A Historical Feat of Precision Machining

By Lloyd Graff

Ethamore Claar died at 55 near Pittsburgh. Among his possessions was a brass bell made on a National Acme screw machine at IMTS in 1971. Mr. Claar, known as Frank (the Ethamore came from his grandfather’s first name), worked his entire career as an engineer-draftsman for Kennametal, according to his niece Dorothy Miller who sold the bell to us for $15.02 on eBay.

This bell, which measures 2 1/4” high, was made on an Acme in a one part cycle with an elegant improvisation that somehow stuck the clangor into the housing.

I would love to hear from Acme aficionados on exactly how this was done and if they have recollections about the exhibit. I am offering the bell as a prize to the person who comments in the most interesting way about this intriguing engraved dinger.National Acme Screw Machine Anniversary bellDSC09959

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24 thoughts on “A Historical Feat of Precision Machining

  1. Rick Bafford

    I also have an Acme Bell, and the original wooden “packing crate” that the bells were put into at the tool show. My memory is a bit fuzzy, but to the best of my knowledge, these were made on a six spindle (probably a 1-5/8 or 2″) at the tool show. The clappers were made ahead of time and were magazine fed into the bar machine and swaged into place. I think the swaging took place in 4th position. There was some sort of contraption in 5th position (cutoff) that laid the bells into a track, so the bells came off the machine ringing. I used to have a copy of the machine layout, but have lost it over the years.

  2. Jim Harvey

    While I never worked with an ACME, I can only say that that tiny little bell along with “turners cubes”, balls inside balls, right angle drive rods and other small items that were either used for demonstrations or to actually train apprentices should rightfully be classified as National Treasures. The level of skill that was present in an ordinary machine shop in the 1940’s can’t even begin to be quantified. While we have 5 and 6 axis machining centers today that can produce parts that would have been virtually impossible “back in the day”, the knowledge of techniques to produce problematic pieces by hand has nearly vanished. Programming has taken the place of hands on experience which to me is a very sad thing indeed. That little bell is just a whisper of the past and the talent that men and women possessed. It is a part of a pas thistory that will likely never be repeated. It really deserves a prominent display.

  3. Steve Wenning

    Rick is right on the set-up. I am looking through all my stuff but can’t find the tooling layout. If I find it I will scan it and send it to you.(What e-mail adress should I send it to?) I didn’t go to that show but it was done at other Chicago Machine Tool Shows after 71. I have a bell but no shiping crate. I keep in in a little display of of things I have picked up from the past shows. The Acme also had a bar feeder on it. So it was making bells all the time. Acme also gave these out if you were going to buy a new machine. They had the process set-up in Cleveland for a long time into the 80’s. I bought my last Acme in 79 but went back and forth a lot to Cleveland until about 85. .

  4. Rick Bafford

    I’ll be glad to take a picture of the crate and the bottom of the bell, but I’m not sure where to upload pics. I’ll send them to Lloyd’s e-mail and see what happens.

  5. Dave Sibinski

    As a long time screw machine engineer for Roberts Automatic Products, now retired after 45-1/2 years of service. I remember standing in the long line at the IMTS show that year when National Acme had this demonstration part set up on a 1″RAN -6 Acme. The part came off the machine ready to ring. Others have described the set up in this way. Yes the clapper was machined in advance on a screw machine, and they were hopper fed with a vibratory bowl that was positioned on top of the machine. The track conveyed the clappers into the tooling zone with the ball end forward. The nest the the clapper was held in was a 1/2 round trough with a swaging area on it’s front face. This was in the 4th position from the end. This tool advanced the clapper into the drilled hole, and advanced enough forward to swag the brass around the ball end of the clapper, which held it in place, but yet allowed it to freely move as the bell was rung.
    In the 5th position, the part was held with the pickoff attachment, and the end of the handle was radiused with the form cut off tool to eliminate the nib.
    I actually have two of these bells in my posession.

  6. John Archibald

    It looks like enough people have sufficient memory to have de-mystified this fabrication technique. However, left to my own devices, I might have done things a little differently.

    With enough time and money to play with before the show it might have been possible to machine the bell and leave a short straight small diameter rod attached under the bell with a bulbous end at the bottom. The short straight rod would then be “rolled” or wire drawn with a special tool or two piece clamping die until it became longer and skinny enough to bend and flex like a brass wire.

    This wire with the bulbous end would act just like a free clapper and that’s what I would have tried. That way it could have been made from one piece. That would have gained a bit more attention at the show.


