# South Bend Milling Machine - squaring the head



## jakes_66 (Oct 8, 2017)

I've enjoyed setting up the South Bend VMM I bought a few weeks back.  I've been doing a pretty thorough examination of the machine and noticed something that has me worried.  The head is not 'square' to the table.  Some explanation is needed:

The head on this machine does not 'nod' in the same way a Bridgeport machine does.  I mounted my 0.0005" Starrett Last Word indicator in a collet in the spindle and spun it by hand to 'tram' the head to the bed.  I was able to adjust the head left-to-right to my liking, but front-to-back is out by 2.5 thousandths over the 9" width.  I have tried moving the round ram in and out, cleaning and oiling it, cinching the ram pinch-bolts down in various ways, readjusting the knee gib, rotating the collet in the spindle (relative to the indicator), rotating the spindle (relative to the indicator) all with the same results.

How does one compensate for this inaccuracy?  Has anyone been down this road before?

-Jake


----------



## brino (Oct 8, 2017)

Hi @jakes_66 

First, welcome to the group!

Second, if you have not found it there is a manual for that machine here:
http://www.hobby-machinist.com/reso...-operate-a-southbend-vertical-mill-1960.2784/

Third, unfortunately, it looks to me like you have exhausted all the advise in that manual.
Hopefully someone more knowledgeable than me will respond soon!

-brino


----------



## Asm109 (Oct 8, 2017)

Did you snug the lock on the knee travel?


----------



## jakes_66 (Oct 8, 2017)

Asm109 said:


> Did you snug the lock on the knee travel?



Yes I did.  The gib lock seems to be doing its job too.


----------



## Technical Ted (Oct 8, 2017)

Maybe there's some dirt and/or chips or burr in between the two sections that bolt together for head rotation??? Wouldn't take much to throw things off...  If it were me, I would probably disassemble and hone the mating parts with a nice flat stone, clean things up good, put a light coat of oil on them and see if it improves. Same with the ways/gib for vertical on the knee and table. There's probably a booger in the works somewhere! 

Good luck,
Ted


----------



## richl (Oct 9, 2017)

I have the same mill, mine is 1956 vintage. While mine is not spot on, it is a bit better than yours. I looked at mine closely and I do not see an adjustment point, the best I can see is possibly shimming the ways... if that is even possible.

I am wandering if this is an indication of worn ways
Vintage machinery.organization has a better manual, it gives a better parts breakdown.

I plan or rebuilding my machine this winter, and ßome of the suggestions made by Ted will be considered. Keep us posted on what you find and try.

Off topic here, I have not had the chance to ask another owner any questions, I have only read old posts on various forums about this machine. What taper does your spindle have,  mine is a 30 taper. How are you solving holding tooling. I have a taper 30 to er40 collet system. It's a bit of a pain because I have to mill 2 45 degree indents into the hardened spindle for any taper 30 holders I use. Wonderful machine, stiff, enough power, in my case fairly accurate, though the head will move when you are pushing material thru too hard (lots of retramming)
Thanks for any info

Rich


----------



## richl (Oct 9, 2017)

I am curious, does the head and table "squareness" change with the knee position, try setting a dti on the knee and vertical way and move the knee up and down. The same for moving the table in and out on the y axis. You mentioned trying the ram, so I am just thinking what is causing the unalighment.
I don't think the point where the head mounts the ram would be the issue, if there is anything in there as ted suggests, I would think it would move or change when moving the head.
Though loosening the head and spinning it might not be a bad idea. If you have a way to hold the head, overhead crane, engine hoist or chain hoist, might be a good idea to pull the head and check the mating surfaces, if unchanged, the next would be the table and the knee.

After that, I would check for wear in all those areas. I would like to know what you discover, like I said, mine is nearing a rebuild, spindle bearings, and possibly scraping the ways on the knee and table.

I guess this is basically exactly what ted mentioned, sorry, I started to brainstorm how I would do mine...

Hth
Rich


----------



## jakes_66 (Oct 9, 2017)

I do not suspect that the ways are worn, my machine does not appear to have had excessive use during its life.  I did attempt to see if there was some wear in the knee ways by extending the quill as far as it would go, extending the indicator as far as it would go and cranking the knee down maybe 8 to 10 inches.  The squareness issue was exactly the same at 2.5 thousandths over 9 inches.  I think the best plan is to remove the head at the rotation point, clean and stone the surfaces and reassemble.

