Freehand grinding of Lathe bits

Has anyone tried freehand grinding of lathe bits (those with inserts and without). The use would be a diamond wheel that cuts on the side. I tried it with simple bits and it seems to work well, but maybe I am missing some finer points of grinding.

i
Reply to
Ignoramus13611
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Generally diamond wheels at high speed and steel do not go together. The steel has an affinity for carbon which is what a diamond wheel is. Still, from hanging out on the Quorn groups and such, I see that people use diamond wheels on HSS.

CBN is the wheel for steel afaikt.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

Reply to
Wes

Wes, I may be very seriously confused and misinformed. What I was thinking about originally was carbide tipped lathe bits (with carbide tips brazed on). When I grind those, the objective is to grind carbide, but some steel gets ground, as well.

i
Reply to
Ignoramus13611

Well ... you don't really want to use a diamond wheel on HSS, just on carbide.

And for bits with indexable (replaceable instead of brazed) inserts, *I* would not re-grind them, as that would lose one of the important features of the inserts -- the ability to rotate to a new corner or to install a fresh insert once all the corners are used up, and not have the dial settings shift. If you only do one-offs, and

*never* need to replace an insert in the middle of that project, I guess that it does not matter -- but for me, it does matter.

Just that you changed the zero point for those inserts. If you aren't depending on the indexable feature, fine -- but you might as well be using brazed inserts then.

Enjoy, DoN.

Reply to
DoN. Nichols

I've always ground my lathe tools by hand ,neverhad any fancy jigs or such . As far as brazed on carbide tips go ,use a silicon carbide wheel (Green) to sharpen ,it doesnt matter if some steel get ground with this wheel. Ive never bothered to grind inserts ,I suppose you can use old tips to make brazed tipped cutting tools

Reply to
Kevin(Bluey)

You can undercut the carbide (steel support) on a aluminim oxide wheel first.

Wes

Reply to
Wes

"DoN. Nichols" wrote in news: snipped-for-privacy@Katana.d-and-d.com:

Depends on the speed. The whole idea behind Glendo Accu-Finsh grinders is that you can use diamond for everything if you run it slow enough:

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I use mine for HSS just fine. I will typically rough HSS on a regular bench grinder by hand, and then clean them up on the Accu-Finish. I use it all the time on brazed carbide lathe bits.

Doug White

Reply to
Doug White

I'd think it depends on your definition of "freehand". I've ground cutters, but there was always that platform where I could rest the tool; from that point, it was "freehand", as long as that platform was on the correct angle.

There's a diamond wheel in the shop, and the machinists routinely grind carbide bits "freehand", but it's still got that platform- sorry, I don't know the proper technical terminology.

For that matter, how would you do it _not_ "freehand"?

Thanks, Rich

Reply to
Rich Grise

By freehand, I mean no platform whatsoever.

Some grinder have adjustable platforms that adjust exactly to the right supporting position.

Reply to
Ignoramus27305

snip---

Still, from hanging out on the

Only those with little in the way of brains. As you alluded, diamond is absorbed into steel at grinding temperatures unless the surface speed is VERY low. The change in grinding ability of a diamond wheel that is so abused is readily noticeable--assuming you understand the difference.

Harold

Reply to
Harold and Susan Vordos

It's up to you to see that it doesn't. Use an aluminum oxide wheel to grind away the steel that will get ground. Unless you use the tools for extremely heavy cuts (unlikely), it's easiest to grind the steel at a greater relief angle, so even if you touch steel when grinding the carbide, very little is exposed to the diamond wheel. Do not seriously undercut the carbide, otherwise you risk tool failure.

Do not grind steel with a diamond wheel that runs at high speed, regardless of what foolish people tell you. Norton did extensive testing back in the

50's in regards to diamond and steel. They do not go together. If they did, all grinding manuals would suggest they be ground together with diamond.

Harold

Reply to
Harold and Susan Vordos

Ah! But it does! Just like diamond is dissolved in steel, so, too, is silicon. Silicon carbide wheels are NEVER intended for use on steel. The big difference with the green wheels is they are bonded so softly that they slough away too fast for you to recognize that they are dull. No harm to the steel, just a waste of the wheel.

