# Pm1440GT one piece spindle bore dead center



## Lonewolfgun (Dec 4, 2020)

So I bought a MT5 spindle bore the other day and when it arrived today it doesn't fit, too small. SO I grab my manual and it says MT5 on it. So I go to PM's website to check the specs on there and too my surprise it says MT5-1/2.

So I did a quick google search to see if I can find a one piece dead center and I don't know if my google-fu isn't strong today or there isn't much out there on a mt5-1/2.

Does anyone know where to find a one piece MT5-1/2 that'll fit the spindle bore?


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## mksj (Dec 4, 2020)

You should have a "Reducing Sleeve for Headstock Center" that came with your lathe in the toolbox, you will need to check if it is a MT4 or 3.


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## NortonDommi (Dec 4, 2020)

I would measure the taper.  I have a similar sized Chinese import machine and it has a MT6 headstock taper. 
I have on occasion heard Morse Stub Tapers referred to as 1/2 sizes but best to measure and be sure.  typos are very common these days.
BTW the only 1/2 size is a MT 4 1/2 which is is pretty much obsolete.


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## Lonewolfgun (Dec 4, 2020)

There is a reducing sleeve in there but there isn't anything written on it.

I know it's not a mt6 because the BV I had was a MT6 and the dead center I kept from it is considerably bigger.


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## Jim F (Dec 4, 2020)

Maybe email PM and ask them for the dimensions of the new MT taper they made ?


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## mksj (Dec 4, 2020)

The 1440GT headstock spindle taper is a MT 5 1/2, it is unusual but it is a function of the D1-5 mount and the 2" spindle bore. You can measure the taper on the reducing sleeve, I expect it is a MT4 but you can ask them if you are unsure. Many lathes come with a reducing sleeve for the headstock spindle taper. It is probably possible to recut the taper on a MT6 dead center, may be difficult to get it spot on. I have cut ER collet tapers and MT3.


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## dpb (Dec 4, 2020)

My 1440gt’s reducing taper is MT5.5 to MT3.


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## NortonDommi (Dec 5, 2020)

So the Taiwanese have invented an MT 5 1/2? The MT tapers go from 0 - 7 with the only half size 4 1/2.   I would measure the actual taper and be certain.  I would also seek confirmation from PM.


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## dpb (Dec 5, 2020)

Perhaps MT5.5 is incorrect terminology, but it is the terminology PM uses.  MT5 is too small, MT6 too big.


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## erikmannie (Dec 5, 2020)

I am in a very similar situation. I have every reason to believe that the internal taper of the spindle nose on my PM-1660TL with a D1-6 Camlock is 6 1/2 Morse Taper (!).

The only solution I found is make my own dead center. The material (cold rolled steel) was only $66.


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## NortonDommi (Dec 5, 2020)

Lonewolfgun said:


> I know it's not a MT 6 because the BV I had was a MT 6 and the dead center I kept from it is considerably bigger.


So you bought a MT 5 and it is too small, a MT 6 is too big and PM state that the taper is a MT 5.5 which is not a thing as far as any listings anywhere that I am aware of but then I know only what is listed by some sources.  Apparently grade 9 bolts are a thing now too.
  If you are going to make one you will still need to accurately measure what you have. A MT 5 would not pass 2". IF some taper has been made and called a MT 5 1/2 is it a 'stub' taper?  Regardless it would be nice to know and think how many people you could help!  A MT 4 1/2 & a MT 7 are the only ones with the same taper so there is no way out of measuring it.
  At least then you will be able to compare your measurements with all known standard tapers.


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## Tozguy (Dec 5, 2020)

Jim F said:


> Maybe email PM and ask them for the dimensions of the new MT taper they made ?


Please let us know if someone finds 'official' dimensions for an MT5 1/2. 
It would also be interesting to know if this taper shows up on other brands besides PM.


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## Lonewolfgun (Dec 5, 2020)

I sent Precision Matthews  a message to find out more info on this taper.


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## mksj (Dec 5, 2020)

It really doesn't matter what the internal taper of the spindle is, all these lathes come with an adapter for a spindle adapter for the spindle to use a dead center, on the 1440GT per above it is a MT3, on the TL series it is a MT4. They also should have come with dead centers in the tool box. If you read the manual and the description they describe this. No need for fairy dust to determine the sizes.

