Overhaul of a 9" SB model "A"

[steamer]

Hi Tom,

First thing's first,
I need a good plan. I will elaborate

Dave

 

[steamer]

Tom

Even if I don't scrape the bed Tom, I still need to scrape the guiding and gib ways on the cross slide....that will need an angled straight edge 12" long x 60 degree. I think I can use this to spot the saddle V ways for flatness and in conjunction with the unworn sections of the bed to match the angles.

I will need to clock the saddle Vways one to the other with two precision ground rods to confirm parallelism and squareness with the dovetail ways. I think I can use 2 pieces of precision ground Thompson shafting 18" long for this.

I will need to scrape the top of the TS base so that will require a small flat to check bearing. I have that blank roughed already. I'll check the parallelism of the top with the saddle and a dial indicator while mounted on the base.

I will need to check the alignment of the TS and HS tapered sockets so I will need two mandrels, (1) 3Mt and (1) 2MT
I'll order those from RDG tool tonight.

That's what I need to scrape everything BUT the bed.....I'm still doping out how I would do the bed or more specifically, how would I get/make a suitable straight edge...some 30 inches long!....

The gears are spinning.......tell me what I'm doing wrong....PLEASE!....... :

Dave

 

[ttrikalin]

Tom

Even if I don't scrape the bed Tom, I still need to scrape the guiding and gib ways on the cross slide....that will need an angled straight edge 12" long x 60 degree. I think I can use this to spot the saddle V ways for flatness and in conjunction with the unworn sections of the bed to match the angles.

OK, this interests me cause I will soon want to do the same.

1. I would think that the angle straight edge need not be (should not be) 60 degrees but a tad *less*. As far as I understand what Connelly writes, you need it to assert flatness of the female dovetail, not the angle. In fact you may need some small wiggle room to spot.

2. An *angle template*, as per Connelly, should be used to spot/check the angle at 60 degrees. The angle template can be much smaller in length, as it asserts the angle and not the flatness.

3. Connelly says to alternate the two, cycle by cycle.

Now you seem to be combining the angle straight edge and the angle template in a single tool. This may be kosher come to think of it... I dunno... :-\

I will need to clock the saddle Vways one to the other with two precision ground rods to confirm parallelism and squareness with the dovetail ways. I think I can use 2 pieces of precision ground Thompson shafting 18" long for this.

Pardon ma ignorance, monsieur, but what's a Thompson shaft and where can I get it? I want a similar arrangement as you describe...

That's what I need to scrape everything BUT the bed.....I'm still doping out how I would do the bed or more specifically, how would I get/make a suitable straight edge...some 30 inches long!....

OK, I would be tempted to say that since said straight edge will be used only once, you can make it out of aluminum. You can generate 3 of them automagically...
Now what's (not) wrong with my suggestion... :hDe:

The gears are spinning.......tell me what I'm doing wrong....PLEASE!....... :

wrong? What you plan seems in accordance to what I understand from Connelly, so OK, as far as I know (but I dunno too far, so other's should comment. )

take care,
tom in MA

 

[steamer]

Hey Tom,

I can do the straightedge either way.

Thompson shaft is a hardened steel shafting used for ball roller slides in a lot of automation....It' very round.. but only straight within .001-.002" /foot.....It may be a pig in a poke to go that way.

If you read up on Connelly regarding checking the saddle guide ways parallel to each other and square to the cross slide, you'll see the illustration.

As far as a straight edge........I think a 30" should be a minimum.....36" I think would be better
I don't want to use aluminum for this....just cast iron....if I need to at all!

That will require a new plate, and quite a bit of work......but is doable.
The 12 x 18 plate in my shop sits in the middle of my bench...which is a 24+ inch space....so I could mod the bench and fill the footwell with a 18 x 24 plate and not add to the square footage of my shop....which I can't!!!!!!!!

My shop is 11'6" x 18'6".......I've got three lathes, 2 mills , 2 bandsaws, T&C grinder,Drill press, arbor press, stock rack and a 10 foot long bench, and a 4 foot long wall bench.....and a roll around toolbox......and room for 1! :
I'll be glad to get this done so I can make some room in the shop!
Dave

Most importantly I need a plan from A-Z for this...before I get too much farther into this...I'm continuing with the research....

 

[steamer]

Oh and by the way....where to buy a straight edge casting.....try here

http://www.machinerepair.com/Tools.html

Dave

 

[ttrikalin]

Many thanks...

At some point I'd love to see some photos of your shop to we how to organize mine. I know that you have a Logan and a van Norman. Are the third lathe and the second mill sherlines ?
Otherwise how do they fit ???

