Rubbish Milling Finish in Aluminium

I too was concerned having see the vice jaws, they don't look beefy enough for side loads either. You need an 80mm Kurt clone which I use on my 2A (with the back drip rail cut off.) 

I've bought a job lot of cutters twice now off ebay and have found around 70% are sharp so 'named' Clarkson style cutters are still out there.

Edited By Dave Halford on 29/03/2021 12:10:21

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.

I think some of the problem is in the OP's second post:-

Its a scrap bit of casting which is why it looks manky. Foundry & Fabrication at Totnes have cast the baseplate (aluminium) for my hot air engine and its Flyweheel (ali-bronze). Its the same material as they use for casting gearboxes for cranes and having seen the quality of their finished product this is a very machinable alloy.

This indicates to me the piece in question is probably a runner or riser and as such has not been through the HT process which you would expect given the last highlighted part of the comment above.

Martin

Hi, I checked with the foundry today and the material is LM25 and as you suggest it was a piece of scrap riser.

I found today that a higher feedrate and lubrication with WD40 helped improve the finish immeasurably, I suspect I shall see another improvement when I get the new cutter.

I also tried climb milling, but the machine doesn't seem to feed the work evenly and I didn't detect any improvement in finish.

After all that, I think I've still got some work to do to try different combinations and I'm learning a lot!

Thanks for all the comments - they've really helped.

Avon,

Well with the silicon content in LM25 if heat treated correctly - including the tempering quench in just off boiling water (90C) it should give a good acceptable finish. having said that though the embedded sand in the riser will also not help the finish or the cutter!

As Jason suggested earlier - try a decent piece of known billet, avoid 2018 though.

Martin

As Journeyman said it looks like a dull cutter. In addition it looks like chip welding to the cutter. Cutting lube would prevent chip welding. the metal itself is cast. I suspect it is of unknown composition. The metal itself could be the cause of tearing.

+2 on that. Waste of time trying to machine a bit of old scrag from a riser full of impurities and sand and untempered. Get a good bit of known grade ally, preferably square or rectangular to sit nicely in the vice. Or even a bit of known quality mild steel flat bar etc.