Frequently Asked Questions

Below is a list of answers to frequently asked questions. If you have any questions that is not addressed here, please let us know.

Purchasing and Ordering

Does Nook have a minimum order amount?

Nook Industries does adhere to a $100 net/minimum order point.

What is Nook's return policy?

Our return policy is detailed on our website, www.nookindustries.com, under the 'Customer Care' tab, and select the 'Service and Support' option from the dropdown. There you will find the RMA/Return Goods Information at the bottom of the page.

Can Nook ship same-day?

We try to accommodate all rush orders for stock product. Please call our sales team at 800.321.7800 to check availability.

Does Nook participate in blanket orders?

We do our best to support your production requirements. Blanket orders help us to plan for your in-house material requirements and also help you to capitalize on cost savings associated with committing to higher volumes.

Does Nook drop ship? If so, is there a fee?

Nook is happy to ship directly to your customer at no additional charge.

What’s the lead time for Nook products?

Because many of our products are customized in some way, the lead times vary by product line. Catalog items are generally available for immediate shipment; please contact our sales team at 800.321.7800 for standard lead times and expedite requests.

Who do I contact for local support?

Nook Industries’ does have a network of representatives available throughout North America. Our representatives are ready to assist you in the field for training, design considerations, and aftermarket support. Please call us at 800.321.7800 for contact information relevant to your territory.

How do I determine the correct size product to use for my unique application?

Nook Industries’ website has a variety of tools available at www.nookindustries.com (under the ‘Engineer Tools’ tab) that are useful in determining product suitability. For live engineering assistance, our sales engineers are available by phone, 800.321.7800, or email, sales@nookind.com. You can also configure custom assemblies by clicking on the ‘2D/3D’ tab from the homepage, select a product, and you will be prompted through a process that will allow you to review available configurations, accessories and options and to customize an assembly exclusive to your needs. The software will generate a drawing for you to download and also a part number so that you are able to request a quote.


General Product Questions

What markets does Nook serve?

Nook Industries manufactures linear motion products that can be used in many markets including: Military and Defense, Aerospace, Communications, Electronics, Semiconductor, Medical/Diagnostic, Automotive, Transportation, Tire Manufacture, Steel, Chemical, Food and Beverage, Forestry, Packaging, Paper, Factory Automation, Tooling and Fixturing, Converting.

What product lines does Nook manufacture?

The engineered linear motion products and services offered at Nook Industries include: Ball Screws/ Ball Nuts, Roller Screws, Acme Screws, Mechanical Actuators, Screw Jacks, Electric Cylinders, Compact Cylinders, End Bearing Supports, End Machining, Self-Aligning Linear Bearings, Hard Shell Linear Bearings, Slide Systems, Hardened and Ground Shafting, Standard and Low Profile Support Rails, Precision Locknuts, Ball Splines.


Product Questions

Are your products clean room compatible?

This depends on the specific classification of the clean room in which our product(s) will be used. Many of our products are capable of being used within clean rooms with a US FED STD 209E cleanroom standards classification of 1000 without any special modifications. Our Teflon coated products are specifically designed to be used in these types of environments.

What is back driving and should I be concerned about it?

Normally, acme screws are used to convert rotary motion into linear motion. Back driving is the result of the load pushing axially on the screw or nut to create rotary motion. Generally, a nut with efficiency greater than 50% will have a tendency to back drive. If a self-locking assembly is required, select a nut with efficiency below 35%. CAUTION - Vibration can cause any acme screw assembly to creep or back drive. When using lead screws, applications should be analyzed to determine the necessity of a brake, especially when the possibility of injury may occur.

Do your products require lubrication?

This depends on the type of product. Many of our products are designed to be self lubricating with no need for additional lubrication or external grease. These products are designed to require no maintenance. We offer various lubrication options and the best solution will most often depend upon your particular application requirements.

What materials are your products made from?

We are capable of manufacturing our products using a variety of materials and can customize a solution that is specific to your needs. Our standard products are manufactured from...

What are the benefits of Teflon coating?

This depends on the type of product.

Where does Nook get the raw materials for its products?

Nook makes it a priority to get the raw materials for its products from locally owned businesses and suppliers. This is so we are able to have more control on the high level of quality that we use in manufacturing our products.

I need a working stroke of 10 inches, what stroke should I use in sizing?

a. Nook Industries recommends that actuators are sized two inches (50mm for metric products) longer than the working stroke. This will allow room for end of travel switches and prevent actuator from bottoming out.


Acme and Lead Screw Products

Do you offer bellows for ball screws?

