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Grizzly G0768 Lathe DIY Powered Lead Screw & DRO

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Greg Madrigal

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Hi guys. First time poster here. I wanted to share my experience regarding the G0768 since there is very little online about it. I am hoping this will help somebody else tackle these issues. All in all, I am at very happy with my modifications.

I realize that in order to turn the wooden fly fishing reel seats that I want to turn, I would need to slow down the lead screw dramatically from me speed of the main spindle. This could only be done with an after-market motor. I had the bright idea to use an old Bosch drill that I had laying around because of a faulty trigger switch. I had since bought a new one so I had lots of fresh batteries hanging around to use for this purpose. At first I just mocked it up and created a cradle off the end of the lathe bed. I simply attached a 3/8 in socket adapter into the check of the drill along with the socket that fit the end of the lead screw. But I quickly realized was that I would need some sort of on/off switch with the ability to adjust the speed and forward and reverse. I hit up eBay and found a nice little motor controller that not only had the F4 mentioned options, but a bonus digital readout showing a percentage of full speed. This at least gives me some idea of where I should be dialing to for a specific task. I wrapped all of this up into a steel double gang outlet box with a plastic panel front that I made.

Also, I could not figure out how to eliminate most of the backlash from the cross slide. I decided a DRO was the only way to go for this since it doesn't rely on the threads of the screw but actually measures the distance at the cross slide moves. I had a little bit of trouble figuring out where I was going to place it but decided on the right side of the Cross slide. I was thinking of putting in a left and right microswitch to avoid Carriage collisions, but I left them out for the time being because I felt like there was a lot of wires and electronics around the work area as it was. Being that I use would mostly, that stuff gets everywhere! But I still May install the emergency switches down the road. If anybody has any ideas on how to do that, I am all ears. I landed on an Igauging 6in DRO. I'm pretty happy with it so far in testing but haven't had a good chance to use it.

This whole build cost me approximately $65. I wasted 16 of those dollars on a motor control unit that I accidentally burned up when I connected it to the motor while the motor was still connected to its Electronics in the trigger. For whatever reason, this fried it .

I am open to any questions but will leave most of the talking to the photos.
 

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RJSakowski

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Hi guys. First time poster here. I wanted to share my experience regarding the G0768 since there is very little online about it. I am hoping this will help somebody else tackle these issues. All in all, I am at very happy with my modifications.

I realize that in order to turn the wooden fly fishing reel seats that I want to turn, I would need to slow down the lead screw dramatically from me speed of the main spindle. This could only be done with an after-market motor. I had the bright idea to use an old Bosch drill that I had laying around because of a faulty trigger switch. I had since bought a new one so I had lots of fresh batteries hanging around to use for this purpose. At first I just mocked it up and created a cradle off the end of the lathe bed. I simply attached a 3/8 in socket adapter into the check of the drill along with the socket that fit the end of the lead screw. But I quickly realized was that I would need some sort of on/off switch with the ability to adjust the speed and forward and reverse. I hit up eBay and found a nice little motor controller that not only had the F4 mentioned options, but a bonus digital readout showing a percentage of full speed. This at least gives me some idea of where I should be dialing to for a specific task. I wrapped all of this up into a steel double gang outlet box with a plastic panel front that I made.

Also, I could not figure out how to eliminate most of the backlash from the cross slide. I decided a DRO was the only way to go for this since it doesn't rely on the threads of the screw but actually measures the distance at the cross slide moves. I had a little bit of trouble figuring out where I was going to place it but decided on the right side of the Cross slide. I was thinking of putting in a left and right microswitch to avoid Carriage collisions, but I left them out for the time being because I felt like there was a lot of wires and electronics around the work area as it was. Being that I use would mostly, that stuff gets everywhere! But I still May install the emergency switches down the road. If anybody has any ideas on how to do that, I am all ears. I landed on an Igauging 6in DRO. I'm pretty happy with it so far in testing but haven't had a good chance to use it.

This whole build cost me approximately $65. I wasted 16 of those dollars on a motor control unit that I accidentally burned up when I connected it to the motor while the motor was still connected to its Electronics in the trigger. For whatever reason, this fried it .

I am open to any questions but will leave most of the talking to the photos.
Some interesting work. I have a G0602 myself which I believe is essentially a larger version of your lathe sans the VFD.

A project that I am working on is an auto release for the half nuts which is essentially an electrical limit switch and is capable of working from both left and right. In my application, I will use a switch to activate a solenoid which in turn will disengage a seer and "fire" a rod which disengages the half nuts.
In your case, it will be much simpler since you are all electric. I put optical homing/limit switching on my Tormach 770 which is repeatable to .0002" but that would be overkill for you. The OEM limit switches on the machine use a microswitch with a ramp, the purpose of the ramp being to trigger the switch but not cause a hard crash if you overshoot for some reason. It is repeatable to around .002". Grizzly uses electric limit switches for the power feed on their G0755 mill which are interesting. Rather than the ramp, they use a spring loaded plunger which allows a fair amount of overshoot to activate the switch.

There are a number of projects on this forum which involve adding carriage stops to lathes. They involve making some sort of clamping arrangement for the stop and a fixed stop, a micrometer stop, or a dial indicator stop. If you replaced the stop with a microswitch mechanism, you would be half way there. I would use steering diodes aso that if you were moving left and hit the stop, left movement would be deactivated but you could still move right. The same idea for moving right.

