On Tuesday 06 May 2014 12:33:44 Steve Cranage did opine: > You'd be surprised what a standard machinist level can do for you. I > have a Starrett master precision level as well as a ~6 inch Lufkin > basic machinist level without any graduations except the center. > Honestly, I can get about the same level out of both of them, if you > have a good eye for symmetry (dividing the bubble) you can too. OTOH, > forget the Chinese knock-offs of the Starret Master Precision. The > vials in those are useless for anything other than woodwork maybe.
I have an ancient level thats pretty precise. Looks like an old mantel clock with its big round vial carrier that can be turned, with vernier markings for fractional degrees. One end of the long base had some pretty bad rust on it when I gave the guy $2 at a flea market. I've cleaned up the base some on a sheet of 600 grit w-d on a surface plate, and have tried to adjust the needle to compensate, but the best I can do for a level reference is to turn it from end to end. If I get the same reading mirrored, I figure its good enough for the girls I go with. That is also my std test at the store when buying a level, it had better give mirrors of the error of the surface I set it on or it doesn't come home with me. My son, who has done quite a bit more carpentry that I have, went out and bought the fanciest 4'er, wooden with inlaid brass corners. Got it home & no bubble in it was closer than 1/2" in that 4 feet. > > From: [email protected] > > Subject: Emc-users Digest, Vol 97, Issue 19 > > To: [email protected] > > Date: Tue, 6 May 2014 15:22:32 +0000 > > > > Send Emc-users mailing list submissions to > > > > [email protected] > > > > To subscribe or unsubscribe via the World Wide Web, visit > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > or, via email, send a message with subject or body 'help' to > > > > [email protected] > > > > You can reach the person managing the list at > > > > [email protected] > > > > When replying, please edit your Subject line so it is more specific > > than "Re: Contents of Emc-users digest..." > > > > Today's Topics: > > 1. Re: Question re crooked headstock (Gene Heskett) > > 2. Re: Question re crooked headstock (Gregg Eshelman) > > 3. Re: Question re crooked headstock (Gene Heskett) > > 4. Re: Question re crooked headstock (andy pugh) > > 5. Re: Question re crooked headstock (Eric Keller) > > 6. Re: Question re crooked headstock (andy pugh) > > > > ---------------------------------------------------------------------- > > > > Message: 1 > > Date: Mon, 5 May 2014 22:33:09 -0400 > > From: Gene Heskett <[email protected]> > > Subject: Re: [Emc-users] Question re crooked headstock > > To: [email protected] > > Message-ID: <[email protected]> > > Content-Type: Text/Plain; charset="windows-1256" > > > > On Monday 05 May 2014 22:13:12 Steve Blackmore did opine: > > > On Mon, 5 May 2014 04:48:55 -0400, you wrote: > > > >I suggested that a heavy steel bar, a 1x6 wide, nominally 24" long, > > > >to help stiffen it up, and was told its a never mind. By someone > > > >on this list about 2 coons ages ago. Whether I could find another > > > >at the scrap/recycle yard about 50 miles away, I haven't looked. > > > >As for added stiffness, I don't think a 1/4" plate would do > > > >anything but change the resonant frequency, probably down in pitch > > > >because its more mass than stiff at that thickness. (IMO) > > > > > > Steel plate stops the feet sinking in the wood/mdf and allows > > > shimming without it just sinking in. > > > > > > >But its certainly better advice now, having lived with it, sitting > > > >on that mdf in 2 locations now and never getting a straight turn > > > >out of it. > > > > > > MDF and just two bolts - no wonder it turns tapered :) Needs to be > > > bolted down to something rigid enough to enable you to pull the > > > twist out of the bed. It will have one - no doubt. The casting > > > weren't weathered before machining, It will have been clamped down > > > to some dubious surface, machined then ground, both releasing > > > stresses and when unclamped it twists and bends. > > > > > > My lathe came with it's own stand, it had a nice heavy cast top but > > > it was far too big for the available space, so I made my own. My > > > stand is 3" box section welded up, 10mm steel top with drip tray > > > sandwiched between lathe feet and top. I put a shelf in there and > > > it has steel panels bolted to sides and back. > > > > > > One of the best buys I made was a boxed Starrett Model 98 level, > > > only paid ?50 for it and some other tools from a Snooker table > > > repairers/installers that shut down :) Multiple graduations are 5 > > > thou per foot and you can get damned close with a good level alone. > > > > > > My method is use the level to get it even at headstock and tailstock > > > ends, then use taper turning test to get it spot on. My lathe/stand > > > isn't level, it tilts forward and towards the tailstock, otherwise > > > coolant doesn't drain - but it has no twist so turns true. > > > > > > Steve Blackmore > > > -- > > > > I'll restart my search for a suitable piece of 1 by steel. The first > > place I'll