Wisdom needed for picking out the correct motors

[BillyWitchDoctor]

hello, i am going to build a couple devices that will need electric motors of some kind and i know nothing about this subject right now. here is a very basic design of what i am building:

http://www.monumentaldesigns.com/images/roughPlan.jpg

i wonder if anyone could give their thought on what type of motors i would need to do this. i need them to be able to pull the blocks of foam through the cutter and i need to be able to adjust the speed with some sort of knob. also im not too sure about the gears that actuall pull the block through.

thanks for any ideas.

 

[laundry]

Hi BillyWitchDoctor
Looked at your design, are you going to put flat belts from front to back, so that your foam will be pulled through streight.If this is what you had in mind you could use one 0.37kw motorgaerbox to give the correct speed required,and then use an inverter for fine tuning of your speed.I would drive the other side through a small v belt off your gearbox output shaft.All dimentions will have to be the same on ether side,so that one side is not running faster than the other.I have used a motor of 0.37kw as a guid only but looking at your design it looks very light duty

Barry.

 

[Barry1961]

It will depend on how much force you need to push the block thru the hot wire and how fast you are pushing. If it took 10 pounds of force and you wanted to move at 30 feet per minute/ 6 inches per second and you had 2” OD drive rolls/gears and you use a standard 1725 rpm motor.

force(lb)* velocity(fpm)/33,000 = horsepower
10lb * 30fpm/33,000=.009 horsepower

30fpm=6 in-sec
2" OD drive gear
2" * PI = 6.28" cir, the block will move 6.28” per revolution.

6/6.28= .955 revs per sec to travel 6 in-sec
.955 revs per sec x 60 = 57.3 revs per min(rpm)

1725 rpm(motor)/57.3 rpm = 30
You would want a gearbox with a 30:1 reduction between motor and drive roll.

There are other factors that may require more horsepower such as gearbox efficiency, running motor at low or high speed, start stop and loss in drive train.

You can get a little 1/30 hp, 30:1 that will produce 58 in-lb of continuous torque. A 2” OD drive roll has a 1” radius so you would have the potential of 58 lbs of push before any losses. The gear motor would probably run you about $130 and a VFD to run it about $130.

If you double the speed you double the horse power, same with force.

Barry1961

 

[itsmoked]

BillyWitchDoctor; laundry is right on. You want to run all those with one motor! The design is a shoe-in for that too, since you have the "great underneith".

And Barry1961 has the numbers you need. Looking at your design I would imagine everything is based on how much abuse the wire can take.

To figure out your motor needs you could pull the block thru the wire with a spring scale up till the wire starts to get annoyed. This would give you a good power "required" figure. You'd then want to add a little for robustness.

 

[BillyWitchDoctor]

hey thanks alot guys!
your input is much apreciated and this will help me get going but im sure ill be back for more.