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Trimble Trimax vs Leica Tripods?
350RocketMike replied 3 years, 4 months ago 27 Members · 46 Replies
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John Putnam, post: 418199, member: 1188 wrote: Yes, that is about it for most work. On the trolley jobs it is not so simple since on some projects we are looking for 2mm accuracies as it moves along the track.
If you don’t mind me asking. How do you achieve those accuracies?
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Fu3l3r, post: 418200, member: 11864 wrote: How do you achieve those accuracies?
Very carefully. Many instruments are capable of it if properly adjusted. It’s the rest of the system you have to pay a lot of attention to. Just exactly how you achieve such accuracies is lot to put in to a posting, but generally you must be doing a lot of little things such as:
- Collimating the instrument daily.
- Adjusting tribrachs and rods daily.
- Short target rods with fresh points, or direct sighting
- Barometric and temperature corrections more than daily
- Backsights to tripod/tribrach targets.
- Check backsights after maybe every shot.
- Stake out to a marker that can be marked to a hair.
- Worry a lot about little things like the coefficient of thermal expansion of your tripod legs.
- Do it from control that has been redundantly tied and adjusted using such equipment and methods.
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Fu3l3r, post: 418200, member: 11864 wrote: If you don’t mind me asking. How do you achieve those accuracies?
As Mark said, very carefully. We do everything he mentioned using 1″ instruments that are well maintained and regularly run through field calibrations. In the case of laying out track with our trolley we resect into multiple targets that are part of very dense control network. Our instrument is usually set up on the rails or as close as we can get so we are relying mostly on EDM distance as the trolley moves closer to the instrument. The instrument is tracking the target on the trolley utilizing ATR instead of Lock (Leica equipment) and shoots in the more precise single mode. We limit the distances to the foresight to under 100 m.
The instrument is only used for elevation and position of the line rail. The trolley has several onboard sensors that deal with gauge and track cant (super). It is a hair raising job. About 50 guys breathing down your back as you tell them which way to adjust the track as they are slinging mud.
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John Putnam, post: 418219, member: 1188 wrote: As Mark said, very carefully. We do everything he mentioned using 1″ instruments that are well maintained and regularly run through field calibrations. In the case of laying out track with our trolley we resect into multiple targets that are part of very dense control network. Our instrument is usually set up on the rails or as close as we can get so we are relying mostly on EDM distance as the trolley moves closer to the instrument. The instrument is tracking the target on the trolley utilizing ATR instead of Lock (Leica equipment) and shoots in the more precise single mode. We limit the distances to the foresight to under 100 m.
The instrument is only used for elevation and position of the line rail. The trolley has several onboard sensors that deal with gauge and track cant (super). It is a hair raising job. About 50 guys breathing down your back as you tell them which way to adjust the track as they are slinging mud.
We aren’t in the 2mm range, but it is still hair raising because you can’t really lower the track once they’ve come through and lined and surfaced it.
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Hey,
As some others have allready pointed out in earlier replies:
Trimax legs are a lot more vulnerable to sunlight and changes in temperature than Leica GST-120. Ive tested this with both legs.
With Trimax the total station loses level in few minutes. (Electronic bubble moves towards sun as the leg facing the sun heats more than the other 2)
This is not an issue with GST-120I currently have both Leica GST-120 and Crain Trimax on the construction site i work on.
Im using GST-120 everywhere but Trimaxes only on inaccurate tasks and usually indoors.Short conclusion:
Leica-GST120 indoor/outdoor exellent
Crain Trimax, indoor exellent but outdoor with changing sunlight/temperature, poor. -
azweig, post: 418242, member: 7041 wrote: We aren’t in the 2mm range, but it is still hair raising because you can’t really lower the track once they’ve come through and lined and surfaced it.
Adam,
The 2mm accuracy range is for direct fixation track. It takes about 6 passes, including layout and as-built, for to get it totally dialed in. To an extent lower is always better. They can always add shims but it is kind of frowned on. -
Quicky conversion: 2mm = 0.00656′
Just a suggestion; piano wire and/or lasers for tangent alignment. Curves are another story.
Also, do they want it flat or level? :smarty:
Sorry – went OT.
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I will look into the leica legs to see if I get better results.
I was thinking of making some insulation sleeves for my trimax legs -
In my opinion it is all personal preference.
I find that ones you buy from the same manufacturer or get with your instrument don’t seem to last as long with my crews. The wood ones may work good in dryers states, but in Washington my crews seem to hate them because they swell and get stuck. I remember from when I was mostly out in the field that i didn’t like them as well. I just tossed some new ones that were in our storage because no one wanted them.I used to use Tri-Max which worked well for me, and many of our crews like the Dutch Hill tripods. They are coming out with a new one that i just saw an a seminar which looks very close to same lock as Tri-max. For me, I personally would choose between those.
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I have tried various tripods over the years, the Leica continues to be my preference, I have noticed for 30+ years since Dutch Hill 1st brought a composite tripod to market that the composites all drift in the sun AND are too stiff, no vibration dampening in windy conditions. Sometimes newer isn’t better, I think the Leica wooden tripods have remained largely same design the last 40 years or so.
SHG
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Fu3l3r, post: 418345, member: 11864 wrote: I will look into the leica legs to see if I get better results.
