25mm Insert Milling Cutters

[jasonb]

Rather than Hyjack the two other threads where these cutters have recently been mentioned I thought I would start another.

Having just watched the video's of roger using his and his comments on noise I would be interested to know what cutting speed is being used as it sound s quite slow in the video and could be the reason for the noise. Also what inserts were being used?

I have said that I don't find mine excessively noisy and my machines are far less ridid than Rogers so that can't be the reason. Which leaves feeds, speeds and inserts.

Rogers video shows it cutting aluminium, I would be running at 5000rpm for this on the KX3 which is my max speed giving 400m/min though the inserts are good for at least twice that and using inserts for aluminium and non-ferrous, this video shows similar 1mm DOC as being used by Roger but 6 times the height on the roughing and finish contour, my phone distorts the motor noise but there is no major knocking when the tool starts cutting, feed is slower but that was for other reasons.



Even on steel I don't get so much knocking, this is the same tool but with general purpose inserts cutting steel, again 1mm DOC and 1750rpm. Machine is the even lighter SX2.7 hand fed. Watch from 12m 40sec

[uuu]

I use a 16mm tool quite a lot - it has two tips. I find on Aluminium and cast iron it's quite gentle, but makes more impact on steel. Contrary to normal endmill use, I find it's quietest when cutting at a shallow depth, but full width (or nearly full). I run at 1500rpm, my mill could go a bit faster, but it's comfortable at this speed.

Wilf

[oldnorton]

Regarding general noise and cutter RPM I have two thoughts that I will just put into the conversation.

Firstly, I am of the view that when you cut steels with an indexable tip you do need a proper depth of cut or the tip will risk polishing the steel face and wearing prematurely. If the tool is rotating at the 5,000 RPM or 1750 RPM then the bed feed needs perhaps to be much faster than shown in the video if the depth of cut rule is adhered to? I think this is why others, including me, will run a 50mm indexable head at perhaps 200-400 RPM.

Secondly, these types of facing jobs are invariably interrupted cuts, where each tip is walloping into the metal open edge as it comes round. This puts bounce in the tool head which then causes bounce in any gears in the drive system above. If I use shell cutters (I think that is what they are called) on my old-school SX3 or on my big Bridgeport, both of which have gears in the drive, you can hear the gear noise banging more than the cutting noise. I would guess a higher cutter speed would quieten it down with greater inertial energy rotating, but is the tip then cutting properly?

Is the KX3 all belt in it's drive?

I think both of the videos are shown cutting aluminium (?) with very fine shards, and I can't see those cuts being repeated on steel.

The subject interests me because I have been generally unhappy with my shell cutters, partly because of the interrupted cut noise, but mainly because of poor finish with the trailing tip, I think, picking up swarf and scuffing the surface it is failing to cut. Perhaps higher speeds would help but I guess high speed flood lubricant will be another help.

Norm

[jasonb]

Norm if you watch the second video from the start you will see me using the 63mm head on several materials on my X3 which has a similar 2 speed gear head to the SX3, feeds on that are also faster to give a better chip load than the first video. The KX3 and SX2.7 are bot direct belt drive and a lot quieter with any cutter.

Width of tool relative to width of work will reduce knocking if you ensure that at least one insert is always cutting, this applies more to facing cuts than side cutting.

The second video at 12.40 is the same cutter but taking 1mm off the top of a piece of 25mm wide STEEL and being fed faster than the one cutting the aluminium which as I said was being fed slowly due to the amount of cutter engagement on the internal curves and wanting to avoid the risk of chatter which did not occur.

The first cheap shell mill cutter I bought I was also very unhappy with, this is it and you can see by the work light that the whole machine is vibrating on the 0.5 and 1.0mm DOC cuts. If your leading edge is being pushe dup and not cutting then that will mean that the trailing edge will start to rub or take a light cut.




I found that the head was a slack fit on teh arbor so once that had been adjusted to run as true as possible and the included inserts replaced with name brand ones the thing was transformed.



