How the pros do it: line-boring on the lathe

[Forrest Addy]

Links to this set of videos have been posted before but I think they are worth revisiting. They superbly illustrate non-exacting work in progress in the good home shop/small commercial shop operation. Quite literally, guys: this is how it's done for profit on the small scale.

Caution, the vids run for 30+ minutes apiece.

Super Shaker - YouTube

http://www.youtube.com/watch?feature=player_embedded&v=8qFl67ByDfA

Super Shaker 3 - YouTube

Super Shaker 4 - YouTube

Super Shaker 5 - YouTube

The job - fit a shaft to a bearing and line bore some structural tubes to fit - is fairly simple but presents a number of challenges and questions. Kieth Fenner's running commentary is complete but relaxed. It's plain old common sense applied with an eye to efficiency and timely completion. Kieth spent a bit more time than I thought necessary building apparatus but as he comments he's a fellow who works with the future in mind.

Kieth's presentation is competent and assured and the equipment he uses is straight forward and simple. His methods and judgements suit the work to be done. You noobs looking for an example of shop work and general comportment could do worse than watch this video a few times to pick up a few pointers.

You more experienced people will probably have some interesting observations on the presenter's methods and possible alternatives.

One thing Kieth skips over is the technique of accurately transferring a bore size to an inside spring caliper when the bar is in the way and the how to mike the size. His demonstration for the use of a telescope gage (he calls it a "snap gage," the rube) is excellent but no info about using an inside caliper for diameter checks around a boring bar which is a critical step in his process.

He employs lots of other cool tricks too. Maybe a few of you will spot and list them. I liked using the air hose to blow cutting oil off a dripping brush into an obstructed bore. I've done that with a pump oil can but the brush trick is a plain clever alternative.

 

[kapps]

I found that series on YouTube last month and ended up staying up way too late one night because I wanted to finish all the videos. Definitely well done.

 

[omrc7771]

Time well spent watching any of his videos. Mike

 

[dazz]

It takes a reasonable amount of time to produce videos like these.
I wonder who paid for the time he spent moving the camera around and giving his explanations??

 

[omrc7771]

I've had some conversations with him, He is a one man shop...the owner. He pretty much does it because he is passionate about getting younger guys interested in the trade. He is currently putting together a Kennedy machinists tool box, loaded with tools, to give away to viable candidate. Super nice guy. He is paid by YouTube for his vids - they call it monetizing. It's based on adds on the vids and # of hits. I think the guy is an outstanding teacher and machinist. Mike

 

[Forrest Addy]

I searched for "Kieth Fenner"on YouTebe and OD'ed for about 3 hours. He's posted a ton of machine shop related stuff, all lengthy and detailed. While a few of his methods make me cringe (Emery cloth on Babbitt? Come on!) the other 99% are right on target.

He could don safety glasses when grinding, though; makes a good impression.

 

[oxford]

There is only thing I wonder, and I guess it didn't matter since he didn't do it(or maybe I missed it). When he had the boring bar in the lathe how did he know that there wasn't a belly in it under its own weight? You would think you would want to get that set with a steady rest close to the center then dial in the bar to the OD of the tube. Once his bearings were in place you could have took the steady off and they would have held it in place. Depending on how tight the bearings were made of how much belly it could have started to bind when moving.

 

[Forrest Addy]

There is only thing I wonder, and I guess it didn't matter since he didn't do it(or maybe I missed it). When he had the boring bar in the lathe how did he know that there wasn't a belly in it under its own weight? You would think you would want to get that set with a steady rest close to the center then dial in the bar to the OD of the tube. Once his bearings were in place you could have took the steady off and they would have held it in place. Depending on how tight the bearings were made of how much belly it could have started to bind when moving.

Yeah. That jumped out at me too. If the bar could simply sag and a heel-dragger tool used with all the other clever HBM tricks the bore would have been straight as the lathe bed. Add mounted support bushings and the project gets complicated.

I would have dialed in each end having run the carriage up near the chuck or tailstock as appropiate. Use the bushings to support the bar agaist the sag to ensure the tool orbit is as close to the spindle axis as possible.

