ISO Slip Fits

[UofDoboe]

thread404-408838 discussed "standard" recommended press fits with ISO class m6 dowel pins which seem to be by far the most common ISO dowel pins.

Is there a standard recommended slip fit with ISO class m6 dowel pins?

I'm aware that the H7 reamer is the most common, but a m6/H7 fit is a transition fit (at least one sources describes m6/H7 as a "driving fit").
There are obviously a myriad of other ISO hole classes, but not all of these are common and not all have reamers associated with that hole class. Is there a standard / recommended / common fit with a class m6 dowel pin that results in a slip fit? Application is in fixturing with frequent workpiece engagement/disengagement.

 

[handleman]

OK, let's back up one step.

If you are designing jigs with frequent engagement/disengagement, you probably shouldn't be using dowel pins. There are lots of components commercially available (Misumi for metric, Carr-Lane for inch are just a couple) that are designed to be incorporated in engage/disengage jig operations.

 

[UofDoboe]

Acknowledged, and I have used such locating components in the past. Cost and ease of replacing the locating features are a business desire for this fixture, dowel pins are being incorporated instead.

 

[SwinnyGG]

It is possible that assembly of m6 pins into H7 holes will require tools, depending on tolerance stackup of your actual physical parts.

m6 pins are certainly the most commonly available type- with that in hand, you need to pick a fit from the chart and buy the right reamer. Simple.

 

[handleman]

Pay a little more for slip fit dowels (g6) and use H7 holes. Except that there's no telling which side the dowel will stick in. For even more $ you can get 2-tolerance pins (g6 on one end, m6 on the other). Or you can get hardened locating pin bushings that will never need replacement for much less than the labor cost of replacing the wallered out hole from folks trying to beat dowels into it. You can even get slotted toleanced bushings that will allow assembly to the jig independent of how well the dowel pitch was held. What size bushings? H7/g6 gives a nice slip fit. I assume you can do math.

 

[Tmoose]

what are the tolerances on the finished features or processes performed on the "workpieces" ?

I presume you are designing/deciding on the location and fit of the (holes in the removable workpiece, not the holes capturing the dowels in the fixture.