Richon Tools order

[Chuck in E. TN]

I received my large order of end mills from Richon Tools today. I purchased 32 cutters, in pairs, from 1/16” to 5/8”, 2 and 4 flute,  and some metric ball end mills. They came in individual plastic tubes, wrapped in a plastic bag, inside a very tough plastic outer bag.
I opened a few for a look. I was surprised to find several had what appear to be chips in the end cutting edge. At first I thought they were just the profile where the flutes met the cutting edge, but not all of them have this chip. Is this normal? I really don’t want to use them if they are damaged/defective.
Also, to preclude abuse of my new tools, does anyone have or know of a spreadsheet for determining feeds and speeds based on mill cutter diameter? Is there a simple formula that I can put into Excel that would give me a starting RPM, based on cutter diameter and material such as steel, aluminum, or brass?

Chuck in E. TN

[dickda1]

Hi Chuck,

Take a look at the following:

http://www.custompartnet.com/calculator/milling-speed-and-feed or
http://its.fvtc.edu/machshop3/speedCalc/feedratecalc.htm

Most of the wear occurs at the tip of the end mill - the only part that is easy to sharpen.  Chips on the end cutting edge don't sound normal.

-Dick

[DaveH]

I'm not so sure Industrial/commercial speeds and feeds are really that useful. Mainly because the critria used is not always known.

Home shop milling on home shop milling machines is a little different to using a Bridgeport, either at home or in Industry.

Just my thoughts.

Chuck,     At the top the page in the "How To's" page  there is a "Sticky" about speeds and feeds.
 
DaveH

[AdeV]

Machinery's Handbook (if you don't have one.... get one.... it doesn't have to be the latest edition, I have no. 24 and it cost me about a tenner through Amazon IIRC) has a bunch of speed/feed charts for various metals. I took those charts, halved the numbers and printed a sheet out which lives next to the mill.

To be honest, I hardly ever use it though, I just go with what "sounds" right. If the machine is clunking and banging, turn the RPMs up. If it's still moaning, reduce the feed rate. Or grit you teeth and ignore it as best you can... Use plenty of cutting oil if you're running at what feels like high speed. Making smoke is fine - making fire is going a bit fast.

Don't forget, depth of cut has an effect too - the less the cut, the faster you can feed (or keep the feed slow for a glass-smooth finish).

[andyf]

Chuck, are the "chips" symmetrical, in the sense that there's one out of each cutting edge of the tools which exhibit them? If so, they are probably supposed to be there.

This pic of an unused Chinese endmill is very blurred, but you can see that the edge at 12 o'clock seems to have had a bite taken out of it. The other three are just the same, as is just about visible at 9 o'clock.



Andy

[kvom]

I have heard people say that they got good cutters from Richon.   However, I ordered a good assortment of carbide endmills from them a while back, and they are crap.  Even with conservative feeds and speeds I never got a single endmill to make a single part without snapping.   

[Chuck in E. TN]

KVOM, I'll have to see, the ones I ordered are all HSS.
After digesting the input here and on a couple of other forums, I have concluded that the Richon end mills are not chipped. There were, however, a few other problems with the order. I had ordered a pair of 10 mm ball Nose end mills and received a pair of straight 10 mm end mills, one extra ˝” 2 Flute, and 2 extra 3/8” 4 Flutes and a substituted part # for the 3/16 4 flutes.
I emailed Peter at Richon to apologize for the misunderstanding of the “Chipped” cutting edges and point out the other errors.
Next step is to actually cut something! I will comment here as to cutting quality later, that is if this “Noob” can determine quality!
I also will work on building an Excel based feed and speed Ballpark Calculator that I can enter material and cutter diameter to get a conservative RPM setting.
Thanks to all that commented on this thread.
Chuck in E. TN

[kvom]

I use G-wizard for F&S calculations, but that's more because I have a CNC mill and use carbide endmills with it.  It also handles drilling F&S.

For a manual mill, you generally need the spindle speed, and unless you have a DRO that indicates feed, the feed will be mostly by feel and chip color.  For most materials and em size, you quickly learn a comfortable number for RPM and DOC.

[lordedmond]

Chuck

for rpm with HSS I use a simple formula   cutting speed X 320 divided by cutter dia in mm


eg for MS its 18 to 25 
and a 10 mm HSS cutter

therefore  ball park figure  gives (20 x 320)/ 10 = 640 rpm

If you what I will dig out the remaining surface speed recommendation when I get down to the WS got to get the personal wheels warmed up

[kvom]

G-wizard would yield a higher RPM than what Lordedmond's formula shows, bit I set it for a 1" stickout.

The thing that breaks endmills is deflection.  A HSS endmill should not be allowed to deflect more than .001" at the tip, and the amount of deflection for a given F&S will depend on how far it sticks out from the collet.  The deflection increases by the cube of the stickout, so the longer the flutes the slowed the feed.  The slower the feed, the higher the RPM to give a proper chipload.  The number of flutes then comes into play for chipload, as does width of cut.

