Need advice to clean up a MT2 socket

[Gard]

Here is what I have tried. The inside of the 1940s south bend 10L lathe tailstock spindle was all chewed up. I have several MT2 reamers, not sure where they all came from, one was a set from Grizzley (india) roughing and finishing set, others from boxes of tools from classified ads. I grabbed a reamer with an adjustable wrench in one hand and the spindle in the other. This did not seem to do anything so I mounted the spindle in a chuck of a different lathe at about 200 rpm and pushed the roughing reamer in with the tailstock, still holding it with an adjustable wrench so the reamer was sort of floating. Lubricated with oil and I backed off the force before turning off the lathe. Now I am cutting some metal. Clean and repeat with the finish reamer. The bore now looks much better probably 95% of the surface is cleaned up. Holding the adjustable wrench seemed a little sketchy, this going to hurt if the reamer grabs.
I clean it using a lint free cloth wraped around a brisle brush, add a thin line of blueing to the test bar, insert and twist 1 revolution. Blueing now shows contact along the length of the test bar taper but there are a couple spots where there is a circumferential scratch on the taper bar. A loup shows a small defect in the reamer at about this spot. I lightly polish the test bar with a hard fine stone and try a different finish reamer with similar results. I feel like I am missing something. What is best practice for using a reamer or is that even the best tool? I notice different finish reamers seem to remove metal from different areas of the bore. Perhaps I should dig out the bore scope to get a look down inside there. I have used spring loaded hones to clean up brake cylinder bores and engine culinders but do not have one this small.


This last photo is an attempt to show the outside diameter of the cutting edge in the suspect area.

 

[metalmagpie]

Uh, shouldn't you be using 3MT reamers?

 

[steve-l]

You do not have to remove low spots. It is not necessary and adds no value, The reamer is the correct tool unless you are prepared to regrind the spindle taper. A blue check is more than enough. Just knock off the high spots.

 

[JST]

Uh, shouldn't you be using 3MT reamers?

"Here is what I have tried. The inside of the 1940s south bend 10L lathe tailstock spindle was all chewed up. I have several MT2 reamers, not sure......."

10" have MT2 T/S.

The only issue with a reamer is that it is not "guided", so you have no particular guarantee of correct orientation. For just cleaning up a taper bore, that is much less of an issue.

 

[Gard]

I understand the reamer will follow the existing hole. My question is more about technique, I guess I should be able to use the MT2 reamer turning it by hand with a tap wrench and some amount of downward force with lots of light oil, perhaps something like wd40? I have heard to never turn it backwards. One place said stop rotation and pull straight out. Any other tricks of the trade? I think I can see a small raised spot in there with a bore scope but sometimes it is hard to tell between a raised bump and low diviot under magnification. I am thinking if there is a raised bump after most of the bore is cleaned up, it must be a bad reamer and I should I should try the other 2 finish reamers and see if I can find one that works better. Other possibilities are my technique is flawed and leaving a goober in there or the goober has always been in there and it is so hard that it is ruining my reamers?
The photo of the blued up test bar is not the best but there is 1 or 2 small scratches that go around the test bar.

 

[jwearing]

You'll lose concentricity pretty fast with a hand-reamer. Especially with the single-handled wrench, the two-sided wrench is a little better. When touching up a spindle/quill like this you really just want a delicate touch, just remove the burrs and raised spots. If I remember correctly, the spec on concentricity for this is .0005"/12".

Does your lathe have a taper attachment?

I tried something similar with mine, gave up on it because I couldn't hold the spec. I'm waiting to try again until my lathe with taper attachment is running.

 

[Gard]

I do have a taper attachment and I was relatively successful at reboring a drill press Mt2 spindle taper. The challenge I found with that case was getting the spindle spindle both concentric and parallel to the axis of the bearings. With the tailstock I do not think there is much of a concern that the socket is concentric, it just needs to be parallel in horizontal and vertical to the lathe bed. I admit this is kind of a minor distinction with little practical value.
The concern I have with the tailstock is that taking even a small enough amount off the inside diameter with a boring bar will set the male end way further back in the sockett. This will reduce the travel of the tailstock before the tool is ejected. This tailstock has only 2" of travel to begin with.

When I put bluing on the test bar and rotate it in the socket the blueing is uniformly distributed around the length and diameter of the test bar with the scratch seen in the photo. When I look inside the socket there is no bluing at the bottom 1 inch of the hole on the top side even though it is an area that was recently cut by the reamer. I think this tends to confirm it is a raised spot I am seeing which is aligned to the nick in the reamers. I may try to clean it up with a stone or scraper before going at it with my last most pristine reamer. Perhaps now is the time to build some kind of tool post grinder that will reach down in there?

 

[Bakafish]

Yeah, you may have some bit of embedded hardened swarf down there. I had some adventures with a Hitachi MT2 hand drill that used a hardened shank. Someone had spun a bit in there and managed to create some tiny concentric ridges, and those had cause the next bit they used to permanently lock itself into the taper. After a prolonged battle getting it removed, the CN reamers I tried couldn't even begin to cut the hardened surface. I ended up having to use a (admittedly rare) carbide taper scraper to remove them, and it worked great after that. There are hardened Cobalt taper reamers available, but they were several times the cost of the drill.

I'd also note that if the main concern is that damaged taper is ruining your tooling, there are high quality MT2 'drill extenders' that could be used as a sacrificial unit, you could semi-permanently mount it in the damaged taper and use its fresh taper for your tooling.

