# G9729 Left Hand Thread Cutting



## LX Kid

Doesn't seem to be that many people who have bought these machines.  Maybe that's some handwriting on the wall that I should have read somewhere.   I bought my Grizz G9729  beginning of last summer and have only been able to do anything with it in the last 30 days. The heat, here in Florida, just kept me out of the shop.  Anyway after a "lot" of modding and repairs I have it online to make some chips.  My biggest problem was the pivot gear was squeezing the rack gear.  I had to do some shimming of the cross-slide gear box to make it usable.

Now after rambling, has anyone made a reverse tumbler for their lathe?  These lathes have been around for long time and only thing I see is DC motor drive mods attached to the lead screw.  *I would prefer a mechanical idler gear to enable reversing the lead screw. * Anyone know?  I do have a treadmill  torn down, and ready to do mod, but have  but have been reluctant.


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## pdentrem

The late Steve Bedair added a tumbler gear to his 9x20 lathe. Check out his write up and MORE on his site. It will likely give you some ideas to fit your lathe.
Pierre


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## LX Kid

I had no idea that Steve Bedair had passed away.  I had visited his site many time in past years when I had my 9x20 lathe.  He and his talent will be missed by all.  Thanks

Is it possible to turn the cutter upside down and run the lead screw in reverse to cut left hand threads?


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## pdentrem

No. The cutter has to be ground properly as the angles will be on opposite sides. Use the tool in standard position with the leadscrew in reverse.
Pierre


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## LX Kid

There is no reversing the lead screw without reversing direction of chuck.  That's why I want to mod the lead screw direction in relation to forward turning of the chuck.


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## LX Kid

Think I'll keep my original idea of making the a variable speed lathe, with the treadmill stuff and just add another motor for the variable reversing of the lead screw.  On a variable speed feeding lead screw experimentation would have to be done to get the feed proper for different thread spacing.  I'd think a 1/5hp dc motor would do the job for lead screw.


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## pdentrem

Exactly, the tumbler reverse solves all the problems. Can you put an idler in the gear train to reverse the lead screw? You just need a single gear to do the job.


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## LX Kid

The way the the gears are set up makes it a little different than Steve Adairs' 9x20 lathe.


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## epanzella

LX Kid said:


> Think I'll keep my original idea of making the a variable speed lathe, with the treadmill stuff and just add another motor for the variable reversing of the lead screw.  On a variable speed feeding lead screw experimentation would have to be done to get the feed proper for different thread spacing.  I'd think a 1/5hp dc motor would do the job for lead screw.


If I understand you correctly you're gonna have one motor run the spindle and another run the lead screw? If the lead screw is not indexed to the spindle I don't see how you'll cut left hand threads or any other kind of threads.


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## LX Kid

Digital ratation counter in manual mode for different threads and then mark those speeds on the dial indicator of the new motor controller.


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## JimDawson

That will be an interesting way of doing it.  Please let us know how it works.


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## John Hasler

LX Kid said:


> Digital ratation counter in manual mode for different threads and then mark those speeds on the dial indicator of the new motor controller.


Not good enough.  For a given TPI the ratio of the spindle speed to that of the leadscrew must be *exactly* equal to the ratio of two particular integers.  This can be done with electronics but it can't be done by manually setting a speed control.


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## planeflyer21

This guy did what you're talking about:


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## LX Kid

Come to think of it your probably right!  Once the motor starts to load down the rpm's will drop and change the cut.  Well maybe it's time to go back to the drawing board !  An adjustable idler gear to reverse the lead screw is about the only way to go.


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## LX Kid

WOW!  He's what I'd have to call a "Master Machinist!"


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## LX Kid

This works.  Now all I have to do is figure out a slider rail/bracket to mount the gear.   Two thumb screws to replace the allen head screw will need to be added for ease of doing the change.  Also the rail/bracket can't block gear change procedure for different gear changes.  Gotta think this one out.


