In the process of making my 3 wheel bandsaw. I am wanting to use a DC
motor of 1 1/2 hp with a speed controller, but would like to add a
jack shaft. as well, just to make sure I can keep up the torque on the
saw at the necessary speeds needed for general metal cutting. The
motor I have is 1 1/2hp Leeson Electric, (removed from a typical
treadmill) and runs up to 5120 rpm and pulls 15 amps. The controller
I have for it is made by Dart and is supposedly capable of handling up
to a 2 HP motor. I understand this controller is supposed to be able
to keep the motors torque up at low speeds, but I would not bet my
life on it. Guess I am just paranoid, as I do not have to much
dealings with DC motors and controllers.

So what ratios would I need to go with to get the saw down to useable
speeds for metal cutting? (Looking for 65 to 550 SFPM from what I
have found out in regards to speed), although it would be nice to
jack it up in speed for wood cutting.

Would I be better off initially reducing the speed with a gear reducer
that drives a jackshaft and then the saw or what? Or should I still be
able to get by with just a 4:1 ration jackshaft and rely on the speed
controller to do its job?

So far except for this problem, the project is going fine. I have one
more wheel (drive wheel) yet to cast and machine, shuld have my tires
next week, have the caster / camber tension assembly made, starting to
work on the blade guides. This brings anopther question to light. Lots
of saws today use simple ball bearing for guides. They seem to last ok
on my H/V bandsaw, but have a habit of allowing lots of crub get by or
get beat into the bearings or blade, so I was thinking on using some
guides similar to what DoAll uses. Is there any materials out there
that I can machine in a home shop thatw ould serve usefull in making
these guides. They need to work with 3/8" at a minimum to no more
than a 3/4" blade. Buying those Cool Cut guides is out of the
question, so I need to come up with a home brew deal. I was also
thinking of using a small engine valve tappet (like found in B & S
engines) that runs in a bushing and is adjustable in and out with a
setscrew. Any other ideas greatly appreciated.

Presently I have just the basic shape of the frame laid out and am
concentrating on making all the actual working parts, so I can juggle
things here and there, and the frame will be built around these last.

Looks like it will have a 17" + - 1" throat size, 8 1/2" to 9" cutting
height, stand 71" tall, have a width of 29" and be 8 1/2" in depth,
take a 107" blade is usiing the three wheels or a 86" blade if
utilizing just two wheels. Table size 20 x 22.

The table is still one item that I need to dio a bit of thinking on. I
wiuld like to be able to mill it out so I can use a push type rip
fence so it looks like a piece of steel plate or perhaps 1/2"
thickness is in order, so if anyone has any other suggestions on a
table they would also be appreciated. I already have a mitre / rip
gauge from a large Delta belt / disk sander that I would like to use.
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Wood speed is something like 2000 to 3000 fpm or 5 times what you
need for metal. If you want to do wood, I'd suggest some sort of
belt deal to switch back and forth. You would need to change
blades also so why not just make a big deal out of it and do it
right.

You want the 5120 to match up with 565 fpm. You didn't say what
size wheels you plan but assuming 14" or so you will need about
150rpm on the shaft or a 34 to 1 reduction. Only thing that will
do that in one step is a worm drive. I'd suggest a belt reduction
of about 6 or 8 with a gear reduction of 4:1 or 5:1. You might be
able to use the gear reduction bearings for the drive pulley mount.

For 1-1/2 hp, the smallest v-belt drive pulley you should use is
2", 2-1/2" is better. Go smaller and you will have slippage and
excessive belt wear. Assuiming you can even get a 12" pulley,
that means a maximum of 6:1 reduction in a single V-belt
recuction. 2x on this would be 36 to 1, about where you want to
be. You can source the large pulleys at a farm store, they have
an array of hubs, plus an array of wheels, weld them up. Sounds
awful, works fine, about $16 for a 12" pulley in your choice of
hub sizes. If you still want to do wood, use 1 reduction for
wood, 2 reductions and a jackshaft for metal.

You should be able to get the DC motor to run at 1/10th rated
speed if you have good parts. Keep in mind that the TORQUE
available is the same at all the various speeds. Since HP is
speed x torque you have 1/10th the HP at the lowest speed.
Exceeding this means overheating the motor.

Cheers.

Roy wrote:

In the process of making my 3 wheel bandsaw. I am wanting to use a DC
motor of 1 1/2 hp with a speed controller, but would like to add a
jack shaft. as well, just to make sure I can keep up the torque on the
saw at the necessary speeds needed for general metal cutting. The
motor I have is 1 1/2hp Leeson Electric, (removed from a typical
treadmill) and runs up to 5120 rpm and pulls 15 amps. The controller
I have for it is made by Dart and is supposedly capable of handling up
to a 2 HP motor. I understand this controller is supposed to be able
to keep the motors torque up at low speeds, but I would not bet my
life on it. Guess I am just paranoid, as I do not have to much
dealings with DC motors and controllers.