I was thinking of making some insulation sleeves for my trimax legsI have done this in a way already. It is a high vis skirt I had made to go over our tripods and covers from the top plate down to just before the clamps. I haven’t done any back to back testing but it’s going to be better than nothing. I’d at least make something to cover the black painted section of the top part of the tri max.
I can’t find the expansion rate of the exact material the tri max is made out of, but the linear expansion rates of most fibre reinforced resins seem to be around an order of magnitude higher than that of wood. So I’d guess keeping sun off the trimax would be a priority. Anything you can make to insulate them would be better than nothing.
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Conrad, post: 418428, member: 6642 wrote: …..
I can’t find the expansion rate of the exact material the tri max is made out of, but the linear expansion rates of most fibre reinforced resins seem to be around an order of magnitude higher than that of wood ….Awhile back I did a comparison of the linear expansion of various materials. The actual difference in a 10′ section of the materials was listed for a 20å¡ change in temperature. Since we typically are well under that length for tripod setups it helps to gauge the potential for drift.
If I find the link I’ll repost it.
Edit:
Here is a bit of what I found:
“The very best material would be Invar by far which has a coefficient of only .0000015” /inch per 1å¡F change. The next best choice is Douglas Fir with a close coefficient of .0000021″ /inch per 1å¡F change. For comparison aluminum has .0000121″ /inch per 1å¡F.Amount a continuous 10′ length of material would expand/contract with a 20å¡F change (assuming homogeneous temperature throughout) by my computation:
Invar = 0.004″
Douglas Fir = 0.005″
Aluminum = 0.030″To compare: 1mm = 0.040″ “
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My favorite are the Sokkia “Professional Series” all North American Maple legs with the knob locks, no levers. Leica GTS120-09 are the 2nd choice, really like the way they lock when collapsed but feet are smaller than the Sokkia’s.
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Mapman, post: 418461, member: 6096 wrote: Awhile back I did a comparison of the linear expansion of various materials. The actual difference in a 10′ section of the materials was listed for a 20å¡ change in temperature. Since we typically are well under that length for tripod setups it helps to gauge the potential for drift.
If I find the link I’ll repost it.
Edit:
Here is a bit of what I found:
“The very best material would be Invar by far which has a coefficient of only .0000015” /inch per 1å¡F change. The next best choice is Douglas Fir with a close coefficient of .0000021″ /inch per 1å¡F change. For comparison aluminum has .0000121″ /inch per 1å¡F.Amount a continuous 10′ length of material would expand/contract with a 20å¡F change (assuming homogeneous temperature throughout) by my computation:
Invar = 0.004″
Douglas Fir = 0.005″
Aluminum = 0.030″To compare: 1mm = 0.040″ “
Yes it worth noting the materials that go into a tripod, and the effects they can have. Wood (along the grain) has a very low expansion rate, and I think Leica has selected their beech wood for its thermal stability and it can be sealed well for moisture (no citation given).
I second fu3l3r’s idea to insulate the legs. I’d do such a thing if the need arose and I’d imagine the speed of horizontal drift and dislevelment would decrease noticeably
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To add to what’s already been stated, interesting read.
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Dutch Hill is coming out with a new tripod this spring, it is really nice. I think they will be setting the new standards for tripods.
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John Putnam, post: 418219, member: 1188 wrote: As Mark said, very carefully. We do everything he mentioned using 1″ instruments that are well maintained and regularly run through field calibrations. In the case of laying out track with our trolley we resect into multiple targets that are part of very dense control network. Our instrument is usually set up on the rails or as close as we can get so we are relying mostly on EDM distance as the trolley moves closer to the instrument. The instrument is tracking the target on the trolley utilizing ATR instead of Lock (Leica equipment) and shoots in the more precise single mode. We limit the distances to the foresight to under 100 m.
The instrument is only used for elevation and position of the line rail. The trolley has several onboard sensors that deal with gauge and track cant (super). It is a hair raising job. About 50 guys breathing down your back as you tell them which way to adjust the track as they are slinging mud.
This is not a rhetorical or sarcastic question: Is this level of accuracy really necessary? I understand that precise prefabrication has pushed the limits of layout accuracy for structures, but is a railyard layed out to 2mm with 21st century equipment really better than a railyard layed out to 5 huns with 1945 equipment? What drives these incredible accuracy specs and what’s the benefit to the railroad?
Doesn’t a little thermal expansion + several thousand tons of traffic blow the rail out of spec on day one anyway?
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Bumping an old thread:
I was thinking of picking up a couple Trimax tripods and I was wondering if anyone knew the dimensions of the legs when closed? Specifically, I am curious to know how big of a slot I need for the box in my truck in order to fit them. From what I’ve seen the foot pegs are kind of large so I want to make sure I account for this.
Anyway, I’m having a hard time finding this info on the web. I found something that suggested the folded dimensions are about 9 inches but I’m not sure if that is the dimension between the fiberglass or the pegs.
Any help would be appreciated.
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@bstrand I suggest 9″ x 9″ minimum. Mine are a four years old, don’t know if new ones have bigger feet. You could maybe go a hair smaller but might have to twist to make them fit
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@bstrand I suggest 9″ x 9″ minimum. Mine are a four years old, don’t know if new ones have bigger feet. You could maybe go a hair smaller but might have to twist to make them fit
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