Southbend toolpost, terrible finish

[goldstar31]

Tool holders with a built-in rake angle are for just that purpose. Saves you having to grind the second angle on the rake surface.

The no-rake holders were for brazed carbide tools.

I wish I had a set of Armstrong holders in 1/4", 5/16" and 3/8". There are some jobs where they are much easier than a QCTP.

Pete

As far as I can deduce, the now defunct Armstrong company created tools which were forerunners of the now much vaunted( by some) tangential tools. The no rake variety for early carbides was simply because carbides were then too]brittle to hold a decent cutting edge- and brute mechanical power was used to literally push metal off rather than cutting it.

Having written this, I am sure that Pete fully understands this.

Adding to his excellent comments, newcomers tend to forget that there have always been problems in producing good finishes and in many industries it was normal to machine to within say 2 or 3 thous of the finished size and then 'paper' or file or transfer the part to a cylindrical grinder.

Few of us have such tooling and subsequent developments have rendered these expedients largely unnecessary. However we as hobby machinists have to resort other solutions. I suspect that there is a lot of unmentioned Grobert files and things like wooden clamps impregnated with assorted grades of abrasives in many workshops.

My excuse( :hDe is the good old fashioned leaded steels such as EN1A which create a beautiful finished surface on quite ancient machines .

I can't recall having seen such comments here before and feel free to accept or reject

Norm

 

[Blogwitch]

10K Pete,

Modern versions are available, I have the 1/2" set, but they are only horizontal ones, a few items down on here, they should be available in the US if we can get them here.

https://www.chronos.ltd.uk/acatalog..._Sets___Loose_HSS_Toolsteel_Toolbits__66.html


John

 

[Naiveambition]

Thanks goldstar31 for the info , u nailed it on the head. I tried again last nite with high speed steel and same result.
I've often had issues with hss, only one small grinder I have will make a decent tip, although they don't last long.

Something I need to work on is sharpening.
I like the idea of having many tools/options as I can so still working on the hss /Latern setup.

This time I blocked up the cutter using hss to level center. Much better but not ideal. Switched to an insert cutter and was much nicer. Even on my little lathe I use inserts mostly. Granted I know I'm not using their full potential, the seem to work for me. On the Southbend I was taking massive cuts and the tips didn't seem to wear.

issues noticed; the Latern post will seat somewhat leaning when tight and maybe cause the wrong orientation of the tool, or move while under cuts.
Here's 303 stainless using the inserts. You can see the difference in finish to the right, that is an unsupported horseshoe. But the left is with support . I can still tweak the shimming to make it better.

 

[Hopper]

If I can remember correctly, I tried a high speed steel , and a carbide bit. Carbide tip was worse.

My toolset came with a bunch of high clearances bits so ima try that. As for the machine, the bed is dated 1929 but the rest of the parts are variously dated up thru the 50s. The bes as a whole still has all frosting marks on it except the high traffic area.
Admittingly I have no experience to relate to except my 7x10 that's nice, quite, and do the job slowly.... Whereas the south bend can be super aggressive, loudish, shakes the table����. The shaking is from the pulley system as it rotates it bounces the tension plate for the motor. I've tried to soften it by weight . And while better, still needs addressed. This setup is not typical unless you mount the countershaft on the wall.

The Latern toolpost does have a rocker shim and I am using the Armstrong tool holders. I think all of them have some degree of rake built in.
The south bend manual is kinda vague on instructions so. Is the rocker the center adjustment or do I also shim on top of the rocker?

Way too much tool overhang in the picture with this post.
Try sliding the HSS tool bit back into the holder by at least 50 per cent. Leave just the ground part sticking out. Then when you mount the tool holder in the lantern post, slide that back as far into the tool post as possible before clamping down. Less overhang = less up and down force on the whole assembly = less movement = better finish.

 

[goldstar31]

Of course Hopper is quite correct but your remark about the existence of some wear on the bed suggests that there could be wear elsewhere . Several writers have more than hinted and whilst you have done quite well. you should address the matter now.
Again, it would be interesting to find out what your plans are to grind and then hone hss tool bits. There are TWO issues here, not one.

Cheers


Norm

 

[goldstar31]

I came across my old book by Ian Bradley in the Model and Allied Publications of Argos Books entitled Shaping Machine and Lathe Tools.

Oddly it was first published when I was 'Boss' of a Technical Library in the Royal Air Force. I wasn't even 19 until half way through the year but there ye go, laughin and scratchin!

Got quite a lot about lantern tool posts as well as quite a lot on a generation before carbides really came in. My father and I had used them before the War and in a few years, I was doing research into production problems and solutions on cutting stuff made from rock wool.

I can hardly believe it but I often sit bored as a mentor and look at the ceilings of a lot of masonic halls etc and realise that the tiles were still up there- because of me!

