VFD and bandsaw success
 

I have Jet brand 14 inch vertical bandsaw that's a knockoff of a Delta
saw. The saw label says it's a wood/metal cutting saw. But even with
the extra pulley set on a jackshaft the lowest speed was still way too
fast to cut steel. The solution I picked is a 1 hp 3 phase 1725 rpm
motor and a VFD. The VFD is connected to 220 volt single phase. With
the belt and pulley combination set up for the lowest RPM and the VFD
set for 120 Hz max the saw will go fast enough for wood cutting and
slow enough for steel cutting. Since the belts are set up for the
lowest speed the smallest diameter pulleys are being used so the
friction between the belt and the small pulleys is not quite enough to
prevent slipping when I put too much pressure on the blade when sawing
steel. I'll try a segmented belt and if that doesn't work then I'm
going to use a toothed belt. But since it only slips once in a while
the priority for this fix is low. Other than that the VFD controlling
the saw speed works very well and because of that the big horizontal
band saw is now slated for the same conversion. No more changing
belts!
ERS

VFD and bandsaw success
 

Eric R Snow wrote:

I have Jet brand 14 inch vertical bandsaw that's a knockoff of a Delta
saw. The saw label says it's a wood/metal cutting saw. But even with
the extra pulley set on a jackshaft the lowest speed was still way too
fast to cut steel. The solution I picked is a 1 hp 3 phase 1725 rpm
motor and a VFD. The VFD is connected to 220 volt single phase. With
the belt and pulley combination set up for the lowest RPM and the VFD
set for 120 Hz max the saw will go fast enough for wood cutting and
slow enough for steel cutting. Since the belts are set up for the
lowest speed the smallest diameter pulleys are being used so the
friction between the belt and the small pulleys is not quite enough to
prevent slipping when I put too much pressure on the blade when sawing
steel. I'll try a segmented belt and if that doesn't work then I'm
going to use a toothed belt. But since it only slips once in a while
the priority for this fix is low. Other than that the VFD controlling
the saw speed works very well and because of that the big horizontal
band saw is now slated for the same conversion. No more changing
belts!
ERS

Machinery's Handbook has a good section on how much energy can be
transmitted through a belt/pulley system before the belt slips. The easiest
solution to your slip issue is to switch the pulleys to one which uses two
belts. You'd probably lose the ability to change speeds with the belt but then
you weren't going to use those anyway.

Those "wood metal" saws have a lowest cutting speed of about 800 sfm, which is
OK for some soft nonferrous metals like aluminum.

It's good to see something new on a thread which has been recurring in various
ways for nearly 100 years now, first in places like Popular Mechanics, and in
the last 30 years in various metalworking magazines, and in the last 10 years on
this NG.

I'm curious how much your total cost was, Eric?

Grant

VFD and bandsaw success
 

On Fri, 27 Jul 2007 10:45:20 -0700, Grant Erwin
wrote:

Eric R Snow wrote:

I have Jet brand 14 inch vertical bandsaw that's a knockoff of a Delta
saw. The saw label says it's a wood/metal cutting saw. But even with
the extra pulley set on a jackshaft the lowest speed was still way too
fast to cut steel. The solution I picked is a 1 hp 3 phase 1725 rpm
motor and a VFD. The VFD is connected to 220 volt single phase. With
the belt and pulley combination set up for the lowest RPM and the VFD
set for 120 Hz max the saw will go fast enough for wood cutting and
slow enough for steel cutting. Since the belts are set up for the
lowest speed the smallest diameter pulleys are being used so the
friction between the belt and the small pulleys is not quite enough to
prevent slipping when I put too much pressure on the blade when sawing
steel. I'll try a segmented belt and if that doesn't work then I'm
going to use a toothed belt. But since it only slips once in a while
the priority for this fix is low. Other than that the VFD controlling
the saw speed works very well and because of that the big horizontal
band saw is now slated for the same conversion. No more changing
belts!
ERS

Machinery's Handbook has a good section on how much energy can be
transmitted through a belt/pulley system before the belt slips. The easiest
solution to your slip issue is to switch the pulleys to one which uses two
belts. You'd probably lose the ability to change speeds with the belt but then
you weren't going to use those anyway.

Those "wood metal" saws have a lowest cutting speed of about 800 sfm, which is
OK for some soft nonferrous metals like aluminum.

It's good to see something new on a thread which has been recurring in various
ways for nearly 100 years now, first in places like Popular Mechanics, and in
the last 30 years in various metalworking magazines, and in the last 10 years on
this NG.

I'm curious how much your total cost was, Eric?

Grant
Greetings Grant,
I knew that the small pulley was marginal and I know about Machinery's
Handbook power transmission data but it doesn't hurt to try. The cost
was about 100 bucks for the VFD and 5 bucks for the motor. I got a
screaming deal on some 14/2 with ground SO cord from Home Depot so I
can't say what a cord would cost from someone else. The plug and
receptacle cost close to 20 bucks for the pair because I use
twistlocks for all my machines. If the cost was $200.00 it would
still be worth it though just because it makes the saw so much more
versatile. Changing the speed to EXACTLY what works best saves tons of
time. Just turning the knob is so easy and fast.
ERS

VFD and bandsaw success
 

Eric R Snow wrote:
... it makes the saw so much more
versatile. Changing the speed to EXACTLY what works best saves tons of
time. Just turning the knob is so easy and fast.

Boy, I know that feeling! It's so satisfying, isn't it? For me, it's
the drill press, but the idea is the same - turn the knob until you get
the speed you like.

Bob