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mytqik
Joined: 26 Jun 2004
Posts: 127
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Glen,
Here are some engineering based answers.
Drill rpm = ( cutting speed (feet/min) x 4 ) / Drill Diametre.
For mild steel, a typical cutting speed = 100 feet/min. Therefore for a 1/4" drill in mild steel =
drill rpm = 100 x 4 / 0.25 = 1600rpm.
Thats my imperial "rule of thumb"
Here is my metric one (its a bit easier, but less accurate)
Drill rpm = 9000 / drill diametre. therefore for the above question:
drill rpm = 9000 / 6.35 = 1417 rpm.
The imperial one is the more technically correct. For harder materials, the cutting speed should be reduced to around 80.
As for a lubricant, this term is not techniacally correct. It should be "coolant" as you do not want to lubricate the drill bit, you want the drill bit to be cooled. This is to ensure it does over heat, which will anneal the drill bit & it will loose all of its mechanical properties & easily become blunt.
A good rule of thumb, is, if your swarf (the metal shavings the drill is cutting) are coming off blue, is it getting too hot & therefore requires a coolant. Therefore you can use any oil available for a coolant. Chainsaw bar oil, motor bike chain oil or even brake fluid. Just be sure to throughly clean the oil from the metal, especially the brake fluid, as it will prevent paint from sticking in the future.
For stainless steel, kerosene is a good choice.
Next for the jigsaw blade, another rule of thumb is that 3 teeth should always be engaged at any one time. IE the thinner the metal, the high TPI (teeth per inch) required.
I would recomend you save your money & buy the best quality Jiwsaw you can. I personally buy Metabo tools, but these are expensive as they are imported from Germany.
(i just paid over $300 for a 5" grinder, compared to $19 I can pay at supercheap. However Metabo have a 3yr trade warranty & guarentee that you can push in the spindle lock while the grinder is going flat chat. Try doing that with a $19 grinder & it will end in tears.)
As for anodising steel. No can do. Anodising is limited to Titanium & Aluminium. Annodising is the process of deliberatly forming a protective oxide layer on a metal. Aluminium forms an oxide layer which seals the aluminium from the atmosphere. Unfortunately steel does not. The oxide layer we call rust doesn't do this & allows the atmosphere to continue to rust the material.
To anodise aluminium, the existing oxide is removed with an acid, then the aluminium is placed in a acidic solution with a die. This die is obviously the same as the final colout required. Then a huge amount of electricity is passed from an inert anode, through the coloured soltioun to the part to be anodise (the cathode). This forces the oxide layer to build up quickly & to take on the colour of the solution.
As a footnote, Jewellers use lemonade when doing this to jewellery.
You can however sand/polish/strip/blast steel down to its natural state & then cover it with a clear coating. Just be aware that if you get a nick/scratch in the clear coating, the parent steel will rust.
Hope this answers your questions.
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Thu Oct 14, 2004 12:09 pm |
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