Machining aluminium

[Alpha1]

What a cracking day Iv got HSS cutting tools of all shapes and sizes falling out of my pockets. I want a bigger lathe I want the Hardinge they have got in the work shop. razz I learnt a lot to day it was great. I made test pieces nothing fancy I knurled, shaped took finishing cuts it was fun. I got a couple of pieces of round bar stock out of the scrap bin they are 316 stainless I'm going to have a go with them to morrow I'm guessing it will be a bit different to working with Aluminium. They lent me some books to read out of the small Library they have. A bit over my head but Ill have skeg at them. I did not get on the Mill it was set up for a job I watched for a bit they were using a dividing head and some other gizmos it was all to complicated for me. I'm hoping they don't have any thing for him to do for the rest of the week but I don't think its very likely. All good fun though.
Milling machines are a minefield as are lathes I'm going to take my time on choosing this one. If I was doing it again I would not buy the lathe Iv got now its to small and its not rigid enough. Id like to up grade but her indoors will kill me.

[Demonic69]

Sounds like a great day. I need to start grinding my own HSS cutters too I think

[ovenpaa]

Knurling is the work of the devil and I do my utmost to avoid it. Pressure/displacement knurling is the most commonly used on manual machines and it does work however for best results you have got to move to cut knurling however there are pros and cons. A cheap pressure knurling tool will probably cost twenty quid, a cheap cut knurling tool 10x this. The pressure knurling tool tales seconds to set up the cut knurling a lot longer and finally finish, I have spent a lot of time knurling in the past and to this day I still scrap items for no apparent reason, the nine before were perfect yet the final one is ruined. My view is cut knurling gives a more consistent and predictable finish.

Good Stainless is lovely stuff to work with and Titanium is even better.

On the subject of machining aluminium choice of lubricant counts for a lot as well as cutting tools. I use indexable carbide inserts the majority of the time only resorting to more traditional tooling for the really fine internal work where my choice is solid carbide and I hand finish the tools with a series of very fine diamond files. One down side of indexable inserts is a lot of them have coatings which have an affinity for aluminium which means they gum up very easily and a good rule of thumb is if the insert is a gold colour it is probably not going to last very long with aluminium. I am lucky in that the Viking has perfected a method of chemically cleaning the cutters so even the cutters specifically designed for aluminium can be recovered as long as they have no mechanical damage however you can never replace that first cut with something new out of the box.

It took us a quite a long time to find exactly the right inserts for the jobs we do and to then find the best suppliers and we often bring things in from Europe and even Australia as opposed to buying here in the UK. Sad really however it is a sign of the times.

[FredB]

??? I have used a simple pressure knuring tool for the past 30 year and never had a problem---nobody told me it was difficult. Next time, no doubt I will screw up.
Fred

[Demonic69]

I've got a tool... Never made anything that needed knurling though :-(

[ovenpaa]

FredB, I have a few pressure knurling tools and they all give good results however I will still scrap something from time to time hence my dislike for such things especially as the knurling is often the very last stage before polishing so a fair amount of time might will have gone into the job. Cut knurling gives a superb finish however it does take some setting up.

[Alpha1]

I'm not familiar with cut knurling Ill have to look it up.

I normally use carbide inserts for facing off and general machining. Most of them come from Cromwell tools. I also use parting off tools purchased from them they are not cheap but they work so much better than the cheaper alternatives. I have ditched most of the tooling stuff I bought in the early days after taking advice from the guys at work. If I want inserts boring bars etc. I go to them for advice. I can get quite a good finish on aluminium now. The HSS ground tools are for profiling I wanted to learn how to do that it turned out really well. Id post pictures of the test pieces but my camera has died. I'm not a machinist but I have learnt a lot in the last couple of days it was great fun. Unfortunately Iv got machining work that I want the Guy to do for me. Iv been putting it off but to morrow I'm going to have to put him back to work. Bugger.
Oops nearly forgot yes they stressed the need for the right cutting fluid.