On Wednesday 17 April 2019 15:32:09 Ken Strauss wrote: > The cheap load cells often use a HX711 for the amplifier and A/D. > See > https://www.instructables.com/id/How-to-Interface-HX711-Balance-Module >-With- Load-Ce/ if you're using an Arduino. If you want to roll your > own interface code see > https://www.mouser.com/ds/2/813/hx711_english-1022875.pdf > Thanks Ken, that is exactly what I needed. Now all I need to do is round up the bits and pieces.
> > -----Original Message----- > > From: Gene Heskett [mailto:ghesk...@shentel.net] > > Sent: Wednesday, April 17, 2019 10:01 AM > > To: emc-users@lists.sourceforge.net > > Subject: Re: [Emc-users] Something to think about re the hack-a-day > > tool changer > > > > On Wednesday 17 April 2019 07:12:53 andy pugh wrote: > > > On Wed, 17 Apr 2019 at 06:57, Gene Heskett <ghesk...@shentel.net> > > > > wrote: > > > > Some more along the lines of finding out how much force I can > > > > figure on as being available to tighten or loosen the collet > > > > nut. I can get, for under a tenner, 4 ea 50Kg load cells and a > > > > processor board that converts the very low level diffs of a > > > > wheatstone bridge > > > > > > Why not set your torque wrench to the correct torque for your nuts > > > and then see how far down the handle you have to be to trip the > > > wrench? > > > > > > That tells you what radius of action you need to get the right > > > torque. > > > > > > There is no question that your machine can produce the torque, > > > given the classical "sufficiently long lever" > > > > And that is the final question as to whether or not the idea is > > actually practical. It assuredly is not if the xy motors are so weak > > it needs a carousel more then 18" in radius to the circle of sockets > > just to tighten a tool well enough to dig off .010" of an alu chip > > without slippage of tool in the collet. Even that isn't going to be > > practical but it does serve to outline exactly why the 3" radii > > carousels we are seeing in the videos will turn out to be an obvious > > disproof of concept. The videos of it going thru the motions on > > hackaday would certainly have to suffer from the loose tools > > syndrome if actually put to work on a usable thickness of alu stock, > > say .03125" thick. Putting bigger motors on it would be one option, > > but even 470 oz nema 23's, might not be enough, and most certainly > > could/would bend the frame or bearing rods. I have the motors from > > the broken HF I can move, and probably will as that would at least > > double the power, but just haven't found the round tuit yet. Among > > other things they have dampers on them. But I'll have to change the > > A motor again, putting a 435oz on it. I already changed the 90 for a > > 230, so a 435 can't fail to be even better at holding work. That > > would leave the pair of 235's for XY, and would leave the longer Y > > to be moved to Z duties. > > > > The 1600oz nema 34 supplied as Z motor in the kit for a G0704, which > > was a too slow disaster on the G0704, often stalling at 29 ipm, but > > was strong enough to stretch the bolts anchoring the nut carrier to > > the z sled, causing those to need replacement quite early, but now > > moves at 90 ipm with a 940oz motor that has not further damaged > > those replacement bolts, would be a prime example of overkill. > > However I reused that motor as Z drive on the Sheldon, where it has > > no weight to lift, works well at 75 ipm on the Sheldon with the same > > driver I took out of the G0704. I put in the $180 AC powered drive > > to spin that 940oz on the GO704. Dead smooth and 20 db quieter. The > > DM860H drive is a noisy drive, so noisy I had to install miniature > > quarter round on the keyboard shelf edges to keep stuff on it, > > including the keyboard and mouse. The 860 has very very poor step vs > > amps in coils calibration, so there is no nice quiet all steps in > > the microstep mapping regardless of the current setting. The thing > > you notice most is that a /8 setting actually does 7 steps because > > one of them is way too small. > > > > But thats not solving this measurement problem. Since this $7 kit, > > needs an external clock, it seems like that could be done by siggen, > > for a 500 baud baud rate, and a software uart could do the rest. But > > the packet length is unk until I have such a kit in my hot little > > hands. The fleabay adv's don't say. > > > > Thanks Andy. > > > > 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 > > Emc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users 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 Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
