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True-Tension Stringing Machines (TTSM)
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Maintenance Questions and Answers: 

This page contains answers to common maintenance questions that I have received in the past. I have referred to the ID Numbers of the parts referenced below in Italics. You can check what part the ID Number refers to in the Exploded Views of the Tensioning and Turret Assemblies in your manual You can also download a printable copy of these assemblies in the "Downloads" page of this site.

  1. How can I maintain my True-Tension Stringing Machine?

  2. Can I get my True-Tension Stringing Machine reconditioned?

  3. How can I obtain a parts list of the True-Tension Stringing Machine?

  4. Why does the black coating on some parts fade?

  5. Why won't my machine hold tension?

  6. Why is the pre-stretch higher than that shown on the Pre-Stretch Scale? 

  7. What adhesive is used to hold the Brake Rubber on?

  8. Why does it cost $45 to overhaul a Brake Assembly?

  9. Can I change the Brake Assemblies myself?

  10. How do I clean and adjust my clamps?

  11.  

How can I maintain my True Tension Stringing Machine?

The True-Tension Stringing Machine should be stored in a dry environment when not in use with a cover over the complete top of the machine to keep out dust and moisture.

Make sure that you store the machine with the Main Spring backed off to -0- lbs to help maintain calibration. The Pre-Stretch adjustment can be left at any setting without affecting the accuracy of the machine.

Lubricate your True-Tension Stringing Machine in accordance with the Owners Manual. Click here for Lubrication Instructions.

If your machine is operated or stored in a wet environment (high humidity) a very light coating of a water dispersing oil or wax will protect the steel metal surfaces. Items that can rust if neglected are the Glide Bars, the Pawl Block Pawls, the Brake Assemblies, and any other item made from steel even though Electroless Nickel Plated at the time of manufacture. It is very rare to see corrosion of the black hard anodized aluminum surfaces. It is also very rare to see rust in desert areas such as the Southwestern United States far from the Ocean.

Do not allow any lubricants on the Synthetic Rubber Faces of the Brake Assemblies, the Control Wheel Serrations that contact the Synthetic Rubber Faces of the Brake Assemblies, the Stringing and Pulling Clamp String Gripping Surfaces, or any other surfaces that touch the strings!

Occasionally clean the string contact points of the String Clamps, between the Long and Short Main Pulling Jaws, and the Control Wheel Serrations with Acetone.

CAUTION
: Acetone and Acetone Vapors are extremely flammable, very explosive, and can be Toxic!  Do not use Acetone without adequate ventilation, near any open flame or pilot light, near running electric motors or any other sources of ignition! Do not use Acetone without eye protection, or without approved protective gloves! Do not breathe the Acetone vapors!  Follow all instructions, warnings, and cautions on the Acetone container.

NOTE: Click here to read of the safety hazards of Acetone and how it can affect your health and well being.

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2. Can I get my True-Tension Stringing Machine reconditioned?

Normally a properly cared for True-Tension Stringing Machine will last for many years of daily use without the need for reconditioning. Machine assemblies can be shipped to us for calibration, lubrication, repairs, upgrading, or reconditioning.  A quotation of repair costs will be given to every True-Tension Stringing Machine owner prior to any repair.

Calibration Check: The current price for a Tensioning Assembly Calibration Check is $35.00 plus shipping. This does not include re-calibrating or replacement of  any parts if required.

Note: If you purchased your True-Tension Stringing Machine from Jim Larsen or purchased a new TTSM Tensioning Assembly from Jim Larsen, or had your TTSM Tensioning Assembly reconditioned by Jim Larsen, Calibration Checks are at no charge and you will only have to pay for to/from shipping.  Only the Tensioning Assembly needs to be shipped for a Calibration Check or Calibration.

