Quad Chamfering with Amana RCK-432 Bit

[BruceH]

I recently picked up the RC-1075 shank and one of these quad chamfering bits to add a touch of polish to some of the acrylic we've been cutting. Unfortunately, the documentation is a bit sparse, even erroneous in places. If anyone has used this rig, (or anything like it - see image below) I would appreciate any tips or info that you've gleaned from your experience.

Of particular interest:

How do I determine the offset for the path? (I see no indication of the inner radius of the cut.)
Can this bit handle plunge and cut into .177" acrylic (like the documentation suggests) or should it just follow a finishing pass?


Thanks!

26069

[waynelocke]

I don't have an answer but here is a short piece on cutting acrylic which I spotted earlier today, http://www.woodworkingnetwork.com/best-practices-guide/cutting-grinding-cutting-tools-grinders/how-rout-clear-edge-acrylic.

[bleeth]

Not only is there no radius given, but this bit actually looks off center. You would need to define the center line and measure to the profile side to get the offset.
I would be on the phone to Amana support-they should be able to help you out.
I'm kind of curious-how long is the CEL (cutting edge length) on the insert? since you are cutting 3/16 plastic (Which comes in slightly under at .177) do you have to go far into the table to get the shaped edge?
I can tell you that the insert itself must be seated exactly right in the mandrel or you will have problems. I have one of their insert v bits and it's a noisy son of a gun and doesn't do the job as smooth on acrylic as traditional carbide tipped tools.
If plunging I would ramp and lead in. I plunge into acrylic at .25 ips and keep the speed down (Don't recall my speed on thin material-haven't cut any lately but for larger part and a smaller bit I would likely hit 1.5ips to start and edge up from there to tune it if I was doing a lot. That's with an Alpha and 5HP spindle-Doesn't work the tool to hard but results in a cleaner edge than moving faster.

[Brady Watson]

If that bit is anything like the 'In Groove' line, I would err on the side of slow/caution when using it. I for one would certainly not do any plunge cutting whatsoever with it.

If your intention is to do some edge forming with it, consider programming the tool to come in from the edge using a lead in so that it ramps into the cut. Use your CAM program to get the majority of the action and if need be, hand code the lead in.

Lay the bit on a flatbed document scanner, and bring the JPG into VCP/Aspire. Trace it, scale it & make a Form Tool in the tool database. Then you can preview your toolpath using the toolpath simulation in the program.

-B

[BruceH]

It's definitely off center. The non-cutting edge is closer to center for obvious reasons. According to what I've read, the cutting depth officially need only be .008", but this is incorrect. The base of the bit has a toe about .0225" high before it slopes inward. Discrepancies like this are why I haven't bothered to contact Amana for details. They don't know what they have in this particular case. What I ended up doing to define the tool was to scan the bit in at an ultra high resolution (12800ppi), then traced it in Adobe Illustrator. Once I had the profile traced, I was able to find the true center. The innermost cutting radius is .067", which seems arbitrary. I'm going to do some trial cuts edging it closer and closer to the material until I can zero in the path offsets. I'll report back once I've done that.

[Chuck Keysor]

Bruce, I have the Amana "In-Groove" 8 piece set with the 1/2" shank. I bought it because I wanted an assortment of various tips for V-Carving, and because I liked my other conventional Amana bits.

I had a test board of MDF, and I had a series of decreasing sized text, which I cut with my CMT 60 and 90 degree bits, plus some other off-brands, and my then new In-Groove bits. I wanted to push the limits of how small of a font I could cleanly cut. The Amana "In-Groove" bits cut fabulously,,,,,, for a couple of lines. But after the first bit failed, I tried the next one, then the next one. Much to my dismay, 3 of the 4 v-bits in the set, failed in rapid succession, with the tips breaking off. The 4th bit, I simply didn't bother to even test.

There are 3 profile bits in the set, and they are off-set like what you pictured. I never bothered to even try and figure them out, as I figured they would just bust on me.

I called Tools Today, from whom I had purchased this set, so I could express my dissatisfaction. They told me to call Amana, and I am afraid I just set them aside and haven't touched them since.

Minutes of cutting tiny letters in MDF, and then catastrophic failure? I have never had any other bit fail me, other than to simply get dull after hours of use. These bits are not cheap, and I am still sorry I ever purchased them. (But I still like Amana, as all of their conventional bits have been excellent.)

Chuck

[Bob Eustace]

Exactly the same experience Chuck in bamboo! I did have a bit more success with alucabond though doing a small batch of dog tags. Spare bits are ridiculously expensive. Wont to buying again as Tools Today didnt want to know.

[BruceH]

Thanks for the feedback, folks. After some testing, I'm getting results that are unsurprisingly disappointing. Once I was able to accurately predict the bit's path, I tried a variety of feeds and speeds, and the best finish I was able to cut was quite rough and chipped. Much like the rest of you, I've been very please with my other Amana bits, so I'm considering this subcategory an anomaly. Although this is a very specialized tool. The fact that it can't do its one job on the primary material it was designed for is leaving me a bit dismayed. Oh well, you cut and learn.

[MogulTx]

I am really disappointed. After seeing the bit, I had come up with a neat idea that I thought would help my regular business and this bit (and your thread) is what spurred the idea. I will still try it- but will do it with one of my other bits- to see how smooth I can make an edge. I want to get close to a polished edge with a bit and then maybe finish it with firepolish.... we will see if my idea has any merit.

[bobmoore]

I wouldn't run that bit into spoilboard even .005". I don't have experience with that bit but I would only use it for edge cutting on elevated vacuum pods.