The 1440GT Manual States:
*Spindle:*
_*Chuck/faceplate attachment D1-5 Camlock
Internal taper MT5-1/2*_

TL manual states that the spindle is a MT6 and the  site description states:
*Spindle:*

*Spindle Mount D1-6 Camlock Quick Change*
_*Internal taper of Spindle is a MT 6 (With included reducing sleeve) MT 4*_
*Spindle bore 2.55” in. diameter (will pass a 2.500″ piece)*


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## erikmannie (Dec 5, 2020)

Lonewolfgun said:


> I sent Precision Matthews  a message to find out more info on this taper.



If you ever do make your own (“one piece”as in the title of this thread) dead center (the tail of which will have the same outer dimensions as your reducing sleeve), you can tell when you have the taper angle cut perfectly as follows:

Imagine two (very clean!) identical reducing sleeves laying up against each other, but facing different directions. The sides farthest away from each other will now be truly parallel, and you could measure this accurately with an outside micrometer.

I was measuring my tapered sleeve, and I used dial calipers. An outside BLADE micrometer would have been better. If and when you do you like the above (and have two identically tapered shafts up against each other facing different directions), you can use a standard outside micrometer.


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## erikmannie (Dec 5, 2020)

mksj said:


> It really doesn't matter what the internal taper of the spindle is, all these lathes come with an adapter for a spindle adapter for the spindle to use a dead center, on the 1440GT per above it is a MT3, on the TL series it is a MT4. They also should have come with dead centers in the tool box. If you read the manual and the description they describe this. No need for fairy dust to determine the sizes.
> 
> The 1440GT Manual States:
> *Spindle:*
> ...



Oh, I get it now. The spindle bore of a TL, being a straight 2.55”, will pass a 2.500” piece. The spindle NOSE, however, has an MT6 taper. Looking at the dimensions below, it looks like an MT6 taper cannot pass a 2.500” piece:







I have a 1660TL and I can pass a 2.500” piece through the (tapered) nose spindle of the D1-6 camlock mount. If I were to buy an MT6 dead center, I would be able to pass this dead center all the way through the spindle (spindle nose and all) and out the other side.

Maybe a good product idea for PM is to offer “one piece” dead centers that have the same tail dimensions as the reducing sleeves, but extend out to a 60° tip. Never mind the fact that the diameter of such a dead center would not pass through many of the center holes in the chucks that we use.

The pass through diameter is one of the big selling points of a lathe, but if the smallest diameter of a dead center must be greater than this pass through diameter (explanation below), the taper on the dead center makes for a diameter that is even larger where the dead center is to pass through the center hole of the chuck in use. None of the center holes in my chucks are big enough for that. Such a dead center would also stick out very far! When you use the reducing sleeves that PM provides, the tip of the dead center ends up right where you would want it.

In order for the paragraph above to make sense, you have to understand that the reducing sleeve bottoms out when you put it in (or at least this is the case with my 1660TL and D1-6 camlock). I.e., the internal diameter of the spindle nose taper is at all points larger than the diameter of the straight walled spindle. This is not advantageous if you’re trying to use an off-the-shelf dead center. 

The reducing sleeve is critical if you want to use a dead center at the headstock end!


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## Tozguy (Dec 5, 2020)

Lonewolfgun said:


> Does anyone know where to find a one piece MT5-1/2 that'll fit the spindle bore?


Not so far it seems.
A more common approach would be to buy a center that fits in the adapter sleeve that was provided with the lathe (as already mentioned above). Since standard procedure is to skim turn a fresh point on the center everytime it goes in the headstock then it should not be made of hardened steel.
Solid centers dedicated for use in the tailstock are often hardened or have a carbide point so you have to keep them well identified.
BTW technically a live center is one that revolves with the work. A dead center is one that does not revolve with the work. So a solid center in the headstock would be a live center. But that does not prevent many of us from thinking otherwise.


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## erikmannie (Dec 5, 2020)

Maybe the OP is looking for something like this. This is currently for sale on eBay (title is  Morse Taper 7 MT7 Heavy Duty Dead Center for Lathe), but the dimensions are wrong for the OP.

Note how it is stubby and the tip has been reduced so that it will get through the center hole of most chucks.





Compare that profile to a dead center in a reducing sleeve:


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## NortonDommi (Dec 5, 2020)

mksj said:


> It really doesn't matter what the internal taper of the spindle is, all these lathes come with an adapter for a spindle adapter for the spindle to use a dead center





mksj said:


> No need for fairy dust to determine the sizes.


