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Lathe for gunsmithing??

 
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  #8  
Old 12-27-2010, 04:14 PM
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Join Date: Dec 2010
Posts: 18
Re: Lathe for gunsmithing??

Some people will say that a 55 chevy is better than a brand new car-heavier metal and no cheap plastic etc. The same with old lathes cabbaged out of some machine shop after years of use and abuse- Yes, if you can find a 25 year old Colchester with little or no wear, buy it. But most old machines will have wear and need either repair or a good operator to counteract the wear when machining. I looked for a good old lathe and didn"t find one that would be good for a rank beginner-but I had the determination to learn to fit and chamber my own- Ended up buyinga new low priced Chinese benchtop 12-36. Was fun to start learning on but quickly I wanted a better quality lathe. The shortcomings of this machine soon appeared. Had backgear and chattered when reaming. Spindle hole was less than 1"1/2 dictating 1.5" barrels had to be chambered out on bed in steady rest, which is not the way I prefer to chamber-A steady rest is basically a 3 jaw chuck that cant be indicated in--however, through the headstock with a 4 jaw or 6 jaw can be centered zero. I use an indicator with a long tip and reach in to throat area and indicate on lands and grooves. Generally a heavier machine is more rigid than light machine-A 14-40 with single phase is a good gunsmith lathe size-and usually the better quality the higher the price, but I think a new machine is better for many reasons and unless doing production work, most will be satisfactory

Last edited by jarnold37; 12-27-2010 at 04:15 PM. Reason: misspell
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  #9  
Old 12-27-2010, 06:13 PM
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Join Date: Oct 2006
Posts: 466
Re: Lathe for gunsmithing??

I am on my 4th lathe in 8 years for gunsmithing. The last one, the one I got since this thread stared has cut threads and chambers for 4 rifles.
It is a Precision Matthews PM1236 $3k + $1k DRO.
I finally have a lathe that is better than I need for everything I do.


I am still on my first wife after 34 years of marriage.
But she was my 40th girl friend.

There is a great similarity between getting married and buying a lathe.
There is the idealistic phase, the disillusion stage, then the effort to move her and her stuff out.
Hopefully you learn from each relationship, what it is you want, and what are you willing to do to get it.
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  #10  
Old 12-28-2010, 02:29 PM
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Join Date: Jun 2010
Location: greenwood, IN
Posts: 3,606
Re: Lathe for gunsmithing??

I'm from the school that says you get what you pay for. The best lathe used out there is of course a Monarch. But most are big three phase machines. The most accurate lathe ever produced is a Monarch Double E with the Hardingh be a close second. A good Southbend will do anything you ever want to do without too much of a problem. There's also the Colechester from England and a few others here and there. Watch the government surpluss auctions. That's where the bargins are at.
gary
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  #11  
Old 12-28-2010, 03:13 PM
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Join Date: Oct 2006
Posts: 466
Re: Lathe for gunsmithing??

The relationship between a lathe's accuracy and a long range hunting rifle's accuracy is tenuous at best.

If my 7mmRemMag chamber that is 0.0050" off center of the lathe when done, shoots 0.75" groups at 100 yards, then the difference between a $3K Chinese lathe that has 0.0005" runout and a $75k Monarch that has 0.00003" run out, is ...


$75K - $3K = $72K cost change
[.0005"] [.75"]/[.005"] = .075" Chinese group size
[.00003][.75]/[.005"] = .0045" Monarch group size
.075" Chinese group - .0045" Monarch group = .0705" group improvement with Monarch
[$72K Monarch upgrade]/ [.0705" Monarch group improvement] = $1,021,276.60 per moa improvement.

What does it all mean?
Ammo concentricity is important, as the ammo is inserted with random rotational orientation, but chamber concentricity has constant rotational orientation, and so is less important. This often confuses gunsmiths, and they dial in both ends of a barrel to get the bore concentric and parallel with the lathe spindle to within .0001".

