A Brief History of GMP

In 1936, a young engineer with an entrepreneurial spirit began a specialty machine shop in Philadelphia. Among his early clients was the Pitcairn Autogiro Company in Willow Grove. This young engineer was none other than George M. Pfundt, founder of General Machine Products, pictured here in Washington DC alongside the flying machine (AC-35 Autogyro) that used his precision machined parts.


However, it was the local Bell Telephone Company of Pennsylvania who approached GMP to make components for their line construction work. This partnership would prove to be the future destiny for the fledgling engineering and manufacturing company. Following his early success with Bell of PA. George Pfundt began offering his specialty services to other utility companies, notably Philadelphia Electric Co. On the recommendation of a Bell of PA buyer, George was introduced to buyers at the Western Electric Company, and so began GMP’s eventual specialization in the utility construction field.

Soon GMP expanded their production shop providing space to begin manufacturing telecom industry equipment and components. At the same time, they were producing equipment for a vast number of clients, doing contract manufacturing of new developments for the war effort, most notably the Link Trainer, an early flight simulator for the US Army Air Corps and Navy.

George’s close relationship with Bell Telephone Laboratories in Murray Hill, N.J. led him to begin designing and manufacturing experimental prototypes for new products that could be used within the Bell System.

In the 1940’s, GMP’s relationship with the Bell Telephone Company was flourishing. In collaboration with engineers from the Bell Labs, GMP pioneered the modern cable lashing machine—a true innovation— to bind telephone cables with the messenger wire in the placing of aerial cable.

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The invention was groundbreaking, subsequently establishing General Machine Products as the telephone industry standard in cable lashing technology. Since the cable lasher’s inception, GMP has produced, sold, and repaired over 30,000 lashing machines.

By 1956, business was booming; telephone lines stretched from coast to coast and the first ever Trans-Atlantic submarine telephone cable had just been laid by AT&T, the parent company of the Bell System. Having outgrown the original factory building, GMP found a new home in Trevose, PA (a Philadelphia suburb), and built a 100,000 square foot manufacturing plant. By 1957 in their new factory at this point, GMP was producing over 500 telephone line construction tools, many of which are still in use today.

Telephone Poles

GMP continues to operate out of Trevose, PA, and is led by George M. Pfundt’s grandson, William. GMP is recognized as a premier worldwide supplier of specialty tools and equipment for the telecom marketplace. The company’s 800+ products are known for their robust design and durability, capable of withstanding years of frequent use by professionals who know them as the “tools of the trade.”

Visit www.gmptools.com learn more about the equipment trusted by thousands of telecom technicians every day!

Proper Use of the Apollo Cable Lasher


Here at GMP Tools, we offer a variety of different cable lashing machines. Each lasher has specific features and unique modifications that provide today’s telecom installers the best possible equipment to complete any cable lashing job effectively and efficiently. Our cable lashers include:


We’ve already shown you the difference between the J2 and J2B cable lashers. Today, we’re taking a closer look at our newest addition to the cable lasher family: The Apollo.


What makes the Apollo different, you may ask? For starters, this is not just any spinner; it’s a GMP lasher! No other lasher or cable spinner can deliver such high-quality results with as little effort.

The entire list of Apollo features and benefits can be found on our website, here.

Proper loading and lashing technique as well as regular maintenance are crucial to keeping your Apollo spinning at full force. We want every technician to be getting the most out of their Apollo, so in this blog we’re going to show you exactly how to load, use, and maintain your Apollo Cable Lasher.


Loading the Apollo Cable lasher correctly is crucial for an effective and durable lashing procedure. This video will show you step by step how to load cable into the lasher.

Follow the same loading procedure on the opposite side of the lasher for the second coil.  


  1. Check the lashing wire coils to ensure there is enough lashing wire for the span.
  1. Lower the rear gate to its lowest position by fully depressing the thumb latch and sliding the roller down. Ensure that the rear gate is open and the drum is locked in position.
  1. Open both the front and rear strand locks by pulling up on the release knob.

