On Thursday 23 August 2012 11:18:58 andy pugh did opine: > On 23 August 2012 01:33, Gene Heskett <ghesk...@wdtv.com> wrote: > > Today as I was reassembling it and attempting to adjust the gib > > screws, I noted that the top face not only wasn't in contact with the > > bottom of the slider, the tip of it at the bottom of the carriages > > v-cut was sharper than the bottom of the carriages v-cut, so I > > purposely rounded off that edge hoping that both sides of the V would > > make contact. Such is not the case and never will be with this > > strip, it is not only about 50 thou thinner than it should be, but > > when the angled face is in contact with the V-way, its top face is > > clearing the bottom of the cross slider at a very noticeable angle of > > at least 10 degrees. > > I am not sure that the top and bottom angles matter. > My analysis of how it is meant to work is that the strip and screws is > meant to pull the slide right and down. Right against the dovetail, > and down onto the flat top face of the saddle. > > It might be worth looking at the left side of the dovetail. My milling > column dovetail had been ground to leave a high land under the > undercut, so whilst there was a nice smooth surface, that wasn't what > the head ran on. It took me quite a while with a scraper to fix that. > I already found that and ran a mill bastard over the sharp edge, rounding it over about 20 thou.
> You might also find another example of the "sharp edge into rounded > corner" problem at that left side. See above. > > The adjusting strip ought to be able to pivot to sit flat against the > underside of the dovetail. From what you say it seems like the gib or > the dovetail are not flat. That face has been lapped on a surface plate with 600 grit wet-r-dry, wet. flat lengthwise, possibly not across the width (crowned) as its difficult to hold and I don't have a jig for that. Obviously if I make the gib, I'll have to make a jig first. I get the impression the strip is rotating a few degrees on the tips of the screws, allowable because the top of the strip has wedge shaped daylight above it and the dimples for the screw tips aren't properly drilled. The contact between the screw tip and the dimple seems to indicate the dimples are too low and the screw tip is riding only the upper edge of the dimple. Vertically, the strip, if all the angles were correct, could be over 2 mm thicker. Horizontally, another 1mm would be about right. There is daylight under the gib too. Perhaps half a mm. > Personally I have never really liked the strip-and-setscrew approach, > but some very respected lathe manufacturers have used it, so it can't > be that bad. I do prefer tapered gibs though. So would I, but then we are back to beggers and horses. :) However, a new sled (Z) from scratch may be in that micromills future if I don't fall over first. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! Are you still an ALCOHOLIC? ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
