Band saw cut speed on 2-1/2" stainless solid

kb0thn · Jun 18, 2018

Hi Guys,

I have a WF Wells horizontal band saw. I use it primarily for cutting round solid 304 SS and 6061 into slugs for chucking in my CNC lathe. Typical part is in the 2 to 2-1/2 diameter.

My cut speed is SLOW. Cutting through 2-1/2" 304 SS today and it is taking about 30 minutes per cut. This is with a 3/4" x 0.035" 4/6 tooth variable pitch Lenox QXP bi-metal blade. According to the dial on the saw, my blade speed is about 80 feet per minute. I am using a "Nonstaining Sawing Coolant" from McMaster-Carr:
McMaster-Carr

If the blade was brand new the cut might be 20 or 25 minutes. So not much better when new.

Assuming this cut speed is low, what can I do to improve it? Saw seems to be setup for 3/4" blades and WF Wells says that it isn't optimal to switch it to 1". I don't need 1 minute cut times, but something closer to 10 minutes per slug would be nice.

Thanks,

-Jim

CalG · Jun 18, 2018

Pressure?

You would think each blade tooth would carry a good chip. Even at .0005 per tooth as it passes through the work would better your present rate.

What are you doing to limit penetration?

kb0thn · Jun 18, 2018

CalG said:
What are you doing to limit penetration?

I am not sure I am following. In terms of down feed pressure, I have the valve fully open. So it's the weight of the saw head for pressure.

Thanks

sfriedberg · Jun 18, 2018

I agree that's very slow. And your "new blade" speeds are also slow. You are not making the typical mistake of using a blade with too many teeth, so that's not the problem.

I don't have any better idea than to repeat CalG's question about feed pressure. Does that thing (never run a Wells, myself) have a counterbalance or spring that can be adjusted for more pressure? [Added in edit: and, you just responded to that question.]

Limy Sami · Jun 18, 2018

Lotsa Lenox info here file:///C:/Users/Mark%20Figes/AppData/Local/Packages/Microsoft.MicrosoftEdge_8wekyb3d8bbwe/TempState/Downloads/LENOX%20Guide%20to%20Band%20Sawing%20(1).pdf

FWIW a quick look said your blade speed is a bit low,

As to sawing pressure - cheat and hang a weight on the end of the saw frame

kb0thn · Jun 18, 2018

Limy Sami said:
FWIW a quick look said your blade speed is a bit low,

Good catch. I bumped it up to ~115 SFPM. Now cut time is right around 20 minutes. That's a good improvement. I don't do much sawing, so I had 75 SFPM stuck in my head. Must have been from the 17-4 I was doing last.

Neighbors shop with a Marvel automatic saw says this would be 5 minutes or less on their saw.

Limy Sami said:
As to sawing pressure - cheat and hang a weight on the end of the saw frame

It's a dual post setup. But there is some room on top to stack some stuff. And I have about 300 pounds of aluminum blanks sitting on a pallet next to the saw. I will try that.

Thanks!

sfriedberg · Jun 18, 2018

kb0thn said:
Neighbors shop with a Marvel automatic saw says this would be 5 minutes or less on their saw.

I'm guesstimating my Ellis 1600 would take about that time, using a 4/6 TPI blade similar to yours.

adama · Jun 18, 2018

Pressure is easiest to judge based on the swarf. On a solid that size it should matt together have some length to each piece, if its fine and powdery you need more weight, i often use to use a 6" G clamp on a similar saw i use to use at a customers, though on that saw does it also have a spring counterbalance? If so you need to add more pressure there.

Its worth adding with band-saws theres a kinda sweet spot, a given tooth will only cut so many times through a given material and its all about maximizing that by feeding as much as you can with out catastrophic blade damage.

Equally you should be aiming to set the hydrulics such that the blade advances at a near constant rate through the cut, this is really important on break through - exit of the cut as thats generally were blade damage happens or at the start.

Taller blades are always better, but assuming you have the guides as near to the work as possible ( i would move it a lot closer than your pic) 3" dia and under is easy enough to do with a 3/4" blade.

Limy Sami · Jun 18, 2018

kb0thn said:
It's a dual post setup. But there is some room on top to stack some stuff. And I have about 300 pounds of aluminum blanks sitting on a pallet next to the saw. I will try that.

Thanks!

Do it in small increments …...I'd start with a couple of lbs

Red James · Jun 18, 2018

If you have several of these 304 blanks required, order them cut to length from your stainless supplier. Some suppliers charge real money to saw cut, but certainly not all. Check with a few steel suppliers for quotes on cut-to-length and find a reasonal cost . . . your are spending $30 per cut now, and that is not reasonable.

kb0thn · Jun 18, 2018

adama said:
Pressure is easiest to judge based on the swarf. On a solid that size it should matt together have some length to each piece, if its fine and powdery you need more weight, i often use to use a 6" G clamp on a similar saw i use to use at a customers, though on that saw does it also have a spring counterbalance? If so you need to add more pressure there.

Chips look pretty good.

No counter balance or anything. It's just dual posts with hydraulics to raise the saw. Then there is a needle valve that controls how fast it comes down. I have the valve wide open.

adama said:
Equally you should be aiming to set the hydrulics such that the blade advances at a near constant rate through the cut, this is really important on break through - exit of the cut as thats generally were blade damage happens or at the start.

Break through at the end has always been fine. No drama. You really don't even hear the cut finishing.

adama said:
Taller blades are always better, but assuming you have the guides as near to the work as possible ( i would move it a lot closer than your pic) 3" dia and under is easy enough to do with a 3/4" blade.