So what ratios would I need to go with to get the saw down to useable
speeds for metal cutting? (Looking for 65 to 550 SFPM from what I
have found out in regards to speed), although it would be nice to
jack it up in speed for wood cutting.

Would I be better off initially reducing the speed with a gear reducer
that drives a jackshaft and then the saw or what? Or should I still be
able to get by with just a 4:1 ration jackshaft and rely on the speed
controller to do its job?

So far except for this problem, the project is going fine. I have one
more wheel (drive wheel) yet to cast and machine, shuld have my tires
next week, have the caster / camber tension assembly made, starting to
work on the blade guides. This brings anopther question to light. Lots
of saws today use simple ball bearing for guides. They seem to last ok
on my H/V bandsaw, but have a habit of allowing lots of crub get by or
get beat into the bearings or blade, so I was thinking on using some
guides similar to what DoAll uses. Is there any materials out there
that I can machine in a home shop thatw ould serve usefull in making
these guides. They need to work with 3/8" at a minimum to no more
than a 3/4" blade. Buying those Cool Cut guides is out of the
question, so I need to come up with a home brew deal. I was also
thinking of using a small engine valve tappet (like found in B & S
engines) that runs in a bushing and is adjustable in and out with a
setscrew. Any other ideas greatly appreciated.

Presently I have just the basic shape of the frame laid out and am
concentrating on making all the actual working parts, so I can juggle
things here and there, and the frame will be built around these last.

Looks like it will have a 17" + - 1" throat size, 8 1/2" to 9" cutting
height, stand 71" tall, have a width of 29" and be 8 1/2" in depth,
take a 107" blade is usiing the three wheels or a 86" blade if
utilizing just two wheels. Table size 20 x 22.

The table is still one item that I need to dio a bit of thinking on. I
wiuld like to be able to mill it out so I can use a push type rip
fence so it looks like a piece of steel plate or perhaps 1/2"
thickness is in order, so if anyone has any other suggestions on a
table they would also be appreciated. I already have a mitre / rip
gauge from a large Delta belt / disk sander that I would like to use.
Visit my website: http://www.frugalmachinist.com
Opinions expressed are those of my wifes,
I had no input whatsoever.
Remove "nospam" from email addy.

Roy, I run a speed of 125 linear FPM on my saw at work and 200 LFPM fixed on
my upright home saw. The work saw has a mechanical variable speed, which I
seldom change except in using it to cut wood. My home saw uses a reduction
gearbox off of a conveyor system with a chain drive to the lower wheel. In
cutting metal, it works perfectly fine. My bandsaw for wood however, runs at
4,300 LFPM fixed. That thing cuts most any wood faster than you can feed it.
Hopefully these figures will be of some sort of help in your planning.

RJ

"Roy" wrote in message
...
In the process of making my 3 wheel bandsaw. I am wanting to use a DC
motor of 1 1/2 hp with a speed controller, but would like to add a
jack shaft. as well, just to make sure I can keep up the torque on the
saw at the necessary speeds needed for general metal cutting. The
motor I have is 1 1/2hp Leeson Electric, (removed from a typical
treadmill) and runs up to 5120 rpm and pulls 15 amps. The controller
I have for it is made by Dart and is supposedly capable of handling up
to a 2 HP motor. I understand this controller is supposed to be able
to keep the motors torque up at low speeds, but I would not bet my
life on it. Guess I am just paranoid, as I do not have to much
dealings with DC motors and controllers.

So what ratios would I need to go with to get the saw down to useable
speeds for metal cutting? (Looking for 65 to 550 SFPM from what I
have found out in regards to speed), although it would be nice to
jack it up in speed for wood cutting.

Would I be better off initially reducing the speed with a gear reducer
that drives a jackshaft and then the saw or what? Or should I still be
able to get by with just a 4:1 ration jackshaft and rely on the speed
controller to do its job?

So far except for this problem, the project is going fine. I have one
more wheel (drive wheel) yet to cast and machine, shuld have my tires
next week, have the caster / camber tension assembly made, starting to
work on the blade guides. This brings anopther question to light. Lots
of saws today use simple ball bearing for guides. They seem to last ok
on my H/V bandsaw, but have a habit of allowing lots of crub get by or
get beat into the bearings or blade, so I was thinking on using some
guides similar to what DoAll uses. Is there any materials out there
that I can machine in a home shop thatw ould serve usefull in making
these guides. They need to work with 3/8" at a minimum to no more
than a 3/4" blade. Buying those Cool Cut guides is out of the
question, so I need to come up with a home brew deal. I was also
thinking of using a small engine valve tappet (like found in B & S
engines) that runs in a bushing and is adjustable in and out with a
setscrew. Any other ideas greatly appreciated.

Presently I have just the basic shape of the frame laid out and am
concentrating on making all the actual working parts, so I can juggle
things here and there, and the frame will be built around these last.

Looks like it will have a 17" + - 1" throat size, 8 1/2" to 9" cutting
height, stand 71" tall, have a width of 29" and be 8 1/2" in depth,
take a 107" blade is usiing the three wheels or a 86" blade if
utilizing just two wheels. Table size 20 x 22.

