How to choose a high quality end mill cutter?

[David HoggParticipant @davidhogg58185]

[David HoggParticipant @davidhogg58185]

Hi all 🙂

I’m slowly starting to use my Axminster SX1 / Sieg X1 micro mill and currently i have a set of Proxxon end mills … but I understand, like with all things, you get what you pay for, and more expensive cutters will cut cleaner, can take heavier cuts and will last longer … my current ones were about £50 for 4 different sizes … so pretty cheap!

I’m happy to invest in a higher quality end mill, especially as I find I’ve only ever used one size so far (10mm) … but there are SO many to choose from!

I’ll mainly be working in aluminium, but want to have the ability to work in other metals too in the future … Cutwel seem to have an amazing range but I’ve got no idea where to start!

**LINK**

Quinn of the YouTube channel Blondihacks (who has basically taught me everything I know so far about milling and is a great tutor) advises against Carbide tools which most small hobbyist machines aren’t able to push hard enough for them to work properly (?), so I guess that rules those types out, but there are still hundreds more to choose from!

Any pointers or advice you can give would be much appreciated.

Many thanks,

David 🙂

[Peter Cook 6Participant @petercook6]

My cutters of choice for my SX1LP are the HSS 8% Cobalt cutters from shop-apt.co.uk. I use their 2 flute uncoated on Aluminium and 3 flute coated on steel. Very sharp, and cut just fine if you keep the speeds up – just don't think about the speeds APT quote ( 7000rpm for a 6mm cutter in aluminium!)

[Martin ConnellyParticipant @martinconnelly55370]

Peter said he uses uncoated cutters, I would go further and say do not use coated cutters, you need cutters with a nice polished finish for aluminium to avoid the metal sticking to the cutter.

Martin C

[Paul LousickParticipant @paullousick59116]

Yes, It's good to invest in good quality cutters and drills but twist drills can be sharpened on a simple grinding wheel. End mills need a special grinder to re-sharpen, which I don't have and use the less expensive ones. I have a couple of preferred sellers who I buy from and therefore have an idea of the quality supplied.

[JasonBModerator @jasonb]

There is no real reason not to use carbide on the lighter hobby machines if treated with care, my go to cutter for aluminium and non ferrous on the manual mill is a 10mm 2-flute aluminium specific one from ARC, keeps it sharp edge a lot longer than HSS. Carbide can also be run faster and or take a heavier cut than HSS so you get the job done a bit faster.

I also use quite a few HSS FC-3 cutters by Hertel, you can get these from MSC but flute length can be a bit limiting. So for longer the HSS or Carbide from APT work out quite reasonable price wise. For Aluminium I'd go with their 3-flute uncoated carbide and steel the coated 3-flute carbide or HSS which is what I mostly use on the CNC but they do find their way onto the manual mills more lately. I also get a fair amount of use from the NC (New Century) ones that Cutwel do in the 3-flute coated carbide for steel and CI. New Century is YH-1's factory in China but like the other ones mentioned above they are all a cut above the basic cheap cutters but not as pricy as the very high performance ones.

Good video that shows how much more a carbide cutter can remove compared to an HSS one run at the same speeds.

[JasonBModerator @jasonb]

On the question of coated or uncoated on aluminium in most cases I would say uncoated but there are a couple of exceptions.

Firstly you can get coatings specifically on tools with aluminium cutting geometry such as DLC but on a manual machine it may not be worth the couple of quid more per cutter.

Secondly you may want a specific cutter and find it is not available in uncoated or simply not want to buy an uncoated for a single use. In these cases just take care and use plenty of lubrication such as paraffin or WD40 and a reduced feed rate and/or depth of cut to help stop material build up on the cutting edges.

