Bandsaw replacement motor help..

[Michael Menzli]

Greetings Creekers,

I purchased a new 3 hp motor for my Harbor Freight bandsaw yesterday. I wanted to go with the 2hp however the shaft is a 1/4" larger for some reason :confused: I realize this is beyond overkill and will likely strain the system. I wanted to give it a shot for curiosity sake.

Anyways in my excitement I overlooked a really important fact.. this motor is set at 240v only. Ive researched a bit and will be using a 30 amp double pole breaker and 10 gauge wire.

Now the confusion.

Per the instructions it lists wires as p1 t1 l1 etc. Is L1 considered black and the L2 white from my main circuit or vice versa? I want to run this ccw.

Secondly. I would like to continue to use a switch to power on and off. Can I use the original switch mounted on the saw. Can I basically cut the plug and wire in one designed for the 240 circuit or will this become overloaded? If I cant use it what would be recommended. I only have big box stores to gather materials.

Thanks in advance
Michael

[Salem Ganzhorn]

Michael, I am not an electrician and if you electrocute yourself it is not on me :).

But most 3hp motors are fine on a 20a circuit. Check the motor label for amperage.

Most inexpensive tool switches are 110v only but check the label on the switch it will tell you. Grizzly sells good switches for cheap.

As for motor direction it has nothing to do with how you wire it to the wall (for single phase). The two hot leads on a 220v circuit are interchangable. Check the motor label for direction. Some motors only turn one way. Others are reversible and the label will tell you how to wire it. Switching direction is done by reconfiguring how the internal leads are connected.
Good luck!
Salem

[Michael Menzli]

Thanks Salem..thats exactly what i needed. I dont get why things cant be explained in simple terms. Ive got it wired up for ccw per the instructions

Now...as far as switches. I purchased a 30 amp double pole single throw light switch rated for 277volts. Im confused as to how this works on a 240 volt circuit. Ive wired the 240 as 2 hots and 1 ground with no neutral. Can this switch be used to power the saw on and off? I have installed a 20 amp circuit breaker box as well but want that for safety and not to turn my machine on and off

[Jack Wilson]

Michael, the amperage is what you need to consider, not the voltage. 3 hp @ 220-240V ought to run around 15 amps or so, that can be carried on 12-2 with ground, and a 20 amp double pole breaker. The black AND the white wires will BOTH be hot, one on each terminal of the breaker, ground goes to grounding bar. The switch? Sounds like its rated for 3 phase @ 277. I am not too sure about that.

[Salem Ganzhorn]

I think both amperage and voltage is important for the switch. You should not exceed either of the specifications. And I agree with Jack that 277 screams 3 phase. Could you use this to disconnect a 1 phase circuit? Probably but I have no idea how :). You can buy a 220v 20a switch pretty cheap from HD/Lowes. I am not sure if this is kosher or not but I use the breaker as the disconnect. I have 4 small children and I shut it all down from the panel when I close up shop.

As for wiring you probably want a 220v 20a breaker, 12 gauge wire and an approved 220v 20A receptacle. You probably should also get it inspected. It will cost 40-50$ but you will know it is up to code. The inspectors in my area are quite nice and take the time to help a home owner (note they are NOT nice to electricians :)).

Good luck!
Salem

[Michael W. Clark]

Good information above. I bought a 220V 2-pole, single throw switch for my air compressor from HD for about $15 IRC. I don't know what your switch looks like on your saw, but my Delts BS has a pushbutton switch that looks like those sold at Grizzly and Rockler. You can buy 220V versions of these that may fit your saw.
Mike

[Peter Kelly]

Return the 277v switch. It is a 3-way switch and meant for lighting circuits not electric motors.

For a bandsaw, you want:
http://www.mcmaster.com/#standard-motor-switches/=hqmw9q
Indoor enclosure single phase manual motor switch. McMaster part #7657K31. $34.60

There are also magnetic starters at the bottom of the page which are great for overload protection but are a bit challenging to wire if you don't have a lot of electrical experience.

