On 9/23/2016 6:57 PM, Gene Heskett wrote: > 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
I have used the standard Tap Magic and Rapid Tap and the Tap Magic Aluminum is totally unlike the other cutting fluids. Tap Magic Aluminum is very thin stuff. I applied it with a paint brush. From the viscosity you would think that it would do nothing but it really worked well. Dave ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
