Steel recomendations for bandsaw axle

That's how I fixed a 10" Delta, drill rod and new bronze bushings.

jsw

4140 would be a good choice. Normalized, it's machineable, if not quickly machineable, and has a yield of around 95 kips. You can more than double that in the oil-quenched condition, but single-point turning anything above about Rc 40 requires some good technique.

Chances are that the normalized condition will do it for you, but if M-C has some medium-tempered steel, you might try that if you have a rigid lathe and some carbide tools. Just take it slow.

Here are properties of various 4000-series alloys. Those are good choices for all but the most extreme applications. Good luck.

I'd use "Stressproof," which is a tradename for AISI 1144. See the bottom of McMaster p.3605. You'll have to start with an oversize piece if the 1" dimension needs to be close to 1.000.

My second choice would be 1045 TGP (turned, ground & polished), but only if starting with an accurate OD is a help. McM p.3601

If you want something even stronger, you could use 4140 pre-hard, but at the expense of stability and machinability. McM p.3609

Was the shaft ever hard? Try filing the end remote from the TIG brazing.

There is a good chance that the shaft is ordinary mild steel, as Delta was making these by the million for small dollars. If mild steel, a leaded steel (like 12L14) would work dandy.

Touch the old shaft to a grinder and look at the sparks. This will tell you if the shaft is alloy steel.

Joe Gwinn

I used normalized 4140 for swingarm bushings for my motorcycle . Slow speeds , light cuts , and normal feed rates . Dwell in one spot too long and you'll be grinding the hardened layer off you just created . I used very sharp M35/M42 in a lantern toolpost on an old Logan . Finishes beautifully ...

The original shaft from my 10" Delta files and sparks like mild steel, and the pulley setscrew dug deeply into it. The end shows that it was cut to length with a bandsaw.

You could make it from solid drill rod the size of the bearings and sleeve the pulley bore on the large end. I found out the hard way that drill rod needs annealing after a TIG weld.

jsw

Yup, that's been my experience with it, too. I use it because I happen to have a couple of bars of normalized 4140 that were given to me, and I've used it for a number of little shaft jobs, turning it with what is probably M2 -- my ancient stash of Crucible Rex (no number) -- on a 64-year-old South Bend 10L, with a rocker (lantern) toolpost. It cuts nicely.

I've also machined pre-hardened 4140, but that was on an old Reed-Prentice lathe with carbide cutters. My SB and I don't do very well on steel harder than Rc 40 or so. I've managed it a couple of times, but not reliably.

Anyway, that's a pretty strong steel, and it makes a good high-end solution. Others have recommended Stressproof, which is extra-hard-drawn 1144 with a stress relief heat treatment. It has about the same yield (around 100 kips) as normalized 4140 but only about half the elongation. Better elongation is the primary advantage of 4000 Series over other carbon steels, but it shouldn't make any difference in this application, because if it takes a permanent bend, you're screwed anyway.

I'd use whichever of the two is more readily available.

Bingo. I suspected as much. It's cheaper for Delta to make this part big enough that ordinary steel is good enough, so that's what they did.

There are lots of alloys used to make drill rod, and some are air hardening.

I would just make the new axle from 12L14 (which is a bit stronger than ordinary mild steel like 1018), and put the money and effort into good bearings and accurate fitting to the shaft, so no repeat drama.

Joe Gwinn

Cabinet shop I useta work at got a new CNC router (4'X12' bed) . I ended up with three pieces of (pretty sure) 4140 that were 2 3/8 to 3 1/4 dia and

6 ft long ... They were part of the shipping bracing ... this stuff throws a spark identical to known 4140 , and hardens exactly like it . I've used about 2 feet ...also got some 3/8" plate brackets an' stuff , same material . And about 20 feet of 1 1/4 rebar ... hey , ya gonna throw that old chunk of metal away ? Well , throw it MY way !

Is 41L40 much different that 4140? Reason I asked, is I ordered a piece of that to make something and got impatient when I saw it wasn't going to make it to me until

1/4/2010. I really hate turning 1.25" dia stock into 9/16" dia stock but I didn't feel like waiting. 12L14 is a joy btw.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

'Don't know about it, Wes, and I've never machined it. If it's as advertised, it must be something like 12L14 is to 1214.