Yes, Nook Industries offers bellows boots for ball screws.

Does the screw and nut need to be lubricated?

Yes, we offer high quality lubricant for you ball or acme screw application.

What is the difference between Pitch and Lead?

Pitch is the measurable distance between screw grooves. Lead is the linear travel the nut makes per screw revolution. The pitch and lead are equal with single start screws. The pitch is ½ the lead in two start screws.

For extra strength, should I use an extra long nut instead of standard nuts?

In theory, yes it would be better, but in practical terms it wouldn’t. The standard length nuts that are offered in the Nook Industries catalog offer the best price/ performance ratio. When using extra long nuts, special gauging and tooling is required for them to work properly. Fit up problems typically occur when using extra long nuts, which creates hot spots that have the ability to expand thermally under load and also bind locally on the screw. However, larger diameters should be considered if capacity is a major concern.

Are alloy ACME screws better than medium and low standard carbon steel screws?

The Alloy 4140 Heat Treated Screw is favorable only with certain applications and is frequently "over specified." This is typically attributed to the fact that it is an extremely popular material for fastener threats and bolts. Numerous users specify Alloy 4140 HT with the intent of extending the screws wear life; but the majority of screws are used with either plastic or bronze nuts and there is a large hardness differential between these materials and all steels meaning that the performance of the nut materials is not changed.

Are end-machining services offered at Nook Industries?

Yes. Nook Industries has a 120,000 sq-ft manufacturing facility located in Cleveland, Ohio, with multi-axes CNC machines dedicated to machining Acme and hardened Ball Screws.

What materials are used to manufacture Nook screw products?

Nook Industries utilizes materials that efficiently produce superior thread finish while also integrating excellent machinability. Acme, Trapezoidal Lead, and Hi-Lead screws: Screws with diameters of 1" or greater are made from 4150 steel. All stainless steel screws are made from 300 series stainless. The two classes of fit described in the ANSI standard for ACME screw threads are “Centralizing (C)“ and "General Purpose (G).” The General Purpose fit allows for the nut and screw contact interface to take place on the thread flanks while simultaneously providing clearance on the minor and major diameters. On the other hand, the Centralizing fit allows for contacting on the major diameters while also maintaining the same thread flank contact as the generalizing fit. There are minor differences between C and G when being used for applications solely of axial loading.

Is it possible to expand a ball screw’s load capacity?

Yes, it is possible to increase a ball screw’s load capacity. There are 6 general guidelines that will permit an increase in load capacity. A larger load capacity can be reached by expanding: nut length, screw diameter, amount of internal balls, lead, or by utilizing internal balls with a great diameter.

How frequently should ball screws be lubricated?

Ball screws should be routinely examined for adequate lubrication integrity and quantity. Additional lubricant will be required if the ball screw is not wet with lubrication.

Are there any distinctions between a left or right handed thread?

Typically, unless stated otherwise, ball screws are right handed. There are occasions where a left and right hand screw will be used simultaneously to permit travel in both directions while using only one motor.

Is it possible to determine if a ball screw is grounded and rolled by looking at it?

Yes, the simplest way to do so is by examining the ball screws outer diameter. There may be a fold or line (known as the witness line or crest line) present where the material has been dislocated for formation of the screw. If so, then the ball screw is rolled.

What are the benefits of Nook Industries internally ground ball nut threads?

The internally ground ball nut threads manufactured by Nook Industries assure lead efficiency, improved surface finish, and consistency in thread geometry. This guarantees that the ball nut will have superior load sharing, and that it will run noticeably smoother over the entire screw in comparison to a non-internally ground ball nut.

How often should I lubricate a ball screw?

Regularly. Regularly checking for adequate lubrication levels and ball screw integrity can help prevent issues. It is important that the Ball screw remain soiled with lubrication if there is a lack of lubrication on the screw additional quantities should be applied.

How do I decide which type of screw product to use? Acme vs. ball screw for my application?

Screw type selection is dependent on many factors that include but are not limited to, application load, desired speed, accuracy/repeatability requirements, and application environment. For help in selection please contact Nook application engineering.

Can ball screws be used in vertical applications without back driving?

No. Ball screws in vertical application must be used with a brake motor to prevent back drive.

Is lubrication required on lead screw products?

Yes – proper lubrication must be provided to achieve satisfactory service life. Nook PowerAc lubricant (E-100 spray lube or PAG-1 grease) is recommended for acme screw applications.

Are lead screw products able to be used in harsh environments.