Absolutely a great need for "Fairy Dust" to be sprinkled upon this matter.
It absolutely matters what taper is in a lathes headstock as it is not just a LIVE centre that may be fitted, a collet holder immediately comes to mind as one such.  Nice to know if you wanted to fit a boring head for milling as well.
  Without knowing for certain what the taper is one cannot source or make something that will fit properly.  What happens when the reducer/adaptor sleeve is misplaced/lost/damaged?  This is the reason that there are for sale items that use other tapers than Morse.


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## mksj (Dec 5, 2020)

You have a spindle adapter that fits a standard dead center, that was the question, and that is the answer to this thread. I see no other question of fitting anything else. Almost every new lathe in this size comes with these types of adapters. If you want to fit something else like a 5C collet closure, that is different story, but that was not the question. The spec's on the PM lathes are spelled out in the site description and the manual,  might be worth reading the manual if you do not believe that it is a MT 5 1/2, if you need the dimensions to make an adapter then measure it.


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## Tozguy (Dec 5, 2020)

I do not question what PM says. But calling it a Morse taper leads me to think it has specific dimensions. If so I want them even if I don't need them.
If I had one to measure how would I know if it was a MT5 1/2 without having to rely on PM? 
Or is it a proprietary taper used only by PM?


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## NortonDommi (Dec 5, 2020)

mksj said:


> You have a spindle adapter that fits a standard dead center, that was the question, and that is the answer to this thread. I see no other question of fitting anything else. Almost every new lathe in this size comes with these types of adapters. If you want to fit something else like a 5C collet closure, that is different story, but that was not the question. The spec's on the PM lathes are spelled out in the site description and the manual, might be worth reading the manual if you do not believe that it is a MT 5 1/2, if you need the dimensions to make an adapter then measure it.


Actually the question was:


Lonewolfgun said:


> Does anyone know where to find a one piece MT5-1/2 that'll fit the spindle bore?


As far as I know there is no listing of a "MT 5.5 taper" anywhere but on the PM site dealing with this particular lathe.
IF no-one else in history has ever had, heard of, or listed a piece of machinery with a "MT 5.5 taper" the probability is that it is some weird taper that has been recently devised, not a Morse taper and has just labelled a "MT 5.5 taper" by some advert writer. 
  The argument that "Almost every new lathe in this size comes with these types of adapters." is spurious.  How many times has there been a post made by someone who has bought a, new to them, lathe and found the adaptor/sleeve missing and wanting to know if anyone knows where one may be purchased?  Quite a few over the years.
  At the end of the day the headstock taper in question is not a standard Morse taper.  Short of a drawing and measurements from PM,(which may be coming),measurement is the only option. 
  I have a MT 6 taper in my headstock and this means I can buy centres, adaptor sleeves, collet holders, odd arbours etc off the shelf just about anywhere in the known world.  Very handy having standards that the whole world agrees on.
  It looks as if buying sleeves may be an issue.  To this end I repeat that without measurement there is absolutely no way whatsoever to know what that taper is *especially* as it seems to be a non-standard unknown one that has been labelled a MT 5 1/2.
  As I have previously stated grade 9 bolts are now apparently a,[propriety],thing and it seems that a new class is being put aside for them.
  If the is such a thing as an international standard MT 5 1/2 taper please supply the documentation or links to such as I would love to know and would like to stick the specs in my library for reference plus it is Sunday and I always like to learn new things on Sunday.


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## erikmannie (Dec 5, 2020)

I think that there is a market among PM customers for longer blanks that fit in these spindle noses. Both the OP and myself have expressed an interest in a one piece dead center that fits in the taper. Again, not that there is anything wrong with using a smaller dead center in the reducing sleeve.

Alternatively, one could buy a spare adapter sleeve from PM, and then weld or braze in a similar material. For example, bore the sleeve’s internal taper to be straight, press in a custom “tip” which is a shaft machined on to round bar stock, braze or weld, and then cut the tip just like you want it. That would be a one piece dead center!

Obviously if you chose to braze it, you would not press in the stub shaft.


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## erikmannie (Dec 5, 2020)

The question marks in the title of this eBay auction indicate that the Seller is unaware of the exact specifications for the outside taper of the sleeve. More info in next post.


