On Thursday 18 August 2016 04:58:20 andy pugh wrote: > On 18 August 2016 at 04:37, Gene Heskett <[email protected]> wrote: > > That flat line going to the left > > to zero speed, is the maximum steady torque over a longer period of > > time without overheating something. > > A typical threading operation probably doesn't count as "steady state" > except on very long threads. Most threads are not a lot longer than a > nut when being made as a special.
In that kind of a time frame, I agree. I finished up the compound replacement for the little monster and installed it yesterday. Now, when cutting heavy, I see some movement of the cutting tool downward because that 250 toolholder, on a wedge type steel qc post still isn't solid enough to effect a truely rigid mount. But I cannot detect anything else bending except the spindle itself. Downforce from the cutting can now be adjusted so that it is within the footprint of the saddle even with the offset the QC holder because I put the bolthole off center about 3/4", so I can move the qc about 1.5" just by loosening it to gain access to the holdown bolts and turn it. About 10 minutes faster to do now. OTOH, its "first swarf" was a block of cast iron, left over from making the toolpost block for the little monster, and which weighs north of 15 lbs, was mounted by reverseing the jaws in the 5" 4 jaw. But because it was a casting sprue cutoff, had some lumps that needed turned away before it will clear the top of the crossfeed. At about 250 rpm, cutting about 1/3rd of a millimeter per pass, I think the next adjustment is tool height as that block is around 1/8" higher than the compound assembly it replaced. One side effect of removing the compound, whose base has demolished the X screws swarf cover several times, is that with just the round riser, I have gained at least 1.5" of inward crossfeed motion, and that is going to be a huge help. And the slight concavity of both top and bottom faces has made the rotational setting of the toolpost much more secure. I have lost my gcode to workface reference because the whole toolpost turned on the compound despite the bolt being tight enough that I once pulled the threads out of the compound and had to buy and install a new one. I drilled and tapped this block a thread or two deeper, but was not able ot get a grip on the shank of the bolt to extend the threads on it. They end at about 3.5 turns with a sharp shoulder because that is as thick as the top slider of the compound. IMNSHO, 3 to 3.5 threads of engagement is not enough in cast iron. So I may see if I have an r8 that can grab it on the threads, put a thread cutting tool in the vice, and make a G76 work on the mill to extend them another 2 or 3 turns now that there is enough iron in the block of cast to do it. That will be a bunch of air cutting to get the threads in synch. Wish me good luck on that. 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
