Adjustable chair

1. An adjustable leg for a chair, comprising:

a leg housing secured to a seat and including a threaded inner wall;

a leg extension received into the leg housing and including external threaded portions that mate with the threaded inner wall; and

a tab in the leg housing cooperating with the external threaded portions and securing the leg extension at a predefined position in the leg housing.

2. The adjustable leg for a chair as set forth in claim 1 , wherein the tab includes:

a flexing portion.

3. The adjustable leg as set forth in claim 1 , wherein:

a valley is defined on the leg extension between the threaded portions;

the tab is biased toward the leg extension; and

the tab is secured in the valley when the leg extension is at the predefined position in the leg housing.

4. The adjustable leg as set forth in claim 3 , wherein:

the leg extension is unsecured from the predefined position when a force is applied for turning the leg extension relative to the leg housing and moving the tab out of the valley and over one of the threaded portions.

5. The adjustable leg as set forth in claim 3 , wherein:

the tab is positioned to ride on one of the threaded portions when the leg extension is not secured at the predefined position.

6. An adjustable leg for a chair, comprising:

a leg housing secured to a seat;

an insert secured in the leg housing including a threaded inner wall;

a leg extension received into the insert and including external threaded portions that mate with the threaded inner wall, a depression being defined between the threaded portions; and

a tab on the insert cooperating with the threaded portions and the depression, the leg extension being secured at a predefined position in the insert when the tab is in the depression.

7. The adjustable leg as set forth in claim 6 , wherein the insert includes:

a first insert portion including a first portion of the threaded wall; and

a second insert portion including a second portion of the threaded wall, the first and second portions of the threaded wall forming the threaded inner wall of the insert when the first and second insert portions are secured together.

8. The adjustable leg as set forth in claim 6 , further including:

an index, between the external threaded portions, on the leg extension.

9. The adjustable leg as set forth in claim 8 , wherein:

the tab is secured by the index when the leg extension is at the predefined position in the insert.

10. The adjustable leg as set forth in claim 9 , wherein:

a first portion of a wall defining a well of the tab is between the index and a first of the external threaded portions of the leg extension when the leg extension is at the predefined position in the insert;

a second portion of the wall defining the well is between the index and a second of the external threaded portions of the leg extension when the leg extension is at the predefined position in the insert; and

at least one of the first and second portions of the wall defining the well is over at least one of the external threaded portions of the leg extension when the leg extension is not at the predefined position in the insert.

11. The adjustable leg as set forth in claim 6 , wherein the tab is on the inner wall of the insert and includes:

a flexing portion for biasing the tab toward the leg extension.

12. The adjustable leg as set forth in claim 6 , wherein:

the tab is over one of the threaded portions when the leg extension is not secured at the predefined position in the insert.

13. A chair having an adjustable leg, the leg comprising:

an upper leg portion secured to a seat;

an insert secured in the upper leg portion and including a threaded inner wall;

a lower leg portion received in the insert and including a partial external threaded portion, which mates with the threaded inner wall, and a valley; and

means for providing visual and tactile feedback to a user when the lower leg portion is at a predetermined position in the upper leg portion.

14. The chair as set forth in claim 13 , wherein the means for providing feedback includes:

an indicator on the lower leg portion; and

a locking device on the upper leg portion cooperating with the threaded portion and the valley for securing the lower leg portion at the predefined position in the upper leg portion.

15. The chair as set forth in claim 14 , wherein the locking device is seated in the valley and abuts the threaded portion when the lower leg portion is at the predefined position in the upper leg portion.

16. The chair as set forth in claim 13 , wherein the insert includes:

a first insert portion defining a first portion of the threaded wall; and

a second insert portion defining a second portion of the threaded wall, the first and second portions of the threaded wall mating to form the threaded inner wall of the insert.

17. An adjustable leg for a chair, comprising:

a leg housing secured to a seat;

a leg extension received into the housing and including external threaded portions that mate with a threaded inner wall of the leg housing;

a plurality of indices between the threaded portions on the leg extension; and

a locking mechanism associated with the leg housing, preset positions of the leg extension within the housing being determined as a function of respective ones of the indices being engaged with the locking mechanism.

18. The adjustable leg for a chair as set forth in claim 17 , wherein the locking mechanism includes:

a flexing portion; and

a recessed portion biased toward a center of the housing by the flexing portion, the index engaged with the locking mechanism being removably secured in the recessed portion.

19. The adjustable leg for a chair as set forth in claim 18 , wherein:

the indices and the external threaded portions of the leg extension are raised; and

a wall defining the recessed portion rides on at least one of the indices and the external threaded portions when the leg extension is not at one of the preset positions.

20. The adjustable leg for a chair as set forth in claim 18 , wherein the index is disengaged from the recessed portion by turning the leg extension with respect to the leg housing.

21. A method for adjusting a leg of a chair, comprising:

rotating a leg extension within an insert that is secured within a leg housing, external threaded portions of the leg extension mating with a threaded inner wall of the insert as the leg extension is rotated; and

when the leg extension is at a predefined position in the insert, engaging a tab on an inner surface of the insert in a valley between the threaded portions.

22. The method for adjusting a leg of a chair as set forth in claim 21 , wherein the engaging includes:

removably securing the tab in the valley.

23. The method for adjusting a leg of a chair as set forth in claim 22 , further including:

removing the index from the valley by rotating the leg extension.

24. The method for adjusting a leg of a chair as set forth in claim 21 , wherein the rotating includes:

riding the tab over the threaded portions of the leg extension.

25. The method for adjusting a leg of a chair as set forth in claim 21 , further including:

determining the predefined position as a function of an index extending from the insert.

26. The method for adjusting a leg of a chair as set forth in claim 25 , wherein the chair includes a plurality of the legs and each of the legs includes a plurality of the indices, further including leveling the chair, including:

for each of the legs, engaging a respective one of the tabs in a respective valley so that a corresponding one of the indices is exposed.