Armory Sponsor
Posted: 1/24/2014 8:18:21 AM EDT
|
I have noticed many machinists use collets to hold projects in both lathes & mills. One would think with all the training I got in school, I would know how to use and what I would need to use them. If anyone could explain to this dummy or point me in the right direction, I would greatly appreciate it.
Thanks, Mark PS: I graduated form Pittsburg State University, Pittsburg, KS. in 1978, so it has been awhile. |
|
Depends what you are trying to do and what machine you are trying to do it on. I use R8 collets for my Bridgeport mill, as that is what is required for the spindle. If not a R8 collet, an adapter.
I also happen to use C5 collets with holders depending on the situation. They come in very handy for work holding on round stock, especially if it needs to be indexed 90,180, 60, or 120 degrees |
|
Quoted:
Depends what you are trying to do and what machine you are trying to do it on. I use R8 collets for my Bridgeport mill, as that is what is required for the spindle. If not a R8 collet, an adapter. I also happen to use C5 collets with holders depending on the situation. They come in very handy for work holding on round stock, especially if it needs to be indexed 90,180, 60, or 120 degrees Here is another dumb question. Does the Morse taper hold the collet in, or do you have to have a holder? I am talking about, say on a Grizzly 4003 lathe. And thanks for your answers, both of you. Mark |
|
Quoted:
Here is another dumb question. Does the Morse taper hold the collet in, or do you have to have a holder? I am talking about, say on a Grizzly 4003 lathe. And thanks for your answers, both of you. Mark Quoted:
Quoted:
Depends what you are trying to do and what machine you are trying to do it on. I use R8 collets for my Bridgeport mill, as that is what is required for the spindle. If not a R8 collet, an adapter. I also happen to use C5 collets with holders depending on the situation. They come in very handy for work holding on round stock, especially if it needs to be indexed 90,180, 60, or 120 degrees Here is another dumb question. Does the Morse taper hold the collet in, or do you have to have a holder? I am talking about, say on a Grizzly 4003 lathe. And thanks for your answers, both of you. Mark Collets generally use a drawbar that pulls them into the taper, thus tightening them around the stock/tool. The friction from the taper locks it in place. Example: for the Grizzly lathe you posted, you would need MT5 (Morse Taper #5) collets. You use a drawbar (I have a construction bolt of the right diameter and a pan washer for my mini-lathe, because I'm cheap and lazy  ) that threads into the back of the collet, and tightens on the other end of the spindle tube. I believe they make adapters so you can use 5C/other collets in the lathe, as well as a quick change attachment. Different types of collets have different advantages/disadvantages - search around on google for collet type comparisons, and you should be able to find more background info than you could want.
|
|
Buuut- don't use a collet on a barrel if you are threading the barrel. Collets register on the OD of the object you are turning. You never want to trust that a bore is perfectly concentric with the OD of a barrel.
But for general turning of round stock they are hard to beat and for production work they are priceless. I got lucky on my lathe and it came with a Royal 5C collet closer already set up. Nice to have when you need it. |
|
Quoted:
Buuut- don't use a collet on a barrel if you are threading the barrel. Collets register on the OD of the object you are turning. You never want to trust that a bore is perfectly concentric with the OD of a barrel. But for general turning of round stock they are hard to beat and for production work they are priceless. I got lucky on my lathe and it came with a Royal 5C collet closer already set up. Nice to have when you need it. Thanks, I was wondering about a chuck marring a barrel too! I am starting to feel more stupid as time passes. I have a lot to learn yet. Thought about taking a class on machining at a local Community College. But that is going to look funny too. Someone who taught Industrial/ Vocational Ed. for 31 years taking a beginner's class. My main field was Auto Tech though. Thank You, Mark |
|
Quoted:
Buuut- don't use a collet on a barrel if you are threading the barrel. Collets register on the OD of the object you are turning. You never want to trust that a bore is perfectly concentric with the OD of a barrel. But for general turning of round stock they are hard to beat and for production work they are priceless. I got lucky on my lathe and it came with a Royal 5C collet closer already set up. Nice to have when you need it. But but......you can use a collet on a barrel for threading as long as you use a collet holder within a 6 jaw chuck. 
