# Help with faceplate threads



## schemer (Sep 30, 2017)

A while back I bought a used 2 1/4 - 8 TPI slotted faceplate for/from a southbend lathe to use in a project. I also bought a new threaded backplate adapter for a chuck with the same 2 1/4 - 8 TPI thread. Fast forward to getting around to project and now I have a problem. I made an adapter for the project and cut a 2 1/4 - 8 TPI thread and it works fine on the new adapter but will not go into either side of the South Bend used faceplate. I am guessing the threads got banged on both ends but I need to fix it. It looks like the best bet (although expensive) is to buy a tap and run it through the threads. I know you can "chase" a thread and I have done it before on external threads, but never even cut an internal thread. Is it possible to repair this with a trick I don't know of like using a threading tool as a scraper or some wierd thing?
Thoughts?
Thanks,
schemer


----------



## Technical Ted (Sep 30, 2017)

It's really hard telling not seeing the thing in person, but I would be suspicious that it was truly 2 1/4 - TPI if it doesn't fit at all.... Does it really look like both ends are that pounded up? Usually, the threads are recessed so they don't get damaged. 

Do you have any way to check the major diameter of those internal threads? Like a pair of old fashion internal calipers or something? You should be able to at least check the TPI with a scale.

Good luck,
Ted


----------



## Dave Paine (Sep 30, 2017)

As Technical Ted mentioned, confirm the threads on the faceplate are 8 tpi.  I am presuming the diameter is 2 1/4in.   You should be able to easily confirm the pitch with a thread gauge.

You can make your own tap to chase the internal thread.  Machine a piece of stock to 2 1/4in x 8 tpi, then grind hollows so you have 2, 3 or 4 flutes.  This should work for fixing any damaged thread.  Machine a taper on the front as you would see on a tap.


----------



## Zathros (Sep 30, 2017)

It helps If you would own à threading file.



Grts the other Ted.



Verzonden vanaf mijn iPhone met Tapatalk Pro


----------



## schemer (Sep 30, 2017)

Thanks for the replies guys. I have a thread file so I will check and see if it has an 8 tpi section and check it. The adapter I made starts to screw in for approximately 1/8 of a turn. I guess I could make a thread chaser tap but I need to see if I have a chunk of 2 1/4 laying around or get one. I have some cheap screw thread gauges but no 8 tpi on them. I need to get on ebay and buy some Starrett ones. With a 6 inch scale I measure approximately 2 1/4 on the faceplate and the threads really look ok to me. I am guessing when I bought it I assumed the ebay seller knew what he had and it looked good to me when it arrived but I had no way of checking it. I will try to get more info with measurements and see what else I can offer for specs.
Thanks,
schemer


----------



## Technical Ted (Sep 30, 2017)

I suggest you use your scale and count how many threads there are per inch in your faceplate. You've got a pretty big bore and if it is 8 TPI you should easily be able to count 8 threads per inch on your scale or, in other words, one thread per 1/8" division on your scale. From what you are saying, it sounds like it's not actually 8 TPI. Thread gauges are very nice, but using a scale as I've described, especially on a very large, coarse thread like this, should be fairly easy and accurate. 

Good luck,
Ted


----------



## schemer (Sep 30, 2017)

Technical Ted said:


> I suggest you use your scale and count how many threads there are per inch in your faceplate. You've got a pretty big bore and if it is 8 TPI you should easily be able to count 8 threads per inch on your scale or, in other words, one thread per 1/8" division on your scale. From what you are saying, it sounds like it's not actually 8 TPI. Thread gauges are very nice, but using a scale as I've described, especially on a very large, coarse thread like this, should be fairly easy and accurate.
> 
> Good luck,
> Ted



I will do that tomorrow when I get back out in the workshop. I did try to measure yesterday with the scale when I first ran into this problem on my first attempt on making the adapter (didn't look as good as I would have liked with rough thread) and it seemed close, but I will check more carefully and accurately. Will report back tomorrow.
Thanks,
schemer


----------



## Silverbullet (Oct 1, 2017)

Many are either 2 1/4 " -6 or 2 3/8" - 6 . One of the two south bend used for years in there lathes. Ck the threads with a thread pitch gage. Or count the tops of the threads per inch.


