# Is it posible to make a thread chasing dial?



## tarmo120 (Jan 23, 2013)

The lathe I got doesn't have that dial, you would use when threading. And because of that I need to keep the halfnuts connected and run the motor backwards after each cut.
I really hate that. This got me thinking, would it be possible to make my own thread chasing dial.
If this is not possible, I'll just have to live with what i've got.


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## DMS (Jan 23, 2013)

It should be possible. All a thread chasing dial is, is a gear that engages with your leadscrew, a dial with markings (usually 8), and a mount. The gear needs to be the right pitch to engage your leadscrew. It doesn't need to be a tight fit, just enough so that it doesn't jump around.


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## 12bolts (Jan 23, 2013)

Yeah, easy enough to make. Just count your leadscrew pitch and make your dial gear to suit, *important bit* keep the gear pitch in ratio relationship to the leadscrew. ie if your leadscrew is 8tpi then make the gear 16 or 24 tooth. for a 6tpi leadscrew, then 12, 18, 24 etc. Makes for easier re-engagement calculations on the threading dial marks.

Cheers Phil


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## ScrapMetal (Jan 23, 2013)

What kind of lathe do you have?  Would it be for metric, SAE threading, or both?  It will make a difference as to how many teeth you need and the markings on it else, as the others have said, it should be pretty easy to make one.

-Ron


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## darkzero (Jan 23, 2013)

If it's for that same Nova lathe you posted, you can see on the PM version what their's looks like. PM1127VF

May be easier to just purchase one but not sure if you'd be willing to spend that much on one. Grizzly has this one in stock for $117 which is for the G0602. I assume your lathe would have a metric leadscrew so you'd have to verify the gear pitch or just replace it. I only referenced Grizzly cause their the only one I know that lists & sells replacement parts online. Maybe try calling someone in your area.


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## GK1918 (Jan 24, 2013)

In my opinion making this can be kept simple you dont need overkill.  A couple of basic tools.  I have
done this and worked better than expected.  A block of mahogony an old exhaust valve and a piece of
delrin or similar.  The thought is, that this will not be towing a Mack truck. It practically has no load on
it.  I counter sunk the valve & drilled the block for the valve stem.  I brushed on the blackest grease/oil
on the lead screw and rolled the delrin to get the imprint (mine is acme) die grinder with cut off I cut
the teeth on the bench vice.  As you get a pretty good mesh thats good enough.  I dont know If you
have a mounting hole like south bends or you will have to drill one for a pin.  Valves are hard so I cherry
redded it so I could stamp lines and numbers (8).  The plastic driven gear is only hand pressed on the
valve.  I dont have to index or time this because I placed a large washer on the top & around the
valve with a witness mark so when I engauge the half nut just notice where and turn the ring or
washer to the number you wish to use.  Couple coats of kilz couple coats of gray and nobody can tell
its made out of wood.  I should Have said I counter sunk the valve with a forestner <(spelling) bit. 
I suppose if you have a flat spot on your cross slide you could glue a magnet to the new dial block. 
As I hate all the math most do for a simple little gear, the simple things are overlooked a foot print
is a footprint it will reveil all the angles pitches  fingerprints no math it works.


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## tarmo120 (Jan 24, 2013)

Yes I was wondering if I could make it for the Nova lathe. I would have asked around locally, but I bought the lathe from Finland and they don't sell any lathe with this dial.
So that means, they wont have any dials available.

I am very interested in your method, GK.
Could you explain to me how you cut the mesh on the pinion.
Did you make up a special cutter and milled it on a rotary table or what?

Oh yeah, and I'm 99% sure this lathe has a metric leadscrew. I can thread metric and imperial/inch threads with changing the gears.
I'm going to where the lathe is on friday, so I could check that leadscrew it is.
Is it written on something or in the manual or just look at it?


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## KMoffett (Jan 24, 2013)

This is one I made years ago for a South Bend lathe. I was fortunate enough to buy the gear just before South Bend folded.