You should move to a diamond wheel, one that runs wet. Today's diamond wheels are but a tiny fraction of the cost of diamond wheels early on. A wheel that cost more than $600 in the 50's now costs under $100. Considering the loss of buying power of the American dollar, they cost about 5% of what they used to. A single diamond wheel, roughly a 220 grit, will see you through your entire lifetime, unless you use it for commercial applications, and will prolong the life of your cutting tools. In the end, a diamond wheel is so cheap to use that a silicon wheel makes no sense, especially when you consider the miserable surface finish they yield on carbide.

Think diamond. You won't regret the decision. Be sure to run it wet.

Harold

Reply to
Harold and Susan Vordos

Not a great idea with carbide and diamond. The relief angles for carbide are shallower than those for HSS, and are easily rounded if you don't have a very steady hand. I do recommend a table for carbide, and I also recommend you NEVER grind dry. Drip isn't very good, either, for you risk fracturing the carbide by thermal shock. And----do not grind steel with your diamond wheel. I can't stress that enough.

I grind HSS without a rest of any description, and with excellent results, and have since 1966. I had been in the trade 8-1/2 years when I was introduced to free-hand grinding. Hated it at first, but once I mastered the technique, there's no way I'd turn back. No way I'd use a rest. They get in the way when you're trying to grind chip breakers or other complex configurations.

Harold

Reply to
Harold and Susan Vordos

Glendo runs their diamond wheel slow, 300 rpm I think, and I've used it on HSS for a touchup with no ill effects. Do you think that the slow speed is OK?

Reply to
Mike Henry

From what I remember of reading Norton's publication on the subject: Yes, there is a noticeable degradation of the diamond, but only in terms of production rates. What I mean is that if you have a wheel that will last 10,000 hours grinding carbide, and it only lasts 1,000 hours grinding steel, that's not about to be a problem for a hobby (or even small production) user.

I don't think I'd sweat it.

Reply to
rangerssuck

=A0The steel has an

nging out on the

Iggy, "confused and misinformed" should be a natural state for an ignoramus :-)

a) I doubt, from reading Norton's literature, that you're going to "use up" a diamond wheel in your lifetime by grinding steel on it.

b) You can get a pretty serviceable tool bit grinder at Harbor Freight for about $160, which would be way more precise than doing it by hand.

Reply to
rangerssuck

If you use a diamond wheel on steel, you will rapidly loose the sharp edges that do the cutting. So do whatever you like, but you are not going to convince me to use a diamond wheel on steel when there are cheaper wheels that work better on steel.

The Harbor Freight grinder may be more precise, but most of the grinding instructions I have seen have wide tolerances for things as rake. And a plain bench grinder can be used to grind concave and convex form tools as well as sharpen drill bits.

Dan

Reply to
dcaster

Yes, you will lose diamond, but define "rapidly." If I was running a cutter sharpening service, I might be concerned. For the few dozen tools a year that I will grind, I doubt it's much of an issue.

=A0 =A0 =A0 =A0 =A0Dan

Well, of course. I was really trying to suggest that it's easier to get the angles you want by setting them up on the machine table than it is to estimate, cut and measure. There's certainly no reason why you couldn't do just as well by hand. Especially for those of us who don't do this every day (or even every week).

Reply to
rangerssuck

Yes, you will lose diamond, but define "rapidly." If I was running a cutter sharpening service, I might be concerned. For the few dozen tools a year that I will grind, I doubt it's much of an issue.

Well, of course. I was really trying to suggest that it's easier to get the angles you want by setting them up on the machine table than it is to estimate, cut and measure. There's certainly no reason why you couldn't do just as well by hand. Especially for those of us who don't do this every day (or even every week).

True. When I was growing up, all the bits were freehand ground. Drills included. Now, with poorer eyesite, I really like my Drill Doctor for the smaller drill bits. Would be nice to have a machine to grind the lathe bits perfectly, but since I have one small lathe and do not have to grind the bits that often, I will hand grind. And on the Carborundum wheel as I only have diamond on the Drill Doctor.

Reply to
Calif Bill

What is the diameter of the wheel? RPM alone does not suffice. You need the SFPM (Surface Feet Per Minute) to judge speeds.

Enjoy, DoN.

Reply to
DoN. Nichols

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