On Thursday 18 April 2019 20:02:45 Ken Strauss wrote: > Weldon shank is round with a flat on the side. A setscrew prevents > pullout. > > I haven't done personal measurements but I've often read that Weldon > shank is worse than ER collets for low TIR when using small diameter > tools which are usual in a high speed spindle. > In that case the TIR can't help but be worse as the setscrew will force it to the far side of any clearance. So TIR's in the .002" range are not impossible. In the case of an engraving v bit, the flat should be located such that this offset presents the cutting edge to the work as opposed to the heel, which likely will just burn the tool and the workpiece. We should be so lucky as to reliably get that timeing from the tool venders. While etching circuit boards, I've been known to stop if the cut is leaving a big burr, and rotate the tool a quarter turn in the ER and try again. Usually I have been able to get a cleaner cut.
A dead flat pallet, and a cut that does not dig into the glass makes a huge diff in the life of the tool, That dead flat bottom to the board pallet is one of the reasons I drill maybe 65% of the way thru the board and turn it over so the drill pattern does the same thing, with the holes meeting inside the thickness of the board, The drill never comes thru to damage the bottom of the pallet, but the etched side of the board does need to be scrubbed with $0000 steel wool so there are no burrs sticking up to warp the board. I drill and tap 0-80 flat headed screws to force the board to a consistent location since the pallets pocket is usually a couple thou oversized. Stiction in the z axis movement can be a board and bit killer if the Z ways aren't relubed and exercised to spread it before starting each side of the board. I've no clue if this 6040, running Z on rods, will be better or worse than the old HF I used to do that sort of work on. The G0704 isn't noticeably better for movements that small. And of course thats as yet untested on this 6040. Stiction was a huge problem on the old small HF, which is why it had extra 1/2" alu plates on each side of the sled, carrying 2 ball bearings that rode the face of the post, effectively extending its "wheelbase" from 2.5" to around 6". Gibs set just tight enough to make sure all 4 bearings were hard to turn against the post. Wipe the dirt off the post, put a fresh squirt of vactra in the top of the gibs and the stiction disappeared for hours. It will be interesting to see how this 6040 handles that when it gets its first pcb job. It did not come with lube instructions, just 40 pages of mach3 setup propaganda, and a demo copy of mach3 on a teeny cd. I'll never run it, no windows allowed on the property. Thanks Ken, & take care. [...] 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
