More about Mills

[Will_D]

Another mill related question:

Drawbar Standards:

Are there any standards for draw bars?

I would suspect that R8 has a standardised db thread

But what about MT 2 & MT3 - some tools are metric others imperial (Whitworth)

If I am lashing out over 1k on a new mill I want to know whats what.

Also before I accept delivery of the Mill I need to know if it comes apart easily!

Anyone have a parts diagram for the Warco WM16 or the Amadeal AMA25? If so please PM me

[awemawson]

R8 is 7/16 UNF

MT come is all sorts of flavours

[Arbalist]

Many Morse taper mills come with a 3/8 Whitworth draw bar. Mine did but I never use it as the supplier I got my collets from use M10 for MT2 and M12 for MT3. I just use M12 threaded rod with a nut on it. I've been meaning to make a self ejecting drawbar but haven't got round to it.

[John Rudd]

The draw bar depends on whatever is used in the quill....
I have a 2 in boring head with an MT3 taper...it is tapped 3/8BSW...the ER32 collect chucks I have are all tapped M12....I also have a face mill that is MT3, that too is M12......

[BaronJ]

Generally speaking, if the machine accessory, collet, boring head ect is metric then the drawbar will be metric threaded.  The same for imperial accessories, they will have imperial threaded drawbars.

HTH.

[sparky961]

Many Morse taper mills come with a 3/8 Whitworth draw bar. Mine did but I never use it as the supplier I got my collets from use M10 for MT2 and M12 for MT3. I just use M12 threaded rod with a nut on it. I've been meaning to make a self ejecting drawbar but haven't got round to it.

Self-ejecting drawbar?  Do tell!

[chipenter]

You can get a R8 to morse converter but not the outher way round http://www.arceurotrade.co.uk/Catalogue/Adaptors-Sleeves , I would go with R8 .

[Bigbadbugga]

Many Morse taper mills come with a 3/8 Whitworth draw bar. Mine did but I never use it as the supplier I got my collets from use M10 for MT2 and M12 for MT3. I just use M12 threaded rod with a nut on it. I've been meaning to make a self ejecting drawbar but haven't got round to it.

Self-ejecting drawbar?  Do tell!

My chester 20v mill has one, when you undo the draw bar the top nut is held in a cup so it can't screw out the top, instead it pushes the rod down and ejects the taper.

[Jonny]

Can get MT2 in 3/8"BSW, M10 and M12
MT3 in M10 and M12, may be more.

Just make up drawbars with desired thread if have several different tools. Spare MT3 mill unused had 3/8" BSW that came with it and made up two in M10 and M12 to suit the collets and tools had at the time. Easy enough to make.
Current mill is MT3 only have the M12 drawbar as all tooling is M12.

[sparky961]

My chester 20v mill has one, when you undo the draw bar the top nut is held in a cup so it can't screw out the top, instead it pushes the rod down and ejects the taper.

That's cool.  My MT3 is always a pain.  I know that they're designed for a drift but there's rarely room to extend the spindle, and you'd need to undo the drawbar all the way... ya, definite pain.

[Arbalist]

 Finally got round to making a self extracting draw bar for my mill, works well.

[sparky961]

Pictures?

[Arbalist]

Pictures?

It's not very interesting...



Tool end is standard M12x1.75 and the nut end is M14x1.25 (Spark plug thread!)

Made from some 12mm steel rod and a lump of 3/4 steel hex pinned together with an M5 roll pin.

Not my idea, of course! the difference in thread pitch forces out the collet as you undo the draw bar. All I had to do was cut the M14 thread in the top of the mills spindle.

To be honest though it's never been a chore giving the standard draw bar a swift tap with a copper and hide to eject collets. Unlike an R8 taper that needs a fair bit of torque to hold it in place, MT tapers are self locking and only need to be nipped up a little in most cases.

Just thought it was an interesting project and I already had the materials! 

[sparky961]

Thanks for the picture.  Its sometimes usually the mundane things that make all the difference. 

You're right that it doesn't take much to release the collet if you don't overtighten, but sometimes over-tightening is "necessary" to close the collet on a slightly smaller diameter than what's ideal.

There happens to be a bedroom above where I use my mill; sometimes quite late into the night/morning hours.  So a quieter option than smacking the drawbar is very desirable.  And for those of you thinking this is a bit strange due to the overall noise a mill makes, continuous noise doesn't seem to be a problem.  It's the times where excessive chatter is occurring, or smacking something with a hammer that tend to awaken Sleeping Beauty.

What does the M14 end thread into?  Have you modified the top end of the spindle, or is there an internally threaded component you've attached thereto?

[sparky961]

Ok, apparently I scanned your post a bit too quickly.  You did mention the modification to the mill.

[Arbalist]

Yes, you do get the odd cutter that seems to need a bit more torque to close the collet on it. I'm using an ER32 chuck a bit more often these days as well. I probably wouldn't have bothered buying one but I already had a full set of ER32's I bought for the Lathe.