Ken


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## tarmo120 (Jan 24, 2013)

This is all very nice and now I'm convinced I can make one. But my question is how did you cut the gear.
Because I'm confident you or I wont find a macthing gear.
If I have a matching gear for the leadscrew, the rest is very easy.


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## DMS (Jan 24, 2013)

It doesn't have to be an exact match, because you are not transmitting a lot of load. Figure out if your leadscrew is imperial, or metric, then figure out the pitch. Find a 16tooth gear with the same pitch,and it should fit, no problem. Even if you can't machine it, you may be able to find a small plastic gear for sale, or somebody on the board may be able to make one for you.

Making gears isn't too hard, Brian has a nice thread on building the tools and cutters needed to make clock gears.

[thread]9737[/thread]

I'm guessing your lathe is going to have a metric leadscrew that will mesh nicely with a standard metric gear.


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## 12bolts (Jan 24, 2013)

tarmo120 said:


> But my question is how did you cut the gear.


Tarmo, I think you have missed something in GK's post


GK1918 said:


> .....I brushed on the blackest grease/oil on the lead screw and rolled the delrin to get the imprint..........die grinder with cut off I cut the teeth on the bench vice.  As you get a pretty good mesh thats good enough. ......


He copied the leadscrew pattern onto the gear blank and then using a small grinder, Think Dremel tool, to cut the teeth freehand.

Cheers Phil


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## tarmo120 (Jan 24, 2013)

I think I did miss that.
Thanks for pointing it out. I'll take a closer look tomorrow evening.
Maybe even make a test piece.
How would I determine the diameter of the gear?


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## KMoffett (Jan 24, 2013)

tarmo120 said:


> This is all very nice and now I'm convinced I can make one. But my question is how did you cut the gear.
> Because I'm confident you or I wont find a macthing gear.
> If I have a matching gear for the leadscrew, the rest is very easy.


I'd didn't cut the gear.  As I said, I bought it from South Bend. 

Ken


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## Benji (Jan 24, 2013)

I have made a bunch of geqrs for the early South Bend Type 5 or #405 Workshop lathe. 
This has a LH l;ead screw so the gear is a bit different. 

Attached is my setup. This is for an 8 tpi leadscrew. The cutting tool is an ID ACME threading tool grund for 8 TPI.  The blank is set at about a 6 or 7 degree andle to match the lead of the screw. The loading is light so you do not need a concave gear. 
I moved the gear under the cutter so the profile is flat. If I wanted to get it complicated I could have set the tool to stick out thread rooth depth and moved the blank up and into the cutter and then down and index and then up and then down etc. But many of the SB gears were just this shape so why make it complicated. 

The material is Moly filled Delrin. That stuff is designed for gears.


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## GK1918 (Jan 25, 2013)

As 12bolts said, I simply got an impression therefore no math.  Can be done even with white paper
remember rubbing an eraser on paper over a penny.  Then I free hand cut the teeth with a cut off
wheel on a air die grinder.  NOTE one thing I forgot to say is, if your leadscrew is keyed the gear
blank will have to be dished out to the diameter of the screw.  Thats so it dont get stuck or jump
when the key comes around.  Now If you do not have a key a proper washer will do such as like
my big lathe is twin screw meaning the threading screw is not keyed so a washer works fine.
I still need a camara battery then you will see how easy it is.
One more if keyed the gear blank will have to be fat so when the key comes around a tooth is 
entering and a tooth is exiting (the keyway)


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## joe_m (Jan 25, 2013)

I have a box of small medium and large gears that I accumulated while collecting machinist chests. If  you can come up with specs for what kind of gear you need I can dig through it and see if anything fits. My experience is minimal so you'd have to provide a tooth count and something easy for me to measure like outer diameter or something. 

Tools4Cheap is selling a replacement (reproduction) thread dial for certain southbends for $100 if that might fit the bill. I don't know the specs for your lathe or for Southbend.

Joe


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## tarmo120 (Jan 25, 2013)

I will try to get the needed info tomorrow. Take some pics with dimensions and such.
And also try to figure out if the leadscrew is metric or non metric.


