Topic: Can any lathe masters tell me what I am doing wrong?

[trueblue]

My center drill merely polished the end of the shaft to show where the center would be if it had actually made the cut.
I slowly increased the pressure to get a cut started and the tip broke off the center drill... same thing happened on the second try.
I tried a center punch and it flattened the end of punch.  I guess the steel is pretty tough. 

I did sandpaper the shaft so the main m bearing now fit.  Now the task is to get the rod pin to again sit parallel to the shaft.  The pin is pressed into a round of brass about 1/4 thick.  The round has a set screw to lock to the main shaft.  However, that mount surface is now rounded, and this kants the rod shaft.

I think I may go back to building things electronic or stick with wood projects. 

Cheers,

If you can't cut it with a drill or even centre pop it, it is too hard to machine effectively, it needs to be ground, most engine shops should be able to do it.

[70CB750]

Any chance of tool post grinder?  Even rigged one from rototool would work.

I don't have a tool post grinder.  I expect I may still be missing routine and essential machine shop tools.  I'm my own apprentice.
Anyone make/sell a machine shop kit? 

By rototool, you mean a Dremel type?  I don't think the cutter bits have the "reach" to traverse the entire shaft length on a parallel axis.

Cheers,

Yes, the dremel type would work too. I have seen even air grinder fitted to the post.  But people make more elaborate designs for the final finishinf or to take small amount of like you need to.
There is an excellent forum BBS Machinist with plethora of information and people willing to help.
http://bbs.homeshopmachinist.net/
I go there for ideas and to ask questions when I am lost.
Just the shop made tools thread is worth your time.

[70CB750]

Here is a picture, crude solution  - not mine - but it would work.
I only have old Logan lathe and I have to be creative to get things done.

Good luck.

[TwoTired]

Newsflash.
I've had these parts for 20 years and they never showed a spec of rust.  I made the assumption they were stainless without doing any magnet tests.
Did the magnet test today, and they are highly magnetic.  So, they must be some kind of hardened steel.  I guess I never let them go without a coat of oil, even in storage.

I'm going to have to rig up a grinder of some kind, me thinks.  I have a couple of Dremel tools.

However, before that, I have to overhaul the main power switch on the Smithy.  It's doing intermittent things, along with giving off that burnt electrical smell.  At least fixing that is something I have some expertise in.

Thought you might like to see what all the ruckus is about.  So, here are some pics of problem subject parts.
First pic shows the pump on the right.  On the left is the shaft recently reduced and mounted in the lathe chuck with the roller bearings in place on the shaft.  Rubber banded onto the chuck for the picture is what the crank and rod shaft looks like in proper orientation.

The second pic shows the problem caused by the rounded taper on the end of the main shaft.  The rod shaft is non-parallel to the main shaft by about .010 over its length.  Rod bearings won't like that.  Waiting in the wings (next phase) is the rod bearing switch over from single bush type, to twin rollers in each rod.  I'm certain the rod shaft must remain parallel for the bearings to have decent life and to prevent binding.

Cheers all,

[TwoTired]

If you can't cut it with a drill or even centre pop it, it is too hard to machine effectively, it needs to be ground, most engine shops should be able to do it.

Ah, but where is the "fun" of paying someone else to do it? 
And then, what will be the lesson(s) learned?

So, now I have another "domino" project", attaching an abrasive grinding tool to my cross slide bed.  I guess it is a tool I always wanted.   
Anyone know of published designs to get inspired from?

Cheers,

[754]

 Many ways to mount it, just make sure you cover your ways and clean it well
 Learned a cool trick on practical machinist.. they cover most of the machine with Saran/shrinkwrap.. works really good..

[david 750f]

You might have hardened stainless steel which would be magnetic. (Try the magnet test on stainless chef's knives).

Or it could be shafting that is surface hardened.

Either way it needs to be ground, try the emory cloth tip suggested in a previous post.

[scottly]

The second pic shows the problem caused by the rounded taper on the end of the main shaft.  The rod shaft is non-parallel to the main shaft by about .010 over its length.
Cheers all,

It looks to me like the rod pin is bent? Is it pressed into the brass flywheel? You can check this with a square.
The screw holding the flywheel to the main-shaft won't provide much holding power: you should replace it with a proper cupped end set-screw, and grind a flat on the main-shaft wider than the cup. (Without the flat, the set-screw will raise a burr, making removal difficult, plus it acts a bit like a key.) 

[TwoTired]

Many ways to mount it, just make sure you cover your ways and clean it well
 Learned a cool trick on practical machinist.. they cover most of the machine with Saran/shrinkwrap.. works really good..

Shrink wrap/cling wrap sound like a pretty good tip.  Thanks.

I think I have a way to make the Dremel do the job.  Work in progress...

[TwoTired]

Either way it needs to be ground, try the emory cloth tip suggested in a previous post.

I did. I used emory glued to a T bar.  Bearings go on now.  Have to fix the round over end.

[TwoTired]

The second pic shows the problem caused by the rounded taper on the end of the main shaft.  The rod shaft is non-parallel to the main shaft by about .010 over its length.
Cheers all,

It looks to me like the rod pin is bent?

Probably optical illusion/camera lens optics.  All five samples look the same on this shaft.

Is it pressed into the brass flywheel? You can check this with a square.

It IS pressed. ..And checked with a square.  It is square.  I still have an original main shaft to check against.   And, the rod shaft(s) remains parallel on that one.

