Re: Milling lesson
- --- In GrizHFMinimill@yahoogroups.com, Larry Rudd <lrudd70@...> wrote:
>I agree 100% with the last piece of advice in principle. However, even *after* the fact it is difficult to get the shopvac to get the chips. They seem to cling to everything mixed with the lubrication :-) I have taken to cleaning them out with a brush after each pass and blowing them out with compressed air (which of course gets them into other places you do not want them to be!)
> You have received some good advice here, but I don't think anyone mentioned trying a roughing end mill.
> Try one, I think you will be amazed. Also I would keep the shop vac on, pulling all those chips out fast.
- --- In GrizHFMinimill@yahoogroups.com, Bill Williams <BWMSBLDR@...> wrote:
>That seems to be the consensus. The last picture I think shows the four flutes. Well, three flutes, really, by then...
> You didn't say if you were using a two flute or a four flute mill. The
> four flute mills tend to climb much worse than the two.
- --- In GrizHFMinimill@yahoogroups.com, gerry waclawiak <gerrywac@...> wrote:
>***For the four-flutes it may be even less. I have not shown all I have done, but when I tried 0.100" passess there was a definite trend for the slot to skew.
> The min-mills are not the most rigid in the world and need to be treated reasonable gently if the relative lack of rigidity compared to industrial machines is not to become apparent.
> A rough rule of thumb for cutting depth is half the diameter of the cutter, so for 1/4" 1/8"per pass so three passes to entend your slots.
> Cutting speed and feed are also important and for steel you should be using a cutting lubricantif you are to get reasonable life from your cutters.***I think I mentioned the Rapid Tap. As far as I can see the speed and feed calculation is purely a guideline even if you *could* determine the rpm of your mill with any accuracy. For instance using 90 SFM as the top speed for soft steel the rpm recommended is about 1500 for 1/4" cutter. No way can I get that high with the mini! The thing would shake itself apart.
I have found no definite reference explaining why *slower* speeds than those calculated are in any way detrimental to the process or the machinery and I have always erred on the slow side. If anything the original determination of speeds and feeds was based on the tool lasting 1.5 hours before needing resharpening.
I defy enyone to determine the feed rate with accuracy using the mini. In any case, paraphrasing the Machinery's Book recommendation, feed for rough milling should be "all that the machine, work, tool and fixture will withstand" or in my terms "don't push it".
>***Now I have a further excuse going through catalogs :-)
> I haven't really tried chinese cutters extensively and haven't been over impressed with what I have.Here in the uk there are a lot of companies catering for the model engineering hobby market and you can usually get well priced branded cutters or good regrinds relatively cheaply
- --- In GrizHFMinimill@yahoogroups.com, "Michael" <mkoblic@...> wrote:
> I agree 100% with the last piece of advice in principle. However, even *after* the fact it is difficult to get the shopvac to get the chips. They seem to cling to everything mixed with the lubrication :-) I have taken to cleaning them out with a brush after each pass and blowing them out with compressed air (which of course gets them into other places you do not want them to be!)
This is my first post here,I agreed that the best way is to use a brush and not compress air as you will be blowing tiny chips all over your shop which take days to sweep/vac clean. you know the wife factor....
For roughing pass I use emulsion oil with a lots of water to dilute it, while finishing pass I use straight gear cutting oil which the chips stick to endmill like magnet!
Any one tried squaring piece of 6"X4"X3/4" 1045 carbon steel with the X2 mill? This material eat carbide endmill and HSS won't even touch it!
I'm bracing my X2 Z-axis column now, I suspect the short carbide end mill life could be due to hammering from the dovetail column flexing. Any input on this?
- The handfull of slots I've cut started and ended with a drilled hole, then plunged in some with an end-mill(never more than .40 or .50), milled to the next hole, plunge in some more, back up, until it was cut all the way through. That was slow going and chips piled up in the way--even with the holes at the ends.
Next few I did by chain-drilling a bunch of holes, then cleaning up with an end-mill. This was easier on the machine and less chips in the way but still slow (and won't really work if you aren't going completely thru the workpiece).
I saw a vid the other day where they milled a slot by plunging down to depth, retracting, moving over a few thou, plunging down again, repeat as needed. Used the "end" of the end-mill for the brute force work. I guess they finished up with a final end-to-end pass. Never seen that method before.
So is there a right way or wrong way to cut a slot?
--- In GrizHFMinimill@yahoogroups.com, "Mike W" <winklmj@...> wrote:
> So is there a right way or wrong way to cut a slot?
Yes. Any way that doesn't give you the slot you want is the wrong way.
Paul in Pittsfield