Tuesday, October 16, 2018

Shop Improvements In the Works

The battery adventure was a diversion from the real work going on for the next project.  I have some improvements in mind.   In what I see as the order to do them, they are:
  • Build a new front onto my enclosure replacing the bifold doors, and more importantly, allowing me to get to the machine's table without scraping the top of my head on the aluminum rail
  • Resurrect the ability for my CNC Lathe to cut threads.  
  • Look at improvements to the spindle on my big mill, the G0704.  This is aimed at a few things:
    • Ability to start, and stop the spindle from the CNC code - this is fundamental in the real world.
    • Ability to set the spindle speed from the CNC code.  The GCode command exists for this and I think most all of the "real" machine shops do it.  
    • Together, these mean a new motor.  I will do this with an eye to roughly doubling the speed of my spindle.  Which will require new bearings for spindle
    • After this, I'm considering being able to tap (thread) holes under CNC control.  This one, frankly, isn't super important to me, but it looks like the I can accomplish that without adding much cost to the motor and controller improvements that do the first two.  
Changing the front of the enclosure has been on my mind for the last several months.  The bi-fold doors are convenient and give good access to the mill's table, but they're only 25" tall.  If I walk up to the enclosure without ducking, the bridge of my nose hits the top rail.  I need at least another 6 or 8" clearance.  (In fairness, I built this to Hoss' plans and Hoss is in a wheelchair.  The relatively low top rail isn't an issue.)  I spent some time looking at other enclosures online and like the idea of doors that can slide out of the way.  I come up with something like this. 

The new front would be framed entirely of 1x2 standard dimensional lumber.  The doors will slide in grooves routed in the top and bottom horizontal pieces, and will be able to slide past the ends, which will allow lots of access to the inside.  When the doors close, the center door will overlap the two side pieces to keep chips and splashes inside.

Moving to threading on the dedicated CNC lathe was something that re-occurred to me during the flame eater build.  I had to thread some small pieces; nothing I threaded was beyond the size capabilities of the Sherline.  When I built the CNC lathe, it was always intended for threading more than anything else, and after some trials and tribulations I was able to get a few test pieces threaded.  Unfortunately, that was 10 years and several garage re-organizations ago; it barely runs.  In fact, today I wanted to check some aspects of how it ran and it wouldn't run properly.  The cross slide (holding the tool) only moved in one direction, away from the chuck.  The motion to advance the tool into the work was fine.  It took a bit of troubleshooting to find out it was simply a connector that needed to be unplugged and replugged.

In the intervening years, the Sherline world has gotten more sophisticated, with high resolution position encoders and people driving their spindles with stepper motors for complete control of position.  I don't want to overcomplicate this, but I also want it to be dependable for little things like that wrist pin yoke I just made that 3 turns of a 32 TPI thread on it. 

The spindle motor almost is lower priority because it works as it is, it could just be better (and I guess all of these improvements are like that).  Another aspect of the spindle motor upgrade is that a lot of guys update the power of the motor on the 704, because the rated 1 HP is a little light.  I don't mind that as much, but from what I see while getting familiar with what's out there, I'll probably end up in the 1-1/2 to 2HP size by the time I'm done.

Why double the speed?  I have a "speeds and feeds" program called G-Wizard; what that gives me is a good starting point for how fast I should spin the cutter (RPMs) and how fast the table should move in Inches Per Minute (IPM).  Virtually every time I cut aluminum, it tells me to set my spindle to as fast as it can go, giving me the warning that the spindle being maxed out is bad for tool life.  I think doubling the spindle speed will allow me to cut at RPMs less than the max. 

I'm still contemplating the next big project, and I'm thinking of a simple internal combustion engine.  I understand they're less fussy than the flame eater.  I naively told Mrs. Graybeard that I'd like to make something like a single cylinder lawnmower engine.  There's a popular "first IC engine" by a guy named Webster who the engine is usually named after. 


  1. It is likely the metal chips will eat the wood lower track on the enclosure in short order. There is a plastic/fiber track available , maybe from outwater plastics ? IIRC it is set up to use two 1/4" thick glass doors. This track is inlaid into a wood frame. Or you could make some track out of UHMW poly.
    Optimum would be an overhead roller system.
    What is the total span you need to open?

    1. The long dimension across the front is 64". I've seen those plastic tracks and have long thought about them. It seemed that it could come closest to a waterproof seal, probably close enough to keep chips from embedding in it.

  2. If those doors are going to slide on their bottom edges, you will quickly grow to hate them. Chips will get embedded and they won't slide well.
    Please consider the shower door hanging rail system. Outer doors on the same track, center door on the other one. Find someone doing a bathroom remodel and grab the whole setup for parts. New wheels are about $2 each. The unframed doors (bare glass) have clamps that the wheels mount on, that hold the glass. Don't try to use glass, of course.

    If you use 3 phase motors on the lathes, you can over-drive them with a VFD for much higher speed.

    1. The bi-fold doors are hanging from a single M3 screw running in the center of the aluminum extrusion. The bottom more or less slides on the lip of the chip tray. One of the annoying little things I've had with the doors is that one of the screws it hangs from kept unscrewing and then the door would flop into the enclosure. Only on one side. I eventually had to Loctite the screw and glue a cap on the extrusion to keep it from coming out.

      Again, with no disrespect to Hoss, the rest of his CNC conversion is well thought out and designed, with dimensioned drawings. The enclosure comes across as more of an afterthought.

      Getting doors from a bathroom remodel is a thought. I haven't seen any signs of that around the neighborhood, but you know how you can see or be around things all the time and not notice until you start looking for them.