On Friday 23 September 2016 09:58:03 Dave Cole wrote: > On 9/23/2016 9:30 AM, Gene Heskett wrote: > > On Friday 23 September 2016 03:47:51 Erik Christiansen wrote: > >> On 23.09.16 01:02, Gene Heskett wrote: > >>> So what I am looking for is a bb holder that will work with the > >>> smallest QC holder. And will hold it solidly in the face of a 1 > >>> horse motor's solid torque. > >> > >> My long boring bars have flats top and bottom, so they just go into > >> the 4-way toolpost like the square TCT holders, with the 3 > >> hex-socket screws squeezing them firmly in place. Only the sides > >> are rounded. > >> > >> When a small boring bar was needed, I axially drilled a length of > >> square Al, cut a slit in one side, pushed in a small end mill, > >> squished it all tight under the aforementioned toolpost screws ( > >> with slot and one end-mill tooth horizontal), and bored away. (The > >> softer Al probably grips better than steel would.) > >> > >> The cutting tooth is small, and the holding area is proportionally > >> enormous. The screws were reasonably tight. The end mill was sharp. > >> There was no slip while making several bushes. > >> > >> Gene, is that Al bar a machinable alloy (i.e. at least a bit of Cu > >> in it), or plain toffee? That stuff can be a drag. > > > > 6061, so it's not quite as "gummy" as some I've cut. But I've now > > some bigger blocks of 7075-T651 to play with also. so the spacer > > stuffs to locate the Z screw will be cut from that. I have to get it > > about as high as I can so it clears the x motor under it. But the > > higher I put it is limited by the nut wanting to hit the swell in > > the underside of the bed. That alone assures that the screw is not > > shielded from swarf by the bed rail overhang. So I've bought some > > long bellows that should collapse enough that the saddle movement > > isn't restricted. These 6 bolt flanged nuts are a PITA, but they > > guarantee everything else will clear if the nutholder clears. The > > nut designed for a clearance hole in a piece of plate with a big nut > > would have been a much better choice. But they are hard to find of > > fleabay. > > > > At the drive end of the Z screw, its bearing holder will be bolted > > to the back of a piece of 1/2" alu plate bolted to the 3 holes the > > removed QCGB was, but spaced outward enough that everything clears > > but just barely. The big nema 34 motor will be hung on the front > > face, with two 40 tooth xl pulleys and a belt, length yet to be > > determined, connecting the two. > > > > Swarf protection for the bare x screw is in the form of a 1/8" plate > > of rack panel alu let into the top of the long carriage and glued > > in, and a similar but much shorter piece of 24 gauge sealing up the > > bottom of the saddle between the ways, and the rear of the saddle > > that used to carry 60 lbs of taper attachment stuff, will be walled > > off to prevent swarf ingress from air hose cleanup activities. All > > that work on the rear of the saddle is in the future yet of course, > > as is fitting and shimming a full length brass front gib, wide > > enough to ride the unworn underside of the bed once I get as much of > > the paint washed off as I can using enough acetone I might get > > raided to find the meth lab. :( None here. > > > > That pair of steel postage stamp sized plates that served that > > function are badly worn and so is the under edge of the bed for the > > first quarter inch they rubbed on. If the brass wasn't such a pita > > to make, I'd consider makeing a tapered gib. > > > > I have a block of cast partially machined to replace the junk > > compound. I am debating with myself about putting 4 holddown bolts > > in the base, but would have to make the other 2 bolts. Belt and > > suspenders approach to getting a truly rigid mounting point for that > > big Phase-II QC tool post. > > > > Thats another thing I did to TLM, a solid block of cast to replace > > its flexible compound, and with the tapered gibs, precision is now > > limited by the 2 ball screws moving it. And thats nice!! But the > > screw is wearing out its nut from swarf sneaking past the felt > > seals, so z backlash was reset a couple weeks ago to 0.163 mm's.:( > > It's setup to do metric natively, to train me if for no other > > reason. :) > > > > The coffee and morning pills have kicked in about as much as they > > can, so I'd best be up the hill & into the shop building in front of > > TLM making that special hub I need for the x screw's pulley. > > > > Thanks Erik. > > > > Cheers, Gene Heskett > > FWIW, > I have used Tap Magic Aluminum for turning aluminum with great > success. I was turning some Schedule 80 aluminum pipe and it was > galling and the surface finish as really bad. > I have no idea how it works, but it was better than anything else I > had. The improvement in > surface finish as amazing... We were using both carbide and hss > tools. BTW, the stuff also works well for tapping gummy alum alloys. > > Dave > I have been on the lookout for some of that locally, but my hand is still empty. Darnit. I have some Buttercutt thats tolerably good. But its not much use sitting in the garage when I'm up in the shop. Theres a bottle of rapid tap sitting around someplace too.
Thanks Dave. Cheers, Gene Heskett -- "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> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
