thread measurements 13/4X8 T.P.I.

[lathe nut]

Hello all, I am in the progress of restoring a Carroll, 6" dividing head, it has all the plates and all the pieces, it has the 1 3/4 X 8 T.P.I. I want to make a back plate and a thread protector, I have not been able to find the thread information on that odd size, would someone have them or point me in the direction to fine them, from what I gather the last ones were made in the 1950's, a scrap hauler stopped by the house and said " I know that you do some machine work that I was going to the scrap yard and this was on the job I just cleaned up and a few other things take what you want, I like to passed out when I saw the dividing head and all the parts, he would not take any money he said that it would not bring more than 3-4 dollars, I was so excited, thanks you all in advance, Joe

 

[Scott_M]

It was in the Machinery Handbook, here is a photo of the specs

Scott

 

[SmithDoor]

Hello all, I am in the progress of restoring a Carroll, 6" dividing head, it has all the plates and all the pieces, it has the 1 3/4 X 8 T.P.I. I want to make a back plate and a thread protector, I have not been able to find the thread information on that odd size, would someone have them or point me in the direction to fine them, from what I gather the last ones were made in the 1950's, a scrap hauler stopped by the house and said " I know that you do some machine work that I was going to the scrap yard and this was on the job I just cleaned up and a few other things take what you want, I like to passed out when I saw the dividing head and all the parts, he would not take any money he said that it would not bring more than 3-4 dollars, I was so excited, thanks you all in advance, Joe

You plug that matches the dividing head use the wires.
The plug is to test fit as thread the backing plate.

Dave

 

[L98fiero]

Hello all, I am in the progress of restoring a Carroll, 6" dividing head, it has all the plates and all the pieces, it has the 1 3/4 X 8 T.P.I. I want to make a back plate and a thread protector, I have not been able to find the thread information on that odd size, would someone have them or point me in the direction to fine them, from what I gather the last ones were made in the 1950's, a scrap hauler stopped by the house and said " I know that you do some machine work that I was going to the scrap yard and this was on the job I just cleaned up and a few other things take what you want, I like to passed out when I saw the dividing head and all the parts, he would not take any money he said that it would not bring more than 3-4 dollars, I was so excited, thanks you all in advance, Joe

Here's a calculator that will cover all the 60° Unified threads, you can even come up with your own specials. UN imperial screw thread calculator
And one for 60° metric ISO Screw Thread Calculator

 

[GRAUBELE]

Hello together

Here in Germany, we have a company near me that provides almost all of the known thread standards in table form.
The nice thing about it is that the homepage can be switched from German to English.
Maybe this is useful here in the forum because many exotic threads are listed there.
Best regards Dieter

International Thread Standards

 

[mcostello]

I tried the metric calculator and it took the minor diameter down to 15 places. Hope I can hit that dimension!

 

[lathe nut]

Thanks so much guys, with all that information sure hope to figure it out, someone told me that it is probably a 4 or 5MM thread, not doubting him I had to order me a set of Metric gear teeth gauge did not have on with that big of teeth, sure hope it is not metric, did not expect to have a Carroll dividing head with that kind of thread, that would really present a problem, then to find a back plate to fit the new chuck, will keep you up with this fellows, thanks again for the information which was saved to folder and printed, Joe

 

[awake]

Lathenut, you're probably already thinking this, but just in case - if it were me, I'd make a trial piece or two out of sacrificial material to test the measurements I came up with. In my case, I'd probably start with a 3d print just to make sure I'm in the ball park.

 

[timo_gross]

I tried the metric calculator and it took the minor diameter down to 15 places. Hope I can hit that dimension!

It should not be a problem at all, you just machine close. The last 13 digits you can trimm by adjusting the temperature .

 

[SmithDoor]

I tried the metric calculator and it took the minor diameter down to 15 places. Hope I can hit that dimension!

I have use the thread wires a lot. Most time need was on Spindles. But all need there was to match the thread.

In machine shops they have a wall of nuts in NC , NF and LH.
Today in metric too.
They just use feel for fit it is basic but works even on cnc work.