There should be an audible “click” when the strand locks travel from the locked position to the open position. The strand locks aren’t used in the over-lashing procedure and should remain in the open position.

  1. Open the front gate by actuating the release lever towards the front of the lashing machine. The roller on the front gate should pivot 180 degrees and out of the way.
  1. Attach a hand-line to the lasher handle and raise the lasher to the strand.
  1. Attach one of the snap hooks on the lasher bridle to one of the towing eyes.

Attach the other snap hook around the strand and existing cables to serve as a tether.

  1. Place the lasher on the strand and ensure that the strand is centered in the grooves of both of the front and rear rollers.
  1. Using the proper cable raising procedure for your application, lift up to the strand the cable or cables you want to lash, close the front gate and let the cable(s) rest on the horizontal roller.
  1. Raise the rear cable lifter by pushing up on the bottom of the lifter that contacts the D shaft. The thumb-latch doesn’t have to be activated to raise the cable lifter.
  1. Adjust the position of the vertical rollers so that they barely touch the sides of the cable(s). This will have to be done as the bundle size changes.
  1. Now the final steps. Pull up on the handle to de-clutch and disengage the drive wheel to pull some lashing wire from the lasher. Secure the lashing wire to the strand by using a GMP ‘D’ or ‘E’ lashing wire clamp.

Attach the bridle assembly to the towing eyes on the Apollo lasher, and you are ready to lash.

If you need help setting up your Apollo lasher, we can be reached at our technical support hotline: +1 215-357-5500

Each Apollo lasher also includes a 6 ft. (2 m) towing bridle and a rugged, weather-tight storage chest to securely protect your lasher investment while it’s not in use.

The Apollo and every GMP lasher is fully serviceable to “good-as-new” specifications at our factory and at factory-trained service locations around the globe.

Microduct Overriding: Part 2

In our first installment, we introduced the microduct override process of installing a new microduct in an innerduct occupied with an existing fiber optic cable. A single microduct or multiple microducts can be placed at one time during an override operation. We also outlined the major pieces of equipment required in an override including the Junction Box. In this installment, we’ll discuss the Junction Box and the other microduct blowing accessories required for a microduct override operation.

jboxThe junction box or “J” box (pictured above) provides the insertion point for the new microducts into the existing occupied pathway. The precision machined aluminum base and lid form a chamber, capable of being pressurized during the override operation, into which an occupied innerduct is attached. The existing cable is routed through a cable seal and out of the junction box. The other branch of the junction box is connected to a short length of innerduct connected to the Tornado cable blowing machine. The route from the Tornado cable blowing machine into the occupied pathway is continuous and complete.

Here’s a photograph of the J-Box with the lid removed to show a typical setup.

junction box setup

Here’s a photograph of the J-Box in an actual field application. Note the fiber optic cable exiting the J-box and continuing on its way to the other piece of innerduct.

Junction box in use

There are a number of accessories that are required to pressurize a microduct before it is used in the override operation. The microduct plug is installed on the leading end of the microduct. There is a seal to help keep the pressure in the microduct while the threaded end keeps the plug securely attached to the microduct.

The pressurization connector is used on the opposite end of the microduct. The pressurization connector has a push to connect fitting for attachment to the end of the microduct. There is a Schrader valve at the other end of the connector to accept an air chuck.

The microduct pressurization kit is used to pressurize the microducts.  The pressurization kit’s Chicago fitting connects to the hose from the air compressor and there are air chucks on the end of the coil hoses to connect to the Schrader valve in the pressurization connectors.

Check out this guide for help selecting the accessories for pressurizing the microducts.

The microduct should be pressurized to approximately 100 psi before it is blown thru the pathway. The pressure gauge with a snap-on chuck can easily determine the internal pressure in each microduct prior to the override operation.

Be on the lookout for Part 3 of our Overriding Microduct Blog! We’ll be discussing the various microfiber cable blowing machines used to install the microfiber cable into the microduct that was placed during the override operation.

