# Gibs on a 1956 south bend mill



## richl (Nov 29, 2017)

A couple of questions, I have this mill tore down to the saddle, and that's coming off tomorrow too. I'm going a bit slow, I'm a tad bit timid on what I am finding and watching the h and m videos on Bridgeport restoration on utube. 
The original specs said way oil or grease could be used, previous owners choose grease, all pathways were caked shut with hardened grease, I am going to use way oil.

Pics are wonderful, so here are a couple. This is the back side of the gib , it sits against the table and the saddle.






I hope in those 3 pics you can see the flow of the oil from the zerk fitting, to the bottom of the table ways and thru the hole to the gib  and than to the side of the table ways
Question:
Installing the the gib, do I install the gib soaked in way oil, or is the path thru the above holes enough.

Next question, in the h and m videos, they show how to adjust the tension on the half nut to pick up slack in the wear of the screw and half nut. I watched a video by Keith fenner and he made the non adjustable half nut on his Rutland lathe adjustable by drilling screws into the side. My situation is a bit different, my half nut is solid brass, 1 piece. Is it worth splitting the half nut and drilling and tapping for a couple screws to adjust?.

I'd appreciate anonymous thoughts on this









If splitting the half nut is not a good idea, is there another way to get some adjustment on the half nut?

Thanks
Rich


----------



## markba633csi (Nov 29, 2017)

How much backlash are you seeing with the brass nut?  Most machines have some. An older machine may have 50 thou on the dials(mine does)but still be useable, especially if you have a DRO (mine doesn't,yet)
Mark S.


----------



## 4GSR (Nov 29, 2017)

I would not split the nut. The reason being, is if you do so and get the slop to near zero, it will become dead tight 5" of travel either direction.  Then you have to go in and put more slop into the nut, so you can get the table to travel further.  I would just leave it alone unless there is lots of slop.  Say anything over .030".  Then it would be advantageous to make a new nut.  New project to add to your lists. 

Oh, going back together on the gibs and slides, apply generous amounts of your favorite oil to all surfaces, bearing or not.  Yeah, get rid of the grease!  I have a project Bridgeport clone that is caked up in nasty grease!  Not looking forward to cleaning it up. 

Ken


----------



## Downwindtracker2 (Nov 29, 2017)

I 've seen a few of ways to take up backlash on nuts. On your machine I would run a "jam nut" up to the block ,adjust it to  an acceptable backlash, then use a small screw through the "jam nut" to lock it.


----------



## markba633csi (Nov 29, 2017)

Good idea for the jam nut- If you were to make a whole new brass nut you would probably discover you need new screws also, for the
reasons Ken mentioned above.  Another can of worms.
Mark


----------



## richl (Nov 29, 2017)

Thanks for all the input, much appreciated. I really like the nut idea, sounds very doable and not a project where the table and saddle need to come off.

 (Before cleaning)Backlash on the x axis is probably only in the 10 thousands area, so from what you guys are saying i should be good for a bit. I use igaging dros so it is not a big deal.

I did the saddle today after working on the roof on the shop. 3 plus hours of cleaning hardened grease and swarf out of the saddle, the y axis screw and nut chamber were almost completely encased in it... thank God for earth magnets, I was not putting my hand in that trap lol the y seems to be much tighter that before only a few thousands run out after I put here all back together, it was worse before... not sure why that is. The ways, gib and all oil passages were completely caked in dried grease so maybe that was a problem.

I very liberally coated everything in way oil before assembly. I'll do the xmaxis table tomorrow, I'm bushed today

Thanks again, I feel a Little better now.


----------



## markba633csi (Nov 30, 2017)

Everything works better when you hang out at Hobby-Machinist.Com!  (sounds like a commercial)


----------



## richl (Dec 1, 2017)

Ok, she is all back together. A couple of things I am noticing.
Y axis. The gib has worn down some. In order to make it solid enough to not be able to rock the table it needs a 6 thousandth feeler gauge placed in it. Would it be acceptable to put a 10 thousandth feeler in or some other type of shim? Making a new gib maybe an option, just not right now. Shim the entire length or is one in the center enough? The gib  is about 10" long. 

Y axis has about 4 thousandth runout
Y axis appears to be in the 8 thousandth area
Noticeable grooves in the ways for the y axis. That was from all the grease and chips... it's a darn shame. I'm looking to learn scraping, though I want to learn on practice stuff, not my mill.

I'm happy with the machine as it sits, just looking to make it better. Way covers go on today, reinstall the dros, get the table covers on. Reinstall vise. Tram. Make chips

Rich


----------



## richl (Dec 2, 2017)

Any input to my last post?
I just would like input on how to shim the y axis gib.

Thanks


----------



## Silverbullet (Dec 2, 2017)

If your going to shim it ,I'd first make the gib flat and parallel. You can do it with Sand paper  flat on the table and grit upwards rub the gib full length to get the high spots level . Then polish it smooth and add the shim . Clean it well .


----------



## richl (Dec 14, 2017)

This is a video from h and w on youtube about installing a shim on the gib for a. bridgeport mill.


----------



## Dhector (Dec 14, 2017)

I did this to mine and it seemed to work VERY well. Mind you I am a novice with machining but this made a world of difference on every aspect of mill use in my specific case. Also, if you have an idea of what size feeler gauge that may help you, I'd be happy to send you one since I have an entire set, minus one I used on my machine. I also have a sheet of .010 shim stock if that would help you to.




Dhector said:


> I ordered a set of 12 in long feeler gauges and cut one to fit in between the gib and the saddle(where the rubbing does NOT occur) and it took up the slack in it. It actually tightened up well. Well see if it lasts. Anyway, its way better than before. Going to go play with it now! Thanks.


----------



## richl (Dec 15, 2017)

Agree, I placed a temp feeler gauge .010 in and it does seem to be doing the job. I have not been using the mill much the last couple of weeks, been distracted on Christmas projects. I saw the h and w video yesterday while roaming around on utube for other projects. They came out with that video on dec 07 2017, i guess they knew I needed a little guidance
Nice to know that a new gin for the y axis is not absolutely required.

Thanks for the offer dehector, I think I'll just pick up some myself, i have a couple projects i can use the rest on.


----------

