Announcement

Collapse
No announcement yet.

'Fun' (frustration) with number stamping

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 'Fun' (frustration) with number stamping

    After spending months on a project that went exceedingly well, I met my Waterloo stamping numbers, making a fine project and a critical component into an amateurish looking debacle.

    It wasn’t because I didn’t try. I built a stamp holder/guide as designed by George Thomas, which was held in a custom built, incredibly rigid jig attached to my lathe cross slide, with the slide position indicated by a DRO. Also used was an indexing jig with 360 one degree positive detents for the lathe spindle. Rigidity, repeatability and proper alignment were the objectives of my set up.

    Unfortunately, I immediately ran afoul of a couple of brothers, the Young Bros. The set of stamps they had produced, and I had unwittingly purchased, left a lot to be desired. Most stamps could not be inserted in my stamp holder due to burrs along their shafts. Some stamps were bent into a banana shaped curve, preventing insertion and some had ‘bumps’ of garbage adhered to the shaft surfaces.

    Once the stamp shafts were dressed and straightened, the stamping began. It was immediately found the stamped character position varied in relation to the stamp shafts so that even with my stamping jig doing fine duty, the results were somewhat putrid. For use of one particular number, I was forced to move my lathe carriage (stamp holder) to compensate for a gross vertical offset.

    I’ve seen some exemplary examples of stamped numbering on this site over the years. How do you do it? Are there better quality stamp sets available? If so, where? Did I just get the set of stamps made at quitting time, or is this par for the course? Do people develop an X-Y coordinate offset correction chart for each stamp character? If you do produce an error chart for each character, have you attempted to surface grind selected stamp shaft surfaces to achieve character position uniformity, relative to shaft position? Tips, tricks, etc????

  • #2
    I have had to take several of my stencils to the belt sander and correct the problem you noted. I have not noticed any bent or crooked shafts. There are higher quality sets.

    Comment


    • #3
      If the lettering is "that" critical I'd just send the job out and have it engraved...
      Keith
      __________________________
      Just one project too many--that's what finally got him...

      Comment


      • #4
        Write down exactly what you want to stamp so you have a visual reference. Check spelling. I lay down a piece of masking tape so the upper edge is where I want the bottom of the letters. Figure out where you will start and end. Start at the end of the line and go backwards so you can see where you've been and space the next letter accordingly. Bring the bottom of the letter to the masking tape - you can feel when it's there and the letters will be in a straight line. Stamp your letters, remove the tape. Done!
        Engraving always looks better than the best stamp job, but sometimes stamping is good enough.
        Last edited by Toolguy; 08-22-2012, 11:13 PM.
        Kansas City area

        Comment


        • #5
          I've had the same problems having to dress the shanks before they would fit evenly. Then I also notice the variation in the position of the numbers. My stamping has also been on a curved surface (dial) so there's an uneven depth. However it also becomes clear that the faces are not all square with the shank since some will impress first on the left and others on the right.

          However, I've noticed that when first stamped they really look bad, but by the time the raised metal is dressed back down and the surface polished up again it's not nearly as bad. You can still make out flying or drooping characters if you look, but it doesn't just stand out like a sore thumb. Have you redressed by this point?

          There was also a discussion some years back about what manufacturers might be better and somewhere I've got some names noted down if I can ever find the list.
          .
          "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

          Comment


          • #6
            Often discussed.

            http://www.google.com/#hl=en&sclient...=1215&bih=1021

            David Merrill

            Comment


            • #7
              If you want to use simple tools here's is an article I wrote (Making Graduated Collars) on the subject a number of years ago and it can downloaded at the New England Model Engineering Society's web page.

              It's the third link on the list...
              http://neme-s.org/images/PDF_Files/p...nload_page.htm

              Steve Wells also has this article for download...
              http://www.wswells.com/projects/projects_index.html

              It's the seventh one on the list.

              Here's an example...


              Last edited by Mike Burdick; 08-23-2012, 10:18 AM.

              Comment


              • #8
                I have three older Young Bros stamp sets (machine made), none with bent or otherwise obstructed shafts. They all vary some as far as the location of the character relative to the shaft cross-section. I usally 'paint' a strip of layout blue or marker and scribe a fine line at the base of the text field. Using good light, and getting down to the level of the work I can get things lined up well. The absolute best results I see are using the above technique and a hydraulic press to imprint the character. The press gives extremely consistant depth and definition, but is slow.
                Southwest Utah

                Comment


                • #9
                  I think that stamps with flat bottom/number-letter faces on a round surface are not ideal - and its gets worse as the stamps get bigger and/or the diameter of the round part to be numbered gets smaller.

                  It seems to be an ideal CNC job which will do the lines as well.

                  If it were me I'd shop around for a good engraving service that can meet these criteria.

                  With the right jig/fixture it is quite possible to use a pantograph engraver and engrave such things as lathe/machine dials and even the barrels of a micrometer.

