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Part is loosining up between centers

Gsharp10

Plastic
Joined
Jan 22, 2018
Hi,
I have an old Brown & Sharpe #4 cylindrical grinder. Recently we noticed the part is starting to chatter. Upon
closer examination we found that the part is loosening up between the centers even when the tailstok is locked.

We are grinding 30 inch long by 2.5 inch diameter CRS and the part is steady with no deflection (no steady rest needed).

We took the handle assembly off the tailstock and found there are cylinders and cams that move when the center shaft moves. There are some broken parts in there, could be an oiler.

Here is my question for you guys. Do I need to get the ID of the tailstock honed true and get the center shaft chromed and ground, or do you think its the handle mechanism that is worn and needs parts?

Total refurb of the tailstock is $5,490.

By the way I do have a spare B&S #3 tailstock that is identical to #4, but the bed of the #4 is different so centers don't align.

Thanks,
Gary
 
I'm not clear on the origin of the looseness. Are you saying the tailstock plunging center is loose within the tailstock casting, or is it being pushed back because it's not locking correctly?

If the center body is loose in the tailstock, then yes, repair that the best way possible. On the broken parts, post pictures of them, maybe someone can identify what they are.
 
Hmm, I'd be surprised if it's the tailstock. Check your workpiece centers and make sure they're correct. If the angle of the center in the work isn't correct it will wear quickly and loosen up. And the tailstocks of O.D. grinders are generally spring loaded for correct pressure but often the spindle is then clamped, especially on larger machines.
 
In my ignorance I also thought that all the centers would be spring loaded and not clamped.
If the center is clamped, I would be extremely careful about any heat buildup in the part: if you let the part warm up, it will push the centers away and it will be loose as soon as you allow it to cool down some.

Paolo
 
I found this parts manual on an 1926 machine. Page 12 shows the tail stock...http://vintagemachinery.org/pubs/2185/24279.pdf does this look like yours?

A machine almost 100 years old ?? It would make sense many parts are worn out and if your mechanically inclined you should be able to take it apart and figure it out. $5400 seems high. As the others a photo would help a lot. I am a professional machine rebuilder and after you take it apart measure the ID of the TS quill hole with a ID or telescope gage, mike the quill, check the spring. In the manual it shows a cam under it with springs .

Here is a 1944 machine....It is an operators and parts manual. On page 89 it shows a parts breakdown. It appears to have tapered bushings on each end that can be adjusted and locked. It looks like the one John showed. I'll keep looking.
http://vintagemachinery.org/pubs/2185/23997.pdf
 
On my '47 #4 - you can use just the spring or you can over ride that with the clamp and adjust feature

I like to have it snug to turn (on white lead and two dead carbide centers) then back off that a tiny smidgen to make it reasonably free

And for me, never dry always flood
 
Yeah I should probably clarify. When I said I'd be surprised if it was the tailstock, I meant surprised if it was some sort of mechanical damage to the tailstock that was causing the problem. Center wear or part heating causing expansion then cooling and getting loose are good avenues to investigate. And I fully agree with John - absolutely always use flood coolant whenever possible if it's more than a dust grind.

Tailstock bore or spindle wear will probably not be a likely cause of chatter unless it's severe wear since the spindle can be clamped tight.
 
Hi and thanks for all your replies especially Richard who sent me that awesome parts manual. I've had my grinding shop for 40+ years and this is the first parts have loosened up between the centers. The part is normal tension between the centers, but after a few revolutions it is so loose you can actually spin it with very little resistance and it is really..really loose.

I'm stumped. I certainly don't want to shell out $5,000 and find out it's something other than the tailstock. Headstock and tailstock are clamped tight on the bed. I just don't know.

Thanks,
Gary
 
Is there anything in the tailstock that could be adding friction, so that if the center is bumped back it might hang up and not immediately return? How much does it wobble in the bore?
 
At this point I think I would slap a couple indicators on the various parts of the machine with movement potential and see what exactly is moving. After that worry about what you need to do to remedy the situation.
 
Really, really loose is good. That means something is moving a lot. That is much easier to find than just moving a little. Try eKretz's idea about indicators on parts until you find whats moving. A possibility would be the entire tailstock. The clamp is gunked up so even though the nut is tight, the clamp mechanism isn't being tightened.
 
Are the incoming part centers good?
Once had a similar problem and asked the guy at the hass to put in a g04 at depth,
He thought I nuts, had never heard of such a thing, and then,,,
This most likely a fluke and not your problem as I am sure you have looked at initial and finish contact on the parts centers.
Bob
 
Probably not a problem here, but I have had unusual drive dog set ups for odd parts. Have had them bind slightly and move or push on the part. Also had the dog arm rubbing slightly on the head stock. Guilty of not making sure the part was free through the entire rotation.

Bill
 








 
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