Morse taper extensions?

When using a morse taper extension, does the work piece weight specs on the center stay the same with the extension? I am using a MT6 male to MT6 female extension in the spindle with a dead center in the extension. I am turning rolls between centers with this setup. I am no way near the weight(load) specs of a MT6 dead center but I don't how the extension comes into play.

Take with a pinch cos ive never used an extension.

The centre would see the same load set in an extension or spindle. The spindle or whatever the extension is mounted into would see an increased load though.

Im guessing the things to keep in mind are the spindle capacity, that the extension is strong enough and being respectful of cutting forces involved, doc/feed etc.

Im thinking of it loaded like a beam.

Got any pics of the setup?

Demon73 said:

that the extension is strong enough

Got any pics of the setup?

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I think that this is what my original question is, I probably didn't word it correct above. It is a Collis brand.

This extension ? http://www.collistoolholder.com/cgi-bin/item.cgi?part=60666

Bearing in mind the over hang etc etc. Although I'm not an engineer, to play safe I'd reduce the load to 20% of max and ''take it easy''

Limy Sami said:

This extension ? http://www.collistoolholder.com/cgi-bin/item.cgi?part=60666

Bearing in mind the over hang etc etc. Although I'm not an engineer, to play safe I'd reduce the load to 20% of max and ''take it easy''

Click to expand...

I agree, you're using the adaptor for a purpose it wasn't designed for.

Regards Tyrone.

Limy, yes that is the extension. What would you base the 20% on, capacity of dead center, spindle max? We are putting a 1500 lb roll max in the lathe. I think cutting forces are minimal, there is a rear mounted grinder resurfacing rubber rolls.

Tyrone, when you get up to that size extension what would the intended use/application be?

oxford said:

...Tyrone, when you get up to that size extension what would the intended use/application be?

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Whatever the taper size, Morse taper extensions are meant to hold Morse taper drill bits or reamers in order to drill or ream holes in places the tool can not otherwise reach. In that application, there is no side (bending) load on the extension or the driving spindle. So, there is no weight specification for an MT extension. The diameter of the extension is designed to safely withstand the torque of the largest drill bit with a 6MT shank, which I have never seen, but must be rather huge.

Larry

oxford said:

Limy, yes that is the extension. What would you base the 20% on, capacity of dead center, spindle max? ?

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Gut instinct and survival ! ..when you start using things for which they are not intended, especially with machine tools, thing's can and do, go wrong, ......and the bigger the workpiece and or machine, the bigger the wrong.

L Vanice said:

Whatever the taper size, Morse taper extensions are meant to hold Morse taper drill bits or reamers in order to drill or ream holes in places the tool can not otherwise reach. In that application, there is no side (bending) load on the extension or the driving spindle. So, there is no weight specification for an MT extension. The diameter of the extension is designed to safely withstand the torque of the largest drill bit with a 6MT shank, which I have never seen, but must be rather huge.

Larry

Click to expand...

That post spells it out loud and clear.

The longer you work at the Iron Game the more you see things go wrong.

So I take it you've got the roll between chuck and centre ? That's 750 lbs acting at 90 degrees on the transition point of a No 6 Morse adaptor. And the male end of the the adaptor is in the tailstock barrel, there's a large centre in the female end ? I'd try the the roll in the lathe but I'd have a DTI under the adaptor to see how must deflection you get when you let the crane off. If it doesn't deflect much I'd give it a whirl, starting off slowly of course. I take it the roll is pretty well balanced.

" Who Dares Wins ".

Regards Tyrone.

Tyrone Shoelaces said:

So I take it you've got the roll between chuck and centre ? That's 750 lbs acting at 90 degrees on the transition point of a No 6 Morse adaptor. And the male end of the the adaptor is in the tailstock barrel, there's a large centre in the female end ?

Click to expand...

