Machining aluminium.

[John DurrantParticipant @johndurrant47282]

When I started machining the cylinder for my Potty Mill Engine I couldn't get a good enough finish. I tried cutting dry, with Neatcut, and as I saw suggested here, with copious amounts of WD40. Nothing was good enough.

Then I remembered that back in 1972 when I was working at A.E.I in Larne I had a lot of aluminium parts to turn and the "Gods" upstairs instructed me to clean out the coolant tank and fill it with kerosene. I had no kerosene, but I did have a bottle of diesel that I used to clean the preservative of a new machine.

It works great.

[John DurrantParticipant @johndurrant47282]

[Gas_mantle.Participant @gas_mantle]

Hi John,

I'm making the same engine and what I did was to 'hone' the cylinder with the piston in my drill press using a mixture of toothpaste, brasso and oil – makes a mess but worked well

[MuzzerParticipant @muzzer]

Hi John

I lived in Whitehead near Larne during the early 70s (when my dad was operations manager at ICI Fibres Kilroot) and I used to take the train along the coast to Jordanstown and Belfast High School. That was when ICI made PET (Terylene, Crimplene, Dacron or nowadays just polyester and the stuff we make drinks bottles out of).

The Kilroot factory was closed down along with the rest of ICI over subsequent years. In fact my dad turned the lights off there before we returned to ICI Fibres HQ in Harrogate where he eventually did the same thing then retired. ICI, like GEC is just a memory now….

Seems that AEI became FG Wilson and then part of Caterpilar Caterpilar. Many of the jobs seem to have gone to China although the Larne plant still makes gensets.

Whitehead was an idyllic place to live during my early teens – sailing, fishing, beachcombing, Blackhead, Island Magee etc.

Murray

[mick70Participant @mick70]

I keep some in a jar as well for when im tapping aluminium.

[Clive HartlandParticipant @clivehartland94829]

So, using diesel for tapping when one iof the best tapping/cutting lubes is OSR (Oil seed rape) odd how things come around in a circle when Diesel is about 15% OSR. !

Clive

[Anonymous]

Using the polished inserts designed for aluminium I find that turning dry is no problem, and leaves an excellent finish. Apart from anything else with the surface speeds involved there'd be coolant all over the workshop if I used it. The main issue when turning aluminium is preventing the swarf from 'birdsnesting', getting trapped and then dulling the newly machined surface.

For manual milling I use the odd squirt of WD40, since it is handy in a squeezy bottle, to prevent the swarf from sticking to the tool and/or work. For CNC milling I use flood coolant (Castrol Hysol XF), primarily to wash the swarf away.

Hand tapping is done dry. For machine tapping I use coolant on the repetition lathe or WD40 on the manual mill.

By aluminium of course I assume we mean aluminium alloy. Pure aluminium is horrid stuff to machine; somwhere between fudge and toffee, but doesn't taste as nice.

Andrew

[mick70Participant @mick70]

Posted by Clive Hartland on 03/10/2015 15:27:43:

So, using diesel for tapping when one iof the best tapping/cutting lubes is OSR (Oil seed rape) odd how things come around in a circle when Diesel is about 15% OSR. !

Clive

Got about 40l of red that came from old landy i restored last year.

Had been used off road on farm only.

Wasn't going to waste it.

[Neil LickfoldParticipant @neillickfold44316]

Canola oil is a modified rape seed oil. It works very well for cutting Ali. A bit messy and gummy if you don't clean it up fairly quickly.Neil

[JonParticipant @jon]

A lot will depend on the grade of aluminium, I use the 6082 daily not the best but can leave a finish showing the grain.

Softer gummy grades can be horrendous, virtually nothing works dry or lubed.

[Chris DentonParticipant @chrisdenton53037]

Under what conditions have you had it showing the grain out of interest?

Only time I've had a problem with 6082 was a dodgy piece from ebay that was very very grainy when anodised!

[ChrisHParticipant @chrish]

I am currently using paraffin and spraying it on from a recycled kitchen cleaner spray bottle when I need it on aluminum – seems to give a good finish plus no build up on the tool tip.

[KWILParticipant @kwil]

6082 does not like being anodised because of the magnesium + silicon alloying. You cannot beat HE30 or equivalent for clean anodising. You also get colour changes to the dye colour dependent upon the actual alloy.

[Chris DentonParticipant @chrisdenton53037]

Posted by KWIL on 04/10/2015 16:11:05:

6082 does not like being anodised because of the magnesium + silicon alloying. You cannot beat HE30 or equivalent for clean anodising. You also get colour changes to the dye colour dependent upon the actual alloy.

 

If an anodising company has told you that then they are fobbing you off.

6082 is probably the best anodising aluminium after 6061 & 6063.

These three parts are 6082T6 extruded rod.

 

 

Edited By Chris Denton on 04/10/2015 16:25:47

[Involute CurveParticipant @involutecurve]

They look good, who does your anodising Chris?

