R8 or ISO
At a car show the quickest way to start a fist fight is to start an argument about if Ford or Chevy is a “better” make of car.
At a Machinist convention, the quickest way is to start an argument is about Hardinge or Monarch lathes.
And here, which taper is “better” R8 or ISO 30.
“Better” is a loose term, ambiguous at best. Each has advantages and disadvantages.
I sell both, I have both, I like both.
2 complete sets of tooling, 2 of everything.
Why? Because each has its place.
R8 works better on custom setups, one off operations, on my old mill I do mostly custom mill modifications, each setup is special. The work is always unique and the tooling varies quite a bit. R8 provides a lot of flexibility in the setup. Collets are quick and easy, you can put a drill bit in a collet and get good rigidity (for example), and then switch over to a fly cutter while using the same collet (both 3/4”). The work is custom, it is ok it takes few minutes to change over and re-zero.
On my production mill, ISO wins, I know exactly what I’m making each time. I do not re-zero during the entire production run of 8 hours and 48 tool changes. Changes take about 1 minute (or less) and repeatability is second to none. The tooling cost more, but I save the time and get more parts produced.
Purpose; is what it all comes down to. What is the purpose?
Insofar as which is more rigid? ISO wins hands down in my book. The contact area of the taper is what maters, ISO 30 has 2-3 times the contact of the R8. The rear shank of the R8 doesn’t matter as there is a few thou gap for clearance in there. In a perfect world is will not even be touching on the sides up near the top. It is touches equally (ie perfect fit) you run the risk of the collet getting stuck in the spindle after operation because of heat expansion. That will only happen once in every shop I’ve seen, they will make it so the collet comes out.
Taping it with a wrench is not the top of the collet binding, is overcoming the taper/compression lock. Beating it with a sledge hammer is heat bind. (been there...once).
Back to the R8, if it touches only on one side at the top, (not sure how this will happen) the end mill will wobble.
Often it comes down to the creation, the origin of a product that defines its purpose.
ISO stands for:
Industry
Standards
Organization
And is made up of bunches of people from each field of expertise and they give up time (for free) to make the world a better place for manufacturing and consumers. Then they publish those standards. You cannot copyright or patent a “standard”, but you can produce it without any royalty charge.
Basically, these masters in a field of expertise give their time for free (often they pay hotel expenses and flights and out of pocket by themselves), for the honor and privilege to determine how the “world” should do something. It is done out of respect for the industry. If you are on an ISO team you ARE the best of the best.
R8 is NOT an ISO standard, it will never be because it endorses a particular manufacturer. It was designed by a group of people to make a profit, from direct sales or royalties. It has become a ‘de facto’ industry standard, patents have long expired. Anyone can produce it.
Now here is the fun part, companies have engineers, engineers do NOT make decisions, marketing departments make decisions, marketing guys are not engineers. Their job is to market, to make money, the more the better.
Bridgeport gained popularity during WWII, Bridgeport sold the best (least affordable) knee mill in the country. We needed a lot of them. They came with collets that were made by the same company. More money, more collets, single vendor.. Bridgeport.
The war ended, people (machinists) in general buy what they know, Bridgeport. Good or bad doesn’t matter. Buy what you know.
Tada, a de facto standard is born. It only took, one marketing department, one war, and what ? 55 million dead?
You have to remember during WWII the United States produced more machinery and more heavy equipment then was EVER produced up until that time. We out produced the entire world and all of history up until then. That is a HUGE achievement.
So the R8 has earned its respect, but it is not the better tool, it is the better marketed tool.
Their lies the difference.
Aaron Moss
www.IndustrialHobbies.com