Models for grinding HSS Lathe Tools

[shorton]

When using the tool, I'm fuzzy on what the tool angle is supposed to be relative to the workpiece. Not shank/square I gather.

 

[ttabbal]

The radius is tough to do on the belt properly, for me anyway. I found the coarse diamond card works well with a bit of pressure it only takes a few passes. Then just blend it in.

 

[shorton]

Thanks, can you point me to and example of exactly what I need to order?

 

[ttabbal]

When using the tool, I'm fuzzy on what the tool angle is supposed to be relative to the workpiece. Not shank/square I gather.

Start with it perpendicular to the work and ensure that the tip is on center. Angling a bit toward the headstock or tailstock changes how the tool cuts. A few degrees toward the headstock roughs a bit better, toward the tailstock gives better finish. A lot depends on your specific tool, lathe, and workpiece, so it's good to experiment and learn your setup on some scrap when possible.

 

[ttabbal]

Thanks, can you point me to and example of exactly what I need to order?

I use these and have had good results.

https://www.amazon.com/dp/B00006IIO3/ref=cm_sw_r_sms_awdo_t1_vK55Ab4AGC6W4

 

[ACHiPo]

Another complicating factor might be that platen. It attaches only on the bottom so rigidity is compromised; as you apply force into the belt, the platen moves backwards. You might look for ways to stiffen the platen, like welding side plates to it or perhaps a gusset of some kind behind it. Regardless, the platen has to be solid or your grinds will suffer.

The other thing you can do is find a stronger tracking spring to help keep the belt from moving.

I also found that ceramic belts cut much better than aluminum oxide belts. They require less pressure to cut well so you might want to try them.

Finally, try using M2 HSS instead of cobalt. Cobalt isn't hard to grind but it does require more pressure to cut and that might cause your belt to move. A ceramic belt plus M2 steel will give you a better chance at a decent grind.

Mike,
Great input as usual. I am using ceramic belts, and even stepped up to an 80 grit for this task, even though 120 grit is amazingly aggressive.

I think I need to figure out a way to strengthen the arm of the grinder. I'll just get the belt tracking dialed in, then if I put any sideways force on the arm the belt will hop to the side. The spring seems plenty strong.

I suspect you're right about the platen. Until I get a chance to dial in the belt grinder, maybe my best bet is the 8" bench grinder with 36 and 80 grit wheels. I'll also see if I can't find some plain HSS.

 

[Aukai]

I have a 2 x 48 belt grinder. What I did to reinforce the platen was to cut down a piece of box tubing that my platen fit well, then welded them together, and added/epoxied the Pyrex glass to it.

 

[mikey]

Being past time to pass my models on, I forced myself to take time to grind the primary today. With the excellent directions on post #104 I had no trouble. My belt grit may have been a little light as it took a few minutes, especially on that first big cut. But I was able to reproduce the shape, no problem, first try. I tried touching the radius with the belt and think I made it too big. Hard to see 1/32 at my age LOL. A stone in order for that step. I piddled with it taking some huge cuts in 6061 effortlessly. Got a little galling on my tip but I had no lubricant which was probably part of the reason. And no honing. Excited to be able to do this. Thank you.

Photos, models vs mine after playing around and I redid some edges a couple of times to sharpen the radius I made a hair big and ugly.

Looks really good, shorton! You got all the angles right - looks just like the model. It amazes me that you guys can do this right off the bat.

Travis has given you the dope on lead angles using far fewer words than I did in post 107.

I also agree with him re the diamond stones for honing - I use the same ones.

 

[mikey]

Mike,
Great input as usual. I am using ceramic belts, and even stepped up to an 80 grit for this task, even though 120 grit is amazingly aggressive.

I think I need to figure out a way to strengthen the arm of the grinder. I'll just get the belt tracking dialed in, then if I put any sideways force on the arm the belt will hop to the side. The spring seems plenty strong.

I suspect you're right about the platen. Until I get a chance to dial in the belt grinder, maybe my best bet is the 8" bench grinder with 36 and 80 grit wheels. I'll also see if I can't find some plain HSS.

Yeah, if the chassis of the grinder is moving under pressure then you're gonna' have issues. You have to find some way to stiffen things up.

Aukai's platen mod is a really, really good one!

 

[mikey]

I have a 2 x 48 belt grinder. What I did to reinforce the platen was to cut down a piece of box tubing that my platen fit well, then welded them together, and added/epoxied the Pyrex glass to it.

This sucker ain't moving, that's for sure!