Welcome, nice to have you aboard. Someone mentioned another similar but different indicator, see comment below. Has me very curious. Even the cheaper version I have is still pretty darn fun to set things up with. Lived without one for rather too long.

Very interesting, I’ll look into that for sure. Always like trying something different. Hopefully I’ll try it soon and can make a video about it. Thanks for the info.

@@TangentJim yup, that sounds fine. How one adjusts the tailstock to centreline is up to the individual, think of it like an ice cream parlour with many flavours. The method describe in my video is just one of many, a take it or leave it dish in the smorgasbord. I like it because I can generally get to perfection in three or less adjustments, generally two, but sometimes even one. The make an adjustment then sweep methods is fine too, but more like lawn darts or pin the tail on the donkey rather than a calculated adjustment. Thanks for watching and commenting.

Benno - Your saying is going to bite you . " Indicate or Assume " You used a Three Jaw Chuck and assumed that the shaft was running True . -- Jim

@@TangentJimtrue, ahh ,untrue, ahhh yup. Agreed. Give it a roll and indicate to verify and or take steps mitigate/correct. Good point.

Benno - You are a Bad Boy . You didn't follow your own advice . I'm giving you two demerits . -- Jim

Right on, always nice to hear of success. If you have time look up “Tangent Jim sine bar”, lots of great videos and ideas there. If you do a lot of that sort of thing buy one of them whenever you can afford it. In the mean time, until it shows up, you can set angles the trig/math/tear your hair out way, search “lathe compound setting”, there are a few good videos there for sure. I have a couple ideas to add, including the lack of reference edges on the machine, and dealing with poor machine set up, but that will have to wait until I can make a video on it. Have a great day.

Thanks Jim, don’t have collets for the lathe, Also the material is 1.5” dia. 4 jaw to the rescue? Not always worth the time to change chucks though………..not a space ship………haha. Maybe they used 3 jaw chucks at the space ship factory lately to make helium system flanges?

Benno -- Hey Jim " Nice Try but no Cigar " -- Jim

Great series of vids - some good refreshers for me. This one I particularly like because I hadn’t seen discussion of testing concentricity of a long shaft by turning two witness diameters. I like the approach - hope to try it at some point.

Stuart - This is not a contest - it's an exchange of ideas . It's about the easiest way to get there. We are looking for the path of least resistance . I'm sure that you have heard this line before . The shortest distance between two points is a straight line. We are looking for the straight line . -- Jim

@@TangentJim I understand. I apologize because I meant my comment to be a standalone note of appreciation for the video - and not a challenge to your excellent comment. I didn’t realize I was posting a reply to your comment - so apologies again. No argument intended. By the way, just subscribed to your channel also and am learning plenty from your content also.

@@keithjurena9319 ya,a cnc cutting table would be nice, not at this place for a few years yet I’ll bet……we’re very “traditional” (stuck in the past). Thanks for the comment.

@@OgiveBC I hear you! That CNC burn table started out as an optical eye system which traced over drawings to make the cuts. It was a pantograph type system, I forget the scale

Yup, that could work for sure. I’d still indicate along the part if I was turning along then length, indicate vs. assume.

Benno - In my previous comment . I forgot to mention one thing . Place the faced and center drilled Plate into the Four Jaw Chuck and indicate gently . Now insert your ball bearing center into the center drilled hole of the small end - it should run dead true . Now tighten the Plate side and indicate - again. Both ends should run dead true. Now indicate the total length of the shaft -- to see exactly what you have . Between the indicated ends you will find out if the shaft is straight or bowed . Indicating will tell the true story .The indicator reading will dictate your next move. If need be -- you can cut a diameter to accept the steady rest. Does this make sense ??? -- Jim

Yup, sure could be done, one consideration was the bolt recess on the stock one is not right in any dimension. Also on my new one I’ll round both opposite corners some day and it will just drop in anywhere. Don’t want to chop the corners on the stock one.

The taper section of where the propeller mounts is pretty well plus/minus zero on the angle, ends up getting checked with Prussian blue and hand lapping if out. The small end of the taper is about plus 0.002, minus zero depending on the shaft size. The area of a shaft under a liner/wear sleeve is not so much critical on exact diameter but it has to be cylindrical, that is no taper for the liner length, say 2 to 3 feet. The ID of that heat shrink liner should be within a 0.001 end to end, preferably less. The OD of a liner is more a matter of pride than regulatory/rule. Say plus/minus 0.005” over the liner length not a big deal but always strive for less than about 0.001-0.002” so if anyone checks later they don’t think poorly of the last guy to work on it…………..if there is more than about 0.005 runout (depends on roller spacing) any anywhere due to a bend, it gets straightened.

Interesting, never heard of it, just looked it up. Thanks for mentioning it.

Have not seen those before - a very interesting tool and a simple approach to the situation. Would not be too hard to make one if someone really wanted to.

