On Friday 02 May 2014 22:47:13 andy pugh did opine: > On 3 May 2014 01:43, Gene Heskett <ghesk...@wdtv.com> wrote: > >> (Turning with CBN tips is closest to single-point grinding, if the > >> material isn't red hot and fizzing, you need more spindle speed). > > > > Much of my tooling is indexable carbide inserts, so I'm fairly > > familiar with red hot swarf, and they do cut better at the higher > > temps, but that does not sound like CBN. Define? > > Cubic Boron Nitride, it tends to come as an insert in the insert: > http://www.ebay.com/itm/371055717060 for example has one darker tip. > > I doubt you have seen red hot swarf quite like this: > https://www.youtube.com/watch?v=BU14tfjUfQU > > Interestingly this video shows the same problem I have had, you need > to have more back-out than normal or the tool drags on the return. > Unless you have a very stiff machine then there will be more flex than > normal, but that doesn't mean you can't hit size. > > The last screw I cut was on the Colchester Student at the Motor Club, > and it was a revelation. > > > Also, these screws do not have countersinks in the ends, so I can't > > put it between centers so I can hog it and stay at dimension. > > You can probably add one, the middles are normally quite soft.
No, I don't have any inserts like that. But the ones I do have are about the same price, north of $140 for a 10 pack. As for a support center dimple, I can usually make those if I can get my tailstock well enough aligned as I do have some cheap center drills. The tail stock adjusting facilities of a 7x12's tail stock aren't conducive to maintaining its alignment, and some of the error is vertical, it rises as I run the barrel out, which has no way to adjust at all short of scraping its base or the X sliders bottom. Genuine POS... I am probably accuracy ahead to just carefully set the 4 jaw, and expect to have to write a bit of X taper to compensate for headstock miss-alignment. Too bad screw comp is one dimensional, lengthwise. :( That might be best handled as an L10L2P1 R(+-)0.005?, or whatever R neutralizes it. Once established, I could put that in the default startup of the .ini. And doing 80 or 90 mm of the end of this screw would sure serve as a calibration run. I used a dremel with its bigger flat diamond wheel for something like this in the past, so with the dremel on slow & screwed enough to clear the center mount, slow so the diamond doesn't get too hot, and the spindle idling at 200 rpm or less, it might take 2 or 3 days but once I get it running straight, I can turn out the lights & get some sleep. Humm, mount my .0001" dial indicator on the tool post, put a pad on the end to straddle the grooves, and running the carriage back and forth should give me a ball park error for setting the R. Worth a try anyway. Because the carriage isn't front weighted enough (the x motor is on the rear), it does tend to turn about a thou as it rises off the v-way to bring the front gib in solid restraining contact, and that is best handled with a back out move before the retrace move. Adjusting those gibs is a genuine chore as the only way to access the adjustments is to drop the apron coupling and run the apron and nut out of the way. Even then, getting the tools in there to do it is a PITA. Wish I had a decent lathe in the first place. Sigh... 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 ------------------------------------------------------------------------------ "Accelerate Dev Cycles with Automated Cross-Browser Testing - For FREE Instantly run your Selenium tests across 300+ browser/OS combos. Get unparalleled scalability from the best Selenium testing platform available. Simple to use. Nothing to install. Get started now for free." http://p.sf.net/sfu/SauceLabs _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