[Ron LadenParticipant @ronladen17547]

I tend to use mostly carbide cutters on my SX2P most of which I get from ARC, 2 flute uncoated for aluminium and coated types for steel. As Jason says they are Chinese but of better quality than the cheapies you see advertised, I know some swear by the cheap cutters and inserts that you can find but that has not been my experience. Also there is no need to go for the really expensive ones for use on a small mill, all the mid priced ones I have used have given good results and decent tool life.

[Thor 🇳🇴Participant @thor]

Hi David,

I too use HSS Cobalt cutters on my milling machine. If you want good cutters and don't mind the price I would say Dormer or other brand name cutters. I have also used the cutters from ARC that Jason mentioned and they work well. After I made a toolgrinder to grind the cutting teeth on my endmills and slotdrills I have used cheaper unbranded cutters made in Asia. Carbide cutters are used to remove the hard skin on castings or when working on hot rolled stell.

Thor

[David HoggParticipant @davidhogg58185]

Wow thank you so much for your replies everyone 🙂

I suppose it’s like asking what is the best type of shoe to buy — everyone will probably say something different and there’s no wrong or right answer 😄

My machine has a maximum speed of 2000rpm, and with my very rough understanding of speeds and feeds, I think I need at least a 4 flute 10mm cutter to be able to cut at a reasonable feed speed, which I guess helps eliminate some of the lower flute count options?

Also because of my mill’s small size, it probably doesn’t have the power to take off the large amounts of material that carbide tools excel at, and hence perhaps carbide tools are unnecessary for my setup? Although on the flip side, as they’ll never be pushed hard, their increased hardness will probably mean they’ll still outlast HSS cutters with no real disadvantages?

The only reason I’m thinking of getting a better end mill, is that even at a very slow cutting speed and shallow cutting depth when using the side of the end mill, the surface finish when conventional milling is poor, and Quinn has suggested this might be because of a poor quality end mill — I currently have a set of these:

https://www.axminstertools.com/proxxon-4-piece-milling-cutter-set-6-10mm-474927?glCountry=GB&glCurrency=GBP

Apparently these are HSS-Co5 according to Proxxon’s website.

Finishing passes when climb milling gives a lovely shiny surface finish.

Quinn’s advice was that it’s not worth buying cheap cutters and to spend as much as I can afford on good quality cutters … but it sounds like this isn’t necessarily the case? I’m really not doing much work on my machine, but it would be nice to know I’ve got a good quality set of cutters to start with.

It’s sounding like uncoated 4 flute HSS-Co8 or carbide tools would be just fine? I’ve seen some of these for as low as £10 which just feels too cheap!

Thanks again for your help!

David

[Anonymous]

I disagree with Blondihacks on a lot of things, including not using carbide cutters on hobby mills. Carbide cutters work just fine on smaller mills. There is one caveat though; there is no point in paying for fancy coatings as they often require high temperatures, meaning high speeds and feedrates, to provide any benefit. I would agree with Blondihacks on not buying cheap cutters. There are two rules for buying cutters:

1. Don't waste money on cheap cutters

2. See rule 1

Cheap cutters are often poorly ground and it is difficult, or impossible, to get a good finish. Also note that carbide is not a homogeneous material; it consists of carbide particles in a binder material, often cobalt. Cheaper cutters tend to have less carbide.

I use K2 cutters from Cutwel for most machining, and their Alu-Power HPC cutters for aluminium. I also use the premium range from Arc and have found them to be excellent.

Using a 4-flute cutter for aluminium is not a good idea. Since aluminium is soft one can use a high feedrate with a large chip load. The problem then becomes one of getting rid of the swarf. With 4 flutes the gullet is small and the swarf can 'weld' to the cutter, like this:

Traditionally 2-flute cutters were used for aluminium, but 3-flute are more common now. Aluminium specific cutters are highly polished as this helps prevent the swarf from clogging the cutter. Flood coolant also helps, but I assume this is not available. Alternatively a squirt of WD40 can help.

