Brent H
Ultra Member
@YYCHobbyMachinist : yes indeed - Doctor Diesel is on call 24/7 - have to be in the control room for tie ups and departures in case the fan is hit!
New member from Thunder Bay
- Thread starter ShawnR
- Start date
Thanks for the pictures @ShawnR and your comments @Brent H . There sure is a big problem with consistency in those charts!
From the picture table on the front of the machine (assuming for a second it is correct), the machine for sure has a metric lead screw.
This is contradicted inside the manual by the partial table (because it only shows 1/n [TPI]) and does not repeat the supposed metric threading table found on the headstock.
We need to confirm a few things:
A) is the lead screw METRIC? Do you have metric and imperial thread pitch gauges? If you do, please measure the lead screw for us. Thanks.
B) in your second picture, the 127T gear with whatever is behind it to form the transposing compound gear would suggest that you are attempting an imperial thread (with the metric lead screw lathe). If that is in fact the intent, then you can not open the half nut after the initial engagement. You must stop the spindle at the end of the cut, back out the tool, reverse the spindle to bring the carriage past the starting point, stop the spindle, feed in with your tool a bit, start the spindle in forward to make your cut (half nut is always engaged), Repeat until you are done. The threading dial is not used in this operation.
C) if you intend to cut metric threads with your metric lead screw lathe, the 127T gear needs to be removed from the gear train.
D) the note on the headstock table (see red boxed area) is “Chinglish” for saying to put an idler gear in the spot to make up the space between the input (gear A) and output (gear D) gears - whichever one you chose does not matter, as long as the input and output gears are connected in a straight line (no compound gears allowed; compound gear is a gear made up of two gears with the same or different tooth count connected on the same shaft).
E) it might be advisable to turn the spindle by hand (power disconnected and out of gear for safety) so you can practice engaging/disengaging the half nut. Threading at 115 rpm (your lowest speed) takes practice and it is easy to “miss the mark” on the threading dial, especially with a coarse thread. Ideally your spindle speed would be down to 20-30 rpm for first attempts at threading. That would give you a fighting chance to see what is actually going on.
A lot to take in, I know.
We will help you with the tables once you get the above sorted out....
From the picture table on the front of the machine (assuming for a second it is correct), the machine for sure has a metric lead screw.
This is contradicted inside the manual by the partial table (because it only shows 1/n [TPI]) and does not repeat the supposed metric threading table found on the headstock.
We need to confirm a few things:
A) is the lead screw METRIC? Do you have metric and imperial thread pitch gauges? If you do, please measure the lead screw for us. Thanks.
B) in your second picture, the 127T gear with whatever is behind it to form the transposing compound gear would suggest that you are attempting an imperial thread (with the metric lead screw lathe). If that is in fact the intent, then you can not open the half nut after the initial engagement. You must stop the spindle at the end of the cut, back out the tool, reverse the spindle to bring the carriage past the starting point, stop the spindle, feed in with your tool a bit, start the spindle in forward to make your cut (half nut is always engaged), Repeat until you are done. The threading dial is not used in this operation.
C) if you intend to cut metric threads with your metric lead screw lathe, the 127T gear needs to be removed from the gear train.
D) the note on the headstock table (see red boxed area) is “Chinglish” for saying to put an idler gear in the spot to make up the space between the input (gear A) and output (gear D) gears - whichever one you chose does not matter, as long as the input and output gears are connected in a straight line (no compound gears allowed; compound gear is a gear made up of two gears with the same or different tooth count connected on the same shaft).
E) it might be advisable to turn the spindle by hand (power disconnected and out of gear for safety) so you can practice engaging/disengaging the half nut. Threading at 115 rpm (your lowest speed) takes practice and it is easy to “miss the mark” on the threading dial, especially with a coarse thread. Ideally your spindle speed would be down to 20-30 rpm for first attempts at threading. That would give you a fighting chance to see what is actually going on.
