Quasi-involute V-block

[Peter Sanders]

Hi Marv

While I like your line of thinking, I think you have taken a little bit of "poetic license" with the larger vee of the involute shape. What you really gain with this shape is a "lower" or shallower vee block (which of course may be an advantage). Given a true vee block with the same width vee as the top of the involute vee, the tangent of the true vee block would provide a more secure holding position and power than the involute vee. The curved sides of the involute vee will not be a true tangent as in the true vee block. Effectively you have two "circles" pressing against each other.

If you were to reduce the involute vee to the same width as the smaller vee shown in your images, I think the holding power of the involute vee would be of concern. In any given vee width, most nominal diameters would sit much deeper (more secure) in a true vee block than an involute vee.

Kind regards

Peter

[Ed Weldon]

Once you have an involute cutter the V block making gets easier although a corner rounding end mill will work and produce very acceptable fixtures. About how to find a cheap cutter? Take a look at eBay. Lots of prices run under $20, often a lot under for oddball pitches and cutters that were beyond practical resharpening for a professional shop and are now remnants of a box of shop scrap in the hands of a dealer in used tools. You may still need to make an arbor to hold the cutter in your spindle but fiddly accuracy or perfect key slots are not needed for this application as long as you take your cuts with a slow feed to accommodate the teeth on the high side of the cutter that are doing the work.

[thevillageinn]

Thanks Marv for the idea, and Jon for bringing this thread back up in the summary email. What I'm also rather interested in is the local aircraft surplus supplier...could you...would you...dare you... share contact information?
Thanks-
-Dan

[mklotz]

Thanks Marv for the idea, and Jon for bringing this thread back up in the summary email. What I'm also rather interested in is the local aircraft surplus supplier...could you...would you...dare you... share contact information?
Thanks-
-Dan

Sadly, the liquidator closed shop a long time ago. The millenials don't make anything so they don't need stuff with which to not make it.

[thevillageinn]

Sadly, the liquidator closed shop a long time ago. The millenials don't make anything so they don't need stuff with which to not make it.

Bummer. It can be tough to be in business these days, particularly for these niche shops that aren't supported by nationwide presence and major internet sales.

Well, if any hang on, I'd love to know about them before they are gone. I'm in Orange County but regularly travel the entire southern California area for interesting finds or good suppliers.

[volodar]

"R x sq.rt(1x1 + 1x1) = 1.414141414 x R."

Hi Tony,

The chord length is indeed R root two. However, root two is irrational, thus cannot be represented by a repeating decimal. Its value is 1.41421... with never a repeating sequence of digits. This would make the contact points 0.70710678...D apart, still irrational, so 70.711% D rounded. You're close enough!

[tonyfoale]

"R x sq.rt(1x1 + 1x1) = 1.414141414 x R."

Hi Tony,

The chord length is indeed R root two. However, root two is irrational, thus cannot be represented by a repeating decimal. Its value is 1.41421... with never a repeating sequence of digits. This would make the contact points 0.70710678...D apart, still irrational, so 70.711% D rounded. You're close enough!

Of course you are quite right. When I write the sq.rt(2) I always do it correctly but when I type it I just go "one-four, one-four....." several times with two fingers without counting. Same with its inverse "Oh-seven, Oh-seven.....". That's a habit I need to get out of.