On Sunday 28 January 2018 02:36:52 Marcus Bowman wrote: > On 28 Jan 2018, at 07:00, Gene Heskett wrote: > > On Saturday 27 January 2018 22:03:33 Eric Keller wrote: > >> Bison maybe? Currently considered to be pretty good, and priced > >> accordingly. > > > > So I've noted already. > > > > All the Bisons I see today have a brass logo button inlaid in the > > face. That does not exist and no place it was exists on this one. > > I have a TOS 4 jaw self-centring chuck for my mill (lives on a plate, > and faces upwards, for use holding cylindrical stock facing upwards. > That's Polish, but, like the Bison, has a round recessed glued-in > badge. The quality is ok. Interestingly. my impression is that there > arefewer Polish chucks for sale at the moment, because the centre of > low cost production seems now to be India. Don't let me get started on > 'quality'. I have a Burnerd Griptru chuck on my lathe. I bought it new > in 1975, and I would defend the quality and accuracy against all > comers. It's an adjustable device which uses 3 conical adjustment > screws in the body to bear on a loose fitting backplate, and although > it holds its accuracy on everyday tasks, it can be adjusted to within > 0.001mm for any given diameter (let's say half a tenth, in old money). > This supplier has a useful conversion kit for standard chucks up to 5 > inches http://www.hemingwaykits.com/acatalog/Adjustable_Backplate.html > so I suppose you could make a device like that. It's one step up from > adjustment with a machinist's hammer.
That, scaled up to fit a 7" and change looks like a good idea. But this chucks mount bolts are in its outer edge, so the idea might have to be inverted somehow. I'll try the enlarged holes in the plate idea first, and rather than trying to dial the body, chuck up a second alu rod 1.75" in diameter, (I bought 2 of them to make the jig for the ER-40 pieces while they were being ground to correct so I've one 8"er left) and dial that in at the chuck with the deadblow, then paper shim it for run-out 6" out. But that I think is going to require the plate be bored for all 6 bolts just so I've enough choices for places to shim. The thought also comes to mind of straddling the bolt holes with about 4mm or 5mm setscrews whose tips are polished flat, loosening the bolt and pushing with the screws, then re-tighten that bolt. Wash, rinse and repeat for every bolt that needs shimmed. Biggest problem with the lower cost 3 jaw chucks is the small through bore usually under 1.5". Which because this one can pass a 1.5"+ workpiece, makes it desirable to rescue it. Or just give up and dial in the 4 jaw, like I've been doing for the 5" on TLM for years. The Little Monster, is a cnc'd 7x12 with just about every improvement ever done to one of those P.O.S. With such a small saddle foot print, the last fix, tapered gibs, makes a decent small lathe out of it. With a 1 horse motor, it can break drive parts in a heartbeat, so the willow tree branch of a compound had to go. Now it has a block of cast iron that can be rotated for tool tip offsets to keep the cutting forces within the saddles footprint on the bed, that and the tapered gibs has made a whole new lathe out of it. I made a similar but bigger block for the Sheldon on it, same idea, rotate it on the crossfeed and adjust the qc post to keep down force within the almost too narrow crossfeed ways. All bets on tippage go out the window when the die grinder with its heavy inline motor hanging 15" out to the rear is mounted, but its at least repeatable, so its a shrug. The die grinder is about 17" long, but the mount seems plenty rigid enough. It winds up mounting in a std 250 series qc holder. Its a little bigger and heavier than a black & decker #8, but considering its 15% of the cost of the b&d was in the 1950's, has already outlasted 2 or 3 of the #8's. I'm amazed, I must have more than 150 running hours on it, still running like new. I dial the voltage down with a powerstat when I have bigger stones or a 4" diamond disk mounted. A 1" alox stone does a fine job at 75 volts. I ramble on a quiet Sunday morning, as always. Gotta have somebody to talk to, the missus doesn't have the wind to carry on a real conversation any more. And I think best sitting here "talking" about it. But I'd better go see what I'm fixing for breakfast, and get some fresh coffee under construction as it 9:14 locally. Thanks Marcus. > Marcus > > > What I am fighting with has all the earmarks of its being pulled out > > of shape. Bolted to the backing plate, the body is not only > > eccentric, but apparently out of round. Move the dial to the face, > > after refacing the plate, and the thickness, plate to face, is > > around 8 thou out. I can paper shim between it and the plate and > > help it, but is such a wild variation just in turning it 45 degrees, > > 5 thou or so just between jaw channels, that seems to repeat, per > > face section with some wobble superimposed on that. To get it > > centered, I am going to have to remove the plate, taking it to the > > mill, and enlarge the bolt holes by 15 thou just so I can take a > > deadblow and center it, sorta, on the OD. The bolts are a very close > > fit. The are places for 6 in the back of the chuck, but only holes > > for 3 in the backplate. > > > > I keep coming back to two things, 1. the scroll is very lub > > sensitive, its its swimming in vactra, it takes a hand on each end > > of the key to adjust it, from any pinion. 2. Even with 10 thou or > > more off the OD of the register, the bolts won't let it move far > > enough to get the body concentric, maybe 6 or 7 thou total until I > > enlarge the holes. > > > > When I wanted a 4 jaw indy, I went for a $89 plate, and the $114 8". > > > > I have it dialed in pretty good, its within .001 of round, and once > > the plate was faced, within .001 axially. > > > > But this one is so far out of round I hardly know where to start. So > > I'll start by switching stones in the grinder, and just barely kiss > > the plate, maybe taking another 2 thou off, and see if I can bolt > > the plate down on the mill, use my hole locator code to find the > > holes in the chuck, and make all 6 holes in the plate new and 15-20 > > thou bigger but based on the chuck, not the existing holes in it. If > > that won't let me true it up, I guess I'll throw real money at it. > > > >> On Sat, Jan 27, 2018 at 10:01 PM, Gene Heskett > >> <ghesk...@shentel.net> > > > > wrote: > >>> Greetings; > >>> > >>> I can't quite identify it. It has a weakly acid etched label on a > >>> face but its well worn, and I can only read "made in Poland" for > >>> certainty. > >>> > >>> Its a 3 jaw, scroll, 2 piece jaws, and about 7", maybe 7.25", in > >>> diameter. Looks and feels nice & snug yet, but true it isn't even > >>> with a refaced backing plate. > >>> > >>> Someone here once named it, but I can't seem to find it in my list > >>> corpus here & now. > >>> > >>> I am trying to make it run true, despite a slightly bent spindle, > >>> by refacing the backing plate, and find I am essentially spinning > >>> my wheels. > >>> > >>> So I am debating replaceing it as this backing plate is a bit thin > >>> for my first complaint. > >>> > >>> But I need to know if these Polish made chucks are good to start > >>> with. > >>> > >>> So please tell me what you know about this one from no more than > >>> I've supplied above. > >>> -- 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> ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
