# Tumbler reverse for 9x20 Imported lathe



## joesmith (Nov 6, 2011)

I have 2 9x20 lathes. I bought the Harbor Freight  about 6 yrs ago on sale because it was a bargain. A short time later I traded an extra Drill Mill for a Grizzly with the factory stand.  I cleaned and "set up" the 2 lathes and have used them regularly.  I have larger lathes and never felt the need for the tumbler reverse for threading.  However I found that I was constantly disengaging the gear train to make short  cuts and for polishing.

This summer I decided to make the tumbler for my lathes and for a machinest friend who is struggling with cancer.

After studying various posts on the net I decided to follow the plans posted on the Yahoo 9x group with several mods
.
I made the knob with a 60 degree taper that screws into an enlarged hole in the slot to lock the tumbler into reversed, forward and neutral positions.
A brass ring is attached to the knob to facilitate knurling.  My cheap knurls didn't want to handle the hardened stainless steel.

The bushings have oversized holes to permit precise alighnment of the gears.

I made 4 of these tumbler units.  I have an extra if anyone is interested.  

Joe

My next project is installing my Sinpro dro on my Enco mill.


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## ScrapMetal (Nov 6, 2011)

Pardon my ignorance guys but could you please explain what a "tumbler reverse" is (although I'm pretty sure I've got it figured out, just want to verify) and why it is necessary on these lathes.  Could the same thing be accomplished by reversing the motor?  Why or why not?

Just trying to learn a bit here for future reference.

Thanks,

-Ron


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## joesmith (Nov 6, 2011)

Revesing the motor on a lathe also reverses the direction of the leadscrew and spindle.  To cut left hand threads you need to retain the spindle direction while reversing the direction of the leadscrew.  The tumbler reverse in the reverse position engages an extra idler gear which causes the leadscrew direction to reverse.  The tumbler can also be placed in the neutral position which disengages most of the gear train and the leadscrew.  I use the neutral position more ofter than the left hand turning.  Note that your Southbend has a tumbler reverse.  Most of the industrial lathes do.


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## ScrapMetal (Nov 7, 2011)

Thanks Joe, nice explanation.  Yes, my SB has a funky "safety" lever for reversing (at least I seem to remember reading about it in "How to Run a Lathe").  I just haven't come across a situation where I've needed to put it to use as of yet. 

-Ron


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## SyLord (Jan 10, 2013)

I know this is an old thread, but does anyone have any pictures of the gears, the whole setup installed?

i purchased a HF 9x20 about 5 years ago.   I did what I thought was right to break it in by cleaning, lubing, and running it to wear it in, but the gear shafts (screw in with oil fill) and found one to be caked with thick crud stopping the oil and it caused a gear to lock up, spin the threaded shaft (which is held by a set screw) stripping the threads, shattering a gear, the nylon gear, and some other minor carnage.  

After 8 months of fighting with Harbor Freight customer service in China to get the $150 in parts, and them sending me wrong or only part of the parts, I decided to order the tumbler reverse package from a little machine shop that advertised on Yahoo's 9x20 lathe group.   The company was moving (?) and I got my order in on a last clearance price,mas well as a new donut and some other upgrade parts, got them, and didn't get any instructions, had some family issues, and it sat until now.  

I had to do some fitting of the kit, but figured it out, and addressed clearance issues and have it installed, but the two smaller stacked gears, the bottom meshes with the larger (80t?) gear but the smaller upper gear does not contact anything.  

I was just hoping to see some other picture of this setup on other 9x20's so I can see how they are setup 

Thank you,
Darrell


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## Mikkell (Dec 30, 2018)

joesmith said:


> I have 2 9x20 lathes. I bought the Harbor Freight  about 6 yrs ago on sale because it was a bargain. A short time later I traded an extra Drill Mill for a Grizzly with the factory stand.  I cleaned and "set up" the 2 lathes and have used them regularly.  I have larger lathes and never felt the need for the tumbler reverse for threading.  However I found that I was constantly disengaging the gear train to make short  cuts and for polishing.
> 
> This summer I decided to make the tumbler for my lathes and for a machinest friend who is struggling with cancer.
> 
> ...


I know this is prolly a stupid question but do you still have one of these available?


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## savarin (Dec 30, 2018)

This was the one I made along with all the other bits I needed to finish it or correct the mistakes.
https://www.hobby-machinist.com/threads/tumbler-reverse.10122/
It was a well worth doing project and taught me heaps.
The aluminium gear is still in place and going strong.


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