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  • Setting up a Jig

    I have a rusty hulk of an old Nissan 240Z that I need to do major panel replacement on. Structural panel replacement. Luckily I also have a rust free 240Z as well to take measurements and patterns from. I need to make a jig off my good car to help with replacing and positioning the structural panels like the inner rockers and frame rails. Car is very rusty in places and jigging it so that I can position the panels correctly is my only choice. Anyone have any tips, or advice on building the jig? I remember seeing somewhere Peter where you made a jig for a rusty Mustang you were working on. Mine is similar to what you were working with (rust).

  • #2
    When I was younger I did a lot of jig work.

    A popular Jig for classic cars is the global jig.... But again they are very expensive.

    if you’re good with heavy duty welding and set squares you could make a home-made Jig.

    I also use a trammel gauge .... don’t think I spelt that right...🤣 for underbody cross checking.

    Bracing the car is a must for inner Sills ... square box Tube welded from B to B post , A to A , and from A to B post on each side is a good start​​​​​​. .....Remember only work on one side at a time.

    Take our Heavy Front Screen out because in my experience that A- post on Most Classic cars drop down and forward.......!!!!!! Making the doors not fit.

    So Support that A - Post and weld inner sills with 4 wheels touching the ground.....👍. Re hanging Door etc.....
    if the door is empty place a bit of weight inside.

    even when you Brace a old Car the panels will still move.( adjustable bars are available).

    so I also use a centre punch so that I can use my trammel gauge and measure different points on the car .... Then write down measurements in my book , and then re check as l put in a panel.

    hope this helps.

    Sometimes l,ve made British Cars better gapped.😉
    Last edited by Moving molecules .; 01-11-20, 05:52 PM.
    https://www.precisionpanelcraft.co.uk/

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    • #3
      Originally posted by Moving molecules . View Post
      When I was younger I did a lot of jig work.

      A popular Jig for classic cars is the global jig.... But again they are very expensive.

      if you’re good with heavy duty welding and set squares you could make a home-made Jig.

      I also use a trammel gauge .... don’t think I spelt that right...🤣 for underbody cross checking.


      I'm not looking at buying a jig. Used a Cellette fixture jig at one job I had and they are hideously expensive. I do have a lot of experience in heavy collision repair so yes I have a tram gauge and experience, but I'm wanting to make something that will aid me in transferring measurements and correct position from one car to another. In addition to making cross measurements. In both vertical and horizontal planes. Being that I'm replacing inner and outer rockers on both sides, cross measurements alone, aren't going to be good enough as I will have nothing original to base off of. Hence my thinking for needing a "jig" of sorts to establish a base. Mainly for the structural parts of the vehicle. Unibody rails and the inner rockers. I know Peter did something similar to what I'm thinking but I can't find the thread (on another site) Essentially what I want it for is positioning the rails and inner rockers correctly in both x and y planes. I will be bracing the body as best I can before cutting anything as well.

      What I'm thinking is, full length of the good correct car, 2 lengths of box tubing, with cross pieces of tubing along the length of the vehicle at various points, and using rod or small tubing attached to the cross pieces to set correct position height etc at various points. Main thing that is tripping me up is setting the reference height. My thinking is get the "jig" level in both planes and get the car level in both planes (car that I'm taking measurement off of) and that will transfer to the other car correctly provided I level the jig and and car when setting it up on the car I'm repairing. Being that I am working off a concrete floor and not a square level frame machine I have to account for the difference in the floor. I think leveling everything before setting up the measurements on the good car and then leveling everything the same way on the repair car will allow the measurements to transfer correctly. Anyone have thoughts as to that?

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      • #4
        I should also add that I will be leaving the suspension and motor installed in the car at least until I get the center section done (inner rockers and adjacent rust). Good car has motor and suspension installed as well.

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        • #5
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          Originally posted by Chris_Hamilton View Post

          I'm not looking at buying a jig. Used a Cellette fixture jig at one job I had and they are hideously expensive. I do have a lot of experience in heavy collision repair so yes I have a tram gauge and experience, but I'm wanting to make something that will aid me in transferring measurements and correct position from one car to another. In addition to making cross measurements. In both vertical and horizontal planes. Being that I'm replacing inner and outer rockers on both sides, cross measurements alone, aren't going to be good enough as I will have nothing original to base off of. Hence my thinking for needing a "jig" of sorts to establish a base. Mainly for the structural parts of the vehicle. Unibody rails and the inner rockers. I know Peter did something similar to what I'm thinking but I can't find the thread (on another site) Essentially what I want it for is positioning the rails and inner rockers correctly in both x and y planes. I will be bracing the body as best I can before cutting anything as well.

