Linley Jig Borer Assembly

[rmcphearson]

I brought home a disassembled Linley Jig Borer recently (the one advertised here on PM). When assembling both the bottom and top lead screw assemblies, without the gibs installed, the following happens: If the lead nuts are affixed firmly in place by fully tightening the pair of screws for each nut, the table assemblies slide fairly easily until about 2" from the end of their travel, then the sliding becomes pretty darn tight. If I loosen the nuts a bit by cracking the pair of screws for each slightly, the assemblies slide much more freely the entire length of their travel. I've never disassembled/assembled a machine tool like this so I'm a virgin to this stuff. Your help is appreciated.
-Roland in San Jose, CA.

 

[rimcanyon]

Suggest you post your question on the Machine Reconditioning, Scraping and Inspection forum, not in General. Most likely the machine has some wear and you are just seeing that by trying to adjust the gib screws too tight, but it may also be that you are adjusting the screws wrong and causing the gib to be too tight at one end.

 

[rmcphearson]

Again, I noticed the problem without the gibs installed.

I got to thinking about how the lead nuts are precisely located with dowels, whereas the other support for the lead screw, the spindle housings, are not. So, with the gibs installed and slightly snug, I loosened the two face screws that affix the lead screw spindle housings. And drew the lead nuts/tables all the way toward the housings which aligned the housings with the axis of the lead screws. Then I tightened the housing face screws. Now I get a nice smooth even drag all the way from one end to the other on both the X and Y. Not much wear in the ways to speak of.

 

[maynah]

Is your machine the early one with the smaller saddle or the later with a more robust saddle?

 

[Richard King]

RM...that's what I was going o tell you to do. Also usually the last couple of inches are not worn and will bind up if the gibs are tightened in the center. For everyone else Here is what we are talking about. I leave the dowel pins out and screws loose and then crank it as near to the bracket possible, then tighten them and put in the dowel pins or ream the hole and put in bigger taper pis or spring pins if they are round.. http://www.lathes.co.uk/linley/

 

[rmcphearson]

I leave the dowel pins out and screws loose and then crank it as near to the bracket possible, then tighten them and put in the dowel pins

And if there are no dowel pins on the brackets, would you consider adding some? Or just let a sleeping dog lie?
Thank you Richard.
Maynah, this is a late model with the more robust saddle, power down feed, single phase step pulley drive, and a 3 phase varidrive came with it. And the older style single slit collets.

 

[Richard King]

If there aren't any....no need to put any in. Most machine builders installed dowel or taper pins.

Your welcome. Rich