Milling: How do I...

Have you done everything possible to make the set up as rigid as possible? I think this maybe the key. Do you get a difference in finish depending on the direction of cut? If so the spindle axis might not be totally perpendicular to the table. Depending on the mill this might be adjustable.

Assuming this is all as good as you can get it, you might have to scrape the last little bit by hand. This not only should allow perfection of the fit but also leave slight recesses to retain an oil film.

One final thought. The finish might not look very good but what does it feel like? It may be better than you think and serve to retain oil anyway?

Good Luck

Bob

Steve. Endmills are for cutting on the side of them, slot drills are for side cutting and sinking into work. You could try a slot drill or a super mill (3 flutes) I would make and use a flycutter you can then grind the tool till you get the finish you like. You could also try a indexable endmill if you have one but only put one tip in that as a large round nose. Hope this helps.

I have seen this stated many times but then why aren't they called sidemills and why do they have cutting relief ground onto the ends? OK I know you can't plunge cut with them as the centres don't cut but why can't you cut on the end up to, say, 1/4 dia.? As a novice in model engineering I'm not disagreeing with you, just curious as to the reasons.

Another thought; taking a facing cut as described is actually cutting on the side (even if only a few thou) not on the end.

Regards, Russell.

Finish it by filing - it is surprising at how accurate you can be, then if necessary you can go down the scraping route.

if you must use such a small cutter for this.....

try using as much of the cutter face as possible, at least 11mm will work fine, but if it were me i would increase the speed to around 900 rpm, also, if you have the use of an airline, use it to contantly blow the chips away from the cutter, this will stop the cutter loosing its edge so quick, as it will take the fine dust away, which acts like a grinding paste to a small cutter, it also cools the cutter sufficiently, a dust mask is a must though. i would definitly not use an oil based coolant

to be honnest i would make up a small fly cutter if i were you, you will get a much better finish

another alternative is to lay a piece of wet and dry face up on a flat surface and take the part down to size using a circular motion, this will keep the part flat and should give you the finish you require.

HTH

Tim

Sometimes its just hard to get a good setup with the machine you are using to achieve a goog finish. Most of the other replys are right about scraping in the final fit. It does leave areas for oil to reside. A better overall machine is also the outcome when scrapped in. If its a small slide it wont take much time to get it good. There are some good articles on scraping on the web. I am a scraper hand and know how to do it but explaining it on here would be a long task. Proper alignment and fit makes the best machines when done properly.

Thanks folks. I went to have a look at some workpieces machined with a flycutter and I can see the dramatic difference in finishes. I can get down to about 90rpm so I could make a fairly large radius cut. I've also got a

2-1/2 inch face mill, so I could try removing all but one of the tips as suggested.

Many thanks

Steve

I don't want to rain on your parade but... The finish left by a flycutter may look much better than that left by a relatively small endmill but it is likely that it is less flat! The reason for this is that any angular error in quill alignment will cause the machined surface not to be flat and the error is directly proportional to the diameter of the cutter. The corollary to this, of course, is that it easier to see and correct errors with larger cutters. I would advise you to go with a reasonable sized endmill (say 1/2"), use a small finishing cut and finish, if necessary by scraping. You may well find that the visually unsatisfactory finish is actually perfectly adequate.

Mark Rand RTFM

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Do you know, I think I'll leave it alone! I should have twigged straight away the quill alignment problem, having just finished the roughing cuts on a cast angle plate with a 12mm end-mill for exactly that reason...

Best regards

Steve