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Hand Taps vs Machine Taps - What's the difference?

Hand Taps vs Machine Taps – Differences?

A brief knowledge drop from our friends over at North America Tool

Hand Tap and Machine Tap are terms that don’t always mean what you think! These are stale industry legacy terms. Originally meant to define a purpose, they can be misleading. They should not define a tap’s modern method of use.

According to some handbooks, the term Hand Tap has traditionally been applied to fractional-size taps having a standard general-purpose length. Most manufacturers don’t limit the description to fractional sizes. Assumed to be straight-flute, these are taps whose flutes are provided as a space to accommodate chips created as the tap cuts. Some research suggests the terminology originated in the early 1800s, when most threading applications were literally done by hand. Yet, when the Machine Age hit its stride after the 1880s, the term Hand Tap was still used for taps that were unchanged in design, and now used on machines, as well as by hand.

As machine tapping is a much faster operation than turning a tap by hand, chip evacuation became more difficult to control. Machine taps would become defined as those with flutes designed with geometry to direct the flow of chips out of the hole. Spiral-point and Spiral-fluted taps fit this category. These alterations in flute geometry improved tap efficiency. Today, with the increasing use of coolant-holes in taps, and external directional coolant-flow, a straight-flute hand tap can offer a similar assist with chip evacuation, and yet it is still perceived by some as different than the machine tap.

Don’t get hung up on a name. Both hand and machine taps sold today are manufactured from the same base materials, and can be used by either method. The decision of which design to use should be influenced by the needs of the job.

P.S. Check out the cool apps North American Tool has to help with tapping and tap design!

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Acme vs Trapezoidal Threads

A brief knowledge drop from our friends over at North America Tool

Acme threads appeared sometime in the late 1800s as an improvement on the square thread form. Square threads were the first choice for motion transfer and heavy loads. But square threads were difficult to produce with available cutter technology. Although the square form was relatively efficient for the purposes required, it was inherently weak at the base of the thread due to the sharp 90-degree angle of the flank. Modifying the included-angle to 29-degrees widened the base of the thread making it stronger. Over time, standards in Acme diameters and pitches were established, all with Imperial Inches in diameter and Threads-per-Inch units of description.

In Europe, similar standards followed using metric units of measure, and the slightly different included flank angle of 30 degrees. Metric standard trapezoidal threads are covered under DIN103. Diameter and pitch descriptions are in metric units of measure.

                            Acme Threads

Acme Threads

                              Trapezoidal Threads

Trapezoidal Threads

Both thread forms serve the purpose of producing linear motion when rotated, usually under heavy load. Some common uses include lead screws for linear actuation on CNC machinery, table lifts, clamps and vises, valve stems, medical diagnostic device drives, trailer jacks and jack-stands. The American Acme form has an included flank angle of 29 degrees. The metric Trapezoidal thread is at 30 degrees. The uses for these thread forms are essentially the same. In fact, taking manufacturing tolerances allowed into consideration, they may be interchangeable when TPI (threads-per-inch) is the same.

The demands placed on the tools that produce these threads are higher due to the amount of material being removed, per tooth, in the process. Controlling chip-load is critical. To design a tap for these threads, North American Tool requires specific detail on the application. Information on the material being tapped, tapping depth, condition of the hole (through or blind), and Class of Fit, is essential to engineer the proper tap. General-purpose taps are available, but are definitely not suitable for every application.

So, what’s the difference between Acme and Trapezoidal? Not much physically. Although the American Acme thread-form is used and accepted throughout the world, the choice of which to use is usually dictated by the origin and user destination of the finished part. To that manufacturer, the difference is everything!

North American Tool is a tier 1 manufacturer of special taps and dies with many taps having a 24-hour lead time. Call us today for a quote.

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Grinding Wheel Productivity

We posed the following question on social media last week and have John Thompson of Pferd to thank for a fantastic answer.

“4-1/2, 5″, or 6″: What is your favorite size grinding and/or cutting wheel? Jumping from 4-1/2 to 5″ is an easy way to get more bang for your buck with your existing grinder but will a 6″ wheel justify the cost of a new grinder?”

We asked John Thompson of Pferd USA to use his technical expertise and many years of experience running abrasives to answer this questions for us. Though John works for Pferd, this information is applicable across all brands and industries. We really appreciate John spending the time to put this information together for us. Without further delay, here is his answer to our question.

Improving Productivity and Performance in Grinding and Cutting

Being competitive in any fabrication process requires a continuing process to improve productivity and reduce labor costs. You may have found the right formula for bending, shearing, welding and material handling to reduce labor and improve process flow to keep the bids low and the work coming in. As these improvements can be very expensive a lot of thought goes into the type of product and overall cost. Long term savings are often the result from a logical investment in the math required to determine the return on any investment and the overall payback time from lower labor and material costs. This is how a fabricator stay competitive and keeps the team invested in the company growth.

