Tool Hex Collet Holder

[jcdammeyer]

Yahoo! Canada Post delivered my Square and Hex ER32 collet holders. Now I really didn't need these since I have the 5C spin indexer and eventually will have the harmonic drive with the ER32 collet chuck.
But I read somewhere that sometimes it's handy to have the collet pointing upwards rather than horizontal so I splurged.

Anyway. A small scrap of 1" soft steel turned down in the 3-jaw chuck to 19.5mm for the 19-20mm ER32 collet. Then into the hex collet holder to turn the hex part.

Mistake #1 -- Should have had the flat part of the holder resting on the bottom of the vise. A video I watched on using the collet mentioned that it may not be as accurate to use the corners as the height reference. That turned out to be true. The flats were out by about 0.008" on one of the pairs. The other two pairs were within 0.001".

There is no purpose to the part. Totally just practice. All work was done by turning the MPG knob on the pendant and selecting which axis to move. So a very manual operation rather than CNC.

 

[Six O Two]

Mistake #1 -- Should have had the flat part of the holder resting on the bottom of the vise. A video I watched on using the collet mentioned that it may not be as accurate to use the corners as the height reference. That turned out to be true. The flats were out by about 0.008" on one of the pairs. The other two pairs were within 0.001".

That's fascinating. I have an ER collet block, and it would never have occurred to me that the corners might not be accurate as a height reference. I think I've used it once to cut a hex head and over the very short length of the flats I obviously didn't notice anything odd, but i'll definitely keep an eye on it from now on.

 

[jcdammeyer]

That's fascinating. I have an ER collet block, and it would never have occurred to me that the corners might not be accurate as a height reference. I think I've used it once to cut a hex head and over the very short length of the flats I obviously didn't notice anything odd, but i'll definitely keep an eye on it from now on.

I didn't either until I watched that video. I haven't had a chance yet but I was going to check them out on my surface plate. It's just spent the afternoon and some of the evening playing around making a 21 TPI thread. Just because.

 

[Susquatch]

I didn't either until I watched that video.

I need to watch a video like I need a hole in my head, but.... I am intrigued. I've read before that collet blocks lack consistency and should be purchased in sets. I'd like to know more. Do you have a link to the video?

 

[jcdammeyer]

I need to watch a video like I need a hole in my head, but.... I am intrigued. I've read before that collet blocks lack consistency and should be purchased in sets. I'd like to know more. Do you have a link to the video?

I'll see if I can find it again. I did some testing on mine on my surface plate. Problem with measuring is the nut is larger in diameter than the hex section. If I was going to make one of these I'd have made the distance between flats wider than the diameter of the nut so it could sit flat on whatever. Maybe the higher end units don't have this issue.

But I don't think mine is completely symmetrical.

Found it I believe.

 

[Susquatch]

If I was going to make one of these I'd have made the distance between flats wider than the diameter of the nut so it could sit flat on whatever. Maybe the higher end units don't have this issue.

Thanks for that @jcdammeyer .

The nuts on mine are like yours. I've looked and never seen one that isn't. I suppose a smaller collet like ER20 might be fine unless the blocks are actually smaller too.

I think this business of the corners vs the flats is as simple as the sharpness of the corners. If the chamfer isn't identical, the corners won't work well. Razor sharp corners are not really practical either.

My concern which I didn't explain earlier, is that the collets are not always consistent. No two are the same. That's not a problem for small jobs when only one is needed but there are times when two or three collets are needed. In fact, it came up earlier on this forum - I just don't remember who or why. In that situation, the collet blocks need to be matched. Even if they are perfect as the one in the video seems to be, another one might not be the same. Depending on the accuracy of the job, that might be a problem. Who wants to be shimming a collet block?

 

[PaulL]

Maybe the higher end units don't have this issue.

I've seen 5C blocks that wind up not protruding. ER32 or ER40 would have to be beasts.

 

[jcdammeyer]

They are clearly meant to be held in a vise. I will do some more testing.

 

[PeterT]

I don't think referencing off corners is ever a good idea, be it collet blocks, 123 blocks, gage blocks... The critical dimension is across the flats, not diagonally. As mentioned, any variation in chamfer or round-over is going to affect accuracy. Unfortunately with 6-sided collet blocks it seems like the natural thing to do. Even though the vise jaws are flush to flats, the vertical height (variation) will be a function of the edge chamfer every time the block is rolled to reposition. 4-sided blocks don't have this issue, nor if the collet block was standing up. I guess either use a spin indexer or someone has to invent different angle V blocks with a corner relief if higher accuracy is required.

 

[jcdammeyer]

The reason I ran into that is I had the hex collet holder standing up. Couldn't grip it tight enough and it tipped. So then I turned it sideways. Well when you think about it vertical with the flat to the vise jaws ends up with the edge now referenced to the vise bottom when it's pivoted. And that's when I noticed the hex cutting variation. And that's what was mentioned in that video.