Finally got the milling machine home.

So can I ask in the order of strength. Which is the weekest to strongest. I.E I take it R8 is stronger than MT2 but what above that, MT3 etc ?????? +all the old sizes .

Steve.

I believe the strength will increase as volume of metal increases because of greater diameter but that increase will depend on the quality of metal being used, not much point in a toolholder made of poor quality material.

For a small increase in diameter you will get considerably more stiffness.

Emgee

The question is meaningless as is. Are you talking about relative strength of holding the cutter? Tightening strength? Resistance to bending? Also the steel used and heat treatment used vary so there can not be an apples to apples comparison.

The reason I ask is because a few comments back it was said to try & use a face cutter with MT2 would be like wet pasta. So it was just to find out at what point you could use a 50mm face cutter. I think old mart did a R8 conversion on a TS. Would that suffice. Hence the question. The other comments seem to be the quality of the arbor. So made me think would say a Sandvik be so much stronger than a cheap bought item.

Steve.

What is the size of this one? diameter and bore.

Looks like a BAP 300R 50 22 6T going by the size of the plastic insert boxes that takes the APMT1135 inserts.

Thinking rationally about it, the morse taper fits inside the quill, so the limiting factor is the quill rigidity or the length of tool holder outside the quill.

For a one horse motor, I would suggest that power is likely the limiting factor - along with that extension from the quill and quill rigidity. I would expect that an R8 in that same spindle has a very minimal advantage over MT2, if any - other than quicker/easier(?) tool changing - because the milling head components likely have more to do with the machine capability to use larger cutters.

That one is 50mm dia . The other 2 are 63mm. Do not know the internal until they arrive. From comments though it would seem they will be no good on my machine. I would have thought the main question would be what metal you are cutting. Surely facing on aluminium would be possible & on hard steel maybe out of the question. Or am I missing something.

Steve.

Doing some more homework, which I always hated at school. There are a lot of factors to consider to ask if a 50mm facemill could be used in a MT2 arbor. Speed, Material, feed rate. Depth of cut.The actual machine rigidity. Available drive power. Lubrication or dry. Mine is in the very rigid category but not very powerful. So like a lot of folk on here do the math. Which unfortunately I do not have the skills to, my worst subject. I see things but calculus deaf.

A object as say, a piece of Aluminium. 2" square. To be faced off with some form of a milling cutter. The cutter has 1 cutting edge. Work force at that point Vs torque required to cut. 2 cutting edges . Work force at the 2 edges. 6 cutting edges. May be I am dumb but surely 6 cutters Vs 1 equals 6 times less divided into to the driving force would be the same or less than using a fly cutter which is acceptable. Am I missing something. After watching quite a few videos tonight of much lesser machines than mine doing a dam fine job with multipoint face mills makes me wonder what advice I am listening to, theory or actual experience of doing said work. I truly hope it is from experience & not just your idea of what it might be.

Steve.

One tool I would recommend (from experience) which should be fine in MT2 and your available power on the TS is the 25mm - 2 insert end mill from ARC. I use one on my small SX2P (500 watt) R8 mill. Since getting one it is probably my most used cutter, 1604 polished inserts for alu and Tin coated for steels. Available in MT2 at £29.98 and I have found it to be excellent.

As I said earlier with the right inserts in this case aluminium specific ones and a modest depth of cut say 0.5mm to start with I can't see an issue with trying the 50mm head on a MT2 arbor, I'm sure many here would have run MT2 flycutters swinging a 2" diameter at the cutter tip so not much of a difference.

The question of single tooth or six tooth, the six tooth will put more load on the machine if you load each tooth the same as if you took a full width cut off your 2" block at say 0.002" per tooth you could have two or 3 teeth cutting so 0.006 load (not quite that but beyond this discussion) but if you simply run the carbide faster than the common HSS flycutter and feed at the same rate the chip load will come back down so no more load and possibly less than a single point fly cutter. Added bonus is the facemill will be better balanced than a flycutter too.

Just do it... you will soon find out the optimum feed and speed for your face cutter and application. You don't need to have the best of the best, or the biggest of the biggest for hobby work. If in the end it doesn't remove sufficient cubic inches of metal per minute to meet your expectation, then you will need a bigger mill.

If it is of any help I use 43 and 50mm multi tooth face cutters with no problem on a WM16 with MT2 - not a rigid or powerful machine by any standards. Try 0 .5mm on ferrous and 1.0mm DOC on non ferrous say 0.,05 mm chip load at maximum RPM as a start (only 2500 rpm on the W16). I generally prefer these multi tooth jobs to single point fly cutters.

I would have thought that the TS could probably do better than a WM16, being a more substantial machine.

'ang on a minute chaps.

All this stuff about stiffness of the spindle is irrelevant - the power you can get to the cutter is limited by the drive belt. For those not familiar with the TS light vertical head,, it uses a Z section (3/8 wide) vee belt, 500 mm long. With only a slide and clamp tensioner. Modifications could be made, but they'd be fundamental to get a bigger belt and or a screw tensioner in the mix.

FWIW I use a 40 mm diameter shell mill with APTK1604 inserts, depth of cut about 0.5 mm and feed pretty gentle, as you don't want the cutter to stall 'cos it chips. You can use the cutter in either of the two bottom speeds (approx. 200 and 400 revs) - it makes no never mind just so long as the cutter keeps cutting freely.

