# MT5 to 5C Taper Adapter



## Ray C (Nov 7, 2013)

OK, I needed to make myself another MT5 to 5C taper adapter and another member needed one as well so here it is.  Very easy to make but it's best if you draw it out first.

Here's a cross-sectional view as well as the dimensions for a spindle that has 1.5" diameter bore at the mouth.  These dimensions won't work in a PM1236 machine.  The adapters are custom sized depending on your spindle bore diameter.  The MT5 angle is the same but the overall dimensions are different.

View attachment MT5_5C_Adapter-dims.pdf

View attachment MT5_5C_Adapter-sv.pdf


The one I made is slightly different than the drawn plans because the piece of stock I had on-hand was slightly less in diameter than what I thought.  Also, I made the collar a little bit wider.  These are inconsequential modifications.  It's made of 1045 and I'll heat treat it this weekend.  Here's a play-by-play:

First, the outer OD was turned to maximum size.  This one is just shy of the 1.8" I planned to make it since the starting shaft was 1.75".  I just made one pass on the outside to get the scale off.  Not show here but, I bored a 1" hole down the center then did a precision bore to 1.260".  The maximum main shaft dimension of a 5C collet is 1.25" so I gave a little clearance.




Next, the compound was set for 10[SUP]o[/SUP] (corresponding to the 5C spec) and the inner taper was opened up to the spec show in the diagram (which I believe is 1.475").




After that, the compound was set to 1.5073[SUP]o[/SUP].  The angel was carefully set by using travel indicators and measuring rise over run.  The angle was then cut on the outside of the adapter.  I measured-off from the front of the adapter, where the taper should end.  In about 3-4 passes, the taper was cut from right to left.




Basically done... Just part it off.




And here's what it looks like...






I'll heat treat it this weekend.

Ray


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## pdentrem (Nov 7, 2013)

SWEET!
Pierre


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## Ray C (Nov 7, 2013)

Do realize that once you make one of these, all you need to do is thread an appropriately fitting tube to go through your spindle and make a collar nut -and bingo... You got your own 5C collet closer for about 15 bucks -instead of paying a couple hundred for a store-bought one.  I made one for myself but, I have this bad habit of using the metal for other projects and I can't find the other adapters or spindle tube.  I know I made one a while back...

I'll draw-up and post the dimensions for a PM1236 lathe sometime soon.


Ray


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## Ray C (Nov 8, 2013)

Here are the plans for an adapter that fits a Precision Matthews PM1236 lathe.  Since many companies have different bore diameter options this may or may-not fit on other 1236 lathes.

View attachment PM1236_Bore_MT5_5C_Adapter.pdf





Ray


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## itsme_Bernie (Nov 8, 2013)

Ray C said:


> OK, I needed to make myself another MT5 to 5C taper adapter and another member needed one as well so here it is.  Very easy to make but it's best if you draw it out first.
> 
> Here's a cross-sectional view as well as the dimensions for a spindle that has 1.5" diameter bore at the mouth.  These dimensions won't work in a PM1236 machine.  The adapters are custom sized depending on your spindle bore diameter.  The MT5 angle is the same but the overall dimensions are different.
> 
> ...



LOVE this.  I like to make anything that allows me to use 5C as much as possible!
Thanks Ray!  

Bernie


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## Ray C (Nov 8, 2013)

Thanks.  Glad you like it.

Do realize that the dimensions provided may not work on your lathe because there is no standard about the hole diameter in a spindle.  The only stipulation is the angle must match the MT5 spec (assuming of course, the spindle is MT5).  Since the bore diameter at the mouth of the opening could be different among lathes, you'll need to make an adapter for your particular spindle.

Anyhow... the drawings are provided to give you a feel for what's going on.

So, Bernie, are you going to make one?

LOL:  I found the pipe that I threaded from last time.  It was cut in half and I remember now, I used the other half on a temporary welding jig.  I also found the end nut.  That was intact...

Ray

PS:  The dimensions of the adapter for the PM1236 will allow you to use a full 1-1/8 collet and still have the ability to put a rod all the way through it.  Believe it or not, it took a few minutes of measuring and CAD work to get the dimensions right. 





itsme_Bernie said:


> LOVE this.  I like to make anything that allows me to use 5C as much as possible!
> Thanks Ray!
> 
> Bernie


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## buffdan (Nov 9, 2013)

Ray,
do you plan on doing any "touch up" after heat treating, like light pass with tool post grinder to 5C taper, or this should be finished product before/after heat treating? Any expectations of dimensional changes?

Thanks for all of your posts, very much appreciated !!!!

Dan


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## Ray C (Nov 9, 2013)

Hi Dan...

Thanks for the kind words.

Possibly, yes.   Heat treating can slightly warp things -especially if there are vast changes in part thickness because thicker areas cool off slower than thin areas during the quench.  Also, depending on the material, there could be very slight shrinkage or expansion -but it is barely measurable for small to medium sized parts.  Last, parts that are overheated by as little as 100F degrees beyond the austentizing temperature and if heat soaked too long could sag (a common mistake).

Anyhow, for heat treated parts, I always leave some trued-up non non-critical surfaces so they can be mounted in a chuck etc (in this case, the collars).  When I plan to grind after heat treating, I oversize parts about (depending on size of the overall part) 3 thou.  For these parts, I  don't expect significant dimensional changes and highly doubt anything will need to be done afterward.  It's a very "symmetric" part.   I'll just sandblast them.   Generally, in order to reveal the true hardness, parts should be surface ground etc because the outer 1-2 thou skin layer is damaged by oxidation.  For things like this, its nothing to lose sleep over.

