Turning, Milling and Drilling Speeds

Hi all,

I would like to print out and laminate a simple table to show turning, milling and drilling speeds, for common materials. Can anyone point me to one?

Thanks

google it you will be spoilt for chose

LMS has milling, turning and drilling calculators (imperial units) that I find useful. If you want feeds for milling and also metric units, LMS has this calculator. If you do a web search you should find many tables that you could print:

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Thor

Turning, milling and drilling speeds are all about the speed relationship between the tool and the workpiece. For milling you also need to understand feed rates to ensure the tool is cutting and not rubbing. There are a number of threads in the forum that cover this and will have links to follow.

Martin C

William, beware that cutting speed tables are based on some important assumptions, but these assumptions may not be obvious. For example, most accessible tables are prepared for industrial use, where machines are more powerful and more rigid, and flooded with cutting fluid, compared to typical garden shed inhabitants. Also, the speeds may be those likely to maximise production, with 'reasonable' tool life (whatever that means), whereas we usually want to be gentler and don't mind taking more time. One could go on, but, in reality, on 'our' machines, what works best is best, and speeds and feeds can't be transferred from one machine and setup to another with any confidence. Use tables prepared for 'us' (The Model Engineer's Handbook, by Tubal Cain [not the dubious American upstart]) as a guide, but don't be afraid to experiment and break 'rules'. And once one starts to use 'exotic' cutting materials, it's a whole new ball game...

So googling for charts is a waste of time for a newbie as we would not know if the chart is for industrial machines. I have the model engineers handbook and do refer to that for many things.

I have just finished tramming my new mill and getting the vice set correctly so will be starting to have a few test cuts on some hot rolled steel until I take delivery of some decent metal which I need to decide what the simple first project will be. I don't want to just buy metal willy nilly and then find I have no use for it

+1 on Tubal Cain's "The Model Engineers Handbook". He doesn't just throw the numbers out there but explains why they vary from those in industrial use.

Brian G

I did that, but there are so many and I have no idea which ones are correct (e.g. put up by someone who knows what they are talking about and someone who neccessarily does not).

An excellent analysis of the situation, William

[ Martin’s suggestion backfires, I regret to say ]

MichaelG.

William / Derek - when I began machining at home I had absolutely no concept of cutting speeds or feeds. I think I may have mentioned before I watched with rapidly increasing alarm as the tool began to glow red hot when trying to machine a Stuart Compound cylinder block. This was circa 1972/3. Trying to cut a thread on silver steel was also an eye opening experience!

Around 1980 I trained as a milling machinist and the first thing I learnt about was the cutting speeds of various metals - it really was a 'light going on moment'. No 'charts' were provided but a basic list of average cutting speeds to work from.

Though I have several companies reference booklets collected at work over the years they are never referred to - I still work either side of the parameters of that list with a simple calculation

RPM = Cutting Speed x 4 / Diameter of Cutter which is a simplification of Cutting Speed x 12/Diameter of Cutter x Pi

The list is based on using HSS tooling and works either way from Mild Steel which has a basic speed of 100 ft per min. eg a 1/2" cutter on MS is average 800 rpm.

That's a ball park figure from which to work either side of depending on the actual steel being machined and machine capabilities.

Here's an image from the little pocket book I wrote down in 1980 - I still have it and it still sees occasional use to this day

The only time I have ever had need to adhere to manufacturers specified speeds and feed information was when using carbides tooling on large machines and on a CNC machining centre - to me, for ME home use, these simply mislead the average guy at home with limited experience to call on.

The above has served me well for over 40 odd years. It's basic but it works - hope it's of use to you too

Tug

Edited By Ramon Wilson on 03/10/2021 12:06:29

I use the simple approximation rpm = 10000 divided by diameter in mm to get into the right ball-park for HSS.

It's correct for most Cast Irons, Mild Steel, Bronze, Phosphor-bronze, hardened Copper, and Gunmetal and can be adjusted for other materials as follows:

• Quarter the speed when cutting chilled cast-iron and for getting through the nasty hard skin ordinary cast iron sometimes has.
• Halve the RPM when cutting Cast, Stainless, High Tensile or Silver Steel
• Increase speed by 75% when cutting Brass or Free-Cutting Mild-steel
• Double the speed to cut Aluminium.

RPM also depends on the cutter. After the above:

• Reduce speed by ⅔ if the cutter is tool-steel or hardened silver-steel
• Reduce speed by ¾ if parting off or using a form tool
• Triple the speed if the cutter is carbide

Don't take RPM too seriously! Much depends on the machine, operator, particular alloy being cut and other factors, and it may be impossible to get older machines spinning fast enough to cut Aluminium with Carbide optimally. My advice is to start with the estimate and adjust as necessary. Many metals are quite forgiving and will cut well enough over a wide range of speeds. Others are downright fussy, which is why I don't recommend learning on unknown scrap! Adjust speed If finish is poor, or the lathe sounds stressed, but also experiment with depth-of-cut and feed-rate, which are equally important. Don't scratch at work or hack into it. I fine tune cuts by eye-balling the finish and listening to the lathe - it should be audibly working but not labouring.

Dave

PM me with an E mail address and I'll dig out my training notes from 1958, at Sentinel, R-R Oil Engine Division, copy them and send them to you. They won't cover carbides.

They may be still be applicable, certainly a good starting point, to start experimenting.. Things may differ from one machine to another. What works well on a Warco BH600, may not work as well on a Myford ML4!

You can also have a table showing feed per tooth for Milling cutters, if it will help.

The sharpness or otherwise of tools will have an effect, though.

Grinding the tool to the right geometry will have a big effect on surface finish.

Replaceable Carbide tips will have the right geometry, but the holder will need to be correct as well to ensure that the cutting tip IS at the correct angle to the workpiece.

Older machines may not be sufficiently rigid, or fast enough to obtain the best results from Carbides, which were developed for heavy, fast, rigid Industrial machinery.

Howard.

If you have an iPhone there is FS Wizard or FS Wizard Pro that you can download. Don't know about Android phones.