Thread: Making a Drawbar

Originally Posted by PDW

First I machine the solid round into a hex bar, then I turn the hex section back to round at the diameter needed for the spindle bore (except for where I want the spanner to fit), then I screw-cut the end to whatever thread I need.

Tisk, Tisk, Tisk. Every one knows you should forge the round bar to make the Hex. Its all about grain flow man.

Originally Posted by Machtool

Tisk, Tisk, Tisk. Every one knows you should forge the round bar to make the Hex. Its all about grain flow man.

That's why you're an expert, Phil, and I'm only a metal butcher with aspirations of competence.....

PDW

Originally Posted by PDW

Personally, I never use anything except Aquamet 22. First I machine the solid round into a hex bar, then I turn the hex section back to round at the diameter needed for the spindle bore (except for where I want the spanner to fit), then I screw-cut the end to whatever thread I need. Of course, to get a perfect thread form, I use nothing except those special carbide threading tips.....

Oh, you don't use the damascus, forged from billet, Aquamet? Well, there's ya problem!!!

You guys just arnt considering the environments that the drawbar is going to be subject to. For that reason, I plan on making my next drawbar from inconel, forged and then Ill hand scrape the flats on the hex, just to make sure it makes consistent contact with my supatool spanner. If its worth over doing, its worth over doing well!

Just make sure whatever you use it is from military grade aerospace billet..

But seriously, the only special treatment my drawbars get after making them is I put the skinny portion in the lathe and make sure the hex portion is square to the shank...

Here are some I have made, from the elaborate to the downright quick and nasty... All work well....

20150718_175133.jpg

Personally. I like to take a bit of 4140, Some EN36A, A bit of 8620 and some P20 just encase I want to nitride it. Then I fusion weld them together, forge them, turning them over until I have 300 layers of Damascus Rod. Then I make a Drawbar.

I'm putting a footnote, in this thread. Too many jokes Bro's. We are at risk of shoehorning the O.P bloke. And offending B.T

You can use any thing from Bunnies 4.8 grade all thread, threw to the example of B.T in 4140.

You will never exceed yield strength, as pointed out buy PeteF. I can't recall any of you blokes snapping a drawbar??

Harder / tougher is nice. I particularly like a drawbar that doesn't mushroom when you give it a tap.

3rd Hand Phil.

No-one has mentioned nitrated titanium?

Anyone, anyone???

Ken

Originally Posted by neksmerj

No-one has mentioned nitrated titanium?

Anyone, anyone???

Ken

Is that helping??

The other thing to point out in all seriousness is that if you're banging on the drawbar it means it's self-locking taper on the other end of your percussion instrument. That being the case it doesn't need, nor should it be, over tightened. The self locking nature of the taper means it is that which is doing all the holding, and all the drawbar is doing is stopping the whole lot from dropping on your toes. I think many people unnecessarily over-tighten things like MT3 tapers thinking they're doing themselves a favour, when in fact it just makes them difficult to get out, giving the bearings hell in the process.

Originally Posted by Pete F

when in fact it just makes them difficult to get out, giving the bearings hell in the process.

Absolutely true, any whack, neutral d-force, f-ing down, all opposed, any direction that's not good for bearings,

Originally Posted by Pete F

Agreed, nothing wrong with using 4140 if that's what floats your boat, but I see no reason to use a high tensile steel in something as mundane as a a drawbar. You don't get anywhere near the yield point of the steel, even the cheesiest black bar. I can see the potential argument about the threads if you're using the bar incorrectly, but the drawbars only need to be backed off a few turns, then whack the top to release the taper and then continue to undo them by hand. I've never deformed any threads and I've whacked on some bars far harder than I'm comfortable with considering there's some precision bearings on the other side of the equation!!!

When I make drawbars I normally single point some threads on the end of the appropriate size rod and then bore some hexbar for the rod. I've found by case hardening the hexbar it isn't damaged by the hammer, although I have copper hammers these days for stuff like that. I just Loctite the hexcar to the rod with stud lock. Brazing would obviously be better but I haven't had a drawbar head secured by Loctite come off yet.

Pete,

Whilst I had some 1214 that would have done the job my material choice was based on a strong dislike of the so eager to rust quality of 1214 and because I also had some appropriately sized 4140. The original drawbar is hard(ened?) and ground. Is is also machined precisely to fit into the 30 taper spindle nose to facilitate the use of P20 collets which can be inserted in the opposite end of the spindle - https://www.woodworkforums.com/showth...08#post1167408

Making my own from scratch allowed me to replicate the 22mm AF head dimension of the original. In my mind one spanner beats four.

As far as removing arbors goes, the 30 tapers I have vary. A couple of seldom used CTC chucks require a drawbar tap with a hide mallet, the often used Schaublin and the superb Rego Fix chuck come out with a thump of the hand. 3 Morse arbors come out easily enough if their installation hasn't been overzealous. A bit like screwed on lathe chucks. When I acquired my little Hercus mill someone must have used that three foot pipe Richard described on the end of a spanner to tighten the horizontal arbor drawbar. It took a puller, a pusher and heat along with some nasty language to get that out!

Bob.

You blokes should ask as to 1045. Its a poor man's 4140. Its not that exotic. Decent Steel merchant should be able to supply it.

Originally Posted by oohsam

Hi Guys, I need to make a draw bar and just wanted some tips. It seems very straight forward, but I have a few options, wondering if I can get some expertise on the best way forward. My draw bar is currently an M14, but most of my tooling is M16 so I need to make an M16 threaded draw bar. Option 1 is to purchase some threaded rod, M16 and weld a Nut to the top of it Option 2 is to purchase some oversize Mild steel (too soft?) and turn it down on the lathe, and cut the thread into it, and then Mill the hex/square head onto it. Cheers

Option 1 for me works ok last 30 yrs The nasty taper of Morse tooling beds them in tight and can be a right frustrating event to crack the taper. A few years ago I made a double forked tool similar to a ball joint separator for car suspension some a hammer and some screwed. This simple device is 2 opposed similar wedges that close up under the tooling held in taper as they intersect the width increases a tap or two on the draw bar and another nip of the wedges and out they pop. No shock loads for bearings and makes the job easier got a shaper mill can be made up in couple hours out of your scrap bin .No rocket Science involved.

Here is a pic of a couple of drawbars I use. One is M16 the other 5/8". Very simple - just a nut welded on the end with a loose locking nut and a loose collar to centre the drawbar. Also shown is the hammer I use to (lightly) tap out the drawbar after loosening the lock nut. Note that the mushrooming of the hammer head was done by the previous owner before it came into my possession (doing what I do not know).