This video explains how to add a usable scale value to any Autodesk Revit family and add visible grips to control it.
The steps I used as as follows (though looking at the video it did a few in a different order to those written below but which ever way you do it (video or written) it will work. I have referenced the written step in the video too.
1. Create a new family (Family 1) from the ‘Metric Planting.rft’ template
2. Create a second family (Family 2) from the ‘Metric Planting.rft’ template
3. Create a third family from the template of your choice (the final template type for the family you want to create)
4. In Family 1 create objects you require.
5. Nest them into Family 2 by using the ‘Load into Project’ button.
6. Take a measurement of something on the model in family 2 (I used the diameter (1080) I shall refer to this as ‘DIM1’.
7. Give the ‘Height’ parameter in the Family types dialogue he same value as DIM1.
8. Nest them into Family 3 by using the ‘Load into Project’ button.
(The model may load as a different scale (for reasons unknown to me) so we need to correct this like so…)
9. Measure the same thing as last time on the model in family 3 (diameter 4665.6) and write it down (DIM2).
10. Now do the following calculation (DIM1 x DIM1) / DIM2. (I normally come out with 250 as the answer).
11. Add an instance parameter and call it ‘Scale Factor’.
12. Give the new parameter the value calculated just now (250 in my case(DIM3))
13. Go to the Project browser and associate the ‘Height’ parameter from ‘Family 2’ with the ‘Scale Factor’ parameter in Family 3.
This will now make the model the same size as before. If it’s not quite there you will need to increase the amount of decimal places for your unit precision in the modify tab for both Family 2 and Family 3 before doing both measurements, THEN do the calculation in step 10.
14. Add an instance parameter and call it ‘Scale’.
15. Add an instance parameter and call it ‘Grips’.
16. Give the ‘Scale’ parameter a value of 1.0
17. Give the ‘Grips’ parameter a value equal to DIM1
18. Enter the following in ‘Scale Factor’s formula column (substituting ‘DIM3’ for its value): =Scale * DIM3
19. Enter the following in ‘Grips’ formula column (substituting ‘DIM1’ for its value): =Scale * DIM1
20. Create two parallel reference lines (not planes) at the same distance apart as DIM1 and add a set of aligned dimensions (2 equalled and 1 overall dim) and assign the ‘Grips’ parameter to the overall dimension.
21. Select both reference lines and change their ‘Reference’ value in the properties window to ‘Strong Reference’.
22. Load the model into a project and enjoy the grips on the model and scale value in the properties window!