It's been recently brought to my attention that we need a thread to discuss proper cutting/drilling speeds and how to achieve those speeds on the more common machines. Take for instance everyone asking how to slow down a band saw for cutting metal, or a drill press for drilling metal. Discuss.
The Theory of Revolution....(RPMs)
- Thread starter nine4gmc
- Start date
70Chevy
Well-known member
Speeds and feeds depends on other things than just referring to the material as "metal." Aluminum will cut much easier than say, stainless steel. Using quality drills and blades makes a big difference. Many drill presses have step pulleys on the motor and spindle to change the speed. Often there is a chart explaining what speed each combination will attain. You can do a Google search for what RPM to drill a hole in whatever particular material you are drilling. Some band saws have the step pulleys too. TPI and the grade of the sawblade is critical for cutting steel. Also, can be searched on Google.
Hope this is a start to help.
Hope this is a start to help.
http://littlemachineshop.com/reference/cuttingspeeds.php#Milling
Limiting factor on small(er) machines is rigidity which can be somewhat overcome by a reduction in cutting speed. Your average 14" drill press just isn't stout enough or designed to put a 1"+ twist drill bit through a piece of steel.
Limiting factor on small(er) machines is rigidity which can be somewhat overcome by a reduction in cutting speed. Your average 14" drill press just isn't stout enough or designed to put a 1"+ twist drill bit through a piece of steel.
justanengineer
Well-known member
+1. Lack of mass is another that often goes along with rigidity. Many times lighter/less rigid machines will deflect very slightly or not absorb the cutting vibrations properly and you get chattering cutting tools and/or broken tools. On one hand larger machines often have lower top speeds which limits your ability, OTOH smaller machines have less mass/rigidity which can also do so, there's tradeoffs to each extreme.
Not to jump on a soapbox but I'd also urge anyone getting into machine/metalworking to understand the difference between cutting speed and spindle speed. Cutting speed (feet/minute) charts are common and good, spindle speed (RPM) charts are a bad crutch IMHO when you start using different cutting tools. If you can do the basic math (4*CS/diameter) to convert to cutting to spindle speed you can handle any situation. If youre relying on a spindle speed chart based upon HSS drills/mills/etc youre going to be disappointed should you need to use a carbide drill/mill/etc.