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## epanzella

LX Kid said:


> Digital ratation counter in manual mode for different threads and then mark those speeds on the dial indicator of the new motor controller.


To make threads you need to make multiple passes, backing out and backing up after each pass. The next pass has to be lined up exactly in the cut of the previous pass. I don't understand how that can be accomplished without a mechanical link between the spindle and the leadscrew. I've seen electric powered feeds before but they only worked for turning, not threading.


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## LX Kid

Take the lead screw out of gear (neutral), hand crank back to correct dial number and then re-engage lead screw.


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## epanzella

You're still relying on an electric motor to traverse the carriage EXACTLY in the previous cut with varying loads like DOC changes. It would be interesting to see if it's possible.


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## LX Kid

But remember in #14 above I scraped that motor idea and went back to the idler gear as pictured above.

Going to mount the idler gear from the bottom cause it will be easier to mount the slider bracket.


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## epanzella

LX Kid said:


> But remember in #14 above I scraped that motor idea and went back to the idler gear as pictured above.


Oh, I see that now. A while back I saw a video of a guy that made a tumbler for (I think) a Grizzly lathe. He did it by accessing the  first gear out of the headstock so it was up high and he could still change the gears below. It was pretty slick. I'll try to find it.


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## RJSakowski

epanzella said:


> Oh, I see that now. A while back I saw a video of a guy that made a tumbler for (I think) a Grizzly lathe. He did it by accessing the  first gear out of the headstock so it was up high and he could still change the gears below. It was pretty slick. I'll try to find it.


There have been a number of tumbler additions to Grizzly lathes.  I posted some drawings of what I had done to the G0602 here: http://www.hobby-machinist.com/threads/g0752-left-handed-threading.36983/#post-315574


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## John Hasler

LX Kid said:


> Take the lead screw out of gear (neutral), hand crank back to correct dial number and then re-engage lead screw.


The threading dial only works when the leadscrew maintains a precise phase relationship to the spindle.


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## LX Kid

Spent the day fabricating an idler gear assembly.   Will post pics later when wife comes back with the laptop from Girl Scout meeting.  All I could find to use was a piece of angle iron.  Looks terrible but will work.  Lathed out the idler gear shaft.


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## LX Kid

View attachment 120438

	

		
			
		

		
	
 After installing the bracket I found out that it does work but will have to be made more stable.  Going to cut off the bottom and weld the bracket to a 4x6" plate for more stability.

View attachment 120438


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## Fabrickator

I made a reverse tumbler for my G0602.  Maybe you can adapt this system to your model.

EDIT:  I didn't see that RJ had already posted a link that had the "RC Don" version, which is what I used.  Worked perfectly, gears were cheap, just made my F/R lever a bit shorted is all.


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## LX Kid

Just "who" wouldn't be invious of my welding?  Man what a "mess!"  My little HF welder just wouldn't cooperate!  Maybe I could touch it up with some Super Glue!


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## LX Kid

Fabrickator said:


> I made a reverse tumbler for my G0602.  Maybe you can adapt this system to your model.
> 
> EDIT:  I didn't see that RJ had already posted a link that had the "RC Don" version, which is what I used.  Worked perfectly, gears were cheap, just made my F/R lever a bit shorted is all.
> 
> View attachment 120465
> View attachment 120466



Don't think it would be feasible  the way mine is setup.  Have treadmill stuff already.  Just have to get my act in gear to get-r-done!  Hope there's now welding involved.  LoL


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## epanzella

What rod/amperage are you using? Assuming your HF buzzbox is an AC machine, 1/8 inch 6011 rod at 100amp (+ or - 10%)  should weld that up just fine.


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## LX Kid

90amp tig or mig.  I always get the two mixed up!  No gas just the wire feed which kept sticking and messing up!  There must be some kind of "You Failed" award given by this forum!  LoL

I could probably just Bondo up everything and paint it.  Who would know?


