Hi Daniel welcome to the forum.

It sounds like you need a fly cutter to cut the top of the material but like Jason says a bit more detail about mill size and type. Aluminium cutts well with a fly cutter with a small amount of paraffin to lubricate as you go brushed or squirted on with a squeeze bottle.

This is my small one with a 12mm shank and 25mm body with a piece of HSS sharpened on a grinder. The small radius on cutting edge works well on aluminium.

David

I have a the same machine but use steel, until recently I stuck with a fly cutter for larger surface widths but now use a 40mm dia face mill. Both are good but the 4 inserts on the face mill allow deeper cuts where required.

As the others have said a flycutter would have been the traditional choice and one that I would have used, with a plain shank one the same size as David's being my usual weapon of choice. These are not expensive and provided you are happy sharpening the tool bit will get many "sharp" edges for the initial outlay.

But lately I'm more likely to reach for an insert shell/face mill particularly on aluminium with suitable inserts. These tend to be more balanced that flycutters as the speed goes up which is what you want for aluminium and if using as 40mm dia 4 insert body you can feed a lot faster for the same given chip load. You can run one of these at full speed of teh SX2P and wind as fast as you can roughing at 1mm deep per pass and finish with that depth or less with half the feed rate.

From personal experience I would say avoid the very cheap facemills as there are issues with them but mid range from a known source with mid range Aluminium specific inserts will work well, this is what I'm currently using.

In both cases a small amount of Paraffin or WD40 will improve finish and stop metal sticking to the cutter

Edited By JasonB on 24/09/2020 08:26:14

This is my 3 Morse taper Fly Cutter. I use a variety of cutters in it, I just swap the bar over. I also use a piece of HSS in it at times. Pictured is the 6mm round carbide insert for Aluminium. It’s actually a turning insert that I managed to get a box full very cheap. It works really well though on aluminium even with the interrupted cut of a fly cutter. You can also rotate the cutter several times to get a fresh cutting edge so cheap to run. I use it on a VMC but I’m sure you could run it on a smaller mill.

I always wear eye protection but this is particularly important when using any type of fly cutter as it throws chips everywhere!

With a reasonable quality facemill the inserts will not be a problem to fit, just screw em in. very cheap ones can have loose fitting pockets.

Provided you are cutting around the right speed size won't make much difference and unless you have a means to sharpen then its more economic t wear and replace a 6mm one than a 12mm one

If you want a shell mill, there are plenty of 40mm ones whick use 4 off APKT 11, or APMT 11 inserts. You will also need an arbor with a 22mm end which fits your spindle. You can use them with 2 or 4 inserts in them, or even 1 if you reduce the speed to allow for the out of balance forces. Inserts for steel and aluminium are freely available. I am not allowed to post a link on this forum.

Just a small correction APKT inserts are size 10 or 16. APMT inserts are size 11 or 16.

The 40mm shell mills from ARC take an arbor with a 16mm spigot, 50mm and 63mm use a 22mm spigot and the 80mm uses a 27mm spigot. Also, from the web site it would appear that all of the ARC shell mills take size 16 inserts i.e. APKT 16 or APMT 16.

As you have a SX2P mill I assume it has an R8 spindle, it was the only option when I bought mine.

Now the bad news, ARC are out of stock of of R8 shell mill arbours in all sizes. When I spoke to them they said it would be around Christmas time before they expected to receive any more. I was on the email notification list for the last batch which came in a couple of months back but delayed a couple of days before trying to order and the 16mm arbors were already sold out. They seem to sell out very quickly.

R8 16mm shell mill arbors are available from other sources but are at least two and a half times dearer than ARC's. R8 shell mill arbors in 22mm and above are much more widely available.

I have been very pleased with my SX2P and try to support ARC as much as possible as I have found they provide acceptable quality at a fair price. (Usual disclaimer, I have no association with ARC whatsoever)

John B