A lot to take in, I know.
We will help you with the tables once you get the above sorted out....
@RobinHood your post #23 is a mouth full for this old codger with much to digest so I'll print off your post and double check my B2227L Craftex lathe tomorrow bum leg agreeing.
<snip> From the picture table on the front of the machine (assuming for a second it is correct), the machine for sure has a metric lead screw.
How did you determine that @RobinHood? When a guy buys a new lathe one finds himself in a world of new lingo if you have never been around a lathe before. Like falling out of a two story window and hitting the sidewalk runni
Meanwhile I offer this from my users manual and my lathe. Sorry about my second photo couldn't get it into a 1/4 turn right. So looking at the gearing photo and going from left to right without taking it apart it should be gear #30, then large gear #60 inner, small gear #35 outer, and the larger bottom gear #125. That is the way I received the lathe gearing from factory.
Basically my facts concur with what you speak to.
<snip> From the picture table on the front of the machine (assuming for a second it is correct), the machine for sure has a metric lead screw.
How did you determine that @RobinHood? When a guy buys a new lathe one finds himself in a world of new lingo if you have never been around a lathe before. Like falling out of a two story window and hitting the sidewalk runni
Meanwhile I offer this from my users manual and my lathe. Sorry about my second photo couldn't get it into a 1/4 turn right. So looking at the gearing photo and going from left to right without taking it apart it should be gear #30, then large gear #60 inner, small gear #35 outer, and the larger bottom gear #125. That is the way I received the lathe gearing from factory.
Basically my facts concur with what you speak to.
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@ShawnR, @Brent H, @RobinHood, for me the light just went on. Comparing Shawn's photo of his threading scale and that of mine there's a huge difference between the number of gears listed for each.
Shawn should have the following gear set according to his chart, #30-35-40-45-50-55-60-65-70-75-80-110-120-127 for a grand total of 14.
Now I understand how Shawn's lead screw is metric.
Dusty's gear set includes #30-35-40-45-50-55-60-63-65-70-80-98-100-105-120-125 for a grand total of 16.
It would appear my lead screw is designed for both imperial and metric, am I correct in thinking that?
Shawn should have the following gear set according to his chart, #30-35-40-45-50-55-60-65-70-75-80-110-120-127 for a grand total of 14.
Now I understand how Shawn's lead screw is metric.
Dusty's gear set includes #30-35-40-45-50-55-60-63-65-70-80-98-100-105-120-125 for a grand total of 16.
It would appear my lead screw is designed for both imperial and metric, am I correct in thinking that?
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Dusty, in @ShawnR ’s head stock picture, in the “1/n” ( TPI, or imperial threads) chart section (red boxed section) there is a 127T gear in position C. It gets paired with either a 45T, 60T, 75T, or a 120T gear (position B), depending which threads per inch (TPI) you want to cut.
One only needs that gear when going from a metric lead screw to imperial threads because there are 254mm /in. One could use a 254T gear, but that would be a rather large diameter gear. So what is commonly done, they take 254 and divide it by 2 to get 127T (this is a prime number and can’t be divided any more and still be a whole number). Gears can only be made with whole a number of teeth.
So the fact that there is a 127T gear in the drive train to achieve imperial threads, I know that the lead screw has to be metric. Conversely, if the 127T gear is in play when cutting metric threads, then the lathe has an imperial lead screw.
Dusty, now for your lathe (it is going to get complicated....)
It is the same model, but it does not seem to use the 127T transposing gear any more. They use an approximation to get the 127T ratio (100/127=0.787401) by using the 63/80 = 0.7875 combo. I don’t see any reference in your manual on how to use the threading dial. So we need to first confirm if you have a metric or imperial lead screw. Then we can offer a solution as to how to use it.
Please look at the red and yellow boxes in the photo below of your lathe set-up:
The red box denotes the available feed rates in inches of longitudinal feed per one spindle revolution. According to that chart, there are two speeds available: 0.0025”/rev and 0.005”/rev. Currently, you are set-up for the factory preset of 0.005”/rev. This is not a thread.