I understand your concern about the wires in the working area. I addressed this by running my wiring through flexible stainless steel conduit. If you look at my lathe DRO project, https://www.hobby-machinist.com/threads/another-lathe-dro-install.34106/ you will see them.
 

ozzie46

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RJ, How do you lock the saddle when taking a cut? Or adjust the gibs with th scale on the right side of the saddle?

Ron
 

RJSakowski

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RJ, How do you lock the saddle when taking a cut? Or adjust the gibs with th scale on the right side of the saddle?

Ron
I have to remove the scale cover and the scale to adjust the cross slide gib. It isn't problem because that adjustment is infrequent and the process is quick and easy. There is a gap between the scale mount and the cross slide for an open end wrench to access the jam nuts. The gap is covered with plugs during normal use to prevent chips from falling in.

I can (just barely) access the carriage lock along side the scale cover. The 602 doesn't have a cross slide lock. I can easily add one as I have six threaded holes for a secondary mount of the compound that are currently plugged with set screws. I can make a soft point (copper or Delrin)for one set screw and lock my cross slide that way. A better solution would be to drill and thread another hole just forward of the left hand oiler. That would bear on the non contact area of saddle rather than the ways.
 

Greg Madrigal

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Thanks for all the kind feedback guys. I forgot to ask about ideas for covering the DRO from dust /chips
 

hman

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Nicely done! Do you see any unevenness in the motion due to the "looseness" of the socket adapter?
 

mattthemuppet2

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Nice work Greg!

A project that I am working on is an auto release for the half nuts which is essentially an electrical limit switch and is capable of working from both left and right. In my application, I will use a switch to activate a solenoid which in turn will disengage a seer and "fire" a rod which disengages the half nuts.
I saw a really neat solution on here a while back which used a spring loaded lever that was triggered by a push rod mounted to the lathe bed. Seemed very repeatible and robust.
 

RJSakowski

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Nice work Greg!



I saw a really neat solution on here a while back which used a spring loaded lever that was triggered by a push rod mounted to the lathe bed. Seemed very repeatible and robust.
I saw that as well and it was an inspiration for my design. My concern with that was that I would have the push rod to contend with. I decided to use a solenoid instead. Instead of a direct release, the solenoid releases a seer, much like the triggering mechanism on a firearm or crossbow. That way, a relatively weak solenoid can release a fairly strong spring for a crisp action of the half nut lever. The design also allows manual use of the half nut lever.

Here is a preliminary view of the mechanism shown in a cocked position. Activating the solenoid will pull down the lever, releasing the sear which will allow the bolt to move to the left, thereby releasing the half nuts. It is cocked by rotating the half nut lever clockwise which will simultaneously engage the half nuts an move the bolt to the right which will reset the seer. There are a still few parts missing from the design.
 

Greg Madrigal

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Greg Madrigal

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Some interesting work. I have a G0602 myself which I believe is essentially a larger version of your lathe sans the VFD.

A project that I am working on is an auto release for the half nuts which is essentially an electrical limit switch and is capable of working from both left and right. In my application, I will use a switch to activate a solenoid which in turn will disengage a seer and "fire" a rod which disengages the half nuts.
In your case, it will be much simpler since you are all electric. I put optical homing/limit switching on my Tormach 770 which is repeatable to .0002" but that would be overkill for you. The OEM limit switches on the machine use a microswitch with a ramp, the purpose of the ramp being to trigger the switch but not cause a hard crash if you overshoot for some reason. It is repeatable to around .002". Grizzly uses electric limit switches for the power feed on their G0755 mill which are interesting. Rather than the ramp, they use a spring loaded plunger which allows a fair amount of overshoot to activate the switch.

There are a number of projects on this forum which involve adding carriage stops to lathes. They involve making some sort of clamping arrangement for the stop and a fixed stop, a micrometer stop, or a dial indicator stop. If you replaced the stop with a microswitch mechanism, you would be half way there. I would use steering diodes aso that if you were moving left and hit the stop, left movement would be deactivated but you could still move right. The same idea for moving right.

I understand your concern about the wires in the working area. I addressed this by running my wiring through flexible stainless steel conduit. If you look at my lathe DRO project, https://www.hobby-machinist.com/threads/another-lathe-dro-install.34106/ you will see them.

Good deal. Your conduit job looks nice! I found a video on YouTube which showed the way to correctly wire the two micro switches to become stops. This way allows you to still go the other way. I will post on the next reply....
 

Greg Madrigal

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Here is the wiring schematic I mentioned above. Note the two switches in the center which are the two X Direction limit micro switches.

Credit to amrPragmaticLee who posted a YouTube video with this schematic called "DC motor reversing switch with limit switches"
 

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RJSakowski

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Here is the wiring schematic I mentioned above. Note the two switches in the center which are the two X Direction limit micro switches.

Credit to amrPragmaticLee who posted a YouTube video with this schematic called "DC motor reversing switch with limit switches"
That should work great. The microswitches are used in the normally closed configuration. I used the same circuit less the speed control to change the position of a damper in my HVAC system.
 
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