Its Just not as Exciting When Its Boring

Whenever I go to a home improvement store I always browse through the tool sets that are on display. I look at them because I like tools that make my work easier but I also want to see how they are packaged and marketed. I think one of the best at this is Dremel. They package sets of bits for sharpening lawn mower blades, cleaning and polishing golf clubs, removing grout and many other general and special purpose applications.

DBL-202B Boring Set

Creating a boring set package is just not as exciting. There are few variables; the diameter of the bore, the depth of the bore, the style of spindle and the material to be bored. For many years, Criterion has offered some basic boring head sets mostly for manual milling machines. It made sense to offer a DBL-202 bring head, R-8 shank all of the brazed boring tools that  would fit in the head (either in C-6 or C-2 carbide) packaged in a nice case where it could all be stored because manual milling machines did a wide variety of work.

As CNC machining centers entered the manufacturing arena they were not used in the same manner as the manual milling machines they were used for production because they made many parts exactly the same because the computer controlled the machine movements. Because they were a production machine so it did not make sense to offer a kit when the CNC milling machines did not require the same versatility as the manual milling machines.

CB-202B Boring Head, CT40 Tool Holder and Boring Bar

CB-202B Boring Set

The continued development and progression of using CNC machining centers has made them into excellent prototype machines. The capability of accurately producing a prototype part to the print is incomparable to a manual milling machine.  Because of this Criterion has added 3 new boring sets to our product line. Our CB-202B boring head, a set of indexable insert boring bars, a cross hole boring bar and either a CT40, BT40 or HSK63A shank in a convenient storage case give the versatility to produce bores from .250” to 6.687” in diameter.

Reduced Operation Cost

A customer called who wanted to bore a number of holes from 1.500" to 2.250" in diameter in aluminum. He wanted to know if he could run his boring head at 1,000 RPM. He has a number of Criterion 202 and 203 style boring heads and just wasn't sure what would be the best choice.

The size range of the bores made the 202 style the best choice for the application. He would have been able to reach the desired RPM on most of the bores and his parameters would have allowed him to produce them in about 30 seconds. I asked if he would be interested in producing the bores in 10 seconds or less which startled him because he had not thought about being able to do it that fast.

We then discussed the balance kit for the 202 style boring heads which gives it the capability of operating at speeds up to 5,00RPM. It uses a chart, a series of 6 balancing shafts and 4 balancing weights. The benefit for this customer was he could reducing the producing cost of this operation by 80%. Some additional benefits gained were improved surface finish and longer tool life from operating the carbide insert at the optimum SFPM. There will be less pressure on the spindle from the imbalance for the off-set on the boring head. These are not as easy to put a value on as the reduction in time but no less important as a savings.

If you have any questions on how to possibly improve your boring operations please contact us. We would very much enjoy working with you.

50 Years of Service - Is it Time to Retire?

For over 50 years Criterion Machine Works has produced the DBL series of boring heads. These boring heads were designed for manual milling machines that predominately used R-8 shanks. The mounting end was chamfered to match the spindle diameter of the R-8 shank. 

DBL-202B Boring Head
Designed for Manual Milling Machines

In its day this was one of the most popular boring heads available. It offered the user a large range from .250” to 6.687” in diameter. The .001” on diameter dial adjustment was equal or more precise than other models available at the time. It was not uncommon for machine shops to be started with the purchase of a Bridgeport Mill, a set of R-8 collets, a Kurt vise and a Criterion DBL boring head.

CB-202B Boring Head
Designed for CNC Machining Centers

As CNC machining centers grew in popularity, we introduced our CB Style Boring Head. The CB series boring heads were designed with a larger mounting face to be compatible with the tool holders used on CNC machines. The larger mounting surface also gives a more rigid and stable connection for performing a boring operation. All the ranges and adjustability features of the various DBL models were maintained in the CB design.






The CB style boring heads will perform equally as well as the DBL style in a manual milling machining operations. Unfortunately, the same is not true of the DBL style the smaller mounting surface is a disadvantage in CNC machining center operations.

Criterion 202B Balance Kit operates at speeds up to 5,000 RPM

Criterion Machine Works has introduced a balancing kit for their 202B boring heads. 202B boring heads now can be operated at speeds up to 5,000 RPM. 

The balance kit is a series of 4 weights, 6 shafts and a balance chart. When the weights and shafts are assembled in the correct combinations the boring head can rotate at 5,000 RPM with out introducing vibrations to the operation. 


Criterion also provides complete Modular Boring Systems so you can select standard components instead of investing in special boring tools. The Cri-Bore and Cri-Twin Modular Boring Systems will stand up to not only your toughest metal removal requirements but also your tightest tolerance requirements. 


Criterion’s Boring Heads, Boring Bars, Boring Tools, and Modular Boring Systems have been the Industry Standard for over 70 years. Criterion is proud to be your Partner in Precision Boring. For more information, please visit www.criterionmachineworks.com