If you want to produce a specific thread, you need to find it in the chart and assemble your gear train accordingly. For example, if you want to cut a 1/2”-13 TPI thread, you need to put the 80T gear in position A, the 40T in B, the 70T in C and the 65T in D.
You are sort of correct: the lathe is capable of producing both some metric and some imperial threads.
Unfortunately a lead screw can not physically be both metric and imperial at the same time. It is either a metric lead screw that with the 100/127 transposing ratio can be “tricked” into acting like an imperial one. OR it is an imperial lead screw that again uses the 100/127 ration to “make” it into a metric lead screw.
At the end of the day it really does not matter if it is metric or imperial. The only thing that changes is how the operator uses the threading dial and the half nut.
Thanks Derek. Been to Tubalcain more than once. ThisOldTony is really good too. I enjoy his graphics he inserts (cartoonish) and his sense of humour. But, at the same time, very informative.
@RobinHood wrote, Dusty, now for your lathe (it is going to get complicated....)
It is the same model, but it does not seem to use the 127T transposing gear any more. They use an approximation to get the 127T ratio (100/127=0.787401) by using the 63/80 = 0.7875 combo. I don’t see any reference in your manual on how to use the threading dial. So we need to first confirm if you have a metric or imperial lead screw. Then we can offer a solution as to how to use it.
Please look at the red and yellow boxes in the photo below of your lathe set-up:
View attachment 13081
The red box denotes the available feed rates in inches of longitudinal feed per one spindle revolution. According to that chart, there are two speeds available: 0.0025”/rev and 0.005”/rev. Currently, you are set-up for the factory preset of 0.005”/rev. This is not a thread.
If you want to produce a specific thread, you need to find it in the chart and assemble your gear train accordingly. For example, if you want to cut a 1/2”-13 TPI thread, you need to put the 80T gear in position A, the 40T in B, the 70T in C and the 65T in D.[/QUOTE]
Yes you are absolutely correct SuperUser the B2227L Craftex manual that came with my lathe offers no information on using the threading dial. had to rely on videos to understand what I was up against like being between a rock and a hard place. My initial threading attempted was a 3/8" course thread so I stuck with that. After studying the gearing chart front face of my lathe I selected the correct gears, installed them and gave it a try. Although I fully understand one might not get it right the first time my threading process simply didn't work out and I couldn't understand the why. Finger not connecting to my brain says I.
Yes I understand the basics on how to determine and change the gear train for specific thread(s). This morning I took a serious look at my lead screw unsure how one determines if its metric or imperial although I assume metric. I need to work on that today.
Believe it all boils down to do I use the threading dial or not.
It is the same model, but it does not seem to use the 127T transposing gear any more. They use an approximation to get the 127T ratio (100/127=0.787401) by using the 63/80 = 0.7875 combo. I don’t see any reference in your manual on how to use the threading dial. So we need to first confirm if you have a metric or imperial lead screw. Then we can offer a solution as to how to use it.
Please look at the red and yellow boxes in the photo below of your lathe set-up:
View attachment 13081
The red box denotes the available feed rates in inches of longitudinal feed per one spindle revolution. According to that chart, there are two speeds available: 0.0025”/rev and 0.005”/rev. Currently, you are set-up for the factory preset of 0.005”/rev. This is not a thread.
If you want to produce a specific thread, you need to find it in the chart and assemble your gear train accordingly. For example, if you want to cut a 1/2”-13 TPI thread, you need to put the 80T gear in position A, the 40T in B, the 70T in C and the 65T in D.[/QUOTE]
Yes you are absolutely correct SuperUser the B2227L Craftex manual that came with my lathe offers no information on using the threading dial. had to rely on videos to understand what I was up against like being between a rock and a hard place. My initial threading attempted was a 3/8" course thread so I stuck with that. After studying the gearing chart front face of my lathe I selected the correct gears, installed them and gave it a try. Although I fully understand one might not get it right the first time my threading process simply didn't work out and I couldn't understand the why. Finger not connecting to my brain says I.
