Mills

Hi Terry, this is the paradox, I'm understanding that is should not be possible and the reasons why. However, I never saw him use any thing else but an end mill when he cut a keyway with this set up and he did not have any slot drills or otherwise for cutting closed keyways. The only other cutters were the side and face cutters used on the spindle between the machine and the support arm. These of course leave the curve of the cutter at each end of the keyway, and are used over the top of the work piece. All of the cutters belonged to the firm we worked for of course, but they were of his choice.

It's not recommended but you can plunge cut an end mill a few thou, then feed it along back and forth then plunge it a bit further. Or indeed plunge it at the same time as feeding it along the slot. Not good practice but it does work.

 

The reason slot drills don't cut oversize as much as endmills is because as one edge is cutting and deflecting the tool to the side, the other edge is trailing it 180 degrees in open space.  With an end mill, the tooth at the front doing the cutting deflects the cutter sideways while the next tooth which is (typically) only 90 degrees away, is in contact with the side of the slot making the slot wider.

Terry,

 

I agree that end mills are perfectly capable of cutting on the end. However, unless they are moving in Z, then all the cutting takes place with side flutes. I guess what I was trying to say is that they are somewhat mis-named. While they will cut on the end, that's not what you generally use them for. You'll have to be patient, I are an engineer, so naturally I struggle a bit with the English language, like what it is wrote.

 

I rather suspect that industry is moving away from end mills per se. Most of the 'end mills' I've bought recently are effectively three flute slot drills, even the roughers. I guess this has been driven by CNC requirements, where you need to enter the material at an angle, or a helical path in Z, in order to pocket out an enclosed area. Once at the correct depth you are essentially endmilling, but it helps to have a centre cut facility on the way in.

 

Regards,

 

Andrew

Hi Ian,

 

Thanks for the Thorp reference, I managed to get a copy from Amazon for £4.66 delivered. If anyone else is interested It seems a good buy.

 

Regards

 

Terry

All my solid carbide multi flute cutters are made that way, and any HSS end mills I buy are the same, even down to very small sizes.

 

 

 

 

 

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Hi Bogs

Although I am a moderator it is in name only. It is not part of my job to edit the website.

I only do it to help out, usually at evenings and weekends when everyone else is enjoying themselves.

I will in future delete what I think is required.

This thread has been tidied up.

regards david

 

 

Dear David,

 

Please make it clear to all that we Must not communicate personally or explain our feelings on the forum. 

 

We all have to be good little boys who does as the great master tells us and only comment on the exact theme of the thread.  Please make this clear in the rules and I'm sorry if I've upset anyone's delicate feelings. Poor things.

Hi Andrew,

 

How are your endmills? I've only managed to buy traditional ones, that's what seems to be sold mostly despite what I am hearing otherwise  Which type do YOU think Wolfie has?  Centre cut or traditional?

 

Do You buy them in Bedford? or elsewhere.

 

Terry

Hi David,

 

Could you please, please get together a list of 'how to's' and  'what not to do's' so that we can all understand and be good boys and girls instead of simply responding to the wishes of one or two others.

 

Terry

 

'I used to be paranoid but now I know they're out to get me'

Hi Wolfie,

 

One thing you have be careful of which has not been pointed out even by the 'experts' is that a 4 flute end mill will tend to wander and cut a slot oversize no matter how hard you try.  They should not really be used in this way, it is bad practice even though common.  This is especially the case in the example of the spiral flute milling cutters (as someone has shown elsewhere). You will usually get problems with those no matter how careful because of the way they cut in a slot and should not really be used for deep slot type cuts where they cut on both faces, they are designed for side cutting flat faces when cutting on one side only.  If you are cutting cavities that's ok though you can just get away with it as long as you take certain precautions.

 

The least problems will occur with with the straight flute 2 or three 3 flute slot drill.  This is because of the way they are designed.  If you need further clarification email me and I will send you a private message to explain as I am not allowed to contradict the 'experts' in public.

 

Terry

David,

 

I do wish you had left my post up there, just to explain why I brought up the subject.

 

Please delete the snide and childish remarks above if possible. Only then will this topic be of any use.

 

If you had left my post intact, then people would realise why I asked for them to be deleted.

 

It now seems that this site isn't for model engineers any more, as it is going just as I told you it would in my previous post (now deleted because you didn't like hearing the truth).

 

There are a few people who care very little about gaining or passing on knowledge, and just want to gossip and cause trouble when someone tells them to be good little boys and go to have their nappies changing,

 

I have seen them all over the years, take as much as they can, give nothing useful in return, and then destroy everything useful so no one else can enjoy it.

