Amana bits not holding up

[Michael Simpson Virgina]

Well, while the Amana IN-Groove bits cut nice and clean, they just dont hold up. Every single V bit in the set, the end of the tip has broke off. This wont effect larger cuts but real fine work and PCB etching its a no-go. Just too fragile.

I have moved back to my standard Vgrove bits. This was an expensive experiment.

[Dan Hintz]

Have you considered switching to endmills for the PCBs? If anyone asks you to make an RF board (assuming you plan to offer the service), you'll need to use one anyway to get the edges nice and vertical to keep the board impedance as designed. On that note, have you tried other V-bits that survive, or is it just the Amana's that die a quick death? Are you slowly entering the board or do you drop into it (fiberglass can tear up bits pretty quick)?

One of the reason the PCB mills are generally desktop-sized units (other than the fact that few people need 4'x8' PCBs ) is that slop can be tightly controlled. When your copper layer is only a couple of mils thick (and the entire PCB itself is a few tens of mils), you can't afford to drop that bit in at any ol' height... and that base had better be very flat.

[Michael Simpson Virgina]

I have used end mills. The problem with them is that you have to go very slow or they will break. When I say slow I mean very slow. For instance with V bits I am doing 10ipm. I use end mill bits for board milling and drilling.

I have a couple V bits I purchased just for routing and they work pretty good. Not as clean or fine as the amana in-grove vbits. These do hold up as they have more mass near the tip. The amana bits are actualy blades and are thin. This is probably why they can make suce a precise cut.

Im not doing this to offer it as a service. I just need boards for some of my projects. Single layer boards are pretty easy. Dual layer boards are a little tricky. The top and botom layers have to line up with in a couple thousands or the board turns to crap. I created a fixture that works well.

The real problem I have is if the board is slightly warped. This one way I broke the amana bits. It hit a high spot in the board and snap. When I say high spot, I am talking thousands of an inch.

I have really put my machine design to the test and it has proved pretty accurate. I did have to move from the Dewalt 816 back to my Festool router because of runout. It wasnt much runout but was enough to muck things up. If I were going to do a lot of boards I would build a Single start ACME screw CNC. This would yeald me about 20,000 steps per inch. My 5-start Screws yeald me 4000 steps per inch.

Im working on a small R&P CNC and it will yeald only 1900 steps per inch. It will be interesting to see how well that system works on making PCB boards.

[Michael Simpson Virgina]

Here are how I have broken my Amana Vtip bits.

The first one broke when it fell out of the chuck as I was removing it. Another broke when I when the wrong direction when jogging. I went down when I ment to go up. Another tip broke when I bumped the bit while putting my dust sheild in place. The last one broke when it hit a high spot on a bad copper clad board. (Thank you RadioShack). These bits are extremly fragile. I think I gould break the tip off one just looking at it wrong.

The good news is that a new blade is only $20.

Now breaking end mills is another story. When you are dilling with and end mill thats only .025 or smaller, those things can break by just running them in a router with bad runout. They definatly are not meant for routers. The only success I have had using the small end mills is with my Festool router and my Foredom spindle.

[Scott Shepherd]

Doesn't sound like a failure of bits to me. You dropped it, you jogged the wrong way, you bumped it with the dust shield. How's that Amana's fault?

If you drop any v-bit on the tip, or plunge it, it's going to chip.

Now, if you were having problems while running, that would be a different story. The bit problem with all v-style bits is that you cannot turn enough RPM to get the surface footage to an acceptable level at that diameter. The edge of the bit is running good surface footage, but the closer to the center, you have a super low surface feet per minute calculation going on. V-bits will ALWAYS be problematic because of this.

[Paul Johnstone]

Well, while the Amana IN-Groove bits cut nice and clean, they just dont hold up. Every single V bit in the set, the end of the tip has broke off. This wont effect larger cuts but real fine work and PCB etching its a no-go. Just too fragile.

I have moved back to my standard Vgrove bits. This was an expensive experiment.

Thanks for the feedback.. I was considering trying this system but I think I will pass now.

[Michael Simpson Virgina]

When I say drop. I am talking about dropping the bit 2" onto MDF. While I do agree this was my falt. I have done this many time sith my other bits without the tip breaking off. While I am extra carefull now. The tips just dont hold up. We all make little mistakes from time to time and most of my V bits are more forgiving, the Amana bits are not. If you are not doing PCB or ultra fine engraving I would stick with the more standard V-Bits.

FYI the bit I am using now is a Kempston #202005 bit. I think I paid $12 on Amazon for it. It works very well. I just did two PCB boards with this bit and they turned out very nice.

All that said the Amana in-groove set also has some small profile blades for doing Round Overs, Ogees, and strait cuts. They are supposed to work well in plastic. I am going to give them a try. If they work well they could be nice for making small plaques and such.

[Bob Savage]

Michael,

Have you tried using o-Flute bits for the PCBs? I haven't cut PCB but I've done similar material that's used for electronic turret boards for guitar amplifiers and they work like a charm.

[John M Torrez]

Have you ever tried tools that are actually made for cutting PCBs? I cut 40 IPM at 24KRPM using our 60° with no problem. Stub endmills can go even faster then that depending on the diameter you are using. On top of that they don't cost as much as anything you are talking about (again depending on size).

[Michael Simpson Virgina]

Is it possible to get as 60 degree bit with a 1/4" bushing?

[Paul Grothouse]

I don't think this is a fair assement of this product. Failure to use proper programming with proper lead-ins and lead-out with a bit set like this is a bad idea. I have a 15hp CNC that could literally split firewood if you put a wedge on it, and I have never snapped on of these bits. These bits are extremly fine and accurate, I don't drop my chisels and not expect to see a chipped edge, these bits are no different.

The bits you using now are quite differently designed and for a different purpose. And for reference, most PCB prototype shops I worked with in a previous life, used diamond bits.

[Michael Simpson Virgina]

Let m me be clear. I did not say the bits were crap, cheap or junk. I have been very honest and forthcoming as to how I used and treated the bits. I merely pointed out the facts I have discovered. After I broke the first tip, I made it a point to treat the bits with care, and I still managed to break the tips.

The Kempston bit I am currently using works well enough. I will probably try the PreciseBits on my next board project. And while the Amana In-Groove set works on other projects, I will stay away from it for PCB etching.

[Mike Heidrick]

CMT makes their laser point 60 degree Vbit in 1/2 and 1/4" shank. I love that 3 flute bit!

[John M Torrez]

Is it possible to get as 60 degree bit with a 1/4" bushing?

Unfortunately we no longer have bushings for tools. It was quite cost prohibitive to get them made to our spec.

And for reference, most PCB prototype shops I worked with in a previous life, used diamond bits.

I am unfamiliar with diamond tools made for trace isolation (which is not to say they don't exist). If you have a link to these I would be quite interested in seeing them. Most diamond engraving tools are drags and as such not ideal for isolation. There are diamond cut router bits but these are not diamond and are made for routing out the board not isolation. I have seen some diamond tools that are close to these but again these are not meant for isolation.

[Dan Hintz]

And for reference, most PCB prototype shops I worked with in a previous life, used diamond bits.

Perhaps you're thinking of silicon carbide? About as long lasting as you'll get with those tough glass fibers in typical PCBs...