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## epanzella

LX Kid said:


> 90amp tig or mig.  I always get the two mixed up!  No gas just the wire feed which kept sticking and messing up!  There must be some kind of "You Failed" award given by this forum!  LoL
> 
> I could probably just Bondo up everything and paint it.  Who would know?



OK. You said wire so that's a MIG. You said "no gas" so that means you're using fluxcore wire, which works similar to the flux coated welding rods of a stick welder. As the flux burns it pulls impurities out of the weld and creates a shielding gas to prevent the oxygen in the air from contaminating the weld. If you're using regular unfluxed MIG wire it won't work without gas. If you're using flux cored wire (or plain MIG  wire with gas) DON'T blow the smoke away with a fan. It blows away the shielding gas. I'd bet the farm you're using unfluxed wire or a fan or both. Fix that weld, it doesn't look like it'll hold up two butterflies.


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## LX Kid

Yup, it's a MIG with flux wire.  I popped the hood to see what's going on and the spool was a little too tight and adjust the wire feed rollers.  The wire now comes out the end in a constant flow instead of "herky jerky" no "worky!"  I also tapped the bracket with a small ball peen and like "exanzella" said it just fell off.  Glad a couple of butterflies weren't on there!  LoL  I cleaned all the "welding warts" off both pieces with a grinder.  Put everything in a plastic bag for another day.  Next year is looking good!!!


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## pdentrem

Don't be afraid to preheat the steel a bit. Makes for better welds for machines that are not powerful enough on heavier gauge materials.


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## LX Kid

Here's my $40 wonder machine.    Meaning "I wonder why I  bought it!"  Couldn't be the machines operator.


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## epanzella

Can't read the model but that should be fine for what you're doing. There's a spray for keeping spatter from sticking to your contact tube. Get some if you can.


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## JR49

On a mig welder, I believe if you switch from using solid wire with shielding gas, to flux cored wire you need to reverse the polarity.  I Got an incredible deal on a little used Lincoln 110V mig.  The seller said he just couldn't learn to use it.  His welds looked just like yours, so I paid what he wanted (very little), brought it home, read the instructions, which clearly explained having to reverse the polarity (your HF instructions may not have been clear on this),  and it's been welding fine for 2 years now.  Good luck,  JR49   PS,  If you need any kind of welding advise, there are some very knowledgeable guys over on the welding sub-forum


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## Fabrickator

Check your polarity.  Wire is opposite from Flux Coated.  Also make sure you have a good, "clean steel" ground setup.


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## LX Kid

Fabrickator said:


> Check your polarity.  Wire is opposite from Flux Coated.  Also make sure you have a good, "clean steel" ground setup.



Pretty sure it was because the wire feed was out of adjustment and the coil of wire was too tight.  Gonna give it another try next week.  Got a roof leak that ruined my living room ceiling to deal with at the moment.


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## partsproduction

"WOW! He's what I'd have to call a "Master Machinist!""

A master machinist would buy a master machinist's lathe. The guy who made the "Home made lathe" is probably a master tinkerer. A master machinists wouldn't waste time on reinventing the wheel.

I can hardly believe anyone would sell a lathe without a simple tumbler. Shame on Grizzly.

I have a Drummond lathe sold in England 75 years ago that came without a tumbler, but I really find it amazing that anyone would sell one now without one. At the very _least_ they should sell an optional tumbler.​


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## LX Kid

partsproduction said:


> "WOW! He's what I'd have to call a "Master Machinist!""
> A master machinist would buy a master machinist's lathe. The guy who made the "Home made lathe" is probably a master tinkerer. A master machinists wouldn't waste time on reinventing the wheel.
> I can hardly believe anyone would sell a lathe without a simple tumbler. Shame on Grizzly.
> I have a Drummond lathe sold in England 75 years ago that came without a tumbler, but I really find it amazing that anyone would sell one now without one. At the very _least_ they should sell an optional tumbler.​




In this case, Grizzly, "You pay less you get less!" 