I was very fortunate to get the original master collet holder with my machine.  It's an NMTB30 taper like yours with the notches for the set screws to retain it.  Keep your eyes peeled for the older Weldon quick change toolholders of the same size, they appear to already have those notches for the set screws.  The collets on mine are a strange type I've not seen before, but I got a full set that is in nice shape.

I just bought the machine a couple weeks ago, so I'm looking forward to giving it a good workout.  It's been all light cuts so far.


----------



## Technical Ted (Oct 9, 2017)

richl said:


> View attachment 243841
> 
> 
> 
> ...



This is a nice picture of that mill. Is that a split in the main body right above the vertical ways??? If so, that's another area where you might have a interference, BUT the GOOD news is that would most probably make a great spot to shim things to resolve your problem!

Ted


----------



## markba633csi (Oct 9, 2017)

Is it possible to turn the upper section of the column 180 degrees? Maybe it's installed backwards? If not then doing some 
work on the rotation point like you mentioned is probably your best bet. 
Mark S.


----------



## richl (Oct 9, 2017)

I had a collet holder with mine, they were called double taper z collets, they are very hard to find now, I used to see new and used ones listed on ebay all the time, not so anymore. The original holder had a lot of runout so I replaced it with the er40 system. You can use any 30 taper holder, but you have to make the indents, and that typically eats at least one carbide mill per holder. I'll keep an eye out for the weldon system, thanks for that tip.

My machine came out of a highschool tech program, so other than the abuse to the table, it appears to be OK. I've had mine for about 5 years.

As far as cuts, it eats even harder metal well enough for me. I try to baby her though, spindle bearings are making noise under heavy cuts and feed. 

OK,  just another question, my motor is a general electric,  frame 180y type kc, 6.5 amp at 230 volts, rated 1 hp by 1956 standards, your head looks a bit different in the picture you have. Mine is more a pancake design. Is yours original?

And thanks a heap for the help, if they is anything you need, or need verification I'll be glad to help

Rich


----------



## richl (Oct 9, 2017)

Something else that may or may not help, I check my tram with a 14" bearing plate I purchased off ebay. Luckily I got 2 of them, one of the was not flat thru out, the other was fine, it took me by surprise to see my table was not in alignment front to back when it had always been before. Make sure you are getting a true reading. 

It can't hurt to move the head and see if the trueness of the head to table changes. They are awkward to pull off and put back on.

As heavy as the table is, I'd rather pull that than the head


----------



## richl (Oct 9, 2017)

This is a nice picture of that mill. Is that a split in the main body right abovethe vertical ways??? If so, that's another area where you might have ainterference, BUT the GOOD news is that would most probably make a great spot to shim things to resolve your problem!

Yes, and it has 2 index pins to allow for easy alignmentioned


----------



## jakes_66 (Oct 10, 2017)

I'm not savvy on the use of those index pins where the column casting meets the overarm casting.  In the parts breakdown they look like they are used for assembly, then after the (4) socket head bolts are tightened they don't serve any other function, correct?

Rich, thanks for the suggestions, but I'm not following you on the purpose of the 14" bearing plate.  Are you just mounting this to the table and taking a reading on that?  I haven't heard of a bearing plate so I'm just not familiar with their use.  Also, I do suspect that the head/motor assembly is original.  I also suspect mine is an earlier or later model than yours, mostly because mine does not have the spindle brake, spindle lock, etc.


----------



## richl (Oct 10, 2017)

Jake, they are probably more correctly called register pins,  correct they are only for alignment during assembly

The bearing plate is just a tool used to aide in tramming the table, instead of dragging a dti or Dia indicator across the slots in the table, I place a true bearing surface down and swing the dti over that. The 14" bearings gives me 7" of swing in all directions. I got 2 of them on ebay a couple years back for 35.00. I am not sure if they are a tool, or a mechnical part used as a tool. I have heard guys here calling them bearing plates, so that's what I call them.

Yea, part of the reason I was asking about the motor was to get an idea of the changes in our machines. My table is 42", yours appears to be the smaller. I did not realize you did not have a brake, I would imagine it would be easy enough to make one though.

I think ted nailed the solution for you though, I'm glad he chimed in, I would not have thought to place the shim at that seam.

