Myford super7 saddle / tight toward tailstock

You should find the top of the front shear and under the back of the rear shear. The forces of turning push the carriage down on the front shear and pull it up on the rear. Measure the thickness of the front shear along the front edge of the front shear. Maximum wear will be 4 to 6" from the headstock.

Vertical movement of the saddle will occur but remember the shims are laminated with 0.002" elements, so if tight and you remove just one shim laminate you will have 0.002" lift which is OK.

My previous S7 was a well-used buy and initially displayed similar symptoms. Quite a bit of wasted time was spent trying to adjust the gibs before discovering Geo Thomas' book and his observations on Myford gibs. He described the (quote) "wedging action" of Myford gib adjusting screws and how modifying their ends could remedy certain problems. His drawing showed:-

I can't claim to have produced perfect hemispheres on the ends of the adjusting screws but rounding them off reduced, albeit not eliminated, the tightening-up of the saddle along the bed.

(The V-shaped indentations in the topslide gibs were far from smooth - showing considerable scoring. When they were cleaned up and the topslide adjusting screws rounded - movement there was much improved).

I think Geo Thomas also advocated dowelling the gib to the slide body, to prevent any axial movement of the gib relative to the slide body. I have done this to my topslides and it does make a difference.

Alan

Edited By Alan Jackson on 20/12/2021 17:08:23

Hi all -

I do plan to dowel the topslide and cross slide Gibs, but the saddle Gib - from what I can tell - is dowelled already. The third gib screw inserts into a hole on the gib strip, thereby locating the gib strip and also, one would think, reduce movement when adjusting the others. This is lacking on the top and cross slide, which is why I plan to dowel them as per GT's book (which I must say is probably the best book i own, highly recommended!!).

Whilst searching thro' back copies of M.E. for an article, I happened upon this entitled "Lappiing - Machining to Millionths" from No. 1996.
I don't think there's a copyright issue with me reproducing this short extract.
If the methodology works as described it could be a simpler approach.
The volume and date can be taken from the image below. If you want to pursue the idea & don't have the original mag issue then I think you may have to seek permission from M.E. publishers for me to copy it to you. Send me a PM if so.

I agree and have also done my saddle.

I think that later machines had the hemispherical ends to the gib screws as standard.

Good afternoon all

I'm still working on this and have recently broken down the entire saddle / cross /btop slide assembly and cleaned everything thoroughly including the screws.

Whilst doing this I was considering the cross-slide Gibs and reading a copy of Connelly's scraping and rebuilding machine tools book (which is very useful!). It seems that the cross slide Gibs are 'angular' Gibs, but I've become slightly confused when considering how they were fitted and adjusted. There are cap head screws that go through the cross slide table and into the Gibs - but also gib adjustment screws on the side of the cross slide table. When I disassembled the cross slide, the cap head screws were very tight, which I imagine would have the effect of sucking the gib strips up to the bottom side of the cross slide table. With that being the case, how do the gib adjustment screws on the side of the table have any effect? Are the cap screws 'locking' screws, in that you adjust the gib strips using the screws on the side, and then lock the gib strip in place by tightening the cap head screws?

Cheers!

Yes inded they are "locking screws" however they do need to be nipped firmly so that any subsequent tightening after the gib screw adjustment has been made is minimal. A matter of juggling them as it were.

Edited By KWIL on 03/01/2022 17:36:24