125lb Fairbanks

[thecelticforge]

I am looking into buying a 125 lb Fairbanks hammer. The site says that it requires a 2 hp motor. What kind of wiring will I need for this. Also, what kind of footing underneath it? The price is so sweet, I gotta snatch it up even though it is larger than I will ever need.

[nonjic]

I know 'mechanicals' are pretty efficent machines, but 2hp sounds very low to me for a 125lb machine... I think my hoover is 1500w :blink:

[monstermetal]

That is 2 hp at 900 rpm which is about the same size motor as a 5 hp 3450

And a 125 lb hammer is a great size. Not the least oversize for day to day work. I'd snatch it up. The Fairbanks machines are really nice

[thecelticforge]

I just got off the phone with a guy in PA that the power hammer page on anvilfire listed. He was not the nicest person I have ever spoken with. He actually demanded to know how I got his #, when it is posted on several power hammer pages. I am glad the machinist if a my friend..

[Nakedanvil - Grant Sarver]

That is 2 hp at 900 rpm which is about the same size motor as a 5 hp 3450

And a 125 lb hammer is a great size. Not the least oversize for day to day work. I'd snatch it up. The Fairbanks machines are really nice

Yeah, but it's still 2 HP!

[Dave Hammer]

The data sheet at the following link say 2 HP is correct. If it is a low HEAVY low RPM motor, it should work OK. The motor should have a plate that states what voltage it needs (and what amperage it may draw at startup).

http://www.fairbanks.forginghammers.com/cfair_specs.htm

[nonjic]

It just sounds low to me..... 2 horseys is still 2 horseys, put a racehorse on a treadmill and it can pull a cart same as a clydesdale, its still 1 horse power :)

[thecelticforge]

It just sounds low to me..... 2 horseys is still 2 horseys, put a racehorse on a treadmill and it can pull a cart same as a clydesdale, its still 1 horse power

ummm, I spent years on the track and I can assure you, that the race horse can't pull as well as a clyde. Especially if he is on a treadmill. He won't go anywhere. B)

[Ranger604]

There should be a plate on the motor stating the voltage and amps. There are 2HP motors that are 110,220 ,208 single phase and triple phase. if there is no plate, buy a new motor. It will cost you 100 to 300 bucks. Depends on the HP and voltage and phase. Safe..not sorry. zzzzaaappppp!!!

[Dave Hammer]

If you have a 2HP motor, use it. If it's anemic, replace it. If you don't have a motor, buy a larger one. DO look for a low RPM HEAVY motor.... The heavier the motor, the better....

A HP is not a HP is not a HP. Not all HPs are created equal.

As far as advice for a foundation, do you know where you are going to put the hammer? What type of floor does the building have? If it has a concrete floor, how thick is it? If the floor is concrete and at least 5 inchs thick, you could probably just put a wood base (4 inches thick or so) under the hammer, then epoxy anchor bolts into the concrete. Doing it this way, however, may cause enough vibration and rattle stuff off shelves. If you want the best case, use a concrete saw and cut out a space in your floor, maybe 30 x36 inches, then dig a hole 30 inches deep and fill it with concrete (with rebar reinforcement). Isolate the foundation from the floor with two tar spacers (like they use on sidewalks). Let it cure 30 days, then still use the wood base and anchor bolts.

If you don't know how thick your floor is, just drill a hole under where the hammer will be with a masonary bit... When it breaks through the floor, you will know.

[thecelticforge]

I am loving all this advice, keep it a coming!

[monstermetal]

Yeah, but it's still 2 HP!

Um.... no

A 2HP 3450 motor is going to make around 3 ft/lbs of torque.... a 2 HP 900 rpm is going to make around 11 ft/lbs of torque

motor info chart

Thats why a low rpm motor works so much better for a hammer, at the speed the hammer needs to run its actually got some umph... Didnt you ever wonder why low RPM motors are so huge? a 5hp 900 motor makes the same torque as a 10 HP 3450 and torque is what is doing the work on a hammer

[E.F. Thumann]

I'm just completing a 2-year (get off my case, I'm busy, lol) re-build of a 125 Fairbanks Model D. Machined new bronze bearings, acid-washed/etched the hammer, re-painted, etc. (she's a beaut, what's better than 100 year old machinery?) I just bought a 7.5 hp, 1100 rpm motor to run it. Although I'm honestly thinking of selling it with the motor once I get the last bits and pieces painted........hmmmm.............

