Where do I look for someone to grind my bed

[Vince_O]

Ok guys I need some help with my 9a SB. I dont have much in it but Ill never get one this cheap again, so I need to fix the ways on it. Now keep in mind Im making parts and such for garden tractors and the last time I checked they dont need them on the moon, but I want to do the best work I can and do it right. I found a post last night of a place that Richard had sugested to another member in my area, but its about 7 hours one way for me but shipping is not out of the question. Where or what type of busnesses do this type of work?



https://www.youtube.com/watch?v=Nky_0Z4dcTg

 

[pjf134]

Vince,
Cut a test piece using a round bar and measure it. The only thing that rides on the flat that you are measuring is the tail stock. The carriage rides on the v ways. Make sure the lathe has no twist in the bed before using the test bar and is level. Near the headstock has the most wear because that is where the most cutting takes place.
Paul

 

[4GSR]

Your bed obviously has lots of wear from the indication of your check you made. Generally you put the dial indicator point on the unworn portion of the bed between the way bearing surfaces. I'm sure on the 9" SBL, the tail stock ways have little wear from use in comparison to the ways the carriage runs on.
As for grinding the ways, it may be much easier to find some one local that has a large capacity CNC bed mill that is in new shape to use. Your bed does not have harden ways, they are soft, that is some of the reason of the wear you see. This would be a easy fix doing on a CNC mill. The precision involved CNC mill verses a way grinder will not be notice from a HSM standpoint. In fact, I would not be able to tell the difference! You'll have to remachine the underside of the saddle too, and shim up the saddle for proper alignment using Turcite or Moglice for proper alignment.
It would be very difficult to refit the saddle to the bed after the mass amount of material that has to removed from both the saddle and bed. You're talking about .015" to .020" off of each way surface on the bed and I suspect the carriage already has double the wear of that of the bed which would put it at about .030"-.040" off of each way surface. This would mean having to add a shim thickness of about .045"-.060" thick to bring everything back to normal.
Anyways, your call on what to do, just my suggestion of what direction to take.

 

[chuckorlando]

Thats what our instructor suggested for really worn ways. CNC them back straight then shim and scrape them

 

[keithmifflin]

I have to agree with 4gsr that after you grind the ways you need to refit every thing to it and that can get into a lot of time and cost. You would be far better off just finding a used but decent bed. Southbend beds are plentiful for your model of lathe. Check Plazza Machine in I think Vermont he has a large inventory of most every brand of lathe or mill.
Keith

 

[Shadowdog500]

Out of curiosity how much does it cost to have the ways done.

I usually factor on the cost and time to fix something vs replacing something. I'm wondering if it would be better and less expensive to find a better bed or a different lathe.


Lathes can can be found, and unless the one I had was unique, or a family heirloom, I probably wouldn't spend more than its worth to fix it up.


Chris

 

[12bolts]

Vince,
Is that your lathe in the video?
Using the carriage to traverse the DI will not show all your wear problems. eg Imagine if the bed were tapered uniformally in height from Tailstock to Headstock. The dial indicator would show Zero deviation from right to left.

Cheers Phil

 

[astjp2]

I was quoted 1500-2000 to plane the ways, they are not normally ground from what I have seen. I bought a bed cheaper than what I could get mine fixed for. Tim

Out of curiosity how much does it cost to have the ways done.

I usually factor on the cost and time to fix something vs replacing something. I'm wondering if it would be better and less expensive to find a better bed or a different lathe.


Lathes can can be found, and unless the one I had was unique, or a family heirloom, I probably wouldn't spend more than its worth to fix it up.


Chris

 

[Vince_O]

Phil

How should I check it, other than cutting a test rod?

 

[4GSR]

Vince,

The method you used is valid, but the dial indicator point should be placed on the non-worn portion of the lathe bed between the ways. What this will tell you is how much drop you have in the carriage or saddle while moving up or down the bed. This measurement will not tell you the exact wear or the amount of wear you have, but is a indication there is wear. By triging out the angles of the vees, you can come up with a calculated number that would give a ball park number of how much wear you really have. The sides of a vee normally wear by the same amount, as I have found, on many lathe beds I have dealt with in the past. What I have notice is that the front vee will wear slightly more than the rear vee does. The immediate reason for this is cutting tool pressures localized to the front/left side of the saddle.

The test bar will tell you how much taper there would be in cutting a diameter, when cutting between centers or cutting without a center in the end of a part, neglecting "push off". If the bed is in good shape, little or no wear, it would tell you if there is an alignment problem somewhere.

Both are good practices for indication of something is not right. Is one better than the other? No. they both have a purpose. The test bar will tell you if you have an alignment problem, the indicator on the bed will tell you you have wear. The test bar may not tell you if there is any wear.

The only real way to determine how much wear there is on each way surface is to put it up on the machine tool that is going to re-cut the surface straight and flat again. And by using a indicator, indicate the bed in so it is running straight to all planes, then indicate all the areas that have wear for high and low points in 0.001". This will be as close as you are going to get for determining wear on a bed.

EDIT...You could use a straight edge laid against each way surface and use feeler gages to determine the amount of wear. But man handling a 50 lb straight edge is not fun!