Although fabricators often use abrasive wheels for cutoff, have you considered the benefits of reciprocating saw blades? “Recips” are excellent for cutting applications because of benefits such as safety through reduced vibration and noise, a drastic reduction in spark production and fire risk, ease of access to the work, large cut capacity and multi-purpose ability. With a push-pull motion, reciprocating blades can cut through metal quickly and cleanly. Bi-metal reciprocating blades will cut through everything from the thinnest sheet steel up to heavy duty steel sections. 

There are a range of important benefits that recip blades offer. So, before you pick up your grinder and mount that abrasive wheel, consider the following:

Safety -

Due to the way reciprocating saw blades work in materials and the milling process, there are virtually no spark projectiles which can cause operator injury and property damage via fire or explosion. With recips, metal is machined away in chips from the material with each pass. The energy created from the recip cutting process is very limited, so in turn, heat is extremely reduced. The temperature is kept very low across the substrate and the cutting tool. This keeps high temperatures from building in the chips and reduces liabilities. Another advantage is that no “hot permit” is required when using recip blades, which saves on costs.

One the other hand, cutoff abrasive wheels rated to 80 m/s may spin up to 16,000 sfpm, and throw 1,800° sparks as far as 30' from the grinder. These actions put abrasive and metallic dust into the air, which can be inhaled. The liquid hot metallic sparks are not only dangerous to the operator, they can be a fire hazard. Also, depending on the substrate, the sparks can cause chemical reactions with the metals being worked, encouraging development of iron oxide (red rust) on various materials. Guards are required on a grinder, and if ignored and misused, users are subject to significant fines. For all these reasons, abrasives receive new safety regulations nearly every year.

Particulate Size -

Recips produce larger chips and have virtually no wear. This means that the dust emissions are extremely limited, resulting in cleaner finished cuts and healthier air for breathing (another safety advantage). Cleanup is easier since the swarf is contained and distributed from the tooth gullets and deposited to the floor in one place, instead of becoming airborne dust that cutoff wheels produce.

With cutoff wheels, abrasives and metallic dust are generally very small, especially with fine grits. This results in a lower mass with particulates that can get hung up in the atmosphere more easily with a higher chance of being inhaled.

Cutting Tool Endurance  - 

Industrial grade recips, such as Starrett 3X Power Reciprocating Saw Blades, utilize premium quality materials that can endure a tremendous amount of torsion and still be used effectively with a very limited risk of breakage. This keeps the operator and those in the surrounding area much safer, reducing potential liabilities. In contrast, it is not uncommon for cutoff wheels that run at higher speeds to shatter, producing dangerous flying shrapnel.

Superior Reach -

If an application requires significant reach, recips are a good cutting solution. Since there are no guards on reciprocating saws, the blades can reach as far as a foot away from the end of the saw, getting into tight areas with precision and a remarkable degree of safety to the operator and those in the vicinity.

If using a cutoff wheel, it might be tempting to remove the guard in order to reach a particular area. However, it only takes a fraction of a second for a wheel to break and the results can be catastrophic putting the operator and those in the area at high risk, as well as putting the company at a high risk of liability.

Recips offer a versatile cutting solution that reduces changeover for substrate geometry differences, and offers better reach with a lighter tool. For example, a 9” grinder is required to cut a 3” pipe, but the recip saw size remains the same no matter the length of blade and the  user can make the cut with a 6" blade.

Economics –

The right type of recip blade with an enhanced tooth design such as the Starrett 3X Power Bi-Metal Blade cut more efficiently, enabling users to make up to three times the number of cuts than conventional recip blades, and are engineered for use on corded and cordless saws.

In terms of wear, reciprocating saw blades hold a constant size and therefore, a constant sfpm so the cutting efficiency is very similar from the first and last cuts to be made with the saw.

A versatile solution which has the ability to cut aluminum, solid and non-solid profiles and stainless steel, 3X Recips blades will yield the best performance results in tube and pipe cutting applications as well as thin gage materials. This is where a user will find the greatest savings in cost per cut.

Note that an abrasive cutoff wheel benefits from high sfpm because the increased speed allows for faster impacting of the abrasive grains. However, the grinder does not increase in rpm as the abrasives’ diameter wears down, resulting in a constant decrease to the sfpm speeds of the wheel. So, there is a negative correlation between wheel diameter and seconds per cut. As one decreases from the start of use, so does the other.

See Chart 1 (below) - Performance cutting tests conducted at Starrett comparing 6" 3X Recip blades to 4.5" abrasive cutoff wheels yielded an average annual savings advantage of over $14,000 when making 74,750 cuts in schedule 40 steel pipe, as compared with using a variety of cutoff wheels for the same application. This example is based on what a small or mid-sized shop may see and assumes 3 operators at the national average labor rate* using 1 box of abrasives (25 wheels in each box) per week each for a total of 75 wheels weekly versus 6 recips per operator each week totaling 18 blades for the same weekly time period.

Operator Experience –

Importantly, for the operator experience, recip blades offer good ergonomics and convenience. For example, due to being able to cut faster, less time is spent operating the saw and experiencing vibratory forces. Particulate emissions are minimized and the recips have on average a 15dB quieter operation. In addition, fewer blade change-outs are required compared to wheels, which results in significant time savings.

Ease of Selection -

Reciprocating blades such as Starrett offer color coding on the universal shanks: for example, blue for metal cutting, red for multi-use, yellow for wood cutting, as well as black for heavy duty multi-use enable a fast, easy way to judge what blade to use for the application.

Typically, two different reciprocating blade shapes are offered:

• ‘parallel’ for harder cuts, especially when the tip needs to be forced
• ‘tapered’ for straighter cuts, which has a better possibility for getting to hard to reach places and offers straight cuts

The number of teeth per inch (TPI) usually determines what type of material a recip blade can cut. Typically, a higher number of TPI slows the cut, but offers a cleaner finish and is also ideal for thinner metal cutting applications.