Andrew

[Y C LuiParticipant @yclui16187]

Posted by David Hogg on 29/03/2022 09:02:28:

It’s sounding like uncoated 4 flute HSS-Co8 or carbide tools would be just fine? I’ve seen some of these for as low as £10 which just feels too cheap!

I bought all my tools from China and £10 is way too expensive. Just ordered a 10 mm Co8 HSS end mill and it cost just 20 Chinese Yuan or about £2.4. All my other tools are carbide. A 10 mm carbide 3 fluter cost about £5. Globalization is one of the reason why there has not been much inflation over the last decade ( pre COVID 19 ) although governments have been printing money like crazy.

Edited By Y C Lui on 29/03/2022 09:36:17

[VicParticipant @vic]

Have a look at Rennie Tools offerings David. I’ve been well pleased with the price, quality and service. You can buy from them direct or through Amazon.

[Clive FosterParticipant @clivefoster55965]

As has been said step one is to get a reliable brand. I tend to buy mid range industrial ones as my machine is a Bridgeport.

Step two is to make best use of what you have bought within the limitations of the machine. My Bridgeport is a monster compared to your X1 but its still only specced for endmills up to 1" diameter!

There is much more to be gained by setting into a proper technique to get longest life than by stumping up the extra ££ for a super duper extra quality cutter costs over decent mid range.

Coatings are generally thermally sensitive and usually need to get hot to work properly. No point in paying the extra if you aren't going to see any real benefit because your machine cannot work them hard enough to heat up. However even if the coating doesn't get into working range the cutter may still last a little longer but this is usually more due to the base cutter being of higher quality than a simple mid range one. If a good maker is going to go to the trouble of coating it makes sense to start with a high quality cutter.

If buying off brand a certain care and feel for prices is needed to avoid the low end cutters dressed up with a pretty coating for showroom appeal. Rather like the pretty TiN coated drill sets in the bargain bin.

Normally too messy for us but decently arranged coolant, either mist or flood, is probably the best way of extending cutter life. On my Bridgeport decent but inexpensive with mist is about the equal of good (mid range industrial) dry for lifetime.

The big neophyte error is babying the cutter with tiny cuts rather than letting it cut. For best results and life you need to get close to book values. Oh and use the sides, book says depth same as diameter at 1/4 diameter width for endmilling and 1/2 diameter depth for slots so get as close as you can given the job and machine specifications. I can just follow the book, you will need to be more circumspect with larger cutters.

Fundamentally the cutter lifetime is defined in number of turns and number of passes. Crudely twice as many passes at half the feed means 1/4 as many jobs per cutter. Keep the chips clear, recutting chips still counts and conditions are unfavourable.

Don't go mad as you are machine stiffness limited but it's well worth sacrificing a cutter or three just to get a good handle on what works for you. When you have found out the best settings, whether by experiment or inadvertently mid job write them down.

The advice against carbide cutters is primarily against the insert kind. Generally the holder diameters are too large and the inserts designed for heavier cuts at higher speeds than your X1 likes. But, as with lathe tooling, there are a fair number of inserts that work fine in lighter machines at well below book speeds and cuts. There are also some that will leave a ploughed field finish if used off book. Experimentation is expensive!

Normal endmills in carbide will be fine. Handle with care as they are very sharp. They don't like vibration which can lead to edge chipping. Given the much greater durability of the sharp edge relative to HSS this is the one time where going light on cuts may be an advantage with a small machine which doesn't have the mass to tamp down vibration.

Carbide shanks are "more slippery" than steel ones so they don't hold as well in collets. Collet needs to be pulled up well. ER are better than Morse or 5C but you should use book torques. Don't even think about bodging one into a drill chuck to save changing the chuck out. It will walk straight out under cut! Learned that the hard way many years ago when I "only wanted a quick counterbore" on a drilled hole. My carbides are weldon flat types.

Clive

PS Sorry for repeating some previous advice. Slow typing. + 1 Andrews recommendation for Cutwel, a very good supplier.