Replacement of the Brake Assembly Rubber Pads:  The P/N 20104 Brake Assemblies can be overhauled with new Long Life Synthetic Rubber Pads installed and ground to the exact thicknesses and contours required using the original one-of-a-kind contouring holding fixture designed by John Balaban and later modified by Mike Schenkhuizen for the original True-Tension Stringing Machines. The cost is $45.00 per each Brake Assembly overhaul. This cost is for replacement of the Synthetic Rubber Pads only and does not include cosmetic or physical damage repairs or shipping. New complete spare P/N 20104 Brake Assemblies are available for $95.00 each plus shipping and are ready to ship. Only the new Long Life Synthetic Rubber Pads (Yellow) are being used now!

Complete Reconditioning of the P/N 20120 Tensioning Assembly takes about 8 plus hours or more and consists of disassembling as required, cleaning and inspecting all parts, lubricating all bearings with grease and all other parts requiring lubrication with grease or oil as required. The Brake Pads of the Brake Assemblies are also replaced with new Brake Pads at no extra cost. A final calibration check of the Main Spring and Pre-Stretch Adjustment is done to confirm accuracy. Cosmetic replacement of Tensioning Assembly parts will be done at the owner’s request with no extra labor costs at the time of reconditioning.

The current labor price for a complete reconditioning of the Tensioning Assembly is $600.00 plus parts and return shipping costs. The above price does not include cosmetic or physical damage repairs. Only the Tensioning Assembly needs to be shipped.

Machines received for reconditioning with damage caused by improper storage, abuse, and/or mishandling will be repaired on a time and material basis at $75.00 per hour plus the cost of parts required to bring the machine back to an acceptable condition.

NOTE:  The grease in the Bearings, Pawl Block Assemblies, and String Clamp Assemblies will, over the years, eventually harden into a non-lubricating sticky paste and cause problems. See the Lubrication Instructions page.

As evidence to the robust construction of the True-Tension Stringing Machines I've done calibration checks of True-Tension Stringing Machines that had been in service for over 20 years and found the calibration to be right on!

NOTE: Store your machine with the Main Spring backed off to -0- lbs after use to help maintain calibration. This is required of any precision measuring tool such as high quality torque wrenches that use a precision spring. The Pre-Stretch adjustment can be left at any setting without affecting the accuracy of the machine.

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3. How can I obtain a parts list of the True-Tension Stringing Machine?

Detailed exploded views of the major components, parts lists, and instruction manuals of the Model 2020 True-Tension Stringing Machine are being added on a regular basis to our "Downloads" pages.

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4. Why does the black coating on some parts fade?

Fading of the Hard Anodized Black Surface Coating, especially when exposed to direct sunlight, is a natural aging process that happens over an extended period of time and is normal for most black hard anodized coatings.  This is cosmetic and does not affect the calibration or reliability of the machine. Using a cover over the machine when not in use would retard the fading, keep your machine dust free, and keep people from touching it. In the Products page we offer a custom made to fit black vinyl cover imprinted with True-Tension in silver lettering as an optional accessory.

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5. Why won't my machine hold tension? (Updated 11/07/07)

Tensioning Assembly: The first thing to check is to confirm that the Pawl Block Pawls are properly lubricated and that the Brake Assemblies (ID#58 & ID#66) have not lost the Synthetic Rubber Pads that contact the Control Wheel (ID#47).  Confirm that the the Pawls move freely without sticking and that the Synthetic Rubber Pads have not come loose or deteriorated.

Then check to make sure that no lubricant or wax buildup on the Serrated Edge of the Control Wheel or on the Brake Assembly Rubber Pads. Wax buildup on the Serrated Edge of the Control Wheel is the main reason of slipping brake assemblies.

NOTE: I receive many Tensioning Assemblies with so much string wax buildup on the Control Wheel Serrated Edge that the brake pads slip and I have to use a small fine stainless steel wire brush soaked with Acetone to remove the buildup.  Quite often the wax buildup can not be seen. This cleanup of the wax can be done by the owner!

