jon

The brief answer IMO is no, don't even try it.

The blade speed will be far too high and for such work rigidity is the clue to success, I doubt very much it would be successful, however you may prove me wrong.

Emgee

If the saw blade was 80mm diameter then for the same cutting force the torque required would be 20 times as much as required for a 4mm diameter end mill. So if the saw blade was 2mm thick it would be like a 2mm depth of cut with a 4 mm end mill. I don't think I would attempt a 2mm depth of cut using a 4mm end mill on steel. To use the same motor you would need to gear it down by a ratio of 20:1 to increase the torque by 20:1
I agree with the other replies that the answer is NO.

Les.

Edited By Les Jones 1 on 05/03/2021 15:49:42

There aren't any shortcuts with metal, unfortunately

You need metalwork equipment to attempt any successful shortcuts with metal

If your bench top Mill is struggling with a 4mm end Mill, something is wrong, you might as well work out what it is, then you can use you milling machine for its intended purpose.

Right, we've all gone and screwed up our faces and leapt down the poor bloke's throat…. I think we now owe it to him to try to help!

Jon –

You say you have a "hobby grade" milling machine….

Well, so do many people on this forum – probably, most us, really; either now or in the past. So that comment does not tell us much, but if you identify it there's a good chance someone has the same or a very similar machine so is familiar with what it can and can't do.

"… that would struggle to cut, say, a 4mm groove in steel".

As written that suggests criticising it on sight, but I'll assume you have tried it, and struggled to make it cut the groove.

If so, is the machine actually so small and light that you were trying to push it beyond its designed limits (given its handbook). There are very small mills ones available that seem to have a good reputation, but are intended for fine-scale model-making, clock-making and similar very small work. They'd probably cut a 4mm groove, but only at very gentle rates. Nothing wrong with these machines, but even big industrial machine-tools have their own limits.

Otherwise…

What sort of cutter were you using – and, daft question I know, was it still sharp?

Were you using appropriate speed, depth of cut and feed-rate? (The last is not easy to achieve on a small machine with a hand-wound table, and really only comes with experience with the machine in question – plus at times a lot of patience when you can take only shallow cuts and the far end of the work-piece seems a very long way away.)

What was the material? Did you buy a known, reasonable-quality free-cutting grade or were you fighting something second-hand that was the same colour as any other "pre-loved" steel (grey or rust) but actually some high-tensile or similarly resistant stuff? We've all done it – well, I certainly have.

Finally, what actually was the struggle? Trying to cut the steel anyway, or trying to obtain a good finish without a hedge of burrs along the edges? The groove ending up over-size?

I think it would be handy to know what material Jon is trying to cut and which type of cut he is thinking of using to rough it out. A sketch maybe.

The way I'm reading it is, the 4mm slot in mild steel was a description of the capability or lack of, of his milling machine.

If the material in question is aluminium for example, there are aluminium blades made for mitre saws, but great care would have to be taken making cuts in solid stock. Personally I wouldn't attempt that.

Bulk material can be removed by chain drilling and/or a hacksaw, or a roughing cutter, or a fly cutter if it's a face. It just takes longer on a small machine like many of us have.

Ed.

Looks like the mill in question is a little Proxxon FF400 so will indeed struggle to do the cut expediently.

Seems the OP also has a Myford so may be worth setting up the part and milling on that.

According to the Proxxon FF 400 User Manual

**LINK**

It can use commercially available milling cutters with a maximum shaft diameter of 12 mm and a tool diameter of max. 40mm can be used. For an optimum working result, it isnecessary to adjust the milling machine and the milling parameters (feed, depth of cut, speed) to the workingconditions and to choose these accordingly.

We can recommend the milling cutters from our accessory range such as the end-milling cutter set (2-5 mm) 24610 or, for larger jobs, the end-milling cutter set(6-10 mm), Item No. 24620

Therefore should be able to do a 4mm cut in mild steel.

Paul.

maybe the endmill is blunt? or possibly the mild steel is not ‘mild’