reduced below the motor's rated voltage (on the nameplate), the torque curve droops as the square of the voltage ratio, so a small voltage reduction can potentially have a large effect on the maximum torque the motor can produce.  This is the root cause of tools like contractor saws and air compressors getting wimpy when run on long extension cords.  That's also why folks often report a large apparant increase in 'power' when switching over to 240V - half the current at twice the voltage results in 1/4 the percent voltage drop in the wiring for a given load, so the motor is running at closer to it's design conditions, with a subsequent improvement in maximum torque, and hence "max developed hp".

   For a quick test, if the saw is plugged into a duplex outlet, measure the voltage at the receptacle while pushing the saw to it's limit.  Have someone else read the meter, of course.  If the voltage drops to no more than a couple of volts below the motor's nameplate voltage, there is not much to be gained by switching to 240V, but if it drops quite a bit, like down to 100V, that's (100/115)^2, which is about 75%.  The torque curve has dropped to about 75% of what it would be at full voltage, assuming the motor nameplate says 115V.  240V is a good candidate here. 

   Of course, as posted above, the right blade and proper technique can have a huge effect.  I would explore that, and all other mechanical options first, and consider the voltage at the tool second.  Pushing the motor to where the voltage drop begins to matter means you're pushing it very hard, so anything you can do to make the load easier in the first place is a good thing.Be seeing you...