Maintenance for your Tornado Cable Blower


tornadoRegularly scheduled inspections and maintenance on your Tornado Fiber Optic Cable Blower are critical to keep it running at peak efficiency. One of the most important yet overlooked maintenance services is the proper lubrication of the drive chains. In this blog, we’ll teach you exactly what you need to know to properly lubricate the drive train of your Tornados.

Many technicians do not realize that the chains should be lubricated each time the Tornado is used. This will reduce friction from the chain and run the machine at optimal efficiency.

We suggest the application of Metaflux spray grease 70-88 (the same spray grease that is included from the factory with your Tornado)
Follow these simple steps to properly lubricate the chains:

  1. Run the Tornado at about 150 ft/min (45m/min) without any cable or applied air.
  2. Carefully insert the spray tube from the canister into the red painted holes on the operator side of both the top and bottom aluminum drive castings until the chain can just be felt.
  3. Withdrawn the spray tube about 7/8 to 1 inch (20 – 25mm) and spray for approximately 1 second.

WARNING: Do not over lubricate, as this may lead to the drive belts becoming contaminated with lubricant. If contamination does result, thoroughly wipe the belts clean before attempting any blowing operation. Do not use harsh solvents. (This is based on normal use where the chains are not exposed to excessive contamination). Never use WD40 or similar sprays as these contain solvents that will wash away the graphite lubricant in the bearings.

To re-order Metaflux spray use GMP part no. 29165 at our website, www.gmptools.com.

The simple maintenance service on the Tornado is necessary to keep the machine in pristine condition. Not only will it help to prevent down time, it will prevent lost revenue in the future.

Just remember… “If the chains aren’t turning you aren’t earning!”

Visit www.gmptools.com learn more about the equipment trusted by thousands of telecom technicians everyday!

Microduct Overriding: Part 1


(illustration courtesy of Corning Optical Communications)

Microduct overriding is the process of installing a new microduct in an innerduct occupied with an existing fiber optic cable. A single microduct or multiple microducts can be placed at one time during an override operation.

The use of an existing pathway mitigates the costs of constructing a new pathway and provides an easy way to add capacity. In some metropolitan areas, lack of room for new innerduct installation requires a conduit override process. The use of an existing pathway also eliminates the permitting process typically required of new construction, so the override operation can occur quicker. For these reasons, this procedure has recently gained considerable popularity.

Major pieces of equipment are required for the microduct override operation, they are:

  • A Conventional Fiber Optic Cable Blowing Machine
  • A Junction Box — A precision-machined piece of equipment that provides for the insertion point of the microduct into the existing pathway
  • An Air Compressor— Provides the compressed, filtered and conditioned air for the transport of the microducts through the occupied innerduct

The GMP Tornado is a conventional fiber cable-blowing machine with a design proven by decades of field use. Without any modifications, it has the ability to blow a single microduct as if it were a piece of fiber optic cable.

The Tornado can also be modified to install multiple microducts at one time, with the requisite components based on the number and size of the microducts. Typically, the sizes of microducts used in an override operation are 12/10 or a 10/8.

Check out this customer video to see The Tornado in action:

Check out this guide for help selecting the components for a Tornado conversion to tube blowing.

Our cable blowing experts are ready to help you configure your Tornado, whether you want to blow a single microduct or multiple microducts at once. Call GMP today to start enjoying the benefits of the microduct overriding operation.

Be on the look out for Part 2 of our Overriding Microduct blog! We’ll be discussing the junction box and other microduct blowing accessories required for a microduct override operation.

The Importance of Lubricant for Cable Blowing Success


If something is “as slippery as an eel” it is hard to pin down. But when it comes to Cable blowing, let’s commit to this: lubricating your duct is crucial for successful cable blowing. Slippery is good.

There are many different factors needing attention in order to achieve the best possible cable blowing job. In our previous blog, we discussed the importance of having the ideal fill ratio in order to ensure a productive cable blow. Along with the correct fill ratio and of course pressure-tight duct splices, lubrication is one of the most important success factors of cable blowing. In this article we will discuss the reasons why lubricant is necessary to blow cable the right way, the first time.

