Balanced Tools G6.3 vs G2.5

**Djstorm100** · 02-22-2021, 08:34 AM

What is the true difference in these besides RPM?

If a machine has max spindle rpm of 15,000. I'll tend to buy tooling that's rated to 25k rpm. I guess my logic (although flawed) is more of a "safety margin" by going with the G2.5 balance vs G6.3. I mostly use ER collets, side lock and a few heat shrink. Which all are G2.5 rated to 25,000rpm. I understand with all these, they are balance with out the nut, no tool, etc.

Having said all that, does it really matter which you go with as long you don't get near or over the spec rpm? (20k and 25K in this example)

**metalmadness** · 02-22-2021, 11:42 AM

Ehh there can be many variables in how this works.

How big are your tools diameters? Bigger tools at higher RPMs need to be better balanaced to maintain integrity of the system. If you have a big tool in a moderately well balanced toolholder spinning at 10K and a big tool in a really well balanced toolholder spinning at 10K, the better balancing is going to improve the whole system - bearings will wear slower, drawbar will last longer, better harmonics, etc etc. Now you may think "thats such a small amount of difference how could it ever matter?" And youd be right if we are talking just that one tool, but you never run just one tool. You run 50 tools for 10-20 hours per day, so all of that is going to add up. In theory anyways. I could be totally wrong.

IMO buy the best tools you can afford. If you can afford a $100 Shars, buy that. If you can afford an $800 Haimer hydraulic, buy that. I have a $130 Shars shrink fit curved nose holder that I LOVE because it has the curvature for a fraction of the price of an MST holder. Its decently balanced, but I wouldn't run the thing on a Grob or Hermle machine.

At the end of the day I don't think it truly matters that much, but someone with better knowledge of this topic may offer some insight.

And if youre really worried about this, you can buy a balancing machine and balance your own tooling systems.

**Djstorm100** · 02-23-2021, 10:01 AM

Originally Posted by metalmadness

Ehh there can be many variables in how this works.

How big are your tools diameters? Bigger tools at higher RPMs need to be better balanaced to maintain integrity of the system. If you have a big tool in a moderately well balanced toolholder spinning at 10K and a big tool in a really well balanced toolholder spinning at 10K, the better balancing is going to improve the whole system - bearings will wear slower, drawbar will last longer, better harmonics, etc etc. Now you may think "thats such a small amount of difference how could it ever matter?" And youd be right if we are talking just that one tool, but you never run just one tool. You run 50 tools for 10-20 hours per day, so all of that is going to add up. In theory anyways. I could be totally wrong.

IMO buy the best tools you can afford. If you can afford a $100 Shars, buy that. If you can afford an $800 Haimer hydraulic, buy that. I have a $130 Shars shrink fit curved nose holder that I LOVE because it has the curvature for a fraction of the price of an MST holder. Its decently balanced, but I wouldn't run the thing on a Grob or Hermle machine.

At the end of the day I don't think it truly matters that much, but someone with better knowledge of this topic may offer some insight.

And if youre really worried about this, you can buy a balancing machine and balance your own tooling systems.

Thanks for the wealth of info. Do you run the Shars at 12k or more?

**mhajicek** · 02-23-2021, 11:56 AM

Originally Posted by metalmadness

I have a $130 Shars shrink fit curved nose holder that I LOVE because it has the curvature for a fraction of the price of an MST holder.

Thanks for mentioning those. Hope they're back in stock soon.

**Matt_Maguire** · 02-25-2021, 05:19 PM

Originally Posted by Djstorm100

What is the true difference in these besides RPM?

If a machine has max spindle rpm of 15,000. I'll tend to buy tooling that's rated to 25k rpm. I guess my logic (although flawed) is more of a "safety margin" by going with the G2.5 balance vs G6.3. I mostly use ER collets, side lock and a few heat shrink. Which all are G2.5 rated to 25,000rpm. I understand with all these, they are balance with out the nut, no tool, etc.

Having said all that, does it really matter which you go with as long you don't get near or over the spec rpm? (20k and 25K in this example)

G-6.3 is the general rule for running machine tools except grinders. G-2.5 is better, going better than that the expense goes up fast. Attaching some stuff for general reference.

Good luck,
Matt