look, after I get my GMC inspectable again (terminal rust > > of rocker panels, minor crack in windshield its had for a decade) has > > about 50 kilotons of magnetic scrap. They surprised me several years > > ago when I was lamenting that what I really needed was a solid block > > of alu I could saw the makings from. He went behind the scales & > > came out lugging one piece, about 50 lbs, roughly 6" square > > cross-section and around 2 feet long, obviously band sawed from a > > much larger 6" thick sheet. $1 a lb, I still have perhaps 10 lbs of > > it left. Not very hard stuff, a bit gummy to machine, but hey, it > > works. No level that accurate though. Set it on 3" studs, nut and > > washer below, nut and washer above, using them for jacking screws I > > could pull it whichever way reduces the error. Or bolt it down on > > shimstock. That would be more rigid than 1/2" studs, but that stuff > > is hard to come by these days, as the only old chevy's with Christian > > Science oil are the ones you see at antique car shows. And the last > > mechanic that knew how to fit chevy's rods dies in the 70's. :) > > > > Thanks Steve. > > > > Cheers, Gene > > > > > But its certainly better advice now, having lived with it, sitting > > > on that mdf in 2 locations now and never getting a straight turn > > > out of it. I have looked carefully at where the headstock is > > > sitting on the bed, and can't see any evidence of debris holding it > > > apart anyplace. But that only says I can't see it even if its > > > there. > > > > I had two 7x lathes. One was an early Grizzly import, serial number > > 346 IIRC. The thing was a cast iron turd. It had been abused > > (apparently with hammers etc.) by previous owners. > > > > I took it all apart, repaired the damage, did a few modifications, and > > made it into a usable lathe. > > > > Its largest problem was one corner of the headstock had been dinged > > some time after its bottom had been machined, leaving a raised edge. > > Another problem was the edges of the three bolt holes in the bed were > > raised. A file and a countersink took care of those and a rag wiped > > off the pieces of crud that were trapped between. After that that > > lathe cut very well. > > > > Didn't help the crude SCR chopper driver and its lack of torque at low > > RPM but it did the jobs I needed it to do. > > > > The other one was a Homier, one of their early imports, though much > > much later than when Grizzly started. > > > > There's a version of the 7x out there which is quite a bit higher > > quality than the usual version. It has a double ball bearing on the > > carriage wheel shaft, the apron is thicker to accommodate the > > bearings. The saddle is rectangular, heavier than the other version's > > H shape, and machined all over. It also has four headstock bolts VS > > three, way wipers on the saddle and an adjustable nut with a set > > screw in its end to take up any axial movement in the leadscrew. > > > > The original Homier 7x was that version and it was pretty much ready > > to go out of the box. > > > > > > --- > > This email is free from viruses and malware because avast! Antivirus > > protection is active. http://www.avast.com > > > > > > > > > > ------------------------------ > > > > Message: 3 > > Date: Tue, 6 May 2014 08:32:22 -0400 > > From: Gene Heskett <[email protected]> > > Subject: Re: [Emc-users] Question re crooked headstock > > To: [email protected] > > Message-ID: <[email protected]> > > Content-Type: Text/Plain; charset="windows-1256" > > > > On Tuesday 06 May 2014 08:00:29 Gregg Eshelman did opine: > > > On 5/5/2014 2:48 AM, Gene Heskett wrote: > > > > But its certainly better advice now, having lived with it, sitting > > > > on that mdf in 2 locations now and never getting a straight turn > > > > out of it. I have looked carefully at where the headstock is > > > > sitting on the bed, and can't see any evidence of debris holding > > > > it apart anyplace. But that only says I can't see it even if its > > > > there. > > > > > > I had two 7x lathes. One was an early Grizzly import, serial number > > > 346 IIRC. The thing was a cast iron turd. It had been abused > > > (apparently with hammers etc.) by previous owners. > > > > > > I took it all apart, repaired the damage, did a few modifications, > > > and made it into a usable lathe. > > > > > > Its largest problem was one corner of the headstock had been dinged > > > some time after its bottom had been machined, leaving a raised > > > edge. Another problem was the edges of the three bolt holes in the > > > bed were raised. A file and a countersink took care of those and a > > > rag wiped off the pieces of crud that were trapped between. After > > > that that lathe cut very well. > > > > > > Didn't help the crude SCR chopper driver and its lack of torque at > > > low RPM but it did the jobs I needed it to do. > > > > > > The other one was a Homier, one of their early imports, though much > > > much later than when Grizzly started. > > > > > > There's a version of the 7x out there which is quite a bit higher > > > quality than the usual version. It has a double ball bearing on the > > > carriage wheel