Step block question

[WobblyHand]

I measured my old set of blocks with the following results. step pitch, .1253"/step; horizontal change, .0619"/step,; vertical change, .1090"/step; and calculated ramp angle 29.56º.

In use, the angle of the step ledge probably isn't too important as when used properly, the clamp would be laid flat on the clamped surface and the clamp moved to the next step up. This results in just one step being truly engaged. The step pitch is the most critical feature but even that can be off slightly and still have the blocks function.

I'm not surprised by those numbers. The ramp angle is not 30 degrees, but slightly under. Of course there's tolerance to deal with. I just looked at two different pairs (different heights) and the angles are different enough that the resultant top surface is not parallel to the base if blocks are mixed. Don't know if that's because cheap import or tolerance issues.

The numbers I used today to make the steps are quite close to being a match to the blocks I have. Considering the number of teeth there are, I don't think the cumulative error on the fifth tooth is sufficient to warrant a redesign. If there were more teeth, or I was manufacturing product, perhaps I would alter my design. Think I will enter a note in design file stating that it's not a perfect fit.

 

[RJSakowski]

I'm not surprised by those numbers. The ramp angle is not 30 degrees, but slightly under. Of course there's tolerance to deal with. I just looked at two different pairs (different heights) and the angles are different enough that the resultant top surface is not parallel to the base if blocks are mixed. Don't know if that's because cheap import or tolerance issues.

The numbers I used today to make the steps are quite close to being a match to the blocks I have. Considering the number of teeth there are, I don't think the cumulative error on the fifth tooth is sufficient to warrant a redesign. If there were more teeth, or I was manufacturing product, perhaps I would alter my design. Think I will enter a note in design file stating that it's not a perfect fit.
View attachment 403219

I remeasured my two sets of blocks, this time using 36 steps and my micrometers instead of calipers. The first set, one which came with my RF30 clone about 40 years ago , I measured a step pitch of .12497 and a ramp angle of 29.87º. The second set, which I purchased with my Tormach mill 10 years ago, I measured step pitch of .12483 and a ramp angle of 30.228º.

Your design as illustrated above will work fine. The most important feature is that the clamp not slip off the step block in use and you have accomplished that.