G0602 Reverse Tumbler

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I was recently reading a post asking if the new Grizzly G0752 has the ability to cut left hand threads and it motivated me to finally make the conversion on my G0602.

http://www.hobby-machinist.com/threads/g0752-left-handed-threading.36983/

http://www.rcdon.com/html/the_reverse_tumbler_project.html

I've been putting off this project for years now because I have not once had a need to cut left hand threads, but I have wished that I could make right hand, auto feed cuts on several occasions.

I've researched a lot of different methods to do this and I settled with this one by RC Don that was in the above mentioned post. Clean, compact, simple and it didn't rob one of my threading gears like one person's did. Some people made a shifter out the front or top of the machine cover (very cool), but I don't want a permanent protrusion to get hung up on - for the few times I may need to make a gear change. Besides, I will more than likely need to open the cover anyway to change spindle speeds and this method only takes seconds to change the feed direction.

I used Don's blueprint/material list and it was very accurate up until the final mounting location on the casting, which is critical to the drive tooth engagement. With nothing 100% definitive from machine to machine, I used RC's guideline measurements and it worked out fine.

I made my upper clamping plate more compact. I felt that his was too big when I got right down to it. Everything worked out just as planned including the Delron gears ($30) and parts distributor. In order NOT to disable my lathe while making this mod, I purchased an extra shaft from Grizzly to modify ($7). Also, be sure and order a new ball oiler for the end of the new shaft ($2) because it doesn't come with one.

I ordered a new spindle/bull gear because my bull gear was very loose on the spindle shaft and I was getting some run out. The new gear was a perfect fit fixing a years old problem that I have just endured.

Also, I found the 2 locking spanner nuts are severely out of true (thread to face/wobblers) and I need to order a couple of those too. I do hope they got the new ones right... QC, come on Grizzly, they're only nuts!

Kudos though to Grizzly for their very good parts/order dept., low prices and quick service! Just check the online catalog, pick a part number and place your order. Parts arrived within days (sooner than they stated).

Rick

IMG_1944.JPG IMG_1945.JPG
 
I was recently reading a post asking if the new Grizzly G0752 has the ability to cut left hand threads and it motivated me to finally make the conversion on my G0602.

http://www.hobby-machinist.com/threads/g0752-left-handed-threading.36983/

http://www.rcdon.com/html/the_reverse_tumbler_project.html

I've been putting off this project for years now because I have not once had a need to cut left hand threads, but I have wished that I could make right hand, auto feed cuts on several occasions.

I've researched a lot of different methods to do this and I settled with this one by RC Don that was in the above mentioned post. Clean, compact, simple and it didn't rob one of my threading gears like one person's did. Some people made a shifter out the front or top of the machine cover (very cool), but I don't want a permanent protrusion to get hung up on - for the few times I may need to make a gear change. Besides, I will more than likely need to open the cover anyway to change spindle speeds and this method only takes seconds to change the feed direction.

I used Don's blueprint/material list and it was very accurate up until the final mounting location on the casting, which is critical to the drive tooth engagement. With nothing 100% definitive from machine to machine, I used RC's guideline measurements and it worked out fine.

I made my upper clamping plate more compact. I felt that his was too big when I got right down to it. Everything worked out just as planned including the Delron gears ($30) and parts distributor. In order NOT to disable my lathe while making this mod, I purchased an extra shaft from Grizzly to modify ($7). Also, be sure and order a new ball oiler for the end of the new shaft ($2) because it doesn't come with one.

I ordered a new spindle/bull gear because my bull gear was very loose on the spindle shaft and I was getting some run out. The new gear was a perfect fit fixing a years old problem that I have just endured.

Also, I found the 2 locking spanner nuts are severely out of true (thread to face/wobblers) and I need to order a couple of those too. I do hope they got the new ones right... QC, come on Grizzly, they're only nuts!

Kudos though to Grizzly for their very good parts/order dept., low prices and quick service! Just check the online catalog, pick a part number and place your order. Parts arrived within days (sooner than they stated).

Rick


Hi All
I was not aware that anyone made a lathe without a reverse gear. For the odd time that left hand threads are needed it would probably be easier to mount the cutting tool on the back side and run the spindle in reverse.
Just a thought
 
Hi All
I was not aware that anyone made a lathe without a reverse gear. For the odd time that left hand threads are needed it would probably be easier to mount the cutting tool on the back side and run the spindle in reverse.
Just a thought
That doesn't work. You will just be threading out instead of in towards the headstock.
 
Correct me if I'm wrong here, but couldn't you use tumbler to thread normally (right hand) BUT thread away from work piece instead of into it? In other words, not have to stop before getting to bolt head/gutter, rather just threading to end of bolt?
 
Guns -
Here's a quick rule of thumb: If the leadscrew and spindle are both turning in the same direction, you'll produce a right-hand thread. Reversing the direction of the spindle (by reversing the motor) will determine whether you're threading toward or away from the chuck, without changing the handedness of the thread. If the leadscrew and spindle turn in opposite directions, you'll get a LH thread. Setting the relative rotation direction of the leadscrew is done with the tumbler.
 
So hypothetically speaking, if I just switched my VFD to reverse, i could attain right hand threads but thread away from the chuck instead of towards it? I guess that feature exists already then as the lathe came stock with that ability?
 
You got it. Just set the threading tool upside down ... and be cautious if your chuck happens to be threaded on.

For further info, see Joe Pi's video:
The tool orientation is shown at about 4:30 in the video.
 
This link/document shows the permutations of left/right, external/internal, upright/inverted cutter combinations. (And other useful information even though its kind of orientated to inserts.)

Depending on whether your lathe can directionally feed independent of motor spin direction may dictate which options are available to you. Also as mentioned, if you have screw-on vs camlock (pinned) chuck mounting, that usually precludes running the chuck in reverse because of the risk of unscrewing itself.

'Conventional' upright tool infeeding to chuck seems to be burned into peoples DNA, but its probably because of the smaller and/or more limited lathes we grew up on. Many of the Asian import lathes are not limited in this way so we may have more options available to us that mitigate the knuckle chewing excitement of releasing thread engagement within a groove or before a shoulder.
 

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I appreciate the input and the chart. I know it's difficult around here sometimes as many people are very seasoned here and they're here for like minded people. Then there are others (like myself) that are here to learn from the aforementioned. Some are very happy to give/shape/teach, you guys are very much appreciated.
I know this isn't the place to pose this question, but I'm pretty sure I can (capacitors?) To my VFD for braking purposes, this would be huge for the whole "threading excitement" you spoke of.
'Conventional' upright tool infeeding to chuck seems to be burned into peoples DNA, but its probably because of the smaller and/or more limited lathes we grew up on. Many of the Asian import lathes are not limited in this way so we may have more options available to us that mitigate the knuckle chewing excitement of releasing thread engagement within a groove or before a shoulder.
 
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