Nook PowerAc acme screws and nuts do not utilize any rolling elements and are thus forgiving to harsh environments. The sliding element to an acme screw allows for operation in such industries as paper handling, wood and metal cutting, and food processing.

How can the backlash be minimized or eliminated in a ball screw assembly?

Backlash is typically eliminated by utilizing a preloaded ball nut. Preloaded ball nuts are typically only available with precision rolled screw stock or precision ground screw stock. To minimize backlash on a standard ball nut, it is permissible to have the ball bearings in the nut “select fit” to .003” - .005”. CAUTION – select fitting may result in lower life.

My ball screw assembly failed prematurely, why?

Premature failure may be caused by any of the following:

A) Misalignment of the ball nut to screw which results in side loading or eccentric loading will reduce life. This may cause the bearing balls to split or get flats on them. The ball bearings may even break out of the return tubes.

B) Metal chips, dirt, or debris in the ball nut may impede the ball bearings from free circulation. The bearing balls may get flats on them because of skidding.

C) Lack of lubrication: Proper lubrication will help dissipate heat and reduce metal-to-metal wear of components.

D) Excessive speed: Exceeding the ball nut critical speed can break pickup fingers off causing the balls to come out of the nut. Exceeding the screw critical speed will cause the screw to whip resulting in misalignment.

What is the amount of backlash for a single, standard, non-preloaded ball screw?

Typically, the standard amount of backlash is in the range of .003 inches to .015 inches.


Linear Actuators

Can I run the linear actuator into a hard stop?

This is not recommended on the finer pitch resolutions due to the high forces generated which may cause lock-up. It is possible however under reduced power input.

Will I need to relubricate the leadscrew or shaft on the linear actuator?

The linear actuators are lubricated by the factory for the life of the product and do not need re-lubrication under normal operating circumstances.

What can I do to extend the life of the actuator?

Reducing the load, avoiding side loading and proper mounting will all help extend the life.

What may be the problem if an actuator with a brake is not holding the load?

Verify the holding force of the actuator is not being exceeded. Check to see if any moment loading is being applied to the brake. Moment load prevents the wrap spring from fully engaging, and the load will coast. Ensure the power to the unit is being fully cut.

What is the difference between static load and dynamic load?

Dynamic, working, or lifting load is the force that will be applied to the actuator while it is in motion. Static load, also called holding load, is the force that will be applied to the actuator when it is not in motion.

Can Linear Actuators Have Limit Switches?

Linear actuators can be supplied with limit switches. The type of limit switches available varies with each product range.

Can two or more Nook CC linear actuators be synchronized?

Synchronization of standard CC actuators is not recommended without the use of a connecting shaft. Small differences in motor speed may cause the actuators to get out of synchronization. Use of clutch models allows alignment when actuator is extended or retracted.

What's duty cycle and how is it calculated?

Duty cycle is measured as the total on time vs. the total time period. Duty cycle is generally measured as a percentage of the total time in the periods. Nook recommends a duty cycle of 25% at the rated load. Max total on time should not exceed 5 minutes.

Can I adjust the speed of a Nook linear actuator in the field?

No, load vs. speed graphs are provided in the Actuator catalog. Should you need to vary the speed of the actuator, the proper electrical drive should be selected.

Can Nook actuators perform complex positioning?

Yes, the CC cylinder offers 4 different feedback options to manage complex positioning applications. A reed switch, hall effect sensor, 10K potentiometer, and encoder are all offered as configurable options to the CC cylinder.

Does the CC actuator come with a clutch?

The CC linear actuator offers a heavy-duty clutch that protects the gears and components in the event of overload and over travel. The actuator will have a ratcheting noise when the clutch is engaged.

Do Nook linear actuators require maintenance?

No the CC linear actuator is a self contained actuator that does not require any maintenance throughout the useful life of the unit.

In What Direction can loads be applied to CC Linear Actuators?

Nook CC linear actuators can be used in either tension, compression, or a combination of the two. Side loading should is not permissible and should be avoided at all costs.

What type of Motors do the CC linear actuators Use?

All of the linear actuators are supplied with DC motors. The 110VAC version of the actuator still utilizes a DC motor, however a rectifier is supplied to convert the supplied AC voltage to the needed motor DC voltage.

How often should I lubricate my linear bearings? When should I lubricate my bearing?

Frequency of lubrication is highly dependent on the application load, speed, and environmental conditions. It is not possible to over lubricate the bearings, as excess lubricant will merely exit the bearing under the seals.


Modular Linear Actuators

Are Modular Linear Actuators maintenance free?