[Rod Sheridan]

Regardless of what type of switch you purchase, it must be marked with a horse power rating to be used as a motor starter. You will need a switch rated for 240 volts and 3 HP (minimum).

The other issue is that motors require overload protection, either built in, or provided via the motor starter.

Check the nameplate on your motor, if it doesn't say "Thermally Protected" or words to that effect, you need external overload protection for your motor.

Please reply back with the motor current rating in amperes, and whether your motor is internally protected or not.

Regards, Rod.

[Michael W. Clark]

Regardless of what type of switch you purchase, it must be marked with a horse power rating to be used as a motor starter. You will need a switch rated for 240 volts and 3 HP (minimum).

The other issue is that motors require overload protection, either built in, or provided via the motor starter.

Check the nameplate on your motor, if it doesn't say "Thermally Protected" or words to that effect, you need external overload protection for your motor.

Please reply back with the motor current rating in amperes, and whether your motor is internally protected or not.

Regards, Rod.

Some of the switches from HD are horsepower rated, but Rod makes a good point about the overload protection. If the motor doesn't have this, you probably need something like Rod or Peter is recommending.


Mike

[Michael Menzli]

Thanks for the great feedback guys,

The motor is rated at 12.26 amps 14.2 sf amps 230 volts The motor does not list tefc but it has a circuit reset unit mount on it..basically a little red switch ..Im assuming this is what you guys are referring to?

This will be the only machine on this circuit.

I purchased and installed a 20amp double pole breaker with 12/2 wire . http://www.lowes.com/pd_13317-296-HOM220CP_0__?productId=1013949&cm_mmc=SCE_gps-_-gps-_-gps-_-Square%20D%20Homeline%2020-Amp%20Double%20Pole%20Circuit%20Breaker&CAWELAID=1367969726

I then installed this : http://www.lowes.com/ProductDisplay?partNumber=92606-296-L211N&langId=-1&storeId=10151&productId=3365260&catalogId=10051&cmRelshp=req&rel=nofollow&cId=PDIO1 using 2 20amp slow blow fuses .. tested and I have 240 at the breaker.

From the breaker I want a "power switch" for the saw itself. Right now I want something local to determine if the motor will even work with the saw frame. Ive read where 3hp may be too much torque on a cheap HF frame. The wheels are cheap aluminum 14" . I do have a new link belt.

I bought this : http://www.lowes.com/pd_73267-334-3032V-SP-L_0__?productId=1099531&Ntt=double+pole+switch&pl=1&currentURL=%2Fpl__0__s%3FNtt%3Ddouble%2Bpole%2Bswi tch&facetInfo=

I actually found what I needed wiring wise... One side will be my power from the box..the other power to the motor.

I too have 2 little ones (4yr and 5 mth) and will use the breaker on the wall every time. My Power switch will also be up on the wall out of reach.

[Rod Sheridan]

Hi Michael, that switch is only rated at 2 HP so it's not large enough for your motor.

Did you determine if the motor has built in thermal protection?

Regards, Rod.

[Michael Menzli]

Hi Michael, that switch is only rated at 2 HP so it's not large enough for your motor.

Did you determine if the motor has built in thermal protection?

Regards, Rod.


Hey Rod,

thanks for the followup.. I saw after posting that it was rated at 2hp. What is the issue with using one designed for less power? Does these get overheated ?

secondly the only thing i can find on the motor is a circuit breaker type unit. Basically it looks like a push button reset circuit ..not sure if this functions as a thermal protection or not..but assume no.

I did do a dry run last night..simply hardwiring to my "throw box" . The motor powered up, but almost too fast..it scared me ..not sure if this is typical of the motor , 240 or what....I can say the power down was fairly fast as well which I like a lot.. no vibration to speak of and very quiet. Id say its smoother then the original but have not installed a blade yet.

