An Electronic Lead Screw controller using a Teensy 4.1

[WobblyHand]

The horizontal location of the hole in the headstock relative to the left edge is 5.00" or .25" to the right of the left side of the headstock foot. On the tailstock drawing, the distance is 2,75" from the left edge or 1.75" to the right of the left side of the tailstock foot.

Thanks for the dimensions. I'll drill out the holes to something like 3/8" for now and maybe make a wide washer if I don't have any. Later I can open it up to 1/2-13.

 

[WobblyHand]

Spent a little time doing some soldering and added in the buffers for the DRO's. Have the buffer board done. Then I added in the previously tested DRO code to the ELS main code. So far, the code isn't broken, which is good. We shall see how good it is when we hook it all up. Need to design the DRO display, but that shouldn't be too difficult.

Made some prints for me to finish up machining the plates. There's some variation to these lathes, so you need to check your numbers before actually cutting metal. In my case, the 2.75" number should be 2.50" for my tail stock casting and the plate size. The headstock plate looks to be 5.00". I will drill out the holes to 29/64". This will allow the existing 7/16" bolts through, and if I need to later, I can tap the hole to 1/2"-20. That feels better to me than using 3/8" bolts. Of course I don't have any 7/16" bolts long enough... I have 3-1/2" long bolts. Now I need 4-1/2" long 7/16" bolts. At least I can reuse the washers and nuts...

Found out that I was running the fly cutter too fast on steel. Toned it down a bit and it seems to cut beautifully. Hopefully the insert life will be improved as well.

 

[WobblyHand]

Finished the steel riser plates. Cleaned out the lathe and dropped the bolts that hold it to the frame. Tried the lever thing with a 2x3 and a thinner block under the ways. I could rock the lathe but not really lift the headstock significantly. Feels like the frame is giving or flexing. Didn't want to push it since it didn't feel particularly well controlled. The tubing is thin walled and I didn't want to lever against it for fear of it collapsing. I put a spreader on it but it didn't feel sturdy at all.

Think I will get my engine hoist out of my garage. It will have to disassembled it to get it into the basement, but at least the hoist will handle the weight with ease. Probably make it easier to line up the bolt holes with the weight off the stand. Looks like a job for tomorrow.

 

[WobblyHand]

The lathe has been lifted onto the riser blocks. Had a bit of fun figuring out how to get it done, but though bullheadedness did it. I did have to breakdown my engine hoist and bring it down into the basement piece by piece. Managed to lose a big M16 nut somehow. Dropped it, and watched it disappear under a juniper shrub. Couldn't find it for the life of me. Used a rake, a little hand hoe, flashlight, you name it. No nut. (Except me perhaps!) Had to go buy one to keep on going. Probably the first time in my life that I went to Home Depot, found what I wanted in less than a minute, and walked out of there in under 5 minutes tops. The nut was $1.25.

Reassembled the engine hoist in the basement. When I put the legs on I found they interfered with the screw lift for the wheels. Had to re-figure out how the heck to disassemble it to get the long screw out of there. The legs just fit under the lathe stand. To lift the lathe I used some 1" tubular webbing rated for 2000 lbs wrapped around the ways twice with a plank under the ways to protect the webbing from any sharp edges. Used a climbing knot to tie the ends together. Since the max lift was going to be 1-1/8" I didn't consider it unsafe. However, I did treat it as not quite safe, and never had my hands or body parts in place that could have been injured had the strap or hoist fail. That is just common sense.

The lathe didn't lift evenly, even though I tried to get as close to the headstock as possible. I ended up clamping the tail stock end using a big wood clamp to counteract the wall ward tilt and this enabled the headstock end to lift some. Had quite a time lining things up, but managed to finally have both risers lined up with the holes in the lathe, the chip pan and the frame. Once that was done, I dropped bolts in place from the top and lowered the lathe, using the bolts as guides. The bolts I have now are too short, need to order some, or maybe find them locally.

After a short rest, I will disassemble the engine hoist and get it out of my shop and back into my garage. Lot of work to do something seemingly simple!

With this out of the way, I can get back to installing the stepper motor mount plate. Since the riser is there, I can now drill and tap the casting without running foul of the chip pan.

