Have you got a MT dead centre you can drop in?
mines a vevor but looks oddly similar…. But I have an opening at the top that’s just round bore then it goes into a taper further down but a dead centre fits nicely and allows easy alignment

Quick and dirty test is to use a pair of appropriately sized washers, one large and one small, the right distance apart to pretty much match two rings on the expected taper bore. As it’s a separating the sheep from the goats thing great accuracy of spacing isn’t needed. Locking each between two nuts on a piece of threaded rod will do.

Or you could use one at a time fitted at the end and measure the depth each one goes into.

Second method is more accurate but I’ve found it easier to set up the washers to be two points on a taper before dropping in to see how much it all wobbles.

Worst bit is figuring out what size washers make sense. Probably have to make them.

Clive

Remember that MT2 and MT3 are very similar but not identical taper angles so just putting it in is not a good test. Put engineering blue on it and check the fit.

Not unusual for these and the far eastern ones to have a bush with the MT2 internal taper, maybe your bush has been lost. You can also see the step that the bush fits up against which is probably the step you mention stopping the MT3 going in.

On 4 November 2025 at 20:35 Martin Currie Said:

I’m wanting to make a taper to help with alignment

What part of the taper is crucial to helping with the alignment?

All you need is something that is a snug fit in the table, whose projecting outside diameter is concentric with the hole in the table.

There is some disadvantage to using a tapered item for this purpose: if you drop it into the hole with anything but the lightest touch, once you have done your alignment, it can be difficult to remove if the taper sticks.

On 5 November 2025 at 07:10 Diogenes Said:

…It looks like yours has a ?24mm ?parallel socket – arguably a better system anyway.

When I made my small R/T, a straight socket is what I used, it accepts Precision Ground Mild Steel pins which go in and out with a ‘pop’ fit, and allow various spigots / split centre etc. to be used.

+1

My 12″ (no name) rotary table has a 1″ parallel bore in the centre which is far more useful than a taper for the reason given above.

Julie

Have a 24mm dia “slug” that drops in the bore with an accurate centre drilled in the end. Put a centre in mill spindle, bring down quill so it engages with the centre in the RT, get the table snugly aligned, then tighten it down to the mill table.

The method of centring a chuck by this method is, at best, hit and miss, relying on the quality of the chuck.  We all (should) know that most three jaw chucks are not good for concentricity – certainly not for all diameters.  The chuck will only be centred for the diameter of the inserted post and not necessarily for other diameters.

It is one of the reasons why we do not remove and replace items, for later machining operations, when using a scroll chuck.

Having a good Pratt Bunerd scroll chuck normally fitted to the rotary table I usually fit a test bar in the MT2 hole in the top and gently clamp the chuck jaws onto it before bolting the chuck down. The 7″ long test bar also serves to align the spindle if necessary. If the concentricity is vital, I would resort to the use of an indicator. That chuck holds all diameters with less than 0.002″ tir throughout its clamping range with both sets of jaws. Many people have never actually tested scroll chucks to find the errors and also the best key position. They also have tight registers onto the chuck backplates so that errors cannot be minimised, and then moan about scroll chucks being useless. They are also the same ones that cannot be bothered to use a four jaw independent because it takes longer to adjust.

I think I won’t be trying to remove the bush from the Soba table top, let sleeping dogs lye.