automatic feed slip? help

[Speedy]

I cannot remember in terms of adjustment how to fix this below symptom.

I have a full size engine boring bar, kwikway.
when I engage auto feed the machine will bore into the cylinder smoothly, but as it gets further down the cylinder the column will drop with a thud and leave a small ridge in the cylinder uncut.

is this a symptom of the column gib bearing being too loose?

 

[Hopper]

You might try posting on Practical Machinist forum. More guys on there working with fullsized automotive machine tools like the Kwikway.

 

[Dalee]

Hi,

Been many years since I owned one of those, got rid of it because I wasn't really using it.

It's possible the gibs are loose and the cutting load is slowly building up until the screw and nut push it down with a thunk. But it should show poor finish also. It is also possible the screw is loose and riding up on you until it thumps itself down. Worst case is a worn nut and screw.

You will need to track it down to know for sure.

 

[Speedy]

thank you Dalee, and hopper.

I went with the loose gib idea and broke out the measuring tools, I had 1.5 thou of play. seemed loose to me and found the manual online. it calls for .0002 back/forth play for total of .0004. so I was very loose.
after fiddling with it for awhile I got it in spec and had to compromise being tighter in the lesser used areas. slightly worried I am slightly to tight but will go with it.

runs great now

I could only make one pass on my test cylinder as its to thin now, but I noticed at the end it left a portion uncut. I don't know how I could pull the bar so far out of alignment with adjusting the gib so I am hoping my prior attempts of boring with the loose gib was the culprit.
measuring all the areas that did cut, I am on the money, including the lower portion around the uncut area. will see if my local bike shop has a old cylinder and will test again to be certain.

 

[rlukens]

Not being a wise ass here, but 1.5 thou (.0015) is a lot of play. Specs call for .0002 - .0004 ? Maybe time to stone or scrape the ways.

 

[Speedy]

no worry, in my previous post I did state I got everything in spec and the ill symptoms are gone.

just tracking down another cylinder to confirm its boring true. and it should..... I hope.