OT kinda but machine related ER collet blocks

I raided my piggy bank to buy a pair of ER collet blocks (hex and square) for the milling machine. The ONLY place that sells them is Arc Euro in England. I've looked.

I bought from Arc Euro expecting 2-3 weeks for the shipment to wend its way over 121 degrees of longitude. I ordered over the weekend I got a shipping notice Mon AM and just now (Wed 10 AM) received them from the FedEx guy. 48 work week hours, dock to door.

No customs declaration. They must have a US based fulfullment center. They shipped so quick my check card account hasn't yet been debited for the $67.79 price incl shipping

They look well finished and workmanlike and caliper right on the button but only an hour on the granite with a DTI will quantify their accuracy.

Anyway I'mm a pleased recipient.

Forrest, when you get the opportunity, I'd be interested in the concentricity of those blocks. I.e., variation in distance of collet centerline to each face. That's a no-spec dimension in the cheap 5C collet blocks, and they can vary wildly.

Hi Forrest,

Looking at the same blocks. Really interested in the accuracy , too. Lets us know if you have the time.

Thanks ! Brian

There is a business in Australia selling them as well. I bought a couple and am pleased with them for quick and dirty jobs..

Interesting that they are Stevenson's brand.
Could Sir John be crankin' them out in his shed?


Rex

bjorn toulouse said:

Interesting that they are Stevenson's brand.
Could Sir John be crankin' them out in his shed?


Rex

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His design, UK or Australia. 'Designed by' credit implies he is NOT actually making them.

Thanx for throwing a bucket of reality on my feeble attempt at humor.
I was pissed, initially, but then I realized that you can't help yourself.


Rex

Forrest, do you have a link that you ordered from?
What I found appears to be their home site and not of US origin, and they show their ER32 blocks out of stock.

i would be very interested in how you would check them for concentricity on the plate.

metalmaster10 said:

Forrest, do you have a link that you ordered from?
What I found appears to be their home site and not of US origin, and they show their ER32 blocks out of stock.

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I searched and found only one supplier. So I chump[ed and I ordered my ER 40 collet blocks ("fixtures" in Brit speak) June 6 from the only seller. ArccEuro

ER Collet Fixtures - Arc Euro Trade

thinking "well. I can while away three weeks going something..." but the collet fixtures arrived 6/13 - a mere week. No customs sticker so I imagine the order was shipped from a domestic fulfillment service.

How do you check concentricity from a flat? Use traditional shop gadgets. Specifically a 3/4 dia 4" long dowel pin, a collet, and a pair of V blocks. Make sure of cleanliness etc. Assemble pin in collet and install in block. Hand cinch as you wring the pin in collet to settle any errors while drawing up the collet nut.

First mike flats for parallelism,

Check indexing on Sine bar.

Rest ends of pin on V blocks. mount sensitive DTI in height gage, check accessible part of pin on both ends for parallelism to surface plate.

Number each flat.

Orient first flat on collet block parallel to surface plate and scan for a good zero over the whole surface. Keep note of readings' flat no's etc. Scan each flat in turn and note readings. Reverse collet block and installed pin on V blocks and check again.

If you want to be anal about it slack nut enough to rotate the collet and pin 180 degrees, re-snug the collet nut and check concentricity again..

That's my method but I confess to being slack and lazy. So fat I miked the flats.

The above will work but I made it deliberately complicated. Anyone got a simpler suggestion? You hot shot regulars let the noobs and not so experienced take the first shot this first day..Let them flex their mental muscles until 6/18 midnight PDT.

dian said:

i would be very interested in how you would check them for concentricity on the plate.

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"To be confirmed" by he who HAS them, but from the photos, it looks to me that in each size, a conventional nut extends beyond the flats of the body.

Ergo, perched atop a 1-2-3 block or such so as to clear the nut?

Bill

you will be checking five things at the same time: collet block, collet, nut, roundness of pin and straightness of pin (assuming the v-blocks are perfect). you would have to rotate the pin in the collet and for each position rotate the collet in the block and tighten the nut each time. i would be there all day and know nothing in the end. its a job for a machine.

dian said:

. its a job for a machine.

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General truism w/r tooling. One either trusts the maker, ELSE finds they cannot, and moves-on.

I've learned to buy NEW, even if second-tier, rather than used, potentially worn or abused, first-tier ... or it was when NEW .... only.

These goods should be fine right outta the box until proven otherwise in ordinary USE.

Bill

So few takers? Monarchist was close. The V-block method works but it's a labor intensive smoke screen. Its more efficient to reference from the flats resting on a parallel and check across the pin than reference from the pin in V-blocks and noodle in the flat.

Yes, the collet nut is larger than the square or hex across flats so it has to be set on a parallel or 1-2-3 block. The weight of the nut may make it tippy. Bias the pin's extension out the back for balance. Assemble and check the upper flat for parallel each in succession, then over the pin at each end. Release the collet and rotate the collet and pin as a unit in the bore 180 degrees and re-grip. Recording readings, right? Repeat the test.

If error values repeat from flat to flat, the collet body has the whole error.

If the error repeats but rotated 180 degrees the collet and pin has the whole error. In between takes detective work.

If your max error is 0.0005" TIR, your collet/block assy is exceptionally accurate.

About 2007 I suggested to a tool manufacturer that ER collet blocks might be a useful product to add to their offerings, especially since they were already making ER collets/chucks. I guess they decided otherwise, so it is interesting to see that someone else thought they could be useful.

They seem to make a lot of sense for someone who has a bunch of ER chucks for a mill and doesn't see much need to stock up on a full set of 5C collets just to use for collet blocks.

cheers,
Michael

Michael Moore said:

About 2007 I suggested to a tool manufacturer that ER collet blocks might be a useful product to add to their offerings, especially since they were already making ER collets/chucks. I guess they decided otherwise, so it is interesting to see that someone else thought they could be useful.

They seem to make a lot of sense for someone who has a bunch of ER chucks for a mill and doesn't see much need to stock up on a full set of 5C collets just to use for collet blocks.

cheers,
Michael

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Not so sure. One usually has 5C 'anyway' [1] for so many things 'coz they are relatively cheap, ubiquitous, readily available in hex and square.

For some of the uses a block applies, to, the rear-pull closing, no nut to get in the way OR be subject to - for example - grinding grit - is in favour of the 5C. ER collapse range reduces needed COUNT of collets, and ER40 goes larger that 5C, but still..

If/as/when I really NEEDED and ER 40 block, I'd prolly be as well-off to fab one that accepted a 3/4" straight shank and just use one of the store-bought ER with that tail.

Bill