Chip Control on the lathe

[schor]

Not sure if this is the best place for this or even if there is any interest. I've been following abom79 and oxtoolco on youtube and they recently got into a series of videos on how to take large cuts with hss tooling on the lathe. So I decided to give it a shot on my 1930's-40's little 1/3hp atlas 10" lathe.

I normally use carbide but the hss blew it away for pure hogging. I have 3 videos of the progression from my first grind to my last and I'll tell you I was surprised I could cut cold rolled that much on my little machine.

Here's the first cut.

Chip Control #1

 

[Kevin54]

Nice job on the tool grinding. There is a certain knack to it, but once you find the sweet spot on grinding the HSS toolbit, you won't forget it.

Just today, I was looking through my cabinets for something, and ran across a parts bin that I brought in from out in the shed a couple years ago. So I got it down, and low and behold, it was my parts bin from work with all sorts of HSS toolbit plus boring bars. Like you, I've been using carbide for years. I now have a new selection of tooling to use on my lathe.

If I may make a suggestion......make a video showing the grinding of the tooling so the other ones that have recently picked up a lathe to tinker with will know how to sharpen a toolbit. It may open up a whole new world for some.

BTW.....great job on the videos. Are you using a camera, or something like a GoPro?

 

[schor]

I will one day show my setup for the camera. lol, it's a blackberry q10 clamped into a magnetic indicator holder. Pretty crude but it works.

I did not show my grinding techniques, well... becuase.... I have none. Maybe now I might have some confidence to show how bad someone can do this and get away with it.

I got a tip from Tom at oxtoolco to put a lead angle on the tool and take more back rake (the rake on the top of the tool). It worked and resulted in this.

Here's the second cut. remember this is 1/3hp belt driven by a bad belt to boot. The motor is not stalling the belt is slipping.

Chip Control #2

Nice job on the tool grinding. There is a certain knack to it, but once you find the sweet spot on grinding the HSS toolbit, you won't forget it.

Just today, I was looking through my cabinets for something, and ran across a parts bin that I brought in from out in the shed a couple years ago. So I got it down, and low and behold, it was my parts bin from work with all sorts of HSS toolbit plus boring bars. Like you, I've been using carbide for years. I now have a new selection of tooling to use on my lathe.

If I may make a suggestion......make a video showing the grinding of the tooling so the other ones that have recently picked up a lathe to tinker with will know how to sharpen a toolbit. It may open up a whole new world for some.

BTW.....great job on the videos. Are you using a camera, or something like a GoPro?

 

[schor]

And here's video #3. Taking 0.1 depth of cut or 0.2 off the diameter. This lathe has a 1/3hp motor, belt drive with a fairly worn belt, hand ground hss tool and 266rpm.

I was amazed this little lathe could take that much off cold rolled mild steel.

Chip Control #3

 

[Doug Arthurs]

I have been following Abom and Ox as well

 

[EdT]

I have been moving back to HSS from carbide as well. The main reason is that I get a better finish and I scored about 50 pounds of HSS tools and blanks at an estate sale. Also, I can easily cut any shape I want which is difficult with carbide. I believe the carbide is harder and more wear resistant, but I think it does not have as sharp a cutting edge as you can get with HSS.
As far as belt slipping goes, I have a 9" South Bend that I've had for over 50 years and a SB heavy 10 that I rebuilt last year. The small machine had a leather belt which was getting tired so I replaced it with one of the maroon colored belts with the hook and pin joint. On a 1/2 HP machine it is marginal for transmitting the torque to the spindle. When I rebuilt the Ten, I got the same kind of belt and it was less than marginal and I replaced it with a serpentine belt from an automotive accessory drive cut and spliced in place. WOW!! That approach works really well so I'll probably do the same thing on the small machine. Belt slip keeps things from breaking if they get over loaded but they still need enough torque transmitting capability to get the cutting done. The slip limit can be adjusted with the tensioning mechanism.

 

[schor]

When I rebuilt the Ten, I got the same kind of belt and it was less than marginal and I replaced it with a serpentine belt from an automotive accessory drive cut and spliced in place.

How did you splice the belt?

 

[EdT]

I spliced the belt by creating a 3" long lap joint using a sanding drum on a dremel tool. It goes pretty fast. I used the fabric in the belt as a guide for how deep you've gone and, as I recall, stopped when the cord was about half showing. That is, I tried not to cut through the cord, but also to remove some of it so there could be a cord-to-cord bond at the joint. Basically I cut away the grooves and then cut about 1/2 way through the un-grooved belt backing from the "top" and the "bottom" so that there is a stepped joint. After cutting the joint, I placed the belt on the lathe and tack glued it together with super glue. I use the low viscosity stuff from the hobby store since it can flow into the joint after everything is in position. I used the spindle pulley as the guide for lining everything up so its straight and then tack glued it in place while it sat on the pulley on which I put a LIGHT coating of oil so things wouldn't get stuck. Super glue will bond rubber to metal like nobody's business so I didn't want that to happen. After the tack glueing I saturated the joint with glue and left it alone for a day or so. Been on several months and seems to be working fine. I considered making a tapered, skived joint, but the stepped joint was easier to do and seemed to maintain the integrity of the cords in the belt better. If you get a belt that is a good deal longer than what you need you can cut it to the length you need (think carefully about that step) and then use the scrap piece to do a test run on the joining technique. The finished belt is a bit thicker at the joint (1/32" or so) but that doesn't seem to be an issue. I run the belt with the grooves on the pulley. Hope that helps.

 

[schor]

Thanks Ed. I might give it a try.