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DRAFT REQUIREMENTS

All walls on castings that are perpendicular to the parting plane require draft or taper. This draft is not constant. It will vary with the length of draw (L). The sketches below apply to all surfaces except cored holes and pockets.

A drawing may not show draft. Standard foundry practice is to add draft to the part. To avoid misunderstanding this is synonymous with saying it will add metal to the casting, thereby increasing its size and weight.

Draft will normally be added at the parting line to features perpendicular to the parting line.

Draft may be removed, but must be specified on the drawing. In holes, draft will be added at the depth of the hole decreasing its size. When a designer desires a hole dimension to become larger for reasons such as clearance, he should so indicate.

The direction in which draft is applied is governed by the location of the parting line and will be at the foundry's option unless otherwise specified.

When a parting line interrupts a surface to which draft is applied, the amount of draft to be added will be determined by the longer portion of surface to be drawn. Drafts will be applied to the remainder of the surface to provide a match at the parting line.

Length of Draw (inches) Inches of Draft Degrees of Draft
0.1 0.030 15
0.2 0.030 10
0.3 0.030 7
0.4 0.030 5
0.5 0.030 3
1 0.030 2
2 0.042 1
3 0.052 1
4 0.060 1
5 0.068 1
10 0.096 1


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St. Paul Foundry
954 Minnehaha Avenue West
Saint Paul, Minnesota 55104
(651) 488-5567  Fax: (651) 488-0908
Sales: (651) 312-4734 email

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