Thread: How much to tighten NT30 drawbar?

How much should I tighten up the drawbar on my BM-22AD NT30 mill? Can anyone give me an approximate torque rating?

I read snug tight but it's so subjective. I read on another site that it is " the full force of an ironworker (say 100# to 150#) using an ordinary spud wrench (16in - 18in long). On the low end you're looking at 133 ft-lbs and at the high end you have 225 ft-lbs of torque."
This seems like too much.

Also, are power drawbars all expensive as hell? $800 at H&F and couldn't find any cheapies on ebay. Perhaps making one is the way to go (?)

I would expect you just need to nip it up firm but not white knuckle tight. The drawbar is only seating the arbor up against the taper for repeatability. The rotating force is taken up by the drive dogs.

Simon

Sent from my SM-G900I using Tapatalk

Snug tight pretty much covers it and Simon's reply is right on the money.
I engage low gear on my RF45 mill with NT30 quill and give the drawbar nut a few sharp tugs with the spanner till the quill just starts to rotate.
To release, just back off the drawbar nut a turn or so and a sharp tap with a light hammer will release it.

Alan

A firm tap of my palm of my hand on the spanner is all I've ever used, never had anything come loose.
Power drawbars used to come up on ebay from an aussie company for around $500, but much cheaper to make one.
If you don't want air running all the time, go to a 18v battery impact driver, there the same torque as the butterfly wrench everyone uses. Just make a manual pull down one.

Sent from my SM-G900T using Tapatalk

'Firm' is the perfect description. Hand tight, without any straining. Just past the point where you feel the resistance of the drawbar going tight. Low enough to tighten and loosen with the spindle in low gear.

As said above, I was given an old mill some time back, the draw bar was so tight I had to hit hard enough with the hammer that it bent the drawbar

Try and explain the concept of nipped up to a metals class of high school students.
Nipped up translates in some cases to eyeball popping tight. Our mill was the HM52 with NT 30 arbor with the lugs.

I had to make a dedicated spanner with a short handle to minimise the problem.

Removal was often incorrect as in unscrew so theres no thread engagement ,then beat the bejesus out of the drawbar so the thread gets mashed and cutter arbor free falls and chips the cutter on the table because arbor was not supported with the hand.

I understand your pain Grahame. My son is 14 and seems to be going through a phase of just breaking everything. Its either brute force, ignorance or just always in a hurry to do something. I got a neverending list of things to fix around the home. Does my head in!

Last item was his nans (my mum) toilet roll holder ripped off the wall! Of course its not his fault.... just ask him!

Sent from my SM-G900I using Tapatalk