Models for grinding HSS Lathe Tools

[mikey]

Aukai is right - it takes time to build hand-eye coordination.

I think the grinder you're using is one reason why you're having difficulty. Do you have a belt sander or bench grinder available to you? If so, they will work much faster and better to create the flat faces you need.

I've tried to convey to folks that we are trying to grind flat faces on our tools. The reason for creating those flats is so that when we get them really flat then its simple to then hone them so that the edges where those flats intersect are razor sharp.

None of this is really difficult (says the guy who has ground hundreds of tools and can do it in his sleep as a result) but it does take some time to learn to do it quickly and well. Stick with it, Jeff. There will come a time when a HSS tool is the right tool for the job and you'll have it when you need it.

 

[devils4ever]

My belt grinder makes roughing the surfaces really quick and easy. However, I'm having issues honing them also. Can I use 600 and 1200 grit belts instead? This would help tremendously!

 

[mikey]

Absolutely.

 

[Janderso]

Well, I just spent an hour regrinding another piece of quality HSS. I didn't make any progress. About the same.
I got the angles wrong.
Back to the drawing board.
Maybe I should find out how to do it first. I hate directions!

 

[Janderso]

My belt grinder makes roughing the surfaces really quick and easy. However, I'm having issues honing them also. Can I use 600 and 1200 grit belts instead? This would help tremendously!

I forgot about my belt grinder!
That will save time.

 

[devils4ever]

I forgot about my belt grinder!
That will save time.

Yes. I'm still finishing up my 2X72 belt grinder build, but this thing eats HSS like it's wood!

I can't believe I waited this long to build one. Another plus is it grinds flat faces not concave surfaces. This makes it easier to measure angles.

 

[Janderso]

I started over, used the belt grinder, 600 grit diamond plate, 1,000 then 1,500.
Made a cut, same results. It cuts the Finish is smooth to the touch but it’s not the mirror I get with carbide.
These pics are after I made a .020” cut. .008” per rev at 460 rpm.
Change the speed? Feed rate?
I go faster with carbide.
The pic where the tool tip looks dull is after a one inch cut.
This is old school, Rex HSS.
I’m done for a while. I have to walk away.

 

[Janderso]

My belt grinder makes roughing the surfaces really quick and easy. However, I'm having issues honing them also. Can I use 600 and 1200 grit belts instead? This would help tremendously!

Have you seen the scotch brite belts?
I haven’t used mine yet but if they‘re anything like the wheels!!

 

[mikey]

I started over, used the belt grinder, 600 grit diamond plate, 1,000 then 1,500.
Made a cut, same results. It cuts the Finish is smooth to the touch but it’s not the mirror I get with carbide.
These pics are after I made a .020” cut. .008” per rev at 460 rpm.
Change the speed? Feed rate?
I go faster with carbide.
The pic where the tool tip looks dull is after a one inch cut.
This is old school, Rex HSS.
I’m done for a while. I have to walk away.

Jeff, your tool has good relief angles and decent side rake but zero back rake. See how the edge is horizontal in pic 5 above?

Have you ever seen the model tools we have been sending out? If not, PM @Z2V and have him send you a set so you can see what the tools look like. Take a break until you get them, maybe?

A properly ground HSS tool will more than keep up with a carbide tool. In fact, my tools will take a deeper roughing cut than my carbide tools will and will easily take a micro-cut that no insert will take. Try dialing in a 0.0001" deep cut with an insert and see what happens to your accuracy.

I know it isn't easy to grind tools in the beginning but it gets better, much better, if you stay the course and learn the skill.

 

[Watchwatch]

My belt grinder makes roughing the surfaces really quick and easy. However, I'm having issues honing them also. Can I use 600 and 1200 grit belts instead? This would help tremendously!

Here is my noob experience with the finer belts on my 2x72.

They suck with the softer HSS steels. The joint will quickly create a facet. Finish with a 120g ceramic belt at full speed and use a bench stone for honing with normal HSS.

I ground a Rex95 bit last week and had good luck using a finer belts. I noticed the finish was bad with the ceramic belts. I stepped up to a 220 grit belt, hit the bit on a bench stone to shine it up, checked for facets, and repeated the process as I stepped up grits.


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