Needing Ideas For Index Pin Block

[mikey553]

Grinding tools on a lathe is not a good idea, but it is up to you of course. Usually a wheel of decent diameter is used so it retains its shape better. End mills are hard and not every abrasive is good for that. Usually a corner of a cup shape wheel is used to grind the relief on the end mill OD. You want to retain this corner for as long as possible. In many cases a diamond or CBN wheel is used so it can last longer and grind cooler.

The end mill to be sharpened should be free to rotate. In many cases air bearings are used to reduce the friction. I am not so sure your lathe spindle bearings qualify for that.

It looks like you are truing to re-invent the wheel out of desperation. I have my doubts you will succeed, but I wish you luck anyway.

[npalen]

Just trying to resharpen a couple endmills for the fun of it. Sharpened the first one and did a couple test cuts and it worked like a new one. I'm not feeling the desperation of which you speak.
I"ve sharpened the OD of endmills many years ago using an air bearing fixture.

[npalen]

For anyone curious about index repeatability, I did a little testing with the setup shown with the indicator about 3" off the chuck centerline. The DTI was showing well within 0.001" consistently with the index pin engaging the 5" chuck backplate. The index holes in the backplate were drilled with a common center drill leaving the 30 degree taper to be mated with the same taper on the locating pin. The brass locating pin also has a straight portion at it's end to match the straight portion of the center drilled holes.

I sharpened a few two and four flute endmill ends using the indexing and a toolpost grinder and am happy with the results. The holes drilled in the backplate were done on a Speedex indexer so their absolute accuracy is based on it.

[npalen]

Added this "gated shifter" to replace the threaded pin for the index. The threaded pin worked great other than a bit slow taking about 15 seconds to do an index. The added piece is made from 1" square aluminum tubing with about three degrees of cam on the vertical slot for locking the pin. The rear slot is a storage position.

Not exactly a "four-on-the-floor" Hurst but it works.

[chipmaker4130]

. . .I've always noticed that the grinder gets very warm when running even when idle and just now noticed the "40 degree C rise" on the nameplate. Am I understanding "temperature rise" correctly in this case? . . .

That spec indicates that the motor can tolerate temp rise up to 40C above ambient. Ultimate temperature therefore depends on existing ambient temp.
There are a few experts here that will no doubt elaborate and clarify.

[npalen]

That spec indicates that the motor temp can tolerate temp rise up to 40C above ambient. Ultimate temperature therefore depends on existing ambient temp.
There are a few experts here that will no doubt elaborate and clarify.

Yeah, I wasn't sure if it meant the max that the motor could tolerate of if it meant to expect that much temp rise above ambient. Guess I would lean toward the latter.

On another note, I've always found centigrade/fahrenheit conversions among the more difficult of doing mental metric/imperial comparisons

[SVS]

😆😆😆
I can think in meters, liters, etc. but if you tell me it’s 50 centigrade out side, best I can do is say it’s halfway between freezing and boiling. I can’t “feel it”.

[npalen]

Putting it all together. The basic ambient temperature rating point of most motors is 40°C. A motor rated for 40°C is suitable for installation where the normal surrounding air temperature does not exceed 40°C (104°F). This is the starting point.

Above taken from this site: https://www.ecmweb.com/content/artic...rature-ratings

[Paul Alciatore]

Finger slots? Care to elaborate?

Nope. Hate it. Finger slots are a bad idea.

-D

[Paul Alciatore]

Temperature conversions between the two scales are actually easy. I do them all the time. All I need are a few simple facts.

1. Water freezing points in centigrade are 0 and 100. The difference is 100.

2. Water freezing points in Fahrenheit are 32 and 212. The difference is 180. And 32 is the difference between freezing point and in deg F and 0.

3. The ratio of 100/180 when both terms are divided by 20, reduces to 5/9. Those two numbers, 5 and 9 are the relative sizes of one degree in each scale. Or put another way, 5 degrees on the centigrade scale exactly equals 9 degrees on the Fahrenheit scale.

4. The two scales must have the same, common zero point before converting the number of degrees from that point. So if you are starting with Fahrenheit, then your first step is to subtract that 32 degrees because the Fahrenheit scale is the one that has the extra 32 degrees. And if you start with Centigrade the last thing you do is to add that 32 degrees.

Those are the facts. And here is how I use them:

Centigrade to Fahrenheit:

1. Divide temperature in deg C by 5.
2. Multiply result by 9.
3. Add 32.

Fahrenheit to Centigrade:

1. Subtract 32.
2. Divide result by 9.
3. Multiply by 5.

That's it. The hardest step in either of them is division by 9.

And if you are only interested in the comparison of a given temperature range in the two systems, then you only need the 5 and 9 for the ratio. The 32 is only needed when a conversion of THE temperature from one to the other is needed. 5 degrees on the centigrade scale always equals 9 degrees on the Fahrenheit scale. To me that is actually easier then the 25.4 mm = 1 inch. That can only be reduced to 12.7 mm = 0.500 inch. Since 127 is a prime number, nothing simpler exists.

Now you may see some formulae that try to "simplify" things by converting those two numbers to a single conversion factor. So 5/9 = 0.555... and 9/5 = 1.8. But, to my mind that only makes it harder to remember. I find it a lot easier to just remember 5 and 9, two nice, whole numbers. And, of course 32.

YMMV.

Yeah, I wasn't sure if it meant the max that the motor could tolerate of if it meant to expect that much temp rise above ambient. Guess I would lean toward the latter.

On another note, I've always found centigrade/fahrenheit conversions among the more difficult of doing mental metric/imperial comparisons

[npalen]

Or this: https://www.unitconverters.net/tempe...fahrenheit.htm