CAUTION: Acetone and Acetone Vapors are extremely flammable, very explosive, and can be Toxic!  Do not use Acetone without adequate ventilation, near any open flame or pilot light, near running electric motors or any other sources of ignition! Do not use Acetone without eye protection, or without approved protective gloves! Do not breathe the Acetone vapors!  Follow all instructions, warnings, and cautions on the Acetone container.

NOTE: DO NOT change the Pawl Block Pawl adjustments unless you know what you are doing and have access to a calibrated scale. Any time any Pawl Block adjustment is changed, the Brake Assemblies are changed, or the Calibrated Indicator is adjusted the Tensioning Assembly should be re-calibrated or you will be doing a disservice to the owners of the racquets that you are stringing for. You will no longer have True Tension! 

NOTE:  Many True-Tension Stringing Machines owners are using True-Tension Stringing Machines that are well over 20 plus years old that have never been back in for calibration or a good general lubrication or servicing. One major component part of these machines, the Pawl Block Assembly, can cause Tension Holding problems when the original grease dries out and hardens after many years leaving a sticky paste which inhibits the free movement of the Pawl Springs and/or the Pawls that hold and release the Brake Assemblies. Luckily the Pawls can be easily lubricated with a small drop (1 very small drop) of sewing machine oil or similar lubricating oil such as Tri-Flow which will melt out the old grease and keep the pawls operating properly. Do not overlubricate!!!!!

Do not use WD-40. WD-40 is a very light water displacement oil and not a good lubricating oil. As part of maintaining your machine the Pawls should have a very small drop of oil where they enter the Pawl Block and and also the visible small springs a couple of times a year.

CAUTION: Don’t put more than a very small drop of oil on the pawls where they enter the Pawl Block and on the Pawl Springs as the excess oil will work it’s way down to the Brake Assemblies Rubber Pads and onto the Control Wheel and slippage of the brake pads will occur.

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6. Why is the pre-stretch higher than that shown on the Pre-Stretch Scale?

Tensioning Assembly: To determine that the pre-stretch is actually higher than that shown on the Pre-Stretch Scale (ID#42) requires a calibration check. Changes to calibrated pre-stretch adjustments won't happen unless the Pawl Block (ID#61) adjustments have been changed, the Left Brake Assembly (ID#66) has been changed, or the position of the nuts (ID#15) of the Pre-Stretch Lead Screw (ID#8) has been changed. 

If you have a calibrated scale and you find that the actual pre-stretch is higher than that shown on the Pre-Stretch Scale adjustments can be made to the position of the hex nuts (#15) of the Pre-Stretch Lead Screw (#8) and/or, if necessary, the Left Short Pawl (#62) of the Pawl Block (#61) can be adjusted slightly upwards with clockwise turns of the Pawl Block Short Pawl adjustment 10-32 hex head screw using a 3/32" Allen Wrench. Insert the Allen Wrench into the bottom left hole of the Pawl Block to make the adjustment.

NOTE: I do NOT recommend any changes to the Pawl Block Pawl adjustments unless you know what you're doing and have access to a calibrated scale. Any time any Pawl Block adjustment is changed, or any Calibrated Indicator is adjusted the Tensioning Assembly should be re-calibrated or you will be doing a disservice to the owners of the racquets that you are stringing for. You will no longer have True Tension! 

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7. What adhesive is used to hold the Synthetic Brake Rubber on?

The adhesive that I use during assembly of the Brake Assembly is Barge All Purpose Cement manufactured by the Quabaug Corporation of North Brookfield, MA 01535.

Many adhesives have been tried over the years and we have found that Barge All Purpose Cement holds without failing for many years! It is inexpensive and a two ounce tube can be readily found in most hardware stores.

Many True-Tension Stringing Machine owners have found that 2-part Epoxy Cements have also work fine if allowed to fully cure. Always allow the full cure time recommended by the Cement manufacturer before applying tension!