Yes I understand the basics on how to determine and change the gear train for specific thread(s). This morning I took a serious look at my lead screw unsure how one determines if its metric or imperial although I assume metric. I need to work on that today.
Believe it all boils down to do I use the threading dial or not.
Brent H
Ultra Member
@Dusty : Put a scale on the lead screw and count the threads over 1" - typical lead screw at 8 TPI will be pretty easy to see as the threads will all line up at the 1/8" markings. If it is a metric pitch it will typically have a very odd number of threads within that inch and things will not line up at the 1 inch mark.
Was just out was in the shop measuring my lead screw and it measures out like this. The lead screw measures 0.7880" / 20.01 mm diameter, there are 7 lands within 1 inch (six full lands and two halves), and my #7 imperial thread pitch gauge lines up perfectly with the center of the lands.
From your comments above and my calculations I say metric lead screw.
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Look what I found!
https://bbs.homeshopmachinist.net/forum/general/39936-threading-confusion-a-bit-long
In post #11 of the quoted thread, it shows clearly a 7TPI lead screw, like what you measured Dusty. And lo and behold in post #17 of the thread, they reveal the lathe: a BB2227L!
If you read through all the posts very carefully, it gives a good explanation of the threading dial use of this lathe (and any other lathe for that matter). Of particular interest is post #24!
So now we know that at least the newer models have an imperial lead screw.
Perhaps Shawn can chime in and confirm the lead screw on his BB2227L.
https://bbs.homeshopmachinist.net/forum/general/39936-threading-confusion-a-bit-long
In post #11 of the quoted thread, it shows clearly a 7TPI lead screw, like what you measured Dusty. And lo and behold in post #17 of the thread, they reveal the lathe: a BB2227L!
If you read through all the posts very carefully, it gives a good explanation of the threading dial use of this lathe (and any other lathe for that matter). Of particular interest is post #24!
So now we know that at least the newer models have an imperial lead screw.
Perhaps Shawn can chime in and confirm the lead screw on his BB2227L.
Brent H
Ultra Member
Bravo @RobinHood : that is great to find out - read that linked thread - Wow @Dusty - that is some crazy leadscrew but hopefully the new info it will help with threading on your lathe. The lead screw diameter must have been some out of whack engineering cheat to make something fit? 0.7915 is more than 20mm and less than 51/64's ....wow. No wonder confusion abounds!
Well,...I had great success today! Not as I expected but once I accepted that I must keep the carriage engaged, I found the process actually easier and less stressful than staring at the wheel, waiting for it to come around and trying to snag it at the exact moment! Here is the lead screw with a ruler so all can see what I have and compare to Dusty's description. Also, completed working threads! I cut the half inch first, then turned it down and cut 7/16 but only had the lock nut for the video. After cutting a longer thread, I ground out the nylok to use it as a regular nut. Figured it would not be impressive to slowly screw a nylok on versus spinning the nut onto the new thread!
Thank you everyone for all of the advice. As I stated over at ShopFloorTalk, I learned a lot about my lathe in the process, cleaned it up, got more comfortable with how the gears work and changing them and now have a pretty good handle on how to cut threads, although practice is in my future!
Here is the first successful thread test. The nylon is still in the nut so I only ran it till it hit.
Thank you everyone for all of the advice. As I stated over at ShopFloorTalk, I learned a lot about my lathe in the process, cleaned it up, got more comfortable with how the gears work and changing them and now have a pretty good handle on how to cut threads, although practice is in my future!
Here is the first successful thread test. The nylon is still in the nut so I only ran it till it hit.
