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| andyf:
If you have not only the screws but also a pin to locate the gib, Peter, you probably won't need a plate or those screws and washers. I made an apron with a half nut to replace a solid nut on a little lathe, and that holds in place very well with the adjusting screws only: < http://andysmachines.weebly.com/a-half-nut-for-the-perris.html > I did make decent sized dimples, though, following the instructions which which came with the kit of parts for the lathe 40 years ago: "The way to do this is to lock the outer screws, remove the centre ones and using a hand drill (not electric) with a small twist drill which enters the hole, rotate a few times to cut a dimple, clean out the hole, replace the screw and do the same with each of the other holes in turn". With gibs on cross- and top slide dovetails, where the gibs move with the sliding, rather than the static component, you sometimes have to watch that the screws don't push the gib down the slope of the dovetail so that it jams against the static part. Andy |
| PeterE:
Hi Andy, About the gib strip; In most cases I would go with what you are saying, but in this case the gib strip is almost triangular in shape, that is, the "pocket" in which the dove-tailed half nuts run have only a 60 degree dove tail to the left (in my picture above). The right side is completely upright without dove tail. So, the washers are used to hold down the gib strip and keep it in place while the set screws provide the sideways movement tightening and removing the play. Due to this I would be quite unsure that the gib strip would stay in place by the dimples and pin)-s) alone. There will be some force from the feed that I think will try to trwist out the half nut if going gets rough. That is why I am thinking of replacing the washers with a longer keep plate. Then I think only one pin would be enough to keep the gib strip from falling out and good dimples for the set screws. As work slowly advances, I found that the way of setting/removing the play between the x-slide and the bed had also loosened. It must be due to the fact that the securing screws cannot be tightened hard enough and still provide the proper amount of "play" (there shouldn´t be any and still the x-slide should move). If I take the set screws away and just tighten the fastening screws the x-slide i locked solid. In a way this is good as I then can put a shim or packing to get the "play" where I want it. :scratch: Question: As I do not have any shim plate, can I use ordinary printer paper slightly oiled or should I try to find proper brass shims of various thicknesses? Paper is easy to use as one or more sheets are required and is readily available. Work continues ... :dremel: /Peter |
| velocette:
Hi Spotted this posting on gib adjustment screws. Here is a tip I picked up to address the problem. Locking up the tight the adjustment and then remove one screw and use a hand drill the tapping size of the screw you have removed and Hand drilling the dimple and clean up is sound advice. Find a Ball Bearing that is smaller than the tapping size and CUP POINT screws. Put the ball into the hole first and secure with the cup point screw this gives you a hardened point of contact and a lot more control on the adjustment. Example 5 mm screw 4.2 tapping 4 mm or 5/32 ball I Completed this mod on an X2 mill when I purchased it and very pleased with the result :mmr: Eric |
| andyf:
Got that, Peter. Sieg have odd ways of doing some things, don't they? I believe from the Yahoo 7x12 Group that shimming the gibs between the saddle "side plates" and the underside of the bed is a lot better than Seig's way of some screws pushing up and others pushing down. Paper would probably work, but you might also consider cutting up beer/pop cans, the aluminium trays used for some ready meals and takeaways, and aluminium cooking foil, to build up the thickness you want. Andy. |
| loply:
As somebody who has made about three different sets of gibs for each of the various parts of a 7x12 I can recommend replacing the main saddle gibs with new ones which set with screws. I would advise against using shims as you will find the saddle is not machined parallel to the underside of the lathe bed. If you use shims you will need to shim the front and rear of the gib seperately to achieve proper contact, which is decidedly fiddly. The best method is to make a new gib strip which is larger than the original, and insert into it two rows of small grub screws with faced/flattened ends. By adjusting the screws front and rear you can tilt the gib strip back and forth, as well as adjust it's "height" ie tightness, and can use permanent marker to test until you achieve good contact. There is an example of this on the website http://www.toolsandmods.com/lathe/mini-lathe-saddle |
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