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Gib adjustment boring mill

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
We've found the headstock and table can move a thou or two without registering on the DRO. Seems like the problem is the feed screws are slightly tipping the table or headstock on the ways. The DRO scales are furthest from the spindle and the screws are nearest. That's the theory anyway.

This is on a 1979 Kuraki KBT1003W with large box ways. The gib adjustments are easily accessible. How do you tell if they are adjusted correctly on a larger machine like this?
 

Richard King

Diamond
Joined
Jul 12, 2005
Location
Cottage Grove, MN 55016
I looked it up and found this one so people know what you have. Looks like a nice machine.

I would first off clean the ways then remove the way wipers top and bottom of the head and see if I could slide in any feeler gages in between the ways of column and head. Or with a helper mount a mag base on the head with indicator on column close to the head. Then feed it up and then feed it down and look for the lost motion. On the movements lock the head too. If it is a lot you may want to pull the gibs and relieve scrape the middle 40% and 1/2 moon the whole thing. . Garwood knows how to scrape as he hosted my Make a Wish class we did a few years ago. That should help a lot and if it still rocks then it's the headstock too. Be sure not to get them too tight as you have to have a gap for oil. Have you checked the lube system I would think .001" to max .0015" minimum lost motion or gap with way oil on ways. Get it to tight and it could score. I see what you mean about the multiplication of the error the further you go out from the ways. May have move the DRO head closer to the scale.

PS. Be sure to stone it good to remove any burrs and run the stone on the sides of oil grooves too.
 
Joined
Apr 19, 2006
Location
Manchester, England
I’ve only just seen this post so sorry to contribute so late. First of all I wouldn’t be too bent out of shape with a 0.001” deflection. I like to see some very slight movement. I’ve also seen quite a few fire ups on cast iron ways when the operator has got carried away with adjustments.
My adjusting technique was to get a helper to wind the table away from me slowly as I pushed the gib in by hand until it felt snug. Then I’d wind the table one way and then the other looking for a slight amount of movement on my DTI. No movement and I wouldn’t be happy.

Regards Tyrone.
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
Good advice from both Richard and Tyrone. I would add that you can run a little more on the snug side if you use a good amount of oil. If you're on the dry side you want to be a little looser on the gibs. This is one of those areas that penny wise, pound foolish definitely applies. I added electric oilers to several HBMs, and always ran them pretty liberally. One of the places I worked, the miserly owner decided it was costing too much in oil. He turned the oiler down on the machine. Within a month or so there was a large gall and scoring on the ways - that had previously been pristine.

I used to stick indicators on either end of the table and register them on the side of the ways and reverse the table back and forth as I snugged up the gib. When I got down to less than a thousandth on reversal I'd then check free movement at both ends with a small block of wood as a pry bar. If they wouldn't go that low without getting too tight or if they weren't the same at both ends, time to investigate the gib for uneven wear as Rich mentioned. If they were the same at both ends I'd snug up further on the gib until I felt drag, then back off just a bit.
 
Joined
Apr 19, 2006
Location
Manchester, England
I had a similar experience on a Hor bore re-build. The guy spent £35,000 on a pre-owned 5” spindle machine, probably another £10,000 on the installation and re-build but jibbed at £600 for an automatic pump for the way oil. You know what came next, a fire up on the cross travel ways.

Regards Tyrone.
 

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
Rich- That is the exact same machine. Thanks!

Tyrone- That makes perfect sense and easy to check.

Ekretz- This machine has auto way lube pumps on the saddle and one just for the vertical ways and quill. I lube the hell out of it manually as well. Oil is cheap. On my to do list is to pull the auto oilers apart, clean them out and replace the filters. They seem to be working, but I like to do this as PM on all my CNC's and this uses the same kind of system they do.
 
Joined
Apr 19, 2006
Location
Manchester, England
Rich- That is the exact same machine. Thanks!

Tyrone- That makes perfect sense and easy to check.

Ekretz- This machine has auto way lube pumps on the saddle and one just for the vertical ways and quill. I lube the hell out of it manually as well. Oil is cheap. On my to do list is to pull the auto oilers apart, clean them out and replace the filters. They seem to be working, but I like to do this as PM on all my CNC's and this uses the same kind of system they do.
Regarding the deflection of the spindle frame ( headstock ) - they are prone to differential wear on the ways. Most spindle frames have a long tail bracket hanging out at the back. With the best will in the world it’s really difficult to position the balance weight chains in exactly the right place. As a consequence if the spindle frame gibs aren’t adjusted on a regular basis the back end can begin to droop. Modern machines are prone to this because of the use of relatively soft anti-friction material on the spindle frame ways mating with ground ways on the column.
You can get into a situation were the spindle is no longer square to the column and parallel to the table top. Correcting this error was a common procedure back in the day when I was on the tools.

Regards Tyrone.
 








 
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