The depth of cut doesn't really come into the equation since the deflection will not increase with DOC.  What does happen with increased DOC is an increase in required horsepower plus an increase in heat.  So now F&S will depend a lot on how rigid your mill is, how large the spindle motor is, and whether there's coolant.

In the end, experimentation is the best teacher, and cheap endmills are a good way to experiment.  Listen to the cutter and watch the chip color.

[Bernd]

I may be wrong, but it seems to me that the issue of the chip in the cutter hasn't been addressed fully. I have taken some pictures of some larger end mills showing the so called chip.







What you see is the radius ground on the spiral part of the cutter for clearence. Here are two pics. Not very sharp, but I think you'll get the idea.





Best I could do with a point and shoot digital. Hope it's helped to clear up the "chipped cutter" problem.

Bernd

[rleete]

My 4 flutes are all like that.

[Fergus OMore]

Quite simply, the 'chips' are where the flutes finish.
Actually, they can't do anything else.

What seems to have escaped comment is whether the extreme edges are sharp and therefore ready to chip or rounded which reinforces the tool but gives a rounded edge on the work- which makes the work stronger.

Blame Archimedes- not me!

[Bernd]

I have a feeling I'm still not getting through with my explination. What you are seeing is not, I repeat is not a chipped cutter. It is the result of grinding the cutting edge of the spiral flute. Take a closer look and you'll see what I mean.

Bernd

[winklmj]

I have a feeling I'm still not getting through with my explination. What you are seeing is not, I repeat is not a chipped cutter. It is the result of grinding the cutting edge of the spiral flute. Take a closer look and you'll see what I mean.

Bernd

Yeah, ummm, if anyone has any cutters that are "chipped" like those pics--feel free to send them to me.

[PeterE]

Quite simply, the 'chips' are where the flutes finish.
Actually, they can't do anything else.

What seems to have escaped comment is whether the extreme edges are sharp and therefore ready to chip or rounded which reinforces the tool but gives a rounded edge on the work- which makes the work stronger.

Blame Archimedes- not me!

I did take an extra look at the latest of my cutters and they have exactly the same "profile" on the cutting edge. I noticed it in the beginning before use, but as the cutter felt sharp to the touch I did not  think any more about it. It does work well.

Taking a further look I find that on my cutters the extreme outside edge/corner is really sharp and could actually do with a very light rounding off. That would mean that I will gain two things - firstly that the tool gets stronger due to less risk of chipping the cutting edge corners, and secondly that I will get less sharp "roses" from the cutter on the surface = a better surface.

Coming to think of it, I took a third look - my eyes are getting strained now  - at an older cutter which does not have the small curve in the cutting edge. There I found that the flutes are ground in a different manner, and that ought to be the reason for the difference in cutting edge appearance.  Correct me if I´m wrong please.

Br

/Peter

(Edit: Spelling errors)

[Fergus OMore]

Peter,

I'm not an engineer but I do sharpen the odd cutter. If you are careful, you will notice that the cutter edges form is a concave one on ordinary cutters. Hence the outer edges are sticking out! And there fore it is wise to remove the very sharp tips for the reasons stated.

Having said all that I have no factual evidence about why modern cutters have a spiral within a spiral. I would assume that it is for more efficient milling.

If one thinks about removal of metal, the lathe tool is only a single lipped milling cutter- or vice versa.

Regards

[DaveH]

Peter,
If one thinks about removal of metal, the lathe tool is only a single lipped milling cutter- or vice versa.
Regards

Not really, most lathe tools are 'single point' tools, fly cutting gets close on a milling machine.
 
DaveH

[Fergus OMore]

We are merely going off at right angles! A Milling machine is really only a lathe at right angles to the normal.
Maudsley invented the slide on the lathe which became the table on the mill.

One sticks a spindle at the right hand end of a lathe- but it is only because most of us are right handed.

If push comes to shove, I was quoting Archimedes but we were doing all sorts of quite precise measurement some 4000 and more years ago.

Actually, we( or our predecessors) were using the planet Venus. Read up Professor Thom.

Think about it. There was a very recent question about what is called trepanning. I answered some of it but the old Egyptians were trepanning living skulls at the time of the Pyramids. Probably they would have given a more detailed answer!
I was prattling somewhere about cutting spirals and the ancients were cutting them just down the road from me- in the 1100's- by hand.

Apologies but that is the history book- but most is remains to be rediscovered.

[bp]

Fergus OMore said "A Milling machine is really only a lathe at right angles to the normal."

I've always looked at it as, "A lathe turns the workpiece, whilst a mill turns the cutter"  Obviously there will be exceptions but its not a bad basic rule of thumb.  The axis of rotation of (either the workpiece or the tool!!) can be either horizontal, vertical or something else, as long as the machine is designed correctly, it's irrelevant.
After all machines in the Northern hemisphere are upside down compared to the Normal or Southern hemisphere.
cheers
Bill Pudney