@@StuartsShed Would not be too hard... First, let's take into account the "Hierarchy of accuracy" in measurement. You want to make something which indicates within reasonable accuracy to "tenths" (0.0001", or tenths of a thou... the equipment you make it upon, and with which you measure its components, must be made with components produced to considerably tighter tolerances) Many moons ago, we were led to believe a precision instrument components must be measured using a precision instrument that was made to limits a tenth of the width of those being produced... (it's not entirely true, but it's indicative of the necessity to measure precision instrument components with more accurate precision instruments...) The history of accurate measurement in engineering is an interesting one... We've been able to gauge (different, I know...) to millionths of an inch. Microns are 40 x a millionth of an inch... The history is fascinating... and yet, you'll find places where they have jig borers and standards departments with no temperature control... I knew a guy who worked at a place making parts for submarines, on a jig borer... "constant 20C, then?" I said... He had no fucking idea... worrying!

It is a “First” brand also might be known as “Long Chang”. It’s a Bridgeport clone with a NST 30 spindle. I kinda wish it was R8. Oh ya, and a Bridgeport.

You’re a philosopher. I very much liked your comments around what is known about the past, present and future states of a part. That is the very essence of reverse engineering. I shall work my way through your videos. Thank you.

Yes, it’s for a river style tug that has two propellers in fixed Kort nozzles and each propeller has two rudders aft of (behind) it.

Hi Jim, if the lathe is pretty straight and level your way will work like a hot darn, also it requires that the workpiece is less than a couple hundred pounds I believe. If the lathe in question is as out of true as my big one, the axis of the headstock spindle and the bed are two rather different realities. I’ve tried all sorts of ways with heavy parts, indicating off the chuck face to the part, mount an indicator on the tailstock end of the workpiece and indicating off the tailstock etc. any way that gives you a not tapering part (unless that’s what you want) is a great way.

Benno - If the lathe is pretty straight and level your way will work like a hot darn. I reject that statement . How does your method make the Lathe Bed True ??? --- Jim

It does nothing for the bed of the lathe, and I apologize if I said that it did. It allows you to get a segment length of the workpiece parallel enough with a section of the bed that when you turn the diameter of a part, in that same area of the bed that was used to indicate, the inherent taper will be as minimal as possible without resorting to adjusting the cross slide setting during the length of cut. Very long cuts will still be a big problem. One that is proportional to the twist in the bed………..of the lathe.

Benno - Again -- Indicating both ends would accomplish the same thing without the complicated math . I suggest you try it on one shaft -- Jim

⁠thanks Jim, I’m very familiar with the method you describe. I’ll be making another video about this subject soon. Thanks for the input and stay tuned………

Thanks Jim, really appreciate it. More to come, I just found out that I didn’t hit record on a segment for the next video instalment. Unreal. I’ll have to reshoot next week. I was filming late in the day, late in the week, wasn’t running on all cylinders……..

I think when I tried to reply earlier I posted instead of replied perhaps. Someday I’ll learn which button to push?

Funny how when one builds something, you never say later that you wished you had delayed the building/doing……

This is the first time I have tried with a full length bar. I had a hunch but no mathematical proof. Will do an answer video soon. Thanks for commenting.

Welcome from Canada! My grandparents on one side of the family came from the south part of your country. Thanks for the great reply, sorry about the imperial units. I’ll do an answer video soon. Almost all bar stock here is supplied in 20 to 24 foot lengths. Would an increase in diameter and not length result in a same better or worse condition? Also we have several forklifts and the one shown in the video has the shortest forks, the larger has forks at least twice the length, so would lessen the bending moment a fair amount. Not how we usually /ever handle material however. Thanks again for the comment.

Wow learnt new things today

@@OgiveBC Oh very nice! I'm actually originally from South Africa, but have been living near Amsterdam for 2 years. So I went ahead and simplified it for you. The following calculation is only really applicable for 1045 steel as other steels might have different densities and yield characteristics. But in a pinch should be accurate enough for most kinds of steel. Use the equation: Stress % = 46 * free length^2 / Diameter With it you will be able to calculate the stress in round stock. The free length is the length of the unsupported section, in feet and diameter is in inches for your convenience. This will give you a percentage of yield stress. So if that stress % is above 100, you might get bending. Below 100% you will be good. So to answer your question. The longer the free length, the worse, the thicker it is, the better.

⁠I’m very impressed with the formula you have created. To me it is just magic that you could reduce a complex question to a simple equation. Thank you. When I make a final video where I put that bar on the rollers to prove it’s straight, may I show your comment in that video and give you credit for it? I’m sure some people would be amazed to see it.

Thanks for the comment, we usually move bars by picking them up from the middle with a forklift and the bar sideways, as I’m sure most people do. I’ll do an answer video soon. Good point about the sling, it would see a lot of strain. As to the bouncing while driving…….could get interesting