1.5/1.5003 is only 99.98 % off. Turning 10 threads would still match the thread gauge.
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ER40 collet chuck
- Thread starter Brian H
- Start date
There is a discrepancy between the King instruction chart and the Grizzly reference table.
King instructs to mesh F-gear with 86T of the compound 86T/91T.
The Grizzly table tells us to “always mesh the F-gear to the 91T portion” of the 86T/91T combo.
King chart:
Grizzly table:
We know King does not produce the 1.5mm pitch thread.
Might be worth trying the Grizzly combo.
King instructs to mesh F-gear with 86T of the compound 86T/91T.
The Grizzly table tells us to “always mesh the F-gear to the 91T portion” of the 86T/91T combo.
King chart:
Grizzly table:
We know King does not produce the 1.5mm pitch thread.
Might be worth trying the Grizzly combo.
Divide by one less than the threads contained. Or by the number of grooves (which is one less than the number of lands.
Fwiw, I always like to measure from start to start not center to center.
Yes, number of grooves is a better way to say it = the white spaces in my sketch. Land is the (blue) positive bit, even though we seem to always call those the 'threads'.
I sketched them as rectangular because of lead screw subject but usually I'm measuring V threads where center peak is maybe easier to caliper. But the divider, N, is still number of grooves within regardless of leading edge to leading edge, trailing edge to trailing edge, or center peak to center peak. So lets run with that!
@PeterT reminds me that it's a good time to introduce some silly stuff.
It's always bothered me that we count our age after each birthday. So we are not one until after our first birthday. Yet the year before that is our first year. The year after that first birthday is our second year. But we are not two until the end of our second year.
I think it would better all the way around if we did that with integers or items, but also for continuous things. Imagine how much better the world would be if we stopped counting boundaries and counted intervals instead.
Then again, I'm the idiot who wishes that we hadn't included our thumbs when we developed our counting system. The Octal number base is soooooo much better than decimal. Question: Which is better - imperial or metric? Answer: Both are junk - Octal is the superior choice by a VERY WIDE MARGIN! There is only one problem. I'm the only idiot who thinks so!
It's always bothered me that we count our age after each birthday. So we are not one until after our first birthday. Yet the year before that is our first year. The year after that first birthday is our second year. But we are not two until the end of our second year.
I think it would better all the way around if we did that with integers or items, but also for continuous things. Imagine how much better the world would be if we stopped counting boundaries and counted intervals instead.
Then again, I'm the idiot who wishes that we hadn't included our thumbs when we developed our counting system. The Octal number base is soooooo much better than decimal. Question: Which is better - imperial or metric? Answer: Both are junk - Octal is the superior choice by a VERY WIDE MARGIN! There is only one problem. I'm the only idiot who thinks so!
I had that same argument with my son when he was 5. He figured he was actually 6. His argument actually made a lot of sense.
Now I don't know.... The phrase I believe is you have 1 year birthday which implies you are 1 year old and you've been around for 1 year.
One could say we have one "Birthing" day and after that celebrate that as a Birthday.
Not logical to use the number zero because that really, in the history of humans hasn't been around all that long. Recall both the Romans and before them the Greeks did not have a symbol for zero.
But this is all a little off topic for turning a 1.5mm thread.
There's a saying that History doesn't Repeat but it does Rhyme. Back in around 2006 my second article published in Circuit Cellar Magazine talked about a method of getting rid of all those pesky gears. It was before the idea of 3D printing that one gear that was missing from the old war surplus metal lathe. It spawned discussions on various forums as people talked about the problems of getting accurate metric gears from imperial lathes.
Now 18 years later the rhyme is there. Nothing much has changed other than maybe printing a 127T gear and getting the ratios perfect which would have been much harder back then. But in that 18 years one thing hasn't changed. My self built Gingery with the 10 TPI ACME leadv screw makes perfect 1.5mm threads in a piece of ABS drain pipe.
What took the longest in this exercise was finding the 60 degree HSS threading tool. The threading took just over a minute.
One could say we have one "Birthing" day and after that celebrate that as a Birthday.
Not logical to use the number zero because that really, in the history of humans hasn't been around all that long. Recall both the Romans and before them the Greeks did not have a symbol for zero.
But this is all a little off topic for turning a 1.5mm thread.
There's a saying that History doesn't Repeat but it does Rhyme. Back in around 2006 my second article published in Circuit Cellar Magazine talked about a method of getting rid of all those pesky gears. It was before the idea of 3D printing that one gear that was missing from the old war surplus metal lathe. It spawned discussions on various forums as people talked about the problems of getting accurate metric gears from imperial lathes.
Now 18 years later the rhyme is there. Nothing much has changed other than maybe printing a 127T gear and getting the ratios perfect which would have been much harder back then. But in that 18 years one thing hasn't changed. My self built Gingery with the 10 TPI ACME leadv screw makes perfect 1.5mm threads in a piece of ABS drain pipe.
