Autocollimator's and alignment Telescopescopes

**Ueee** · 28th October 2012, 01:20 AM

I've been thinking, maybe a little too much, about my LeBlonds bed. I know it is worn, i also know by the overall feel of the saddle and slides that i want to get her right and keep her for well in to the future.
My first thoughts were to get the ways ground in Sydney, although i have not had a quote going by other stories i know that it will not be cheap. After i asked about how a large planner's ways would be made flat Greg Q piped up with "an autocollimator, wires and sag posts, or she'll be right.."
Of course i immediately went off and started researching autocollimators, which lead to alignment scopes, of which there appears to be 2 types, microscopes like Phil "Machtool" and Stuart have, and telescopes....but just to confuse things there are also autocollimating alignment scopes....
I have found you can purchase reticles for most microscopes of the shelf to .002" graduations, but then i have to deal with wire sag, right?

I know what you are thinking....scraping in any lathe bed, not to mention one as big as blondies, will be a huge job...i know...
BUT
If i get the bed ground i will learn nothing and will part with a large sum of cash and walk away with no tangible items....OR i could spend the money on a really good level, a big surface plate and camel back and go down that path....OR buy a used scope like say this eBay Australia: Buy new & used fashion, electronics & home d and a smaller surface plate etc and do it that way. The advantage of either doing it myself way is i will have the tools for life and be able to use them on my other machines, both the ones i own now and in the future.

I have done a fair amount of googling on using scopes to measure a plane for flatness, and am a bit stumped on the autocollimator and how it will work. From everything i have read it measures angle and not height difference, so what happens when you compare 2 parts of the ways that are parallel but not on the same plane?

Can anyone shed more light on the best tool for the job, and any other links, books etc that would be worth looking at? (a copy of Connelly's is on the way)

Googling autocollimators is a bit of a pain, you have to wade through the telescope alignment stuff and all the astronomy buffs to find the good stuff.....

Some links:http://services.eng.uts.edu.au/desma...collimator.pdf

Inmagic DB/Text WebPublisher PRO: 120 records There are a stack of papers here, you have to register to download but they look pretty interesting.

Of course if i were in Melbourne i would already be grooming Ray with fermented beverages.....

**.RC.** · 28th October 2012, 06:58 AM

You can use a level to measure wear...

**Bryan** · 28th October 2012, 08:09 AM

Ewan, your first task is a survey to quantify the wear. Then scrape some smaller stuff so you know what's involved. Oh yeah, read the wreck and new toy stickies in the Monarch forum on PM too.

**Greg Q** · 28th October 2012, 06:32 PM

When I took my first scraping class in Seattle one of the instructors had a complete, boxed Nikon autocollimator for machine alligment for $500. At the time I was too stupid and/or broke to buy it.

I cannot find the little smiley for kicking myself in the pants.

Greg

**Ueee** · 28th October 2012, 07:07 PM

Originally Posted by Bryan

Ewan, your first task is a survey to quantify the wear. Then scrape some smaller stuff so you know what's involved. Oh yeah, read the wreck and new toy stickies in the Monarch forum on PM too.

Of course a survey is first, but right now i am more thinking of how to ensure i can scrape the bed flat.....
The stuff by Harry on PM is very good, this is just what i was trying to find, someone who has actually gone down this path. He used a level and straight edge/v blocks/kingway tool only, but the EE's bed was only 59" long, i'm looking at just over 8' for the head and tailstock ways and 6'10" for the saddle ways. I just wonder if a level and straight edge would be enough over the longer length.
Having searched for more scopes there are plenty in the USA with mics, most are 1 thou or .02mm. the thing that really draws me to a scope is it works in 2 planes, not just 1 like a level.

At this stage i am probably at least 6 months from actually doing anything, but if i can work out what i need to get can save some $$ and keep an eye out.

I bet you are kicking yourself Greg, that would have been a very handy purchase, but i still can't get my head around the way autocollimators work......scopes are easy to work out.

**.RC.** · 28th October 2012, 07:47 PM

You do not really want a big long straight edge for surveying with a level...

Some thing the Starrett 199 is pretty good @ 15 inches long... (or are they 12?)

you place the level along the bed, marking each deviation from level on paper, then extrapolate that data to a graph which will show the condition of the bed...

This method is written up in Michael Morgans book on scraping...

**Greg Q** · 28th October 2012, 07:49 PM

I cannot shed any light on the workings of an autocollimator. As you say, scopes are intuitive. Here's another idea. A simple laser pointer generates a beam that is dead straight. You could shine any old laser down the ways, just skimming an area that is known good (like under the headstock.) next, examine the bed for areas where the laser is no longer visible skimming the surface. Here you could try shims to see how far below the laser the bed is. This would give you a pretty accurate assessment.

It helps to know that the saddle ways are going to be worn near the chuck, the tailstock ways less so. Similarly at the other end of the bed. MTR will have some clues, as will Harry's articles on discerning wear.
Harry did two earlier articles published in Home Shop Machinist years ago. They were called "Reconditioning a lathe" and "Reconditioning a lathe, revisited"

The laser idea is from something that was posted on HSM...I shall try to find it.

Greg

**Ueee** · 28th October 2012, 07:52 PM

Originally Posted by .RC.

You do not really want a big long straight edge for surveying with a level...

Some thing the Starrett 199 is pretty good @ 15 inches long... (or are they 12?)

you place the level along the bed, marking each deviation from level on paper, then extrapolate that data to a graph which will show the condition of the bed...

This method is written up in Michael Morgans book on scraping...

Thanks for the info RC, as for the straight edge i was more thinking of the scraping, not the survey.....

Plan plan plan......and plan some more

Thread: Autocollimator's and alignment Telescopescopes

Thread Tools

Search Thread

Autocollimator's and alignment Telescopes

Similar Threads

Saw alignment MK3

saw alignment

Very odd mis-alignment problem...

Saw Alignment

Out of alignment

Tags for this Thread

Posting Permissions