The Home Machinist!

I picked up on some new bits. And because Im new to this I cant tell if im not putting the bit at the right angel or if its dull and needs sharpening.im getting lots of chatter sounds like a 18 wheeler putting on the brakes. I have left hand and right hand cutting bits and threading bits. Seems the only ones I can get to cut desent are the ones I believe to be used for threading.

I'm thinking there's more you need to tell us.. size of lathe, type of bit, what angle you are using, photos would be good..

but..

Just reading this I get a picture of someone who bought some import "carbide" bits and is getting bad results on a lathe that really can't deal with carbide.. even good, sharp, carbide, which is not what those cheap import bits are. No disrespect, but this is pretty common here. Maybe I'm wrong, it happened once before.

There are probably hundreds of posts on this very board on how to grind bits. and probably near that many from folks having the same issues as you. "search" is your friend!

Get a copy of "How to run a lathe" , lots of good illustrations of how to grind high speed steel bits. Once you understand that- i.e., you can grind successful cutters-- the answer to your current problems will be obvious. And you probably won't want to use carbide very much at all anymore.

Yes a few of them are chines carbide bits and a few are working fine and I can get some nice curllys with them and yes also the HHS bits do seem to cut more efficintly. The lathe is a craftsman 109 . someone else said that carbide bits don't work well with the craftsman lathe. why don't the carbide bits work with the lathe. I understand about the chines bits but carbide in general.

Carbide exploits the rigidity of a lathe. Angles exploit the defeat of metal. The carriage is a platform with the axis changed by position of the slides. There is pressure, tension and play. I try to position a tool bit to where it won't be defeated by a pressure that will cause it to dig into or pulled into the work.

All I can add is, I have two well respected 9A S.Bends and they just do not
like carbide, although they will do it but nowhere near HSS. Try grinding a
round nose HSS blank and see. Its like this. I still have my first car my
father bought in 1961. A three year old 1958 Mercury TurnPike Cruiser with
a 430cid marauder 360hp. It requires 100 oct. leaded fuel. Call this fuel
HSS. todays junk fuel works in the car, thats (the carbide tool) but not correct.
I just find carbide wants to act more like a parting tool being cranked in, that
lighter machines dont like. My third lathe weighs in around 5 ton it doesnt
care about carbide I can crank in .030 + and doesnt phase it at all.

carbide wants a very rigid machine, and likes high surface speeds. A 109 isn't going to do that. Many of the Chinee carbide tools come delivered not sharp. Carbide is really brittle, so the edge can get damaged easily- you'd need magnification to see this. You need a diamond wheel (best) or a green wheel (kinda OK) to sharpen them.
The 109 was designed to use HSS.
I run a 13" Southbend. I do, for certain tasks, use carbide inserts. When they stop cutting well, time to change the insert. I bought some of those brazed on carbide bits early on, some went in the scrap bin, the rest are in the original packages in the bottom of my cabinet - been there several years. Never had any joy out of them.
I've inherited some US made brazed carbide bits over the years, they work OK till the edge gets damaged. I don't have a way to sharpen them, so when they get damaged, that's it.

For 95% of what I do, HSS works fine. I bought a white aluminum oxide wheel to sharpen them with per suggestions from this board. It does a MUCH better job. If you only have a 6" grinder (like me) they are kind of hard to find, but Rockler woodworking sells them that size.

Thanks for the advice guys I do have plenty HHS bits and will work with them for now on on this lathe. i'll let you guys know how it works out.

Popeye, we are at nearly the same level of knowledge here I think. I have a formula that sort of works for me. Every time I grind a new HSS bit, it takes me about 2-3 hours to get it right.

I have only made a few "important" things but mostly I am just wasting steel at this point. Every project is more of a learning experience and I just operate with the assumption it will take me HOURS longer than it would take someone with a clue.

There is lots of information on the internet that will "guide" you through the process but ultimately it will come down to having an understanding of basics and practically using a microscope to evaluate the finished bit. Even the slightest irregularity that is not visible to the naked eye (at least my 58 year old ones) can make the difference between good or bad cuts.

People here can help, but I have found only practical hands on experience and the acceptance that you will waste many hours in the educational process is the true teacher.

My 2 cents... Good luck.

That will improve with experience.


You're on the right track.

Harold

_________________
Wise people talk because they have something to say. Fools talk because they have to say something.

Curtis, I would never argue with Harold's statement, "That will improve with experience. " but if you are actually spending 2 to 3 hours in front of the grinder to get a tool ground to work for you I would say you need to go back to the basics , read up, understand the recommended angles, use a protractor.
Old tired bugger that I am, if I spent 3hrs. on the grinder I'd hafta go lie down and get nuthin' done 'cause, by the time I got back I'd forget what this nicely ground tool was for!

Well maybe not two hours at the grinder. Maybe a couple coffee breaks between coffee breaks too. Maybe something to munch on occasionally. But it does take a while.

Popeye, For that 109, you're only going to be working with 1/4"and 5/16" bits. That's a good thing when you're starting out grinding bits. It takes a lot less time to mess up a 1/4" bit than it does with a 1/2". If you have a bunch of used bits, just look through them til you find something close to what you need and regrind it to suit your job. I have a drawer full of various sizes that I have picked up at garage sales, auctions, ect. They come in real handy. I don't remember the last time I actually used a new hss blank. Like some of the others, I have a lot of different carbide too, but I rarely use it. For most of the stuff I do the hss tools seem to work better. If I remember to do it, I'll send you a pic of the misc. 109 parts I have. It seems like I have a box with handles and other misc. stuff.

Chuck