The screw holding the flywheel to the main-shaft won't provide much holding power: you should replace it with a proper cupped end set-screw, and grind a flat on the main-shaft wider than the cup. (Without the flat, the set-screw will raise a burr, making removal difficult, plus it acts a bit like a key.)

If I were making one from scratch, I certainly agree with you about the set screw and choose another.  But, it is hard to argue with 20 years of trouble free function with the existing screw.  Makes me kinda lack incentive to change it.

Really, there is not much pressure on that rod shaft or crank.  The "pistons" use a leather rub seal in the cylinder, and have very light springs in the check valves.  The unit develops 4-10 PSI from the two cylinders, and can deliver air to about 20 aquarium air outlets.   It's just that they run 24/7, 365 days a year.  And, I'm getting forgetful/inattentive about the 3 month oiling schedule.  Further, i found out the hard way that the Bronze bearings should have had mineral oil.  All the brochure said was to use 20Wt oil, which I did. 3 in 1 20Wt oil, which I latter found out is paraffin based rather than mineral (costs less for manufacturer).  Paraffin dries out and turns "waxy" plugging up all the pores in the bronze.  The unit relies on oil flowing through the porous bronze to keep the rod wet with a surface film.  It has oil reservoirs/wick holding oil on the outside of the bronze bearings. Once the paraffin turns to wax, the oil flow from outside to inside through the bearing stops, and you have to re-oil the shaft at least every month or less instead of every 3.  If you don't then you get a rod shaft that looks like pics below.  This happened during my Hospital stay a few years ago.  To the pumps credit, it still kept all the fish alive.  But, the rattle was intolerable in a living space.  Anyway, mineral oil doesn't dry out and clog the pores of oilite bearings, as I found out too late.

The dream is that the roller bearings will make the service interval a yearly endeavor, and increase the pump's endurance, as my personal endurance wanes over the next few years.

Cheers,

[scottly]

With the square on the main shaft and flywheel, and the set-screw tightened,  can you see the misalignment?

[TwoTired]

With the square on the main shaft and flywheel, and the set-screw tightened,  can you see the misalignment?

With the unmodified main shaft, no.  With the rounded, tapered shaft from trying to reduce the overall diameter, yes.

[754]

 I would probably just make another shaft, if your chuck has any runout, it hard to do what you are trying and stay accurate, unless you polish it off.. up to .003 its better to polish it, most of the time.
 Did you try the centering trick?

[TwoTired]

Did you try the centering trick?

I didn't understand your instructions. 

If I lay a ruler on top of the work piece, the tool bit would be centered at an offset the radius of the rod.  That just can't be right.

[scottly]

Did you try the centering trick?

I didn't understand your instructions. 

If I lay a ruler on top of the work piece, the tool bit would be centered at an offset the radius of the rod.  That just can't be right.

Some pics may help...

[TwoTired]

Some pics may help...

Yes.  Now it makes sense.

Do most tool posts have a vertical adjustment?  I guess the Chinese don't need that. 

Must use shims on mine.  Unless there's a part missing I never knew about.

My tool post grinder is ready to try out (in the back ground).   

[ofreen]

Do most tool posts have a vertical adjustment?  Must use shims on mine.  Unless there's a part missing I never knew about.

My old Atlas uses shims.

[scottly]

The tool post that came with my lathe was just like yours, Lloyd. The tool post in the pics is a quick-change post, that mounts the tool in a holder that slides onto dove-tails on the post. Each tool holder has an adjustable stop, so that once set, you can swap back and forth between tools without readjusting height.
A lot of the old lathes had a "rocker"? type tool holder. They could be a real bear to adjust, because changing height also changed the angle of the tool.   

[70CB750]

Plus one on the quick change tool post. Spent 100 at Enco for a set right after I got my Logan. The rocket post gets used too, but for most work the quick change is great.

[754]

TT if your tools are hanging out that far, most of the time...its too far..

[TwoTired]

TT if your tools are hanging out that far, most of the time...its too far..

It's not that I don't believe you.  It just that I'm the kind of guy that needs to know why.

If I learn why, then I don't have to memorize facts and figures, etc., which can be found in reference material.  And, I only have to recall where that ref. material is located.

Anyway, I mounted them that way because the tool post has four detent positions, allowing four tools to be mounted.  Just seemed logical.  I'm still learning what tool is used for what operation.

Thanks,

[trueblue]

If they are hanging out that far, it will cause tool chatter, because the tool isn't supported properly.

[70CB750]

What true blue says. The whole system of product, machine and tool has to be as rigid as possible. Tool sticking out will chatter.

[754]

 Carbides are far more susceptible to chipping and breakage than High speed steel (HSS), and require different grinding stones. Brazed insert carbides dont always have a ready to go edge, they may work, but often can be touched up to perform better.
 2 Rules of thumb;
 Use  the LEAST amount of overhang on your tool.
 If work EXCEEDS 5 x DIA, it should be supported with a centre.
 
 I made this and used it thousands of times., Take a piece of  stock,say1 to 1.5 inch square or cut  4 flats on  round bar., about 4 -7 inches long. It must fit in your 4way. Mill a slot along the side for 1.5 inches(1/4 or 5/16 wide) and 1 ACROSS the end of the bar. Above that put in setscrew holes to clamp your toolbits. Now this tool will support your HSS bits with several inches of overhang from the 4 way, as it is a stiffer , more RIGID setup. I probably have at least 40 shop-ground toolbits of HSS that I use a lot, and more that I use occasionaly.

 I use the 4 way post mostly, my tool height of that is 7/8, so I can assemble the shims under the tool, and measure with calipers, then just put it in the toolp[ost and clamp...