----------



## schemer (Oct 1, 2017)

Silverbullet said:


> Many are either 2 1/4 " -6 or 2 3/8" - 6 . One of the two south bend used for years in there lathes. Ck the threads with a thread pitch gage. Or count the tops of the threads per inch.



Man I was hoping you were right so I could sell this and buy another one. But I checked this morning and with a calipers the ID's are the same and with a 6 inch scale likewise. I put the 6 inch scale across the threads and they are right on at 1/8" apart on both. I will take some pics and post them here in case a sharper eye than mine can spot some obvious issue. Seems like a tap is going to be the best approach because if I sell it on ebay the buyer is going to have the same problem.


----------



## Wreck™Wreck (Oct 1, 2017)

If I understand your post correctly you have a lathe with a 2 1/4-8 threaded spindle nose.
You then turned a 2 1/4-8 plug gauge which works with a new internally threaded part yet not an old internally threaded face plate of the same thread?

Am I on the right track so far?


----------



## schemer (Oct 1, 2017)

Wreck™Wreck said:


> If I understand your post correctly you have a lathe with a 2 1/4-8 threaded spindle nose.
> You then turned a 2 1/4-8 plug gauge which works with a new internally threaded part yet not an old internally threaded face plate of the same thread?
> 
> Am I on the right track so far?



Yes, sort of. Except my lathe doesn't matter in this case as I am using the faceplate for a welding positioner but bought a 2 1/4 - 8 threaded faceplate and threaded backplate for the project. I bought the faceplate based on size of threads as advertised on ebay in October of 2016 and it has been sitting in a box since so I never had anything to test it with or any reason to doubt the threads. I have taken a few pics but my battery is on the charger at the moment. The two plates (backplate and faceplate) were bought and I just machined the male adapter to screw into them and one works, one does not.


----------



## Silverbullet (Oct 1, 2017)

One has to be wrong , I'm still thinking the ones a different thread . With threads that large it's hard to think it's the same number and not fitting unless something is wrong on the pitch.


----------



## schemer (Oct 1, 2017)

Silverbullet said:


> One has to be wrong , I'm still thinking the ones a different thread . With threads that large it's hard to think it's the same number and not fitting unless something is wrong on the pitch.



Well one thing for sure is one doesn't work. It will just screw in about 1/8 of a turn so really not even close. Here are some pics of the faceplate with a scale involved and some just to show the thread. They didn't make left handed threads on any of these did they>


----------



## Technical Ted (Oct 1, 2017)

From the angle of those pictures it sure looks like an 1/8" pitch. That leaves the major diameter. Do you have a way to measure that, like with a pair of old fashion internal calipers or something?

Also, are there any markings on the faceplate? Brand, manufacturer, anything?

From those pictures I wouldn't say those threads look damaged at all. The actually look like they are in very good shape. And they appear to be right hand.

Edit: One more thing... other than pitch and major diameter (pitch diameter really) are they are sharp V thread? For example, Whitworth are rounded and these may be common on lathes from the UK, I really don't know since I have no experience with them. But if it doesn't screw on there certainly is something off. 

So, we have correct thread style (thread form), correct pitch and correct pitch diameter. If those three things match up it should screw on. 

Ted


----------



## Technical Ted (Oct 1, 2017)

Sometimes it pays to put some dye, layout blue, Persian blue, Dykem or whatever (even use a black magic marker) on the thread and use this to help determine where the interference is.... this might give a clue.

Ted


----------



## schemer (Oct 1, 2017)

Technical Ted said:


> From the angle of those pictures it sure looks like an 1/8" pitch. That leaves the major diameter. Do you have a way to measure that, like with a pair of old fashion internal calipers or something?
> 
> Also, are there any markings on the faceplate? Brand, manufacturer, anything?
> 
> ...



