ELS on Mini-Lathe?

Okay, I'll fire away here then.

The servo motor drive has 3 inputs from Clough42's interface PCB. Namely, STEP, DIRECTION, and ENABLE. The signals going to the the drive are differential. Typically, the "+" inputs are tied to +5V and the STEP, DIRECTION, and ENABLE pins from the interface PCB are connected to the '-' inputs. So, that would make all of them active low. Yet, in the code, there are defines for these that are set as follows:
// #define INVERT_STEP_PIN true
// #define INVERT_DIRECTION_PIN true
#define INVERT_ENABLE_PIN true

This implies the ENABLE pin is active low (as it should be), but the STEP and DIRECTION pins are active high. Isn't this wrong?
 
Okay, here's my next question. I plan on running the encoder directly coupled to the geared main spindle. See photo in post #15 and red circled shaft. So, I don't need any pulleys for this. I'm designing a mount for this now.

I'm looking at getting pulleys for the lead screw. Clouth42 uses a 3:1 ratio and I'm planning on using the same hybrid stepper motor. I'm assuming this will give me good performance (torque and speed) since my lathe is smaller than his. So, do I order HTD 3M pulleys and belts? Any recommended vendors?
 
By directly coupled, I assume you mean a hard coupling or similar? There's nothing wrong with that, but you need to know the gear ratio to that point so your ELS knows how much the spindle moved. You can just count the teeth and calculate the ratio, then use that to calculate the pulse count for the encoder in the code.

I used HTD5M, but I doubt you would have any trouble with the smaller 3M belts, and they would probably fit better on the mini lathe. I bought from these ebay vendors, shipping from China is always a bit slow, but it works. Amazon had a couple of people selling parts, but the variety wasn't very good. I just ordered a variety of belt sizes and used the one that best fit.

https://www.ebay.com/usr/rubberbeltsonline
 
ttabbal said:
By directly coupled, I assume you mean a hard coupling or similar? There's nothing wrong with that, but you need to know the gear ratio to that point so your ELS knows how much the spindle moved. You can just count the teeth and calculate the ratio, then use that to calculate the pulse count for the encoder in the code.

Yes, I plan on mounting the encoder with the shafts facing each other and in line with a simple coupler machined for each shaft diameters. I think the gear ratio is 1:1, but I'll double check.

I used HTD5M, but I doubt you would have any trouble with the smaller 3M belts, and they would probably fit better on the mini lathe. I bought from these ebay vendors, shipping from China is always a bit slow, but it works. Amazon had a couple of people selling parts, but the variety wasn't very good. I just ordered a variety of belt sizes and used the one that best fit.

Okay, I'll check them out. Thanks. I need to work out the motor mounting. I'm thinking of placing it on the banjo somehow so I can adjust the tension on it.
Click to expand...
 
Another question. This time on the encoder.

The Omron encoder has outputs labelled: A, B, and Z. The TI LaunchPad Evaluation Board has a header for encoders and they are labelled: 1A, 1B, and 1I. I'm assuming A goes to 1A and B goes to 1B, but does Z go to 1I? From the Omron datasheet, it's hard to tell what Z does. Is it 1 pulse per revolution?
 
I remember wondering the same and hooked it up as you guessed, and it worked fine.
 
Here's some drawings of what I'm thinking for mounting the encoder.
 

Attachments

  • Assembly1.pdf
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  • Assembly2.pdf
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I have the same enclosure that Clough42 used. It's a Hammond CHKO18126. I'm about to start mounting the components in it. However, the sheet metal is 16 gauge thick. Is this thick enough to drill and tap? Or, do I need to drill straight through and use a nut and washer? I don't have much experience with sheet metal. Thanks!
 
devils4ever said:
I have the same enclosure that Clough42 used. It's a Hammond CHKO18126. I'm about to start mounting the components in it. However, the sheet metal is 16 gauge thick. Is this thick enough to drill and tap? Or, do I need to drill straight through and use a nut and washer? I don't have much experience with sheet metal. Thanks!
Click to expand...

16G. is .06" thick. I would use sheet metal screws , a threaded insert, or nut and washer; your choice.
 
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