I never learned to cut threads yet, but it seems that even when I get the idler gear installed,  and I have to change the gears around for different thread pitches, it may not even work for left hand threads.​


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## planeflyer21

Re: master machinists, used to be when Henry Ford ran Ford in the early days they had a simple test to get hired on as a machinist.  With hand files, file a round hole to a 1" square and file a round bar to a 1" square to fit in the hole, all four directions, with 0.004" clearance.

IMO talking about whether a machine tool has certain features or not making the machinist a master is a distraction.  If you are able to make a part to specifications with the tools you have (hand or machine), you're off to a good start.


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## LX Kid

Yes I agree with that 100%.  Look what 3rd world country's do with just had tools.  For instance the Pakistani's making fine firearms sitting on the dirt floor using files, cheap grinder two batteries as their arc welder.  I've see things done in the Philippines that were just unbelievable.   They have done so much, for so long that they can do anything with nothing!   (They've come al "long" way since I lived there is the '60's and 70's)  Some of the more successful have been able to get hold of a lathe.   And to think I complain about my crappy Chinese 3-in-1 lathe!

This getting away from half nut discussion but heck this out!


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## LX Kid

I'm thinking the reversing gear is going to have to be done in a different configuration.  If any one of the gears is changed to another, for different thread, then the gear won't be engaged with the lead screw gear.   Gonna have to give this some thought and see who has some suggestions for me!


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## pdentrem

How much room is there between the spindle gear and the firsts gear on the gear quadrant, if you swing it the full distance away from the spindle. What I envision is a tumbler gear set between those 2 gears instead of your current first choice. Makes for a more normal set up.


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## Johnnybar

LX Kid said:


> 90amp tig or mig.  I always get the two mixed up!  No gas just the wire feed which kept sticking and messing up!  There must be some kind of "You Failed" award given by this forum!  LoL
> 
> I could probably just Bondo up everything and paint it.  Who would know?


Looks like your polarity is reversed assuming you were using innershield wire.  With innershield wire, the work ground is the positive lead.  If you were using solid wire, no gas is not an option and the work ground is the negative lead.


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## tmarks11

LX Kid said:


> 90amp tig or mig.  I always get the two mixed up! No gas just the wire feed


MIG.

TIG uses rods, not wire feed.

Not surprising it looks like hell without using a cover gas (or self shielded wire). It also looks way too cold.  1/4" plate on a 110V box s tough.


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## Johnnybar

Forgot to mention, you can use the factory bracket to mount an idler gear when cutting most LH threads.  Just use the smallest final gear option and add a stud to the unused center slot for an idler.


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## Johnnybar

LX Kid said:


> Doesn't seem to be that many people who have bought these machines.  Maybe that's some handwriting on the wall that I should have read somewhere.   I bought my Grizz G9729  beginning of last summer and have only been able to do anything with it in the last 30 days. The heat, here in Florida, just kept me out of the shop.  Anyway after a "lot" of modding and repairs I have it online to make some chips.  My biggest problem was the pivot gear was squeezing the rack gear.  I had to do some shimming of the cross-slide gear box to make it usable.
> 
> Now after rambling, has anyone made a reverse tumbler for their lathe?  These lathes have been around for long time and only thing I see is DC motor drive mods attached to the lead screw.  *I would prefer a mechanical idler gear to enable reversing the lead screw. * Anyone know?  I do have a treadmill  torn down, and ready to do mod, but have  but have been reluctant.



Many common threads do not require anything other than another gear stud inserted in the unused center slot for a reversing idler.  What LH threads are you expecting to cut?


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## Johnnybar

Pictures are worth a thousand words........this is geared for 6, 12, 24 tpi.  

LX Kid, With that large final gear in the pics you posted, it looks like the gearing you set up to run in reverse is for fine feeding instead of threading....if I'm wrong, it won't be the first time!


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## Johnnybar

Here's a LH 6 tpi test run....


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## cookj320

Is it flux core wire?


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