Collet fixture vs blocks?

[intjonmiller]

I've been looking at buying a set of 5C collets, collet blocks, spindexer, etc. to complement my small mill setup, and someday my lathe with the addition of a 5C collet chuck. But as I look at the various package deals and individual components I find myself wondering about the horizontal/vertical collet fixtures. I don't recall ever seeing one used in any of the numerous YouTube channels I watch almost religiously.

When would someone use one of those as opposed to a collet block in a vise? What are the advantages and disadvantages either way? Is it even an either/or situation or are they more different in use than I realize?

It seems to me that the collet blocks have inherent indexing functionality that is absent in the fixtures, while the fixtures are more precisely and quickly repeatable than the blocks for runs of identical parts. Does that sound about right? What else?

If it makes sense I'll buy both, as neither are terribly expensive, but if that repeatability is the main benefit I may just skip the fixture.

Thanks!

 

[Bob Korves]

The answer is obviously to get them all, Jon! Collet blocks are great, as long as you only want to do angles that they provide (you can use angle blocks to extend their usefulness into tapers.) Spindexers are good for a lot of things, but are usually set up horizontally, difficult to make them work vertically on most machines, and are limited to one degree increments (angle blocks work here for tapers, too.) Both of those can be cheap to buy. There are various other collet fixtures and indexers, some designed more for production work, and often quite expensive. Then there are rotary tables and dividing heads, again more expensive but can divide to lots of different increments accurately. I use my collet blocks much more often than anything else. Now that I have a surface grinder the spindex will probably see more work...

 

[Dan_S]

When would someone use one of those as opposed to a collet block in a vise? What are the advantages and disadvantages either way? Is it even an either/or situation or are they more different in use than I realize?

It seems to me that the collet blocks have inherent indexing functionality that is absent in the fixtures, while the fixtures are more precisely and quickly repeatable than the blocks for runs of identical parts. Does that sound about right? What else?

Collet blocks are good if you have one to a few parts, and are only working horizontally. Using them vertically is a challenge unless you have really thin parallels, because the clearance between the nut and the sides of the block in minimal.The following process is what it is like to use blocks and shows why it can be slow if you have a lot of parts to do.

1. assuming you already have the part in the collet, and the collet in the block with the nut on you have to clamp the block in the vise so you can lock the nut down with a spanner wrench.
2. un-clamp the vise
3. position the block as needed and re-clamp the vise
4. machine one side of the part
5. if are machining multiple sides of the part, you need to do steps 3 & 4 several times.
6. do step 1 in reverse to swap parts.

an indexer takes longer to set up, but is usually way faster to use for multiple parts.They usually have one lever to clamp/un-clamp the collet, and one lever to index it. Check this video by Stefan Gotteswinter, he shows how to index a fixture at about 2:30.

spin-indexers usually only work horizontally, and are designed more for really fin increments.

 

[BGHansen]

I have square and hex index blocks for 5-C collets; they are great! I use them in the mill vise all of the time. Go through the POTD thread at just about anything under my name and you'll see them in use.

Don't have a spin indexer (yet). I believe those are more for use on a surface grinder than a mill. I've read some comments here recommending not mounting a spin indexer on a mill because of lack of 5-C collet gripping power.

Bruce

 

[intjonmiller]

The spindexer would be used on my grinder as well. The main use, for me, on the mill would be for indexing drilled holes around a part, not heavy milling.

I had forgotten about that video of Stefan's, but I am just talking about the basic fixture that mounts the collet horizontally or vertically, with no other indexing functionality.

Like this: 5C Cam Type Collet Fixture https://www.amazon.com/dp/B0007Q3G44/ref=cm_sw_r_cp_apa_SYATybKTYSNEQ

 

[Dan_S]

Like this: 5C Cam Type Collet Fixture https://www.amazon.com/dp/B0007Q3G44/ref=cm_sw_r_cp_apa_SYATybKTYSNEQ

so the main benefit of that one is if you are going to do one op on a lot of parts. Think mill a flat for a set screw, or drilling a hole.

I only have blocks for the mil, and if I was going to purchase something more, it would be a fixture like Stefan has. Import Spin indexers are so cheap, I consider them more of project specific tooling, by that I mean I'd only by one if i needed it for a specific project.

The best way to spend you money is buy good quality collets.

 

[bfd]

I use my collet blocks on my mill mostly nothing better for a quick hex or square on a part I am making bill

 

[wawoodman]

I finally pulled the trigger, and bought a set of blocks and a starter set of 5C collets. Don't need them now, but I'm sure I will.