Take care,
Tom in MA

 

[steamer]

the other lathe is the Waltham

The other mill is Aciera F1. It's in the foreground in the picture below

Add the SB along the garage door and you get the picture....controlled chaos in this photo....at the moment its in shambles!

It fits VERY TIGHTLY! :big:

Dave

 

[steamer]

Got the HS and TS test arbors yesterday! NICE! From RDG tools. Very reasonably priced also

I will need to verify the accuracy of the arbor , but it appears to be within the .0002" as advertized.

If that is true, the HS spindle taper run out is about .0003" /12".......That'll do!

See there's one component on this thing that doesn't need fixing! :big:

Dave

 

[steamer]

And no I haven't made up my mind what to do about the bed yet....really

Does that sound waffly enough :

But I am getting closer.....

Dave

 

[vcutajar]

Hi Dave

I have been following your rebuild of the lathe with interest. Forgive my ignorance, but what are HS and TS test arbors. I am sure it's something obvious, but can't figure it out.

Vince

 

[steamer]

Hi Vince,

Thanks for checking in!

The Headstock (HS) and Tailstock (TS) test arbors are precision ground cylindrical steel rods of approximately 12" in length with a morse taper shank. Overall accuracy of these items is .0002" run out full length. In this case, the HS side is a #3 MT shank and the TS side is a #2 MT shank.

These are used to test alignment of the headstock and tailstock taper axis with respect to eachother and to the ways of the bed. They are outlined in Connelly's book, "Machine Tool Reconditioning"

It is highly recommended to NOT sleeve one of these arbors up to the next Morse taper size because of the reduction in accuracy. Hence the need for two seperate arbors for a SB 9.

Just trying to do it by the numbers and correct.

Dave

 

[vcutajar]

Dave

Thanks for the explanation. The HS and TS got me confused there. I actually have one of those with an MT3 taper which fits the headstock and tailstock as they are both MT3. I think it is also called a parallel test bar.

Vince

 

[steamer]

Was over at PM doing some research on bed scraping....which at the moment looks like it's not going to happen...I'll have it ground.

Dennis Turk, a SB restorer of great note, put forth a tomb on SB scraping that can be found here

http://www.practicalmachinist.com/vb/south-bend-lathes/bed-way-scraping-128383/


Based on that I did a little investigation of my bed....and I got to agree with him!

I'll post some pictures....to show what I mean.

Dave

 

[rkepler]

Was over at PM doing some research on bed scraping....which at the moment looks like it's not going to happen...I'll have it ground.

You understand that he was talking about flaking in oil pockets and not about general scraping for flatness? I agree with his analysis but a well scraped flat is truly flat and won't retain oil (or crud) well.

That said - I wouldn't scrape a whole lathe bed anyway, it's a lot easier to have it ground and then use it as the reference surface when scraping everything that sits on it.

 

[steamer]

Yes rkepler I do!

And that is the road I'm heading down.

I'll scrape the saddle in to 10-15 spot with a fairly small radius blade so the bearing is a little hard and I think that will retain more than enough oil for purpose.

What I still can't show is a picture of the evidence to back up Dennis's claim.....and its all over my bed!

Pesky Droid!


Later today hopefully
Dave

 

[steamer]

OK....Look what happened to the bearing on the unworn areas of the bed

these were marked with a small master that I know is flat.with a heavy layer of marking...What Bearing!

TS end

HS end....looks the same

The flaking was put in so heavy it took out most of the bearing surface.

Dave

 

[steamer]

Here's a picture of the HS test arbor....

Dave

 

[Don1966]

Dave that lathe is sure looking pretty. Do you think you will savage it without to much expense?

Don

 

[steamer]

Hey Don,

Well, from the begining of this journey, I wasn't counting on reconditioning the bed....but it is what it is. It really isn't too bad, I've lived with worse! but its bad enough to annoy me...and I've got plenty of things that annoy me already.....and I've come this far..I'll kick myself if I don't do it! .I might as well recondition the bed and scrape in the saddle and the TS to it. The Saddle and the TS would have to be scraped anyway....might as well start with a fresh bed with good geometry and use it as the master. Its the only thing left!

Then the lathe is for all intents and purposes will be a new SB 9A. I'm REALLY liking that idea......It lasted 60 years on the first build....I bet I could get 40 years out of it and because I'll take care of her properly, I'll have a lot left over for my kids!

Guess Im getting the bed ground for my birthday! :big: ( : ouch!)

Dave

 

[ttrikalin]

Where are you having it ground?
this is intriguing...

take care,
tom in MA