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Ways - To grind or not to grind?

porsche_v8

Aluminum
Joined
Aug 14, 2006
Location
Wichita Falls Texas
I have this topic over in the South Bend forum but I need some more diverse opinions.

Original Thread Here

I have my 13 x 60 completely apart and everything rebuilt and painted except the bed / ways and before I put it back together I need to decide about having the ways reground.

There is a place in Dallas that will do it. I just know if I skip the grinding I am going to kick myself after I get it all back together.

Any input?

sbx.jpg



Thanks!

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Damned if you do and damned if you don't, that is the issue. Having worked where they rebuilt lathes and mills I can tell you it will not be easy. If you grind the ways you need to grind the saddle and tailstock base and maybe the headstock V's and use Moglite or something like it to bring everything up to original height. It takes a lot of setup and measuring to get everyting right. The grinder will tell you how much to space everything to get original specs. If you only grind the ways nothing will fit. Personally I would live with it or get a better lathe.
 
I would check how much the whole bed is warped before starting to grind

take off as little as possible and another .002

then use precision level to level out the the lathe when finished, let it sit for a month and level it again

i would do it

even though not neccessary to do precision work

operator skill overcomes most any problem

but it feels good to have nice tools and makes work easier
 
I'd be more worried about your bent leadscrew, judging by your pic ;)

As others have said, it all depends on what sort of work you are doing. I've just disposed of a TOS lathe which had more than twice that amount of wear near the chuck, most of my work is only to the nearest couple of thou so it really wasn't a problem most of the time, & I have a decent small lathe for precision jobs. There was quite a short 'step' between the worn & unworn sections, and it was when the carriage was working over this 'step' that I got real problems. One job which comes up quite often for me is boring out and sleeving long propellor shaft bushes; these can be up to 11" long, and with that length of boring bar the effect of running over the step was greatly exaggerated. I got round that one by routinely using a floating adjustable reamer to finish the bores.
Having said that, the wear wasn't the principal reason for changing, the real reason was that I was offered a lathe which should suit my purpose much better, locally and at a pretty good price and almost incidentally with much less bed wear.

Tim
 
Tim yes there is a little fish eye effect on my camera


So you think I should just use it as is and see if I run into problems?

I build cars that can hit near the 200mph range so I am a little OCD about ware on parts.

Anyone else??

Thanks
 
I hate to say this, but I wish you'd turned a test bar before you took it apart.

Measuring taper (or hopefully lack thereof) on the finished work is the best judge of a machine's condition in my opinion, because that is the "output" that needs to be held in tolerance. Simply finding the machine out of tolerance does not necessarily guarantee an equally out-of-nominal part.

So, my advice: reassemble, turn a test bar, and report back.

* test bar in my definition is essentially a bar held cantilevered in a 3 or 4 jaw chuck, something on the order of 1-1/2" dia x 5-6 inches of stickout. Turn with a very very light finish cut with a round-nose very sharp HSS tool, like .002" diameter reduction and enough to clean up the surface. Use power feed. Turn as close to the chuck jaws as you dare. Surface finish should be very nice. Mic 3 spots on the bar, (end, middle, other end), to see what you are getting, the change in diameter is what you are looking for....

As I posted in another post, there are a number of functional relationships that have to be maintained when you grind the lathe bed:

- headstock spindle and tailstock coaxial
- headstock drive to feed & thread box input - end gear clearances
- leadscrew, feedrod and clutch shaft to apron alignment
- inboard (gearbox) and outboard supports for leadscrew, feedrod and clutch shaft
- carriage feed pinion gear to gear rack - gear clearance

Also, as I stated in another post, IMHO, the cleanest application (resolves the most number of functional relationships) is if your headstock is aligned by the carriage V and flat ways, grind these and the tailstock ways at the same time, the same amount vertically downward.
 








 
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