Step pulley speeds (was: What Speed am I in?)

I am not sure if early 80's manufacture is "antique" but I thought this may be the closest forum to post in. I have a early 80's Taiwanease manufactured mill sold by JET. It's similar to a Grizzly or Husky. AS1 8x30 table. Problem is the Spindle pulley has 4 steps on it as does the middle idler swing type pulley. THe motor pully has 3 steps on it. The belt diagram only shows the 2 4 step pulleys so how do I know what gear I am in? See pics.

SufernTlmkr said:

I am not sure if early 80's manufacture is "antique" but I thought this may be the closest forum to post in. I have a early 80's Taiwanease manufactured mill sold by JET. It's similar to a Grizzly or Husky. AS1 8x30 table. Problem is the Spindle pulley has 4 steps on it as does the middle idler swing type pulley. THe motor pully has 3 steps on it. The belt diagram only shows the 2 4 step pulleys so how do I know what gear I am in? See pics.

Click to expand...

Sounds like the factory stuck the wrong graphic on your machine. You can get a very nice laser tachometer for a very low price on eBay and design your own chart using actual spindle RPM readings. Here are pictures of the belt/RPM chart on an Enco three-pulley Taiwan drill press and the Tach I mentioned. If you look closely at my chart, you will see errors, but it should give you a guide to how to make a chart for your mill, using your own speed measurements.

I bought a new Jet lathe in 1980-something and Jet sent a chuck with the wrong spindle thread with it. They were obviously not a top of the line importer and did not exactly know what they were selling.

Larry

Not restricted to Asian stuff either......my Swift made in Halifax in the 50s had all pot metal speed dials ,which fell to pieces ,making speed selection a mystery .....a cheap photo tach solved the problem.

SufernTlmkr said:

Problem is the Spindle pulley has 4 steps on it as does the middle idler swing type pulley. THe motor pully has 3 steps on it. The belt diagram only shows the 2 4 step pulleys so how do I know what gear I am in?

Click to expand...

A tachometer is handy, but you can also work it out fairly easily without one. I am not the greatest at maths, but with a calculator even I find it simple. The same method can be used with chain and sprockets - instead of diameter, substitute the number of teeth on each sprocket.

Please see the attached example.

I have used pulley diameters of 2", 3", 4", 5" as an example. Measure yours and make a similar chart. I would try using vernier calipers to measure the outside diameter of all the pulleys.

Or wrap a tape measure around each step of the pulley (giving you the circumference) and divide that number by 3.14 for the diameter.

The chart shows a motor speed of 1700 rpm as an example, check what speed your motor is.

I appreciate all the replies. The 3 step pulley chart would be nice. But my machine has 4 steps spindle pulley 4 steps idler pulley and 3 steps on the motor. (Not 4) I am thinking either the top pulley cover was replaced with one from a different machine or it has the wrong chart on it as suggested from the factory. I came up with speed from the tachometer method. Thing that sucks is there is nothing around 700 RPM. Jumps from 543 RPM to 1010 RPM. Wondering about finding a different pulley for the motor to go to 4 steps and giving myself better selection. Then making my own chart and removing the old one.

The 3 step pulley chart would be nice

Click to expand...

One from a little Select mill - values probably not the same as you are looking for

SufernTlmkr said:

I appreciate all the replies. The 3 step pulley chart would be nice. But my machine has 4 steps spindle pulley 4 steps idler pulley and 3 steps on the motor. (Not 4) I am thinking either the top pulley cover was replaced with one from a different machine or it has the wrong chart on it as suggested from the factory. I came up with speed from the tachometer method. Thing that sucks is there is nothing around 700 RPM. Jumps from 543 RPM to 1010 RPM. Wondering about finding a different pulley for the motor to go to 4 steps and giving myself better selection. Then making my own chart and removing the old one.

Click to expand...

If you want more speeds, install a three phase motor and VFD. A 1 HP 240 V 3 PH motor can be run with a 120 V 1 PH input VFD that plugs in anywhere.

Larry

A picture is worth a ton here of the pulley setup. If the idler pulley is stepped and the same size as the spindle you may have all the speeds indicated. You need 2 belts. One from the motor to idler and idler to spindle. If the biggest pulley is missing from the motor then you have what you need. Many combinations with an idler in the center. Only three on the motor makes sense.