The amount of metal you can shift is limited by the power at the cutting edge, not the stiffness of the machine.

My cutter arbour is MT2, yes it would be nice if it was stiffer but that ain't the limiting factor.

It's a light vertical!

Rgds Simon

Not dumb at all, but much depends on how the operator uses the tool. A multi-cutters design purpose is to remove metal quickly. To do that it's pushed at high feed-rate into the metal. To get the intended metal removal rate, a fast powerful rigid machine is needed. That's what's industry have. A fly-cutter does the same job more slowly and is suited to small bendy machines.

But there's no law saying tools must be used exactly as their designer intended. Due to the limitations of home workshops, a Model Engineer probably won't be able to drive a multi-cutter to it's full potential. It still cuts at reduced speed and power but it won't remove metal as well as it might. Could be 'good enough'.

Hence the apparent contradictions. A Tool Catalogue will describe the conditions under which industry will get the best out of a cutter; their goal is making items as cheaply as possible, which means carefully balancing metal-removal rate, tool-life, and power-consumption. That generally means carbide cutters making very fast deep cuts with rigid powerful machines.

But an amateur can put the same cutter in his relatively weedy machine and still get reasonable results from it. Or not!

How the tool behaves at a particular time in a particular workshop depends on a multitude of factors that are rarely explained by home users. What machine, how much power, depth of cut, feed-rate, material all left in the fog. We don't know what inserts are fitted to your cutter. So reports of the same tool vary from 'complete rubbish' to 'excellent' because, when used off-specification, performance isn't predictable. It depends. It's more obviously unfruitful to compare the performance of a family hatchback with a Farm Tractor or a Formula 1 Race Car without mentioning how they will be used!

The same issue applies to machine tools. For example, Stevies Tom Senior mill was aimed at the precision end of the market. It features high-rigidity with a smallish motor in order to improve basic accuracy, a good thing. It was never intended to hack metal in the shortest possible time, and, although the machine could be up-motored to do that, may not be an improvement.

To find out how well your cutter works on your machine, it's necessary to try it. Depending on context it may or may not be suitable. If bought to remove metal at high-speed, it will disappoint because a ½HP motor simply isn't powerful enough to drive it. However, run gently within the limitations of slow or small machines, some report they produce a better finish than a fly-cutter.

All this is liable to confuse the beginner! I found the best approach was to read books, ask questions, and then use tools to make things. I found using tools to be absolutely essential, because it's so easy to miss important hints in books and forum answers. Experience + Theory = Understanding.

Fortunately, getting a feel for tools and materials isn't Rocket Science. Pragmatism works too, it just takes longer and may form bad habits. Start points can often be decided by rule of thumb, and then adjusted up or down for best results. For example, I determine RPM by dividing 10000 by the diameter in millimetres. The answer is about right for HSS and Mild-Steel. Double or triple RPM for carbide, and increase or decrease by a factor to suit the metal relative to steel. Then, on the machine, tweak RPM for best results. It soon becomes second nature, and - knowing how ordinary materials behave - makes it much easier to deal with hardened or otherwise awkward metals. And experience revealing what the machine can do makes it much easier to decide on modifications and tooling.

Dave

Regarding stiffness between R8 and Morse tapers, I would expect MT4 to be equivalent to R8. ISO30 and above are stiffer, the general industry standard is BT/ISO 40. The advantage of any dedicated milling spindle is the steeper angle, making removal much easier than Morse tapers.

If that 50mm six insert shell mill does take APMT11 size inserts, then get some of the cheap Chinese inserts intended for aluminium. They are sharp and will lower the cutting forces substantially when used on aluminium, don't forget to use a little WD40 or similar. I would not use a shell mill more than 40mm diameter on steel on a Light Vertical. 

Edited By old mart on 17/03/2020 10:33:48

Edited By old mart on 17/03/2020 12:52:00

That's a really interesting question!

I'm not sure the question is on target in the sense that I don't believe holding strength is the main design criteria. The main purpose of tapers and other holders is quick tool changing. MT tapers grip well, but their simple drawbar arrangement slows down tool-changes and - incorrectly adjusted - they're prone to slip. Hence other designs that either improve speed and/or reliable setting up.

I'd guess the main limitation of a machine would be it's spindle strength rather than the taper type, and the spindle should be designed to take at least the power of the motor plus a safety factor. So in the case of MT, motor power determines spindle size, and spindle size determines the taper.

I've got books explaining the maximum power that can be transferred by a shaft, but I don't think I've seen anything giving the power handling capacity of a friction grip taper. Machinery's Handbook let me down, I shall do some more digging.

Given that tightening a stone-cold male taper into a hot socket can require a big hammer and heat to release it, I'd guess the power handling capacity of tapers is high - better than a single key, not as good as splines.

Dave

Thanks guys I knew I would get an answer I can understand. I will await the arrival of the cutters & then find out the size of holder I need. It could be a few weeks I guess before I can try them. I have ordered some EN1A mild for a job to do. I need to order some Aluminium for the 1st try. All tips greatly appreciated & thanks again.

Steve.