    John Archibald
    Instrument Maker
    Northfield, Minnesota

  7. lloyd

    I love your comment John Archibald. You took the blog and pushed it down the field. It is great t to the clapper issue.o reminisce about the clever Acmeites if 38 years ago, but you took it the next step. How about a few more right brain approaches

  8. Peter

    I am working to get you an answer on this.

    I’m not sure I would call it Historical or Precision. It used form or brazed tools and brass is very soft as you know. The clapper was inserted into the Bell after it came off the machine.

    I would suggest you send this to the Precision Machining magazine people also. They do a history piece every month.

  9. Peter Frow

    Hi Lloyd,

    Here’s how it’s done:

    1. The body of the bell is formed in the normal way using form tools and spade drills.
    2. One of the drills forms a socket with a lip at the point where the handle meets the skirt of the bell.
    3. The clapper is made on a separate machine and has a ball formed at its upper end.
    4. These clappers are then magazine fed into a combination insertion/swaging tool at the second last position on the multi.
    5. This tool both inserts the ball into the socket and swages the lip over to keep the ball captive.
    6. The bell complete with clapper is parted off.

    I can’t claim credit for this however except perhaps the magazine part as I saw a similar bell being made at an exhibition on a little Colchester capstan some years ago. Here the clapper was inserted by hand into the swaging tool.
    I in fact have one of the bells in my living room.

    Yours sincerely

    Peter Frow
    FAS Machine Tools
    South Africa

  10. Tom Dierks

    I was working the 1970 IMTS show (not 1971) for Sundstrand Machine Tool (also long gone). This was the last of the 5 year cycle IMTS shows. After 1970 they became a 2 year cycle. This show was held at the Chicago Amphitheater / Stock Yards with no air conditioning and ran for two weeks through the weekend. Since I was there the whole time my goal was to obtain an Acme bell, but Acme only ran for a few minutes avery hour or so. Seems like every time I got a break they were either not running or the line was 60-80 people long. To say the least I have coveted the bell ever since. As a green NC applications engineer i didnt know enough about how Acmes worked to give any info here except that it dropped off complete, still pretty amazing.

  11. Dan Murphy

    We ran a similar demo if my memory serves me, back in 1988 and ’90 at IMTS. My understanding was that it was an old demo that was resurrected to attract some attention. And also so our product manager for Harrison could visit with an chum from the UK.

    The bell was run on a Harrison AA tool room lathe that was fitted with a turret and I think a cross slide which effectively turned it into a hand screw. At any rate, the fellow that originally had run the demo was retired from Harrison and was in his early 70’s. They coaxed him out of retirement to come to Chicago and run the demo by offering to pay all expenses for him and his bride.

    I ran the clappers beforhand on a Tsugami CNC Swiss. There was a tool on the turret of the Harrison that would insert the clapper and swage the hole in the bell, capturing the clapper.

    The remarkable thing was that old Harvey, the retired guy from Harrison in the UK, stood at the machine cranking out bells with hardly a break. Harvey was old, all of about five foot nothing and as skinny as a rail. But he stood there in his white apron cranking out bell after bell as sweat rolled down his face. He seemed to have an unlimited supply of energy for an old guy. With his british accent, lively sense of humor, and the flair of PT Barnum, he always had a crowd.

    I also remember that this demo made mountains of chips. On the first day of the show, Harvey struck a deal with one of the cleaning people at McCormick Place. In exchange for a couple of bells and all of the chips, this guy would clean out the lathe every night. Every morning Harvey would return to a lathe that was so clean you’d swear it had never been run.

    The bell was roll stamped “Turned True and Tuneful by Harrison” around the OD.

    While cranking bells out on an Acme is cool, doing them by hand every day for the entire show was no small feat either. Especially for a guy in his 70’s.

