HSS tool grinding

[gr8life]

Ok I got my HF tool grinder set up and got a new dressed ao wheel and spent the day grinding tools. Put a 2 ft. piece of 6061 on my Grizzly G4003G 12 inch lathe and made some tools. I experimented with positive & neg. rake, changed the clearance angles, speeds and feeds, depth of cut all to attempt to make a cutter to hog out aluminum. I think I know less now than when I started. So my questions are for hogging alum.

Positive or negative top rake?
End relief larger or smaller?
Side relief larger or smaller?
Round the nose or leave sharp?
Any sites I should look at? Did a search and most sites talk about how to grind a tool but not the job the tool in intended to be used for.
Thanks for any help
ed

 

[gbritnell]

For aluminum I use quite a bit of positive top rake. Side and front rake about 5 degrees. The nose radius depends on what type of finish you want. The larger the radius generally gives a smoother finish. The most important thing when cutting aluminum is not to generate too much heat. Aluminum likes to fuse to the tool if your cut is too heavy. One way around that is to use a little lubricant when roughing.
gbritnell

 

[Maryak]

Gr8life,

Attached is a chart for HSS tool bits and various materials.

Hope it helps.

Also if you have a tool holder which allows centre height adjustment using an angled hole don't forget to add the hole angle to the appropriate tool angles. :

Best Regards
Bob

View attachment HSStools.pdf

 

[shred]

How big a cut are you 'hogging' and what results are you seeing?

I can take a 1/8" cut in 1.5" 6061 on my G4003G without trouble using cheapy carbide bits. I've not tried big cuts in Al with HSS yet, but given how poor the geometry on the carbide is I don't expect any trouble.

Here's a copy of the speed chart I use (in inches and RPM units). Obviously the 4003 doesn't have the full range, but I go with what's closest and work from there.

 

[Maryak]

Gr8life,

Here's something I came across today.

Best Regards
Bob