Bandspeed Speed Pros/Cons?

[Thomas Utley]

My search terms yielded no usable answers, so apologies if this has been asked and answered previously.

I'm evaluating a larger (36") bandsaw acquisition. This manufacturer offered several direct drive motor RPM options in 300-RPM increments. From what I have read, 5hp appears to be a constant regardless of RPM rating. The different speeds are determined by motor pole count.

What are the pros and cons of low vs. high wheel speeds, and corresponding SFPM blade speeds, on a big saw like this?

I do want plenty of torque for deep resaw capability, but I won't use it for that every day.

Thanks,

Tom

[David Kumm]

Most direct drive 36" saws run 600-720 rpm ( 8 pole ) motor. The FLA for 5 hp will be about 19 @ 240 three phase so the torque is quite high compared to a normal 4 pole motor. That equates to about 6500 SFPM and is about as low as the DD options will go. There are some 900 rpm motors on 36" saws ( Tanny did that more often ) but that is more normal for a 30" saw to get the same blade speed. I would not go faster for wood as belt drive saws are usually in the 4500 sfpm range. It takes a well balanced machine to run at the higher rates. Dave

[Van Huskey]

If we first make the assumption that the machine is balanced enough to run (relatively) vibration free at the wheel speed it is set up for then speed is your friend when resawing.

Many of the large DD bandsaws have a much faster blade speed than the belt drive machines which usually top out in the 5,000 fpm range. You will occasionally see 36" and larger DD bandsaws top out in the 8K to 9K range which is an experience just to near. The big pro of higher speeds is faster chip clearance which is important in tall resaws particularly when they are being power fed. If you plan on hand feeding 4000-5000 is plenty but the extra won't hurt. There really isn't a lot of down side to high blade speed (on a balanced saw), there are some theoretical ones but not likely to ever manifest themselves in a real way.

I assume you are looking at used saws if so don't look past a good saw at a good deal even if the speed is in the higher range. If you are looking at new ($$$$$) then contact the band manufacturer for the bands you want to run and get them to give you the optimum speed range for the blade, material, height of cut and feedrates you plan to use.

If you are a hobby or small commercial user then don't overthink it, buy the saw in the best shape in your price range.

[Thomas Utley]

This is great input, appreciate it.

The saw I'm looking at currently is a Moak 36. I don't yet know the motor RPM, but the seller says it's 5hp direct drive. I will address wheel balance if/when I decide it's the right saw for me.

It's for non-production use, so this alleviates any concerns I had on speed.

Thanks!

Tom

[Darcy Warner]

Moak offered 600rpm, 720, 900 and 1200.

Sfm of 5420, 6500, 8150, 10,855.

Those machines would have Carter wheels.


I have 3 36" saws, one at 600, one at 690 an another at 870.

I like the faster one.

[Thomas Utley]

A blade singing at nearly 11K SFPM would be something to see/hear. Wow.

Thanks so much for the info.

Tom

[David Kumm]

Pay attention to condition of the Carter Wheels. Expensive to repair. Bobby at Woodworkers Toolworks will redo the rubber if needed. There are many fans of Moak but they are not as high on the used market as the Oliver, Tanny or Yates. Condition is always key. Dave

[Thomas Utley]

Any idea what it might cost for a full re-tire on a set of Carter wheels? I seem to recall the Carter design is split, making installing new rubber easier.

Am I remembering that correctly?

Thanks,

Tom

[Darcy Warner]

Set of 36" Carter tires are around 600 bucks. I can change Carter tires in 45 minutes, glue on tires take a couple days.

There are other options for tires as well.

[Bill Dufour]

Blade speed is important for metal saws but not so much for wood. Some metal saws go to below 50 feet per minute. I think that speed is for band files not really sawing.
Bill D.
I tried to find a video of a band file but all I found were sandpaper machines.

[Al Launier]

Perhaps I missed it, but what will you be cutting with the BS? As Bill said above speed is much more critical when cutting steel, not so much for aluminum.

[Thomas Utley]

Ouch, that's expensive. Good info to have prior to negotiating a price on a saw with Carter wheels. Thanks!

[Thomas Utley]

Perhaps I missed it, but what will you be cutting with the BS? As Bill said above speed is much more critical when cutting steel, not so much for aluminum.

It's intended to be my primary woodworking bandsaw, especially for resawing my own veneers.

I'd be more inclined to get a DoAll or similar heavy duty bandsaw with blade guides designed for the forces required to cut steel.

[Thomas Utley]

Blade speed is important for metal saws but not so much for wood. Some metal saws go to below 50 feet per minute. I think that speed is for band files not really sawing.
Bill D.
I tried to find a video of a band file but all I found were sandpaper machines.

Band files are as crazy to watch as you'd think. I'm not sure there's much call for them anymore after the advent of belt grinders using the right abrasive. You can likely buy multiple 2x72 BGs for the cost of a file set.

[Peter Christensen]

I believe if the motor is a 220/240 Delta wound three phase you could use a VFD to adjust the speed of the motor, up or down as needed, limited by the motor's ability to cool. Worth looking into.

[Thomas Utley]

I believe if the motor is a 220/240 Delta wound three phase you could use a VFD to adjust the speed of the motor, up or down as needed, limited by the motor's ability to cool. Worth looking into.

Agreed. I'm using VFDs on two machines at home already, a 16" South Bend metal lathe (3hp) and a Baldor pedestal buffer (1.5hp). A 5hp (~4kW) VFD won't be cheap, but variable speed would be a nice feature for sure. Overclocking older motors which aren't "VFD rated" isn't something a motor manufacturer would ever recommend, but there are countless examples of people doing exactly that in short spurts with no noticeable impact to the motor's life. BTW, the same thing applies to underclocking...for motors relying on shaft-mounted fans for cooling, running too slow is worse than running too fast.

[Peter Christensen]

Thomas I got my VFD directly from Powtran in China for my CV-Max (5hp) and to my door it was less than half the price of those Carter tires. $170US plus about $70 for the shipping. I do envy you getting that big saw. It would drop through my shop floor into the garage below.

[Darcy Warner]

Ouch, that's expensive. Good info to have prior to negotiating a price on a saw with Carter wheels. Thanks!

Not really, saves time and labor.

[David Kumm]

Keep in mind if running a direct drive on a vfd that it is all ready likely 600 or 720 rpm so not much point in slowing it much. The low rpm motor will have a much higher amp draw- as i said earlier, more like 19 amps rather than the typical 13 so the vfd needs to be closer to a 7.5 hp equivelant to have an output amperage of 20. In addition to the rubber, the Carter wheels themselves need to be run to ensure they don't have problems as they are also expensive to replace. Many old saws will run an aluminum top wheel and cast iron bottom, either spoked or full. You can go to owwm.org and read up on posts for old saws including Moak. Dave