What took the longest in this exercise was finding the 60 degree HSS threading tool. The threading took just over a minute.
Kids always see complicated things much clearer than we adults do.
To your point, we certainly don't have a zeroeth year. I never liked zero any more than the Greeks or Romans did. I don't like zero and I don't like infinity either. But yet I'm quite happy with 0.00000001 or 10^300, with solid matter being mostly empty space, and looking back in time 2.5 million years with my naked eye.
Zero & Infinity....... - I no like.
Brian H
Super User
My first go at metric threading has been a little frustrating. I have gone through all your responses and done my best to follow all the suggestions and advice and here is where I am at.
-leadscrew thread pitch is confirmed to be 8TPI.
-I cannot easily reverse the 91/86T gear orientation, there is a center hub/spacer that is pressed into the gear. Also, the upper gear hub/shaft isn't physically long enough to bring that gear out far enough to engage the 91T portion of the center gear.
-I have tried all the combinations of gears/settings on the grizzly chart and get VERY different results than the chart...
-I have done my best to confirm the threading clamshell is fully engaged (awkward mirror/light setup)
While using @PeterT's method of measuring using and indicator and rotating the chuck it seemed like the rotation of the chuck got slightly different results on each of the 5 rotations which brought me to thinking something is not quite right somewhere. I can't thing of how gears would "slip".
Mention was made of a fork not engaging correctly in the gear box, what would the process be to check this. This is my first gear head lathe and although I know the theory of gear boxes I don't know where to start checking for engagement/alignment.
I just passed the 3 month period that King recommends an oil change in the gear box ( I was planning to do it this weekend anyway), so, now is probably a great time to open up and check what I can.
-leadscrew thread pitch is confirmed to be 8TPI.
-I cannot easily reverse the 91/86T gear orientation, there is a center hub/spacer that is pressed into the gear. Also, the upper gear hub/shaft isn't physically long enough to bring that gear out far enough to engage the 91T portion of the center gear.
-I have tried all the combinations of gears/settings on the grizzly chart and get VERY different results than the chart...
-I have done my best to confirm the threading clamshell is fully engaged (awkward mirror/light setup)
While using @PeterT's method of measuring using and indicator and rotating the chuck it seemed like the rotation of the chuck got slightly different results on each of the 5 rotations which brought me to thinking something is not quite right somewhere. I can't thing of how gears would "slip".
Mention was made of a fork not engaging correctly in the gear box, what would the process be to check this. This is my first gear head lathe and although I know the theory of gear boxes I don't know where to start checking for engagement/alignment.
I just passed the 3 month period that King recommends an oil change in the gear box ( I was planning to do it this weekend anyway), so, now is probably a great time to open up and check what I can.
Proxule
Ultra Member
If you have the king 12x36 lathe. Then this chart is exactly what you could or should fallow for any and all combos of threads. I have tried several random ones on my most recent threading adventures. They all checked out.
I suspect your gear mesh or mixup in the banjo is your issue.
Gluck
Been reading with interest. "Brian H", have you turned any other threads with this lathe? If this is the first set, and I seem to recall this is a fairly new lathe to you. Anyway a couple of things to check that I can think of, can you get the multipliers/dividers of the 1.5 mm thread? These are 3mm and 1.75, these are with the same gear setup and only the movement of the letter gear box lever. "B" position -1.5 mm, "A" position -3mm, "C" position -1.75mm.
Is there a key on the idler gear hub to hold the gears in place? A fiction fit will not do the job unless "very" tight. My lathe has a key and a tight fiction fit,( a pain). And needless to say, there should be keys in the driving and driven shafts also. I notice there does not appear to be anything holding the gear on the input shaft to the gear box.
A lathe that has seen use threading may not get a positive/consistent engagement of the clamshells (wear). Also try to get slack out of the gear train with each pass before cutter and thread engagement, sometimes a bit of pressure towards tail stock helps, pulling back a bit with a hand.
If all of this checks out, maybe try cutting a few imperial threads to see if there is a problem there also. My lathe was not cutting the right threads for the gear box indicators and was a problem in the gear box selector being out of time from a pervious dis/reassemblely by someone. This was in a post about a year ago.
I hope some of this may help, and there is an answer, just have to find it.
Don't know about the headstock gears, maybe to do with metric lathe/imperial lathe, or another size of lathe using same gear box.
Is there a key on the idler gear hub to hold the gears in place? A fiction fit will not do the job unless "very" tight. My lathe has a key and a tight fiction fit,( a pain). And needless to say, there should be keys in the driving and driven shafts also. I notice there does not appear to be anything holding the gear on the input shaft to the gear box.
A lathe that has seen use threading may not get a positive/consistent engagement of the clamshells (wear). Also try to get slack out of the gear train with each pass before cutter and thread engagement, sometimes a bit of pressure towards tail stock helps, pulling back a bit with a hand.
