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Kurt Tip of the Month (2005)

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December 2005

Vise Maintenance - Every 6 to 12 Months:

1. Open the vise until you are able to insert the long of a hex wrench into the socket head set screw in the backside of the movable jaw. Note: the backside of the movable jaw has (3) tapped holes.
2. Loosen the setscrew but do not remove. Turn out until the face of the setscrew is approximately 1/4" to 3/8" beyond the backside of the movable jaw.
3. With the hex wrench still in place, lift upward allowing the movable jaw to pivot off the nut. Note: There is a segment in the shape of a half ball in the movable jaw cavity, be careful not to misplace while cleaning. Remove all chip guards (See chip guard caution).
4. Clean out any chips that may have built up underneath the movable jaw in the center ways of the vise bed.
5. At the end of the vise with the hex screw, remove the spiral-retaining ring (earlier style vises used a threaded collar). Slide forward the nut and screw assembly exposing the thrust bearing assembly. Remove bearing assembly and re-apply bearing grease.
6. Inspect brush seals and or wiper seals. Remove any chip build up.
7. Re-assemble screw and nut assembly installing the retaining ring. You may need to pull up the nut assembly to get the retaining ring into the grooove by lifting upwards at the angled portion of the nut.
8. Oil all exposed surfaces of the screw and a small film to the top surface of the vise bed.
9. Apply a generous amount of grease into the cavity of the removed movable jaw and place the half moon segment back in place. Align flat approximately to the same angle of the nut. The flat surface will match up with the angle of the nut once reassembled.
10. Reinstall the moveable jaw assuring the segment is properly in place
11. While pulling back on the moveable jaw, pull it against the segment and re-tighten the setscrew.
12. Once the setscrew is tightened, back it out approximately 1/8th of a turn. This setscrew must not be tightened all the way down. If jaws move hard, loosen setscrew another 1/8th turn.
13. Close movable jaws tightly. This will 'set' the segment to its proper orientation alignment. Open the movable jaws and re-check the setscrew for proper tightness. Again, do not over tighten.

November 2005

Daily/Weekly Vise Maintenance:

1. Clear all free standing machined chips in and around the vise bed.
2. Visually inspect all screw brush seals for cleanliness.
3. Air-dry and apply rust inhibiting oil to the top surface of the vise bed.

Monthly (1 to 3) Vise maintenance:

1. Visually inspect for chip entrapments as applicable.
2. Visually inspect all screw brush seals for cleanliness and wear. All vises have a brush seal in the nut on the handle end of the vise. Some vises have a brush seal on both ends of the nut. These brushes “sweep” chips from the screw threads.
3. Air-dry and apply rust inhibiting oil to the top surface of the vise bed. Completely open and close the movable jaw, The applied oil will help keep rust from forming in and underneath closed areas and lubricates the threads in the nut.

Coming in December Maintenance Tips for 6 to 12 months

October 2005 - A More Palletable Method Of Workholding

New View Of The Workholding Process
Leads To Hybrid Pallet Vise Design

"Longtime users of standard Kurt vises sometime ask us for a more robust workholding alternative," reports Michael Granlund, Kurt Custom Sales Engineer. "Our 6 inch pallet vise design takes the best of our standard vise and pallet designs and are combined into a streamlined, hybrid version that has the rigidity and precision of ductile iron in a low profile with an air actuated mounting mechanism that fastens quickly to a machine table. (read more)

September 2005 - Reduce Tool Change Time By 75 Percent on Knee Mills

Automate your knee-type milling machines for faster and easier tool changes using Kurt Automatic or Mechanical PowerLock® Drawbars. They greatly improve milling machine output by reducing tool change time up to 75 percent. Spend more time in the cut and less time changing tools.

To operate, just insert the tool and push a button on the Automatic Model or push a lever on the Mechanical Model. Both models assure fast, uniform collet tightening without the need for hand tools and manual tightening. The Kurt Drawbars prevent under tightening and tool slip or over tightening and drawbar breakage.

These Kurt Drawbars have operator-friendly design to reduce milling machine operator fatigue, increase safety while improving productivity, and eliminate operator stretching for tool setup. In addition to providing consistent torque on the drawbar rod, these Kurt Drawbars eliminate drawbar tapping to free tool in the collet.

Available in automatic and mechanical models, Kurt PowerLock Drawbars can be operated with existing tooling. (They operate R-8, #30 and #40 taper toolholders. Additional special toolholders are not needed). These Kurt Drawbars are easy to install on most milling machine models. They operate on shop air supply. A filter/lubricator, regulator and gauge are included with most models. (read more)

August 2005 - Workstops are receiving more attention than in the past. The reason is that in multiple vise set ups, jawplates can be interchanged quickly without loosing the location of the attached workstop.

