Abstract: A combined sewing machine housing and a clamping jig therefor to position the housing for machining purposes comprises a housing bed arm having a column connected to one end and extending upwardly therefrom and supporting one end of an upper arm. The clamping jig includes a post having stop guards thereon for aligning the upper arm and bed arms and column so that they may be positioned on the top of the jig. The sewing machine housing also has a plurality of bearing surfaces defined thereon which may be aligned with or engaged over a corresponding number of clamping elements in the form of rotatable dogs. When the housing is in position on the clamping jig it will be aligned so that one clamping dog enters through an opening of the sewing machine housing and may be rotated into a position to clamp against a bearing surface and the other clamping dogs may be rotated to engage over a bearing surface which is positioned alongside of it.