This is with the better inserts starting with the same piece of cast iron and as you can see the 1mm cut does not faze it, then on steel and then with a change of inserts on aluminium.

[David]

How did you improve the fit of the shell mill to the arbor?

[jasonb]

Feb 9, 2020 9:34:04 GMT David said:

How did you improve the fit of the shell mill to the arbor?

Tapped it until it ran true then locked it up tight. Really need to do something more solid such as drill and tap for 3 equi spaced grub screws so there is no risk of a dig in moving the head on the arbor but I have used it several time since on iron castings and still true.

However the cheap Banggood one does not hold the inserts at quite the right angle so it can only be used for facing not machining an edge as it is off by a couple of degrees.

[Roger]

I think this all comes down to what someone thinks is noisy and what isn't. I've tried every permutation and combination of speeds and feeds, and it doesn't really make much difference, you always get that interrupted cut noise with indexable cutters. All that changes is the frequency of the drumming which only increases in intensity as you increase the feedrate.

I need to keep my activities almost silent because of the very close proximity of my neighbours and my need to machine commercially for extended periods. When casually asked by another neighbour who knows what I do, my nearest neighbour said he never hears anything. That's the way I need it to stay. If I can hear the mill from six feet outside of the garage door, it's too loud.
I very much doubt if that would be the case for the videos Jason has recorded. The noise of the spindle alone would probably be enough to be an issue. Most milling machines rattle, I know our old Bridgeport made an awful racket with the splines rattling against each other. Mine had a similar problem until I modified the quill to add a friction element to stop that form happening. I also added rubber mounts to the bottom of the mill so that any drumming isn't transmitted through the floor.

All of this may seem excessive, but a previous neighbour said he could hear something in his living room and asked if I'd got a compressor running or something. Not good!
Some people are lucky enough to be able to make a noise without any issues.

[millman]

Roger I have the same problem with noise as you do, the workshop is six feet away from the neighbours wall, things are ok during the day as we have a tyre fitting place opposite and they make a bit of noise but my problem has been the workshop compressor especially if I forget to turn it off at night, there is a slight leak somewhere in my pipe work and the damn thing starts up a couple of times in the night as the pressure drops. I have just invested in a Bambi silent compressor and this has solved the problem, the radio is now louder than the compressor is, still have to be careful not to do any hammering in the evenings though.

[Roger]

Feb 17, 2020 16:49:01 GMT millman said:

Roger I have the same problem with noise as you do, the workshop is six feet away from the neighbours wall, things are ok during the day as we have a tyre fitting place opposite and they make a bit of noise but my problem has been the workshop compressor especially if I forget to turn it off at night, there is a slight leak somewhere in my pipe work and the damn thing starts up a couple of times in the night as the pressure drops. I have just invested in a Bambi silent compressor and this has solved the problem, the radio is now louder than the compressor is, still have to be careful not to do any hammering in the evenings though.

Tricky isn't it! I only turn on the Hydrovane compressor when I need it, and that runs on a frequency converter so I only run it slowly. I guess you could put your compressor on a time switch so it can't run at night? Do you really need it on all the time anyway?
Things like hammering, sawing or using an angle grinder sometimes have to wait until I can see there are no cars in the drive next door, and then I can crack on.
Winter time is less of a problem because people have their windows closed and stormy weather masks some of the noise. Breathless Summer evenings can mean an early end to proceedings when you can hear a pin drop and all the windows are open.
Still, it also has its benefits in that I can work next to my Mill without ear plugs!

[jasonb]

Well with those restrictions you can only work within them.

As I have said several times that high frequency noise is not on the original videos and is something that creaps in when uploading and converting and alway hard to tell what level the sound is recorded at. Its really very quiet, my X3 with its gears in the head makes more noise at 1000rpm than the CNC at 5000rpm but in either case no need for ear protection. The compressor on the other hand is noisy.