Best Tool Head for Cutting Grooves?

A saw blade or a router bit could give the best results, depending on the situation. December 10, 2007

Question
We are looking to buy a CNC machining center and have a few questions. Is it better to groove with a saw or router bit?

Forum Responses
(CNC Forum)
From contributor A:
Groove is an understanding of rhythmic patterning. As a result it depends on the situation. A saw will typically last longer and can cut deeper when the groove is very deep, but it will leave a ramp if you start inside the panel. Also, a saw usually will not make a chip-free cut unless everything is set up perfectly. A proper router bit will be a better choice for clean cuts and curvilinear grooves. In my experience, get a machine with both and use each accordingly.



From contributor J:
We have an XY saw on our CNC. We almost never use it, even for grooving. As contributor A said, it never provides as clean a cut as a router bit. If you have a tool changer, you more easily change the bit size than the blade size, if that's an issue. Also, with a router, you can route curved and angled grooves, if that's an issue.


From contributor M:
I use three methods. I feel that I get a better cut for folds with the saw. If I'm folding odd angles, I use a molder head with carbide knives. If I'm nesting with little room for lead in and lead out, then I use insert router bits. The problem with router bits and long runs is the geometry of the tool. There is very little movement at the tip of the tool which causes heat and a tendency to make a slight bulge on the back side of the material. I wouldn't trade my saw for anything, but we make a lot of cuts with standard and thin kerf 10" blades. Bottom line is all the methods work. More choices are always better than less.


From the original questioner:
We would be grooving gables and tops and bottoms of cabinets. The size of the groove would be 5/16" deep by 3/16" wide. I was worried that the router bit would not hold up to this kind of work.


From contributor P:
We almost always use the grooving saw for that size at 20 meters per minute, always climb cutting. Only time we don't get a good finish is when the cutter is really dull. I don't think a 3/16 router bit would like going almost 800" min.


From contributor L:
I agree with the use of a saw for speed and versatility overall. You, of course, would need a C axis on the machine. Make sure you specify an aggregate with a 100% duty cycle for extended cut times.


From contributor M:
For doing a lot or heavy grooving, I'd skip the C axis and an aggregate with regard to sawing. The advantage of an aggregate is variable rpm, but the big disadvantage is lack of rigidity. With a new machine, it's easy enough to spec a dedicated 360 indexable unit. I just have a 0-90 unit, but I think most manufacturers just put on the 360 unit now. The other plus to a dedicated saw is there is enough room for a standard 10" diameter blade for doing rip cuts or kerfing panels.


From contributor T:
I tend to think that it really depends on the application. For example, in a nested-based situation, the router bit works much better for many of the reasons noted above. However, in a P2P application (machining single parts), the saw works much faster and with a higher quality finish. Another issue is cross grain grooving, as the saw will generally outperform the router bit.