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## rafe (Jan 25, 2013)

*Re: Is it possible to make a thread chasing dial?*

I will need to make one for my 14 1/2 inch SB ....6tpi 1 1/8 screw ....I get the part about rolling the blank to mark it , but how do you determine it's(blanks) diameter..24t =4"circumference? I know that is not the proper way to describe a gear ....but will that work??..I see a 48 tooth on the Grizzly site for the thread dial they sell  (gear is $11 ) how do I determine if it will work on the 6tpi screw on my lathe??What do I ask them? I don't want to buy the whole thing ...just the gear...looks like it may be for a smaller lathe though.....this should be my first project on the 14 1/2...I will pick it up in the am ...very excited


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## tarmo120 (Jan 26, 2013)

That was my question also.
Today I have made a few pictures for you to see. And help me out determing the nature of the leadscrew. Metric or not.









The outside diameter of the leadscrew is 20mm or .786 inches.
Since I couldn't figure out if it a single thread or double thread screw I'm not sure on the TPI or Pitch.
I measured from the right side of one thread to the same side on the next one.
It measured 3.0mm or .115 inches.
And on the length of 1 inch I got 9 threads.
I did go through the manual 3 times and the only thing that could point to metric leadscrew is shown in the second picture. The thread table.


And then I googled a few hours and came up with this.
If indeed I have a metric leadscrew then I think I'm not going to mess with it. Just leave it be and work with I've got.



When I do threading I'll have 99% of the time metric threads.


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## joe_m (Jan 26, 2013)

I was googling/binging/yahooing for info on my own lathe today and came across another thread on another forum in a galaxy far far away. 

http://tinyurl.com/au5hf8m

Halfway down the page are some directions and it looks like, if I'm reading correctly, that all you need to know is the pitch of your leadscrew - which you've already established at 9tpi. Based on that, any 36 tpi screw with teeth that fit between the thread of your leadscrew should do the trick. 


Joe


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## Boot (Jan 31, 2013)

I'm not totally sure of this,but if you have a meteric lead screw a thread dial won't work.  You better ask around about this.  
I made one for my SB from plans I got from an article in Popular Science magazine of about 1941 or so vintage. 
In order to cut threads on a metric lathe you must keep half nuts engaged and reverse the motor. May not be 
true ,but I read or heard it somewhere.


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## darkzero (Jan 31, 2013)

Boot said:


> I'm not totally sure of this,but if you have a meteric lead screw a thread dial won't work. You better ask around about this.
> I made one for my SB from plans I got from an article in Popular Science magazine of about 1941 or so vintage.
> In order to cut threads on a metric lathe you must keep half nuts engaged and reverse the motor. May not be
> true ,but I read or heard it somewhere.



What is true is that if a lathe has a true imperial leadscrew, then the thread dial cannot be used to cut metric threads. So I just always assumed that true metric lathes with a metric leadscrew would be the opposite, be able to cut some metric screws conventially using the half nut & thread dial but to cut imperial threads they could not be used. I don't know much about cutting metric threads other than the few metric threads I have cut leaving the half nuts engagaed so I don't actually know the truth in this.

I have seen some true metric lathes online with 3mm or 6mm pitch leadscrews & they have thread dials.

PM's version of this lathe has an 8 TPI leadscrew


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## DMS (Jan 31, 2013)

I would guess based on what you have shown that you have a metric leadscrew with 3mm pitch. Hopefully somebody will correct me if I am wrong, but I believe that works out to a module 3 gear. For a 16T gear, the diameter of the blank would be 54mm (Number_of_teeth+2)*module. That's a decent size gear, if you drop down to 8 teeth, you end up with 30mm.

Will has good advice as well, If you have a metric leadscrew, you will only be able to use the threading dial to cut metric threads, for inch threads, you will steel need to reverse with the halfnut engaged. If it is a inch leadscrew, you will only be able to use the threading dial to cut inch threads. Still, probably better than no dial


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