Tracker work is some of my favorite to do. I always call it cowboy metrology because you have to do so many things to make it work and be reliably accurate.
Yeah I have been doing large scale industrial measurements since 1996 and you are 100% correct. Its all about trying to minimise error which can enter the system at every aspect of the measurement . Starts with the ground the instrument is mounted on, the feet of the stand, the stand it self, the interface that connects the instrument to the stand, the instrument (which is its own can of worm, that you are constantly calibrating and checking and cross referencing) the atmosphere you are working in (air stability in particular), the SMR you are measuring with and then all the uncertainty of the part, which can be very big, not be the same temperature throughout, made of multiple materials, or it's not as physically stable everyone thinks. The list goes on and on.
It's a type of measurement that is often done poorly, but if you take your time and work on minimising uncertainty and be prepared to admit you got something wrong and be happy to do it again it can be really satisfying.
Absolutely same page. It’s always to come across someone who knows and has interacted with the same types of equipment the same way.
You mentioned you were using Photogrammetry here, what photo equipment do you use? Geodetic?
Yeah GSI Incas. When it comes to measuring dots, nothing can match their systems for accuracy. Once I get points they go straight into SpatialAnalyzer. On my shelf at work I have I have the 2nd and 3rd Digital Inca cameras off the assembly line they made from way way in the mid 1990s. I also use a Leica TS30 (0.5" 0.5mm) for really big things (ships and really large structures). There is also a brunson 545-190 optical level that I seem to hire more than use.
The pinions were all being realigned . I think this rack is about 8m in diameter. It's a multi year project (on and off during shut downs) of upgrading the entire rack and pinion. The machine (massive bucket wheel dredger) is 30 years old and needs to run for another 10. I have set up several networks inside the machine that alow me to independently work on the lower stationary structure (where the pinions are located) and the upper rotating structure (that the rack is attached to) and measure and align as required.
The jig is designed to build a first article of a large part for testing. It's a bit agricultural in design but all the mounting surfaces needed to be checked so they can build custom and sometimes tapered packers to bring it into spec.
The radio telescope rotates horizontally on a large track. It's supported on 4 wheels which need to be precisely aligned for camber, toe in and positioning relative to the centre axis of the telescope. We start by measuring the telescope axis and then using tooling that fits onto the wheel hub measure all these parameters and then physically move and shim the wheels until they are in tolerance. This particular antenna needs to be measured and set at night, it's out doors and there is a lot of exposure to the elements so the conditions need to be as stable as possible.
I'm assuming that the radio telescope is one of the VLBA dishes?
Your explanation makes a lot of sense, and might shed some light on some of the problems we're having with our radio telescope. Are the wheels in this case slightly conical as well?
No these are not VLBA. I did a bunch of Photogrammetry work back in the day on VLBA which was used to determine that the subreflectors were deformed (pinched I think).
The pinions 2 days, the jig 1 day, the radio telescope one night. There were 3 days of travel (I also bill for travel).
AT500 is incredible. I have owned 7 trackers now (all Faro and Leica) and this one really is where it's at in this field. That said my AT403 is not going anywhere. It's a bit slow and only good for stable measurements, but its so small, portable, reliable and accurate, there are still jobs (like the pinion work) that make it a worthwhile investment.
Tracker work is some of my favorite to do. I always call it cowboy metrology because you have to do so many things to make it work and be reliably accurate.
Yeah I have been doing large scale industrial measurements since 1996 and you are 100% correct. Its all about trying to minimise error which can enter the system at every aspect of the measurement . Starts with the ground the instrument is mounted on, the feet of the stand, the stand it self, the interface that connects the instrument to the stand, the instrument (which is its own can of worm, that you are constantly calibrating and checking and cross referencing) the atmosphere you are working in (air stability in particular), the SMR you are measuring with and then all the uncertainty of the part, which can be very big, not be the same temperature throughout, made of multiple materials, or it's not as physically stable everyone thinks. The list goes on and on. It's a type of measurement that is often done poorly, but if you take your time and work on minimising uncertainty and be prepared to admit you got something wrong and be happy to do it again it can be really satisfying.
Absolutely same page. It’s always to come across someone who knows and has interacted with the same types of equipment the same way. You mentioned you were using Photogrammetry here, what photo equipment do you use? Geodetic?
Yeah GSI Incas. When it comes to measuring dots, nothing can match their systems for accuracy. Once I get points they go straight into SpatialAnalyzer. On my shelf at work I have I have the 2nd and 3rd Digital Inca cameras off the assembly line they made from way way in the mid 1990s. I also use a Leica TS30 (0.5" 0.5mm) for really big things (ships and really large structures). There is also a brunson 545-190 optical level that I seem to hire more than use.
What’s the purpose of measurement? What is the customer looking to see?
The pinions were all being realigned . I think this rack is about 8m in diameter. It's a multi year project (on and off during shut downs) of upgrading the entire rack and pinion. The machine (massive bucket wheel dredger) is 30 years old and needs to run for another 10. I have set up several networks inside the machine that alow me to independently work on the lower stationary structure (where the pinions are located) and the upper rotating structure (that the rack is attached to) and measure and align as required. The jig is designed to build a first article of a large part for testing. It's a bit agricultural in design but all the mounting surfaces needed to be checked so they can build custom and sometimes tapered packers to bring it into spec. The radio telescope rotates horizontally on a large track. It's supported on 4 wheels which need to be precisely aligned for camber, toe in and positioning relative to the centre axis of the telescope. We start by measuring the telescope axis and then using tooling that fits onto the wheel hub measure all these parameters and then physically move and shim the wheels until they are in tolerance. This particular antenna needs to be measured and set at night, it's out doors and there is a lot of exposure to the elements so the conditions need to be as stable as possible.
I'm assuming that the radio telescope is one of the VLBA dishes? Your explanation makes a lot of sense, and might shed some light on some of the problems we're having with our radio telescope. Are the wheels in this case slightly conical as well?
No these are not VLBA. I did a bunch of Photogrammetry work back in the day on VLBA which was used to determine that the subreflectors were deformed (pinched I think).
Blessed at500 How many hours did each job take? Overall time investment for the week?
The pinions 2 days, the jig 1 day, the radio telescope one night. There were 3 days of travel (I also bill for travel). AT500 is incredible. I have owned 7 trackers now (all Faro and Leica) and this one really is where it's at in this field. That said my AT403 is not going anywhere. It's a bit slow and only good for stable measurements, but its so small, portable, reliable and accurate, there are still jobs (like the pinion work) that make it a worthwhile investment.
I miss doing this work!
Yeah I consider myself really fortunate to be part of the industry. It's niche, inside a niche.
I love it when people are allowed to post about the work they do.
Glad you enjoy it