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Scraping a bed ways longer than my surface plate
- Thread starter jcloucek
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- Apr 8, 2021
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I have personally seen B&S straight edges 15 feet long
arched type.
- Joined
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- Joined
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Connelly's book is missing one thing, an instructor to teach you what he is talking about. There are a series of operations you need to know to proceed.
On long bedways I would use an alignment scope and a tilting level to determine what needed to be done.
On long bedways I would use an alignment scope and a tilting level to determine what needed to be done.
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Leveling has problems if you use a standard level, an optical tilting level with an optical micrometer is needed,
then measuring with an alignment scope.
An alignment telescope and an autocollimator are both optical devices that can be used for different purposes:
Alignment telescope
Used to establish an accurate line of sight. The telescope has a very straight line of sight and a reticle, or crosshair, that defines the center of the line of sight. In alignment telescope mode, the field of view is often measured in minutes horizontally.
Autocollimator
Used to measure angular tilts or rotation of an object. The autocollimator projects a crosshair pattern out to the object being monitored. The device under test is placed in the optical path and reflects the light back into the autocollimator, which can then be inspected via the telescope functionality. In autocollimator mode, the horizontal measurement range is often measured in minutes.
then measuring with an alignment scope.
An alignment telescope and an autocollimator are both optical devices that can be used for different purposes:
Alignment telescope
Used to establish an accurate line of sight. The telescope has a very straight line of sight and a reticle, or crosshair, that defines the center of the line of sight. In alignment telescope mode, the field of view is often measured in minutes horizontally.
Autocollimator
Used to measure angular tilts or rotation of an object. The autocollimator projects a crosshair pattern out to the object being monitored. The device under test is placed in the optical path and reflects the light back into the autocollimator, which can then be inspected via the telescope functionality. In autocollimator mode, the horizontal measurement range is often measured in minutes.
- Joined
- Dec 6, 2012
- Messages
- 2,714
Ever try to level a lathe in plane which has a worn bed? If you place the levels on the worn areas you get inaccurate readings and confusing results. While I applaud this guys efforts and improved results the autocollimator is that it potentially falls into holes or worn areas. This is the same problem same problem as using a straight edge which is short.
If you work off the area under the head stock and right end you get near factory results. So, optics or a long straight edge either way the distance needs to be spanned. Or, as Mrben identifies lots of metal gets removed in an effort to find flat.
Daryl
MN
If you work off the area under the head stock and right end you get near factory results. So, optics or a long straight edge either way the distance needs to be spanned. Or, as Mrben identifies lots of metal gets removed in an effort to find flat.
Daryl
MN
- Joined
- Apr 8, 2021
- Messages
- 88
An alignment telescope and an autocollimator are both optical devices that can be used for different purposes:
Alignment telescope
Used to establish an accurate line of sight. The telescope has a very straight line of sight and a reticle, or crosshair, that defines the center of the line of sight. In alignment telescope mode, the field of view is often measured in minutes horizontally.
Autocollimator
Used to measure angular tilts or rotation of an object. The autocollimator projects a crosshair pattern out to the object being monitored. The device under test is placed in the optical path and reflects the light back into the autocollimator, which can then be inspected via the telescope functionality. In autocollimator mode, the horizontal measurement range is often measured in minutes.
With Jig transits or Alignment scopes you can parallel the line of sight to the unworn ends of a lathe bed, then directly measure the wear with a target. Autocollimators require a calculation to get a usable number.
I can read a high area, slide the target back, remove metal, read it again. This work is interesting but practically speaking you learn the basics on the job and then you get the job , if successful you get more, studying optical alignment helps, owning instruments
helps, this hobby oriented platform means that most of you are clueless people with opinions, for example 3M
never sent an autocollimator out on a web line job, paper mills use jig transits and tilting levels because that is what works. I have an autocollimator as a fixture device
so I can line it up and if something moves or twists I know. I started learning this in 1971.
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- Dec 6, 2012
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- 2,714
Ok....
Lets please get back to the OPs question.
Is there any way to efficiently and effectively and affordably scrape in a lathe without optics and longer straight edges?
I don't see it.
But I want to observe that this is a fair and reasonable question.
As an advocate for fun, affordable and safe shop practices I ask if there is an optimal approach to this question.
Daryl
MN
Lets please get back to the OPs question.
Is there any way to efficiently and effectively and affordably scrape in a lathe without optics and longer straight edges?
I don't see it.
But I want to observe that this is a fair and reasonable question.
As an advocate for fun, affordable and safe shop practices I ask if there is an optimal approach to this question.
Daryl
MN
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