Dave

 

[lathe nut]

I have some Delrin, going to try and cut some threads before I do the internal one but if worse comes to worse, I will take the dividing head apart and have a real machinist cut me some 1 1/2 X 8 T.P.I. that was I can if have to ever switch from Lathe to dividing head or the other way, I did measure and it is 4 T.P.I. Metric.

 

[Richard Hed]

I have some Delrin, going to try and cut some threads before I do the internal one but if worse comes to worse, I will take the dividing head apart and have a real machinist cut me some 1 1/2 X 8 T.P.I. that was I can if have to ever switch from Lathe to dividing head or the other way, I did measure and it is 4 T.P.I. Metric.

What the **?? is 4 TPI Metric? No such thing. Are the threads 8 tpi or not? If they are 8 tpi, you will have no trouble cutting the threads. 1-1/2" is wide enough to easily be able to see inside to watch what you are doing. I've cut a couple of the same size threads for an Enco 9". On the last one I cut, I broke the half-nut. Soon after, I got a real lathe and didn't need the 1-1/2 8tpi . I must have made too deep a cut on that last bit.

I forgot what size lathe you are using, but I know you can do it if your lathe has 8tpi capabilities. Most do. Anything less, ie, 6 or 4 tpi, most small lathes will not do. Just take it slow and don't do what I did and take too heavy a cut.

 

[abby]

4 tpi metric ! reminds me of visiting the local timber yard for some 3x2 , the assistant said we don't have 3x2 anymore , it's 75x50 now we are metric.
O.K I said , how much is it ? it's 20p a foot he replied.
Dan.

 

[lathe nut]

Richard Hed, I only ask for help, I apologize for getting you up set and causing you to curse me and to be angry, guess I don't know what I was referring to when I put 4 T.P.I. I put the metric gauge on the threads and fit perfect with the 4 threads per inch (T.P.I.) I will justify my decision for what I did, today I will take a picture of it with the number on the gear gauge, I was going to cut it on an Atlas 12" I have cut some 5 threads per inch on it, again sorry I up set you will post picture of it tonight, Joe​

abby, I can appreciate that one, that is like going to the lumber yard and saying you want a 2X4 but it not the size of a 2X4, went to a local band sawmill and asked the fellow for some 2X6, then I asked are they going to measure 2X6, he said yes this is not a mass merchant, I cut the size you want.​

 

[Richard Hed]

Richard Hed, I only ask for help, I apologize for getting you up set and causing you to curse me and to be angry, guess I don't know what I was referring to when I put 4 T.P.I. I put the metric gauge on the threads and fit perfect with the 4 threads per inch (T.P.I.) I will justify my decision for what I did, today I will take a picture of it with the number on the gear gauge, I was going to cut it on an Atlas 12" I have cut some 5 threads per inch on it, again sorry I up set you will post picture of it tonight, Joe​

abby, I can appreciate that one, that is like going to the lumber yard and saying you want a 2X4 but it not the size of a 2X4, went to a local band sawmill and asked the fellow for some 2X6, then I asked are they going to measure 2X6, he said yes this is not a mass merchant, I cut the size you want.​

not a wory, wasn't upset or angry, just want to know what you have .

 

[lathe nut]

not a wory, wasn't upset or angry, just want to know what you have .

Well guess I misunderstood with the Language you used, then I ow you an apology, I have attached some pictures to show the 4MM thread gauge, I am trying to find a back plate with those threads to fit a 6" chuck, that all.

 

[Scott_M]

Lathe nut
I think the confusion is in the terminology that you used. A metric thread is measured in mm per a single pitch not per inch. So your 4mm pitch gauge would mean that from the crest of one thread to the next would be 4mm.
Imperial threads are measured as how many in an inch( TPI ) If you want to know the TPI of a 4mm pitched thread you would divide 1" by 4mm 1" / .1575" = 6.35 or 6.35 TPI.
No harm no foul just terminology. I think we all knew what you meant just worded poorly.

Scott

 

[Richard Hed]

LOL, Scott pikt the problem. Actually, I'm laffing at my own foo-ishness. I forgot that others who don't use the metric system of threads don't usually understand the terminology at first (I didn't, anyway). So it's I who should be apologizing to Lathe Nut. (that's why I said "which is it?")

