[WWWOODMAN]

I have been machining thermofused melamine on 3/4" particle board cabinet parts for years on my point to point machine. I only recently started having problems with chipping on the edge of most every groove, after running only a few parts with a new bit. The bit is 1/2" down shear. A groove in my case is a 1/4" X 3/4" plow, @ 24" long.

I understand the problem is shared between tooling and material.

I need to be educated in carbide bits. Are there differing Grades, Strengths? I need an unbiased answer, rather than a salesperson....doing his/her job.

Please be specific. I have equivalent to a mile of grooves to cut, and I cant stop for a bit change every 50 feet or so,

Thanks for any input or point of reference that you can offer......

WWWOODMAN

[Gumby]

I have been machining thermofused melamine on 3/4" particle board cabinet parts for years on my point to point machine. I only recently started having problems with chipping on the edge of most every groove, after running only a few parts with a new bit. The bit is 1/2" down shear. A groove in my case is a 1/4" X 3/4" plow, @ 24" long.

I understand the problem is shared between tooling and material.

I need to be educated in carbide bits. Are there differing Grades, Strengths? I need an unbiased answer, rather than a salesperson....doing his/her job.

Please be specific. I have equivalent to a mile of grooves to cut, and I cant stop for a bit change every 50 feet or so,

Thanks for any input or point of reference that you can offer......

WWWOODMAN

You'll want to look for the highest rupture strength carbide you can get (ie usually a nanograin carbide) and your best bet is going to be a diamond based coating if you are looking for extreme tool life. DLC (Diamond Like Carbon) has one of the best wear rates of any cutting tool coating. They use this for cutting PCB boards and it usually increases tool life by a factor of 10 over uncoated carbide in abrasive materials. It doesn't come cheap but my guess is that one tool would cut more than you need.

I wish I could recommend a specific tool for you but I don't work with wood much. I know the down shears have a very different helix angle but will an endmill work for your purpose?

What RPM are you running at?

[ger21]

Melamine can be extremely abrasive on tooling. When I don't have a lot of parts, I use an Amana with an insert, but it won't last as long as a spiral. On our point to point, we use a grooving sawblade, this will last the longest before chipping, if you have one, and if it works for you.

Ramping down along the cut from 0 to the full depth, then come back at full depth, will use more of the cutting edge and give you longer tool life, but it'll take longer to cut. Using one to to rough the slot and another to take a light finish pass will give very long tool life with good cut quality, IF you have two routers or an ATC and again, can afford the extra time.

Assuming your cutting the dado in two passes, at full depth, rpm and feedrate are important for longest tool life. Talk to your tool manufacturer to get the right range for the tool your using, and do some testing to dial in a good combination. Try doing it as fast as possible.

What brand bits are you using. We use mostly Vortex, but I've had good results with an Amana on occasion.

If you are doing 2500+ parts, then diamond might be the answer. $200-$250 for a bit would be better than buying 10 carbide bits.

One last thing, would be to try a different brand of board.