                  Its over 50 years since I got out of the engraving section - thankfully - but it did very nice work inserting the red or black "wax" which hi-lighted the engraving. We did some very nice work with "Traffolyte"as well:

                  http://www.google.com.au/#hl=en&gs_n...w=1920&bih=851

                  http://www.google.com.au/search?q=tr...w=1920&bih=851

                  After that little episode I got changed to the big Swiss "Deckel" pantograph that was maneouvered by hand - with the guide-drive (kept in constant contact with the "pattern"/"master" - as with a router - bar kept in the shoulder like a rifle and all the while in a belt upper body harness. It was very good work too but I was not sorry to see the end of it - and straight into a "Ward"6 and larger (hand-operated too) turret/capstan lathes and then onto hydraulic copying lathes.

                  Believe it or not, these were part of the "Milling" section which also included shapers and slotters.

                  In the end, I sure did remember "engraving" - and pretty well still do.

                  Comment


                  • #10
                    I've never thought you can assume the position of the digit or letter is consistent relative to the shank.

                    My usual technique is to apply some masking tape to the area being stamped, then you can push the stamp into the masking tape and it makes an impresison/indent which you can inspect. If it's not in the right spot or is at the wrong angle you just wipe the tap with your finger and it resets itself.

                    For each new letter you do this and check that the 'imprint' is lined up with the previous stamps before you proceed.

                    Once you've happy you've got the imprint looking right you put the stamp back in it and give it a whack.

                    Typography and letter spacing is best done by eye like this in my opinion, I think it's more art than science.

                    Cheers,
                    Rich

                    Comment


                    • #11
                      I am working on a project that requires a large number of graduated and numbered dials, collars and plates. I'd like to be able to say that there is a method of using number stamps that will give you as good results as proper engraving, but that isn't really the case, for me anyway. But you can get an acceptable result with a lot of care. Mike Burdick's PDF above, shows some really good numbering. I don't think my examples are quite up to that standard but anyway, this may give you some ideas.

                      1) Problems with stamps. I bought what I expected to be good quality number stamps. Like many others I found that they were not quite as good as I had hoped. The square bodies vary a bit in size and the numbers are not in a consistent position with respect to the shanks. The best method for fixing this I got from a friend in Belgium, which is to use a surface grinder to get all the numbers in the same position with respect to a pair of shank datum faces. Then use a Geo Thomas type jig to guide the stamps. This is an ideal approach, but needs a surface grinder and some means of measuring the number offsets very accurately indeed. The human eye is very sensitive to misalignment, so you need to work to very close limits to fix the stamps. I don't have a surface grinder so I had to use a different method. I made up some test pieces where all the numbers were stamped using a guide to align the edges of the stamps and then measured the offsets of the numbers in X and Y. Write these down and keep them with the stamps. Then when you use the stamps with a jig, Dial in the required opposite +- offsets number by number to bring the stamps into line. Yes - PIA.

                      2) Graduation. Most of my dials need graduating and numbering, and I think that this is the typical case. So although the OP doesn't mention it I think it logically belongs here. I use two basic methods of graduation. When possible I use my lathe with a detent device on a gear train and a graduating tool in the toolpost. This is quick and easy to use. Some cases are easier with a rotary table on the mill. I have made a tool which holds my graduating tool in a quick change toolpost and bolts to a tee slot on the side of my mill. This slot was intended to hold dial gauges and be used with slip gauges for setting the top Y slide. This is nice and rigid and allows positioning with the mill DRO and rotab.
                      .
                      Graduation then just involves indexing around and remembering to mark correct lengths for 1s, 5s and 10s.

                      3) Numbering jig I use a Geo Thomas style holder for stamps and this can clamp to the same arm. It is necessary to locate the numbers in the correct positions with respect to the graduations. This needs angular and linear offsets. I find the best way to do this is with a scrap test piece, since it varies with the size of the part, number size etc. To establish the location I use an accurately machined pointer which fits the number jig hole tightly. This allows you to set the position for the right and left hand (assuming two digit numbering) accurately. Then apply the required offsets. In the photo below, you can see that the angular offset is 2 degrees, and I have written this on the jig so I don't forget. You can also see that I have written all the required numbers on the part so I don't make silly mistakes. This is very important for a part like the one shown which has complicated numbering and has several days work invested in it. Don't ask me why i think this is important


                      4) Stamping You need to hit some numbers harder than others to get the same depth of impression. An 8 for example, needs to be hit harder than a 1. Fortunately if you use a good jig for the stamps, you can get away with a second tap. The cumulative effect of many impacts to your part as you go around it can cause it to move. It is a good idea to check alignment periodically so that the last numbers stanped will look in alignment with the first. Again, don't ask how I discovered this little problem.
                      Don't hit the stamps too hard. That will displace too much metal in the general area and will show when the part is finished.