The table is still one item that I need to dio a bit of thinking on. I
wiuld like to be able to mill it out so I can use a push type rip
fence so it looks like a piece of steel plate or perhaps 1/2"
thickness is in order, so if anyone has any other suggestions on a
table they would also be appreciated. I already have a mitre / rip
gauge from a large Delta belt / disk sander that I would like to use.
Visit my website: http://www.frugalmachinist.com
Opinions expressed are those of my wifes,
I had no input whatsoever.
Remove "nospam" from email addy.

On Wed, 24 Dec 2003 16:13:14 GMT, (Roy) wrote:

===In the process of making my 3 wheel bandsaw. I am wanting to use a DC
===motor of 1 1/2 hp with a speed controller, but would like to add a
snip
I forgot, the wheels are 12 inches in diameter that I cast for this
saw as I could not swing larger and machine them in my lathe.

Regards


Visit my website: http://www.frugalmachinist.com
Opinions expressed are those of my wifes,
I had no input whatsoever.
Remove "nospam" from email addy.

On Wed, 24 Dec 2003 22:36:55 GMT, (Roy) wrote:
On Wed, 24 Dec 2003 16:13:14 GMT, (Roy) wrote:

===In the process of making my 3 wheel bandsaw. I am wanting to use a DC
===motor of 1 1/2 hp with a speed controller, but would like to add a
snip
I forgot, the wheels are 12 inches in diameter that I cast for this
saw as I could not swing larger and machine them in my lathe.

Ok, so the blade will move 3.14 feet for every rotation of the drive
wheel (pi * diameter). With a motor speed of 5120 RPM, that's a
blade speed of 16,077 feet per minute. That's *way* too fast even
for sawing wood.

Typically for wood you'd want a blade speed of about 2000 FPM,
or roughly an 8:1 speed reduction. For cutting steel, you want a
blade speed of about 150-200 FPM, so you need a speed reduction
of about 100 to 1.

Suppose you use a jackshaft and two sets of pulleys, each a 6:1
ratio, which will give a total of 36:1 speed reduction. Then you can
use the electronic speed control to give the remaining 3:1 reduction
for a total of 108:1. That should be reasonable, and still lets you
speed up about 3x for cutting non-ferrous metals.

For cutting wood, you could swap one of the '1' pulleys for a '6'
pulley. That'd give a 6:6 or 1:1 ratio for that set, leaving you with
just the basic 6:1 reduction provided by the other set. The electronic
speed control could then drop the speed the remaining amount to
hit 2,000 FPM for cutting wood.

Gary

I've pondered making a couple of tables with guide slots, but haven't gotten
around to making them yet.

I think the way I'll approach the fabrication is to use 2 thinner plates
(maybe 1/8") on each side of a bar. If the slot wouldn't be deep enough, the
bar could have a slot milled in it.
The plates could be welded to the bar, or attached with flat head
countersunk screws (which could be filled with epoxy to avoid collecting
chips in them).

Some reinforcement ribs could be added where needed. I'll most likely frame
the underside of the tables with bar stock.

WB
..............


The table is still one item that I need to dio a bit of thinking on. I
wiuld like to be able to mill it out so I can use a push type rip
fence so it looks like a piece of steel plate or perhaps 1/2"
thickness is in order, so if anyone has any other suggestions on a
table they would also be appreciated. I already have a mitre / rip
gauge from a large Delta belt / disk sander that I would like to use.

Wild Bill wrote:

I've pondered making a couple of tables with guide slots, but haven't gotten
around to making them yet.

When I went to work on an old wood cutting bandsaw, I started by reading
up on bandsaws. It seems that the bandsaw that cuts dead straight in
the plane of the blade has yet to be invented so instead of a table with
guide slots, I made a flat table and supplied myself with a piece of
angle and two C clamps. A careful test cut allows me to draw a line on
the table in the direction the saw cuts. This changes slowly with use
on a given blade and also changes from blade to blade. The line is
easily erased and re-drawn. My experience with my metal cutting bandsaw
has been similar.

Ted

Yep, I know whatcha mean. The test cut generally reveals which way, how much
to adjust for each time. It's almost funny that blades wander so much. Cuts
made with narrow blades (on sabre saws, for example) seem to be even less
predictable.

My other applications are for slots in tables for grinding operations, where
they'll provide a reference angle.

WB
.....................


"Ted Edwards" wrote in message
...
Wild Bill wrote:

I've pondered making a couple of tables with guide slots, but haven't
gotten
around to making them yet.

When I went to work on an old wood cutting bandsaw, I started by reading
up on bandsaws. It seems that the bandsaw that cuts dead straight in
the plane of the blade has yet to be invented so instead of a table with
guide slots, I made a flat table and supplied myself with a piece of
angle and two C clamps. A careful test cut allows me to draw a line on
the table in the direction the saw cuts. This changes slowly with use
on a given blade and also changes from blade to blade. The line is
easily erased and re-drawn. My experience with my metal cutting bandsaw
has been similar.

Ted