Edited By Clive Foster on 29/03/2022 10:13:58

[JasonBModerator @jasonb]

One thing with the aluminium specific cutters which do work better than standard geometry is that they tend to have less flutes so that the cutter can clear the larger volume of swarf, 3-flute would be the most you could get so feed rate would be a little less than a 4-flute but the sharper edge and geometry allows a deeper cut so all in all not much difference.

In a similar vein it is harder to find uncoated 4-flute cutters as they tend to be used on steels and iron so not ideal for your mostly aluminium use.

It would probably be best if funds allow to buy separate cutters for the two metal groups as the aluminium and non ferrous ones will stay sharper for longer if restricted to those metals and have some coated ones to keep for when you want to work steel and iron

I was just looking and that 2-flute cutter I mentioned came as part of the tooling sent to go with my beginners milling articles in MEW, here it is on the SX2.7 in 2017 giving a good finish with conventional direction cutting, full passes 16mm high and probably 1mm stepover.

Same cutter after a lot of use just on ali and non ferrious a couple of weeks ago still peeling off long ribbons of swarf, similar 16mm high x 1mm stepover on a mill with 2000max spindle. So not bad for 5 years and 20 odd engines, I did buy another but have not had the need to start using it yet.

ARC don't do a 3-flute ali one so something like this would allow you to feed a bit faster, or the slightly more expensive one like this

Edited By JasonB on 29/03/2022 10:21:52

[John PParticipant @johnp77052]

I buy end mills now from Ali******s as seen here in the photo,
the 4 mm are about £1 each and the 6 mm £2 each
delivered ,they are most probably the best cutters i have ever
bought .

At least one of the suppliers mentioned on this thread
had supplied me with cutters in the past that were blunt,
after an exchange of words with the proprietor he actually
admitted that he knew of the problem and came out with
the old excuse lots have others have had them and not
complained .I sent them back and was refunded i only wish
that i had sent back the supposedly ball end mills as well
as the were also rubbish.

These Ali******s mills are carbide TiAIN coated and most
on here would call them cheap cutters ,perhaps it would
be as well to remember that all of the cutters that you
buy over here are most probably also made in China.

John

[Henry BrownParticipant @henrybrown95529]

One thing worth noting is that an unknown grade aluminium may not give a particularly good finish whatever the cutter.

My mill only runs to 1600 rpm, I find I get very acceptable finishes using any reasonable quality cutters, I do tend to look for industrial types on clearance – metric or imperial, I'm not fussy!

I've found that climb milling is the best way to get a good finish when using the side of the cutter. As I don't use flood cooling I don't always lubricate the cutter for aluminium, if I do I use WD40 because that is handy, I don't have any other use for paraffin.

[Ron LadenParticipant @ronladen17547]

Dont be put off and think that carbide cutters are not suited to your SX1 as I mentioned most of the cutters I use on the SX2 are carbide and that is also a small hobby mill. I also use the ARC 10mm Carbide 2 flute uncoated cutter (as Jason shows) and mine is still good after 3 years. The thing to remember is your mill is a small hobby machine so dont ask it to bite off more than it can chew take it easy to start with and put in some practice. Also I would suggest not getting hung up on what the books tell you re feeds and depths of cut etc. You will soon find that the machine and the cutter and the finish will tell you what its happy with .

[Anonymous]

Posted by Clive Foster on 29/03/2022 10:09:06:

The big neophyte error is babying the cutter with tiny cuts rather than letting it cut. For best results and life you need to get close to book values.

Agreed; pussyfooting around just means that the cutter tends to rub rather than cut, especially with conventional milling. Consider the following:

*** Cutters are consumable items, they wear out and need to be replaced ***

Andrew

[Tony Pratt 1Participant @tonypratt1]

I find Drill Services is another good UK supplier.

Tony

[Dave SParticipant @daves59043]

MSC often have reasonable endmills in their monthly Advantage flyers.

