Messages

771

General Mach Discussion / Re: Spindle encoder for cnc lathe conversion?

« on: December 17, 2009, 10:57:19 PM »

A piece of black tape across the pulley is all you need. It works great. I just got mine up and running this week. It is not without its problems setting up if it is your first time (it was my first). It really will depend on your understanding of mach and its settings. You can do it. Everyone here will help you.

772

General Mach Discussion / Re: Use Spindle Feedback in Syn Modes ? Experiences

« on: December 16, 2009, 12:34:06 PM »

Rich and Hood thank you for helping in my understanding of this topic. I have truly enjoyed the thread. I was very aware that I would try to learn as much as I could on a machine that wasnt so destructive to itself before going bigger. I also could have bought a plug and play system but what would I have learned? This is fun, challenges the brain and isnt filled with groupies like GOLF. Rich I definitely wouldnt even want to tackle such a technical topic, nor could I. If I ever do have a suggestion that I think would help, I will definitely throw it out there. So far your doing great.  "I must verify the results for myself. Somebody elses testing procedure could have been different or flawed." this comment was a statement on my stubborness/ignorance at others peoples experiences applying to my life. Been a problem since birth, I am 48 now and just beginning to realize it! I guess that might be better than never realizing it. Does age make you give in and conform? or make you realize you werent as smart as you think you were?

773

General Mach Discussion / Re: Use Spindle Feedback in Syn Modes ? Experiences

« on: December 16, 2009, 11:31:18 AM »

Rich, I always just thought averaging was used only for the display in Mach so that you dont see that jumping about if you have variations such as you may get with a vee belt that is unevenly worn but maybe not.
Hood

Interesting, so maybe averaging helps quell the erratic rpms I see occasionally? Btw the first pass segmenting I was referring to even occurs with an air cut. I sometimes turn off my controller to reset my tool by manually turning the stepper when it is off (could be the problem why I have issues at startup LOL). I have read there are ways to reset the code or tool offset instead of the way I am doing it. I just havent learned them yet. Btw did I tell you how much abuse a little Sherline can take waiting for an idiot to hit the Estop? What an excellent learning tool.  

774

General Mach Discussion / Re: Use Spindle Feedback in Syn Modes ? Experiences

« on: December 16, 2009, 10:51:45 AM »

That is what I would have though too regarding the initial pass. I am not sure if it actually slows because the toolpath on the rod is very symetrical. It just seems to sound that way. Since there are so many variables in my set up, loose gibs and screws I will spend an hour or so adjusting before my next real passes. Also I will check all of my settings and possibly record it. I have been thinking about another youtube account for these videos. I know how much I enjoy other videos when I need to see new set ups or ideas. Of course mine would be more the crash and burn type but maybe someone could learn from my mistakes! I learn better by making my own mistakes, seems like I must verify the results for myself. Somebody elses testing procedure could have been different or flawed. Btw I start the thread .1 away from the piece. I do notice in the turn mode my accel is different and I really havent had the time to sort those issues out yet. I have played with the PID settings in an attempt to change it. In my mill profile the accel on the spindle is quick but not on the lathe. Much more of an incremental accel, same motor just different profiles so I am guessing it is a settings change. I dont get much over run either direction regarding rpms. Seems to stay within 3-4 rpms while cutting and 1-2 if no load.  

775

General Mach Discussion / Re: Use Spindle Feedback in Syn Modes ? Experiences

« on: December 16, 2009, 09:12:43 AM »

Hood, 2 more questions. What is a pullstud for? (I am guessing it is for a drawbar). Second now that I see your toolchanger, I have a new idea for my rotary table that is sitting on the mill table LOL. On my little lathe that could probably work as well as anything else I have seen. Just a round plate to bolt to the table with slots cut or broached with set screws. Too easy. Well I say easy but the rotary table (Sherline too) is bigger than the entire lathe table but I am going to look. It might be a good idea for my next lathe.

776

General Mach Discussion / Re: Use Spindle Feedback in Syn Modes ? Experiences

« on: December 16, 2009, 08:57:22 AM »

Hood, great work as usual. When I first start the simple threading wizard, the very first pass does a 3-4 segmented pass. I hear the steppers slow down and speed up. It does this only on the first pass and each pass after that smooths out and speeds up til S value is acheived. Usually 3-4 passes til up at full speed. The threads are very evenly spaced and appear very good. I have no knowledge or tools to verify quality of thread. I do know the nut fit better with less play than the bolt I copied the measurements from. I bought the bolt for .67 cents, I told my wife mine was better so I am going to charge .68 cents and claim it is American made. I do have some surface issues that might be the aluminum (home depot) I am using. I will have to try some different stock.

777

General Mach Discussion / Re: Homann DC04? Threading with pics

« on: December 16, 2009, 08:06:12 AM »

Rich, The Sherline is a great machine for people who want little stuff. I can see the results of some people who are patient and they are incredible. I can also see where I want a bigger more rigid lathe, not a huge lathe just bigger. But it is a great learning tool. I did read somewhere last night that the aluminum rod (Home Depot stock) was a gummy metal that doesnt machine well. So I will have to get some 6061 and some 12L14 because I hear as a steel it works very smoothly. I really get alot of my metals from a recycler near my house. With that identification becomes an issue. THANKS ART for your work on this and all you do.

778

General Mach Discussion / Re: Use Spindle Feedback in Syn Modes ? Experiences

« on: December 16, 2009, 07:58:50 AM »

I agree in theory. I was shocked at the results and as usual it was an accident. I was merely changing settings trying to figure out why speeds didnt match indicated speeds and proceeded before correcting the setting. That is exactly why I posted this. I might try to replicate it but damage usually occurs when I do things on purpose. So for correct threading I can see where spindle feedback would be a necessity however is speed averaging also to be checked? Seems like averaging would defeat the compensation that the feedback was provided for. What is up with the first pass? It starts in segments and then smooths out over the next few passes. Very interesting to hear and watch and to see a decent thread being cut. I am hypnotized watching it perform. The mathematical idea that you could match linear and rotational travel to a single point at 400-500 rpm is incredible.

779

General Mach Discussion / Use Spindle Feedback in Syn Modes ? Experiences

« on: December 15, 2009, 10:07:28 PM »

Anybody understand this? The wording seems like it would be obvious but is it? I swear I have run threads both with and without it checked with similar if not better results without it checked. If it is checked, I uncheck spindle speed averaging as they would seem to conflict in the threading scheme, again I could have some flawed understanding of what is necessary. And today in a lapse where I had been using the manual speed control, I forgot to switch it back to automatic speed control on my spindle, hit cycle start and somehow the tool still hit the right place on each return pass at least 5 times before I realized my error. You know if I had a list of all the things to reset, change, plug back in, I couldnt see the machine. 

780

General Mach Discussion / Re: Help with Spindle Index please

« on: December 15, 2009, 09:53:03 PM »

Having just been there this week, if you have not set one of these up before be ready for a challenge. Once up and running it is incredible but before that I wanted to kill everything. As mentioned above the low index debounce setting is important (0-1) if you can get away with it. The index led on the diagnostics doesnt really keep up (it bothered me too) if the motor is on but if you manually turn the spindle the opto sensor "sees" the leading edge very accurately and does it at speed too. I also get a random rpm displayed very quickly with erratic changes especially at low rpm the motor speed doesnt actually change just the display. It doesnt seem to effect anything and the numbers it displays are huge like 48924 rpm but synchronization is spot on.