2" dia bar 6ft+ long? I figure he sag - was it a 2" bar? -would be roughy 0.060".

 

[Matt_Maguire]

With the bar chucked at one end 1/64" would prolly be the max bar sag & moved a bit towards the tailstock. It's tubes for a large hinge so no harm done there. Keith is pretty much the real deal for a one man repair shop and has good habits, except I can do without the compressed air blowing chips off machines - it just means I gotta sweep a larger area before I'm done...

True enough, with that setup having the bearings fixed to the part and the bar fixed to the saddle it's not an ideal situation unless you can steady the bar at each end while indicating the tube & fixing the bearings to the piece part. He seemed to do pretty well with what he had at hand.

Now when he was sweeping the indicator around adjusting for "0" at 3-6-9-12 o'clock - IS a problem. Next time any of you fellas got a bar in a chuck or V-block set & zero it at 12 then roll the bar over to 6... Whenever you intend to use an indicator like that you should reference the indicator droop as you are going to use it. It's not unusual for a 1" travel indicator like that to read .004-5" different from 12 to 6 & even the really good DTI's move some. The more junk you clamp together between the base & the indicator the worse it gets.

I subscribe to Keith's channel BTW & enjoy catching up every once in a while on what he's up to. It's good for the hands here to know he's out there, "thanks Forrest".

Matt

 

[traditional-tools]

I searched for "Kieth Fenner"on YouTebe and OD'ed for about 3 hours. He's posted a ton of machine shop related stuff, all lengthy and detailed. While a few of his methods make me cringe (Emery cloth on Babbitt? Come on!) the other 99% are right on target.

He could don safety glasses when grinding, though; makes a good impression.

I have watched quite a few of his videos and most are very good. I hadn't seen this series though, and this was a long one with the 5 x 30-40 minutes each.

This was very good though and well worth the watch. Thanks for posting the link to it Forrest!

2" dia bar 6ft+ long? I figure he sag - was it a 2" bar? -would be roughy 0.060".

I thought he measured the run out on the boring bar in the beginning and it was only about .002", but your number is much higher for sag. How do these relate?

Does the sag only become evident with a load on the cutter?

His jig basically puts a steady rest on each side of the pieces being bored (the first was longer, and then the 2 smaller sections on the ends). Wouldn't the sag be calculated for that distance rather than the full length of the boring bar? (i.e., his bronze bearings would support the boring bar between that distance)

Cheers,
Alan

 

[Forrest Addy]

Run-out is a radial measurement of a bar's departure from a true axis of revolution. Sag is the deflection due to gravity, the material's elasticity and proportions, and gravity.

The stiffest beam supported by the ends sags some small amount from gravity. Alonder slenderer beams more so until the materials slastic limit is reached and the member droops from between its support, permanently bent.

 

[Roger Williams]

Hello, I couldn't agree more about Keith Fenner, his videos are marvellous. I like his methodical approach, letting viewers know of his every move. Top bloke, and first class instructor. Regards, Roger.

 

[traditional-tools]

Run-out is a radial measurement of a bar's departure from a true axis of revolution. Sag is the deflection due to gravity, the material's elasticity and proportions, and gravity.

The stiffest beam supported by the ends sags some small amount from gravity. Alonder slenderer beams more so until the materials slastic limit is reached and the member droops from between its support, permanently bent.

Forrest,

Wouldn't the 2 supports on each side of the work limit that sag? I understand what you're saying, that essentially the run-out is how concentric the bar is, vs the deflection/sag along the lateral...but doesn't the 2 supports create a much shorter length due to the support/weight distribution? Which is to say, the work being bored is essentially supported and that would appear to be the limiting factor in deflection of the boring bar. His jig essentially shortens the suspended length but since the end caps holding the bearings are solidly attached, it seems the boring bar could only deflect within that length of the work which is between the bearings. Even if the boring bar has defection/sag, it will be secure to the lathe compound (through his jig) and the bearings keeping the boring bar spinning true. So if there was defection/sag, it seems that would be distributed to the boring bar on both sides of the work, external to the bearings.

Maybe an easier way to state this would be that the jig which is attached to the compound appears to be limiting the amount of sag that can occur.