As far as that photo, certainly looks like a 4m. Am surprized that A Carrol has metric. I thot Carrol was US made. Am I wrong? (I was wrong about something once before.) Well, if you are going to cut 4m threads, you're going to need a lathe that is capable of cutting the thread size first of all. Am almost certain that a small lathe will not do it. I have a Grizz 12X36 and am not sure it will do it.

However, if you have a ltathe that is capable of cutting 4m, it still will need to be done carefully. If your capable lathe is small, then I would suggest that you do NOT cut the full depth of thread the first time thru. This makes a very difficult procedure, as you will not be able to test the thread against a standard. And INSIDE threads, at that! If it were me, I would make a compromize: cut half the thread deapth to within about .015" (somewhere near a fingernail thickness) of a full 4m, then increase the depth to the full and proper depth. Then you should have a good thread but not complete. Last, I would procede VERY slowly on the final cuts, only taking .002 or .003 (or even less if the lathe is having a difficult time cuttin it.).

I'm sure there are other solutions, one of which you might try your hand at making your won tap. It might work.

Ah, I chekt the Grizz and it will do the 4m, and even up to 4.5m. Even with that capability, me thimpfks I would cut about half the depth first as state d above.

 

[pete]

What your doing is basically no different than making a back plate for any lathes threaded spindle. In general, most would recommend starting out by machining your own thread gauge that matches the wire measurement as closely as possible over both the dividing heads spindle threads and your thread gauge. With that made, it's then used to gauge the thread fit as your cutting the much harder to accurately measure internal back plate thread. Yes it's extra work, but it guarantees a trial run that your thread pitch is correct. And once your thread gauge does properly fit the back plate threads your machining, then it will on the spindle of your dividing head without any uncertainty.

But a back plate for what type of chuck? Most seem to chose the standard 3 jaw chuck by mistake because of there convenience. Even my 10" Vertex dividing head came with a 3 jaw. To me and unless you have a proper set true type of 3 jaw chuck, there simply not accurate or repeatable enough for most work a good dividing head would be used for. A 4 jaw independent chuck while much slower to use, would be the far better choice. Even more so if you contemplate doing any gear cutting at some point. Threaded spindle noses on dividing heads are a carry over from back when many lathes also had threaded spindle noses. If your current lathe has a different spindle mounting design, it might be better to instead machine a threaded adapter that fits the dividing heads spindle but will then accept whatever type of chuck mounting design your lathe uses. The convenience and time saving of removing the chuck and already concentric work from the lathe and bolting it directly to the spindle of the dividing head makes the extra work worth while in my opinion. That's exactly what I did with mine. So any chuck or face plate that can be used on my lathe can then be used on my dividing head.

 

[lathe nut]

cc

What your doing is basically no different than making a back plate for any lathes threaded spindle. In general, most would recommend starting out by machining your own thread gauge that matches the wire measurement as closely as possible over both the dividing heads spindle threads and your thread gauge. With that made, it's then used to gauge the thread fit as your cutting the much harder to accurately measure internal back plate thread. Yes it's extra work, but it guarantees a trial run that your thread pitch is correct. And once your thread gauge does properly fit the back plate threads your machining, then it will on the spindle of your dividing head without any uncertainty.

But a back plate for what type of chuck? Most seem to chose the standard 3 jaw chuck by mistake because of there convenience. Even my 10" Vertex dividing head came with a 3 jaw. To me and unless you have a proper set true type of 3 jaw chuck, there simply not accurate or repeatable enough for most work a good dividing head would be used for. A 4 jaw independent chuck while much slower to use, would be the far better choice. Even more so if you contemplate doing any gear cutting at some point. Threaded spindle noses on dividing heads are a carry over from back when many lathes also had threaded spindle noses. If your current lathe has a different spindle mounting design, it might be better to instead machine a threaded adapter that fits the dividing heads spindle but will then accept whatever type of chuck mounting design your lathe uses. The convenience and time saving of removing the chuck and already concentric work from the lathe and bolting it directly to the spindle of the dividing head makes the extra work worth while in my opinion. That's exactly what I did with mine. So any chuck or face plate that can be used on my lathe can then be used on my dividing head.