                      5) Finishing off The stamping will raise the metal around the numbers. The appearance can be improved by very lightly filing the surface in the lathe, then finishing with very fine wet and dry. Don't use abrasives instead of a file, it will round everything off and spoil it.


                      Hope that gives you some ideas.
                      Last edited by willmac; 08-23-2012, 07:36 AM.
                      Bill

                      Comment


                      • #12
                        I have used the “slide the stamp against the masking tape” trick before and it works well. At my last shop though, we ground a steep angle on one side of the stamp, down to, and just barely touching, the bottom of the letter or number. This way, you could line up the bottom edge of the number exactly with your layout line. With a little head tilting, you could see the letter or number form to judge left to right spacing.

                        We did the grinding on a surface grinder and took pains to ensure the grind was square to the letter form. You could do it on a bench grinder but a jig would be helpful.

                        The drawing can explain it better than my words.

                        George
                        Traverse City, MI

                        Comment


                        • #13
                          George- Great Tip !

                          Bill- outstanding perspective and approach to solve a normally aggravating problem- Thank you

                          We did some stamping on our dies years back, so I don't remember product names, but our stamps were very accurate and had
                          a half round notch in the shank,on the bottom side and about one inch from the letter surface.
                          The notch made sure the numbers ( especially "4" !) were properly oriented and also fit in a hand piece for stamping multiple letters at the same time. The stamps were all the same height, but did vary in width ( I,M,W.) The hand piece had a registration bar (key) that located all the stamps for equal impressions and did so perfectly.
                          So , YES, there are good stamps available.
                          Rich
                          Green Bay, WI

                          Comment


                          • #14
                            Stamping on that project that you have worked on for weeks and the results are disappointing ---- aaarg!

                            Lane showed me his solution, and I immediately thought it addressed most of the inherent problems with getting a good result stamping - and, its available to all of us, its in Vintage press "Metalworking Book 3" under the title "A Precision Metal Stamper" by Glenn Wilson. (Glenn did some good stuff!)

                            Heres a pic of it



                            Designed to fit into an R-8 spindle on the mill giving the benefit of using the X & Y tables to control the spacing. Having a spring loaded 'piston' to drive the stamp you can use the spindle crank handle to control the force of the imprint by raising or lowering the distance the stamp moves when you pull the trigger. With a bit of practice you can get quite good results - tho there is always a 'flyer' sometimes.

                            FWIW: I have HF stamps and have very good luck with them - touched 2-3 briefly on the belt sander....
                            Last edited by Bill Pace; 08-23-2012, 09:24 AM.
                            If everything seems to be going well, you have obviously overlooked something........

                            Comment


                            • #15
                              I have used antique stamps for many years,many of which are hand cut,and have all manner of problems. Some are a bit rotated with respect to the shaft body,off center,etc.. But,their characters are nicer than you can buy today.

                              SOME USE DYMO TAPE to slide the stamps up to. It is better than masking tape to not "dent" when the character is pressed against it.

                              I learned a tip from master gun engraver Lynton McKenzie(now deceased): Scribe a line in the metal to be stamped. Use only SHARP edged stamps,not worn out ones with rounded edges that are inconsistent. Cock the stamp a bit towards you above the scribe line,and draw it down towards the line till you feel it click into the scribe mark. Without moving the stamp,make it vertical and strike it. Then,cock the stamp a little towards each of the "4 corners" of the character,and strike it on each corner. Sand off the scribe line afterwards,and also sand to remove the pooched up metal around the characters. Nothing looks worse than raised metal around your stampings,but it is often seen today on finished products due to lack of artistic training,or carelessness and penny pinching of manufacturers,especially on guns after they have been blued,and then you don't want to sand away the bluing.

                              Rio Grande now sells sets of nice letters with serifs. Some are inclined,if I recall. I have spent DECADES finding old stamps with nice letters with serifs in flea markets. My oldest set,which must be nearly 18th.C.,were cut into crude steel bar stock with 4 straight side,and 1 rounded side from being crudely rolled. BUT,the letters are true Roman letters with thick and thin elements of the letters,unlike any of my other stamp sets.

                              An alternative,call Buckeye Engraving
                              co. and get them to make you a name stamp. Several years ago,a G.WILSON stamp was $75.00. They will use any type font you specify,any height. I'm sure they cost more now,but if you do high class work,you need high class stamping with serifs to finish it.

                              I,too,have resorted to grinding away metal to be able to see the actual edge of the letter. These crappy stamps they sell today have a HUGE amount of metal around the letters. It is ridiculous trying to tell where the letter is located when you are trying to use them. I just DO NOT use those new stamps. They don't have serifs anyway. Be careful to not grind away at too steep an angle,or you might weaken your letter,and find a piece of the letter popping off.
                              Last edited by gwilson; 08-23-2012, 09:49 AM.

                              Comment

                              Working...
                              X