OTOH, I could be over thinking this...

Cheers,
Alan

 

[Peter.]

Nope, because he indicated the work concentric to the bar with it already in sag.

If he had indicated the bar parallel to the ways and supported it on steadies before indicating the work to it then the bar would be supported by the bearing caps once the steadies were removed.

 

[tailstock]

At the end of the last vid you see the finish product and it works, what more do you want. This is job shop stuff, you know there will be sag and run out but you adjust and live with it, no time to sit and stew about it. Knowing what your fit must be at the end +or- ? makes a big difference in turn around time, If you have the room to wiggle a bit then go for it and get the job done. Not saying you don't have to stay within spec, just know what you can get away with and carry on.

 

[traditional-tools]

Nope, because he indicated the work concentric to the bar with it already in sag.

I just went back and see now that he just takes a few readings along a section, and only has about half of it out of the chuck.

However, the jig still seems to support it, and he does tune it so that there are no harmonics, seems to spin pretty true in that regard. It just seems if he was concerned about the sag he would need to check it with the jig attached since that is what attaches the sleeve to the compound.

What he didn't show is what he did when he heated the bar to get it within .003", but it seems that he did some work with the bar before putting it on the lathe, heating up one area to bring it into alignment was one.

What would you do different ? I know there are many ways to skin this cat, so just curious what you (or Forrest for that matter) would have done differently.

Keep in mind he clearly states that they will weld those sleeves together when they manufacture the boat, and that will cause the sleeves to distort also. They ain't building a rover to go to Mars...:-)

Cheers,
Alan

 

[ARB]

It's interesting. I was sick a couple weeks ago and rode the couch for a few days. I discovered Keith's videos then. I found them pretty fun to watch. I even learned a few things.

I agree that he generally does a great job. He has some handy tools and kinks to make his work go well.

I like his hydraulic press set-up and that drill press is pretty nice too.

It is nice to see a man with the passion and experience that he has taking the time to make these videos for all to enjoy and learn from....

Nicely done Mr. Fenner.

 

[Peter.]

I would do nothing different at all for the application, but bear in mind I'm not a machinist. I was just commenting that the end caps aren't limiting the sag, just working as dampers. If anything they will serve to increase the sag as the work travels towards either end because the bar ends being held higher above the bed than the place the part was indicated. This is borne out by the observation that the end cap moving towards the chuck started holding oil in the oil well and the one furthest away was passing more oil as the work travelled.

If you wanted to have the caps support the bar on-axis you would indicate the left one near the chuck and the right one near the tailstock or support the bar before dialling the part in.

 

[omrc7771]

I agree with Forrest about polishing babbitt bearings with abrasives, that was very out of character for him as he usually does everything best practice. I have a huge amount of respect for the man as he is alot more versatile than 95% of the journeymen I've worked with. Granted, he has the ability to edit, but as far as I am concerned he is the king of setup -fast,efficient, knows exactly what needs to be done and doesn't over-think things. His press is his design & build, he can pour babbitt, he's a whiz on his plasma table, an outstanding welder, on and on. How many guys do you know that are that good at that many things? Anyone can learn something from his vids. Mike

 

[oxford]

What would you do different ? I know there are many ways to skin this cat, so just curious what you (or Forrest for that matter) would have done differently.

Cheers,
Alan

Not that I would do anything differently but the way I saw it there is a potential for a problem. Obviously there wasn't or there was some things we didn't see. He had the boring bar in the lathe between the chuck and the center. I am going to assume that there was some sag in the bar, lets just say .020" in the middle. He then had the tube over it to get bored and got it concentric to the OD of the tube. The head stock side should have been very close but in the middle would have been down .020". His bearings are locked in now and keeping things round with each other and the cutter doing what it needs to do.

What happens though when the tube starts to travel to the tail stock? If his tail stock center is in alignment with the headstock that .020" is going to have to go somewhere when the tube travels down there. Like I said this didn't cause any problems that we saw this time and the job go finished with the expected results but the potential for a problem is there and the risk goes up with how much the bar is sagging in the middle and how tight the lathe is. If the bar was set up with no sag in it then the problem goes away.