New 4-jaw mistake!

[jgarrett]

I just purchased a new 4-jaw 6" chuck from LMS. My theory is always buy as big as will fit and what you can afford. No problem with LMS, they are great.
When I opened the box I know I had made a mistake. WAY too big for my needs. I probably should have gotten the 4". Most of what I am doing now is small steam engines and the little Unimat 4-jaw I was using just didn't cut it. I will keep the 6" and buy a 4" later. I guess the moral of this purchase is "bigger is not always better"
I have a Maximat V10-P.
Machining the back plate and drilling the holes is another complete story, but it fit and a Starrett Last Word DTI shows less than a needle width TIR.
Julian

 

[Tin Falcon]

what people forget is the chuck diameter grows as soon as anything is put into it. the jaws have to move out to accommodate the stock. Also lathes are rated as swing over the bed. Swing over the compound is less.
Tin

 

[Cedge]

Julian
Get in touch with LMS and talk to them. They've been pretty good in the past about helping a customer out with such mistakes. I know they've swapped out an item or two I've bought in the past that wouldn't work with my machines. They're good people and very much oriented to maintaining good customer relations, even when things sometimes aren't quite their fault.

I run a 5 inch 3 and 4 jaw chuck on my 7x14 MicroMark Lathe with great success. However, it's as large as you'd ever want to run on such a small lathe. Any bigger would be striking the ways when the jaws are extended. I lose a little cross slide access beneath the chuck, but its more than made up for by the increased stock diameters I can turn.

Steve

 

[rake60]

I wish LMS had a 3" 4-jaw that would fit my 9 X 19 lathe.
I love the rigidity of the machine but it's actually too big for many of the
parts I make.

Rick

 

[tattoomike68]

When I bought my smithy I did get an 8" 4 jaw and while it fits fine its just heavy and bolting it on is a pain. A 6" would have been a better choice for me but its mine now.

Also if I want to run it at higher speeds I have to get it spinning by hand then kick on the power or it blows the circut breaker. :lol:

 

[jgarrett]

I feel sure that they (LMS) would exchange it for the 4" but postage is the problem.
Figure it would cost me about $40 to exchange it. Bed clearence is not all that bad. If I have to open the jaws so far that it hits I figure it's too big for me to be turning anyway. I feel sure that I can use it for a lot of things just not small steam engines.
Thanks for the advise.
Julian

 

[1Kenny]

What is the opinions of a 3" 4 jaw. I am covered with a 6" 3 jaw and a 8" 4 jaw but they won't hold anything real small. At one time I had a lathe with a 25" 4 jaw and would mount the smaller chucks in it. I was thinking a little 3" would work in the lathe and on a RT.

Kenny

 

[lugnut]

I just recently bought a small 4” RT from LMS. I also bought a 3” 4 jaw and a 3” 3 jaw chucks for the RT. They are low quality stuff but seem to get the job done. The biggest problem I see, is swarf from the mill gets down in the gears of the chucks and clogs them up all the time. So I’m constantly having to disassemble them and cleaning them out. Still beats not having them at all.
Mel

 

[tattoomike68]

I just recently bought a small 4” RT from LMS. I also bought a 3” 4 jaw and a 3” 3 jaw chucks for the RT. They are low quality stuff but seem to get the job done. The biggest problem I see, is swarf from the mill gets down in the gears of the chucks and clogs them up all the time. So I’m constantly having to disassemble them and cleaning them out. Still beats not having them at all.
Mel

Pack the jaw slots and bore with paper towels. shop vac the grunge off and pull the paper and most of the problem grunge is gone.

 

[Bogstandard]

Kenny,
I think I posted this somewhere else on the site, but I can't find it, so here it is again.
To hold small stuff (or even tiny) just turn up a split bush, it doesn't need to be anything fancy, and hold your small bits in that. Saves having too many chucks lying about. What will do a lot will also do a little, but not the other way round.

That is a 1mm crankpin.

John

 

[macona]

Kenny, if you are doing small I recommend to invest in collets. Way more accurate than any three jaw. And will not deform the part and usually not even mark it.

I have 5C's and they are real nice.

 

[lugnut]

do they make collets with square holes in them?
Mel

 

[mklotz]

do they make collets with square holes in them?
Mel

Yes and they're handier than a shirt pocket when working with square stock. You can also get collets with hexagonal holes.

 

[1Kenny]

Macona,

I have collets for my lathe but hardly ever use them. Most of the time the 4 jaw is on it as it is easy and fast for me to use. I was thinking about the 3" 4 jaw to use as a workholder on the mill too.

Kenny

 

[Bogstandard]

The advantage with 5c collets is the amount of different fixtures you can get for them to use on your miller, as well as the improved accuracy on your lathe.
I use a collet block set. Just drop them into your miller vice and you can cut squares, flats on shafts and hex heads in a matter of minutes.
http://www.chronos.ltd.uk/cgi-local...__41.html#aSMA0321_2c_2c_2c#aSMA0321_2c_2c_2c
For hex bar I find that using just a straight round collet holds them very accurately, just have to make sure the corners of the bar aren't in line with the collet slots. I also have expanding mandrels, but they are limited to what you can hold unless you want to machine them to size.
If you go for one of the cheaper chucks they can be a bit dubious as regards to build quality, even though I did a perfect fit to the backplate the nose where the collet fitted was out by 0.0002", so I reground it with my toolpost grinder, and since then zero's all round. But you must ensure that your chuck mounting to the lathe is perfectly clean whenever you change chucks, and the collets are spotless, otherwise a tiny amount of swarf will kick it out of alignment and defeat the object of a high precision chuck.
For hand finishing small parts, they are ideal as there are no sticky out bits to knock your knuckles on when it is turning.
I just wish I could get my stuff from the States as 5c equipment is half the price of what it is in the UK.

John