|
|
Quoted:
Thanks, I was wondering about a chuck marring a barrel too! I am starting to feel more stupid as time passes. I have a lot to learn yet. Thought about taking a class on machining at a local Community College. But that is going to look funny too. Someone who taught Industrial/ Vocational Ed. for 31 years taking a beginner's class. My main field was Auto Tech though. Thank You, Mark Quoted:
Quoted:
Buuut- don't use a collet on a barrel if you are threading the barrel. Collets register on the OD of the object you are turning. You never want to trust that a bore is perfectly concentric with the OD of a barrel. But for general turning of round stock they are hard to beat and for production work they are priceless. I got lucky on my lathe and it came with a Royal 5C collet closer already set up. Nice to have when you need it. Thanks, I was wondering about a chuck marring a barrel too! I am starting to feel more stupid as time passes. I have a lot to learn yet. Thought about taking a class on machining at a local Community College. But that is going to look funny too. Someone who taught Industrial/ Vocational Ed. for 31 years taking a beginner's class. My main field was Auto Tech though. Thank You, Mark There are a few tricks to holding a barrel without dinging the finish. Some guys will make a nylon or aluminum bushing and chuck on the bushing, some will pad the jaws with leather, lead sheet or copper. I have even seen where a bushing of Bondo was placed around a barrel, turned true and chucked on that. If I am passing the barrel through the headstock the outboard end is supported by a spider and I like to use a piece of annealed copper ground wire, I think it is #4 or #6. Make a ring to go around the barrel where the chuck jaws will ride. This does two things, it protects the barrel from the jaws and it acts as a "pivot point" so as you dial in the breech(outboard) end of the barrel the barrel is not stressed at the jaws. You can actually bend a slender profile barrel if it cannot pivot to a degree. You want to indicate both ends of the barrel. You can also spin a barrel between centers but you want to make a brass or aluminum "spud" that has been center drilled for the live center to register in and have a tight slip fit in the muzzle. This will protect the crown. The actual machining processes are usually straightforward, it is holding your work accurately and with repeatability where the voodoo is used. Setup is also the most time consuming aspect of machining. I have had barrels that I can indicate in five minutes and yet I have had some where I have "chased the needle" for half an hour or more until I was content with it. Take the classes. You will need every bit of experience and education on a machine you can get. |
|
The Grizzly lathe has a MT#5 spindle. You need a MT#5 to 5-c collet adaptor (Grizzly part P4026001). Then you need to figure out how to tighten the thing. Grizzly makes a cam lock drawbar puller that goes through the headstock. I didn't buy the whole thing - I just bought the spindle tube and made a spacer and nut to tighten it with.
Grizzly collet puller edit to fix |
|
Thanks to all of you, I got it now, for a lathe. I really appreciate all the help. That $350 for the collet holder really cuts into my $$, but oh well.
Thanks, Mark PS: I had thought about wrapping the barrel with leather or something with a chuck, but wasn't sure about that. You can bet that I am going to start out on a sewer pipe barrel. |
|
Depending on the tools you have........
A collet holder within a 6 jaw chuck is the safest way. With a collet holder you get a nice even pressure that is nice to the surface of the part. I avoid a 4 jaw chuck due to it being a pain in the ass with uneven pressure on the part. 6 jaws have even pressure and are easier to dial in TIR. An even layer of masking tape will help protect a finish. |
|
On the Grizzly you can just take the chuck off. The Spindle has a #5MT. You just need a #5MT to 5C adaptor - and a means to close the collet. They don't list the parts pricing on the website anymore - but I bought the #5MT to 5C adaptor and the drawbar tube from Grizzly using the part no's off of the cam-lock tightener. The tube is threaded on the back end by - So I made a spacer and a nut so I can tighten the collets from the back of the spindle. It's not as nifty as the cam-lock drawbar - but I have about $130 into it instead of $350.
This is much easier than trying to tighten the workpiece in the collet and collet holder and then trying to get the whole thing centered in the chuck. |
| minimum depends what you want to do. If it's barrels, I'd say min 1 1/8" thru bore. When I decided to get a lathe, I was interested in that but also doing some form1 suppressors. In my case I wanted at least a 1 1/2" thru bore. I looked around for probably a year and a half before finding one within my budget. I looked on craigslist, online, local ads, and auctions. One word of advice though - the machines are the cheap part, the tooling, testing, and measuring equipment add up fast. |
|
Thanks, I have room for a 36" to 40" lathe. I did not think I would live this long when I had my so called shop built. I did not have 220V wired into it. With finished ceilings, it is going to be a bear to get 220 to it. Also, I was thinking of spending less money. I want a new Grizzly G004, but have been looking at the one just smaller than it. It only has a one inch bore. I don't want to limit myself too much. I would like to chamber a barrel, and cut down the dia. of another. Mainly I just want it for something to do on days I am feeling good, or it is so cold I can't get out.
Thanks, Mark PS: I had already acquired quite a few tools & accessories when I had my shop at our place in the country. This was before my heart went south. |
|
I have been thinking about a tapering jig for my G4003 - they want a lot of money for one though. I know you can offset the tailstock, but then to get it re-centered for general use is a PITA.
So I've been thinking of making a taper jig. I wouldn't think it would be all that hard, just need a way to free the crossslide and create a very stable guide rod/bearing. |
Armory Sponsor