Milling Cutters for the Novice

[Martin CurrieParticipant @martincurrie]

Hello everyone

I'm completely new to milling and have recently bought myself a secondhand Chester Champion 20VS mill. I noticed that this mill was the same as the G0704 made by Grizzly and I have ordered from the US, a belt conversion for this mill along with replacement bearings for the belt drive and also the spindle. I bought SKF bearings which are high end quality and I'm looking forward to making these mods to the mill.

As mentioned above I'm new to milling and I'd be grateful if someone could point me in the direction of a good quality milling cutters. I'm hoping to start building model steam engine kits going forward and if i can a locomotive too.

I know nothing about milling cutters other than what I've seen online any advice would be most welcome. I'll be using either a ER40 or 32 collett system to hold these cutters and this will be great for my GH1230 lathe that I've just bought.

Any tips pointers, advice would be greatly appreciated.

Martin

[Martin CurrieParticipant @martincurrie]

[Brian HParticipant @brianh50089]

Hello Martin, the basic thing with milling cutters in a vertical mill is whether you cut from one side as in cutting a step, in which case use an end mill or, if you need to plunge in to cut a closed end slot then use a slot drill.

Both types come in HSS or tungsten but HSS will be fine for most work in a small workshop. Cutting speeds follow the standard rates for lathe use but need to be multiplied by the number of teeth on the cutter, but in practice the speed and feed rates need to be what sound right for the machine.

Brian

[JasonBModerator @jasonb]

The above may have been true at one time but with modern cutters being available with "end cutting" geometry then you can plunge with most flute numbers.

With that in mind I would suggest a good starting point will be some HSS FC-3 cutters often known as "Disposable" but don't worry about that now. These are a good all rounder to get started with and then you can add more cutters for specific uses as you find the need.

Avoid super cheap as quality can vary but mid range from a reputable supplier will be fine and the FC-3s are not expensive anyway. Something like these from APT or the ones MSC do will be fine

[JourneymanParticipant @journeyman]

If, as you say, you are completely new to milling. You would probably benefit from Jason's book ** Milling for Beginners **

John

[egaParticipant @ega]

JasonB:

Do you find that you can safely grip the Weldon cutters in a conventional collet?

Edited By ega on 31/03/2021 09:12:59

[JasonBModerator @jasonb]

99% of the time I use ER and have no problems. The few times head room has been an issue then MT collets have worked OK.

Some Weldon type holders do have the grub screw hole a bit too far up for the very small diameters so you end up with the flutes inside the holder unless you grind an extra flat.

The APT ones are a bit longer in the shank than the Hertel ones that MSC sell

[Brian HParticipant @brianh50089]

Martin, I'm sure that Jason is absolutely correct about modern cutters, most of mine are very old, kept going by the occasional regrind.

Please don't be put off by the terms 'Disposable' or 'Throw-away', There is nothing wrong with these cutters, it is simply that, in industry, it is not financially worth resharpening them, it is cheaper to get get a new one.

Brian

[SillyOldDufferModerator @sillyoldduffer]

Mid-range is my watchword too! Beware chasing 'good quality' anything, because unless you're doing something special, the best is probably far more expensive than you need, and the costly quality could be useless, such as cutters carefully balanced to spin at 30000rpm, which is far beyond the ability of a 20VS.

I guess by 'good quality' you mean, 'lasts a reasonable amount of time before going blunt, not too easily bent, and I prefer not to put my daughters on the game to pay for it'. If so, see Jason's advice,

'Quality' and 'Disposable' both have ordinary English meanings likely to mislead in engineering. Jason's disposable cutters aren't disposable in the sense of being cheap and nasty, it's just that they aren't made to be resharpened. Which is fine for the average home workshop because hardly anyone has the kit needed to sharpen milling cutters. Disposables are popular in industry too, because you have to resharpen thousands of cutters to recover the cost of a suitable grinding machine, and below a certain level it's not worth the bother.

I bought an ordinary set of 2 and 4 flute TiN coated HSS cutters with my mill. They're neither Cheesium or sooper-dooper. With hindsight, I could have saved a few quid by only buying the sizes I actually use, and probably all of the 3-flute type! Though I eventually broke both 2 and 4mm cutters due to over-enthusiasm, all the others are still cutting fine. However, I use a 10mm solid carbide cutter for roughing out whenever possible, a fly cutter for flattening, and try to even wear out across the set, and the flutes. Apart from the Carbide cutter, there are a few other 'specials; the most common are uncoated disposables bought for Aluminium,

Dave

[JasonBModerator @jasonb]

Further to my mention of some FC3 cutters being a bit short for sidelock holders here is a piccy for you

From left to right Dormer, Hertel, APT, ARC though ARC are not solde as FC3 "disposable" type

You can see the Dormer and hertel are quite short and if their flat were used in the holder shown they would not project out the end. The APT is OK as is the ARC one though in the smaller sizes the ARC Premium range are not quite so competttive but worth looking at over 10mm and if you are ordering other items then one or two added to the order won't incur the same postage costs as putting in a second order to another supplier

[JasonBModerator @jasonb]

Posted by ?

Cutting speeds follow the standard rates for lathe use but need to be multiplied by the number of teeth on the cutter, but in practice the speed and feed rates need to be what sound right for the machine.

Just to save you cooking your newly purchased cutters. Cutting speeds (rpm) are mostly governed by material, cutter diameter and cutter material not the number of cutting edges or flutes.

Feed rate (how fast the work is advanced into the cutter) is related to the number of flutes, basically work out how much you want each cutting edge to remove as it contacts the work known as chip load and then multipy by the number of flutes then by rpm.

[egaParticipant @ega]

JasonB:

Many thanks for your response.

Incidentally, the Weldon holder obviously works in practice but seems inferior in principle to the contracting collet. The Rotabroach system uses two flats at 90 degrees to each other which again seems preferable to the Weldon.

[Martin CurrieParticipant @martincurrie]

Guys

Thank you all very much for these informative replies to my question on cutters, I'll have a look into ARC, APT's website. I had sent APT an email about two weeks ago, but yet to get a reply.

I'll get myself an ER40 collet system, I've decided on the 40's and this will work well alongside my lathe also.

Thanks once again

Martin

[Dave WoottonParticipant @davewootton]

Martin

I can't add anything to the very good advice given above, but if you do need a reference for cutter speeds and feeds the one in Tubal Cains's book "The model engineers handbook" a is very good guide. Mine of other information too.

Happy Milling

Dave

[noel shelleyParticipant @noelshelley55608]

The book mentioned above is always at my right hand, along with " the metalworkers Data book ! No 42 By Harold Hall.

The Rotabroach system and it's Weldon shank – 2 grub screws, is this type of holding always refered to as a weldon shank ?

Good luck. Noel.

[JasonBModerator @jasonb]

I think Weldon is a bit like Hoover and gets used to describe a lot of cutters and holders which are sidelock. Originated from when Weldon were the first to invent helical fluted cutters, the older ones having straight flutes and the flat on the side was added to stop the tendency of the helix to pull the cutter out of the holder

[colin vercoeParticipant @colinvercoe57719]

I would go for three flute cutters as a general all round cutter as they can be used as an end mill and a slot drill and give great results for both operations.

Colin

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