A) On occasion, the need to locate more than one work piece in one jaw location requires that the workstop be extremely small, thus consuming little or no space between the parts so as not to interfere with adjacent vises. A vise jaw with a groove in its top face is available as a receiver for a work stop that cost-effectively fulfills these requirements.

B) Work stops attached to a threaded hole in the outside edge of a jaw plate work well for many applications. They are not suitable for multiple parts in one jaw set and do not allow vises to be located without a space between them. The same is true for similar workstops mounted along the vise body edges.

July 2005 - Higher quantity lot sizes make multiple vise set ups desirable.

The work piece size determines the spacing between the vises as well as the vise size itself. Generally attempts must be made to produce the maximum amount of parts per cycle. Many additional operations by the same operator can then be done simultaneously. The key to freeing the operator is quick clamping and the highest efficiency of the work piece loading cycle. This includes prepping the work area for thorough chip flushing and cleaning. There are times when the NC machine can be programmed to flush the chips with programmed moves. Other ways to keep the machine in the cutting mode on smaller parts include palletizing the workpieces and then exchanging pallets in the vise as a pallet receiver. The actual workholding in these applications is best done with miniature wedge clamps that have similar features as the original “Anglock. These wedge clamps will not loosen under vibration and can clamp two parts with the turning of one screw.

Deciding to use a multiple vise setup requires considering the cost of the set up itself. When using a multiple vise setup, it is common practice on large quantity lot sizes that repeat periodically to mount the entire setup on a base plate or tombstone so it can be stored intact between uses along with all the cutting tool holders. When this is not feasible, grid plates with dowel hole patterns are kept on the machine. Vises are then easily located and fixed to the plates. This allows the setup to be guided by the spacing and the dowel patterns.

View Custom Engineered Workholding

June 2005 - Jaw plate considerations affecting part contact and set up repeatability

A) The simplest and most commonly used jaw plates are case hardened. They are mounted with socket head cap screws. They fasten the plate to the jaw block with bolts on the inside of the clamping face. This style of jaw plate is best suited when higher than standard jaw plates are required. These plates are available in many variations including magnetic inserts which hold parallels from moving.

B) Vises equipped with indexable carvable jaw blocks or which index opposite jaw plate mounting faces can present a new jaw face in less than 10 seconds per jaw. All that is needed to make the change is a standard. screwdriver to lift the jaw block off the vise bed, rotate to a new side, reposition it and snap it down. The stationary block has top mounted screws for repositioning which takes care of two jaw faces when the change is made.

C) Serrated jaw plates in all of the above configurations are useful for holding raw stock material where marking of the work piece is allowed. Generally these are for extremely heavy material cuts.

D) Shaped jaws, typically V-shaped with different V-depths machined horizontally and vertically on the jaw faces, will allow holding one or two round parts of identical size either perpendicular to the vise bed or parallel to the vise base. Again, mounting can be standard front-face and counter bored for the bolt heads. Step jaws also belong in this category. They are popular because they replace parallels and they do not have the residue buildup problems that parallels present. Neither are parallels practical on tombstone or production CNC applications.

Plus many more options are available to fit most applications. Click here to read more.

May 2005 - Workholding For Simple Machines Such As Knee-Type Mills

Knee Mills are a favorite of most toolmakers and "model shop" machinists. In this environment, lot sizes are small and setups are constantly required. Under these circumstances, a versatile workholding system employing vises will save considerable time. As the number one workholding choice, the full range of vise accessories can help with setup reduction. Among these are carvable jawplates, quick positioning workstops, and chipshields. There are also accessories for locating the part edge and indicator spindle attachments with which to mount indicators for alignment of the part and to find the center of a tooling hole. Typically, work done per set up is short in actual time spent in the cut while long in the time spent planning. To eliminate some of this downtime, quick change jaws have been developed, which, in some cases can reduce changing jaw plates to just 5 percent of the previously required time.

Additionally, Kurt makes a mechanical and automatic Drawbar which can also help enhance productivity for Knee-Mills.

April 2005 - Helpful accessories make the clamping job easier

Many workholding gadgets have been developed by toolmakers to eliminate a particular workholding problem. Over the years, workholding manufacturers have developed products that make the operator’s job more pleasant. A list of the most useful accessories include:

1. Speed handles with multiple knobs for fast vise opening and closing.
2. Vise handles with adjustable arm lengths.
3. Vise handles with torque readings for sensitive and repeatable clamping.
4. Vise screw extensions for freedom to reach through machine guards.
5. Hydraulic intensifiers for hydraulic vise models which eliminate the need for electric pumps.
6. Air cylinders with multiple pistons which achieve effective clamping pressures using standard 100 psi shop air.
7. Step key sets to adapt vise keyways to those of the machine.
8. A complete array of different work stops.
9. Countless specialty jaw plates and parallel sets.
10. Coolant and chip shields which mount in close proximity to the cutting action.

