Getting to Know Aggregate Tools

A newcomer to CNC asks for a basic explanation of what aggregates are and how they work and gets one. April 10, 2008

I am new to the CNC world and just got the okay from the lease company to order my new CNC machine. I was looking at the final quote and noticed with the tool bar I am getting, it states that aggregate tools will not work in this configuration. Just out of curiosity, what is an aggregate tool used for, and is this important or not for making cabinets?

Forum Responses
(CNC Forum)
From contributor B:
An aggregate head is a secondary attachment that connects to the spindle on your router. Most base level routers do not have aggregate heads included, although they can probably be added down the road. My guess is that your tool bar or part of the tool changing system on the spindle is somehow in the way of where an aggregate head would mount in the spindle. Aggregate heads are rather costly add-ons, and may require an interface component, such as a C-axis, on the spindle. You would need a specific task to be done with your router to require a specific aggregate head. General cabinet work cutting typically would not require one, but if you had one, you could probably find uses for it.

From contributor G:
Aggregate heads allow you to expand the capabilities of your CNC router. An aggregate attaches to the spindle of the router and, through a series of gears, allows you to perform tasks such as running a vertical saw blade, create even groove depths, route the side of a part, hold moulder heads/corrugated knives for profiling, and much more.

From contributor P:
Even though your tool magazine may be not be capable of holding an aggregate head, it is still possible that an aggregate can be manually inserted. Although I have a lot of respect for the postings made by contributor B, in this case I disagree with him on the comment that aggregate heads are a rather costly add-on. I believe that an investment in an aggregate head can be the best investment you can make if the correct aggregate tool is used in the correct manner. The addition of an aggregate tool will often allow you to do things with your new CNC machine that you normally just could not do. This could mean additional machining that would need to be done as a second operation, adding handling and possible damaging of the work piece. Furthermore, the addition of a C axis is not required in order for an aggregate tool to work on your machine. Benz aggregate heads are built with a modular design which means that the head can be rotated on the horizontal plane manually allowing the head to access all sides of your work piece.

Take some time to see what an aggregate can do for you. Then talk to your machine supplier and see what is involved in making the machine "aggregate ready."

From contributor M:
Since the questioner is, by his own admission, new to the CNC world, perhaps this explanation will suffice.

Typically router spindles are mounted perpendicular to the bed/table. Aggregate holders (or angled milling attachments as those of us that cross over to metal also call them) are special holders which allow you to mount, orient and use bits/cutters at angles other than perpendicular to the table. This enables you to present tooling to the edges of the work piece/panel that otherwise you could not machine.

Depending on what machine you purchased, aggregates may not even be an option. Some of the spindles on entry level and more economically priced routers will not support aggregates.

I have used both Benz and Techniks aggregates and have found both to be high quality products. In reference to the comments regarding cost - "cost" is a very relative term. There is a huge difference in asking a 7 digit a year company to invest in the same thing you would ask a 5 digit a year company to invest in. And, if you do not believe that there are a lot of 5 digit (in some cases less that 60k a year - gross sales!) companies out there that use CNC, I can take you to some. That said, if you can afford an aggregate and if you have valid applications for aggregates, it is definitely worth investing the time in looking into.

The statements regarding the "C" axis were accurate. You do not need to have a "C" axis to deploy aggregates, although it does expand their capabilities when you do have one. Aggregates have what is commonly known as an anti-rotation pin. This pin enables the body or casing of the aggregate to stay stable, while the spindle portion spins at the desired RPM. "C" axes allow for orienting the body or casing of the aggregate automatically using this pin. In effect presenting the cutting edges to multiple surfaces with minimal human intervention. It will also allow tangential tracking which enables the aggregate cutter to follow or create a predetermined contour. The addition of this type of 4th axis to a CNC router is typically a costly option. It is not mandatory to use aggregates. I know HSD offers static plates which mount on the spindle that offer 4 position (on 90 degrees) manual orientation mounting of aggregates to their spindles. In fact, I have removed and machined additional 45 degree mounting slots on these plates for added flexibility. Some machines with tool changers do not permit aggregates to be used in their tool changers; others may only permit aggregates to be used in select tool changers (when more than one tool change location is present).

From the original questioner:
Thanks for all the responses. I just simply did not know what the aggregate tool was used for, and while I read a quote on the machine this past weekend stating that I could not use an aggregate tool with the particular tool bar setup that I had chosen. I called the company yesterday to find out the importance of this tool in my particular business and was told that it would not play a part in my business, but the stock tool bar could be modified at a later date if I should decide to need an aggregate tool. I will not be doing any horizontal machining. Thanks for coming through again and providing me with valuable info.

From contributor H:
One more thought to offer you. You say that the "tool bar" is not capable of holding an aggregate. Find out before you order if the router spindle can accept one. If it can't, you may want to consider ordering it with the capability right away or you will end up having to swap it out later. It will be less cost now than later. Another advantage of doing this now is that even though the tool bar can't hold an aggregate, you may still have an option for a manual tool change allowing you to insert an aggregate by hand. This is common with many aggregates because some are simply too large to fit into most if not all tool bars or carousels. We currently have two like that here.