          What I'm thinking is, full length of the good correct car, 2 lengths of box tubing, with cross pieces of tubing along the length of the vehicle at various points, and using rod or small tubing attached to the cross pieces to set correct position height etc at various points. Main thing that is tripping me up is setting the reference height. My thinking is get the "jig" level in both planes and get the car level in both planes (car that I'm taking measurement off of) and that will transfer to the other car correctly provided I level the jig and and car when setting it up on the car I'm repairing. Being that I am working off a concrete floor and not a square level frame machine I have to account for the difference in the floor. I think leveling everything before setting up the measurements on the good car and then leveling everything the same way on the repair car will allow the measurements to transfer correctly. Anyone have thoughts as to that?
          Sounds a great plan so you mostly worried about heights?

          if you contact 240 Z club or Thatcham they can supply you with extensive Jig drawings.
          Last edited by Moving molecules .; 01-11-20, 06:07 PM.
          https://www.precisionpanelcraft.co.uk/

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          • #6
            Main concern is getting the correct "datum" height. Working off a typical concrete floor, not horribly uneven but not level (no concrete floors are perfect) So I'm trying to figure how to accurately transfer the "jig" from one car to another. Only way I can think is to level the good car in both planes and then do the same with the car I'm repairing. Fit the repair car to the reference points in undamaged places and go from there. Actual measurements and reference points I'll take off the good car.


            "Jig" might not be technically the correct term for what I'm planning. But the idea is the same. To have something to base off of when installing the inner rockers and unibody rails.
            Last edited by Chris_Hamilton; 01-11-20, 07:13 PM.

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            • #7
              In terms of taking and transferring measurements, what you're describing is what I do with a pointing machine on the majority of my stone projects. The only part I'm not sure about is whether you need to hold the new part in place with this measuring device while you install it? Even if that's needed, a pointing machine would be the way I would proof and correct its placement.

              For a pointing machine, you only need static but corresponding foundation points on the model and the job. The feet of the pointing machine are installed in these points to either capture a point in 3D or create/apply that point in 3D. Foundation points are either embedded in the model material and job material or in a chassis built around either to host these points. Old ways were to build a proper measuring frame around model and job, either box around or radial above and measure & apply the lateral X from the plumb Y. BTDT, Real PIA work Compasses also work great but are more complicated to learn. Pointing machine is best and fastest for 1:1 work. I only have to resolve the foundation points between model and job and then use them consistently.

              Things like crooked floors mean nothing as long as foundation points do not change. We never trust anything except the actual model and job because we always work in a somewhat harsh environment. As long as your foundation points are static and used properly, it would be no big deal to take measurements from a car on four wheels and transfer them to a body that was sideways or upside down on a rotisserie. For larger work, the original foundation points are used to define new foundation points so the same small pointing machine & chassis can be placed into a new work area instead of using a chassis that's 8'-10'-+ long and unmanageable.

              I would attach material to host foundation points. Something that bolts to common points between vehicles and probably trued from known correct chassis dimensions. I like to use threaded screws/bolts where the actual foundation point will be so they are easily adjusted. Take other measurements in undisturbed areas to establish the baseline and equalize the foundation points. When multiple points taken and applied are consistent (ideally they're identical) , youre done. secure the screws/bolts and go to work. Now you'll know the measurement of areas on the model (good car) can be applied to the job (bad car) with confidence. When reproducing an old work that cannot be damaged, we will use an exterior framework of some design to host foundation points.

              Link to wiki is included and more is shown in my Kiwi John carving thread. The Bust of Christ was pointed with a pointing machine. That's one of the reasons I posted about the project and method. For a short job like this (relatively few points vs hundreds or thousands) I'm sure a simple pointing machine could be fabricated for your use. The pointing machine is generally clamped to a chassis/frame used for that specific project. Unless you're doing duplicates/multiples, you always use a different chassis configuration.

              I see people building elaborate and cumbersome multi-needle or pointer modern contrived "measuring frames" to take a large quantities of measurements at once. I have the same opinion about these contraptions as Peter does about FSPs....

              If this might suit your project, I'm glad to do what I can to help.

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              • #8
                Interesting Cliff but seems way too complicated for my little brain. Method I'm describing is how I have seen it successfully done and how I essentially repaired heavy collision on Mercedes and BMW's using a Cellette fixture frame machine. Difference here is I don't have the table. What I'd like opinions on is the leveling aspect of my question. Will that be enough to establish a base datum (reference) line?

                Matt I don't really need drawings or reference data as I have the good car to get all that info. Main concern is having the datum line (base line the measurements are made from) accurate so that when I transfer the entire setup to the repair car any differences in the floor or ride height do not transfer to the car being repaired. Think of the baseline being the top of the two pieces of tubing that will run lengthwise down the middle of the car. Imaginary straight line coming off the top of the tubing lengthwise and crossways. I need that to be the same when the fixture is under both cars in order for things to be accurate. If I measured both with the jig in the exact same place on the floor this would not be a concern but since I can't do that I'm trying to work out in my head the way to compensate for any difference in the floor. Setting the good car and jig fixture to dead level in both planes then doing the same with the fixture and the car I'm repairing seems the best way to compensate for this. Any adjustments or differences in ride height between the two (there will be) could then be easily dealt with if the baseline is known to be good. Agree? Disagree. Appreciate any thoughts, I know this isn't the easiest thing to try and wrap ones head around.

