Backlash Or A Different Problem ?

P

Playingwithmetal

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I am finally getting around to tuning up the jet -15 mill drill. I have yet another problem that I could you your wealth of knowledge with. The Y axis portion of the table lies flat against the ways as it travels towards me but as I switch direction the top section lifts away from the ways and jumps if you will. It remains to keep the 1/32" gap above the ways the entire way towards the column. I am unsure what to adjust in order to correct this issues. I do not have the manual for my machine. I have a pdf of a much newer similar model but the table assembly is different. This machine is pretty old maybe 79 or so. Made in Taiwan. Any insight to this issue would be very helpful.
Thanks
Dylan

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This machine has the strangest gib system I have come across. I can adjust it so it is so tight it's hard to turn the handle and the issue is the same. Here are some pics of the gib system adjustment and the gap as the axis moves towards me is flush against the ways and as I reverse the direction the table lifts and begins its way back towards the column in the lifted position. The table is firm and strong feeling going in both directions and doesn't shake except the large jump when changing direction. I don't know what adjustments to make.

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That system is called box ways. Actually a good system when set up correctly. Try loosening the gib, and see if it does the same thing. The ''clamp'' on the bottom should keep the table from raising. There should be less than 0.001 clearance between the way and the clamp. But that does not explain why the table is lifting. The table should not lift with the lead screw even if you took the clamp off. Something is getting into a bind. Is the Y nut secured properly? Loose screw?
 
I took apart the y handle assembly to see if there was anything to tighten but nothing. Not sure where to go with it. When I adjust the gibs loose it does the same thing.
 
Sounds like you are not quite deep enough. I think you need to get to the Y lead screw nut. You may be able to access it by pulling the table off or maybe from under the machine. Not sure on that one.
 
I think your right. I have not yet taken the whole table apart. I was avoiding that until it was necessary. I will have to take the table off because the bottom of the machine is solid.
 
Sounds like a good Saturday project. :)
 
Like Jim said, get it torn down to the base and start from there. I think Jim hit it on the nail, the cross feed screw and nut are "riding high" causing the saddle to pick up when traversing the movement. These little machines don't leave you much in the way of adjustments to fix the problems.
First thing I would do is the pieces that hold down the saddle on the ways, the flat bar looking thingys that have three bolts holding them in place. Pull them off and see if there are any shims under them. If so, start removing them until you can get a .002-.003" feeler gage under the hold down and base slide. Not talking about the tapered gib here. That comes later. Once this is done, slide it by hand from from to back and see if it binds any. If not, your good for the next step. Make sure to apply your favorite oil to all sliding surfaces. Next thing to do is install the tapered gib and adjust it until the slide is able to move front to back without binding. You may wind up with the slide being loose when in the middle, this is normal for a machine that has been used for quite some time. Don't worry about that for now. Now, let's start looking at the cross feed screw and nut. ( I got to go back and look at your pictures, Ill be back to writing in a moment.)
 
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