Im curious are there issue with simply using this throw/fuse box as my on off power? I have the secondary breaker at my main panel? If I do wire the switch Ill basically have 3 circuit breakers for one motor?/

[Rod Sheridan]

Hi Michael, the main issue with HP ratings on switches is to handle the learge starting currents without welding the contacts together.

Nothing so exciting as a machine you can't turn off.

The push button reset is the thermal overload for the motor, so you don't have to provide that in your starter.

I would go to a local electrical supply place and see what they have in manual motor starters, without overload protection..............Regards, Rod.

[Salem Ganzhorn]

I like these switches: http://www.grizzly.com/products/h8243

[Van Huskey]

By the way regarding 3hp vs the frame of the saw: the single link belt won't transmit nearly all the power of that motor so even if the torque could damage the frame I suspect the link belt would slip first.

[Michael Menzli]

Thanks for that info Van. Was not aware of that. I got everything hooked up and have the saw simply hardwired to my circuit interrupt box for the time being. I plan on returning the current switch and purchasing one of those recommended . I can say I am pleasantly surprised with the change. I havnt noticed anything abnormal...with the saw vibrating even less than before. My only fear is how fast this bad boy starts. Its almost like this huge jolt of power. I know I sound very ignorant but cant think of how else to describe. Im assuming thats the 240 piece.

I did a quick 4 inch resaw on some sycamore. Everything was smooth as silk with no "bogging" or strain .

I did come across a minor issue. I discovered that the dang motor is 3450 rpm.. The original pulley had 4 "speed" settings. I currently have it set at the 1140 pulley (1750 rpm) and assume with the 3450 rpm this is simply doubled to 2280.. Is this correct? The blade Im using is a Timberwolf 3/4" 2-3tpi . Would I be okay to jump up to the next speed of (1670) 3340 ? Are there any pro's or cons to doing do? Ill be doing a majority of simple 6x6x3 or 6x6x4 bowl blanks and occasional pen and larger bowls.. I plan to do some resawing down the road..probably 8" high

[Michael W. Clark]

Yes, the pully combination speed at 1750 RPM would be increased by the ratio of the new motor speed to 1750 RPM (3450/1750=1.97) The "1140" RPM combination would actually be at 2247 RPM. As far as if this is the correct speed for what you are doing, others can probably answer that better, and in terms of blade speed. You'll have to back calculate your blade speed based on the speed of the pulleys and diameter (circumference) of the saw wheels.

For simplicity, put the belt on the pulley combination rated at half the speed of the combination you operated with the 1750 RPM motor. The 3450 RPM motor supplies less torque of a 1750 RPM motor of the same HP (but higher RPM), so using more reduction after the motor gives you better torque to turn the saw wheel. This gives you less stalling unless the blade slips on the wheels or link belt can't carry the load, as Van said. Think of it like 4WD low versus 4WD high. Same HP motor, more torque in low range (less RPM, more gear reduction).

Mike

[Van Huskey]

I would run it on the 1670 fpm pulleys to give you ~3200fpm, UNLESS this introduces too much vibration. For wood it is nice to be above 3000fpm in most situations.

[Michael Menzli]

Thanks guys.. Got everything up and running now. I went ahead and moved the belt up to the next setting. I didnt see any added benefit in moving it up really. I was hoping the feed rate may go up but it really stayed the same. I actually found it to be a little less overall as now when cutting I get a nice screech as it slices the wood vs. quiet with the slower setting.. So I will be switching that back.

So far so good. I havnt noticed anything substantial with the upgrade outside of this seeming more "efficient" persay. The saw seems to cut with less effort and I dont sense any bogging or slowing even if I force just a bit. No vibration and Id say maybe even less then the original motor..this motor seems quieter overall...

I did learn a lot which is always cool ...I can say Im a little more comfortable with 240 now but still have a ways to go. Thanks a ton for all the great feedback and lack of ridicule which I see at times. You guys have been great!