In fact, completely destroying the forum as it should be.

 

A very sad state of affairs.

 

Bogs

 

 

 

 

.

To get back to end mills.

 

Let me try to expain about end mills and slot drills. Many people have their own description of these but I'm afraid no one is right any longer - even me !!!
First off lets go back in history and see what we had. There were 4 flute end mills and 2 flute end mills. Some could plunge some couldn't. Confused? well you will be.
The two flute ones were called slot drills in the UK and were ground with one cutting edge over centre so they can plunge cut vertically down and then traverse, hence the name.
The 4 flute end mills usually had a hole in the centre for clearance when grinding and so can only cut on the sides of the tool. Trying to plunge with one of these will leave a central pip that will break the cutter when you try to traverse.
Now when we got towards the end of the 20th century things started changing. We had better methods of producing cutters with fancy 5 and 6 axis CNC grinders. We started to see 3 flute cutters getting popular as a compromise between rapid metal removal and chip clearance. We also started to get the 3 and 4 flute cutters with one lip ground over centre like the two flute . This means that these can also plunge.
To cap it all the manufacturers put paid to any standards by calling their cutters all sorts of different names. Where a 4 flute cutter was called an end mill it can now be centre cutting and be called a 4 flute slot drill.
If you look in any cutter catalogue nowdays you will find that they call a certain type of cutter by one name on one page and another manufacturer calls it by a different name on another page! The manufacturers have moved the goalposts. The cutter descriptions we all grew up with in Chapmans and Moultreich  has gone out the window with the advent of grinding techniques.
I took a 20mm solid carbide 4 flute end mill [ non centre cutting ] in for regrind last month and when it came back it was 4 flute over centre slot cutting cutter. What do I call this now?
The main thing to look for when buying cutters is the number of flutes you require and whether they are centre cutting or not.
I can see the time when the old 4 flute centre pipped type will become obsolete as most cutters are ground up from blank material nowdays.
I had a load of cam track slots to do the other week at 7.2mm wide. I had a choice of doing two passes with an undersized cutter or having a cutter ground down to 7.2mm

Hi All

 

What a shame yet another thread on this site is degenerating into back biting and bickering. What sort of example does set to anyone who is thinking of asking a question, especially those new to the discipline or even worse for the younger generation with an interest in engineering.

 

I would urge all parties to moderate their 'enthusiasm' , if indeed it can be classed as enthusiasm, when posting.

 

As far as I am concerned, as a rank beginner, there are people out there who are willing to help and share their knowledge for which I am thankful. If there is a bit of banter then fine provided the thread stays roughly on theme. However I find it disappointing when contributors let their egos/prejudices get the upper hand and start to insult or treat other members in a demeaning manner, as I said earlier it is NOT confined to this thread.

 

I know for a fact that in future I will take little interest in this site until the contributors show each other respect and are prepared to accept what others say without throwing their toys out of the pram.

 

At 7 years past retirement age I have little time to waste on point scoring and even less time to learn. Mechanical engineering for me, like others, has been a passion that I could only realise when I had the spare time and capital to invest i.e. after I retired.

 

I know this is OFF TOPIC but when I see this almost childish behaviour I see red.

 

 

Martin

 

Martin,

I'm afraid it's the same age old.

Those that can do it, do it.

Those that can't, teach it.

 

John S.

Hi Terry

I tidied up this thread at bogs request.

I also deleted bogs post, not because it bothered me but to see if it bothered him which it seemed to do.

I don't like deleting posts but do agree we should try to keep it slightly more on topic.

regards David

 

 

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Posted By Bogstandard on 29/11/2010 18:15:20.

Hi, I think these complaints about thread post content are contradictory in themseves as they are also off topic, are they not. Espceialy long winded and detailed ones. Should you not open a new thread titled post content complaint, or somthing.

Hi Wolfy, Ive just been churning thru' this topic. However I Suspect you are like me, with one or two "won" mills. True they wont cut accurate slots, if for a key-way it might be better to just cut and then make a key to suit. Best cheap way to hold them is to buy a soft ended Morse taper mandrel, fit a draw bar, drill end to size, in two goes for accuracy, tap for holding screw, grind flat on mill shank for holding if needed. I expect to get shot down, but that's what I've done, and it works, and cheap ,relatively.

Hi, Gordon and wolfy, I've done similar things, so I might get shot down as well. The thing is if it works and is simple and safe, then what does it matter.