I measured the ID on both the one that works and the one that is in the pics, that does not. I used a calipers and they were exact. The faceplate that doesn't work has "flat" threads as opposed to the one that does as it had sharp pointed threads. So I guess the caliper measurement could be off based on that. Maybe the one that works is oversized and has a sloppy thread and throw in my handy work of cutting the threaded adapter, it could all add up.  I haven't cut threads in a while and botched the first one as it had rough looking threads and was not symmetrical due to me screwing up somehow. The second one was better but still had rough looking threads but was symmetrical and the "V" shape. But both of my adapters screw into the one backplate just fine although maybe a little sloppy. Maybe my lack of expertise is all that is wrong here but I cut a 0.150 thou relief before cutting the threads and now that I think of it maybe it should have been 0.170 thou? The reason I say that is at the end of the cut where the adapter screwed on the tool was just starting to hit the relief area. My starting major diameter was 4 or 5 thou under 2.250. Anyhow, by the time this is all done, I will persevere.


----------



## schemer (Oct 1, 2017)

Technical Ted said:


> From the angle of those pictures it sure looks like an 1/8" pitch. That leaves the major diameter. Do you have a way to measure that, like with a pair of old fashion internal calipers or something?
> 
> Also, are there any markings on the faceplate? Brand, manufacturer, anything?
> 
> ...



No brand names or markings. Ebay special with description saying:
2 1/4" x 8 TPI 8 3/8" + dia. Slotted Faceplate for Southbend


----------



## schemer (Oct 1, 2017)

I used this threading tool to cut the threads:
http://www.ajaxtoolsupply.com/alaxa...MI6PLHvP_P1gIVC6J-Ch2xLwcfEAQYAiABEgLKgvD_BwE


----------



## schemer (Oct 1, 2017)

Technical Ted said:


> Sometimes it pays to put some dye, layout blue, Persian blue, Dykem or whatever (even use a black magic marker) on the thread and use this to help determine where the interference is.... this might give a clue.
> 
> Ted


I can surely give that a try but the interference is right away and may just show that. The backplate that I bought new from ebay has pointed sharp threads whereas the faceplate has a flat thread. That seems to be where the problem lies like maybe a different type of thread.


----------



## Technical Ted (Oct 1, 2017)

schemer said:


> I used this threading tool to cut the threads:
> http://www.ajaxtoolsupply.com/alaxa...MI6PLHvP_P1gIVC6J-Ch2xLwcfEAQYAiABEgLKgvD_BwE



That's a good ol' 60 degree V thread which is the most common in the USA. I'm more concerned with the thread in the face plate being that same type and at the proper pitch diameter.

Also, another thing to keep in mind, is that face plates can be purchased "blank" meaning no threads to mount on a spindle so the new owner can thread their own as desired. It is certainly possible that the previous owner threaded this himself and didn't take the thread to full depth for some reason... maybe he fitted it to an under size spindle??? Who knows. 

If it is the case where the threads just aren't deep enough, it could be put on a lathe, indicated in, and very carefully line up a internal single point threading tool on the original thread and then taken to depth. That is what I would do if I found myself in this situation. It sounds more difficult than it is if you've never done it before. You'd have a nice large bore and coarse thread to give you a big advantage over a much smaller bore. You run the threading tool in using your half nuts, stop the spindle while the tool is inside and then line the tool up in the thread using your compound and cross feed. Do this over and over a few times making very small adjustments until you just start to make a chip and then go from there. Doing this type of work is a great skill to have in your tool belt. Just go very slow and carefully. One additional word of advice is to make sure your threading tool has sufficient clearance because you will be inside a bore and you don't want it rubbing. 

Ted


----------



## schemer (Oct 1, 2017)

Technical Ted said:


> That's a good ol' 60 degree V thread which is the most common in the USA. I'm more concerned with the thread in the face plate being that same type and at the proper pitch diameter.
> 
> Also, another thing to keep in mind, is that face plates can be purchased "blank" meaning no threads to mount on a spindle so the new owner can thread their own as desired. It is certainly possible that the previous owner threaded this himself and didn't take the thread to full depth for some reason... maybe he fitted it to an under size spindle??? Who knows.
> 
> ...



I just learned that skill yesterday (chasing a thread) as I had something go wrong and I do not fully understand what happened. I don't think I backed out the cross slide enough after taking a bunch of compound cuts and when I moved the carriage to the right the tool bit hit each thread (like click click click click etc) but I just said oops (really said #&*!$@) and just went in for the next cut on the compound. It started to cut and then caught on something and moved the part in the chuck and made it wobble a little. I then said "#&*!$@" again and remembered something I read somewhere about if that happens..."don't worry as it's easy to fix". So I re -chucked the part and got it spinning true and engaged the half nut with the tool away from the part and then stopped the machine with the half nut engaged. I move the cross slide and compound until it looked right and finished the part. I was proud. I do plan on making one more of these adapters as the 3rd time is the charm, right?

