The one I bought years ago was M8 so just made another draw bar.

I assume you are based in the UK, it seems Amadeal will be able to supply you soon (if you can wait).

Thor

Make a 3/8″ drawbar to suit the collet.
My mill came with a 1/2″ drawbar and I also have collets and tool holders with 3/8″ and M12 threads. The drawbars are just a piece of threaded rod with a hex nut on top. Screw the rod down into the collet, then tighten the nut.

I had a problem even greater when I converted the Tom Senior light vertical from MT2 with a 3/8W drawbar to R8 which usesa 7/16 UNF drawbar. I wished to keep the top section and marry it up to a new R8 bottom from ARC. The top half was splined for the sliding drive. I managed to get a hand reamer with its longer lead in to start and when it reached its full length from both ends, silver soldered on an extension to reach the middle. The hole in the bottom part was already the correct size.

A hand 10mm reamer would easily increase the bore of the 3/8W leadscrew hole, andnot prevent the 3/8 from being used with compatible tooling. I turned the reamer handle end down in steps and drilled matching holes in the extension which had the end squared for a tap wrench after silver soldering. This could be done without removing the spindle from the mill. A normal 10 mm piece of studding will be under 10 mm diameter, they always are.

Another problem, is now that many arbors come with a M12 thread for the drawbar, when the existing drawbar is 3/8 BSW.

Trying to drill and tap a piece of M12 studding with a 3/8 BSW is likely to lead to disaster.

Unsupported, the roots and crests are so close that tearing is almost inevitable.

Screw and Loctite, a short length of M12 studding into the arbor. If possible, grip on a plain diameter, and face the end before drilling and tapping 3/8 BSW.

Howard

I also have some MT2 with 10mm threads, 12 mm would be too big for the small end.

On 20 June 2025 at 22:41 William Ayerst Said:

@Bill – are you able to elaborate on what that new VH cap does and how it works? I’ve not recently had a need to swap out the drawbar but it is a bit of a faff!

William, It’s not a new cap, just a fancy spanner.
It’s a pain to remove the top hat retainer with something like an angle grinder peg spanner.
The item shown replaces the peg spanner; It’s just a lump of round bar, with a through hole, which drops over the top of the drawbar, after removing the alloy safety cup.
The pegs engage on the pair of holes on the top of the top hat nut/retainer and the top of the drawbar stops it falling off.
Internally, the hole retains concentricity, and the external 17mm hex fits a short combination spanner.
I use the spanner inverted, and it effectively just becomes a handle to remove the draw bar retainer.
Replacement is also easy, as all you have to do is swap the draw bar from imperial to metric or vice versa, compress the spring, and wind the top hat nut back on.

It’s a matter of less than a minute, only delayed, as since I found a riser block, I now need a small stool to easily reach the top.

Let me know if you need a more detailed photo of it in use.

Bill

On 20 June 2025 at 12:25 Howard Lewis Said:

Another problem, is now that many arbors come with a M12 thread for the drawbar, when the existing drawbar is 3/8 BSW.

Trying to drill and tap a piece of M12 studding with a 3/8 BSW is likely to lead to disaster.

I get that problem from time to time with ISO 30 tooling for my milling machine. I make an adapter from a piece of 5/8 bar. I drill and tap it 3/8W then screwcut the external M12.