When I first got the saw I set the guides to be right up to the work. But it turns out that the guide hits on the outfeed table and the saw never finishes the cut. If moving the guide in is likely to help speed things up, I'll cut modify the outfeed table or guide to let it get in closer.

Thanks for your help!

kb0thn · Jun 18, 2018

Red James said:
If you have several of these 304 blanks required, order them cut to length from your stainless supplier. Some suppliers charge real money to saw cut, but certainly not all. Check with a few steel suppliers for quotes on cut-to-length and find a reasonal cost . . . your are spending $30 per cut now, and that is not reasonable.

It's for our own product. We have a handful of different size bars (1", 2-1/4", 2-1/2" are the most common) that we make most of our turned products from. And it's all pretty much order driven, so we aren't doing too much inventory. So I can't reasonably get precut blanks ... unfortunately. Usually with the cycle times on the lathe, the slow cutting time isn't a problem. But in this case my first op is in the mill so now I have a mill tied up for a day even though its spindle is only turning for 30 minutes.

My SS supplier, Liebovich, gets us bars within a few days. Cutting turns into either no-quote or they spend a week and a half getting us blanks.

But I appreciate the suggestion. I do agree that the saw cutting is too expensive. I can bang these out on my dry cut saw in about a minute. But the blade is $100+ and often it only lasts a dozen cuts before it loses a tooth and it's game over.

Thanks

kb0thn · Jun 18, 2018

So upon reading the manual for the newest version of this saw, I think I see a potential culprit. There is a metering valve that controls the cutting force. It is in the hydraulic circuit with the drop valve on the control panel. My guess is this valve or linkage is not working properly and limiting the down force. Stacking 144 lbs of aluminum blanks on top of the saw head didn't change the cut speed.

Tomorrow should be fun.

garyhlucas · Jun 18, 2018

I'd definitely try to get the blade supports closer to the piece. I think I would also try a coarser blade. At average of 5 teeth per inch you have 12 teeth cutting at the same time and if you don't have the down force to keep the teeth cutting then your cutting speed will be lower and your blade life as well. Increasing the weight on the blade may cause it to buckle, especially with the guides so far apart. Getting more pressure per tooth by reducing the number of teeth in the cut might work wonders. Your chips are fairly short and straight. I'd like to see them curled up as each tooth took a cut all the way across and rolled it up in the gullet.

Throw a clamp on amp meter on the motor too. If you aren't seeing full nameplate horsepower during the cut then you still have the power to cut faster.

adama · Jun 19, 2018

kb0thn said:
Chips look pretty good.

View attachment 231032

Yeah thats not the kinda swarf you expect to see of a circa 2" bar cut that takes 30 minutes. That even in that pic looks about right.

Might be worth just verifying blade speed out of the cut, knowing band length, a simple pain marker blob bellow the blade guides and counting how many times it comes around might be in order to at least prove your blade speed is in the approx ball park. Some vari speed drives can wear a long long way out of indicated speeds, most have adjustment though to correct this.

You can prove out the hydraulic down feed by taking a cut with out material in the vise, should be a lot lot faster, most saws fully open fall scary fast, more than fast enough to need a new blade any how!

How old is the blade, because cutting stainless once they do start to dull cut time goes through the roof, yet aluminum or such would happily cut at much the same pace.

Other possibility is the saw is jamming on the columbs with the side cutting thrust, have only been around a twin coloumb amada and that was a think of beuty compared to what you have there, that said again you would expect to see it in the cut.

Sami's comments about aditional weight is spot on, should only need a few extra pounds tops normally.

The amada twin coloumb saw i was around also fell fast till it nearly contacted the work then dropped to feed rate as it were, is yours setup like that and are you by any chance not changing over to cutting pressure correctly?

Limy Sami · Jun 19, 2018

Stupid thought time.

Have you checked your watch?

DDoug · Jun 19, 2018

kb0thn said:
So upon reading the manual for the newest version of this saw, I think I see a potential culprit. There is a metering valve that controls the cutting force. It is in the hydraulic circuit with the drop valve on the control panel. My guess is this valve or linkage is not working properly and limiting the down force. Stacking 144 lbs of aluminum blanks on top of the saw head didn't change the cut speed.

Tomorrow should be fun.

Fix this problem.

Your rubbing the blade, and not cutting.

Work hardening may be a problem here.

Richard King · Jun 19, 2018

I see your in MN, Give Tom a call he is in Brooklyn Center and knows his stuff! Band saws and grinding supplies.
We feature SAIT products.

CalG · Jun 19, 2018

kb0thn said:
So upon reading the manual for the newest version of this saw, I think I see a potential culprit. There is a metering valve that controls the cutting force. It is in the hydraulic circuit with the drop valve on the control panel. My guess is this valve or linkage is not working properly and limiting the down force. Stacking 144 lbs of aluminum blanks on top of the saw head didn't change the cut speed.

Tomorrow should be fun.

I was going to ask how long your saw took to cut air.

kb0thn · Jun 19, 2018

I had one of my guys adjust the metering circuit. There is a hydraulic sensor of sorts that measures how far the blade deflects and adjust the speed which the saw descends. I think the concept is that the saw can drop scary fast until it gets to the work piece, then the drop speed is controlled by the metering valve on the control panel and this extra thingy. With adjusting this piece alone the cut time has been reduced to 8 minutes.

We also trimmed some extra guarding off and now we can get the blade guide much closer to the work. With that change, I'm told that it is now about 3.5 minutes per cut!

With PM's help and paying one of my techs to fiddle with it for 3.5 hours, I've got an 8.5x reduction in cut time...! Big smile on my face.

Thanks for the help everyone!

Band saw cut speed on 2-1/2" stainless solid

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