I really enjoy my mill, lots of mass, enough power, and it holds true pretty well as long as I don't try to push it too hard. You will enjoy yours too I am sure


----------



## richl (Oct 10, 2017)

Another pieces of information I read about these machines, southbend did not make them, they contracted them out, many were made in England.  

Often wondered how you could tell where your machine was made. Somewhere I found a list of southbend machines and my serial came up as a 1956 vintage machine... though I can't remember exactly where I got the source for that information...

Rich


----------



## Silverbullet (Oct 14, 2017)

From the looks of it , you may have to shim the head where it rotates sideways.


----------



## jakes_66 (Oct 17, 2017)

Update:

I removed the head from the ram last evening and cleaned it thoroughly.  Thankfully there wasn't a lot of debris.  I used a nice flat 4" long Norton medium grit honing stone on the mating surfaces and worked on any (very small) high spots for a good 10 minutes.  I cleaned the surfaces again, oiled them down with Vactra way oil and reassembled.

The result was positive, but still not enough.  The misalignment has been reduced to 2 thousandths over 9 inches, down from 2.5 thousandths before I began.  I think I'll repeat this honing step one more time since my hoisting arrangement for the head is still set up.  I may have been a little conservative in my first effort, not wanting to go too far.  If I can get the reading down to +/- 1 thousandth I'll be satisfied.

Has anyone else ever trammed their head and found this issue?  Rich, how far off is yours?  You said yours is not as bad as mine.

-Jake


----------



## richl (Oct 17, 2017)

I am ashamed to say i dont know exactly, i know the last time i trammed my head, about a month before you started this thread i carefully trammed and found the front to back in the area of about a thousand over 7", maybe a little less. 

Along the same lines, my head will go out easily under heavy cutting, I will be curious to see if you have a similar issue.

Hth
Rich


----------



## richl (Oct 18, 2017)

I'm also paying attention to what you are doing to correct yours Jake,  so please keep posting here as you find things out.

Rich


----------



## jakes_66 (Oct 20, 2017)

Update:

I'm a little disappointed, I must admit.  I removed the head last evening and used the same stoning method that made some progress earlier in the week.  The mating surfaces still show some 'frosting', but there are some suspicious looking sanding marks that I think may be someone else's attempt at squaring the head.  The sand marks are not quite in the right spot, but I can't imagine any other reason someone would have done that.

Anyway, I worked pretty vigorously on both mating surfaces at the head mount with the honing stone, but to no avail.  The same 2 thousandths of deviation remains.  I'm eyeing the ways now, considering that I may have been too dismissive of them before.  Not sure how to go about that... need to build up some courage before diving in to that.

Perhaps I'm too leery of shimming the column-to-ram connection.  It feels like that will de-stabilize the rigidity of the whole machine?  It seems the ability of the machine to absorb noise, vibration and harshness depends on solid connections between pieces?  Sometimes I think I worry too much...


----------



## 4GSR (Oct 20, 2017)

Shimming is not the proper method of gaining the alignment you need here.  It needs to be scraped with a scraper.  A old file will make an decent scraper to get you by using.  There are a few threads dealing with this under "Machine Reconditioning Restoring" I think that right, close enough. The surface shown in your picture needs to be scraped flat to a known flat surface.  I'm not going to go into deep detail on doing this.  Post a thread over in that section if you like and we'll offer advise on getting it squared up for you.


----------



## richl (Oct 20, 2017)

Just curious here, there are 2 surfaces in question here, the head that Jake is showing and the ram mating surface.  Wouldn't any misalignment entail both? Again, just trying to get a handle on how to approach this.

Rich


----------



## markba633csi (Oct 20, 2017)

I believe you're attacking the wrong area if the head to table distance is changing as you swing the head left to right/right to left. 
You need to work on the swivel point on the column to fix that.  Right?
Mark S.


----------



## jakes_66 (Oct 20, 2017)

Mark,

This issue I'm having is that the table is not square to the spindle.  I hope I haven't confused anyone on that.  

The column actually does not swivel on these old SB VMMs.  It looks as though it would swivel (just like a BP), but it is in fact fixed and not meant to swivel.

Ken,

I agree that scraping is needed.  I've never done that before and would need some serious surface plates and practice.  That's a big undertaking for me, but not impossible.  More research is needed, but for me that's half the fun.

-Jake


----------



## whitmore (Oct 20, 2017)

Silverbullet said:


> From the looks of it , you may have to shim the head where it rotates sideways.