No, proper lubrication and maintenance is necessary for long actuator life. See maintenance section of Nook Modular Linear Actuator catalog.

The belts are slipping on my belt drive. What should I do?

Most commonly belts will slip due to lack of tension. If there is not enough belt tension, the belts will slip, which can cause heat buildup and lead to premature failure. Consult Nook Modular Linear Actuator maintenance section for tensioning procedures.

Can Modular Linear Actuators be used with my existing external guidance.

Most modular linear actuators come with built in guidance and shouldn’t be combined with external guidance. There are select actuators that can be used with existing guidance systems. Nook offers the EGT/EGK/EGZ actuator as well as a special version of the QLZ actuator where existing guidance is used.

How do I calculate my overall length when I know my stroke?

Each actuator type and size shows a “basic length” in the dimensions chart. That basic length is the minimum overall length of an actuator with zero travel. You must add your travel (in mm) to the basic length along with the desired over travel amount. Nook recommends 25mm on each end for over travel. Travel + over travel + basic length = Actuator overall length.


Slide Systems

What type of lubrication should be used on Ball bushing bearings or linear systems?

Nook recommends and offers linear bearing lubricant LBL-1 that is synthetic –based oil with PTFE. It is sold in 4 oz bottles (NLU-1006) or a 12 bottle case (NLU-2006)


Shafting

What is the hardness of the shafting?

Standard alloy shafting will be hardened to Rc 60-63 while stainless steel shafting will be hardened to Rc 50-55


Profile Rail Systems and Blocks

Are linear ball bushing bearing pillow blocks sealed?

The ball bushing pillow blocks include a seal in each end of the block. This is standard for all ball bushing pillow blocks. The seal is an external seal and is press fit into each end of the pillow block.

Does Nook provide profile rail longer than the standard length?

For rails exceeding the max standard length a butt joint is required. A butt joint is made by precision machining the two ends of the profile rails to match. The rails are marked after machining and must be assembled in the same order in insure smooth transition between the rails. Butting two standard cut rails together will not provide smooth enough transition for the bearing block.

Are Nook profile rails interchangeable with other manufacturers?

Nook profile rail assemblies are interchangeable with other manufacturers. It is not permissible to place a Nook runner block on a different manufacturers rail and vice versa.

Does Nook offer special coatings for profile rails?

Yes. Nook offers Armoloy coatings as well as nickel plating on both the runner blocks and the profile rails.


Screw Jacks and Electric Cylinders

How is the rotary limit switch adjusted for position stop?

A short video of how to set the limit switch is located at: http://www.youtube.com/watch?feature=player_embedded&v=KR6Fw8O2fcgHow

Can corrosion resistant properties be supplied with Screw Jacks?

Yes, we have a specific product line of ActionJacs made of Stainless Steel materials for high corrosive areas. For details contact us, Nook Industries.

In what scenario do I use an Anti-Backlash Screw Jack?

If you are using a Machine ActionJac in an application that calls for reduced axial backlash you would want to select a model with the "Anti-Backlash" mechanism. This is typically used when minimal axial backlash is required and load direction changes from tension to compression. This design is only available for translating screw jacks. It can be combined with Anti-Rotation mechanism as well.

How can I classify the efficiency of a Screw Jack?

For specific efficiencies related to screw jack models please visit our ActionJac Catalog and select which product best fits your need. Product customization is also available for unique situations.

What makes the Nook Electric Cylinders perfect for solar actuation?

Nook’s Electric Cylinder is perfect for solar actuation mainly because it offers a high degree of precision and has been engineered to be environmentally conscience. In addition, other features of the Electric Cylinder such as: the direct feedback, direct power input, and the encapsulated screws, make it ideal for solar applications. Nook’s Electric Cylinder has also proven to be easily controlled, reliable, and durable as well.

What is the lifting torque required?

Torque required to move a load is dependent on jack selection. For your convenience Nook lists, on each jack catalog page, a “torque to raise 1 lb” (in-lbs)

Can the jack be operated in multiple units?

Yes, jacks can be linked together to mechanically raise and lower loads. Combined with miter gearboxes, motors, reducers, couplings and shafting, jacks can be arranged in multiple configurations. Some typical arrangements are shown on pages 18-21 of the Nook Worm Gear Screw Jack catalog.

How many actuator jacks can be connected in series?

This will be limited by the input torque requirements on the first worm shaft in the line, the point at which the motor connects. The torque on the worm shaft of the first actuator unit should not exceed 300% of its rated full load torque. Torque can be reduced by using a dual output gearbox at the center of the arrangement. If this is not possible, the actuators may be individually motorized and synchronized using electronic controls designed by the customer.

