inverted v templates

expressline99

Registered
Registered
Joined
Nov 29, 2015
Messages
439
I'm reading the Connelly book and currently reading about templates frequently used and made. Are v templates (male and female) available? I assume made similar to v blocks but with different angles? If so what are they called in current terms? I can't seem to locate any using "v templates" Since this are used to ensure there isn't tilt occurring from uneven wear and there are 2 on my Logan bed... I thought I would look into it. Ideas suggestions?


Paul
 
The vee templates Connelly talks about are all ways special made to each machine tool manufactures needs. Most machine tool manufactures in the days made their own. They poured the castings in their own foundry, seasoned the castings, machined them, stress relieved them, finish machined them, last scraped them straight.
I have a couple of dovetail templates made by a long gone lathe manufacture I got ahold of many years ago. vee templates and or straight edges were not common. You pretty much have to make your own. These templates were only made about 12" to 24" long. They were not made the length of a lathe bed. They were only made to control the form of the vee so they would be consistent from machine to machine.
 
Hi Paul. The V ways of machines need to fit each other when new, and are machined to fit, and sometimes scraped to match. Specific angles are called for, a manufacturing neceessity. In reconditioning a machine, specific angles matter not at all, the mating parts just need to fit each other. If the dovetail is nominally 55 degrees, and we scrape both surfaces in at 55.437 degrees to match, nothing is lost, so long as the geometry of the total machine is correct and the mating surfaces match each other with full bearing.
 
Thanks, Ken

Hi Paul. The V ways of machines need to fit each other when new, and are machined to fit, and sometimes scraped to match. Specific angles are called for, a manufacturing necessity. In reconditioning a machine, specific angles matter not at all, the mating parts just need to fit each other. If the dovetail is nominally 55 degrees, and we scrape both surfaces in at 55.437 degrees to match, nothing is lost, so long as the geometry of the total machine is correct and the mating surfaces match each other with full bearing.

Hi Bob, the angles make total sense said that way. ..I keep reading and trying to understand it. It's still difficult for me to visualize how to measure the parallelism, tilt, square...etc etc.
Where to reference from is my main issue on the lathe. I'm starting to get how it would work on a mill. However, working compound down on a lathe still mixes me up. I really need a lesson on Metrology.

Paul
 
Paul,

Trying to establish reference planes to work from are not that difficult to do in your case with your Logan lathe bed. Most all surfaces are machined/planed in the same setup when done. If you are trying to determine how much wear you have the bed ways, you have to work off the unworn surfaces of the bed. These surfaces are usually the sides of the bed, and the surfaces between the vee's and flats. From these surfaces and the use of fixturing that rides on these unworn surfaces, you can measure, with dial indicators, the wear on the vee's and flats normally used for the saddle/carriage and tailstock. The only other way to measure this is to put the bed up on a planer or surface grinder or large CNC mill and measure. Now, for making the vee's and flats, flat and straight again. You either re-machine these surfaces on a machine capable of doing so or using a straight edge of known straightness, scrap and make flat again.
One thing to remember, when you re-scrap or machine the ways, the saddle has to be re-fitted to the bed ways. And depending how much material is removed, may have an effect on the lead screw alignment with the carriage, too.
 
Paul,

Trying to establish reference planes to work from are not that difficult to do in your case with your Logan lathe bed. Most all surfaces are machined/planed in the same setup when done. If you are trying to determine how much wear you have the bed ways, you have to work off the unworn surfaces of the bed. These surfaces are usually the sides of the bed, and the surfaces between the vee's and flats. From these surfaces and the use of fixturing that rides on these unworn surfaces, you can measure, with dial indicators, the wear on the vee's and flats normally used for the saddle/carriage and tailstock. The only other way to measure this is to put the bed up on a planer or surface grinder or large CNC mill and measure. Now, for making the vee's and flats, flat and straight again. You either re-machine these surfaces on a machine capable of doing so or using a straight edge of known straightness, scrap and make flat again.
One thing to remember, when you re-scrap or machine the ways, the saddle has to be re-fitted to the bed ways. And depending how much material is removed, may have an effect on the lead screw alignment with the carriage, too.

