Learning how to grind HSS

[mikey]

Getting there! Now try taking a finish cut by turning the tip of the tool towards the chuck so that the area just behind the nose radius on the end cutting edge is touching the work piece. You only need a tiny bit of contact and a light depth of cut, then feed slowly towards the chuck. What you're doing here is taking a shearing cut with the end cutting edge. Use some cutting oil, jack up your speed a little and slow the feed, then see what happens to the finish.

 

[Standingbear]

Well I must not have something right still when I turned into the headstock the chatter was bad. It did almost better than my first attempt at knurling lol. I took the bit out honed it again and retried with the same results. Cuts good straight in and turned towards the tail stock. I do have my piece sticking out to far but no chatter turned other way. The bigger piece closer to headstock was straight in and the smaller part turned towards headstock. That was 800 rpms and my finest feed

 

[mikey]

Are you on center?

Is that mild steel? If so, cutting speed is about 100 sfm. Not sure of the diameter but looks to be about 3/4" at the point of cut. If so, rpm should be about 500 rpm. Try slowing it down and increase feed a bit and see what happens.

 

[Weldingrod1]

Has anyone made .stl models of the model tools? Being able to print a set might be useful... do we have drawings for them? I'd be willing to model them up and test print.

Sent from my SM-G892A using Tapatalk

 

[ttabbal]

I think someone posted STLs in the model tool thread.

 

[Standingbear]

Mikey the bit is on center, slowing the RPM and increasing the feed made it look better and no chatter now. I think my grinder wheel is causing a slight convex in the bit. Got to get my sander built lol. Waiting on my wheels, in the mean time I’m going to try and square up my grinding wheels a little.

 

[mikey]

Mikey the bit is on center, slowing the RPM and increasing the feed made it look better and no chatter now. I think my grinder wheel is causing a slight convex in the bit. Got to get my sander built lol. Waiting on my wheels, in the mean time I’m going to try and square up my grinding wheels a little.

Just to be clear, most folks don't use their tools at this angle. I do because that is how I use my lathe tools - I use my edges - but I've been doing it for decades and my tools are ground fairly well. Keep trying and the technique will come.

Skill in lathe work is about learning to respond to the cut. In the case of chatter, the response is to slow your speed and/or increase your feed. If your lathe tool had been in the normal position where the shank was close to perpendicular to the work, the first response would be to turn the tip toward the chuck a few degrees. If that was not enough then you would slow the speed and increase feed.

In time, you will come to see your cutting conditions (speed, feed and depth of cut) as an intricate dance where each is balanced to produce a good cut. My Sherline lathe has infinitely variable speed and feed. For any given depth of cut or lead angle, I can fine tune a cut on the fly. That little lathe has taught me more about machining than any other tool in my shop.

 

[Standingbear]

I touched up my grinder wheel with a diamond tip then reground the HSS and this time it is even better. I think I had a slight convex on the side facing the work. This is by far the best finish so far. I really appreciate the feed back, I gave up on HSS awhile back and now I might be addicted lol. I’m sure you all get tired of us dumb newbies but it is extremely helpful.

 

[Standingbear]

I kicked the speed back up to 1k this time and slowed the feed more just to see and no chatter this time. Finish probably a little better at the 360 but looking way better.

 

[mikey]

I touched up my grinder wheel with a diamond tip then reground the HSS and this time it is even better. I think I had a slight convex on the side facing the work. This is by far the best finish so far. I really appreciate the feed back, I gave up on HSS awhile back and now I might be addicted lol. I’m sure you all get tired of us dumb newbies but it is extremely helpful.

Wait until you get your belt sander built. It will take your tool grinding to another level. The flat faces will be much easier to hone so your tools will be quicker and easier to sharpen and maintain. As a result, they will cut better if you get the geometry right.

All of us, pros and hobby guys alike, start at the same place as you are now. We all understand it takes some time and a few tips to get going so no, we don't get tired of it. One day, a new guy will come along and you'll step up to take his hand ... that's sort of how this works.