The Need for Speed

**Anorak Bob** · 24th January 2011, 05:50 PM

Earlier today, I posted something in the Hercus Area regarding the high speed option Hercus had available for their nine inch roller bearing lathes. Turned out that I had both of the pulleys required but I had never fitted them. I thought that I would try them out after Old Fella made a comment in the Engineered Fits thread concerning carbide and speed.

Unfortunately, the two speed motor pulley has a 3/4" bore and the motor shaft is 5/8" so I kept the original single speed motor pulley in place and fitted the two speed High Speed pulley to the countershaft. My linked belt was only long enough to fit the highest speed pulley on the countershaft.

I used a M & W speed indicator to check the spindle speed with the spindle pulley engaged to run at it's highest speed, and it was about 1800rpm. The highest speed available with the correct pulleys fitted is 2600rpm. The normal, non high speed geared nine inch Hercus has a top speed of 700 rpm.

I tried a few test cuts on a piece of 4140. With a depth of cut of 0.015" and a fast feed, the steel cut like butter. I was using a Kennametal KC5025 grade insert. It will be interesting to see how other grades perform. I also better start thinking about coolant.

Bob

p.s. I also found out that 4140 swarf cuts through skin like butter.

Dave J · 24th January 2011, 06:23 PM

Carbide loves the higher speeds (unlike HSS) and brings up a real nice finish. I wouldn't worry about coolant, a lot of guys use carbide in the home shop every day without coolant. If you do you will need some perspex covers to stop it flinging everywhere at those higher speeds.

Dave

**Anorak Bob** · 24th January 2011, 06:59 PM

Dave, What grade of carbide do you use?

Without speed, the grades recommended for slow spindle rpm are limited thereby making choice easier.

With speed, the whole carbide grade thing is a bit of a nightmare with so many options. Then you slip geometry into it and it becomes even more bewildering.

Bob.

Dave J · 24th January 2011, 08:07 PM

I have got no idea what I have got down their without looking, as I don't use carbide much at all. I haven't bought any tips and I only have what has come with machinery or packets I have picked up in tooling lots, so it's a mix.
HSS is my main choice unless I have to machine something hard and then the carbide comes out.
I know what you mean about insert choices

A couple of members on here are up on it and could advise you. They have razor sharp inserts out for aluminum now.

Dave

**19brendan81** · 27th January 2011, 02:10 PM

"They have razor sharp inserts out for aluminum now."

I bought some of these, there is a guy out there who has a website (cant remember the link sorry) who says they are also good for steel at light cuts - but be warned find they break very easily when you get too aggressive on steel and both the inserts I broke went through to the centre hole and smashed into a few pieces rendering the whole insert useless. So, I only use them on alloy now.

Thread: The Need for Speed

Thread Tools

Search Thread

The Need for Speed

Similar Threads

Speed cut

variable speed

Which bandsaw is better, single speed or 2 speed?

Speed Control

Speed

Tags for this Thread

Posting Permissions