[Van Huskey]

I didn't go back through to see if you mentioned the blade you are using, the extra speed will NOT increase feedrate unless the blade has sufficient gullets to handle the increased chip load. So if/when you use a deep gullet aggressive blade for resawing or ripping you may retry the higher speed, probably with better results.

[Salem Ganzhorn]

I am not sure what the limiting factor is for cutting wood but I would use the lower speed set of pulleys for sure. The old motor was half the speed of the new one right?

Thanks for posting your info. Previously I thought about upgrading a BS motor but didn't because the higher HP 1750rpm
motors are more expensive then the 3450rpm motors. It is. I nice to hear a data point that it can work.
Salem

[Van Huskey]

I am not sure what the limiting factor is for cutting wood but I would use the lower speed set of pulleys for sure. The old motor was half the speed of the new one right?

Thanks for posting your info. Previously I thought about upgrading a BS motor but didn't because the higher HP 1750rpm
motors are more expensive then the 3450rpm motors. It is. I nice to hear a data point that it can work.
Salem

Optimum wood cutting speed is above the capability of most 14" saws, vibration due to wheel balance and lifting of the unglued tires. You will find larger old iron saws even above 9000sfpm! I find that optimum blade speed for wood cutting is 4,500-6,000 sfpm. Louis Iturra recommends "supercharging" a 14" saw to 4,000 sfpm but that may require tight urethane or glueing the rubber tires. In the end I think the best choice for this saw is the pulleys that give ~3200fpm but feedrate and finish will only increase with the correct blade. BTW finish also goes up with increased band speed.

[Michael Menzli]

Thanks for the followup Van.. Im using a Timberwolf 3/4" 3 tooth. I have resharpened it once so its not as new. I have installed urethane tires from Peachtree. Not sure how they compare to others but these seems legit and a nice upgrade..WAY better than a cheap rubber that came original.

Ill try and sharpen the blade a bit more and bump up the speed for giggles again.

I am satisfied Salem. There was some minor work involved but with some of the help on here it went very very smoothly. I will say the bigger motor was much heavier so I ended up with a floor jack to lift and stabilize it. I too was concerned about the 3450 but once I found I could get buy with my pulley options I pulled the trigger. This bigger motor as stated is just smoother overall with no "bogging" or binding. Just slides through the wood where the smaller may shut off intermittently... I did test it out on some 8" wet maple last night.(basically half a log) It was slow going but never skipped a beat or bogged for a second. Id feel real good about pushing it to 10" but the saw may not :)

[John R Hoppe]

Having worked in the electrical/electronics business most of my career, I find that it is better to get knowledgeable help than to "give it a try" and possibly have things go wrong. An electrical motor is an "inductive load" and as such can store a great deal of energy that is released when breaking the circuit (turning the switch off) and will arc across the switch contacts, quickly destroying a switch not designed for motor loads.

The OP's question needs to be set up correctly to work without possibility of electrocution or fire and to do that a secondary contactor or "Motor Starter" is needed to run that 3 HP motor. Since the motor requires 240VAC and will draw approximately 15 amps, you will need a breaker and circuit wired for 240VAC and 20 amps available to connect the saw. You will also need to find a motor starter rated for at least 3 HP at 240 VAC and with an operating coil voltage of 120 VAC. Next, the existing switch on the saw (assuming it is SPST with 2 wire connections that break the circuit) can be used to control the power going to the coil on the motor starter. In the drawing below, the 120 VAC is picked off of L1. The L1 and L2 wires are also connected to the contacts of the motor starter and will go through to the motor on the saw. The neutral wire is connected to the "ground" point on the motor, and also to starter coil as shown.

An even better solution would be to get a "magnetic switch" to use in place of the saw switch to operate the motor starter. A magnetic switch uses a relay to hold it's contact closed and a second contact to release. It is set up internally so that if power is removed and reapplied the switch will automatically open, preventing unintentional starting of the motor when the power comes back on.

In any case, if you are even slightly unsure of you ability to do this correctly, please hire a licensed electrician who has knowledge and experience with motors to set this up for you.