But some of this savings can be lost when the productivity of grinding or cutting for preparing material for welding or cosmetically finishing material for paint or powder coating is left up to antiquated equipment or ideas about the difference between Price and Cost when it comes to abrasives. This is NOT a discussion about different grades of Bonded or coated abrasive product. That subject has been beat to death by every abrasive supplier with new grain or new special formulas that promise faster grinding and longer life. This is a discussion with a simple math lesson on improving productivity and reducing overall costs based on the extra life of a slightly larger diameter product.

This is a simple look at the increased performance and reduced costs for applying simple math to improve the volume of material going through the fabrication process and shipped to the customer as a finished product i.e. “Payday.”

There are two false ideas that must be addressed.

One: that the shop worker doesn’t care about getting their part of the job done on time and with minimum effort on their part. They do care as they need that job and the pay it offers to live. The faster they can complete a task with minimal effort means they can move on to the next task and complete the job on time so everyone can be paid and secure that the company is competitive.

Two: Constantly applying pressure to a supplier of consumable product such as abrasives, weld wire, band saw blades and other consumables will make the company competitive even if they do not change the process of grinding prep or finishing procedures. This false idea that high consumption of cheap or small diameter product based on price will offset lost productivity and allow a company to be more competitive. It is the Labor to use the abrasive NOT the Price of the abrasive.

So how can we improve operator productivity and reduce labor costs to keep some of the lost money due to old process issues? Look at the interaction of RPM, Diameter and power tool Weight to work Faster NOT Harder.

Based on Safety Requirements all manufacturers are held to the ANSI specifications or maximum allowed surface feet per minute of 16,000 or 80 meters per second when they make a bonded or coated product for sale in North America. A system of the power tool and consumable product cannot exceed that maximum speed. However the best grinding or cutting is not based on the time to complete a task but how FAST one can compete the task.

Here are several TRUE items about using Bonded or coated product:

One: As long as you do NOT exceed the maximum posted safe operating speed based on the diameter of a bonded or coated abrasive product it is ALWAYS best to run the product as close to the maximum operating speed as allowed.

For example using a 4 ½ inch (115 mm) bonded wheel that is rated at maximum 13,300 rpm (80 M/s) and often used on a properly guarded electric grinder rated up to 12,000 will yield greater stock removal, lighter surface scratch and less overall time in stock removal than any other process.

However, the negative cost is that the ONLY usable working part of a 4 ½ inch (115 mm) is about ½ of the outside diameter of the wheel. Then the power tool actually keeps the operator from using the rest of the wheel.

If the operator used a 5 inch diameter bonded wheel that is rated at 12,200 rpm (80 M/s) on the same properly guarded electric grinder rated at 12,000 rpm the overall speed of the outside of the wheel is 430 surface feet per minute faster. Faster diameter speed means faster grinding and cutting and the job gets done faster with less effort.

BUT Speed is NOT the whole story let’s look at effective life of the product based on Diameter only.

A 4 ½ (115 mm) inch diameter bonded product (on today’s power tool) has an effective life of ½ inch diameter and is often discarded when the product gets to 4 inches overall due to the size of the head of the grinder.

A 5 (125 mm) inch diameter bonded product (on today’s power tool) Has an effective life of 1 inch diameter when discarded at the 4 inch diameter based on the same physical size of the head of the power tool. Actually there is 44% MORE life on a 5 inch diameter wheel than a 4 ½ inch. With the increased surface feet per minute speed (32% FASTER at the outer edge with the same overall wear life) is really a better way to save money by buying less and getting more productivity from less wheel.

The REAL Savings is going to the 6 inch system. The Safe operating speed on a 6 inch diameter bonded product is based on the 80 M/s rule and is listed at 10,200 rpm maximum. However with a grinder that is offered in the same physical size as the 4 ½ and 5 inch versions but rated at 10,000 rpm to stay in safety guidelines offers the BEST performance at the lowest cost. The surface speed of the 10,000 rpm 6 inch example against the 5 inch 12,000 example is EXACTLY the SAME (15,708 Surface feet per Minute). The real saving is in the life of the product. The difference in total life of the 5 inch to the 6 inch diameter consumable is 62% MORE wheel. The difference in total life between the 4 ½ and the 6 inch consumable is 133%!!

Overall the cost of the new 6 inch power tool required to use the 6 inch product safely is easily justified due to the performance and life of the product. If the fabricator changes their fleet of older grinders from 4 ½ to 6 inch the return on the overall investment is less than 1 year. This is one of the BEST ways to improve performance and lower the Overall cost of a necessary process in the shop to really keep the product going out the door.

It is just looking at the process using simple math.

John Thompson