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## erikmannie (Dec 5, 2020)

This is a screenshot from the item description for the adapter sleeve pictured above:






Hmmm...”L and D1 spindled lathes”. No mention of Morse taper. This makes me wonder what the exact specifications are for the internal taper of a D1 (as in “D1-5 or D1-6 camlock”) spindle nose.

Maybe a D1-5 has an MT5, and a D1-6 has an MT6?


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## erikmannie (Dec 5, 2020)

At the risk of getting away from the original question, this company appears to sell “off the shelf” Morse taper reduction sleeves for spindles:









						The 6830 vise in MTD CNC - Bison
					






					www.bison-bial.com
				




See also:






						Morse Taper Sleeves
					

Pass-through reduction sleeve are for morse taper with thread. Some sleeves have flattening for easier remove from holder.




					toolsmach.com


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## Jim F (Dec 5, 2020)

mksj said:


> It really doesn't matter what the internal taper of the spindle is, all these lathes come with an adapter for a spindle adapter for the spindle to use a dead center, on the 1440GT per above it is a MT3, on the TL series it is a MT4. They also should have come with dead centers in the tool box. If you read the manual and the description they describe this. No need for fairy dust to determine the sizes.
> 
> The 1440GT Manual States:
> *Spindle:*
> ...


There is no such taper as a MT 5 1/2 listed anywhere , except with PM........


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## erikmannie (Dec 6, 2020)

Here is a long, wandering video about a guy with a mystery taper:


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## erikmannie (Dec 6, 2020)

And another video of a gentleman with a mystery taper:


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## erikmannie (Dec 6, 2020)

Sorry to keep posting YouTube video links, but these 2 are so pertinent to this thread:






and


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## erikmannie (Dec 6, 2020)

This might be a longshot, but this might be exactly what the OP is looking for:









						Metal Lathe Spindle Taper Adapter Center ? Morse Taper 6? D1-6 L-0 ?   | eBay
					

Unknown taper could be for Morse Taper 6?. D1-6 L-0 ?. Condition is Used.



					www.ebay.com


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## Lonewolfgun (Dec 7, 2020)

Received a response from PM

Hi XXXXXXXXX,
I haven't heard of it either, but there it is. They should have provided a reducing sleeve so that you could use a smaller taper in the spindle. You could use that to determine the actual size and the amount of taper.

Not very encouraging when the manufacturer hasn't heard of it either.


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## erikmannie (Dec 7, 2020)

Here is another longshot for the OP to buy a spare sleeve on eBay. I happened to know that the seller will accept an offer of $55.









						Lathe Morse Taper Adapter Tail Stock and Dead Center - New  | eBay
					

Find many great new & used options and get the best deals for Lathe Morse Taper Adapter Tail Stock and Dead Center - New at the best online prices at eBay! Free shipping for many products!



					www.ebay.com


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## erikmannie (Dec 7, 2020)

Lonewolfgun said:


> Received a response from PM
> 
> Hi XXXXXXXXX,
> I haven't heard of it either, but there it is. They should have provided a reducing sleeve so that you could use a smaller taper in the spindle. You could use that to determine the actual size and the amount of taper.
> ...



So there it is, then. I am in the exact same position as you, except with a Morse Taper 6 1/2 sleeve for my PM-1660TL lathe.

Having the sleeve on hand, it is entirely doable to take dimensions from that and make whatever you want. I bought round stock of C1018 (12” long, 3” diameter for $66) and 4140 (10” long, 4” diameter for $81) to make a couple of dead centers.

There are countless YouTube videos on how to do this. It does not look difficult. You use your existing sleeve to determine the change in radius over a known length. Then you use a dial indicator to cut that taper on your raw stock (definitely sneaking up on the angle!).

As long as you don’t overshoot the angle, you can even get away with cutting the diameter down too much. This is because you can part off the new dead center where the diameter is the same as the minimum diameter on your sleeve. The front will be cut to a 60° tip. I wonder if that would fit through the center hole in your chuck or a face plate. Mine won’t. Mine will have to have a reduced diameter tip to fit through my chucks & face plate.

You might want to either make one or obtain a spare sleeve now because if you do happen to misplace your sleeve, you will only be able to use a straight shank dead center in a chuck. It would also be considerably more difficult to re-cut the MT 5 1/2 taper without an existing taper on hand to copy.


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