If you try it, please let us know how it is.

I forgot to mention that part. Oilite bronze bushings compress when pressed in and probably will have to be reamed to fit. IIRC I pulled the reamer through, with centering shims (tape?) around the shank, so the two holes would line up.

Reamers don't always cut well backwards. The 5/8" one I used had been ground on the shank with a round-edged wheel that left enough of an angle on the back end of the flutes to self-center. I have others that are almost square there and make a mess backwards.

jsw

I'll thread another tool post stud for grins after I get it. Will post a followup.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

Thanks all for the responses. Quick too! I ordered up a piece of 1144 (stress proof) 1.25" diameter. 1" would have been nicer, but I assume tolerance= -0.006 means the piece is smaller than what I need. I checked out all the other steels recommended and "fair machinability" scares me. This shaft has three diameters, and is threaded in two spots. Did I mention that i am a wood guy? I really like this saw however, and will give it my best shot to get it running again.

I took the old shaft to the grinder, and the sparks were more "fireworky" than a piece of steel pipe. I assume this means it is an alloy steel of some type. A file cuts into it easily, so it is not hardened.

Luckilly there was not a lot of drama when the shaft broke. The blade fell off the machine while cutting, and when I tried to re-mount it, the upper wheel broke free.

I will take some photos and post my replacement shaft.

Thanks and happy new year!

Andy

The 4140 is a useful material to have around, and it's especially good for transportation machines, like your motorcycles. The extra elongation makes it safer in applications where it might be loaded to failure, as in a crash. You can get equal strength in plain carbon steels but not the elongation, which is another way of saying it has good ductility.

Even though it has only 40 points of carbon, it will harden and strengthen as if it had a lot more. That's the result of the chromium in the alloy.

I don't visualize what you need to do. Nor did I realize that the bearing is oilite. Or was it solid bronze or babbit metal? These are stronger than oilite.

I would think one would be using a hand reamer. The adjustable ones would allow one to creep up on the dimension. I recall from old books that people used a reamer with a long shaft at one end and a T-handle at the other, plus a bushing that went into the other bearing and accepted the long shaft, ensuring that the two bearings were lined up correctly after reaming to size.

While I have not seen such a reamer in present-day catalogs, I haven't looked either.

Joe Gwinn

Ok, if it's Stressproof(tm), and not just normalized 1144. Stressproof has a yield strength of around 100 kips (thousands of pounds per square inch). Ordinary normalized 1144 yields at 58 kips.

That probably will do the job, but if it isn't Stressproof, it's not what you may think you're ordering.

More sparks generally mean more carbon. Alloys, in general, make fatter, less-sharp sparks.

Although some folks here will disagree, my guess, based on some materials experience, is that the original is a piece of cold-rolled, medium carbon steel. The most likely grade is 1040. That's a very common steel for mass-produced parts that have to withstand a medium load. It's probably the most common steel used for machinery parts, and it's even used for things that we think are very demanding, like the shafts on McPherson struts.

As a rule I go upscale from what I think the original is, if I'm machining a replacement part for something. 1020 may do the job but I'm not going to machine a part twice to find out, when I could have used stronger steel and done the job once.

Happy New Year to you, too, Andy. And good luck making the part!

This is a machine reamer with a setscrew flat on the shank. I turned it by hand with a Crescent wrench. It was second hand and may have been modified to go on a turret lathe. It wasn't meant for the use you described but it worked.

The shaft could be turned to fit after reaming, or even turned small to the unreamed size. It's much easier to fine tune the shaft diameter with a lathe than the hole size with a reamer. I assume the bandsaw has pressed-in bronze bushings like mine since the shaft looked similar.

jsw

If I picture this, you used the long straight shank of the reamer (plus a bushing?) as the pilot shaft in the other bearing to ensure that bearing being reamed lines up with pilot-shaft bearing?

That was the implication, and the pictures of the upper axle tend to support this. Too old to be built with ball bearings.

Joe Gwinn