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Milling drawbar

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Paul Vassallo10/07/2011 14:15:17
12 forum posts
Hi
 
I have recently bought a secondhand bench milling, and when I got it home, and it came to fitting a collet chuck I foundout that it has a MT3 and a drawbar M11 x1,25 pitch. Can somebody help me and tell me where I can buy an M12 x 325MM long Drawbar.
 
Thank for all of you that are willing to help.
 
Paul Vassallo
JasonB10/07/2011 14:37:53
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Your best bet is to get some 12mm rod, thread both ends and then silversolder a nut onto the top end. Doing the same with some studding (threaded rod) is another option. In both cases make sure you allow for a heavy waher under the nut.
 
That length is quite close to an X3 mill I'll measure mine later
 
Jason
 
PS whats the make & model of the mill

Edited By JasonB on 10/07/2011 14:47:01

JasonB10/07/2011 15:29:47
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X3 is too short
DMB10/07/2011 17:49:52
928 forum posts
Agree with JasonB, regarding make your own drawbar but Paul should go one better and copy my previous post describing the trapped nut which forces the MT apart gently instead of a hammer/brute force, wrecking bearings in the process.
 
John
DMB10/07/2011 17:58:16
928 forum posts
Look up "Milling collet arbor jammed in milling machine" of 4 June 2011, in Forums.
 
John
Paul Vassallo10/07/2011 18:33:28
12 forum posts
Thank you for all the help, the idea that jasonB gave me the best, but one more thing about the material of the rod, will silver steel do?
 
Paul
John C10/07/2011 18:39:41
243 forum posts
87 photos
Hi Paul,
 
In the UK, Screwfix do 12mm threaded rod in 300mm (maybe too short for you) and 1000 mm:
 
http://www.screwfix.com/p/bzp-threaded-rod-m12-x-1000mm-pack-of-5/98942
 
The price is OK, although you will have to find a use for the other 4 lengths!
 
John
JasonB10/07/2011 19:29:01
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Good old mild steel will be fine, you don't need to be applying loads of torque to the drawbar, just nip it up.
 
The taper takes the drive load the drawbar is mostly there to stop the tooling falling out the end of the spindle.
 
Though at 13" long a bit of silver steel may be easier to come by (at a price) but most of the ME suppliers or certainly your local steel stockholder will be able to supply longer than the 12" thats often listed in their catalogues.
 
Jason

Edited By JasonB on 10/07/2011 19:30:45

David Haynes11/07/2011 08:21:52
168 forum posts
26 photos
Paul, if you have an industrial estate within reasonable reach, you may be able to pick up a piece of studding there quickly, easily and cheaply. We have an engineering suppliers that did the trick for my studding and other bits.
 
Dave
Lawrie Alush-Jaggs11/07/2011 11:12:27
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118 forum posts
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Hi Paul
 
The first place I would try is Ebay, then Warco. Failing that I would make on up but I would steer clear of Allthread and get a peice of something with a bit of carbon in it, a bit of 1020 or 1045 rod.
It won't set you back much. Get a bit of hex while you are at it and when you have silversoldered the nut on, make sure you put a pin through it as well.
 
Lawrie
Lawrie Alush-Jaggs11/07/2011 11:16:53
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An addendum
 
I use Bohler Udehom here in Australia. They have an excellent range of steels including the ones I mentioned above and will supply any quantity.
 
John Haine11/07/2011 17:58:52
2662 forum posts
136 photos
Last thing you need (especially with a Morse taper) is a very strong drawbar. Studding is fine, you can even buy stainless if you want something a bit fancier than the builder's merchant stuff. Biggest danger with MT is overtightening the drawbar and jamming the taper.
Dusty11/07/2011 19:13:49
466 forum posts
8 photos
Hear hear John, I have 4 drawbars for my mill with a variety of threads. I only have one which is a pukka drawbar the rest are studding with a nut on top, this nut just has a roll pin through it. As JasonB says it only needs a nip up, none of this he-man stuff. You can if you want make the nut with an integral washer, tap it not quite through so the studding is a nice tight fit, cross drill for roll pin and thats it job done. One other thing make sure the drawbar does not bottom in the morse taper thread.

