xoneeleven wrote:
As far as checking the bed flatness, I have a spoilboard that I flattened using an end mill. I would expect the bed to be very flat, still. It is in pristine shape. However, I will certainly check it with a straight edge tomorrow.
I really do appreciate the advice, gentlemen.
Glad to help, hope progress is made.
That makes sense with the F&S being fast; you do have to be a little cautious with the sharks because of the HDPE elements. However, as you become more familiar, you'll come to realize that feeds and speeds are not nearly as much about machine rigidity as they are about the bit in the material. So, if your friend is cutting using those parameters in the same material, then they are also doing it wrong. That is especially true of that 0.125" DOC 10% SO cut: it's moving way too fast at that spindle speed to cut the wood properly. It's all about the chipload, and that has a wicked high chip load, and that's what leading to the shredding. Wood has a wider sweet-spot for the cut parameters, but that does not mean the params can just be chosen willy-nilly. Good cuts are ones that remove the material quickly, with the necessary finish quality, within the limits of the machine. Spinning or moving a bit too fast OR too slowly will cause the bit to dull more quickly than when used properly, and it will produce lower-quality cuts, with burrs and all that.
E.g,. I have a 3/16 and 1/4" endmill I've been using for over a month in many different projects over the last two months, and they're still going strong. Why? Because I've tuned those F&S so they are optimal for the bit and material, while working within the machine's capabilities for making the cuts accurate, and not letting it "get into trouble" because of the lack of rigidity. The thing is, when it's all said and done, your 1/4" end mill and your wood are the same as his 1/4" end mill, so getting high-quality accurate cuts is still going to want the same parameters.
The other day, I got a sample part from my local endmill supplier (they manufacture their own line of endmills) where they did some amazing cuts on a $250K machine...and it had chatter, and bad pocket-bottom flatness, and all the things I used to see on my machine, and in some ways, I get better results than they did. Yes, they ran it faster and deeper, but the cutting geometry was the same, and the effects of deflection and chatter were present on their part too.
For the spoilboard and ruler, I was actually talking about the stock material warping, and lifting itself up from the spoilboard, but in the middle. So, the straightedge should be applied to the backside of the wood you're carving, not to the spoilboard's leveled surface.
Can you describe what effect you're going for, using the tapered ball mill after the v-bit in the YHVH toolpath? Usually that V-bit cut would be the end of it, since it is the finishing pass to the 0.250" endmill's clearance (aka roughing, or hogging) pass.
Well, tomorrow will shed more light on the subject. Good luck
.
Regards,
Thom