5 Tests for Lathe Bed Wear - Complete Simple Methods
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- เผยแพร่เมื่อ 8 ก.ค. 2024
- This video highlights 5 simple and fool proof ways to examine a Lathe for bed wear. Make sure to watch this video before purchasing a used Engine Lathe.
2:01 - The Visual Inspection Method
3:54 - The Carriage Lock Method
7:10 - The Test Indicator Method
17:36 - Square & Flashlight Method
20:25 - Feeler Gauge Method
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Excellent tutorial and I agree, the best method of evaluation will be to conduct tests with the bed on a good surface plate.
I think in the end that’s the only true way to do it
Nice job!!
Plainly laid out and demonstrated
Thanks for watching and for the encouraging word! I appreciate it!
If you had a decently long scraped flat straight edge, you could blue that up and use it on the ways to get an idea of where high and low points are at and also use that with your flashlight. And, if you had access to one or owned one, another great tool is the King-Way Alignment Instrument which uses sensitive machinists levels in two directions to get a sense of bed wear. And you can also attach test indicators to take readings. Great video, thanks for taking the time to make it and share.
Thank you for sharing about that tool. I’d love to find one someday!
@@MaineMachinist - there is one for sale on eBay currently, $5K, I am not the seller.
Send the machine to ' Wonderful process of Fixing things' in Pakistan . . They'll fix it with Welding splatter, good hammerings and Sand . . . And no lubrication at all !
I’ve seen some of those videos!
well done video, very concise and informative......best wishes from Florida, Paul
I appreciate it! Same to you!
Great demo. Thanks!
Thanks for watching!
Hallo from Athens, and thanks for your nice video. I have the Southbend 9a lathe, which is 80 years old and works perfectly, but I think there is some wear in the middle. Since it is difficult to find a new bed, what kind of repair do you suggest ? Should I use the Turcite b tape, or any other special tape or other material? Any other solutions?
Thanks again and best regards. Spiros
Very helpful video thank you
Thank you for watching. I’m glad you found it helpful!
Very helpful, thank you
Glad to hear it! Thank you for watching!
One thing, stone the surface with a precision flat stone to remove burrs ,do this on the machined flats besides the ways as they were machined at the same time as the ways. Use that as a reference when indicating carage and tail stock
Thanks for the explanation very clear and useful info for checking wear ,my old Harrison L5 is worn in around the same area of the bed too,I also did another test by chucking a 16” precision ground bar in the chuck to near zero runout at both ends of the bar.I then clamped a DTI gauge in the tool holder and zeroed at central point of the circle of the bar.Then moved the carriage to and fro along the bar from the headstock towards the tailstock,The results were clearly visible ,in that as the carriage moved along the highs and lows of the ways and bed caused the DTI point to leave the centreline of the circle resulting in some very precise indication of wear.
Thanks for the comment. There are some neat ways to check for wear if you use your imagination! Maybe I’ll try that for the fun of it. Thanks for watching!
@@MaineMachinist Bonus points - 1. You can make a bar with centered conic holes at each end via a steady-rest. Characterize it before use in your shop or in the field. Measure diameter uniformity with a 'mike' or v-block & indicator. Measure the amount and clocking of eccentricities at the ends and along the length between-centers on a lath. Mark the paths of high, neutral, and low run-out. The neutral paths can be used with an indicator to measure horizontal and vertical deviations for both tail stock offsets and tool shifts due to bed wear. No massive surface plates required, just record and subtract the test-bar's variations😊. 2. By measuring and subtracting the front flat's thickness variations, you can use the "Method of reversal" on indicator readings of the flat's top and bottom surfaces to get both the flat's straightness and the indicator's path deviations.
but did it affect your cut much?
you should really make a video for noobs like me!@@fredj.scipione7167
Good ideas...I made a very simple V block to mic the wear on my V ways from top to the underside...my hendey has I think .035 as best I recall...
That’s a neat idea. I love the old Hendey machines. They were built very rugged and most I’ve seen had the hand clutch to engage the spindle. I like that!
thank you so much for the instructions , im newbie , i want to buy used lathe just for a hobbies.
Follow a few of these simple checks and you’ll find a nice hobby lathe! And remember - you don’t need a perfect machine to get started!
16:54 isn't the 3.5 thou vs 5 thou just the v block being at 45 degrees? assuming it's also 3.5 on the other side of the v, 3.5 * sqrt(2) is 4.94 thou.
you'd probably also get that if you positioned the indicator moving vertical instead of measuring tangent to the way
Similarly 5 * sqrt(2) is 7.07 (I guess duh 3.5 is half of 7). why there's 0.002" between measuring tailstock to carriage ways and carriage to tailstock, I have no idea
2:01 - The Visual Inspection Method
3:54 - The Carriage Lock Method
7:10 - The Test Indicator Method
17:36 - Square & Flashlight Method
20:25 - Feeler Gauge Method
Thanks for your terrific description of wear detection. My question, as a hobbiest, how much wear would you accept before saying "I won't buy that one?"
