Your Home Lathe Tooling

[S_J_H]

Now you can tell me about a tool that will take 1/8" depth of cut on a
9 X 20 lathe,  and I will be sure to file that information in an appropriate place.

Well this is a pic of my old 9x20 taking at least a .125" cut in some 6061 using a Glanze ccmt insert tool under power feed. That was the norm for me on that lathe when roughing larger stock. .1" in leaded steel.


Steve

[Bogstandard]

Steve,

I use the same tips as you do on almost all my tipped tooling, and I have to agree with you fully. That wide angle face can really wack the stuff off. When they get worn on the faces, just use the tips in the tooling that uses the shallower angles.

John

[Stan]

I do most of my work with 6061 aluminum and O1 drill rod. Working with a flat belt Logan lathe I use HSS almost exclusively. I find carbide takes too much power which is not readily available with the flat belt drive. When I need a steel flywheel, a friend working at a steel supplier cuts it out of mild steel plate with a plasma cutter. I have to use carbide tools in the heat affected zone to rough it to OD and then go back to HSS for all the rest of the work. The problem when using carbide on this job is that it doesn't like interupted cuts and I don't have enough power to take off enough in the first cuts.

If I was in a production shop I would be using carbide, But I would be using a gear head lathe with lots of horsepower and lots of spindle speed. Any time the flat belt slips on my Logan, it totals a carbide cutter, but does no harm to a HSS cutter. I can take .001 cuts on O1 with HSS that I find impossible with carbide cutters.

BTW: I have an Aloris tool post with motley collection of tool holders, Aloris, import and shop made. I use mostly 3/8" cutters but may go as small as 3/16" threading bits to get right up to a corner.

[Seanol]

I use the grizzly version of the glanze tooling that Bob showed. After I went through all the inserts (they did not last long) I started grinding HSS and haven't looked back. While I love the finish and the ability to remove alot of metal, the HSS lasts longer in my still learning hands. I do have one problem with HSS. How to get the chips to break? On a-1 drill rod I get a very stringy chip.
I also use GTN parting inserts as well as standard t shaped parting blades. I use a little top rake and I have had very few problems. I do have a 13x40 Takang lathe so it is fairly stout.

Sean

[BobWarfield]

Steve, thank you for visually making a point I've had great difficulty conveying.  With no intended disrespect to your 9x20 lathe, your photo immediately dispells some myths that one hears constantly around indexable lathe tooling:

1.  I can't run my machine fast enough to take advantage of it.

2.  My little hobby machine won't do carbide.

3.  I don't have enough horsepower for carbide.

The other two chestnuts I hear often but do not have a problem with in my shop are:

4.  You can't do interrupted cuts with carbide.  Oddly so many people will use brazed carbide on a flycutter which spends it's life interrupted cutting.

5.  You can't get a good surface finish with carbide.

Bog, your tip is excellent, and one I only recently figured out myself (sorry guys, I am slow!).  The diamond CCMT/CCGT shape has 2 narrow points and 2 wide points.  The tooling sets from Glanz and Micro100 have holders that use both.  If you break or chip a point, there are 3 others that are usable in one or the other of your tools.  It just means they last a lot longer than people would think.

Now lest ye think I am purely a carbide bigot, I am playing around with HSS grinding too.  So far, I am not impressed if I have a carbide tool that does the same chore.  However, there are many instances where there is no carbide available.  Wes is doing a form tool for the columns on the team build.  I love form tools and they're an HSS-only gig.  No carbide inserts there!  There are also specialty cutters for which good carbide isn't necessarily available.  For example you can do a better job on a fly cutter or a boring head if you take a little care.  Lastly, for tiny grooves and cutoff, I have an HSS parting blade I like that is smaller than my Aloris part off tool.  No doubt I will someday have an indexable grooving tool, but this little guy is handy for small work and snap ring grooves.

Cheers!

BW

[Powder keg]

Bob, The tool I am making is tool steel not HSS. It is the same stuff they make drill rod out of. It comes fairly soft, then you heat treat it so you can cut with it.

Later, Wes

[Bogstandard]

i mainly use my tipped tooling if i am removing large lumps, for fine precision work i invariably use hss ground up tooling.

i do also relap the worn out carbide tips, using a water cooled lapping grinder, to the very sharp profiles of hss, but only use them on very fine surface work. if you try to remove too much material with them they just chip off almost instantly, but it will make a nice job on materials where hss struggles to keep a keen edge. i suppose you could use a diamomd lap to do the same thing.

as my motto is, use it until it has no further use.

john

[rake60]

as my motto is, use it until it has no further use.

john

I like your motto John.
During WW2 we had a similar motto here. It was:
"Use it up - Wear it out - Make it Do or Do Without"
How well does THAT fit a home hobby machine shop?

