Models for grinding HSS Lathe Tools

[finsruskw]

I have a fairly new Sears 6" bench grinder, 1/3 HP.
Is this enough oomph for grinding tool bits?
What type wheels should I use?
The only ones available around here are worthless, you can actually see them wearing away as you grind a bolt or anything else for that matter.
My gut tells me I need a bigger unit w/more HP.

I feel a ;lathe is on my radar scope for sometime this winter/spring.
How many of you guys, if any, are running an Atlas?

 

[mcdanlj]

Is this enough oomph for grinding tool bits?

It's just time. And if you are looking at small lathe and something like the inexpensive 50-pack of 3/8" blanks linked (much) earlier in this thread from ebay seller niuniucme, it's less time than if you are going to be cutting 1/2" blanks... I have cut the square tool in 1/2" HSS on my 1/2 HP bench grinder with 60 grit norton white aluminum oxide wheel, finished on 120 grit and then honed, and it was a bit of an exercise in patience. I'm torn between "what's the rush?" and "it would be a lot of fun to build a 2x72" — so far, "what's the rush" has won.

 

[mikey]

I own a Sears 6" bench grinder and yes, it will grind tools. If you plan to use it to grind HSS lathe tools then I would suggest you consider CBN wheels for it. The wheels are intended to grind HSS and will probably last your lifetime. They do not need dressing, they do not blow up and they will far outlast an abrasive wheel.

 

[finsruskw]

WOW!
They sure are proud of those, huh??!!
But, I guess it's like many things in life, You want to play,.... you have to.......

 

[Dhal22]

Doing tons of reading while I think through lathe options. Time to join this thread I think. Grinder or belt sander? I have both.

 

[finsruskw]

Any reason why I cannot use plain 3/8" x 3/8" bar stock for practice grinds?\
A 5'chunk of it can be had or practically pennies.

 

[tweinke]

Any reason why I cannot use plain 3/8" x 3/8" bar stock for practice grinds?\
A 5'chunk of it can be had or practically pennies.

There is no reason you can't use bar stock, the keystock was suggested because its relatively cheap and grinds easily

 

[WobblyHand]

Been busy. First I cut a notch in the side of my 2x48 grinder. I used a 7" portable grinder, that I could barely control. That thing was heavy and had a lot of gyroscopic movement. It wasn't pretty. But, it's done. Then I made a rest extension so I could support the tool bits when doing the rake.

Then I coarse ground 3 tool bits using 40 grit ceramic. The ceramic grit cuts keystock pretty quickly. Here are the 3 bits from the top, side and end.

On the side view of the knife bit, you can see a 2 stage grind, right about where the mark is. I had to grind in two stages, because I don't have full access on the left side of the belt. By grinding in stages, I was able to create the knife edge.

A special shout out to @ttabbal who sent me a beauty of a bit! Thanks Travis!


To the question section. I have an assortment of ceramic belts. (36 to 120 grit) I used a 40 grit. It's fast, but as you can see, (in my bits) it leaves pretty deep gouges. When do you switch grits? At what stage of the grinding? What is recommended? I can see it's kind of easy to sort of get the first grind ok - but it looks like it's also easy to mess things up in later stages.

 

[mikey]

You're doing great! Your overall tool shapes and angles look really good to me. And yes, Travis is awesome!

I usually use a coarse grit to shape as you did above, then switch to an 80 grit belt to remove the coarse grind marks, then I hone. However, you can step your way up through the grits if you prefer. What you are trying to accomplish when changing belt is to remove the grind marks from the belt before. You will find that going from a 32 grit to 80 grit belt, then switching to a coarse, then fine, then extra-fine diamond stone works well for lathe tools.

The only time I step up through multiple grits is when I need a tool for precision turning. I will shape at 32, smooth at 80, refine at 120 and then quickly step up through the remaining grits until I hit 600 grit. Then I use a fine India stone to remove belt marks, then a flat Translucent Arkansas stone to produce a mirror finish. That tool will take off a tenth in steel.

 

[DavidR8]

Those look great @WobblyHand !

@mikey what type of hone do you recommend?
I have a fine diamond home.


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