It is important to use lubricant in cable blowing because it reduces the frictional drag between the cable and duct. Essentially, the lube helps reduce friction that can build up when you pull cable around corners or through innerduct, helping to prevent damage.

Lubricant is absolutely necessary for longer cable blowing runs. The use of lubricant will measurably increase the length of cable that can be blown in a single shot. This increases the efficiency of your team and reduces the time it takes to complete a job.

Without lubrication, the friction between the fast moving cable and the stationary duct could impede the distance attainable or worse, cause cable damage. The cable can fold over in the duct, sometimes causing enough damage to need a replacement, halting the job and costing your company a lot of money.

One more thing to know is that lubricant for cable blowing is very different from lubricant for cable pulling. Never use pulling lubricant for cable blowing.


GMP offers two lubricants:

Polywater® Prelube 2000™ [1]

  • Proven superior to paraffin oils and cable pulling lubricants for cable blowing. The use of this lubricant results in longer installation distances
  • Proven and recommended by GMP and CBS Products for our blowing equipment – it increases installation distance on of our machines.
  • More economical than pre-lubricated duct. It is fresh lubrication in the field that is quick and easy.
  • Compatible with common fiber optic cable jackets.

Polywater® Prelube 5000™ [1]

  • Easy to use. It can be squeezed into small diameter microducts.
  • Works at extremely low coating levels. It coats further and more effectively than conventional blowing lubricants.
  • Proven superior in side-by-side testing in blown micro cable installations.
  • Compatible with known micro cable plastic jackets. However, it should not be used for resin-coated fiber cables.

Since 1936, GMP has been a top provider of durable and long lasting tools that can get the job done right. Our Cable Blowing Machines are designed for maximum efficiency to successfully complete even the toughest jobs. To learn more about our cable blowing products and accessories, visit our website at www.gmptools.com


Aerial Work Safety and the Tools Needed to Get the Job Done Right


When a technician is required to go above ground, safety is a necessity. Whether you are lashing cables, fixing infrastructure, or installing new wire, the importance of durable tools is paramount to ensure crew safety and a successful workday. Accidents can result in delayed job completion or worse, serious injury, making faulty equipment unacceptable.

For aerial technicians, safety matters most. Falling from the top, electrocution, or dropping equipment on other workers are all accidents that can be easily avoided with up-to-date equipment and proper safety measures and precautions. Accidents can delay or even halt daily operations. Delays can cost contractors significant dollars, and damage professional reputations, meaning being proactivity rather than reactivity can save you time and money. For these reasons, GMP manufactures high-quality equipment with workers in mind. Technicians and contractors can rely on these GMP tools to go the distance:

1. GMP D Cabinet Balcony – Our newest pole mounted work platform, the GMP D Cabinet Balcony was designed to accommodate the new generation of fiber optic electronic cabinets as well as the existing line of cross connect cabinets.

2. Model E Ladder Support – Used for securing the upper end of an extension ladder at a comfortable work distance away from the cable and strand. The Model E ladder support consists of two screw clamp assemblies, grooved to fit the strand and permanently attached to a U shaped aluminum alloy member with a single rail fitting, ensuring safety for technicians operating on a ladder. It also features a safety rope and two tether chains for added security.

3. Model B Ladder Platform – Consists of a 7 ply 3/4 in. marine plywood seat hinged to a welded pipe frame, the Model B Ladder platform is used to provide a sturdy work platform that attaches to a ladder for the craft person performing work.

If you or your employees are heading above the streets, make sure your tools and equipment are durable and up to date — the consequences could be fatal. A technician is only as good as their tools, which is why GMP takes great pride in our line of tools and equipment that set the standard for durability and reliability.

As a general reminder:

Tethers: Always wear a body belt and safety strap when working aloft. It could mean the difference between a little embarrassment and a bad fall if your ladder or platform should give out.