 

[Gard]

Yeah, you may have some bit of embedded hardened swarf down there. I had some adventures with a Hitachi MT2 hand drill that used a hardened shank. Someone had spun a bit in there and managed to create some tiny concentric ridges, and those had cause the next bit they used to permanently lock itself into the taper. After a prolonged battle getting it removed, the CN reamers I tried couldn't even begin to cut the hardened surface. I ended up having to use a (admittedly rare) carbide taper scraper to remove them, and it worked great after that. There are hardened Cobalt taper reamers available, but they were several times the cost of the drill.

I'd also note that if the main concern is that damaged taper is ruining your tooling, there are high quality MT2 'drill extenders' that could be used as a sacrificial unit, you could semi-permanently mount it in the damaged taper and use its fresh taper for your tooling.

Very interesting, what is a CN reamer? How does a carbide taper scraper work and what does it look like? Is it possible to scrape a taper for alignment?
I am at the stage now in rebuilding this lathe to try to get the tailstock spindle as good as I can reasonably get it. A new spindle may be in order at some point in the future.

 

[Bakafish]

Very interesting, what is a CN reamer? How does a carbide taper scraper work and what does it look like?

This is a side view. It is shaped like a babbitt scraper, but made out of carbide.

Is it possible to scrape a taper for alignment?

I suppose it is possible, but you would need to constrain the two tapers when transferring the bluing compound between them. It would be a big challenge, you would be better off just grinding it. This is really more for removing galled spots or ridges and improving contact area. I think they are quite rare though.

I am at the stage now in rebuilding this lathe to try to get the tailstock spindle as good as I can reasonably get it. A new spindle may be in order at some point in the future.

I don't know that 'spindle' is the right term for that, I believe it is called the barrel. And honestly as long as it isn't slipping or damaging your tooling, the tailstock itself should be able to adjust a lot of the error out of it. It's easy to obsess on this stuff, but just get it working and look for lower hanging fruit.

 

[Gard]

This is a side view. It is shaped like a babbitt scraper, but made out of carbide.

View attachment 389153

Thanks for the photo, that is a large chunk of carbide, I guess it would be rare. I googled babbit scraping to get some idea of how it works. I think I will call it good enough for now, I can always go back and work on it more later if it causes a problem.

 

[Bakafish]

Thanks for the photo, that is a large chunk of carbide, I guess it would be rare. I googled babbit scraping to get some idea of how it works. I think I will call it good enough for now, I can always go back and work on it more later if it causes a problem.

That's a picture of the large sized one I had handy, I actually picked up two sizes when I recognized them at auction, the smaller one is a better fit for MT2.

The bluing you showed looked like there was plenty of contact. Better to leave it alone as long as the hard spot isn't damaging your tools. I wouldn't be surprised if there are replacements available or that you could make or have made a nice replacement if it really becomes a problem.

 

[Gard]

So I guess you are using the engraving burr on something like a Dremel tool? I had thought about using a small grinding wheel on a dremel.
I am ordering some 4" long 1/2" diameter round stones to try. The riffler file seems like a good idea, have not tried that. This is MT2 so my fat fingers can only reach a small way in there and its hard to see with light and magnifiers.

I think there is a potential to damage tools. I guess the damage would be minimal if the tool did not spin. From a practical standpoint I like the idea of using a taper extension.. The first photo shows the test bar I have been using with blueing, I put a lengthwise smear of blueing on it, insert it with light force and did a complete revolution and remove to look at the blueing on the test bar and socket (photo in my first post). After cleaning off the blueing you can see the circumferential scratches. By this point I had done several cycles with the test bar so not sure which one caused the damage.

I had been using a small bristle brush wrapped with a lint free cloth to clean the taper. Not sure if that was getting everything so I turned down a block of hardwood to a MT2 taper, I have tried it by itself and wrapped with cloth to clean the socket. This seems a little more positive but open to suggestions on how to clean a taper socket especially if it is in a machine.This tailstock spindle (aka quill or barrel) is out of the tailstock so perhaps I should be flushing with solvent.

I took a new, never used MT2 tool holder. I tried to add blueing but the blueing sort of beaded up on the surface of this one, not sure what that is about. Anyway this time I inserted the tool and rotated it only about +/- 10 degrees, marked the location and removed it. There are now several circumferential scratches all about 1/4" long so there must still be goobers in there and I have an idea of where they are. I suspect that the goobers may be harder than the parent material just due to work hardening? I previously removed some from the head stock spindle bearing surface and that was challenging enough to stone off just the high spots when I could see what I was doing.

I realize I am spending more time on this than may be justified but I am looking at it as a learning experience for machine reconditioning skills, certainty not competing with paying work but an interesting challenge.

 

[John Garner]

The cylindrical piece of a tailstock assembly that slides to and fro while holding a tool-or-tooling arbor has, in U S English, several names. "Spindle" is probably the most common, but "quill" and "ram" are frequently used.

The spindle/quill/ram is guided as it slides by the tailstock "barrel", "bore", or less commonly "guide".
I've also heard Some the term "barrel" to mean the tailstock component that contains the "bore".

I haven't a clue if or how these terms are used in other countries' English.

 

[Bakafish]

From a practical standpoint I like the idea of using a taper extension.

Yeah, that's what I suggested. At some point it appears that swarf got in that taper and embedded itself in the bore. The simplest solution is just to get an MT2 drill extension, or an MT3 to MT2 adaptor and semi-permanantly mount it, using the fresh taper it provides to ensure your tooling doesn't become further damaged.

A hardened, Japanese made "Globe" MT2 to MT2 extension is about $80 here in Japan. I've seen the CN units for about $30, I spent the money on the good one though. Being hardened and not reinserting it all the time will ensure it has limited damage from the existing taper, and make it a good investment long term, even if you replace the barrel at some point.