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@Brent H, amended my lead screw diameter measurement in my Post # 32. Your comments above had me somewhat concerned so I returned to my shop with my trusty Mitutoyo calipers and micrometer in hand (don't usually store them in my shop). This time I wasn't in such a hurry measuring so my lead screw diameter measurement is smack on 20mm or 0.780 inch. Does this make more sense?
Having read Post #33 (Look what I found) and following the details I'm more confused than ever, not that it takes much. LOL
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Great work Shawn, so your lead screw has 9 lands per inch according to your photo. What diameter is your lead screw?
I measured 0.785 " diameter and 17 threads in 2 inches, so, yep, 7.5 threads/inch. Interestingly, I used a divider set to exactly 2 inches, and put it up against the leadscrew. The points fell perfectly onto the start of one thread and the start of the next thread 18 later, so that leaves 17 threads included in the 2 inches. 
If I did the math right on that, it comes out to 2.988 mm metric pitch so, I think it was mentioned before, a 3 mm pitch. The screw being 20 mm x 3 ? Make sense?
If I did the math right on that, it comes out to 2.988 mm metric pitch so, I think it was mentioned before, a 3 mm pitch. The screw being 20 mm x 3 ? Make sense?
Brent H
Ultra Member
Yes, it makes sense you have a 20 mm x 3 pitch lead screw. If you look at the gears required for 1.0 mm pitch it is a 60 on A , B can really be any gear and the 45 goes on D. this gives you a 1:1.333333 gear ration so with the 3 pitch lead screw you advance 1 mm per revolution or 1 mm pitch threading
@Dusty A few years back, I was on a kick to get more comfortable with changing the gears out. We are all different in what bugs us (pet pieve) but one of the things that bugged me was the number of different tools needed. 14 and 17 mm (iirc) sockets, phillips driver and 8 mm wrench, after you got into the end panel (6 mm allen key?...don't remember) just to swap gears, so, 5 different tools..... think about different feed rates for different finishes...UUUrrrrrrrrr! Of course, most feeding is by hand...
One great little project was combining those tools, mostly. I made a knurled nut for the panel fastener and then got some surplus sockets and welded up a tee wrench that combined all of the tools. It was a diversion away from actually getting comfortable with swapping gears, maybe, but as many times as I have swapped gears in the last three days as I worked through this threading dilemna, time well spent! Back then, I was active on Home Shop Machinist, another great site, and I found an old thread that I was part of. Check out post #11 and on.
https://bbs.homeshopmachinist.net/forum/general/70551-common-tool-feed-rate
Cheers,
Shawn
One great little project was combining those tools, mostly. I made a knurled nut for the panel fastener and then got some surplus sockets and welded up a tee wrench that combined all of the tools. It was a diversion away from actually getting comfortable with swapping gears, maybe,
but as many times as I have swapped gears in the last three days as I worked through this threading dilemna, time well spent! Back then, I was active on Home Shop Machinist, another great site, and I found an old thread that I was part of. Check out post #11 and on. https://bbs.homeshopmachinist.net/forum/general/70551-common-tool-feed-rate
Cheers,
Shawn
@Dusty A few years back, I was on a kick to get more comfortable with changing the gears out. We are all different in what bugs us (pet pieve) but one of the things that bugged me was the number of different tools needed. 14 and 17 mm (iirc) sockets, phillips driver and 8 mm wrench, after you got into the end panel (6 mm allen key?...don't remember) just to swap gears, so, 5 different tools..... think about different feed rates for different finishes...UUUrrrrrrrrr! Of course, most feeding is by hand...
One great little project was combining those tools, mostly. I made a knurled nut for the panel fastener and then got some surplus sockets and welded up a tee wrench that combined all of the tools. It was a diversion away from actually getting comfortable with swapping gears, maybe,
https://bbs.homeshopmachinist.net/forum/general/70551-common-tool-feed-rate
Cheers,
Shawn
Thanks Shawn, like your suggestion something to plan for and build at a later date.