[DATTAMAN]

I need drill and ream Specs For 5 and 6mm press fit in 7075 Aluminum Alloy

Does anyone know where to download a chart for these and other metric press fits...Do not have access to Machinist Bible...Thanks

[cdlenterprises]

The general rule of thumb that I use is the drill size should be 1/64" smaller than the ream size for standard. For metric, I would guess 1/4(.010 inches) to 1/2(.020 inches) of a millimeter smaller for the drill size. Not sure if this was what you were looking for....

[RFB]

DATTAMAN,

If you create an exact 5mm diameter hole and then try to insert a dowel pin with an exact diameter of 5mm then you will have a pressfit or an interference fit. I use a reamer that is a .0005 under nominal diameter and that assures that I will have an interference fit ranginging from zero to minus half a thousandth.

When using a reamer then it must be mounted so that there is no wobble, else it will try to bore versus ream. If I'm forced to use a drill chuck then I use a dial indicator to check for wobble in the reamer mounting. Assuming that the reamer is good then there are other factors that can effect the results of reaming holes. 1: Spindle speed. 2: Chip load (plus chip volume). 3: Coolant (including type of coolant).

Having stated all of the above, reaming holes is not Rocket Science. Do some research for finding the correct speed for the type of material and the reamer that you're working with and then do some test holes. If I'm using a new reamer then I will do some test holes to verify the hole size before using it for the objective purpose.

C4C

[juergenwt]

Dataman_DIN 7157, ISO 286
Tight Press fit H8/x8 up to 24mm, 5-6mm = Hole 0 to +18 /shaft +28 to +46


Medium Press Fit H7/s6, 5-6mm = Hole 0 to +12 /shaft+19 to +27
Light Press Fit H7/r6, 5-6mm = Hole 0 to +12 /shaft +15 to +23

[awhtyp]

hope this helps. these are hole basis.

[awhtyp]

these are shaft basis, which you will use if you have a dowel pin.