This is somewhat puzzling: is the mount flange to be scraped (which is appropriate if
it isn't true vertical), or the head flange being scraped (which means the mount flange is
vertical but the head flange isn't parallel to the spindle axis)?   Isn't the table (the gibs for
vertical and left-right travel) also a possible site for adjustment?

If you rotate the head so it travels horizontally, is its plunge direction reading parallel
to the bed T-slots?  If so, that'd rule out head flange, but not mount flange.


----------



## 4GSR (Oct 20, 2017)

Jake,

When you sweep the table with the dial indicator, which side is high and low.

I tend to agree that the swivel portion of the head is not the coupuite of the problem.  It's generally the knee.  Over time it can wear to the point where the table top will tip outward a few thousandths, showing it to be low on the indicator readings.

This generally turns into a major scraping job to correct.  Ready for a challenge?

Ken


----------



## markba633csi (Oct 20, 2017)

Hi Jake -- Ok I see.  But.. those two pieces of the column separate don't they?  Or not? It looks like they are bolted together
Mark


----------



## richl (Oct 20, 2017)

Jake, your head can not turn left and right? I know there is no nod. Something that was brought up by Ted earlier was placing a shim at the separation point on the column, not the ram/head connection.
Ken is offering the best solution of course, but maybe a 1-2 thousandth shim at the column point will give you some serviceable time if you need the machine right now.

If you do the scraping, a nice walk thru and pics would be nice


----------



## Bob Korves (Oct 20, 2017)

Before doing anything that is a mistake, first understand the geometry and usage of milling machines.  Why is the head being adjusted?  Did it move? Not likely on that machine.  The head and ram rarely get moved, and typically do not wear enough to measure.  Much more likely is wear in the table and in the knee, which get moved all the time.  This leads to table sag from wear, and it may well be different with the table at different distances from the column and at different knee heights.  Shimming, scraping, machining, or other mods to the head or ram to make the head perpendicular to the table is a big mistake.  The angles may be square, but the axes are not, so you will get in a situation where the cutter appears to be moving toward the column as you raise the knee, and the hole you drill by moving the knee will be oval, not round, with the hole location moving as the cut progresses.  The geometry is a parallelogram.

I am not familiar with the details of that specific machine, but you must first start at the machine datum.  That is typically flat vertical portions of the column casting, machined at the factory between the Z axis slides.  These will be surfaces that do not wear, and should be in pristine factory condition. Those are the datum planes of the milling machine, and all the rest of the geometry of the machine is referenced to the datum.   First, make the column knee ways parallel with the datum.  Then, fit the knee to the base slides so that the Y axis slides at the top of the knee is perpendicular (square) to the machine datum, with flat and true surfaces in the proper planes.  Next, same with the saddle to the knee, then with the table to the saddle, then the top of the base column, then the turret with the base, and the _LAST_ thing to do is to make the front face of the ram parallel with the machine datum and the quill parallel to the datum.  Doing it any other way is a short term crutch which will actually make the rest of the machine perform worse.

My strong advice is to use the mill as it is, or to rehab the machine correctly, with no shortcuts.  That takes the services of pros or a LOT of study, learning, and practice...


----------



## jakes_66 (Oct 21, 2017)

4gsr said:


> Jake,
> 
> When you sweep the table with the dial indicator, which side is high and low.



Ken,

When I sweep the indicator across the table, I start by zeroing the indicator on the table surface closest to the operator's standing position.  I check for quill lock, knee gib lock and table gib locks.  I then rotate the spindle by hand 180 degrees  so I'm now showing a reading closest to the column.  In that position the indicator is showing +0.002".


----------



## Bob Korves (Oct 22, 2017)

The .002" sag is honest wear.  It can be repaired, or or it can be compensated for by the operator.


----------



## jakes_66 (Oct 23, 2017)

Well thanks everyone for your input.  I think the best course of action is to use the machine as-is for now with the wear in mind.  I'm just a hobbyist, so it won't be any big deal and it will give me some good practice compensating when machining something critical.  I have used a lathe that was that way.

I will seriously consider scraping the ways and correcting the issue, although that's going to be quite a ways down the road for me.  ('Ways' down the road...  get it?)                       

The investment in time for learning and practice (not to mention expensive equipment) to do the work looks considerable.  I am intrigued in the idea, however, so I'll keep in touch if I decide to tackle this.

Thanks again,

-Jake


----------

