Had this very interesting discussion with Mark Parish yesterday when talking about variable pitch milling cutters. He told me this story of British soldiers breaking stride when crossing a bridge to prevent resonant vibrations that legend has it caused a massive bridge failure in 1831. I found this great article on the subject that explains how the rhythmic marching matched the vibrational frequency of the bridge. However this article leaves out a very important point. The vibration described was self excited and regenerative. It started when the first row of soldiers mounted the bridge. Each succeeding row increased the force applied to the bridge and amplified the vibration until enough rows of soldiers generated enough force that it reached its failure point. In milling, regenerative chatter (AKA regeneration of waviness) leads to tool failure.
Here is a tip if you are giving a presentation online. Use a separate PC or tablet from the one you are using and log in with it as a guest over wifi. This second screen will show what your viewers are seeing, accounting for any lag in the slide advances. Also a good idea to turn off any slide transition animations to speed things up online.
What does it mean to have tap-testing and analysis capability resident on the CNC control and available at the point of use?
It changes everything.
Anyone can learn to tap-test milling tools in less than 30 minutes of online training. They can then tap-test a tool and generate a Dashboard in less the one minute.
You don't have to decide what milling tools are "tap-test worthy". You can test and optimize them all.
With the Dashboard, not only will you find the best speeds, feeds and depths of cut for maximum metal removal, but also what parameters will give you the best surface finish and accuracy.
Are you a job shop? Throw a tool together from the crib, tap test and generate a Dashboard. Have a tool from one vendor, and extension from another and toolholder from a third? Special cutter? No problem. Tap-test and generate a Dashboard. Make the part right first time
Imagine if you had ten vendors bringing in ten tools to evaluate for an application. How long would those trial & error tool tests take? A week? two weeks? Or, you could tap-test all ten and determine a winner in less than an hour.
And, yes, you can share the TV remote size kit and software between multiple machines.
We have technology to track our schedules and remind us of appointment times. We have GPS systems that estimate arrival times with amazing accuracy. We can see what the weather will be enroute and accommodate accordingly. We can contact people by phone, voicemail email, text, Linkedin, Facebook and Twitter.
YET, I HAVE NOT BEEN TO A MEETING IN MEMORY THAT DIDN'T START LATE AND OR HAD A KEY ATTENDEE THAT WAS LATE AND NO NOTICE WAS GIVEN.
When you are late for a meeting with me and keep me waiting with no notice, you are telling me my time is not as important as your's. WHEN DID THIS BECOME OK?
Another thing, how many times have you left a meeting and the chairs are strewn around the room, crap left on the whiteboards with food, drinks and garbage left on the table. These are the same people that probably post the meme below. WHEN DID THIS BECOME OK?
Try this next time. Be on time, even early. When the meeting is over, especially if you are a guest, put your chair back, wipe down the boards and throw away your own garbage. Thank everyone who setup the meeting (including those who brought the food).
You never know who is taking notice.
This is a Latin phrase that means “All Things Being Equal”.
Humans have an amazing capacity to adapt, modify, tweak and re-invent when faced with a challenge. The image below is of the staggered tire diameters of a race car. This form of racing is on small oval tracks where the car is almost always turning left. Someone figured out that staggering the tire diameters helps make the car turn left on its own. Of course, you wouldn’t do this on a drag car going in straight line.
In the absence of long straightaways, tire stagger works.
In milling, we put a lot of emphasis on “Ceteris Paribus” by making tool assemblies concentric and balanced, yet we introduce unequal elements by varying the pitch or helix angle. Why? Because faced with chatter and not being able to measure the system’s frequency someone tried modifying the endmill and it worked in their machine with the toolholder they were using.
In the absence of dynamic testing, teeth stagger works.
Does this mean if we tap-test a proportionally spaced tool we can find performance equal or greater than the variable pitch/helix? Again, “Ceteris Paribus”. If the same beneficial advanced substrates, edge prep, coatings, post-coating polish and corner breaks/radii were applied, the answer would be yes.
Thanks to Peter Haley and Brian Stall at Gosiger Inc for the successful test of our new tap-testing hardware and software for the Okuma OSP control. Hammer and accelerometer attaches to USB. Tap tool and generate interactive Dashboard showing stable speeds, feeds and cutting depths in less than 60 seconds right on the control’s screen.
The endmill of the left has proportionally spaced teeth, the one on the right the pitch of the teeth are varied. On the variable pitch tool, tooth #1 and tooth #3 are in the cut much longer than #2 and #4. They will, therefore, wear out faster. Also, the average chip thickness for tooth #1 and tooth #3 will be larger than those of #2 and #4 so we may need to dial back the recommended feed rate to compensate. You may notice this when comparing the speed and feed charts of proportionally and variably spaced endmills.
I saw this 1945 catalog for sale on eBay and it brought back a memory. While working for Lou Wiener at Rutland Tool & Supply in the early 80's, he asked me to take care of this older gentleman who was visiting the offices. All he wanted to do was look through our racks of vendor catalogs that stretched along the wall in a long hallway. He collected them in a large shopping bag with handles. This gentleman was named Carl Marshall. In 1937, he and his brother Mack founded Marshall Tool & Supply in Los Angeles to distribute tooling to the exploding aircraft industry in Los Angeles. On the other side the country around the same time, Sid Jacobson started a company to serve the large aircraft and other markets in New York. Years later he acquired Manhattan Supply Company (now MSC), but the parent company remained named Sid Tool. The connection was that Mr. Weiner started selling tools out of the trunk of his car in the 50's, tools he bought from Mr. Marshall and Mr. Jacobson. For the next few years, I would walk the floor of WESTEC with the retired Mr. Marshall as he collected catalogs in his shopping bag, everyone oblivious to the pioneer in their presence. All three men were hugely successful and were very kind and gracious to me when I was just getting started.
Sharing information about high performance milling technologies, the result of 30 years of research.