An Electronic Lead Screw controller using a Teensy 4.1

My prop spacer for the X-scale came out ok. It was slightly undersized, but only by a 1/2 mm (over 286mm) so I call that a victory. It fit pretty well, the PETG piece was screwed to the mounted cross slide (2 M3 screws) and confirmed the basic operation was ok, the travel made sense and the offset was sensible. The piece itself isn't very stiff, I printed it with 3 perimeters, in draft mode, and only 20% infill, but it is serving it's purpose.

I installed the uncut glass scale on one end of the PETG piece, with an M4 screw, and made sure everything was below the cross slide, and then marked the other end of the scale for cutting. I think I will leave one end of the aluminum a mm or two longer, in case the cutting of the scale goes awry with total length.

You don't have any pictures right now, because 1) I forgot to bring my phone down to the shop, and 2) black PETG prints are tough to photograph well. Should have printed it in red...

What's next? Need to cut the aluminum to the basic shape, 3/8" x 23.25mm x 290mm for now. I don't see a need to change the 3/8" dimension, it's good enough. Then machine it.

Then I need to figure out how to clamp the scale and cut it. I'll try the mill first to see if it fits. Otherwise I will have to use cruder ways.

If I'm too intimidated by the scale cutting, then I'll work on extending the back splash. Have to do that anyways. Then back to the scale trimming.

Still need to make a spacer for the read head. Think I may mill the lower half of the cross slide flat. Right now there's an annoying 4 degree (or so) angle to it. Once the lower cross slide is in the mill, then I can also drill and tap the mounting holes.
 
Here's a picture of the printed piece mounted on the cross slide. It turns out that I only have to push the backsplash about 8mm to clear. I thought it would be a lot worse than that. I will look into spot welding on tab extensions near the headstock and a simple spacer by the tail stock end. Although the picture doesn't look like it, I could go back another 20-30mm without issues.
PXL_20230318_004938132.jpg
 
Here's the same thing in aluminum now. It's a little long by 5mm, (towards the operator,) I will trim it and drill the last mounting hole after cutting the scale.
PXL_20230320_175700058.jpgPXL_20230320_180313061.jpg
I modified the pockets, by using a radiused 1/2" end mill, and fully making a channel. The counter bore was breaking through, and I didn't want any sharp edges. While making this, I was reminded that I need to make some machinist jacks. The end pockets have chatter in them, since they were unsupported. Yet another thing to make in the shop. I'll do that when I get the lathe together!

Next thing is to cut the scale. Have to find some tissue (or something like that) to stuff inside the scale to help prevent the glass from buffeting around and keeping the rest of the scale clean. Looks like the only thing I have to cut this is a power hacksaw or my 4x6 band saw. Think the band saw may be a better choice. That will be fun - have to remove the 6TPI blade (was cutting 1" plate) and find something much finer. I never have fun replacing the blade, it always has a mind of its own!
 
I think I would fill the space with modeling clay. Should support it really well and dampen vibration. Just have to make sure not to fill it too far back. something water soluble like plaster would work too.
 
mattthemuppet2 said:
angle grinder with a thin cut disk works well too
Click to expand...
With a steady hand, I'd imagine so. My pen name is apt for angle grinders, can't seem to hold them still or terribly straight. Still think I might be better off with the band saw.
 
MikeWi said:
I think I would fill the space with modeling clay. Should support it really well and dampen vibration. Just have to make sure not to fill it too far back. something water soluble like plaster would work too.
Click to expand...
Got some modeling clay at Target tonight. Get to try this out in a day or two. Will probably do some lens tissue as well, just to block the clay.
 
While waiting for some lint free tissue, was pondering how to accomplish threading to a stop. Think I have most of it figured out. Wrote up the steps in my notebook and need to review it. Also wrote up feed to a stop.

What I am still thinking about is the user interface. I can implement a soft keypad, if I need to. (It's not that much fun for me, but I'll do it.) I can also simply record the start and stop Z position (because I integrated the DRO's) or the lead screw step count. Basically it comes down to, what is an intuitive and minimal set of operations that are sufficient to do threading. Feeding to a stop is considerably easier. While I am at it, I will add in multi-start threads. I believe that can be accomplished by simply indexing the start spindle angle for successive starts (at the same Z position). (And of course by increasing the pitch by the number of starts.)

I'd like to initiate the operation by first selecting a thread. Once this is done, I can enter a special menu which enables these feed/thread to a stop modes. There are place card holders in my code already.

Still thinking about the nature of the interaction with the operator. I want to minimize some of the human operations, but not all yet. This boils down to what is the ideal (or reasonable) level of human interaction. Remember, I really don't want a full CNC operation, but I do want it to be easier to get some things done.

Yeah, I'm babbling, perhaps thinking out loud is a better term for it.
 
While doing multi-start threads you could also implement an offset for the start like here:

He's doing a Z offset of half the depth of cut so that you don't have to mess with the compound angle and accommodate folks that have replaced the compound with a solid block.

I have some thoughts on the workflow but haven't sent them to you yet. Hopefully i'll have a few minutes tonight to send you something.
 
WobblyHand said:
While waiting for some lint free tissue, was pondering how to accomplish threading to a stop. Think I have most of it figured out. Wrote up the steps in my notebook and need to review it. Also wrote up feed to a stop.

What I am still thinking about is the user interface. I can implement a soft keypad, if I need to. (It's not that much fun for me, but I'll do it.) I can also simply record the start and stop Z position (because I integrated the DRO's) or the lead screw step count. Basically it comes down to, what is an intuitive and minimal set of operations that are sufficient to do threading. Feeding to a stop is considerably easier. While I am at it, I will add in multi-start threads. I believe that can be accomplished by simply indexing the start spindle angle for successive starts (at the same Z position). (And of course by increasing the pitch by the number of starts.)

I'd like to initiate the operation by first selecting a thread. Once this is done, I can enter a special menu which enables these feed/thread to a stop modes. There are place card holders in my code already.

Still thinking about the nature of the interaction with the operator. I want to minimize some of the human operations, but not all yet. This boils down to what is the ideal (or reasonable) level of human interaction. Remember, I really don't want a full CNC operation, but I do want it to be easier to get some things done.

Yeah, I'm babbling, perhaps thinking out loud is a better term for it.
Click to expand...

With a DRO you may as well implement your software to incorporate a DRO input start position as reference for all operations, and have your els software allow inputs for start and stop points as part of the basic operations. That then allows feeding toa stop, threading to a stop, and any other operations that require reference points, such as multi-start threading, tapers etc. That is going to be my methodology.

I was thinking of simple button push to reset reference point, so I can make changes via the DRO for various tool offsets when I switch holders and such. I think this is best way to allow to flip between controls. It should be easy enough for the els software to adjust the start and stop points when you reset the DRO reference reading. I hope that makes sense to you
 
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