I will see if that method above is something I want to tackle but first I am going to buy a few more tools like a Starrett thread gauge that has 8 TPI on it. My cheap set does not go that low. I have thread rods for measuring but didn't use them as I am going to need to practice with those first. I think grease would help or I need an extra hand.

But you are correct. The "who knows" factor is there and is just my luck. The good part is that I somewhat successfully cut the 2 1/4 - 8 TPI threads and they actually feel pretty good as far as fit. The finish, not so much. But when I make the 3rd one I will have experience.  And based on that "flat" spot on the entire thread on the faceplate that does not fit, it may be the problem all along that the cut is not deep enough.
Thanks,
schemer


----------



## Technical Ted (Oct 1, 2017)

Here's my advice on using thread measuring wires. No matter what you use (if anything) to help hold them in position clean your chip pan out first!!! Ask me how I know... I spent I don't know how long searching for one once. I did finally find it, but never again will I use them with a bunch of chips/shavings under where I'm measuring! 

I'm sure you'll get the hang of it. Keep your cutting tools sharp and use a good quality threading oil on steel. 

Good luck!
Ted


----------



## schemer (Oct 1, 2017)

Technical Ted said:


> Here's my advice on using thread measuring wires. No matter what you use (if anything) to help hold them in position clean your chip pan out first!!! Ask me how I know... I spent I don't know how long searching for one once. I did finally find it, but never again will I use them with a bunch of chips/shavings under where I'm measuring!
> 
> I'm sure you'll get the hang of it. Keep your cutting tools sharp and use a good quality threading oil on steel.
> 
> ...



Thanks for all the help. I will let you know what happens when I get it done. I ordered a used Starrett thread gauge on ebay for future reference that goes to the lower TPI range although it will probably be rare to use/need it after this. I need to get a thread mic too. On the cutting/threading oil I have been using that sulphur smoking stuff from Lowes and Home Depot:
http://www.homedepot.com/p/Oatey-16-oz-Dark-Thread-Cutting-Oil-302032/203461243
But I have others. I even bought some of that Boeshield paste: http://orelube.com/products/paste/ but I haven't tried it yet. I have others too but used what was handy. What is a good tried and true thread cutting oil. I have lard and can mix it with mineral oil but just recently read about that but haven't tried it yet. Seems I read 60/40 with the lard and mineral oil. And the threads I have cut in the past I did fine but they were like 1/2 or 3/8 and this project was on unknown steel I bought from ebay. I know one thing for sure it isn't 12L13 or 12L14.  I just looked it up and it is DOM tubing so most likely 1020 or 1026 steel so I guess seeing it turns fine it should thread fine too. At least I know it will be weldable.


----------



## jerrythepilot (Oct 1, 2017)

You could try wrapping the male thread with a tight wrap of teflon tape. Turn it into the other plate that it goes into, turn it back out and look at the tape. Then remove the tape and wrap it with a new piece, and try it in the one that won't go in. Turn it back out and look at the tape. If it is shredded at the points of the thread then I would think that the female thread isn't deep enough. If it goes on furtherthan before, then maybe you do need some lubricant on the threads.

Jerry


----------



## Technical Ted (Oct 2, 2017)

schemer said:


> Thanks for all the help. I will let you know what happens when I get it done. I ordered a used Starrett thread gauge on ebay for future reference that goes to the lower TPI range although it will probably be rare to use/need it after this. I need to get a thread mic too. On the cutting/threading oil I have been using that sulphur smoking stuff from Lowes and Home Depot:
> http://www.homedepot.com/p/Oatey-16-oz-Dark-Thread-Cutting-Oil-302032/203461243
> But I have others. I even bought some of that Boeshield paste: http://orelube.com/products/paste/ but I haven't tried it yet. I have others too but used what was handy. What is a good tried and true thread cutting oil. I have lard and can mix it with mineral oil but just recently read about that but haven't tried it yet. Seems I read 60/40 with the lard and mineral oil. And the threads I have cut in the past I did fine but they were like 1/2 or 3/8 and this project was on unknown steel I bought from ebay. I know one thing for sure it isn't 12L13 or 12L14.  I just looked it up and it is DOM tubing so most likely 1020 or 1026 steel so I guess seeing it turns fine it should thread fine too. At least I know it will be weldable.