Carbide is an oft abused term… In days of yore carbides had relatively large grain sizes and negative geometry was the order of the day. These cutters are indeed not ideal for lighter weight/lower rigidity machines. They’re also not usual in 10mm or less diameter.

Compare with today’s solid carbide micro grain mills – super sharp, stiffer than HSS and not unreasonable in price.

I would have no qualms about using solid micro grain carbide on a light mill – that’s pretty much all I run on the proxxon.

I tend to use a mix of HSS, insert and solid carbide, mostly depending on what size I need on the other mill. My mill is big and heavy, but apart from the insert stuff ( which tends to be larger) the mills are generally held in ER16 collets, so of the size a SX2 would use.

Dave

[SillyOldDufferModerator @sillyoldduffer]

Welcome to the forum David.

I dislike the word 'quality' in engineering because it's meaningless without a specification. Cutting metal is a science. Professional tool catalogues don't mention quality at all. Cutters are chosen to optimise an economic work-rate. A huge range of cutters are available to meet production needs from inexpensive disposables to extremely costly items made to cope with difficult materials. Professionals try to define Value for Money and Fit for Purpose. They don't waste cash on expensive tools or buy brands recommended by a bloke on the internet!

At home metal cutting is more art than science and many Model Engineers are self-taught: I still wish we would avoid the 'Q' word.

Four things cause machining bother: the material, machine, cutter, and operator error:

• Avoid scrap! Instead, buy metal where the spec mentions 'free-cutting' or 'Good Machinability'. Makes a big difference, ordinary mild-steel is prone to smear, making it difficult to get a good finish. Work-hardening stainless ruins cutters in a blink. Leaded mild-steel is much better!
• All machines have an envelope within which they work well. Determined by size, rigidity, power, and whatever features it has. Easier for operators to get results with a heavy, rigid, powerful industrial machine with all the bells and whistles than a small lightweight basic hobby-machine but, with practice and patience, hobby machines do just as well.
• Cutters are chosen to suit the job and the machine. I own a WM18, 1100W out, max speed 2500rpm. It's not fast, rigid, or powerful enough to get the best out of carbide so I have only two carbide cutters, a 4-flute 10mm used for roughing out steel, and an insert boring tool. Otherwise, all my milling cutters are mid-range HSS bought from established UK hobby suppliers, who usually respond well if they happen to sell a dud. I have both 2 and 4 flute cutters. 2 flute are for plunge cutting and slotting. For other cuts, 4 flutes remove metal faster. I avoid internet and exhibitions 'bargains', because they're anything between top-end surplus to cheap and nasty. Too cheap is one way of conning customers, another is reassuringly expensive! Fewer tears when a mid-range tool is ruined and the money saved can be spent on something else. When better tools are needed I cough up, but not before.
• Many problems are caused by the operator! David mentions poor finish 'even at a very slow cutting speed and shallow cutting depth'. Unfortunately slow, shallow cutting is an excellent way of blunting cutters, ruining them. Don't do it. Tools should cut, not rub, requiring the operator to get RPM, depth-of-cut, and feed-rate about right. Pussy-footing and over-heavy cutting are both sins, the first because it blunts tools, the other because it cooks the motor, stresses the drive-train and bends the machine. Mincing swarf under cutters also blunts them quickly. Lubrication improves finish and tool-life. Messy flood cooling extends tool-life considerably, but is only worth it, I think, when removing lots of metal quickly.

Tools didn't stay sharp long when I was learning – poor technique. I could have wasted a lot of money ruining expensive cutters! Instead, I practised on mid-range and found they last when used properly. I start with RPM = 10000/tool diameter in mm (about right for mild-steel), cut-depth a bit under 20% of tool diameter, and feed-rate increased until the machine is heard working moderately hard, not labouring.

HSS is often coated with a layer of extra-hard material to keep them sharp about 15% longer. Aluminium tends to stick to the coating, so uncoated is a better choice for it. I use TiN coated HSS for everything, but take care aluminium doesn't stick to the cutter because it wastes time.

