Home Model Engine Machinist > The Tools and Tips > Tools > Calculating the speed of a bandsaw blade -- Need help
Reply
 
Thread Tools Display Modes
Old 01-03-2011, 09:41 PM   #1
xo18thfa
 
Join Date: Feb 2009
Posts: 239
Liked 24 Times on 24 Posts

Default Calculating the speed of a bandsaw blade -- Need help

I just bought a 14" Rigid brand bandsaw from Home Depot. The spec sheet says that the blade speed is 2700 feet per minute. When I assembled the machine and turned it on for the first time, it seemed the blade was going a lot faster then 2700 FPM. I did some math and came up with a blade speed much much higher then 2700.

Request members of the HMEM board independently do the math to see if I am off. Here are the specs:

Motor speed, no load: 1725 RPM
Pulley diameter on the motor: 2"
Pulley diameter on the bandsaw shaft: 5.5"
Blade length: 93.5"

Many thanks in advance, Bob



__________________

Bob Sorenson
Las Vegas, Nevada

xo18thfa is offline  
 
Reply With Quote Quick reply to this message
Old 01-03-2011, 10:10 PM   #2
imagineering
 
imagineering's Avatar
 
Join Date: Dec 2010
Posts: 77
Liked 5 Times on 5 Posts

Default Re: Calculating the speed of a bandsaw blade -- Need help

Hi Bob,
We would also need to know the Diameter of the Blade Drive wheel so you could calculate;

Motor Rpm / Pulley Ratio = Drive Wheel speed
Therefore; 1725 rpm / 2.75:1 = 627.27 rpm, (divided by, as the Ratio is geared down).

627.27 X Circumference of Driving Wheel = Blade Speed
Assuming, (for the sake of this equation), 12" diameter, (6" Radius), Drive Wheel, (which is probably wrong for this Machine)
627.27 X 37.699" (2PiR) = 23647.45Ipm (1970.6 Fpm)


This Calculation assumes no Blade slip on the Drive Wheel - The Blade length is irrelevant.

Murray



__________________

Wellington,
New Zealand.

imagineering is offline  
 
Reply With Quote Quick reply to this message
Old 01-03-2011, 10:34 PM   #3
AR1911
 
Join Date: May 2010
Posts: 61
Liked 2 Times on 2 Posts

Default Re: Calculating the speed of a bandsaw blade -- Need help

Look at KMOT's gizmo he just bought from HF.

http://www.homemodelenginemachinist....?topic=12164.0

Looks like what you need for this.

__________________
AR1911 is offline  
 
Reply With Quote Quick reply to this message
Old 01-03-2011, 10:38 PM   #4
Dan Rowe
 
Dan Rowe's Avatar
 
Join Date: Feb 2010
Posts: 591
Liked 31 Times on 30 Posts
Likes Given: 5

Default Re: Calculating the speed of a bandsaw blade -- Need help

Bob,
Using the logic provided by Murray and using 7" for the radius of a 14" band saw I get 2299 Fpm.

Edit: I had to fix the math.

Dan

__________________
Dan Rowe is offline  
 
Reply With Quote Quick reply to this message
Old 01-04-2011, 12:59 AM   #5
xo18thfa
 
Join Date: Feb 2009
Posts: 239
Liked 24 Times on 24 Posts

Default Re: Calculating the speed of a bandsaw blade -- Need help

Quote:
Originally Posted by imagineering
Hi Bob,
We would also need to know the Diameter of the Blade Drive wheel so you could calculate;

Motor Rpm / Pulley Ratio = Drive Wheel speed
Therefore; 1725 rpm / 2.75:1 = 627.27 rpm, (divided by, as the Ratio is geared down).

627.27 X Circumference of Driving Wheel = Blade Speed
Assuming, (for the sake of this equation), 12" diameter, (6" Radius), Drive Wheel, (which is probably wrong for this Machine)
627.27 X 37.699" (2PiR) = 23647.45Ipm (1970.6 Fpm)


This Calculation assumes no Blade slip on the Drive Wheel - The Blade length is irrelevant.

Murray
Wheel dia is 14"
__________________

Bob Sorenson
Las Vegas, Nevada

xo18thfa is offline  
 
Reply With Quote Quick reply to this message
Old 01-04-2011, 01:12 AM   #6
MachineTom
Senior Member
HMEM_SUPPORTER.png
 
MachineTom's Avatar
 
Join Date: Oct 2010
Location: Jersery Shore, USA
Posts: 726
Liked 94 Times on 69 Posts
Likes Given: 6

Default Re: Calculating the speed of a bandsaw blade -- Need help

Well at 2300-2700 sfpm what you need is a speed reducer of about 1:40 to cut steel. It takes all the fun out of a great deal like that, to need to come up with a speed reducer to make it work.

__________________

My Wheels don't slow me down

MachineTom is offline  
 
Reply With Quote Quick reply to this message
Old 01-04-2011, 01:27 AM   #7
xo18thfa
 
Join Date: Feb 2009
Posts: 239
Liked 24 Times on 24 Posts

Default Re: Calculating the speed of a bandsaw blade -- Need help

I came up with 2299 now too, but in a different way. The drive wheel is geared down 1:2.75. So the drive wheel is turning 627 RPM. The drive wheel is 14" diameter or 44" circumference. That circumference makes a ratio of 1:2.125 on a 93.5" blade. So the blade is turning 295 RPM. 295 RPM x 93.5" blade = 27,582.5 IPM or 2299 FPM

I minored in math in college. It was "new math", no numbers, just Greek letters.

__________________

Bob Sorenson
Las Vegas, Nevada

xo18thfa is offline  
 
Reply With Quote Quick reply to this message
Old 01-04-2011, 04:56 PM   #8
mklotz
HMEM_SUPPORTER.png
 
mklotz's Avatar
 
Join Date: Aug 2007
Location: LA, CA, USA
Posts: 3,039
Liked 138 Times on 258 Posts
Likes Given: 2

Default Re: Calculating the speed of a bandsaw blade -- Need help

The length of the blade is totally irrelevant. The speed of the blade is the same as the surface speed of the blade drive wheel. (Were it not so, the blade would slip on the drive wheel.)

So we have:

SFPM = wheel circumference * RPM = (44/12) ft * 627 rpm = 2299 SFPM

The fact that your calculation uses the length of the blade proves it is wrong. Were I to replace the blade with one twice as long, the SFPM would remain unchanged yet your calculation indicates that it would double.

__________________

Regards, Marv

Home Shop Freeware
http://www.myvirtualnetwork.com/mklotz

mklotz is offline  
 
Reply With Quote Quick reply to this message
Old 01-04-2011, 09:42 PM   #9
xo18thfa
 
Join Date: Feb 2009
Posts: 239
Liked 24 Times on 24 Posts

Default Re: Calculating the speed of a bandsaw blade -- Need help

I see what I did wrong. I included blade length, then took it back out. It was a redundant step.

Thanks.



__________________

Bob Sorenson
Las Vegas, Nevada

xo18thfa is offline  
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Bandsaw Blade, Where do you get yours? multihobbyguy Questions and Answers 14 03-05-2011 07:55 AM
Bandsaw blade joining John Rudd Tips and Tricks 5 11-10-2009 10:18 PM
Bandsaw cutting speed question Brian Rupnow Questions and Answers 2 09-26-2008 08:51 PM
Give Your Parting Blade a Tune-Up, Plus Turning With a Parting Blade BobWarfield Tips and Tricks 1 05-04-2008 09:40 PM
Calculating bolt circle diameter mklotz Tips and Tricks 6 12-21-2007 05:58 PM

Newest Threads




- Top - Member List