[Nakedanvil - Grant Sarver]

Um.... no

A 2HP 3450 motor is going to make around 3 ft/lbs of torque.... a 2 HP 900 rpm is going to make around 11 ft/lbs of torque

motor info chart

Thats why a low rpm motor works so much better for a hammer, at the speed the hammer needs to run its actually got some umph... Didnt you ever wonder why low RPM motors are so huge? a 5hp 900 motor makes the same torque as a 10 HP 3450 and torque is what is doing the work on a hammer

That is absolutely right! But in order to drive the hammer, you need a 900 rpm driving pulley. So you put in a jackshaft with a 4:1 ratio which cuts the rpm to 900 and multiplies the torque by 4 which equals 11 - 12 foot pounds at 900 rpm. You're always going to have to "gear down" the faster motor for the same hammer rpm. Lower gearing multiplies the torque. 2hp is 2hp.

[Nakedanvil - Grant Sarver]

That being said, a 900 rpm motor is certainly more convenient. I was just speaking to the fact that 2hp = 2hp.

[Fosterob]

Is the amp draw on a 2hp 900 rpm motor the same as the draw on a 2hp 3450 rpm motor? I would think to get the additional torque from the 900 rpm motor without gear reduction the amp draw would be how it gets the extra torque. It is getting late and past my bedtime, so forgive me if i am wrong here.
Rob

[Fosterob]

Posted to soon, If the amp draw is less on the 3450 rpm motor compared to the 900 rpm it would be cheaper to run the 3450 rpm motor and get the needed torque with gear reduction. Cost less money to turn the motor. Is this right?
Rob

[youngdylan]

A HP is not a HP is not a HP. Not all HPs are created equal.

A HP is a HP is a HP is a HP .... it's the amount of energy used per second .... how that enenergy is transmitted to its "intended" is a different matter

In a (non existant) ideal situation with no losses due to friction ANY motor of the right HP would do WHATEVER the speed, ]provided [/it was geared down/up appropriately with no losses. A HP is a HP ... 750 Joules of energy used per second.

[nonjic]

Sorry to raise the HP issue

If the original manual says 2HP thats good enough for me!

[Timothy Miller]

I ran a 75 lb Fairbanks for about 5 years. I used to run it with a 2 Hp 3 phase motor @ 1725 rpm with jack shaft to reduce the rpm down to something like 260 rpm. It ran well with the two hp motor but I would periodically over heat the magnetic starter and I would have to stop working to let it cool down. This was annoying when i had a blazing hot gas forge full of tool blanks. This only happened when I was running the machine flat out for several hours in warm weather. Ideally I think the machine should have had a 3 hp motor and it would have been unstoppable. I would guess the 125lb would use a 5 hp motor. Those Fairbanks hammers are very robust and simple and were meant to be ran hard. Many tool making shops used them up in new England. I liked that hammer very much until I got my Say-Mak then it suddenly looked like a quaint old machine.

[ThomasPowers]

I have an enormous ancient motor with my Champion. I inquired at the local motor re-builders about changing it out for a more modern one and they advised me to go with the old one till it stops working and told me that they would suggest replacing it with one that was 1.5 times the HP of the old one as the larger size provided a lot more torque the the new "small" ones of the same HP.

[youngdylan]

I have an enormous ancient motor with my Champion. I inquired at the local motor re-builders about changing it out for a more modern one and they advised me to go with the old one till it stops working and told me that they would suggest replacing it with one that was 1.5 times the HP of the old one as the larger size provided a lot more torque the the new "small" ones of the same HP.

possibly the new motors manufacrurers were being "economical with the truth" when giving HP figures or the old ones were being conservative with theirs.

HP essentially = torque multiplied by speed. If the speed is the same and losses in the motor are similar, torque should be more or less the same.

This website seems to go through the maths pretty well

http://www.elec-toolbox.com/Formulas/Motor/mtrform.htm

[monstermetal]

That being said, a 900 rpm motor is certainly more convenient. I was just speaking to the fact that 2hp = 2hp.

