Help with specifying?

[christwit]

My company produces some lumber products that require us to drill 1 1/2" deep holes 5' deep. Currently we do it by using hand held drills, which is our bottleneck. We looked at using a Milwaukee Core motor(4096), which is extremely close to what we are looking for but lacks the torque(162 ft/lbs) to fully accommodate our needs. We have have a extremely small work area and we need to operate 5 of these simultaneously. While gear reduction is an option, I would prefer to use the motor directly. Ideally, what I'm searching for is a 3 phase motor, that has a drive rpm of 700-900(faster will exceed the capabilities of our drill bits), while maintaining aprox 250 ft/lbs of torque.

Perhaps I'm asking in the wrong place, but maybe someone can help steer me in the right direction. Any help would be appreciated.

Thanks,
Chris

 

[sreid]

250 lb-ft at 900 RPM is 43 Horsepower. The Milwaukee Drill is rated at 4.8 HP so something is wrong. Is it possible that the torque figures are wrong?

 

[christwit]

My apologies, I was going off some other information I got. I'm assuming that this equation is valid for this so let me know if I'm off base.

HP = (Torque x rpm) / 5250

4.8 = (T x 900) /5250

T = 28.

So currently, based off of that I'm currently at 28 lb-ft, and would like to achieve 40~.

 

[sreid]

That looks right now. 40 lb-ft at 900 RPM is 6.8 HP. I would suggest a 5 HP, 900 RPM AC induction motor. The motor can be overloaded assuming that the duty cycle is not 100%. This will not be a cheap solution; Baldor's list price is about $2000. It also requires 3 phase power (however the core motor is 20 amps which will probably require a new AC service). But you can probably rip holes for the next 20 years without problems. The core motor is certainly a universal motor which will qickly go through brushes in a production environment.

 

[itsmoked]

You might consider a gear box and 3450RPM motors as that may be lighter and could allow higher inertia availability if the drill process has any jerking in it. Use a rated timing belt around two cog pulleys.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[christwit]

Many thanks for the replies. Just me researching the equation for torque led me in the right direction. I did find a Lesson 7.5 horse, 850 rpm motor that I think I can purchase for $1400. This is generally beyond my lowly lumberyard workers intelligence limits, so I will likely be back with some more questions.

Thanks again,
Chris