If all of this checks out, maybe try cutting a few imperial threads to see if there is a problem there also. My lathe was not cutting the right threads for the gear box indicators and was a problem in the gear box selector being out of time from a pervious dis/reassemblely by someone. This was in a post about a year ago.
I hope some of this may help, and there is an answer, just have to find it.
Don't know about the headstock gears, maybe to do with metric lathe/imperial lathe, or another size of lathe using same gear box.
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I noticed that as well.
My guess would be for our friends running 50Hz motors to get the spindle speeds as posted.
At any rate, the location of these “alternate” gears do not influence in any way your threading problem as they only affect the spindle speed itself.
Brian H
Super User
Thanks for you input.
Yes, this is a new lathe, and my first attempt at threading of any kind. I hadn't thought of trying the other thread options with that setup and measuring them. I will try that.
The gears are all keyed and have set screws. The lower gear is almost a press fit on the shaft. I have to gently tap it on and off.
I will also try to thread an imperial thread to see how it compares.
And, not that this is super relevant, but I just completed the first oil change and all of the forks, bushings set screws all seemed to be as they should be. There is no extra play in any moving parts. All movements are smooth and firm.
I was quite pleasantly surprised how little "stuff" was in the oil. One thing I'm glad I did before I filled it for the first time was placing two magnets at the bottom to collect metal shavings etc. They had some fine gritty stuff on them but were very easy to clean off and reinstall.
@Brian H As posted above...fundamentals as @Bandit suggested. Does this lathe cut any threads accurately? Make a table and systematically check and write down the expected versus measured for various combinations. Compare power feed vs lead screw to see if the results are as expected. If just one of your gears in the train is poorly made then all of this could result. Test different situations.
To get your project done you could buy a M50 die M50 Die search on amazon
To get your project done you could buy a M50 die M50 Die search on amazon
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I agree with the above comments. Make sure other thread settings are also accurate.
First set up to cut an 8 TPI thread and turn the spindle by hand and see if the lead screw is 1:1. Then try a 16 TPI thread where you should see two spindle turns for every single lead screw turn. Try turning a 24 TPI thread on something and see if it matches a 10-24 screw for thread pitch. These are all even multiples of your lead screw.
Then try something that isn't like 20 TPI. If that works now go for the Imperial Pipe Threads like 27 and 11.5 TPI. If those are all correct then it's possible the metric transposing setup isn't set up to be accurate. I always thought a 127T gear was mandatory.
First set up to cut an 8 TPI thread and turn the spindle by hand and see if the lead screw is 1:1. Then try a 16 TPI thread where you should see two spindle turns for every single lead screw turn. Try turning a 24 TPI thread on something and see if it matches a 10-24 screw for thread pitch. These are all even multiples of your lead screw.
Then try something that isn't like 20 TPI. If that works now go for the Imperial Pipe Threads like 27 and 11.5 TPI. If those are all correct then it's possible the metric transposing setup isn't set up to be accurate. I always thought a 127T gear was mandatory.
Lots of great ideas and suggestions here @Brian H .
Right now I can only think of one more piece of Engineering wisdom for you.
"This problem too will be simple once solved."
It may not seem like that right now, but I can assure you that it is true. And when you reach that point, you will be in great shape to advise others. There is nothing like a difficult problem to give us volumes of wisdom.
I agree with the idea of cutting all the other threads the lathe is capable of. If you cut them all very shallow, it becomes easy to measure them. It's also easy to clean them off to get ready for the next one. It wouldn't take much plastic pipe to do that and it's easy to vaccuum up all the plastic swarf when you are done. This may prove nothing, or everything. But even nothing is something.
Right now I can only think of one more piece of Engineering wisdom for you.
"This problem too will be simple once solved."
It may not seem like that right now, but I can assure you that it is true. And when you reach that point, you will be in great shape to advise others. There is nothing like a difficult problem to give us volumes of wisdom.
I agree with the idea of cutting all the other threads the lathe is capable of. If you cut them all very shallow, it becomes easy to measure them. It's also easy to clean them off to get ready for the next one. It wouldn't take much plastic pipe to do that and it's easy to vaccuum up all the plastic swarf when you are done. This may prove nothing, or everything. But even nothing is something.
I'm confused too. It doesn't help that the King manual references gears B,A,D but the chart refers to F,(blank),G And they never refer to the tooth count of idler specifically
We are trying to correlate to Grizzly which uses same F & G reference, but refer to idler as being 86 or 91. But now I'm reading their chart more carefully - ALL of the 1.5003 pitches fall under G-step = 86. Does G-step mean the idler? If that's the case then no combination using 91T equates to 1.5003 pitch. One 91T combo yields 1.5009 (pretty close) with gears 26-91-40 + levers B-5