BAD
Tech Info


Shafts and Holes
For what it’s worth…

Shafts and Holes
Guidelines for hole and shaft jobs (no jokes please); hole basis. Different types of fit for bolts, pins, etc.

Force fits. Mechanical pressure is required for assembly and, when assembled, no dismantling is likely to be necessary As the shaft is larger than the hole in this case, interference fit is a general term also applicable.

Driving fits. These are a little less tight than force fits and, one part can be driven into the other. This is also an interference fit.

Push fits. Slight manual effort is required to assemble the parts in this case. A push fit is suitable for detachable or locating parts but not for moving parts. As the clearance is small or negligible, this is termed a transition fit.

Running fits. These are suitable for moving parts such as axles and so on. All running fits are clearance fits.




Nominal Diam.
up to 1/2 in.
9/16~1 in.
1-1/16~2 in.
2-1/16~3 in.
3-1/16~4 in.
4-1/16~5 in.
allowances for forced fits
high limit
+.0010
+.0020
+.0040
+.0060
+.0080
+.0100
low limit
+.0005
+.0015
+.0030
+.0045
+.0060
+.0080
tolerance
.0005
.0005
.0010
.0015
.0020
.0020
allowances for driving fits
high limit
+.0005
+.0010
+.0015
+.0025
+.0030
+.0035
low limit
+.0002
+.0007
+.0010
+.0015
+.0020
+.0025
tolerance
.0003
.0003
.0005
.0010
.0010
.0010
allowances for push fits
high limit
-.0002
-.0002
-.0002
-.0005
-.0005
-.0005
low limit
-.0007
-.0007
-.0007
-.0010
-.0010
-.0010
tolerance
.0005
.0005
.0005
.0005
.0005
.0005
allowances for running fits
high limit
-.0010
-.0012
-.0017
-.0020
-.0025
-.0030
low limit
-.0020
-.0027
-.0035
-.0042
-.0050
-.0057
tolerance
.0010
.0015
.0018
.0022
.0025
.0027


Bay Area Dwarf Racing Association 2006