I knew I'd need more spindle torque for tapping. That's why I made a two step pulley for the spindle and the 1800W servo.
One tiny little problem. http://www.autoartisans.com/mill/SpindlePulleyRawCasting.jpg In thinking through the process to be able to pull the pattern from the sand the larger pulley is in the wrong place. The cone drive to the spindle is largest at the bottom and the taper ends up putting the smallest pulley at the bottom. Which is why the encoder wheel was large enough to clear it but not really large enough that I had room to move the belt without removing the encoders. Another mistake was the length of the keyed arbour for the tapered pulley holder. http://www.autoartisans.com/mill/Arbour-2.jpg Way too long. Lots of vibration when I was cutting the pulley. http://www.autoartisans.com/mill/SpindlePulleyBuild-1.jpg http://www.autoartisans.com/mill/SpindlePulleyBuild-2.jpg And when I bored out the motor pulley I was oversize just enough that the pulley isn't a tight fit on the shaft. I think it wobbles a tad. So I could either rebuild and make a proper 2:1 reduction for the heavier cutting operations. Or do like I always wanted and finish some of the other projects so I can make toothed pulleys for perfect 1:1 and 2:1. John > -----Original Message----- > From: ken.stra...@gmail.com [mailto:ken.stra...@gmail.com] > Sent: July-10-21 5:56 PM > To: 'Enhanced Machine Controller (EMC)' > Subject: Re: [Emc-users] Runaway PID spindle. > > I've never used any form taps from KBC but R&N is a known brand. You'd think > that a tap without flutes would be cheaper! > > Remember to drill the hole oversize. For example, > https://www.natool.com/wp-content/uploads/2019/06/tapdrillsizes-inmet_web_ca > tp113-116.pdf) suggests a #1 rather than #7 drill for a 1/4-20 tap. You'll > also need more spindle torque than with a cutting tap. > > -----Original Message----- > From: John Dammeyer <jo...@autoartisans.com> > Sent: July 10, 2021 8:07 PM > To: 'Enhanced Machine Controller (EMC)' <emc-users@lists.sourceforge.net> > Subject: Re: [Emc-users] Runaway PID spindle. > > Looks like KBCTools has a few at reasonable prices > https://www.kbctools.ca/products/search/?Keyword=thread%20forming%20tap > > Inexpensive KBC brand > https://www.kbctools.ca/itemdetail/1-363A-0326 > > > They also have a brand name at quite a bit more. > https://www.kbctools.ca/itemdetail/16B-1420-03B > > > John > > > -----Original Message----- > > From: ken.stra...@gmail.com [mailto:ken.stra...@gmail.com] > > Sent: July-10-21 4:46 PM > > To: 'Enhanced Machine Controller (EMC)' > > Subject: Re: [Emc-users] Runaway PID spindle. > > > > The one in the picture came from Fastenal. When they discontinued > > selling them and had them on clearance I purchased their inventory of > > 8-32 and 4-40 taps. I scored a good supply of Balax > (https://www.balax.com/) 2-56 taps from a local flea market. I don't think > the seller understood taps without flutes! > > > > -----Original Message----- > > From: John Dammeyer <jo...@autoartisans.com> > > Sent: July 10, 2021 6:07 PM > > To: 'Enhanced Machine Controller (EMC)' > > <emc-users@lists.sourceforge.net> > > Subject: Re: [Emc-users] Runaway PID spindle. > > > > Where did you get your forming taps? > > > > I just ran my 10-32 into a casting remnant. I keep the risers and turn > them round for bar stock. In this case a solid coupler. > > Clamp in vise, used LED touch sensor to determine center point between > > vise jaws and edge of piece. Move over 1/2" , spot, drill and then use > LCNC to power tap. > > > > Why is this one different from the last exmaple? Because I loaded the > > 'B' version of the BIT file into the 7i92 and changed the HAL file so > > it wouldn't complain that DB25-5 was not available as an output (now > stepgen5 DIR) instead of an output connected to DIR for PWM. Change the Pn > parameter in the servo to use step/dir instead of 0-10V,IN3 for velocity and > direction. > > > > The odd thing compared to my test bench setup was that I had to change > > the sign of the STEP_SCALE to negative to make the spindle motor turn > clockwise. > > > > I then asked it to turn 400 RPM and looked at what the encoder reported > for the spindle. Divide the encoder RPM into 400 and > > multiply the STEP_SCALE by that to set up the pulley ratio since they > aren't quite the same diameter. Now RPM is really close and > > tapping starts immediately. No PID needed. > > > > Freakin awesome! > > John > > > > > > > > > -----Original Message----- > > > From: ken.stra...@gmail.com [mailto:ken.stra...@gmail.com] > > > Sent: July-10-21 2:35 PM > > > To: 'Enhanced Machine Controller (EMC)' > > > Subject: Re: [Emc-users] Runaway PID spindle. > > > > > > I haven't been following this thread too closely but why not use > > > thread forming taps? They work great in ductile materials such as > > > aluminum and there is no problem with chip clearing since there are > > > no chips. Just be sure that you drill the right size hole according > > > to the tap manufacturer's material (somewhat larger hole than for a > normal tap). > > > > > > On the idea that without a picture it didn't happen, see > > > https://www.youtube.com/watch?v=_DmvkC3tOQw > > > > > > -----Original Message----- > > > From: John Dammeyer <jo...@autoartisans.com> > > > Sent: July 10, 2021 3:08 PM > > > To: 'Enhanced Machine Controller (EMC)' > > > <emc-users@lists.sourceforge.net> > > > Subject: Re: [Emc-users] Runaway PID spindle. > > > > > > Thanks. > > > I've got some really cheap metric ones coming from amazon. Just for > > > aluminium castings and to play with. > > > John > > > > > > > -----Original Message----- > > > > From: Dave Cole [mailto:linuxcncro...@gmail.com] > > > > Sent: July-10-21 10:39 AM > > > > To: emc-users@lists.sourceforge.net > > > > Subject: Re: [Emc-users] Runaway PID spindle. > > > > > > > > I think that is a spiral point tap. > > > > The flute is straight along the length of the tap then the flute > > > > is is ground deeper toward the backside of the cutting edge. > > > > > > > > AutomationDirect.com sells some really nice taps for reasonable > amounts. > > > > > > > > Dave > > > > > > > > > > > > On 7/9/2021 8:32 PM, John Dammeyer wrote: > > > > > The saying we have on another group is if there aren't pictures > > > > > it didn't happen. I hand held the camera so depth of field is > > > > > out a > > > > little on the 10-32 screw head and the macro lens is bad for depth > > > > of > > > field as it is. > > > > > > > > > > Short G-Code 200 RPM tapping into really soft aluminium trimmed > > > > > off an old box or something. Not sure if this classifies as a > > > > > spiral > > > > tip tap but even a forming tap would have pushing this soft metal > around. > > > > > > > > > > http://www.autoartisans.com/mill/SpindleControl/Tapping10-32.jpg > > > > > > > > > > John Dammeyer > > > > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > 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 > > > > > > > > > > > > _______________________________________________ > > > 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 > > > > > > > > _______________________________________________ > > 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 > > > > _______________________________________________ > 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