Anyway...
We have carbide insert salespeople come into our shop on a regular basis.
Much of the new products lines are made up of insets with extremely aggressive
rake geometry's.  Being I operate a CNC machine, I can click on the Load Meter
screen and see exactly what kind of tool pressure is being generated.
It's amazing to see what's going on there. 
Higher SFM speeds, lower tools pressures and very little heat being transferred to
the work piece.

Those manufactures are not interested in selling a couple little inserts to some home
hobbyist, but I can guarantee that someone how IS will soon be making the small scale
tooling. 

The most recent new carbide that I am personally testing out at work is made by
SECO/Carbaloy.  In looking through the documentation they provided with it, they list
the TCMT 21.51 inserts that I use in my home tools.
Their recommend depth of cut is .020" 

Rick

[S_J_H]

I no longer have the 9x20 and a rebuilt 1960's 9A South Bend is my main lathe now. Carbide is used 90% of the time on it. I use a 7rib serpentine belt flat side against the pulleys to replace the leather belt and it has a Leeson industrial 3/4hp DC motor and variable speed drive. Belt slip is almost impossible with this setup. It'll stall the motor first. Top speed is around 1400rpm. It will take a .125" DOC in 6061 without even breaking a sweat. CCGT inserts from Seco will easily take .001" finishing cuts and produce some beautiful finishes.
For boring I use only solid carbide bars. Under .001" doc is no problem when sneaking up on a bearing bore. I keep them razor sharp with a diamond file.
I only use HSS for form tools and parting/grooving. I personally love using carbide tooling.

Steve

[aermotor8]

i have a 9" south bend lathe and i use carbide tools about 90% of the time and i have no troubles with it.
i have a 1/3 hp ac motor on the lathe and i can take about .200" cuts in aluminum with the feed on the slowest setting.
the only time i use hss is if i'm grinding a form tool.

when i got the lathe i could not get a good smooth finish on my parts no matter what i did.
after a while and allot of bad words i discovered that the main bearings needed tightening. so i took about 3 or 4 tho. worth of shims out of the bearings and all has been good since.
for parting i use hss cutoff tool in a rear tool holder, with this set up i can part off square,hex and round very easily.

chuck

[S_J_H]

Chuck, you might get some interest out of how I line bored my 9A and made my own bronze bearing shells-
http://bbs.homeshopmachinist.net/showthread.php?t=26578

Yes I agree, .2" DOC are well within the limits of this machine. Not to take anything away from my old 9x20 and it even had a 1hp 3ph inverter motor and VFD, But my 9a SB is much more rigid  lathe and the plain bearings produce a much nicer finish than the tapered rollers on the 9x20. In back gear which is a sorely missing feature of all the 9 and 10" import lathes, the SB is a massive step up in cutting power, At least with a modern belt on the flat pulleys. I run my bearing clearance at .0007". I loosen it to .0015" for 1400+ rpms and it will run well with well for extended periods getting only warm.
 Carbides and the old machines work very well.I find the good inserts to be much much better than brazed tip carbides.
 

[BobWarfield]

Chuck and Steve, your two posts make me wonder whether anyone has ever modified a 9x20 or other import to run with bronze bearings instead of cheap tapered rollers.  Sounds like it would be an improvement and not all that hard to do with a line boring setup.  I would think line boring would even have the virtue of (possibly) making the lathe more accurate in spindle to ways alignment if done carefully.

In terms of "warm", I wonder what the limits are for the bronze bearings?  I would hate to give up my 2K rpm upper end!

Best,

BW

[Powder keg]

For 10 years I ran a Giddings & Lewis Horizontal Boring Mill that was made in 1905 and I could usually hold + - .0005" with it. It had this neat tapered Bronze bushing in the head that you could take up the slack in. The whole machine had bronze bushings through out. It is a fun machine to run. But very slow to todays standards. I rarely ran it over 200 rpm.

Wes

[S_J_H]

Chuck and Steve, your two posts make me wonder whether anyone has ever modified a 9x20 or other import to run with bronze bearings instead of cheap tapered rollers.  Sounds like it would be an improvement and not all that hard to do with a line boring setup.

Bob, I am sure it could be done. A few issues might be a serious problem though. The spindle surfaces were never intended to be run in a plain bearing. I know my 9x20 spindle was not even hardened. I figure you are really pushing it at 2000rpm in a plain bearing with no pressure fed lubrication so you might loose some speed if it's your only lathe. 1400rpm on my 9a runs well  though. My little cnc lathe will turn 4000+ and not even get warm , so I am setup for the smaller diameter work. The finish blows compared to the south bend though.
I would run my old 9x20 to 4000rpm.,since it had a vfd 3ph setup.  But it was far from smooth at that speed. I really enjoy the contrast of old vs new tech in my shop. I'm always on the lookout for another older lathe to restore.

Steve
 

[BobWarfield]

I assume the CNC runs in bearings?  Tapered or angular contact?

Do you think that's the reason the finish isn't as good?

Interesting stuff here.  Sorry to pester about these minutiae!   

Best,

BW