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He simplified the formula:

For aluminum you divide the number 1200 by the diameter of the rod you are turning. That gives the RPM your piece of rod should turn to make it into a wheel.
 

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Rich Dumas
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There are many types of aluminum and the ones that are intended for bending operations don't like to be machined, the material tends to push rather than cut and it also wants to gum up on the tool. Before you worry about the cutting speed too much make sure you have a machineable grade of aluminum.
 

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As a general rule I run the spindle speed (milling) as fast as the machine will go if machining an aly billet that won't flex and has plenty of meat.

On the lathe the same is true for the smaller pieces you would likely use in slot cars.

Preferably coolant, (but WD40/kerosene will do) is a must, especially for doughy grades that don't machine well.

Speeds and feeds need to be altered if you get chattering due to thin/slender/unsupported sections and there is no text book to tell you, that comes down to experience, feel and knowing your machine. Order of operations is another important consideration on more complex parts.

- Cam
 

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Can your machinist explain in layman's terms how you work out the thread of a given bolt, etc, in order to tell unhelpful people behind the counter (or on the I'net) precisely what you want? Something I NEED to understand, but I am woefully ignorant (my wife made me say that).

The shame... a man who love the Smiths but doesn't know Whitworth from metric.......
 

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Prof I T
Ting Tong
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hi
best cutting fluid / coolant for ally is parafin.
 

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Al Schwartz
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QUOTE (Ade @ 9 Oct 2012, 02:13) <{POST_SNAPBACK}>hi
best cutting fluid / coolant for ally is parafin.

I believe that "paraffin" in the UK is equivalent to kerosene in the US. Here paraffin is a waxy solid - very useful for lubricating screw threads in wood. Kerosene is very similar to diesel fuel which I've used for this purpose.

EM
 

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QUOTE (howmet tx @ 9 Oct 2012, 16:10) <{POST_SNAPBACK}>Can your machinist explain in layman's terms how you work out the thread of a given bolt, etc, in order to tell unhelpful people behind the counter (or on the I'net) precisely what you want? Something I NEED to understand, but I am woefully ignorant (my wife made me say that).

The shame... a man who love the Smiths but doesn't know Whitworth from metric.......

You need a thread pitch gauge, a pair of verniers and a data table or engineers book.
Measure the pitch (or threads per inch) of the thread which will tell you if it is imperial or metric, measure the OD of the bolt and refer to the thread table to tell you what it is.

- Cam
 
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