Edited By Dusty on 11/07/2011 19:16:00

Steve Withnell11/07/2011 22:37:40
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794 forum posts
215 photos
I didn't bother soldering on the nut, I just locked two nuts together...I t used 12mm studding from the local DIY store and then repeated the trick for the lathe.
 
Steve
Ian S C12/07/2011 04:49:12
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7447 forum posts
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Needed a drawbar, no studding available, took two bolts, one to fit the cutter. Cut the heads off, welded the two cut ends together, put two nuts on the top end, welded the top one to the drawbar. With the assistance of my scrap bin, about 10 miniuts. You could weld two bolts to a bit of rebar. If your welding is anything like mine, it wont look pretty, but thats no matter. Ian S C
John McNamara12/07/2011 07:06:04
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1309 forum posts
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Hi All
 
Do we overtighten the drawbar? I suspect so.
 
I did the following Google search:
"Torque on a Nut"
  
Found these among many:
 
 
When I got my new (old) mill I exprerimented with the torque needed to set the tool firmly, Using a short spanner; after taking up the slack a firm push is all that is needed. Getting the taper to unlock is now only a light tap on the top of the drawbar.
 
Looking at the torque tables above it is clear why this is so. How many thousand pounds or kilograms do you really need to set a milling cuter?
 
Cheers
John

Edited By John McNamara on 12/07/2011 07:08:30

Ian S C12/07/2011 11:28:55
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7447 forum posts
230 photos
I forgot, under the lose nut on the top puta heavy large diameter washer. Ian S C
Pat14/07/2011 21:50:05
94 forum posts
1 photos
Hi John Coleman1
 
Can we have a repeat of your post as your design for a self releasing draw bar sounds good.
 
May be I am looking in the wrong place as the last post in the thread 'milling collet arbour jammed in milling machine' is June 2010.
 
Help please - Regards - Pat
 
PS found post as June 2010 and have pasted it here:- 
 
Julian,
"Been there, done that"
My long-term solution as follows.
Trapped nut system works like a dream - try it!
I made new drawbar with nut just touching top of mill spindle, remove, cross-drill + pin.
Large AF hex bar bored out to fit over top of mill spindle and locked on to it with 3AAllen key grubscrews.The rest of it drilled right thro` clearing size for drawbar thread. Make new smaller AF nut, taller than standard, fit  on top end D-bar + wind down to just touch top of large AF nut, cross-drill + pin.
John  

Edited By Pat on 14/07/2011 22:04:09

DMB15/07/2011 01:05:03
928 forum posts
Hi Pat,
I used BMS round bar, NOT Silver Steel for my drawbar. Sil. St. not necessary. Bottom end threaded to suit MT, top end same thread as for the MT. When finished, there is a nut pinned to very top end, along piece of large - AF Hexagon bar, part - bored out to fit over top of mill spindle and locked on to it with 3 grub screws fitted radially and top end is bored out to a clearnce size for drawbar. Another nut is fitted to draw inside the large hex. bar, so its trapped. When the top nut is turned clockwise, it screws thro. the trapped nut and bottom end screws in to MT, drawing male taper into female taper in spindle. Dont over tighten - just nip it up to secure it. When top nut is turned anti - clockwise, drawbar unscrews thro. trapped nut and from MT. The trapped nut wants to stay put and rise up with the unscrewing of the drawbar from theMT but its trapped and cannot move vertically thus preventing drawbar from moving vertically. Something has to give and its theMT shoved down, breaking its grip. Is this now all clear? Hope it helps.
John
Jon17/07/2011 16:54:26
989 forum posts
46 photos
Have had MT3 shank holders drop by only 'nipping' up.
Not to mention the cutters held in them, even worse.

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