  12. Jeff Kovalenko

    Dear Mr. Graff:
    I was at that show, although I was underage.  I have a picture, which I will try to dig up from the show which has several people who worked the show.  If I find it, I will email it to you with names of all the people that I can recall.
    Included were Tom Kovalenko, Ray Maurer, Ken Konet, Gary Henninge, possibly Harold Loehn and some others, maybe Don Collier?  They wore matching sportcoats which were about the same color worn by Don Meredith, Howard Cosell and Frank Gifford during the early days of Monday night football, kind of mustard colored.
    My dad told me that they also took a photo of me.  I was asleep on a trade show type couch with the machine in the background.  Somebody suggested to my dad they ought to use that photo promoting how quiet the Acme was.
    The bell was wildly popular.  People rang them in the aisles during the show which caused the AMT to create a rule against noise making premiums or maybe the rule is McCormick Place’s. 
    The idea was not completely original.  Somebody saw bells made at a tool show in Japan.  In Japan there was a staff of pretty girls that inserted the clapper. 
    National Acme however installed the clapper and ‘swaged’ it in on the machine.  I remember the bell was in celebration of National Acme’s 75th Anniversary and had some items rolled on the bell including a diamond in recognition of same.
    I have no specific knowledge of how the part was made other than it was out of brass bar stock, and that the clappers were loaded into a magazine.  As I think on this further, I think that Acme might have has a second machine making the clappers.  If so, I think this would have been a 7/16 RA-6.
    My guess would be that made it on an 1-1/4″ RB-8 and had a special attachment to insert the clapper, and that they picked off.
    I am sure there are people around that know more details about the Acme bell, but I wanted to share my recollections.
    Sincerely, Jeff

  13. ron clines

    my did this bring back some great memories. i work on acmes for about 35 years,and loved it . they are the best machines going or gone. we did some amazing things on those machines.the. i would have loved to lay this job out. thank again

  14. Noah

    Hey everybody. I promise we will put up a new photo shortly of the inside of the bell. We bought it on Ebay and it has been sent to us.

    Sit tight and thanks so much for commenting!

    Noah Graff

  15. Bob Ducanis

    One of our guys had the bell from the 1970 show on his desk for a number of years.

    I found the layout for the part printed by NAMCO for the show.

    The clapper was produced ahead of time and fed down a track to the Acme that was machining the bell-body from brass barstock. According to the layout, the machine was a 1-3/8″ AG-6 bar machine. Cycle time to machine body, assemble clapper in the 4th position, and cut-off was a total of 4.7 seconds. RPM was listed at 1928 RPM and SFM on OD was listed at 630 ft./minute.

    The notations for the 4th postion were “POSITION CLAPPER”…..”SPIN TO RETAIN ASSEMBLED CLAPPER”

  16. Bill Prion

    I remember hearing stories about the Acme bell during the time I was ‘negotiating’ to buy a machine from Acme. We purchased 2 model AG machines and I was in Cleveland discussing problems we were having with them. The year was 1984.

    They had discontinued that model and I was shown a 1-3/8 AG6 that had been their ‘show machine’ and was said to have produced the bell. It was painted yellow and blue and was a spindle stopping machine with electric clutches.

    The machine had been cannibalized for parts and was planned to be destroyed but I convinced Ralph Spresser of National Acme to sell it to me. The machine had no serial number and was sold as a group of parts instead of a whole machine for liability reasons.

    We replaced its missing parts and addressed several small design issues and it has performed extremely well for us all these years. The 1-3/8 and 1-5/8 AG Acmes had several small issues but their overall design is immensely superior to other cam screw machines. It was the ideal choice to showcase a complex setup like that of the famous Acme bell.

  17. Miguel Berrios

    I also have two bell one from the 70’s and one from late 80’s and I know how they were made. I be around Acme for 40 yrs and still working with them.

  18. Tom Decker

    I also have one of the bells and the original wooden crate from the 1970 tool show, which I got at National Acme in 1974. The few that were left at that time were passed out to attendees of their training programs, which in themselves were a very good deal. As I recall, it cost $100 for a week at the plant along with over $100 worth of books.

    I spent quite a number of years on Acmes and still have an operable 3/4″ R6 from the early to mid thirties in my collection of more or less antique machine tools.

  19. Alison Wood

    I just found one of these cute little ACME bells left behind in the storage cabinet of a house we recently purchased. The thing that amazes me is the loudness of the ring of this little guy! It’s neat to read about its history and hear from others who also have one.

  20. Richard Stryker

    My dad, Dick Stryker, was I believe US sales rep for Harrison machine tools in the late 70s. Watching that cutting-edge CNC machine tool churn those out at the Pittsburgh show was pivotal to my becoming an engineer years later. We had one of those bells, marked as Mr. Murphy described above, but it’s been lost to both Dad and Mom passing, and the breakup of their estate. In fact, I was hoping to find one on the internet to put on my Springer Spaniel in the field, as a tribute to and remembrance of my dad.

  21. Wes

    I’ve heard about this story for years from the guy who works in our tool crib. Wow, great to hear all these stories about it and how it was done.


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