Setup for grinding an ER32 collet chuck

Hi,
I put together the couple of last tools I posted here in an application video showing how I have reground a badly manufactured ER32 collet chuck :

https://youtu.be/RKmTH_aD_YE

I tried to explain the rationale in the video subtitles, but the key points are :

- It is a CM2 chuck, and my metal lathe spindle is CM3. So I decided to do it on my wood lathe, which has a really high quality spindle.
Additional, I didn't want to use a CM3/CM2 adapter to put it in the metal lathe, it would introduce more run-out.
Other reason, I try to avoid metal grinding as far as I can on my metal lathe. The wood lathe bed is less sensitive to the grit, a shot of compressed air and everything is clean.

- I used an ER collet to setup precisely my 8° angle. To hold it in the spindle I chucked a ground 8mm bar in a good quality 8mm pull-back collet.

- I needed a stone larger than the ER11 chuck of the HS spindle. The only one I had was this ball shaped white grinding bit. But it was not well centered so I started by trueing it up in the spindle, using a diamond tool

- Obviously, with my setup, I miss the transversal slide, to take passes. As I show on the video, I have clamped on the bed two parallel cawls to keep the tool rest base perpendicular to the axis and thus avoiding to loose my angle setup. To take a pass, I just loosen the crank, and lightly tap with the plane hammer. It is low tech, but works pretty well.


Finally, I am pretty happy with the result and again, this HS spindle is really the killer tool ;-)

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Thanks Christophe Mineau! We've added your Collet Chuck Grinding Setup to our Machining category,
as well as to your builder page: Christophe Mineau's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-collet-chuck-grinding-setup"> <img src="/uploads/170225/homemade-collet-chuck-grinding-setup.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-collet-chuck-grinding-setup">Collet Chuck Grinding Setup</a> <span> by <a href="http://www.homemadetools.net/builder/Christophe+Mineau">Christophe Mineau</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/chuck'>chuck</a>, <a href='http://www.homemadetools.net/tag/grinding'>grinding</a>, <a href='http://www.homemadetools.net/tag/collet'>collet</a> </div> </div> </div> </div>
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Looks like it worked great, looks like that new high speed spindle worked out just fine for you, just goes to show you that there is more than one way to skin a cat

I need to do that to my er32 x R8 collet chuck that is almost useless with its run out. I just make the tool post holder for some old HF grinder I did not use for anything else.

Quote:

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Originally Posted by Christophe Mineau

It is low tech, but works pretty well.
Finally, I am pretty happy with the result and again, this HS spindle is really the killer tool ;-)

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I've noticed that myself too. Wood lathes can have great spindles, and HS spindle would be flawed from the get-go without. Good spindles share a common trait. That is dispersion, distance between bearings, in a proper housing.

Christophe's done it again! I like the admission of low-tech, pointing out tech isn't always direct or efficient. It's best at filling cubicles. And advertising; don't know about anywhere else, here many ads love the word 'technology' in products. Evident tech was used in the overall process; but not resulting actual product. Hairspray or cosmetics? Nope, Chemistry. Men's multi-bladed shaver? Nope, Design. Cell Phone? Maybe, but not if Ergonomics or Interface fail.
I regard use of the word itself as hype, just misspelled. Like "Kids, it's FUN"! rarely turned out so.

Hello,
I'm researching to buy a 6-jaw chuck for my lathe, I read the article about wood lathe chucks and it says that I should buy a 3-jaw chuck instead of 6-jaw chuck. I've never used 3-jaw chuck before, can anybody confirm if a 3-jaw chuck is the best choice?
Thanks

Article is wood lathes, are you running a metal working machine with wood? That's not uncommon at all. I turn PVC pipe often, which by the way machines nicely.
A six jaw is rather like a collet, more completely 'encircling' a part, regardless the material. They cost more, mainly why they aren't more common, along with some aren't reversible or master style jaws. Jaws are a big consideration, and vary with what different people work on.
At any rate 6 jaws distribute clamping pressure at least twice that of a 3 jaw; not more pressure, EVEN pressure. Imagine thin tube in a 3 jaw. Those 3 points of contact are separated by 120 degrees, enough tightening to grip and resist ejection can deform the tube past elasticity, that's a collapse.
Better duck, here she comes.

Adding to what Toolmaker 51 said about thin tube I don't have a 6 jaw and would still do this even if I had one for machining thin-wall tubing when ever possible I make a snug fitting plug to insert in the tube then when I chuck the tube in my lathe the plug will keep the tube from deforming allowing for much better clamping from the jaws.
I got into the habit of doing this because I used to have a pipe profile cutting machine that had a 5 jaw chuck which had a range form 55 mm through 600 MM by reversing the jaws when cutting shapes in any 4 mm or thinner tubing with a diameter greater than 100 mm we made plugs for those tubes or cap welded the end being chucked since the machine reversed rotation abruptly while the plasma torch swung in wild arcs it could make up to a 3000 mm cut in less than a minute on 3 mm thick or less and when dealing with a 12 meter long 600 mm diameter tube only 2 or 3 mm thick you needed all of the positive clamping force you could get
Using plugs on a metal late just seemed to be a good idea to implement especially for production work

Quote:

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Originally Posted by Frank S

Adding to what Toolmaker 51 said about thin tube I don't have a 6 jaw and would still do this even if I had one for machining thin-wall tubing when ever possible I make a snug fitting plug to insert in the tube then when I chuck the tube in my lathe the plug will keep the tube from deforming allowing for much better clamping from the jaws...Using plugs on a metal late just seemed to be a good idea to implement especially for production work

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Another way are bushings, carefully bored to tube OD and split on one side, and cut some what on the other 180...
As usual, click the pic. Attachment 18714

Thank you, Christophe. Your information is very useful and instructive. I suspect I'm going to need to qualify the best spindle in my shop. I suspect it is in my old Jet milling machine. Mounting a suitable spindle grinder on the mill table with it's limited vertical space will be a challenge.

Hi Christophe,
A good idea to use this way, and to make this video, it is a situation very commonly found with inner conical parts, often the broach cone with W20 is damaged and need such a solution.
Have a nice day.
Pierre

Hi Christophe,

I would not have thought of using a wood lathe but with the excellent precision in the spindles, the technique produced excellent results.

I had a similar situation with a hardened steel ER16 collet chuck I bought on eBay for my 3" swing Unimat and discovered it had 0.003" (0.076 mm) TIR. I decided to make my own ER16 collet chuck. I initially created the chuck using my 12" swing geared head lathe and then finish grinding it on the Unimat SL 1000 (see for the grinding http://www.homemadetools.net/forum/u...6880#post67090 and the first version without grinding at http://www.homemadetools.net/forum/e...0273#post57039 ). I measured the ground TIR at 0.0005" (0.013 mm) with an almost new collet and gage pin and was pleased with the results (the TIR on the inner surface of the collet chuck was 0.0001" (0.003 mm) but it is the combined collet and chuck TIR that is important).

After the success with the homemade ER16 collet chuck, I used the Unimat grinding technique on the chuck bought on eBay. I was surprised at the improvement to be TIR of less than 0.001" (0.025 mm) but it took too much grinding time to remove the hardened steel from the commercial collet chuck for this level of TIR as compared to just making the collet chuck from scratch.

Regards,

Paul