March 2005 - Custom Fixturing. When And How Used (Part Four of a series)

Continuous production of high volume components may best be machined in a custom fixture. This will allow the highest density of parts in the machine and the locating of parts from points usually not accessible with a vise. Typically, these fixtures on vertical and horizontal machining centers are power clamped with elaborate spring-loaded pre-locators which keep parts in place until all can be clamped simultaneously. The fixture must be designed for thorough chip washing ease in order to present a clean fixture for reloading at the end of a machining cycle. Most clamps used for these applications are swing away, rotating type hydraulic clamps which are offered as standard products by many companies. The best designed fixtures typically do not have exposed plumbing so that cleaning is easy. These types of fixtures are usually expensive initially but ultimately provide the best solution. When in-house tool building is planned, the resulting tooling is dependent on the experience of the designer. In certain cases, the work piece designer may through simultaneous engineering, solve many future workholding problems during the early iterations to the part design. (click to see custom VMC and HMC examples)

Future For Workholding. As long as machines are needed to machine parts, vises and other types of workholders will be needed to position and hold materials while the machining operation takes place. Vise improvements and refinements will take place in the area of versatility, accuracy and speed of operation.

Automation of the workholding process offers the best payback when used in higher volume or continuous part production. At the early component design stage, consideration should be given to workholding using repeated robotic part clamping for part movement through several work sequences. For this reason, part designers need to consider their future workholding requirements while in the initial concept stages. (End of this series of articles)

February 2005 - Highest Workholding Density Tips (Part Three of a Series)

Highest workholding density requires double station vises equipped with special carvable jaws plates or carvable jaw blocks. When work pieces are small enough two parts can be clamped in each jaw set or four parts in each double station vise. This requires four workstops on each vise or the machining of part locating nests. Carving can be done using carvable jaw blocks made of ductile iron or aluminum for lighter operations. When selecting this type of vise, it is important to recognize significant differences in performance between vise brands. Most significant is the amount of moveable jaw lift under a given clamping pressure. The easiest way to compare is to use a dial indicator next to the work piece on top of the moveable jaw taking readings at different pressures. The best and most accurate vise is the one with the least amount of jaw lift.

The next highest workholding density can be achieved with cluster vises where multiple vises are machined into a single body. This type of workholding is generally available in less standard varieties but can be economically made to order. The advantage of cluster vises is that they remain in exactly the same relationship to each other compared to trying to align multiple vises in a workholding setup.

Highest workholding density is achieved when the movable vise component is a module that can be moved in small increments on a serrated base. The modularity of these systems allow the user to configure the equivalent of custom fixturing with standard “off-the shelf” components. Serrated workholding systems allows manipulation of all variables normally encountered in a high density setup. Stationary jaw blocks can be moved wherever needed and can be made of a large variety of materials to fit clamping requirements. This serrated system is especially suited for tombstone applications where three sides of a part need machining and the clamping components are relatively small. Vertical machining centers with pallet changers are also an excellent application for a serrated clamping system.

Coming March 2005... Custom Workholding Tips

January 2005 - Vise selection and their characteristics (Part Two of a Series)

Workholding selection for vertical and horizontal machining centers should be based on desired density, vise opening, clamp pressure needed and shape of the part. The stationary jaw of a pull type vise is cast integral with the vise body. It is a good selection when density and absolute minimum deflection is needed. Side mounting or end mounting is possible. Also, pull type vises can be aligned next to one another without spaces. The primary benefit of a pull type vise is that only a minimum amount of the clamp force actually exerts bending forces on the vise body so that a significant force actually backs up the stationary jaw. Pull type vises are made of ductile iron, work well on thin machine tables, and are relatively light in comparison to other types. They have hydraulic and air operating options. Also, the stationary jaw can be positioned toward the operator or facing the machine column. This allows positioning the vise screw where needed.

High density requires double station vises. These vises have two clamping stations, pushing the workpieces toward the stationary vise jaw block between them. This neutralizes the bending pressure against the center of the vise, allowing a relatively thin section for the stationary jaw, thereby saving valuable space. Double station vises feature a ductile iron body that dampens machine vibration, and is superior to other lighter materials. This is most notable when heavy metal removal rates are required.