Bradley- with Dr Norman Fallows wrote extensively as Duplex presumably because bright as they were , they didn't know how to retire at 55 and live a little.

Norm

 

[Naiveambition]

I finally got around to starting a new tool post. . I've started to get the Latern toolpost to work with shims and inserts. The finish is still not nice but semi acceptable.

The new toolpost is basically a way to see where exactly my issue is. If I get a nice finish with the TP then I'll know the problem isn't machine related. If not, I will be saying.
" im not for suurre, but the problem may be that I don't know what the h@ll I'm doin" 😄

One side accepts up to 1/2 inch toolbits and the other side will be 3/8. Here's where I'm at so far.

 

[john_reese]

Looking at the toolpost I would suspect one of two reasons for the rough finish: an uneven feed rate or a built up edge on the tool.

 

[Naiveambition]

What do u mean by build up on the tool?

Finished the toolpost today and am much happier.. I ran the test on some stainless bar, with an insert I use only for heavy metal removal, not so much for fine finishing. Results were much nicer than before. Ido think with carbide or hss it should be even better.

As for the problem, it seems to b tool post related vs the machine being outta whack. Which is a good thing, since I can now work very close to the chuck which I couldn't before. Here's a pic on the machine

One thing I have noticed is that working on the Southbend vs my 7x10 is that it is a MACHINE. Oil everything , check all the tightening check the belt , adjust this , adjust that, now 10 minutes later we are ready for a cut, My 7x10 is just position tool, oil ways , turn on. Even though I'm still happy with the SB since my smallish cuts seem huge to me vs. my small lathe

 

[Billitmotors]

G'day Naiveambition
I have fond memories of South Bend lathes from my apprenticeship days.
Your finish problems could come from a number different areas.
1. always make sure that your tool is dead on centre unless you are boring and then have the tool above centre.
2. Make sure that the compound slide hasn't been wound forward so that it overhangs it's base support.
3. Check your gib strips adjustments and make sure that there is very little to no play in the compound slide and the cross slide. Any play here will translate to poor finish and marks on your machined surface.
4. You should be able to get a much sharper edge with high speed steel, meaning a better finish,compared to carbide tip tools.
Carbide tools need a lot more power to drive them, more speed and a much more solid machine to get a good finish.
Your South Bend lathe should perform much better using properly sharpened HSS tools leave the carbide for roughing out and use HSS for finishing.
When you are machining the diameter on long sections if you can always put a centre drill in and then support the end of the job with a rotating centre.
Looking at the photo of your Armstrong tool holder, the HSS tool bit looks as if the tool bit has been put in 90 degrees out of position or it has been ground to cut towards the right or tailstock .
If you use this tool bit to cut towards the chuck the side rake on the top of the tool will be giving you a negative rake which will result in a poor finish.
With this Armstrong tool holder you shouldn't need to grind the top of the HSS as the tool has already been set up to give a decent backrake. Also make sure that there is enough front clearance to counteract the angle of the tool holder, as well as any induced angle created by the half moon seat in the lantern tool holder if you are going to use it in future.
I like and prefer your new tool post it is much more ridged and you should be able to use HSS as well as carbide tools in it, although you would be better using HSS tools.
HSS tools are not hard to sharpen they are a lot cheaper and you can taylor the shape of your cutting edge to what you want, as well as what works best for your lathe.
You will find that grinding and then honing a small radius on the point of the cutting edge as well as slowing down and using the correct speeds and feeds will give you a much better finish.
Every lathe is different, a speed and feed that works beautifully for one lathe, will give a better or in some cases worse finish on another lathe. You just have to keep experimenting for the best set up until you find the right combination for your lathe.
I hope that this helps
Rob Jenkins.

 

[john_reese]

Billtmotors is right on.

+1 on the tool being rotated.

 

[john_reese]

If you purchase a QCTP the AXA size is about right for the 9" - 10" lathes. For 12" - 13" the BXA is right. All Aloris and Dickson style toolposts have adjustment screws for getting the tool at exactly the right height.
With the QCTP you pretty much sacrifice the ability to get back rake on a HSS tool unless you are willing to do a lot of extra grinding on the bit. One way to get high side and back rake on a tool for the QCTP is to buy or make a tangential tool. These are my first choice for finish cuts, both turning and facing. I can easily make cuts as small as .0002" with that tool. Another tool for fine finishing is a vertical shear tool. It is primarily for turning but I think it would work for facing starting at the OD and working toward the middle.

 

[goldstar31]

Following up the advice from other contributors- and myself, there is an awful lot of bullsh1t written about tool grinding whereas the best advice came from Tubal Cain( the English one) when he said that one cannot better what the finish is on the cutting edge of one's lathe tool.

If you have a mirror finish in which you can see your dirty finger nail reflected or your can cut off the hairs on your forearm, you are getting somewhere. can you get it from using a grit size of 36 g? If your interest is doing sidewalks, fine. If you are doing what really should be the province of turning to plus 0.002 to o.003" and don't have a cylindrical grinder or whatever, you have to think again.

