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View Full Version : Question on 5c collet chuck for my New Grizzly lathe.



cybor462
11-05-2006, 01:25 AM
I decided to stay the course and keep my shop. I use it on occasion as much as my body allows. I finally sent the Smithy back (good riddence) and bought a Grizzly. I am so much happier as the difference is like night and day. This lathe cuts dead nuts (2 tenths in 10" so far for those who do not share my dictionary) And the big thing, it does not leak a drop of anything. So many differences I will not bore you with them.
I ordered a 5c collet chuck and installed it. I have never used one so it is virgin territory for me. I was hoping to be able to use a 3' 1" stock 6061 bar and machine this little plug I market and when part is done part it off release the collet pull the bar forward and lock it and do it again.
I can use a small section of bar put in from the collet end but it will not accept the bar thru the spindle from the rear.
Can anyone shed any light on this?

Thanks
Jim

Doc Nickel
11-05-2006, 03:56 AM
First, which model Grizzly? I'm presuming that anything with a 5C-compatible spindle nose (MT5 or better) will have a sufficient through-hole, but it's possible, I suppose, you have a spindle with a sub-1" bore. The solution here is to look. :D

Second, it's typically kind of tough to thread the rod through the collet from the backside, once the collet and closer are assembled. You might undo the collet, slip it onto the end of the rod, and then install both rod and collet into the spindle nose.

Third, I've run across a couple of import or cheap collets that are not bored to full depth- meaning that while the collet is hollow, the bore is not always the same dimension all the way through. I have a 1" import collet that is only bored to 1" to roughly 1.5" depth. It's hollow, but it will not pass a 1" bar through. I've actually used it as a low-precision depth stop before.

Doc.

Spin Doctor
11-05-2006, 09:15 AM
Another problem with 1 inch 5c collets is that if they area threaded on the back side sometimes the thread ID interfers with passing the stock through the collet. Personally I don't like the idea of passing any stock through 5c's with out the use of some sort of supporting bushing, cat head on the back side of the head stock. Its not a lot of fun when that 3/8ths CRS suddenly whips at 1000 rpm. As to design of a supporting bushing at the rear end I guess you're on your own. Us your imagination.

cybor462
11-05-2006, 10:07 AM
Doc its a 4003 36" gap bed. The spindle is 1 7/16 id I think. Either way its much roomier than 1" I think you may have something with the collet, yes these are cheap imports and there is a good chance they are not bored all the way. I will check that.
Spin Doc you are also right as when I push the bar in from the rear it hits and when I remove it there are marks that could be caused by the threads. This could be paired with what Doc says that they are not fully bored thru and thru. I need to research this as one main reason I went with collets other than being more precise but also they will save loads of time with the parts I need to make. I need to find someone with higher quality collets and have them spec it for me so I can compare. As usual I came to the right place for answers. Thanks Guys!

cybor462
11-12-2006, 12:59 AM
Well I found the reason. Your all right. It was the threads. I was not sure why they have id threads as the od threads are the ones used. So I called Grizzly. Very friendly and gave me my answer. They use the id threads to make the collet. That is the only reason for them. They told me to grind them to gain back room. I did it. It was very easy and now the stock passes through them fine.
Thanks all for the info.

ltvTOM
11-12-2006, 01:29 AM
They may have been "Very friendly and gave me my answer" but I
think they may have misinformed you.One use of the internal threads
on the 5-C Cottets are for a Collet Stop .Grizzly sells collet stops!!!
http://www.grizzly.com/products/h6497
Tom

cybor462
11-12-2006, 01:46 AM
Aint that a bite in the a*s. Good thing I only ground the threads off the one collet I am using now. I intend to keep it for this one job which will never need a stop as I feed thru the rear. But good to know. I guess I need to research this stuff without getting info from just one source. Ok now I need to ask why the heck can't they make them so the work will pass thru? Also I only took the a small amount off I do not think the thread is wrecked yet. But thanks for the heads up!

Doc Nickel
11-12-2006, 06:57 AM
My 1" import collet does that. The bore of the collet isn't ground all the way through, so it won't pass a 1" bar. The college machine shop, though, gave me an old Hardinge (we think) 1" collet, that works just fine.

Both are threaded internally for a stop, and the threads don't interfere with the bar.

The other thing I noticed about my import 5C set is that they're ground right on. Meaning that the 1/2" collet, even when not in the nose taper, and loose in your hand, is as close to .5000" as I can easily measure. Ditto the 1", which is right on one inch, to about four decimal places.

Fine and dandy, you say? Nope- I have yet to find any off-the-shelf raw stock anywhere near "nominal". The 1" round aluminum I get is at least five thou oversize. The 1/2" rod closer to 20 thou over. Steel rod, unless it's drill rod, stainless or chrome-moly, can be anywhere from ten under to ten over.

The Hardinge (and other name-brand) collets are ground slightly oversize, to ease insertion and removal of the part.

Doc.

cybor462
11-12-2006, 02:36 PM
Doc you are so right. I guess you get what you pay for. This is my first collet chuck and as you can see I am in the dark as far as how they are. I have the import collet set and yes I had a heck of a time to adjust the collet so I could insert the stock and then have it tighten for machining. Thought it was my stupidity but I guess it is the collets.
I guess I will need to look for better collets.

I saw your link at the bottom of your post. Do you do all the machine work for the parts you sell?
If you do it do you carry liability insurance? I ask because I designed and made flash hider/muzzle brakes for AK47's tested real nice on our Import but when I tried to get insurance no one would write it. Just wondering if you have it and if so where do you get it? Might help me to find it.

Thanks
Jim

alabamaed36046
11-12-2006, 03:27 PM
If your stock is oversize just use an "emergency" collet. It will be set on size with 3 pins. Drill close to size then bore to finish size. Remove ,clean, deburr
then pull the pins out and you are ready for odd size material.
alabamaed36046