Practices: Your utility company wrote them for one reason: to protect you! Be sure to know all the practices that apply to your work before you begin each job. It doesn’t take long, it’s easy to do, and it’ll help protect you, your company, and your community if something goes wrong.

Since our founding in 1936, GMP has stood as a leader in telecom engineering, and has pioneered technologies that are safer and more effective in constructing the nation’s vast communications and power distribution grids. To discover more essential tools for your toolbox, visit us today at gmptools.com or call us at 215-357-5500.

The Perfect Fill Ratio for Fiber Optic Cable Blowing

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Fiber optic cable blowing isn’t a new technique for cable installation and, in fact, it has been in use since the late 1990’s. However, the cable blowing technique may be new to some installers. Machines such as the Fiber Optic Cable Blowing Machines offered by GMP [1] help get the job done with ease for both the seasoned installer or the greenhorn. In this article, we discuss one of the key parameters to a successful installation, the fill ratio.

The Fill Ratio

The fill ratio can be calculated for a single fiber optic cable installed in an innerduct or microduct as: d2 ÷ D< 65%


d2  < 65%

The lowercase “d” stands for the outer diameter of the cable, while the uppercase “D” stands for innerduct’s inside diameter.

This means that when the cable outer diameter squared is divided by the innerduct inside diameter squared, the outcome should be less than 65% (or .65) for the most effective cable blowing. Also, the fill ratio should not fall below 35%, as the cable may have more of a tendency to “kink” in the innerduct due to excessive turbulence. Likewise, when the fill ratio is greater than 80% it becomes increasingly likely that there is insufficient space around the cable for the viscous drag principle of the air to act on the cable jacket.

The fill ratio is one of the parameters determining how far a fiber cable can be blown. A larger fill ratio is preferred when the cables are relatively stiff and the duct run is straight. A smaller fill ratio is typically preferred when there are multiple bends in the duct run, allowing more room in the innerduct for the cable to navigate the route.

The installer doesn’t specify the innerduct or the cable, but the installer can easily calculate the fill ratio and determine if the ratio is in the “sweet spot” or not. A fill ratio out of range may explain why the cable installation didn’t proceed as planned.

Tools for Fiber Optic Cable blowing

GMP offers a range of cable blowing machines for conventional fiber optic cable and micro-fiber optic cable. The Tornado and JetStream install conventional fiber optic cable as well as micro-fiber optic cable. The AirStream, Breeze and Whisper install micro-fiber optic cable. The AccelAir2 rounds out the product offering and installs the smallest of fiber optic cables.

Since 1936, GMP has been a top provider of durable and long lasting tools that can get the job done right. Our Cable Blowing Machines are designed for maximum efficiency to successfully complete even the toughest jobs. To learn more about our cable blowing products and accessories, visit our website at www.gmptools.com

How and When to Use a J2 and J2B Cable-Lashing Machine

As explained in our previous blog Best Practices For Aerial Cable Placement, the stationary reel method may be used when attaching initial cable to a strand (new construction) or when attaching cable to an existing lashed cable and strand (overlash construction). This guide will help you to understand the difference between our standard J2 Lasher and the J2B.


The J2, shown above, is the original “system standard” cable lasher for cables up to 3 in. (76 mm) on strands 1⁄4 to 7⁄16 inch. This machine has overlashing capability with the turn of a lever to swing the strand lock out of the way. Its positive internal gear-to-gear mechanism has no chains or belts to stretch, slip, or break making it both safe and effective. It also has a positive mechanical brake that prevents lasher reverse until the brake is released.

At 46 lbs., (20.9 kgs) it is light enough to maneuver with relative ease. Constructed with heat-treated, plated steel, stainless steel, brass, bronze and aluminum components, it’s durable enough to last a lifetime. Because of the featured strand lock, we recommend the J2 lasher for technicians that perform both new construction on bare strand and overlashing.

The J2B, pictured below, is similar to the J2, however it is designed strictly for larger bundle overlashing. When overlashing consists of larger bundles, the strand lock of the J2 lasher can potentially interfere with the cable passing, even when the strand lock is in the open position.