Can the Nook actuator jack operate at high speeds?

Each jack has a rated max input HP, this value should not be exceeded. Max RPM should not exceed 3000 RPM on a ball screw jack and 1800 RPM for a machine screw jack.

Can the Nook miter gear boxes operate at high speeds?

Standard Nook miter gearboxes should be used at 900RPM and below. Nook offers spiral cut bevel gearboxes (GB210S, GB15S, GB12S) for applications where the input RPM exceeds 900RPM.

What is the efficiency of the miter gear boxes?

For multiple jack arrangements, total horsepower required depends on horsepower per jack, number of jacks, the efficient of the gear box(es), and efficiency of the arrangement. Arrangement efficiency is as follows:

1.Two jacks – 95%

2.Three jacks – 90%

3.Four jacks – 85%

4.Six jacks – 80%

Can the Nook Screw Jacks be used for continuous operation?

Max allowable horsepower ratings are based on a 35% duty cycle for ball screw jacks and a 25% duty cycle for machine screw jacks. Continuous operation of a screw jack is not recommended.

Will the Nook Actionjac withstand a side loading?

No, Nook screw jacks are designed for axial thrust loads only. Side loadings can cause premature failure.

Can the lifting screw be keyed to prevent rotation?

The lift shaft of a translating style jack must be attached to something which prevents the lift shaft from rotating. If it is not, the lift shaft and the load will turn and not translate. A keyed jack has a keyway machined along the length of the lifting screw and a matching key is fastened into the cover of the jack. This will eliminate lift shaft rotation. The keyway in the screw causes greater that normal wear on the internal drive sleeve threads and somewhat reduces jack life. Ball screw jacks can also be supplied with a device that prevents rotation on the lift shaft. Anti-rotation is accomplished by a square guide attached to the screw translating inside a square stem cover attached to the jack. The square stem tube is supplied with lube fittings.

Can bellows boots be supplied for an actuator model with inverted screw?

Yes Nook can provide bellows. However, allowance must be made in the length of the lifting screw for both the closed height of the boot and structure thickness. Custom bellows flanges are available for mounting to your structure. Please supply a drawing of the bolting pattern needed at the time of quoting.

Can travel stops be provided to prevent screws from threading out of the housing?

Screw stops are provided standard on all ball screw jacks and can be provided as a modification to machine screw jacks. Note that screw stops are not to be used as end of travel limits but only for preventing the lift shaft from unthreading from the jack housing.

Is the actuator self - locking?

Only Machine Screw in ratios larger than 20:1 are considered to be self locking in the absence of vibrations. Vibration may cause the actuator to walk or creep. All ball screw jacks are NOT self locking and need to be used with an external brake.

What lead error is present in the lifting screw threads?

Machine screw jacks will have screw thread lead error of 0.0003 in/in screw jacks will have a screw thread lead error of 0.004 in/ft.

How do you calculate the RPM of worm shaft necessary to achieve a given travel rate?

If the application calls for a certain travel speed, the worm shaft speed which will give the rate of raise can be calculated as follows when travel rate is expressed in inches per min (in/min). Worm shaft RPM = Travel rate (in/min)*Turns of Worm for 1” travel.

How is the Nook rotary limit switch mounted on an actuator unit?

Because a small provision has to be made to the screw jack worm shaft, it is suggested that the screw jack be ordered with the limit switch assembled. Rotary limit switches are offered for sizes 2ton through 100-ton machine and ball screw jacks.

Can Screw Jacks be Supplied with Corrosion Resistant Properties?

Screw Jacks can be supplied with stainless materials as well as epoxy paints for highly corrosive environments. Please contact Nook Application engineering to help specify the correct screw jack.

How does a translating screw jack operate?

A translating jack has a lifting shaft that moves through the gearbox. A nut is integrated with the worm gear such that the worm gear and nut rotate together. When the lift shaft is held to prevent rotation, the lift shaft will move linearly through the gear box to move the load.

How does a rotating screw jack operate?

A rotating jack has a lift shaft that moves a nut as it turns. The lift shaft is fixed to the worm gear which caused the load (attached to travel nut) to move along the lift shaft.

Are limit switches permissible on Screw Jack

Yes, it is possible for screw jacks to have limit switches, but the type of limit switch supplied is dependent on the range of each product. As a more accurate and more efficient position sensing mechanism we also offer Limit switches on the tubes of our jacks (NSS).