There are a lot of synthetics out there that I'm sure are very good, but I just use the good ol' sulfur smoking stuff. I bought a can of Rigid pipe threading cutting oil years ago and still use that. I use it for tapping, threading and whenever I want a nice finish cut on steel (99% of the time I use HSS cutting tools). 

That lard and mineral oil thing is a little dated. Be careful because the lard can become rancid. Never tried it myself and probably never will. 

Good luck and have fun,
Ted


----------



## schemer (Oct 2, 2017)

jerrythepilot said:


> You could try wrapping the male thread with a tight wrap of teflon tape. Turn it into the other plate that it goes into, turn it back out and look at the tape. Then remove the tape and wrap it with a new piece, and try it in the one that won't go in. Turn it back out and look at the tape. If it is shredded at the points of the thread then I would think that the female thread isn't deep enough. If it goes on furtherthan before, then maybe you do need some lubricant on the threads.
> 
> Jerry



The part won't even barely start on the one it doesn't fit on so the teflon tape test won't work I'm afraid. And lube is not the issue. I am pretty sure though the thread on the faceplate is just not cut deep enough. I found a tap on ebay and made a best offer and got a deal on it. The way I see it I can use the tap, fix the problem (hopefully), and sell the tap on ebay and break even.


----------



## schemer (Oct 2, 2017)

Technical Ted said:


> There are a lot of synthetics out there that I'm sure are very good, but I just use the good ol' sulfur smoking stuff. I bought a can of Rigid pipe threading cutting oil years ago and still use that. I use it for tapping, threading and whenever I want a nice finish cut on steel (99% of the time I use HSS cutting tools).
> 
> That lard and mineral oil thing is a little dated. Be careful because the lard can become rancid. Never tried it myself and probably never will.
> 
> ...



Ted,
  I found a tap on ebay, made an offer, and got it! So I will try that first in the hope that it isn't cut deep enough. If the tap fixes it, I can sell the tap on ebay and get my money back. If it doesn't work, I will be ready to attempt the thread chasing trick. 

I figured lard would go rancid but never tried it. I use HSS 99% of the time too. I just don't do as much threading on the lathe but do tap holes a lot normally with manual tap handles. Always wanted to get a TapMagic or whatever they call those tapping heads but they aren't cheap.


----------



## Technical Ted (Oct 2, 2017)

Well, I would say that the tap will fix the problem regardless of what the real issue is! 

Please let us know how everything turns out for you.

Ted


----------



## Silverbullet (Oct 2, 2017)

Is there anyway the relief cut in back isn't large enough to fit the lathe boss or register it's called. If it's tight there it won't allow the threads to work . Try dykem on the inside before the threads .  It may be there's not enough to allow the threads to enter. It looks like it's exact size to the pitch no room to move. Try spinning it on backwards .


----------



## schemer (Oct 2, 2017)

Technical Ted said:


> Well, I would say that the tap will fix the problem regardless of what the real issue is!
> 
> Please let us know how everything turns out for you.
> 
> Ted



Yeah, it better!


----------



## schemer (Oct 2, 2017)

Silverbullet said:


> Is there anyway the relief cut in back isn't large enough to fit the lathe boss or register it's called. If it's tight there it won't allow the threads to work . Try dykem on the inside before the threads .  It may be there's not enough to allow the threads to enter. It looks like it's exact size to the pitch no room to move. Try spinning it on backwards .



Good thought. I didn't think of that as it doesn't screw on from either side and I assumed it was factory made for South Bend and should be perfect. But if someone else (or even the factory) didn't do that correct you would think there would be tool marks past the threaded area. On the back side anyway. But the adapter does contact the threads from either side but only turns at most 1/8 of a turn (like from 9 to 10 on a clock). I will give it a good look at though.


----------



## schemer (Oct 20, 2017)

Just a followup. I ran the tape through the two adapters and my part only fit the first one so I guess the foirst one was cut sloppy. So I a tooled up and ready to make a new piece and do it right this time.


----------