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The first thing you will notice about the J2B is the widened drive housing opening and the removal of the strand lock. The strand lock is only used for new construction and not for overlashing, and since the J2B is strictly for overlashing larger bundles, it was removed completely.

Lineman have told us that when there are multiple cables lashed together, part of the bundle has a tendency to migrate up towards the strand. The J2B has a relieved drive housing, giving the cables more room to move freely, preventing interference.

There’s also a removable handle that mounts to the front of the J2B’s drive housing. This provides a stable and accessible “grab point,” allowing the technician to comfortably use both hands to transfer the lasher around the pole.

GMP lashing machines withstand the test of time with routine repairs and maintenance. The J2, J2B, and every GMP tool are fully serviceable to “good-as-new” specifications at our factory and at factory-trained service locations around the globe.

Find out more at gmptools.com or call us at 215-357-5500.

Manhole Safety: Featuring A Suite of Tools Needed to Get the Job Done Right

When working underground, preventing accidents should be your top priority. Mishaps happen, but work site safety could be the difference between a minor slow down and a catastrophe. Taking safety precautions can prevent a number of accidents from occurring, but when your own safety is out of your control, trust in reliable and durable tools is essential. Of all the potential dangers, there’s no excuse for shoddy tools to be among them. Tools become an extension of your body, like a new limb, and relying on faulty equipment could have fatal consequences.

When building telecommunications networks, every second counts. Delays can cost contractors significant dollars, and damage professional reputations. These reasons are what drive GMP to manufacture high quality equipment with the worker in mind. Technicians and contractors can rely on GMP tools to go the distance.

Here’s our list of underground equipment to ensure a safe and productive day under the manhole. All products can be found on the GMP website.

1) The E-Z Lift Cover Lifter – The tool of choice by major telecoms for removing and replacing manhole and pull box lids. The built-in mechanical advantage allows you to remove even the most firmly embedded cover, while letting the lifter – not your back – do the work. In addition, GMP offers several other cover lifter designs. See our full range at http://www.gmptools.com/nf/index_underground.htm

2) Steel Manhole Guard Rail – This high-quality barrier helps protect field crews when working in and around open manholes. Each guard has a durable, bright yellow finish for extra safety.

3) Mud Bucket – The fastest way to clear a manhole vault of mud and silt that can’t be cleared by a pump. MIG-welded aluminum articulating bucket catches up to 5 quarts in a single catch with 9 ft. handles.

4) Submersible Pumps – Our pumps are ideal for dewatering construction sites or for all-around use in industrial plants and utilities. They have a slim-line design, enabling the operator to easily fit them into casings as small as 8″ (203 mm) in diameter. Top discharge also provides maximum motor cooling for continuous duty applications.

5) High quality ventilators to supply continuous fresh air circulation for ventilation of manholes and other confined work spaces.

6) Adjustable Manhole Shield – This one tool will give you additional safety when working around manhole openings ranging from 24 in. (610mm) to 38 in. (970mm) in diameter. It provides a barrier to prevent items on the surface such as tools or supplies from accidentally falling down onto workers below. Its cast aluminum clamps let you adjust fit all manhole frames within its diameter range.

7) Cable Bending Tool – This highly versatile cable bender will help you create bends in cable up to 3½ in. (89mm) when you’re setting up cables in cable vaults. The two bronze saddles and seven position handle let you get the bend you need even when working in tight quarters.

If you’re headed beneath a manhole in the near future, GMP has a suite of tools and equipment that are ensured reliable. The importance of consistent tools is paramount to ensure crew safety and a successful workday. A technician is only as good as their tools, which is why GMP takes great pride in our line of tools that set the standard for durability and reliability

Since our founding in 1936, GMP has stood as a leader of telecom engineering, and has pioneered technologies that are safer and more effective in constructing the nation’s vast communications and power distribution grids. To discover more essential tools for your toolbox, visit us today at gmptools.com or call us at 215-357-5500.