In my scrappy suggestion about what old Bradley wrote, he actually suggested a rough grind, then a finer grind and the extreme edge- finer still. Of course, you have to buy the book or perhaps the book Amateurs Lathe by Sparey- who probably designed the bloody thing that you want to make- and he suggested 'a pinch of diamond dust'

Diamond dust as he described in the days when I was a lad was a lot more difficult than getting a pack of graded little syringes of synthetic stuff or if you are prepared to settle for merely acceptable surface , then one of these sintered metal plates with perhaps 600 grit will suffice.

Over the many years, I can still hand hone enough to get 'barely perceptical grey dust' from a bit of hss or even a bit of a hex key or even a bike spoke! For younger mortals, you can get away with nothing more elaborate than steadying the honing with a nice bit of smooth plywood.

IMO, far too much ballyhoo is written about this and that tool whereas the simple fact if you want a depth of cut of 10thous, you only need a cutting edge of 11thous. The rest of the tool that is not in cut, can be as rough as a badger's backside.

OK, now go and stop writing about your failures and give your wallet spanner an airing. You might even need a supply of BandAids if you finally have razor sharp tools.

Norm

 

[10K Pete]

I'd like to see a pic of your (Naiveambition) part, in the lathe, with the tool presented to the work ready to cut or even cutting. Still pic.

Like Norm (Goldstar1) has said, a good finish is impossible without a sharp tool presented properly.

Tool posts only need to be rigid, it doesn't matter what type it is!

A sharp tool, held short and rigid, is how you get there. I have put 1/2" tool bits, HSS of course, directly in the rocker tool post to get the needed rigidity.

Pete

 

[goldstar31]

I'm having a think and wondering whether you are swopping and fiddling about and confusing the two separate metal removing processes.

Lots of inserts require relatively massive horse power and rigidity to push the metal away whilst I'm a bit old fashioned and want to cut metal rather than shove it off.

My lathes are at best only putting out about a horse power of which lots is going as friction - BEFORE they get to work.

No good trying to serve TWO masters- and don't really know how to serve one

N

 

[Wizard69]

As far as I can deduce, the now defunct Armstrong company created tools which were forerunners of the now much vaunted( by some) tangential tools. T

Norm

Hi Norm;

Just to clarify Armstrong the tool company is still around as part of the Apex group. That brand is apparently only focused on hand tools these days as I don't see any reference to lathe tooling online. Too bad but likely due to declining markets for the older approaches to cutter holding.

 

[goldstar31]

Thank you for the information. I suspect that these came from a generation where metal removal was roughly done on a lathe only to be finished off in seconds on a grinder.

Again, South Bends and Myfords also come from much the same era and have been largely superseded in the real world of industry.
All that seems to be relevant is that it was not economic to produce this type of lathe in the UK or perhaps Western Europe. The companies have 'gone to the wall' and we are left with suppliers who satisfy minority needs. These minority needs are supplied by a workforce who will accept wages and conditions which are no longer acceptable in the Western World.

The rest of my thoughts are political and have no place here.

Norm

 

[RM-MN]

I'm having a think and wondering whether you are swopping and fiddling about and confusing the two separate metal removing processes.

Lots of inserts require relatively massive horse power and rigidity to push the metal away whilst I'm a bit old fashioned and want to cut metal rather than shove it off.

My lathes are at best only putting out about a horse power of which lots is going as friction - BEFORE they get to work.

No good trying to serve TWO masters- and don't really know how to serve one

N

That really isn't quite true. Inserts are made for industry and quick tool rejuvenation. If the edge isn't as sharp as it should be, it can survive and still cut if enough horsepower is applied and the carbide will last longer than tool steel in that application. With tool steel it takes a sharpening to make it cut well again when it dulls and that takes time and expertise. Changing out a carbide insert takes seconds and no real expertise at all. If you get a carbide insert that requires a lot of horsepower to make the cut, a couple minutes with a diamond stone can make that edge sharper and it will cut better.

 

[bazmak]

Carbide inserts will also take a few grinds on a diamond wheel to produce
a good cutting/finishing edge.I can get a mirrorlike finish in the mill with
a homemade flycutter.The tip dressing works well,although many many
years ago i was told that throwaway tips were just that

 

[DJP]

+1 for Bazmak's comments. Indexable carbide inserts can be sharpened for home/hobby use and they do a good job. You lose the ability to rotate or change inserts while retaining the set up but for my use that's not an issue. In the CNC world it would be important.

I look for worn carbide inserts that I can sharpen as they are cost effective (free) usually. Holders are easy to fabricate so I'm a fan of repurposed carbide inserts. They do need to be knife edge sharp as already stated and they work on small lathes even at low rpm spindle speeds.

Just some thoughts for consideration.