Help! My Saw Won't Cut Straight!

By Brian Thornton

I want to focus on a few of the ways you can make sure your high-production cold saw like the Nishijimax will cut straight even on your tight tolerance jobs. New and old customers alike will often call the office confused or upset by the fact that suddenly, their high-production cold saw is not performing like it used to. “I think we got a bad bunch of blades” they will often say. I won’t comment on the blades my competition sells, but Kanefusa blades have some of the highest quality control standards in the industry. One of the best things about working with Kanefusa is I know with a high degree of certainty that when you have a problem, it’s not the blade’s fault.

If there is a “blade problem”, it is most often fixed by supplying the correct blade for your application. We might have to change the number of teeth to make sure your teeth in the cut (Zi) are appropriate for your application. We might have to switch you to a coated carbide, or a tooth form optimized for stainless steel so you can get through that really tough material you just got in. These are all questions we can discuss when you call looking for our expertise, and why we work so closely with our customers and dealers during the discovery process. At Pat Mooney Saws, we create value by providing the right sawing solution for your application the first time. We get there by collecting all the useful information we can from our customers or dealers and leveraging our experience and knowledge.

You’re probably thinking “Of course the salesman isn’t going to blame his product for the problems I’m having,” and that’s fair – pushy salesmen are the best at defending a product that isn’t working right. However, I’m not that kind of salesman.

So, what should you do then when your high-production cold saw isn’t cutting straight? Follow these easy steps to keep your cold saw in the best working order.

1 – Look closely at your material.

There is no such thing as a straight bar. Like any other product, there is a tolerance that a mill will allow when they are making a bar, pipe, or tube. The larger the diameter the more likely it is there will be bends in the material. If you observe a bend in your material, it doesn’t mean you can’t cut it – it just means it won’t be square. Often people will mistake a temporary bend in the material as evidence a blade has begun to fail. Most of the time, this isn’t the case.

2 – Keep the saw clean.

Before I begin let me be clear, “clean” is a relative term when we’re in the manufacturing world. Over time, your saw accrues the patina of a machine that has been well-used. This does not mean that you can treat it like a beater car with 200k miles on it. One of the first lessons I learned working in the sawing world is that a Nishijimax is a precision machine, and in order for it to operate precisely it must be cleaned. If your machine is cutting out of the square, assess the cleanliness of your key contact areas.

  • Blade housing and blade guides: The Nishijimax uses 6 blade guide pads that when shimmed properly sit 0.002” away from the blade. Every time you change a blade these areas should be wiped down, and any material build-up should be removed. Think of it this way, if your front door won’t close all the way, you inevitably will get a draft during the winter. Cleaning the blade guides and saw housing with each blade change will ensure the door closes properly so nothing from “outside” can get in. Otherwise, your blade will cut out of square, and you simultaneously lower your tooling life and potentially damage a critical cutting area.
  • Clamps and cutting area: While you’re wiping down the blade guides you should also wipe down the area of the saw bed – the area that clamps the material before it cuts. Your clamp pads will wear over time and need to be replaced, so this is also a good time to check that out as well. When cleaning, you should not use a corrosive cleaner. If you do it consistently, you should only need a rag and a little mineral water to help it along. If you have material caked onto this critical area, give our office a call and we can advise you on proper procedures. This is critical if you have a very tight tolerance. For example, let’s say you want to hold a tolerance of 0.005”. If you’re taking a chip load of 0.08 mm/t and chips build up in the clamping area, you will not get good parts even though the saw is capable of holding this.
  • Bird’s Nest: Sometimes chip buildup can occur underneath the saw bed, which we call a bird's nest. While you’re wiping down the blade guides and saw bed, you can use a piece of banding or another slim piece of metal to check if there are any chips inside the cutting slot that the blade goes through. Remember, those chips are pieces of metal that are not clamped down properly. You will lower your blade life if you don’t check for a Bird’s nest buildup.

If the two above steps are not part of your operator training, you are doing your customers a disservice. They expect you to send them good billets or finished parts, without checking everything above you will have quality issues that will inhibit your productivity (and potentially ruin your saw!) Lastly, your maintenance department should check these with some regularity.

3 - Check the alignment.

As one of our technicians at Pat Mooney reminded me recently, there is a difference between the saw being level and the saw being aligned. When we install a Nishijimax machine, we do not bolt it to the floor. That way, in the event of a catastrophic blade failure, wrong parameter inputs, or incorrect material handling, the spindle motor will not be permanently damaged. This also means that if your machines are on the ground and you fill tubs with your billets, a forklift operator can over time (or all at once) knock the saw out of alignment with one of our custom load tables.

You can use a laser level like this one to help you align your machine, or schedule yearly PMs with us and we’ll make sure everything is taken care of.

I recently had a customer who was holding a tolerance of 0.002” on most of their parts, seemingly overnight it jumped to 0.010”! Their customer was upset, and they didn’t know what to do so they called me. When I showed up to help, I immediately noticed material buildup on their blade guides and confirmed that their saw had been knocked out of alignment. A little bit of elbow grease, operator training, and a couple of bumps to put the saw back in alignment meant their squareness went back to 0.002”. Going forward, I know they’ll pay closer attention, and if you have a cold saw in your facility and pay attention to the three above points, you’ll increase your tool life and decrease your service visits and quality issues.


About the Author

Brian Thornton is a professional saw blade expert at Pat Mooney Saws. As an Account Manager, he specializes in metal cutting and finding the best sawing solutions for his clients.