Not much of the above depends on 'quality'. More to do with the operator understanding how his particular machine relates to the materials he works with and the required finish and accuracy. Rather than buy expensive high-performance tools that aren't needed, I buy mid-range and go up market only if they're not good enough.

In the good old days, cheap tools were rubbish and it paid apprentice craftsmen to buy the best they could afford and make it last. Not how the modern world works. Now tools are expected to do a job for a reasonable amount of time, and are then replaced. What's meant by a 'reasonable amount of time' is specified, allowing cheaper tools to be used when long lasting tools aren't necessary. Or money to be begged/ borrowed/stolen when only the best will do! How long your tools should last needs thought. A sad feature of the forum is relatives selling off workshops full of tools that lasted longer than the late lamented Model Engineer.

How best to self-teach is tricky. I like books and magazines – not for everyone. Much of the Workshop Practice Series is excellent except modern stuff like carbide and DROs are missing. Jason Ballamy's book is up-to-date. I've found the forum excellent because it allows question and answer.

Be wary of Internet videos. Often an inglorious mix of good and bad in the same clip, together with product placement, misunderstandings and duff opinions.

Dave

[Dave SParticipant @daves59043]

Posted by SillyOldDuffer on 29/03/2022 13:36:09:

Be wary of Internet videos. Often an inglorious mix of good and bad in the same clip, together with product placement, misunderstandings and duff opinions.

Nicely put

Dave

[Mick B1Participant @mickb1]

I make components of smallish size and I'm not really interested in cubic inches per minute metal removal.

I do practically all my milling in the lathe (Warco WM250V) with a Myford double-swivel milling slide.

If I'm cutting steps and flats I use an 8 mm 4-flute carbide endmill – I've had it at least 6 years and I think it cost me 12 quid from Gloster Tooling. It's still sharp and produces a decent finish on anything I've tried it on – silver steel, titanium, ali, brass, phosphor bronze, several kinds of hardwood.

Flycutting for larger flats uses a standard 3/8 or 1/2" boring bar with a 3/16" 45 degree HSS toolbit. So long as it's sharp, it producesa a silky finish.

For slots I use a 2-flute HSS or carbide slot drill – I've got several sizes and none were expensive.

Some times I do parts for the railway and milling is mostly cutting hexagons in a divvy head on a Bridgeport. There's a 2" diameter 5-insert face mill I usually use if I can find it. There's sometimes a fair bit of metal removal to do there, but then it really isn't model engineering…

Edited By Mick B1 on 29/03/2022 16:29:36

[David HoggParticipant @davidhogg58185]

Wow thank you all so much for your time and advice, it's hugely appreciated 🙂

I think I'll start by spending some time finding out what the limits of my current setup are before I start buying more things (I did enough of that when I first bought the machine 😆! ).

Not 'pussy footing' or taking cuts that are too light needs some getting used to! In all other forms of craftsmanship I've experienced it's always been that you can never be too gentle with tools / machines … but here it seems it's actually detrimental to the tool to be too gentle!

I certainly hear what you're saying about internet videos, and there's definitely a huge variety out there, from great to really poor … although that said, I'm sure you also get a variety in the quality of books depending on who's written them, although the variation probably isn't as pronounced.

I think the Blondihacks tutorial videos I've been following deserve credit, with many of the comments left under the videos saying how Quinn has a knack for explaining techniques in a very clear and logical way, with some machining professors even advising their students to use her videos as a great starter for their courses.

Still, I'm happy to accept that no tutorial / guide is perfect, whether it's a video or a book, and that nothing can replace learning things (and making mistakes 🙈! ) hands-on. Still, between Blondihacks and this forum, I feel very well supported in my journey into milling land! 🙂

Thanks again!

David

Edited By David Hogg on 29/03/2022 22:38:10

[Author]

Posts