shaft, the apron is thicker to accommodate the > > > bearings. The saddle is rectangular, heavier than the other > > > version's H shape, and machined all over. It also has four > > > headstock bolts VS three, way wipers on the saddle and an > > > adjustable nut with a set screw in its end to take up any axial > > > movement in the leadscrew. > > > > I have none of that stuff. I have even contemplated making a new > > saddle, but there isn't enough bed width to make it worthwhile. But > > now that I have cut up part of that hat, I might consider bed wipers. > > > > > The original Homier 7x was that version and it was pretty much ready > > > to go out of the box. > > > > Probably even Homier's is the junk model today. Not even listed on > > their site, I just checked. I see the Bolton 11x28 is on sale now, > > $2588+ship. They don't some with any "accessories" though, so first > > extra is a bigger 4 jaw, and a decent tool post. $500. Or more. > > Nearly 500 lbs, should be stiffer. Site propaganda is amazingly > > devoid of real facts, mostly sales speak. 1.3 horse VS motor, 27" > > between centers, 1.5" spindle bore. > > > > Cheers, Gene > > > > > MDF and just two bolts - no wonder it turns tapered :) Needs to be > > > bolted down to something rigid enough to enable you to pull the > > > twist out of the bed. > > > > This does, of course, go against all the standard tenets of lathe > > design. Not unexpected for machines not manufactured with any > > consideration of lathe design, perhaps. > > > > My Rivett sits on two inset ball-bearings at the headstock end and a > > spherical washer at the tailstock end specifically to ensure that the > > support stand could have no influence on the shape of the bed. > > > > In the case of Gene's lathe it seems quite possible that the head > > simply isn't straight on the bed. It would be interesting to put a > > long bar in the chuck and see if it is possible to move the headstock > > about. > > > > > This does, of course, go against all the standard tenets of lathe > > > design. Not unexpected for machines not manufactured with any > > > consideration of lathe design, perhaps. > > > > > > My Rivett sits on two inset ball-bearings at the headstock end and a > > > spherical washer at the tailstock end specifically to ensure that > > > the support stand could have no influence on the shape of the bed. > > > > > > > > > I think the classical approach to machine design was to make the > > > mounting > > > > to the base flat and provide for leveling. A lathe is a compliant > > structure, so a kinematic mount doesn't seem like it would be as > > effective as one might like. Then again, the small Chinese lathes > > have the lowest standards of construction of any of the Chinese > > machine tools. They don't take them seriously. Would be nice to be > > able to get a small lathe to use on a mill table, but those things > > are basically pointless. > > > > > > ------------------------------ > > > > Message: 6 > > Date: Tue, 6 May 2014 16:22:01 +0100 > > From: andy pugh <[email protected]> > > Subject: Re: [Emc-users] Question re crooked headstock > > To: "Enhanced Machine Controller (EMC)" > > > > <[email protected]> > > > > Message-ID: > > <CAN1+YZVjm-o_6shgS- [email protected]> > > > > Content-Type: text/plain; charset=UTF-8 > > > > On 6 May 2014 15:57, Eric Keller <[email protected]> wrote: > > >> I think the classical approach to machine design was to make the > > >> mounting > > > > > > to the base flat and provide for leveling. A lathe is a compliant > > > structure, so a kinematic mount doesn't seem like it would be as > > > effective as one might like > > > > Reading lathes.co.uk (and I have read all of it) seems to suggest that > > the traditional approach was three bolts. Rivett just took it to > > extremes. The Rivett bed is basically a solid rectangular bar. > > (There is a central slot, but it is half an inch wide, and only about > > 1/3 of the total bed length.) > > > > I think that my Chinese 9x (which, actually, might be an Indian > > knock-off of a cheap Chinese lathe) has only two bolts, one at each > > end. > > > > However, I have never noticed that it turned tapered, for all its > > other faults. > > ------------------------------------------------------------------------ > ------ Is your legacy SCM system holding you back? Join Perforce May 7 > to find out: • 3 signs your SCM is hindering your productivity > • Requirements for releasing software faster > • Expert tips and advice for migrating your SCM now > http://p.sf.net/sfu/perforce > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users 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) Genes Web page <http://geneslinuxbox.net:6309/gene> US V Castleman, SCOTUS, Mar 2014 is grounds for Impeaching SCOTUS ------------------------------------------------------------------------------ Is your legacy SCM system holding you back? Join Perforce May 7 to find out: • 3 signs your SCM is hindering your productivity • Requirements for releasing software faster • Expert tips and advice for migrating your SCM now http://p.sf.net/sfu/perforce _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