 

[WobblyHand]

Arggh... Muffed one of the screw holes in the lathe. Unless I TIG braze up the hole, I will loose that position. I have another bench in the way, so it makes it hard to drill. (Can't fit a normal drill in there and use the bubble level on the hand drill.) Even though I used a transfer punch to mark the hole, the drill bit walked low AND the hole went in downhill. Dumb, dumb. Maybe I can open up the slot, I don't know.

Yeah, that was a couple of days ago. Today I decided to do some of the other holes. Decided to use my stubby 5mm drill. This time I left the plate in place, clamped it, used the transfer punch and drilled through the plate. Plus I used a square block to "indicate" the bit's squareness. That worked better. I could get the top two holes done. Tapped them to M6. Now I need to tackle the back lower screw hole. The jobber length 5mm drill (the one that walked) isn't long enough for the chuck to clear the pan, so I need to get an extended length drill bit.

In the meantime, I attached some belts and imagined it working. The encoder belt is too long for my liking, since it makes the feet of the bracket go past the front panel surface. So I ordered some shorter belts.

At some point I have to face the uncomfortable task of designing a PCB for Teensy, it's driver board and the display. It's only uncomfortable in the sense that it will be my first PCB board designed from open source tools. My last venture into designing a (different) board was stymied by a lack of models. I think this time I will use rows of holes as my model for the Teensy and the display. Won't make for a good schematic, but I should be able to make a simple board design that way.

 

[WobblyHand]

Well, I effed up the second bottom hole. My recovery plan is to lengthen the bottom slots and drill new holes in the casting. Sort of the best I can do at this point.

The bottom slots are now 1/2" longer towards the center. This should allow relocation of the drill holes on the bottom of the casting. Plan to make drill bushings and tack weld them to the motor plate, so I can get the holes straight. I was having an awful time drilling the holes. Reminds me - need to move the tool cabinet that is at the end of the lathe. Might as well make this easier to drill... At the moment the tool cabinet is 12" from the headstock end, which is not enough for me or the hand drill to get properly placed. Now I have to move 500 lbs of junk stuff.

 

[WobblyHand]

What I have so far. Two drill bushings and the two longer slots. Now making some locating pins for the bushings, so when I weld the bushings onto the plate, the bushings are aligned to the slot. The slots are 6.35mm wide (1/4") and the drill bushing ID's are 5mm.

The pins are 1/4" diameter for 20mm (the plate thickness) and 5mm diameter for about 20mm. Once the bushings are tack welded, plan to use a punch to remove the pins.

 

[WobblyHand]

I need to clean up the slots a little. They were plunge milled and then I connected the holes. On the side where the cutter would climb mill, the slot is still scalloped. I don't have a 3/16" end mill, nevermind one with 1" LOC. So I will have to slightly widen the slots so the pin slides smoothly. The slot is 1/4" and the screws are M6. Can't quite clean it up with a file. But anyways, here are the pieces.

The marker is where the new holes need to be. Hope to weld the guides in place this afternoon.

 

[WobblyHand]

Here they are mounted up on the lathe, about ready to drill. I was too lazy to change the wire in the Hobart Handler 180 MIG (from 0.023 to 0.030) so I just set it to 6/90 and splatted some tacks on the bushings. The welds are uglier than sin, but I'm going to knock and grind them off when I am done. Sort of afraid to whack them for fear they may come off prematurely, but they appear to be holding so far. Making the pins was a very good idea, since it held the bushings in the correct vertical spacing and centered in the slot.

The lazy person that I am, I haven't yet moved the tool bench out of the way. I should do this. That way I can more easily push the drill home. The extended drill that I bought is just barely long enough to do the job. The drill chuck will just kiss the pan at the correct hole depth.

 

[WobblyHand]

Finally, mounted the motor and set up the belt! Had to machine off the bosses. 5 out of 6 tacks had good penetration.

That motor will be staying put.

Next is the encoder mounting. Peeled off the front panel to see what was behind it. All the electronics of the lathe. However, if I put something there, like a plastic sheet, the drill chips shouldn't bother it.