BTW:  I love the look of ground heat treated material.  The results are stunning.

Ray

EDIT:  If you look at the cross-sectional diagrams that were posted, I intentionally designed things so there would be uniform thickness as it transitioned from shaft to collar.  This was done for strength as well has head-off any distortion problems.




buffdan said:


> Ray,
> do you plan on doing any "touch up" after heat treating, like light pass with tool post grinder to 5C taper, or this should be finished product before/after heat treating? Any expectations of dimensional changes?
> 
> Thanks for all of your posts, very much appreciated !!!!
> ...


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## 75Plus (Nov 9, 2013)

Back in March of 2010 I purchased one of these adapters from Grizzly for $30. I just checked to see if they still stocked them and they do, for $98 !!! Glad I shopped early

Joe


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## Ray C (Nov 10, 2013)

Dinner is cooking in the oven.  Tonight's menu:  1045 cooked to perfection at 1550F.  Temperature brought-up very slowly this time (to allow all the seasoning to flavor, 200 degrees at a time.  This goes a long way to prevent warping.  3 gallons of brine water waiting.  The circulating pump will be turned on just before the big chill.  Tempering will be done immediately after they get to 200F.  Tempering at 650F for 1 hour followed by an air cool.  I measured all dimensions very closely beforehand.


Ray


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## Ray C (Nov 10, 2013)

Dinner is served...  and here's some dinner conversation.

When I heat treat these for the full hardening, I wrap each piece in several pieces of paper towel and toss them in a stainless steel bag.  As the oven warms up, most of the paper burns which depletes the oxygen in the oven which prevents oxidation and decarburization.  This then fills the oven mostly with carbon dioxide and carbon monoxide.  As the oven continues to heat, the gasses expand and are expelled from the box.  Since the temperatures are ever increasing, outside oxygen tends not to get back inside the box.   In this case, there was more than enough paper to deplete most of the air.  When the door was opened and the bag was opened, much of the paper effectively turned into charcoal which immediately burns with a flame as soon as the air hits it.

From there, the pieces are immediately tossed into the brine.  This minimizes the amount of time they're exposed to air.  Metal only oxidizes and decarburizes in open air and when at temperatures above 1000F.

Once they cool in the brine down to 150-200F, I put them in an awaiting toaster oven set at 150F and keep them there until the main oven cools down to the tempering temperature.  It takes about 1/2 hour for the oven to cool to typical tempering temperatures.   The metal must never cool below 150F and the temper must take place within 1 hour of the quench. 

 Tempering temperature was chosen to be 650F because I desired this metal to be 45 RC.  This was looked-up in the charts in my cook book.  I chose RC 45 because I know my spindle is RC 50 and it makes sense to have these kinds of attachments a little softer than the main equipment. 

Here they are right as they temper soaked for 1 hour.  I had a few more pieces (all 1045 material) in this batch.  Because of it's size, the big round piece really needed to be in the oven during the heat treating phase for longer than it was kept but, it's not a critical part and I didn't want to over-cook the two taper adapters -so I pulled the batch all at the same time.  The big round piece is about 1" thick.  Nothing on the taper adapters has a cross section more than 1/4".  The big piece should have soaked for an hour but everything was pulled after 1/2 hour.




After the temper, the parts were air cooled to room temperature to allow them to pass below the Martenizing phase.  On the big round piece, I did a quick surface grind and did a hardness test.  It's reading a very solid Rockwell 43C.  It's two points low because it didn't heat soak long enough.  I don't want to put a ding mark in the taper adapters but, I can all but guarantee they are RC 45 as planned (smaller pieces get harder, faster than bigger pieces).

Here they are just quickly sandblasted.  I checked all the dimensions once they were room temperature.  Absolutely, positively no differences in readings  in any length or round dimension.




Ray

EDIT:  Moral of the story:  If you follow the procedures, practice your techniques and use good thermometers, you can do dead-on precision heat treating in a home shop.  Most important, almost all forms of warpage and undue shrinkage are vastly minimized (if not completely eliminated) using good procedures.  These are the benefits of modern textbooks and years of work by metallurgists...


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## xalky (Nov 10, 2013)

Awesome job Ray:man:.  I want to see pics of your oven and rockwell tester.  That's something I might want to get into as time goes on. I learned all about metallurgy in engineering school but I forgot most of what I knew from lack of exposure. How'd you get your hands on a rockwell tester? Aren't they real expensive?

Marcel


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## Ray C (Nov 10, 2013)

xalky said:


> Awesome job Ray:man:.  I want to see pics of your oven and rockwell tester.  That's something I might want to get into as time goes on. I learned all about metallurgy in engineering school but I forgot most of what I knew from lack of exposure. How'd you get your hands on a rockwell tester? Aren't they real expensive?
> 
> Marcel



Here's plenty of info about the heat treating oven.  It's home designed and made.  http://www.hobby-machinist.com/showthread.php/9929-Heat-Treat-Oven?highlight=heat+treat+oven

Rockwell testers are fairly easy to come by.  I have a Brinnel impact type and a simplified rebound type that reads in Rockwell C scale (which actually gives more consistent results than the Brinnel unit).  I've tested them against proof-pieces and they read within +/- 1 point of the proof pieces.  I'd like to get an electronic LEEB tester -maybe some day.


Ray


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