Thank you for posting that. So in the places where I'd make a pattern and cast from scrap aluminium you 3D print the part. Very nicely done! John
> -----Original Message----- > From: Chris Albertson [mailto:albertson.ch...@gmail.com] > Sent: June-14-21 7:44 PM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Spindle Control > > On Mon, Jun 14, 2021 at 9:43 AM John Dammeyer <jo...@autoartisans.com> > wrote: > > > Have you any photos of the 3D printed motor mounts etc? Direct drive or > > belt driven? The 3Nm implies size 23 so I'll guess direct drive. > > John > > > > THis shows X and Y. https://youtu.be/wupYP2NNsXI?t=33 > > This shows the Z axis. On this machine the nut spins on a non-rotating > ball scew https://youtu.be/tlMTksuOuZQ?t=27 > This is a render of some z-axis parts https://a360.co/3zrzIwB > > Note that in the two above videos I am used 3D printed timing belts. At > first I did this as a joke but they actally work for almost an hour with is > long enough for testing to see if you have the right size belt. It is > just plane old PLA printed 100% solid. All the timing pulleys are printed > but have steel hubs and steel set screws. > > Here is an interactive 3D model you can look at. This versionhas some > alignment issues but by using the "eplode" button and slider you can look > at the parts and rotate them to see all sides https://a360.co/2TxOscU > > "Universal PWM spindle speed control device" (don't laugh, it works.) > https://a360.co/2N95AiL > > > > > > > > -----Original Message----- > > > From: Chris Albertson [mailto:albertson.ch...@gmail.com] > > > Sent: June-14-21 8:41 AM > > > To: Enhanced Machine Controller (EMC) > > > Subject: Re: [Emc-users] Spindle Control > > > > > > Yes, I thought about reverse engineering the spindle motor controller and > > > fitting it with a conector for external PWM input but my goal with this > > CNC > > > conversion was to try and do the lowest cost and easiest possible > > > conversion and document it. So at every decision point I take the > > simplest > > > route that costs the least and most importantly, they anyone reading my > > > instructions could follow. As soon as I suggest modifying a controller > > > board, I've lost 90% of the machinists who might be following my > > > instructions. > > > > > > To that end I've 3D printed almost all the parts needed for CNC > > conversion. > > > People usually use metal but the stepper motors I use only only > > produce > > > less them 3 Newton meters of torque. The the maxim force the motor > > mounts > > > will ever see is 3 Newton meters. I don't need cast iron for that, > > plastic > > > works. My goal is to do the complete conversion including motors and a > > > ball screw all for under $400 with an assembly time of no more then one > > day > > > of work, not counting the time needed to print the parts. I looks like > > > I'll meet these goals. > > > > > > I use a dial indictor to measure deflection under load of the plastic > > parts > > > and there is one part on they-axis that needs to be redesigned into the > > > more organic-looking shape with compound curves. I find this is the > > > "secret" for making strong 3D printed parts, It is the same reason car > > > fenders don't bend, even though that are made with thin sheet metal, It > > is > > > the compound shape. Printed parts are like that, they are made of a > > thinn > > > skin of solid plastic over a light foam-like core and all the strength is > > > in the skin. Flat slabs of printed plastic are not very strong or > > ridgid. > > > > > > I does not impress me much that someone can build a CNC milling machine > > for > > > $10,000 and 6 months of work. Anyone can do that. What I want is "under > > > $400 and one day". After about three attemps I'm getting closer to > > that. > > > When I get there I'll write it up on the web and publish the design > > files. > > > > > > So, back to my spindle speed controller. This device will literally > > > replace the knob on the pot and cost about $6 to make. > > > > > > > > > > > > On Sun, Jun 13, 2021 at 11:09 PM Gregg Eshelman via Emc-users < > > > emc-users@lists.sourceforge.net> wrote: > > > > > > > How old is that mill? Those Chinese mini mills and lathes have had PWM > > > > spindle motor controllers for many years. I used to have a Grizzly mini > > > > lathe with a low 3 digit serial number, probably from the first batch > > they > > > > imported. I was at least the 3rd owner and I had to fix a lot of > > issues, > > > > both original and from prior owner abuse. One fix was resoldering one > > end > > > > of a big resistor on the primitive and very noisy motor controller. > > > > You can buy a new PWM motor controller and potentiometer to upgrade. > > > > > > http://benchtopmachineshop.blogspot.com/2017/01/mill-speed-controller.html > > > > On Sunday, June 13, 2021, 2:30:15 PM MDT, Chris Albertson < > > > > albertson.ch...@gmail.com> wrote: > > > > I have a Harbor freight mini mill with the dumbest possible spindle > > > > control. The mill comes from the factory with a variable resistor to > > > > control speed. My idea was to connect a variable resistor to a $5 > > model > > > > airplane servo. So the PWM output from LinuxCNC drives the servo and > > the > > > > servo turns the pot which controls the spindle motor. I would never be > > > > able to do rigid tapping with this setup. > > > > _______________________________________________ > > > > Emc-users mailing list > > > > Emc-users@lists.sourceforge.net > > > > https://lists.sourceforge.net/lists/listinfo/emc-users > > > > > > > > > > > > > -- > > > > > > Chris Albertson > > > Redondo Beach, California > > > > > > _______________________________________________ > > > 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 > > > > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > 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
