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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Sun Jun 10, 2018 12:11 pm 

Joined: Tue Aug 24, 2004 10:34 pm
Posts: 679
Wow! Way over my head but that is impressive use of technology. Thanks for posting this Gary. Makes me feel like a caveman. Regards, John.


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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Sun Jun 10, 2018 12:32 pm 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 5486
Location: southeastern USA
Agreed - how accurate is accurate?

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Corollary: "He who does is doomed to watch those who don't repeat it anyway."


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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Tue Jun 12, 2018 9:14 am 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1425
Location: Strasburg, PA
DRS.GPBensman wrote:
Where the old railroad wire and mics practice may get you within .015 to .025".

We have found these scans to cost $15,000 to $25,000.

I'd say that .005 to .010 accuracy is more in line with what a careful machinist can routinely achieve. A .020 diameter string line is still .020 in diameter at the far end of the locomotive. The lasers that McMaster sells make a dot 1/8” in diameter at a range of 25’. The materials needed to string line measure a frame for tram (not counting micrometers)may cost about $200.

My thinking is that a coordinate measuring machine is magnitudes beyond the level of the initial question about tramming the drivers using a laser. You pays your money and you takes your choice.

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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Tue Jun 12, 2018 4:02 pm 

Joined: Sun Aug 22, 2004 9:34 am
Posts: 375
Let's get our technology correct here.

Use an optical laser to perform tramming is not the state-of-the-art.

Using laser technology to measure distances from fixed points or the creation of a "point" cloud is the state-of-the-art.

3D laser scanning has come into its own with advances in the hardware and software. It is being used in the power generation field for component replacements. I've recently witnessed demonstrations to challenge the accuracy and quality of the products. Coupled with high resolutions photographs, the results are amazing.

Scaling this back, the technology can be applied to creating a 3D model of a locomotive frame with all the key planes identified. With fixed reference points, the scanning device can be located in numerous locations around the locomotive and the software is able to assemble the data into a single model. Cylinder centerlines can be located and referenced to any location needed, verticality of shoe faces and angularity of wedge faces can be found, spring rigging points known, etc. Add in your actual driving box dimensions and you soon have your shoe and wedge dimensions.

I think this is exciting technology and we're currently employing it with USSC 148.

G. Mark

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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Wed Jun 13, 2018 8:11 am 

Joined: Tue Sep 14, 2004 7:52 am
Posts: 1425
Location: Strasburg, PA
G. Mark & Gary,

Do your organizations own the 3D laser scanning equipment used, or do you hire a service each time it is used?

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Strasburg Rail Road Mechanical Department


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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Wed Jun 13, 2018 9:11 pm 

Joined: Tue Sep 13, 2005 9:54 pm
Posts: 63
I have used wires for alignment work and years ago learnd a good trick from Matt Gray Baldwin's last employee. When taking measurements to the wire using a ID Mike connected to a battery power buzzer. One electric wire is connected to the wire the other to the mike the end of the mike which contacts the fix point is insulated [I just use a piece of tape adding its thickness to measurement] When mike touches wire you get a buzz and wire is not displaced. Repeatable accuracy about .002 . Baldwin used it for crankshaft bearing alignment checks .
I have also used optical alignment equipment instead of wires very accurate that was the method before lasers used in industry there are optical alignment scopes, transits and optical levels all available on eBay at good prices they will read in .001 easily at 25'
Dennis Daugherty


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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Thu Jun 14, 2018 7:55 am 

Joined: Thu Feb 23, 2017 10:54 am
Posts: 20
Location: Rossville, GA.
Kelly,
We do not own any of the equipment. We have contracted laser scanning companies to come in and do the initial work. Then our CAD guy has all the info in his program to develop all the needed Drawings.
Also, many machine and millwright shops own the digital laser tracker. We hire them to come out at about $1,000 per day to read cylinder and valve bores and all relevant frame locations. For most work on smaller engines, this gets you enough data to do a fine job of running gear alignments. Several hundred points taken in 2 days for $2,000.


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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Fri Jun 15, 2018 8:03 pm 

Joined: Tue Aug 24, 2004 10:34 pm
Posts: 679
At about 3:50 or so into this video on the work Atlas does is some of the equipment talked about. I think. Amazing technology.

https://www.youtube.com/watch?v=W519_INEviA

So is this process usable when say making a new boiler and trying to keep basic dimensions so the new boiler fits the same as the one that was removed? And appliances fit like when they were removed? I know that the close tolerances in tramming is not in the same ball park with dimensions needed in boiler work. But wondering if the scanning would also be used in the process of new boiler mfg especially when trying to duplicate original shapes. Mainly incorporating into a CAD drawing? Between the CAD software and the measuring of the scan seems like true rocket science. No doubt some of my terminology is not correct.

Regards, John.


Last edited by John Risley on Fri Jun 15, 2018 11:54 pm, edited 1 time in total.

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 Post subject: Re: Tramming Drivers with a laser
PostPosted: Fri Jun 15, 2018 8:11 pm 

Joined: Sun May 20, 2007 10:27 am
Posts: 175
Location: New Haven Ct area
I am not too familiar with how driver tramming works but I do have some experience with laser alignment work. We recently switched over to laser shaft alignment at work and it is good to 0.0001" tolerances on high speed shaft alignment but you won't find such systems for $100 at home Depot.

These guys make some of the nicest laser alignment equipment and there are some competitors but I bet you are looking at around $30K+ range to get started. https://www.pruftechnik.com/us/solution ... nment.html

This may be another option for the serious project in addition to scanning


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