I continue to experiment with new adhesives that are readily available to the public and which hold without failing for many years.

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8. Why does it cost $45 to overhaul a Brake Assembly?

Short answer: To make them work properly!

Long Answer: On a properly maintained True-Tension Stringing Machine a quality Long Life Brake Pad should last for many years of stringing thousands of Racquets. When you consider the fact that the custom ordered Synthetic Rubber from which the Brakes Pads are manufactured comes in sheets that are 3' wide, 4' long and 5/16" thick. These sheets then have to be cut by Extreme High Pressure Abrasive Water Jet to 4 foot long bars 0.635" wide from which I then have to cut to 0.500" lengths. After that the mating surfaces of both the Brake Pad and Brake Assembly Shoe have to be prepared for the adhesive, cemented together, and let cure overnight. Each Brake Assembly is then mounted in a one-of-a-kind grinding jig and each Brake Assembly is custom ground on a Vertical Belt Grinder that guarantees that the proper Brake Pad contour and thickness are maintained.

All Brake Pads are then installed and custom ground to the proper  contour and thickness one at a time! This is a two day process to allow the adhesive to cure.

Brake Assembly Shoes, like most everything manufactured in the world today, have a manufacturing dimensional tolerance per the original drawings which the Brake Pad Contouring Fixture corrects for when grinding the proper Brake Pad contour.  A properly ground Brake Pad makes up for that possible Brake Shoe ± 0.010" dimensional tolerance. That's why finished Brake Assemblies have Brake Pads that might be thicker or thinner than others when properly ground as no manufacturing dimensional tolerances are allowed between each Brake Assembly mounting hole centerline and the outer edge of the properly ground Brake Pad that contacts the Serrated Edge of the Main Control Wheel. This dimensional difference is hardly  discernable to the naked eye but makes a real difference when you are stringing with high tensions!

Let's face it, as a professional stringer you can't afford to string racquets for free nor can I afford to sell parts for less than it costs me to manufacture or overhaul them. Most True-Tension Stringing Machines owners have been extremely happy to have replacement parts and maintenance support available again for their True-Tension Stringing Machines.

Note: The new Yellow Synthetic Brake Pads have been shipped worldwide since September 2006 without a failure dientigration. They are holding up fine just like the Original black Synthetic Brake Pads that were originally used back in the 70s and early 80s. In the following years a cheaper genericSynthetic Brake Pad material was used and until I changed over to the new yellow Synthetic Brake Pads many hundreds of Brake Pads disintergated even if not used whereas the old Original black Synthetic Brake Pads are still in new condition some 30 years later. See: New Yellow Brake Pads

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9. Can I change the Brake Assemblies myself? (updated 11/07/07)

Yes. Anyone with manual dexterity and mechanical ability using common sense and basic hand tools can change the Brake Assemblies.  Use needle nosed pliers or strong Heavy Tweezers to properly refit the Brake Assembly Springs. DO NOT mix up the Springs as they are different!  Make sure that you re-check the calibration afterwards. Most of the time the calibration won't be effected by changing of the brake assemblies. Don't stretch, destroy, or lose your Brake Assembly Springs. They are in very short supply!

NOTE: I have found Tensioning Assembly Calibrations off by up to 15 pounds after owners have changed the Brake Assemblies by themselves, then attempted to adjust the pawl block, and finally sent their Tensioning Assembly in for calibration after racket owner's  noticed a difference in their racquet performance.

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  10. How do I clean and adjust my clamps?

For an explanation on how to properly adjust the True-Tension Stringing Machine Clamps click here . String clamps should not slip if properly cleaned, lubricated, and adjusted.

Contact Jim Larsen if you have string slippage after cleaning and adjusting your TTSM String Clamps.

See my 08/07/07 update regarding 17 and 18 Gauge Strings slipping in the String Clamps.

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Email:jim.larsen@hughes.net
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This site is maintained by Jim Larsen -- last updated on 10/30/14