[JonParticipant @jon]

Quite agree 6082T6 very good for anodising, that's why I use it and the most common form of aluminium.
21 years but forgot the full UK spec, HE30 is the first part in 6082 ie BS1474:HE30TF

Decent splash anodising there Chris. I usually tone or have the reds and blues etched to avoid the translucency all other colours fine.
Anodisers I have many a run in and a law to themselves when lose or scrap an item because didn't do it right first or second time. Luckily found a fairly local one that cares, good when its three months work down the pan otherwise and no income.

There are loads of reasons you will get colour change even on the same aluminium extrusion, heres just a few.
Surface finish ie grit, spun polish or mop polish finish.
Amount of time left in brightener
Amount of time left in cleaner ie hydrochloric acid
Amount of time left in etching
Amount of time left in the dye
Temperature of the dye
Heat
Actual anodising or even handling of the parts, voltage amperage, sulphuric, who knows if wrong its a cover up and pass the buck, no come backs and seen all the stunts they pull over 23 years in doing and using anodisers.

A good caring anodisers will colour match and get it right first time. Though some will have several attempts then call it a day after scrapping the job. Remember each cock up they have to remove the anodising which removes aluminium and alters the surface finish each time its done. Wondered why several threaded parts together never line up, got piccies how about 270 degrees on a 1mm pitch thread out of true. Who knows how many attempts.

Can mill and turn to see grain structure and rainbow colouring. Have seen a few where grain like pattern shows up after anodising brought about by over polishing!

Last jobs the other week bead blasted 60/120gr then brightened up to look satin all 6082 and T6 tempering and hardness.
**LINK**
Touch too long in brightener **LINK**

[Peter G. ShawParticipant @peterg-shaw75338]

I have a quantity of electrical grade aluminium busbar which I use from time to time. As has been said, this is a very soft, almost pure, form of aluminium and turns horribly when dry. However, paraffin (kerosene) usually produces a reasonable surface.

What appeared to be an even better product, if you can call it that, was when I mixed the dregs of an engine oil can, a hydraulic fluid can, and some mucky (from cleaning something oily or greasy) paraffin together. No idea what proportions, but it worked wonderfully, so maybe there's an opportunity for some experimentation. It's all gone now, so usually I just use mucky paraffin applied with a brush.

Cheers,

Peter G. Shaw

[Chris DentonParticipant @chrisdenton53037]

Posted by Involute Curve on 04/10/2015 17:42:16:

They look good, who does your anodising Chris?

Thanks, I do it myself!

[Chris DentonParticipant @chrisdenton53037]

Posted by Jon on 04/10/2015 18:09:47:

Quite agree 6082T6 very good for anodising, that's why I use it and the most common form of aluminium.
21 years but forgot the full UK spec, HE30 is the first part in 6082 ie BS1474:HE30TF

Decent splash anodising there Chris. I usually tone or have the reds and blues etched to avoid the translucency all other colours fine.
Anodisers I have many a run in and a law to themselves when lose or scrap an item because didn't do it right first or second time. Luckily found a fairly local one that cares, good when its three months work down the pan otherwise and no income.

There are loads of reasons you will get colour change even on the same aluminium extrusion, heres just a few.
Surface finish ie grit, spun polish or mop polish finish.
Amount of time left in brightener
Amount of time left in cleaner ie hydrochloric acid
Amount of time left in etching
Amount of time left in the dye
Temperature of the dye
Heat
Actual anodising or even handling of the parts, voltage amperage, sulphuric, who knows if wrong its a cover up and pass the buck, no come backs and seen all the stunts they pull over 23 years in doing and using anodisers.

A good caring anodisers will colour match and get it right first time. Though some will have several attempts then call it a day after scrapping the job. Remember each cock up they have to remove the anodising which removes aluminium and alters the surface finish each time its done. Wondered why several threaded parts together never line up, got piccies how about 270 degrees on a 1mm pitch thread out of true. Who knows how many attempts.

Can mill and turn to see grain structure and rainbow colouring. Have seen a few where grain like pattern shows up after anodising brought about by over polishing!

Last jobs the other week bead blasted 60/120gr then brightened up to look satin all 6082 and T6 tempering and hardness.
**LINK**
Touch too long in brightener **LINK**

 

 

 

 

I've been anodising for years. I can't really disagree with anything you've written, anodising companies are a nightmare.

I had to outsource once to a company near Manchester and two of the parts came back very pale and patchy compared to another two, they told me it was poor quality material, but all four pieces had come from the same piece of aluminium, the two poor pieces were inbetween the two good pieces in the billet. Also the colour was way to light, apparently I should have specified the anodising depth I wanted rather than just choosing a colour. Ridiculous. 

There are hundreds of variables to go wrong, even anodising temperature difference of 1 degree will cause a difference between batches.

90% of what I do is used bike parts, so it's a different process, much more to do and your working with parts that you don't know the grade of so it's much more difficult! Fairly often you'll do something with identical parts and one of them will be a different grade to the rest. So I do all colours by eyesight now.

As you say getting something too hot when polishing can make it grainy, but I find it will polish better if it is warm before the final polish. Some grades will go cloudy if you polish too fine though.

On your website, who did the black part with the gold mask anodising? It's very good.

 

Edited By Chris Denton on 05/10/2015 00:02:55

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