Sort of. Live center directly in the tail stock, there is a spindle taper to morse taper adapter in the spindle, the male end of the extension goes into that and then a regular MT6 dead center in the female socket of the extension.

oxford said:

Sort of. Live center directly in the tail stock, there is a spindle taper to morse taper adapter in the spindle, the male end of the extension goes into that and then a regular MT6 dead center in the female socket of the extension.

Click to expand...

OK, So why is the extension needed? Is the center hole down inside a deep bore or something?

Derek Smalls said:

OK, So why is the extension needed? Is the center hole down inside a deep bore or something?

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Here is a picture of a similar lathe



Notice that the ways do not go totally up to the headstock, it is not missing a gap piece. When the carriage goes up to the end of the ways, the grinder will not reach the end of the roll when it is in a regular center in the spindle.

Original plan was to offset the grinder to reach the end of the roll, the problem with the grinder offset is when it is at the tailstock end it won't reach the other end of the roll before the carriage hits the tailstock or the grinder hits the tailstock on the smaller diameter rolls even with the quill all the way out.

The next option was to run a center in the chuck. The 4 jaw that came with it is too big to be spinning around just to hold a center plus it about border line of the higher end of the rpms we run. The 3 jaw that came with it would work but it has 1 piece jaws and only an inside set.

While trying to track down chuck jaws and get a morse taper to straight adapter to hold in the chuck I came across the adapter. It was the right length and didn't have to have a needless chuck spinning around. I didn't know that it wasn't usable in the application I wanted to use it for.

So this is at the point I am at now, trying to figure out if this will work and not break and have a roll come flying out of the machine. Not to mention that management is wanting this up and running and the boss pretty much dumped this on me, just the guy that gets to run it.

I'm not there, but I think what I would do is use the three jaw(if you absolutely don't want to use the four jaw), make a plug that will snugly fit the bore of the chuck itself, with a small shoulder that will sit on the face of the chuck. Clamp down on it with what you can of the "wrong" jaws. The back side of the plug will have a tapped hole(3/4-10?), which a piece of threaded rod can be threaded into which will pass through the spindle and have a washer/nut retaining everything on the far end of the spindle. The working end can now be as long as needed, being it a large enough dia. that it won't flex or break, and a center can be turned on the end of it.
I'm not saying the extension WON'T work, but it seems too iffy for my comfort. The above described setup won't go anywhere, and is easy/cheap enough to do with what you have on hand.

I think a turned centre clamped in a chuck sounds like a much better proposition than the extension.

I'm getting my head around the issue now. A photo of the roll would be very useful. I expect it to have shafts at either end but knowing exactly what it looks like would be good. Making your own extension centre could be the way to go.

I see you've got a " Poreba " lathe, I've worked on quite a few just like the one in the photo. They're a decent lathe for the money. I've had the usual problems with coolant in the apron though.

Regards Tyrone.

Tyrone Shoelaces said:

I'm getting my head around the issue now. A photo of the roll would be very useful. I expect it to have shafts at either end but knowing exactly what it looks like would be good. Making your own extension centre could be the way to go.

I see you've got a " Poreba " lathe, I've worked on quite a few just like the one in the photo. They're a decent lathe for the money. I've had the usual problems with coolant in the apron though.

Regards Tyrone.

Click to expand...

Sorry no pictures of the rolls but what you expect is correct. We have a few different sizes but the common ones are around 11" diameter with an 86" face and has 3" diameter journals sticking out the ends about 3" long. The other rolls are similar configuration.

Would you be able to expand more on the coolant in the apron problem?

oxford said:

Sorry no pictures of the rolls but what you expect is correct. We have a few different sizes but the common ones are around 11" diameter with an 86" face and has 3" diameter journals sticking out the ends about 3" long. The other rolls are similar configuration.

Would you be able to expand more on the coolant in the apron problem?

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Like most lathes coolant can find it's way into the apron if you use coolant a lot.

Any oil in the apron floats on the coolant and is gradually expelled. You end up pumping coolant instead of oil around the gearing and up to the ways.

There is a simple solution - drain the sump every 3 to 6 months and replace the oil. We're only talking about a few pints at the most.

Regards Tyrone.