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                • cliffrod
                  cliffrod commented
                  Editing a comment
                  Sounds good. It's far more complicated to explain in text than to execute. In terms used here, we have to determine a datum line/plane on the model and then establish it on the job. This datum plane is defined by three foundation points that are common to both model and job. Those are used over and over again to accurately position a measuring device to take, transfer and evaluate measurements. This eliminates the need for a table, flat floor and additional jig so the work can be done anywhere, from the floor of a studio to an outdoor venue on scaffolding 50'+ in the air. Lots of ways to get to the same result.

              • #9
                Not sure where you are located , but you can find old alignment benches for close to scrap prices ,

                And use Celette for the data if its available , unless the Z car factory repair manual has the same info ,

                I will look and see if I have a Data sheet !

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                • #10
                  Thanks Dave, no need, I do appreciate it though. . FSM has the data. I have the FSM and a mint 72 240Z that has never had any rust to use as well. I have a specific question but I have worked it out pretty well in my head. Thanks everyone.

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                  • #11
                    Click image for larger version  Name:	2D340B6E-EDC6-4EAD-BD6A-978645892B48.jpeg Views:	0 Size:	2.93 MB ID:	4511 Click image for larger version  Name:	0C0A9E0C-A0F7-42E2-A974-C7EC027E0F64.jpeg Views:	0 Size:	2.68 MB ID:	4510 Hi Chris, the vertical Datum line as we know it is set up for each model as dictated in the Jig instructions.

                    The Vertical datum line for this old Morris Minor runs though the centre of the eye bolts on the front and rear suspension....👍 and is 10 11/16” High from the ground.

                    So Obtaining the correct instructions for your car could help show you where the datum line runs....😉

                    If l was doing it a my Shed , l would cross check the underpinnings of your Good car first. Should be quite good measurements from where you normally load a car on a Jig ( middle 2/ 3rds ).
                    this will see if the cars Square but WILL not be able to check the heights of the points measured.

                    And then would put the car on good quality tall axle stands and get the car as level as possible so yes check the floor is flat as you can find .

                    Now run with me here ... the 4 points you used to cross check the underneath of your good car .... you can now measure down to see if your good car is sitting right on the vertical plan .... if one measurement is off the floor is out ...... or your car is out ?.
                    this is why we always start on a car on the strongest suspension points.

                    you can always confirm this by checking more and more points to get the information you need.

                    now you have more information to make a decision .

                    or to modify your measurements to use on your old car.

                    you’re never going to get this mm perfect.

                    trying to describe this is very difficult.

                    did I help ....or am I totally not getting where are you want to go.
                    Last edited by Moving molecules .; 01-11-20, 11:36 PM.
                    https://www.precisionpanelcraft.co.uk/

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                    • #12
                      Thanks Matt, appreciate the help. After thinking about it more and going over the measurements that I have from several years of 240Z FSM's that I have, I have pretty much worked it out in my head what I need to do. Thanks to you and everyone else for the help and ideas. I'm looking forward to starting a build thread here of this car. I'll have some pics of the setup in that thread. Maybe it'll make more sense with pictures.

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                      • #13
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                        https://www.precisionpanelcraft.co.uk/

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                        • #14
                          Spot on....We know you can do it. ..... l know the boys at Fourways here in the U.K. they know there 240Z,s.

                          l make a pair the arch,s for one around 2002 when at a Ford Bodyshop.👍
                          https://www.precisionpanelcraft.co.uk/

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                          • #15
                            I have a similar problem repairing my Sunbeam Alpine convertible; these thought may be of relevance.

                            1. Obtain a chassis drawing
                            2. Find the most level floor possible and check the accuracy of such.
                            3. Possibly using a sheet of MDF or similar, adjust the sheet until it is level. Self-levelling grout may be another option.
                            4. Inflate all tyres to exactly the same amount and place the car on the level area.
                            5. Check the height of the body from the floor, do this at the measurement points shown on the drawing, I suggest suspension points might be a good place.
                            6. Jack the car and support on screw-thread stands until the datum points are all exactly (+/- 1mm) at the same altitude.
                            7. Under the car measure as accurately as possible, two points which are in the centre of the body; one towards the rear one towards the front. Permanently mark these points on the body. Drop a plumb-bob and mark the points on the floor; a line between these two points represents the centre-line of the car. This is immensely useful for checking wheel alignment and body distortion. Some cars leave the factory asymmetrical!
                            8. Using a string line outside the car, measure with a steel rule, or tape, or trammel the distance to the centre line.
                            9. In Chris's case and mine I would make a steel bench, which is stiff and level; set up a datum string line and a datum centre-line on the bench and then start transferring measurements from the car.

                            I plan to make some sort of fasteners or locators, which will be attached to the table and then later the car can be bolted to them. If they are adjustable they can be levelled with a laser-level, even if the table is not perfectly flat. Once it is secured, bracing can start on the body and new panels made. As my car shows evidence of a crash repair, I am particularly keen to see if the body is bent. In Chris's case he can take his measurements from the good car by either levelling the floor, or using Cliffy's pointing method.

                            I too welcome thoughts on the matter,

                            Cheers Charlie.

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