Reading deg min and seconds

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earlgo
Posts: 1565
Joined: Sat Jan 29, 2011 11:38 am
Location: NE Ohio

Re: Reading deg min and seconds

Post by earlgo » Sat Aug 08, 2020 4:12 pm

Remember this rotab from Small Tools in Euclid OH? I don't know the accuracy but I was impressed with the size.
Small tools rotab.jpg
Rotab
:roll:
--earlgo
Before you do anything, you must do something else first. - Washington's principle.

whateg0
Posts: 944
Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: Reading deg min and seconds

Post by whateg0 » Sat Aug 08, 2020 9:12 pm

Rwilliams wrote:
Sat Aug 08, 2020 1:06 pm
...

Could not find any instruction manuals in the files for the rotary table and will have to use trial and error to sort out its operation. Is equipped with two different crank handles, one for the tilt and one for the rotation of the table. several different holes for the location of the rotation of the table crank location which we have yet to sort out.

Anyone out there have any experience with one of these monsters?
Not sure what feature on a rotary table could be so complicated as to need a manual to explain it unless there are no graduations or something. Even that would be pretty easy to figure out though. What is it you are trying to learn about it?

Dave

whateg0
Posts: 944
Joined: Sat Mar 28, 2009 3:54 pm
Location: Wichita, KS

Re: Reading deg min and seconds

Post by whateg0 » Sat Aug 08, 2020 9:14 pm

I think the op has moved on from this insanity.

But it should be mentioned that precision does not equal accuracy. No matter how many divisions there are, for example, if the table has half an inch of slop in the bearings, it's gonna produce crap results.

Dave

Rwilliams
Posts: 975
Joined: Thu Dec 22, 2005 2:45 pm
Location: Central California

Re: Reading deg min and seconds

Post by Rwilliams » Sun Aug 09, 2020 1:24 pm

WhategO,

The rotary table in question would probably be easy to sort out if the missing handle on the right side of the right handwheel were where it belongs. The fact that the handle is long gone and the entire crank/shaft assembly to make the table rotate will not move at all. Makes us believe the handle could be broken off deep inside in a shaft locking position.

I did not have time for a careful evaluation and put two guys on the task of cleaning it up and trying to make all the parts move. It was their observation that something seemed to be missing due to the empty hole.

Further research reveals it was a surplus item from a sister shop. They sent no information when it arrived over 20 years ago and no one asked questions. It has never been used that we are aware of in our current location. There is a history of the sister shop gifting us items that they are unable to use, figure out, or have found to be in a condition of disrepair and they do not have the time or talent to resolve the issue. Essentially their problem becomes our problem.

In the attached photo, the left handle controls the table tilt. The right handle must control the table rotation. The handle next to the graduated collar of the right crank handle is missing in action and apparently has not been there for two decades or longer.

Further evaluation of the empty hole with some serious lighting will be in order this next week. In the interim, knowing what the missing handle is meant to do is still in question. Any experience with these tables will be appreciated.
Attachments
Pratt Whitney rotary table from eBay, perhaps complete with no missing parts.jpg

shootnride
Posts: 244
Joined: Tue Jun 05, 2012 12:31 am
Location: Sacramento, Ca.

Re: Reading deg min and seconds

Post by shootnride » Sun Aug 09, 2020 4:22 pm

There is a little bit of information on page 16 of this manual.

http://manuals.chudov.com/Pratt-And-Whi ... ioning.pdf

Also, you can purchase a re-print of the manual here:

https://www.ebay.com/itm/Pratt-Whitney- ... 2088635933

Ted
Some people raise the IQ of the room when they enter.........others when they leave.

Rwilliams
Posts: 975
Joined: Thu Dec 22, 2005 2:45 pm
Location: Central California

Re: Reading deg min and seconds

Post by Rwilliams » Sun Aug 30, 2020 9:53 pm

With some careful evaluation, it was discovered that the rotary table had a sump for oil and a drain plug. We removed the drain plug and it was dry of oil. Not a good sign, no wonder it would not rotate when the table clamps were all loose. Filled the sump with a thin machine oil and let it marinate for two weeks. After two weeks of soaking, the crank would still not move the table. Force was then applied with a big piece of wood and a big hammer while turning the crank. Suddenly things let go inside and noises began to let us know that it wanted to be freed up. Took almost half an hour of intense persuasion to make the table rotate completely in both directions and stop making noises of resistance. Found out the hole in the middle of the table is a large Morse taper.

Next up is to continue cleaning the rust of the past decades until it is suitable for service.

armscor 1
Posts: 187
Joined: Sun Jun 12, 2016 3:12 am
Location: Philippines

Re: Reading deg min and seconds

Post by armscor 1 » Mon Sep 21, 2020 7:14 am

Watch Tom Lipton's latest YT video, in awe of such precision.

pete
Posts: 1924
Joined: Tue Feb 10, 2009 6:04 am

Re: Reading deg min and seconds

Post by pete » Mon Sep 21, 2020 2:57 pm

I knew about those very high precision optical dividing heads before Tom's video, but that's the first time I've seen even part of there internals. Yep awe inspiring indeed. Today's CNC no matter how accurate is pretty boring in comparison.

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