I know what your saying Grant... and the numbers support you.... But the real world I think is not that simple..... If you take a 3450 5HP motor and gear it down... what you have created is a mechanical means to put that speed to work.. the torque only exists if you can maintain the speed... and the sudden load of an engaging clutch on a hammer creates a condition for the motor that it is hard to recover from and very hard on the motor... a 2HP 900 RPM motor because it makes that same torque at the correct speed will absorb that load with no strain.... In a perfect world the gear reducing drive train would be 100% efficient, no slipping belts or loss and you would get the full HP of the higher RPM motor..

its true the amount of work in a HP is a constant.. so like you say a HP is a HP.... But I can stop my 1 HP 100,000 RPM die grinder with my fingers, without even trying at its rated speed it has no torque... If You tried to grab and stop the shaft of a 1 HP 900 RPM electric motor it would likely rip your arm clean off.... Its the torque that runs the hammer, and the torque is a linear relationship with HP at a given RPM... That 3450 RPM motor is still only producing 25% of the torque even if you have mechanical multiplied it though a gear train to 100% (theoretically) of the lower RPM motor, so the motor itself will only withstand 25% of the strain .....

But dont take my word for it.... Look at every Nazel or Chambersberg hammer... they all have low RPM motors... Motors that cost twice as much as a higher speed motor, Why would they spend twice as much on a low RPM motor if they could just gear it down and use a less expensive high speed motor? Because they would destroy a high speed motor subjecting it to those loads, Its about the torque and the ability of the motor to recover under load...

[youngdylan]

I know what your saying Grant... and the numbers support you.... But the real world I think is not that simple..... If you take a 3450 5HP motor and gear it down... what you have created is a mechanical means to put that speed to work.. the torque only exists if you can maintain the speed... and the sudden load of an engaging clutch on a hammer creates a condition for the motor that it is hard to recover from and very hard on the motor... a 2HP 900 RPM motor because it makes that same torque at the correct speed will absorb that load with no strain.... In a perfect world the gear reducing drive train would be 100% efficient, no slipping belts or loss and you would get the full HP of the higher RPM motor..

its true the amount of work in a HP is a constant.. so like you say a HP is a HP.... But I can stop my 1 HP 100,000 RPM die grinder with my fingers, without even trying at its rated speed it has no torque... If You tried to grab and stop the shaft of a 1 HP 900 RPM electric motor it would likely rip your arm clean off.... Its the torque that runs the hammer, and the torque is a linear relationship with HP at a given RPM... That 3450 RPM motor is still only producing 25% of the torque even if you have mechanical multiplied it though a gear train to 100% (theoretically) of the lower RPM motor, so the motor itself will only withstand 25% of the strain .....

But dont take my word for it.... Look at every Nazel or Chambersberg hammer... they all have low RPM motors... Motors that cost twice as much as a higher speed motor, Why would they spend twice as much on a low RPM motor if they could just gear it down and use a less expensive high speed motor? Because they would destroy a high speed motor subjecting it to those loads, Its about the torque and the ability of the motor to recover under load...

Larry is not another major reason for using low rpm motors that a with a high rpm motor there would be the extra cost of any speed reduction/ torque multiplication. Also there would be the considerable "real world" loss of the reduction sytem, more bearings to grease maintain or fail, more moving parts etc. If you could ever get such a thing as a " loss less" speed reduction and use it with that 100000rpm die grinder to reduce the speed to 900 rpm, the output shaft of the speed reduction would also rip your arm off.

In the case you mention above, the strain you mentioned is also reduced by 25% on the input shaft of the speed reduction, the motor only needs to deal with 25% of the strain. Its why the shaft diameter on high speed motor is much less than low speed motors of the same HP.

Reduction gearing works two ways, it increase the output torque and reduces the mechanical "load" the motor sees by the same proportion

Any odds, my treastise is all rather irrrelevant in the real world, it makes sense to use as low an rpm motor as possible for many reasons (but eevn that 900 rpm still has to be reduced by the hammer). Alls I'm saying is a HP is a HP ...... on paper.

[youngdylan]

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