Anything worse than the lathe shown here I would say disqualifies it
Otherwise you’ll face a lot of frustration
how much bed ware is acceptable and what is the potential effect of having the difference shown on this lathe? i intend to use it at home. if i were to go over the surface on a 10 inch part on this lathe, would it be straight within 5 thou since that was about the ware on the ways?
This lathe is used successfully in a professional setting in the repair work industry.
Competent machinists can adjust for bed wear in order to make good parts.
A home hobby user may struggle to hold closer tolerances with this machine, but most Hobby Machinists aren’t doing anything critical anyways
This lathe would turn a taper over 10” of trace for sure. There are means of adjusting for this to compensate, but that’s out of the scope of this comment section.
When you are using the tailstock to indicate the carriage ways some of the indicator reading is due to the worn tailstock ways.
Right. This is a semi crude method of doing it, because as you point out it’s also reading wear from the tailstock ways etc. I can’t think of a perfect way to find out an exact reading on wear, but at least we can get a ballpark idea from these methods.
Thanks for watching and I always appreciate your well informed comments!
When using the dti mounted on the carriage, perhaps indicating the top flat of the front v way may reference a truly unworn surface. Not sure, still lots to learn in this area.
However that still incorporates the saddle wear, rather than isolating it from the bed, giving an idea of total system wear.
One other thought, zeroing the indicator in an area where both ways are minimally worn and advancing into the worn area may lead to more intuitive results, rather than needing to reverse the values afterward. Just thinking out loud.
Good thoughts. There is no perfect way to read wear, like I mentioned in the video, without having the entire bed on a known reference surface.
So taking as many measurements as possible to estimate the bed wear is important. I see no reason why your ideas wouldn’t be helpful to gain even more information and continue to add to the big picture.
Thanks for commenting and if you think of other ways, please leave them in the comments
Would like to see a video of how you compensate for us hobbiest
Back when I was in trade school, the lathe instructor was an old retired Tool Maker. He told us about an work out turret lathe he used to operate when he first started out as a machinist.
The machine was worn, and through experience they knew that the tool height dropped over a certain portion of the ways, which increased the diameter of the work because the tool was no longer contacting on the center line, but below it.
Eventually he marked the worn section of the ways and found that it he leaned his knee on the carriage as it moved along that section of the ways, it would compensate for the tool drop enough to make it turn true.
There are so many funny stories like that. It takes time and experimentation with your machine to get to know it’s quirks.
For example, on this Logan I know the tool drops near the chuck, as shown. If I don’t want to leave material for sanding as an option, I’ve sometimes extended the work out and supported it with a steady rest so I’m turning beyond the worn area.
There are little strategies you can develop over time
I’d be careful with the precision level. I know that starrett levels have a relief ground in the middle to compensate for thermal expansion.
Yes, mine does have that
Another possibility is to Clamp 2 Machined Blocks one at the Headstock the other at the Tailstock then stretch Piano Wire across them. Measurements between the wire and the Ways will show a Bowing or Wearing. Lots of reprints of Old Machine Shop books, even though times have changed the Principal's remain the same.
That’s a neat thought
you can also electrically isolate the piano wire and apply a voltage to the wire. Using a small speaker or light and an inside bore micrometer the wire distance can be measured when the circuit is completed
You can use an autocollimator to measure wear without needing a surface plate.
I doubt the average viewer is going to purchase a tool that is sold used at prices higher than most hobby lathes they would be evaluating. Also, I’m not convinced it is the best tool for these purposes.
@@MaineMachinist You can also do it with precision levels and a sled, which is a fraction of the cost of an autocollimator. It's just plain wrong to say it can only be done with a large surface plate.
@@stevencolbert2304 Feel free to create a video showing your method and upload it.
9:53 A better way to do that would have been to reference off the unworn undercut in the bed in-between the ways.
If you look at it closely, that surface is pretty rough
@@MaineMachinist From the video it looks like it's in better condition than the ways you were referencing. The problem with the way you were doing it is the wear in the tailstock ways is unaccounted for. So now you know the difference between the tailstock ways and the carriage ways. You don't really know how much wear is actually in the carriage ways.
@@24681359David as mentioned in the beginning of the video, each of these methods is an estimate only.
There is no way to accurately measure the wear in a precision manner without having the bed on a master reference surface like a large granite plate.
All we can do here is *estimate*
@@24681359David that undercut you mention isn’t a precision surface
@@MaineMachinist It's machined into the bed, no? It's also about the only surface on the lathe that's unworn. It should be allot more precise than the worm surfaces you were referencing.
You measuring the wrong way, you are calling the worn area your datum which is an unknown? You should start at the least worn area to set zero then start measuring which will give you the amount of wear?
Also you could have put your indicator on to the clamp face under the Vee and move the carriage the full traverse which will give you the exact amount of wear?
Better think that through again.
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