Spindle question

[Tigman]

The Lathe I have has an 82mm spindle , if I wanted to machine between centres how does the centre fit the spindle , the manual says the spindle is M5 on one page , and 82mm bore on another page , what am I missing ??

 

[MattF]

There'll be a taper at the front internal end of the spindle. The centre fits into that.

The bore measurement relates to the internal diameter beyond the taper.

 

[Agroshield]

Can you say what lathe it is? Can you provide a link to the manual?

M5 is either a sporty BMW or perhaps Morse taper 5. However, if it is 82mm bore, the car is probably a closer fit as the large end of Morse 5 is less than 50mm. It is possible it needs a spindle bush to reduce from whatever it does have to MT5, but this is speculation.

 

[Tigman]

The bore of the spindle is 82mm , there is no taper at the front , it's D1-8 fitting , it's a Chinese lathe , viking vt515, the M5 I take it is morse taper , but there is no way that works I have a plate with a pin but the bore of that is more like 100mm, I assume that there is a bush missing that fits the 82mm and is tapered in itself ?

 

[E T]

Morse taper 5 would be either MT5 or MC5 depending on where the lathe is made. M5 is not normally used for a morse taper.

 

[Agroshield]

The poor man's way of machining between centres is to chuck up a piece of round bar and turn a 60 degree point on it. You know it will be true to the lathe's axis.

Only rarely do you need the extra distance that removing the chuck and running the centre directly in the spindle provides.

 

[Tigman]

I'm just asking the question , will never do it realistically ,this is the manual page , there is no taper on the spindle so must be something amiss

 

[Agroshield]

M5 is not normally used for a morse taper.

Now he has posted an extract of the manual, it says the tailsock (sic) [the other one of the pair is in the cabinet underneath] has an M4 taper so the M5 = Morse 5 would at least be consistent with that useage.

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I found some pictures of the machine and it bears a resemblence to the type of machine that the Cutting Edge YT fellow has. Maybe you could find an equivalent machine made by someone else that has better documentation. Grizzly in the US would be agood place to start as their manuals are usually quite good.

Edit:

If you search for '82mm spindle bore', there are lots of same breed appear. They are all a bit vague about any spindle taper. Two of them (BSA being one) mention a 1:20 taper so it might be worth measuring/verifying that your bore is truly parallel just to rule that one out.

 

[Tigman]

My manual is fine

Can't find part 52 though

And my Matchine works fine

 

[Pete.]

Measure the spindle hole at the back, and at the front. Are they the same?

 

[Tigman]

I do have a mt5 centre in the box of tools , the tail stock is indeed mt4 , this suggests that a bush of some sort is missing

 

[Tigman]

It certainly looks to be parallel 82mm all the way

 

[Pete.]

I guess you need a spindle bush. Not much point making a parallel to MT5 bush if all you want is a centre. Turn a bush that's a good light press fit in the hole and then turn a point on it.

 

[Chippie]

My lathe has a 38mm bore at the drive end, MT5 taper at the chuck end….takes 1-1/2” bar stock no problem…

 

[Tigman]

Thanks Pete , I can see how that would work !
I've had a good search online but could not find anything that resembles a spindle bush

Thanks for all the replys

 

[Sergei Slovenija]

If the lathe chuck has minimal runout, should I buy a cylindrical bushing with a 4 or 5 taper and clamp it in the chuck

 

[E T]

Correct me if I'm wrong, but as I see it a spindle bush without an outside taper would just push further into the spindle under the cutting forces and the pressure from the centre in the tailstock. A tight fitting bush with flange might work.

 

[E T]

If the lathe chuck has minimal runout, should I buy a cylindrical bushing with a 4 or 5 taper and clamp it in the chuck

Easier and more accurate to chuck up some roundstock and turn a 60 degree point on that.

 

[Tigman]

Correct me if I'm wrong, but as I see it a spindle bush without an outside taper would just push further into the spindle under the cutting forces and the pressure from the centre in the tailstock. A tight fitting bush with flange might work.

That's what I was thinking that the Bush somehow fits in the plate I have which is D8 , it has the pin in it to drive a dog but the centre of this drive plate is over 100mm , I should have taken a picture of it before I came home

 

[Pete.]

It's normal for the dog plate to have an over-sized hole. Mine is about an inch bigger than the spindle bore.

ET is right you can always turn a centre in your chuck each time you need to do between-centres turning, so long as you have the between-centres distance to accomodate your part.