I went out and took a look at this on the lathe. I can see now there are 2 machined surfaces on each side of the ways that can be used. Those sides jumped right out at me this time. Seemed to me any machined edge would have been a bearing spot. I think that's why it never occurred to me. Simple when looking at it now. Both inner and outer flats have zero contact with any sliding member. But they need some non-abrasive cleaning as there is over spray from painting and various material stuck to them.

Paul
 
Most machinery has reference surfaces built in, and often it is intentional. You are not the first one who needed to measure their lathe for wear, not by a long shot. At least you have some input on how to do it correctly. If you want to make some templates to check out the V-ways, you will need to make them to fit the ways as they originally would have been when new. There is usually negligible wear at the tailstock end of the bed, and also very close to the headstock to use as patterns. On some lathes, extended ways support the headstock in the correct position, and those surfaces should stay pristine, but require removing the headstock to get to them, not exactly a trivial task... The ways near the tailstock end are usually adequate for the purpose. The templates need to fit the factory ways, not your worn ones, and also need to have reference surfaces, typically the flat tops or the bars, that are parallel to the V-ways and also the same distance from the V-ways. I think I remember Connelly covering making templates pretty well in the book, except he made it sound easy, and it no doubt was for him. I really recommend that you read that entire book, cover to cover, and get some serious scraping practice and training, before attempting any portion of a reconditioning to your lathe. There are many nuances that can and will influence the final results as well as the overall difficulty of the project. Make sure you pretty much understand the entire project and the work flow sequence before starting any part of the job. If you start with fitting the wrong parts in the wrong way, you can end up with major metal removal required further down the line, or starting over at the beginning... BYW, I am by no means any kind of expert at this, far from it, but I have read and studied it pretty well, and do have some limited experience with scraping and with adjusting the fits of machine members.
 
Paul,

Here is a fixture I made to check the alignment of my Lodge & Shipley lathe I used to have. If you notice, the rollers, in my case ball bearings, rode on the top of the ways. On this lathe, the top of the ways and the side of the ways is what I located off of. They had no detectable wear.

I also used this fixture to regrind the ways with. And by no means I encourage anyone to use this method to recondition the ways with. I done it just to prove it can be done and I knew what I was doing, too!
 

Attachments

  • L & S Bed End View of Fixture-7.pdf
    21.8 KB · Views: 50
I should have made it clear in my post above that the templates I was describing would not just be for checking the ways for wear, but also for critically checking the ways as work proceeds during reconditioning. The templates would need to be joined together solidly into a single fixture for measuring both ways at once, to make sure the V's are the correct distance apart and vertically parallel as well, while forming the correct shapes and heights. Simpler templates can be used for just checking wear.
 
Most machinery has reference surfaces built in, and often it is intentional. You are not the first one who needed to measure their lathe for wear, not by a long shot. At least you have some input on how to do it correctly. If you want to make some templates to check out the V-ways, you will need to make them to fit the ways as they originally would have been when new. There is usually negligible wear at the tailstock end of the bed, and also very close to the headstock to use as patterns. On some lathes, extended ways support the headstock in the correct position, and those surfaces should stay pristine, but require removing the headstock to get to them, not exactly a trivial task... The ways near the tailstock end are usually adequate for the purpose. The templates need to fit the factory ways, not your worn ones, and also need to have reference surfaces, typically the flat tops or the bars, that are parallel to the V-ways and also the same distance from the V-ways. I think I remember Connelly covering making templates pretty well in the book, except he made it sound easy, and it no doubt was for him. I really recommend that you read that entire book, cover to cover, and get some serious scraping practice and training, before attempting any portion of a reconditioning to your lathe. There are many nuances that can and will influence the final results as well as the overall difficulty of the project. Make sure you pretty much understand the entire project and the work flow sequence before starting any part of the job. If you start with fitting the wrong parts in the wrong way, you can end up with major metal removal required further down the line, or starting over at the beginning... BYW, I am by no means any kind of expert at this, far from it, but I have read and studied it pretty well, and do have some limited experience with scraping and with adjusting the fits of machine members.

I don't anticipating starting work until I am done reading it and have more practice with you and the guys first. My mind spins in a lot of directions. So all my questions are advance research. As well, I won't practice on my lathe. I think I will buy extra parts for it to practice on. Maybe an extra compound and extra cross slide that would fit?
 
Back
Top