Do you know what Aluminium alloy it is? Looks pretty manky on the outside, which may not signify, but it may not be a machinable grade. Also a possible combination problem: blunt cutters, poor material, and no cutting fluid. First thing to try is wetting the cutter and rod with paraffin or WD40 with a brush. I'd also try faster rpm and feed rate.

Also, holding round sticky out rod in a vice like the photo is highly likely to vibrate and move. Try inverting the rod so the vice grips the flat you've already cut: the flat is much less likely to move. (I'd hold a round object in that configuration in a V-Block)

Few of us can sharpen milling cutters, so no shame in replacing them. Buy a new one to compare known good with what you have before assuming they're all past it, but if they belonged to your dad…

Can't answer the Clarkson question, I'm sure someone else will!

Dave

Looks like an odd bit of cast Aluminium so could be just about anything thrown into the mix and if not heat treated can be less than ideal to machine, you could try eliminating the unknown buy practicing on an known alloy such as 6082.

Any metal won't like dull or blunt cutters particularly non ferrous so investing in some new ones if changing alloy does not cure the problem will help. using the now outdated Clarkson which requires threaded cutters will limit your choice these days but HSS 2 flue would be your best bet for aluminium.

This is the sort of finish you can get with reasonably priced import cutters, not the swarf is the full length of the cut not crumbs, unfortunately the ARC ali specific ones don't come with screwed shank.

Also up your speed, 5/8 HSS can be run at about 2000rpm on Ali if the old Centec is upto it.

Edited By JasonB on 28/03/2021 18:41:11

You need threaded ones in the Clarkson otherwise they will pull or wander out, that is why I said your choice will be limited.

I think there are adaptors available or could even be made that would let you hold a "weladon" shank cutter (parallel with a flat for grub screw) of a smaller diameter which will open up the choices of available modern cutters. Hopefully a Clarkson user will show you what they are like.

As already mentioned, that cutter looks blunt. New threaded shank cutters are easy to get hold of, but beware, metric sizes need metric collets and inch sizes need inch collets. Keep the new sharp ones exclusively for non ferrous metals.

Edited By old mart on 28/03/2021 19:43:34

If you have a MT2 fitting spindle, you could get an er25 collet holder which runs up to 16mm shank diameter. That would hold plain shank cutters as well as threaded shank ones. That would allow a much greater range of tooling. Selling the Clarkson would go most, if not all the way to financing an er system.

Hello out there,

One piece of advice missing? When cutting aluminium the cutter should rotate "climb milling" – as shown in the more recent picture, the rotary table should be rotating Anti-clockwise, or as shown – cut completed.

I use, and can thoroughly recommend, the ACCUPRO single-flute solid carbide 'router' cutters for aluminium, sold by MSC Industrial, BUT, they are breathtakingly expensive, and they have plain, metric, shanks. Wickedly sharp, so watch your fingers.

I endorse the comments by Brian Howett 2, re: climb milling, which is essential for the best finish.

Lubricant helps too, but can be neat cutting oil if the stink from WD40 or paraffin is too strong.

The earlier comments about material grade and provenance are spot on.

Run the cutter as fast as you can, and apply a decent feed rate, for a finish as shown by JasonB.

Cannot recommend the use of sharp cutters and some sort of fluid enough. My preference is for paraffin/kero on al alloy. WD40 is ok but leaves a waxy finish in the overspray areas. Fantastic for displacing water though!! Kero is probably cheaper as well.

cheers

Bill

Look at the size of Jason's chips and then at yours. Jason is feeding fast enough to be cutting, I think you are feeding too slowly and probably rubbing as much as you are cutting. Plus the other points regarding sharp tools and fluid to help. Find a speed and feed calculator on line and learn how fast to turn the handwheel for the suggested feeds. For a 3 flute cutter Ø5/8" with rpm at 600 you need to be feeding in at about 3.5" (90mm) per minute as a starting point then adjust feed up or down to suit the actual conditions. For a 2 flute cutter the feed would be 2/3 of that required for a 3 flute cutter, 60mm/minute.

Rubbing produces heat that can cause the aluminium to become tacky and help it stick to the cutter which adds to poor finishes.

Rigidity of workpiece holding is also very important. Looking at your picture the vice has serrated jaws. To me this makes it look like a drilling vice and not a milling vice which usually have smooth jaw faces. if it is not a milling vice that may also contribute to a poor finish.

Martin C

Edited By Martin Connelly on 29/03/2021 08:46:30

Screwed shank cutters are indeed still readily available but as I have said choice is quite limited, you only need to look at something like MSC's catalogue 5 pages out of 60 for screwed and that's before you get to indexable.