Volume 8, No 4 - April, 2003

Statement of Purpose

Regular Meeting

Collier Library, 6200 Pinemont, Houston, Texas, March 8, 2003, 1:00 pm. Tom Moore, President, presiding. There were 33 persons present.  Five of them were visitors:  Steven Clay-machinist, Gary Shotson-machine designer, Nolan Cecil, Harry Trawling,  and Andy Catrel.
 

The casting group will have an event at Zube Park in two weeks.

Business Meeting

Minutes are sent via email or regular mail to club members.

Presentation

Our presenters were Doug Adams and Jim Dotson, speaking on Moglice, a  low friction material used to repair or make machine travel surfaces. It can be cast, molded, or pumped. It was developed and is manufactured in Germany. It can repair machine ways, half-nuts, ball screws and other uses. It is based on a two-part resin and various secret additives. It is expensive but will salvage machines that no other methods can. Mr. Dotson is with RGB Industries, Inc. of Pearland, TX. They brought examples, provided literature and distributed a CD disc to each person.

The approximate percentage ingredients of Moglice are: epoxy resin 40-80, molybdenum disulphide 15-30, graphite: 10-15, aluminum: 5-10, copper: 5-10, alumosilicate: 8-15.  Our club's Joe Williams found the Moglice patent on the web at United States Patent 4,329,238

.Show and Tell

 Metal Casting SIG

The Metal Casting SIG reviewed the plans for the casting workshop to be held on March 22 at Zube Park. The molding bench is in place and Ed Gladkowski is making match plates for the railroad track frogs to be cast at the workshop.
by Dennis Cranston
 

Computer Numerical Control SIG

No activity this Month.

Featured Article

Steel Hand Stamping
by Dick Kostelnicek - HMSC Member

Producing a good looking alphameric stamping on a metal surface is not difficult if you keep four points in mind. First, ensure that all letter and number punch dies in your set have an orientation or witness mark so that it is difficult to accidentally set a character upside down. Second, use a massive backup or reaction plate under the work together with a vertical stop guide to aid in aligning each punch before it is struck. Third, make the stamping in two passes; a light strike of all letters, followed by a  heavy final blow. Forth, enhance the overall appearance by filing-away or sanding-off the upset metal surrounding each character. Then, apply a contrast filler into the stamped impressions.

Figure one shows a typical set of 1/4 in. high letter stamping punch dies. Most sets have a witness mark scribed across the shank near the end struck by a hammer. By facing this mark toward you, the letter will be right-side-up. Don't attempt to determine the proper character orientation by flipping the punch and observing the die end. The character will be upside down and backwards. Flipping it in both your hand as well as in your mind is not an entirely reliable process. The factory witness marks on my old Craftsman stamp set, shown in Fig. 1, were just light scratches. I had to feel the mark with my finger nail, as my sense of touch and eye sight were not sufficient to orient a punch. As shown in Fig. 2,  I ground in a deep wide notch in the punches with an abrasive air driven cut-off wheel. The punches were held in a temporary wooden tray as the abrasive wheel was passed over all punches. The resulting grove, seen in Fig.3, can easily be easily felt as I hold each punch with my fingers.

If you try to hold a punch die between just two fingers, you will not be able to line-up nor adequately space the letters unless your are well practiced in metal stamping. Furthermore, there is a good chance that the punch die will fly out of your grip as it is struck with a hammer. I use a massive steel backup plate under the work being stamped. This plate absorbs the shock, acting as a backup to the hammer strike. Caution! Don't try to stamp a light weight work piece using just a wooden bench top for support. The punch die will surly fly out of your hand when struck. The wood table acts like a spring reflecting the energy from the blow right back at you. I use a 8 x 8 x 1 in. steel plate under the work, as shown in Fig. 4, to absorb and deaden the hammer blow.

Fig, 4 also shows how I keep the line of characters straight. Each punch die is held against a vertical back support with a shim that keeps the character's distance from the work's edge constant. Prior to striking, the die is set vertical with the aid a small metal tri-square. Fig. 5 shows my thumb is pressed against the punch die, while the remaining fingers of the same hand are squeezed against the rear of the vertical support. The die, therefore, is supported mostly by the fixture rather than by my fingers. The spacing, or kerning, of the letters is accomplished by sighting along the slant face of the punch die's end near the work and moving it over just until the previously struck letter becomes entirely visible.

Now, I don't like to make a stamping error on a work piece that I have spent many hours machining. Therefore, I first stamp the entire group of letters with a light hammer blow. Then I come back resetting each punch die by feeling-it-into the previous light impression, and then strike it with a single heavy blow. Figure 6 shows five letters in the word STAMP. The two characters at the right have undergone an initial light strike. The three at the left have had their final heavy blow. By making two passes, you have the opportunity to correct both letter inversions and spelling errors. You can stamp right over the first impressions with your corrections. In the upper part of Fig. 7, the letter "A" was initially set upside down. After correcting the orientation, and taking the final heavy blow, the impression is nearly fully corrected. This would have been impossible with a single heavy first strike. As will be seen shortly, the upset metal around the upside-down A's impression will be filed away, thereby, removing all traces of the inverted letter mistake.

Finally, the stamping's appearance can be noticeably improved by leveling the surface surrounding the imptession. The final hammer blow displaces or upsets the metal from the cavity left by the die to the surface around the letter. The volume of metal does not change. It is just displaced. This displacement makes the metal's surface bumpy around each letter, thereby, detracting from the crispness of the letters and optical flatness of the metal's surface.  By filing or sanding the metal's surface flat, a great improvement in appearance is obtained. See the stamping at the left in Fig. 8, which originally included the inverted letter "A".

A further enhancement can be obtained by filling the impression with a contrasting color. At the right in Fig. 8, black shoe polish was rubbed into the stamping. This technique is not permanent, especially in the presence of solvents of wax. However, it is fast and dramatic. I also use this technique to freshen the graticule lines on engraved steel rules and the engravings on graduated collars attached to machine feed screws. Fig. 9 shows a permanent method of creating contrast on steel stampings. Gun blueing, available at most sporting goods stores, is applied with a cotton swab to the impression. Then, 200 grit emery abrasive paper is used to rub-away the blueing from the work surface. The result; deep dark letter impressions surrounded by a shiny flat metal surface as can be seen in Fig. 10.

Cleaning up the excess blueing and leveling the bumpy surface can be accomplished simultaneously by inverting the workpiece and rubbing it on a sheet of 200 grit emery paper. Back the paper by a flat plate and rub in a figure-8 motion till the surface surrounding each impression is flat. Use a light mineral oil lubricant such as kerosene or WD-40 to help extend the life of the enery paper and float away the swarf.

Bon Stamping and don't forget to put on eye protection.

The next meeting will be held on Saturday April 12, 2003 at the Collier Library 6200 Pinemont, Houston, TX at 1:00 p.m. Bring along a work in progress to show. Visit Our Web Site homemetalshopclub.org

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