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What is the max speed that you run a belt.
- Thread starter BrianThie
- Start date
Generally I go faster with coarser belts than I do with the fine ones. I use a Wilton variable speed and run it about 75% speed for general grinding and profiling.
When working with wood and more detailed and finishing work I run it less than 50% speed and often much slower than that.
When working with wood and more detailed and finishing work I run it less than 50% speed and often much slower than that.
- Joined
- Oct 18, 2001
- Messages
- 20,978
There seems to be some misinformation floating around as to actual belt speed. Best to clear this up...especially for the new guys out there.
SFPM (also sometimes refered to as just SFM) = Surface Feet Per Minute
SFPM is calculated using 2 variables: Motor RPM and Pulley Diameter
Here is the forumla:
[operating RPM] * [Pulley Diameter] * 0.262
The 0.262 comes from PI divided by 12
So, if your 1725 rpm motor has 4" drive pulley hooked up to it, then your SFPM is:
1725 * 4 * 0.262 = 1808 SFPM
Which isn't all the great.....and the reason why many folks use step pulleys and/or a larger drive pulley.
Ideally (and in my experience/opinion) a knife grinder should run up to 6000 SFPM and down to about 600 SFPM.
I use *both ends* of my VFD all the time. Mine goes up to around 5500 SFPM at 100% and I run it at 95-97% when profiling or flat-grinding at a rough grit (serious hogging). But I do find myself wishing I had just a *little* bit more at the top end.
I also slow it down to about 800 SFPM when using 400 grit belts and do wish I could go just a tad slower. My VFD does go slower...but it doesn't seem to want to run less than 15%....so, that's the *bottom end* of my SFPM.
Here's "My Chart" (taken from the first post)
Metals
60 grit = 70-95% = 3850-5225 SFPM
120 grit = 70% = 3850 SFPM
220 grit = 50% = 2750 SFPM
400 grit = 15-20% = 825-1100 SFPM
Handle materials
36 grit = 50-75% = 2750-3850 SFPM
120 grit = 30-50% = 1650-2750 SFPM
220 grit = 30-40% = 1650-2200 SFPM
400 grit = 20-30% = 1100-1650 SFPM
So, while the chart in the first post does overlap my personal findings in many ways....there is a bit of difference compared to my actual *real world* findings (based on my machinery/experience/preferences).
Others will certainly have different numbers...the above is just what I do in my shop.
Great question, though! :thumbup:
Dan
SFPM (also sometimes refered to as just SFM) = Surface Feet Per Minute
SFPM is calculated using 2 variables: Motor RPM and Pulley Diameter
Here is the forumla:
[operating RPM] * [Pulley Diameter] * 0.262
The 0.262 comes from PI divided by 12
So, if your 1725 rpm motor has 4" drive pulley hooked up to it, then your SFPM is:
1725 * 4 * 0.262 = 1808 SFPM
Which isn't all the great.....and the reason why many folks use step pulleys and/or a larger drive pulley.
Ideally (and in my experience/opinion) a knife grinder should run up to 6000 SFPM and down to about 600 SFPM.
I use *both ends* of my VFD all the time. Mine goes up to around 5500 SFPM at 100% and I run it at 95-97% when profiling or flat-grinding at a rough grit (serious hogging). But I do find myself wishing I had just a *little* bit more at the top end.
I also slow it down to about 800 SFPM when using 400 grit belts and do wish I could go just a tad slower. My VFD does go slower...but it doesn't seem to want to run less than 15%....so, that's the *bottom end* of my SFPM.
Here's "My Chart" (taken from the first post)
Metals
60 grit = 70-95% = 3850-5225 SFPM
120 grit = 70% = 3850 SFPM
220 grit = 50% = 2750 SFPM
400 grit = 15-20% = 825-1100 SFPM
Handle materials
36 grit = 50-75% = 2750-3850 SFPM
120 grit = 30-50% = 1650-2750 SFPM
220 grit = 30-40% = 1650-2200 SFPM
400 grit = 20-30% = 1100-1650 SFPM
So, while the chart in the first post does overlap my personal findings in many ways....there is a bit of difference compared to my actual *real world* findings (based on my machinery/experience/preferences).
Others will certainly have different numbers...the above is just what I do in my shop.
Great question, though! :thumbup:
Dan