Milling machine drawbar

klemchuk · Nov 17, 2011

Does anyone here know what grade of steel is used for a decent drawbar.
The one that came with my machine had a pin crossways through both large and small sections to join them, it was ground smooth and painted over to make it look like it was
one piece. The break happened at the pin of course.
I'd like to make a new one but would like some input as to type of steel to use.

oldbikerdude37 · Nov 17, 2011

klemchuk said:
Does anyone here know what grade of steel is used for a decent drawbar.
The one that came with my machine had a pin crossways through both large and small sections to join them, it was ground smooth and painted over to make it look like it was
one piece. The break happened at the pin of course.
I'd like to make a new one but would like some input as to type of steel to use.

Don't do a cross drilled type if you dont have to. some you do have to and they suck. self extracting type do and tend to fail. I want to kick some tool designers right in the balls.

67Cuda · Nov 17, 2011

Make a draw bar? Just buy one that works.

I worked for a couple of German tight wads, that bought draw bars that had two sections of threads. So that if you stripped the cheap shit metal off of the first section, you could cut it off and use the second cheap shit section.

Tom

Ohio Mike · Nov 19, 2011

A Bridgeport J draw bar isn't worth making they're like $15-20 but if you have an odd machine (Van Norman, Cincinnati etc) then making one is the only way to go. Curious that no one has any thoughts on what to make one out of. I've used ordinary cold roll and 1144 myself. Material wasn't a concern for me since the machine isn't production duty.

Mike C. · Nov 19, 2011

Gotta agree with buying one for an R8, but... drawbar only holds the tool against the taper. All you really need is a lenght of threaded rod, if it is a drawbar with male threads.

If it's a VN type with a tubular drawbar, you might want to go with something like 4130 or 4140, just to make the internal threads nice and crisp, versus plain old mild steel that may wad up and tear on the fine internal thread.

Mud · Nov 19, 2011

After stripping a couple I welded a grade 8 bolt on the end, worked for 20 years so far. For the rest of the drawbar mild steel is sufficient.

SND · Nov 19, 2011

4140, cheap and easy to get.

John Welden · Nov 19, 2011

If it is an r8 Bridgeport style, buy or make one with an extra long hex section. That way you can put your palm on it and give it a couple good flings to unscrew it. Nothing is worse than fiddle farting around with a dumb little hex nub sticking out. 30 seconds extra times 20 tool changes is 10 minutes.

Think NASCAR pit crew instead of union machinist trying to take as long as possible.

Newman109 · Nov 19, 2011

When I got my Webb Mill, it had a Snap Changer on it with a special drawbar but there were no collets with it. Since the Snap Change collets are someting like $100 apiece, I sold the unit and made a new drawbar out of a piece of 7/16" 4130 rod that I had in my stock bin. I used a piece of stainless 3/4 hex for a head and welded that on. EDIT: As J.W. mentions above, I left the hex about 5" long so I can get at it. The mill is very tall.

That was two years ago and it's still holding. It worked for me. I have plenty of material to make some more when that one wears out.

Greg White · Nov 20, 2011

I have often repaired the threaded end with a little lathe work and a short car ride to the Tool&Die welder around the corner,useing a shank of a SHCS.
Omly in a pince,if I can wait till its shipped, I dont mess with them.
Gw

moonlight machine · Nov 20, 2011

John Welden said:
If it is an r8 Bridgeport style, buy or make one with an extra long hex section. That way you can put your palm on it and give it a couple good flings to unscrew it. Nothing is worse than fiddle farting around with a dumb little hex nub sticking out. 30 seconds extra times 20 tool changes is 10 minutes.

Think NASCAR pit crew instead of union machinist trying to take as long as possible.

Thats what they make power drawbars for.....I would not be without one.

Uguessedit · Jul 14, 2018

Every time I’ve used an extra long hex it’s wobbled and caused harmonics down the spindle affecting the cut. Not even sure why anyone would use them based on my experience but if they work for others great. 3 mills here and all had the same issue with a 5” long hex whipping around at 6500rpm. Besides that if you end up adding a power drawbar you have to cut it anyways. $135 for a prebuilt pdb and you don’t have to fiddle with the fingers or palm anymore not like me worry about harmonics traveling down to the work piece.

Uguessedit · Jul 14, 2018

I was contemplating machining a drawbar for my one mill it’s only 16” oal long and little shorter than the norm. I decided on 304 stainless threaded rod. 6’ section shipped was $30 so I was left with extra for future needs plus I could make it so I could add an adjuster nut for the difference between some of my tool holders that have various thread depths so adding a power draw bar to this mill won’t be a problem anymore. Otherwise I had been swapping out spacers 3-4 times a day and that gets old too. Should get 3 draw bars out of that one six foot section. A lot better than the Home Depot $5 threaded rod which if needed you can always do in a pinch. Better than waiting a week to order a drawbar and not running your equipment.

tdmidget · Jul 14, 2018

You have Home depot in Uganda? Only an idiot would use 304 for a drawbar.

Newman109 · Jul 14, 2018

SND said:
4140, cheap and easy to get.

My Webb had a quick change unit that I removed since it didn't come with any collets So when I refurbished it, I had to buy or make one. I had some 7/16" 4140 rod so I just threaded one end 7/16-20 about 3" and welded some 3/4 hex stock on the other end after measuring.

I would be easier to buy one however.

thermite · Jul 14, 2018

tdmidget said:
You have Home depot in Uganda?

Seems so:

The Ky Home Depot Uganda Ltd
Construction

Building and construction materials
Food, beverages and related products
Office equipment, stationary and consumables
Plumbing materials
Electrical, plumbing and other construction installation activities
Construction of roads and bridges
Specialty:
Supplies
Registration Date:
Jan 28, 2015
Phone Number:
+256752436512
Email Address:
[email protected]
Location:
Kampala
Kampala District
Uganda

And nooo, SS is not a wise choice atall for threads that have to "just work".

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