I have done it.
Don't fall for that accuracy ritual.
You can get beat at the range in a match with someone who chambered on a drill press.
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  #12  
Old 12-28-2010, 04:21 PM
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Join Date: Jun 2010
Location: greenwood, IN
Posts: 3,606
Re: Lathe for gunsmithing??

Quote:
Originally Posted by Clark View Post
The relationship between a lathe's accuracy and a long range hunting rifle's accuracy is tenuous at best.

If my 7mmRemMag chamber that is 0.0050" off center of the lathe when done, shoots 0.75" groups at 100 yards, then the difference between a $3K Chinese lathe that has 0.0005" runout and a $75k Monarch that has 0.00003" run out, is ...


$75K - $3K = $72K cost change
[.0005"] [.75"]/[.005"] = .075" Chinese group size
[.00003][.75]/[.005"] = .0045" Monarch group size
.075" Chinese group - .0045" Monarch group = .0705" group improvement with Monarch
[$72K Monarch upgrade]/ [.0705" Monarch group improvement] = $1,021,276.60 per moa improvement.

What does it all mean?
Ammo concentricity is important, as the ammo is inserted with random rotational orientation, but chamber concentricity has constant rotational orientation, and so is less important. This often confuses gunsmiths, and they dial in both ends of a barrel to get the bore concentric and parallel with the lathe spindle to within .0001".

I have done it.
Don't fall for that accuracy ritual.
You can get beat at the range in a match with someone who chambered on a drill press.
I don't see where your going. My statement if you took it into context was simply you get what you pay for. I also made the statement that you often can find great buys at government surplus auctions. These are known as DIAPC machines, and are rebuilt before ever being returned to the government. Secondly you can also get great deals at the shipyard auctions (full of Monarch Double E's by the way). I've seen these lathes in great shape go for well under a thousand dollars (I know of two that went for less than $500).

I'm a machine builder by trade with an engineering degree, and I do have a good idea as what makes up a good piece of equipment and a boat anchor. I still make a few dollars whenever I want to undoing the best buys out there. As for accuracey specs, you can put them in three levels. You already know whats in the bottom of the stack and I told you what was at the top of the pecking order. So you have to realize what you want, and also will it do what you want. If your gonna play with some of the exotic materials you better have something that will. You won't get that in an Asian piece of equipment, and use it much. (even an Okuma has a hard time dealing with that stuff) Guess that's why the Japs are buying all the good used hand lathes they can get their hands on (mostly Monarchs)

P.S. you ain't gonna find many Chinese lathes that will ream a chamber within .002" and still have it round
gary
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  #13  
Old 12-28-2010, 05:09 PM
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Join Date: Oct 2008
Location: Kodiak, Ak
Posts: 357
Re: Lathe for gunsmithing??

My Favorite is a Monarch and with the new DRO it is pure joy to use. Currently the Southbend has a hiccup from time to time and when it happens it puts a .010 radius line either inside or outside when it happens. Needs work so I am currently not using it.

I won't buy Chinese as their warranty's and what their machinery will do most time are not the same. Besides, America needs our money. Those shipping costs we can in many cases attribute that to Unions. I either hauled my own or found a friend to haul.

Neal
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  #14  
Old 12-29-2010, 11:43 AM
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Join Date: Jun 2010
Location: greenwood, IN
Posts: 3,606
Re: Lathe for gunsmithing??

Quote:
Originally Posted by hammertyme View Post
My Favorite is a Monarch and with the new DRO it is pure joy to use. Currently the Southbend has a hiccup from time to time and when it happens it puts a .010 radius line either inside or outside when it happens. Needs work so I am currently not using it.

I won't buy Chinese as their warranty's and what their machinery will do most time are not the same. Besides, America needs our money. Those shipping costs we can in many cases attribute that to Unions. I either hauled my own or found a friend to haul.

Neal
first of all 98% of all machinery shipped is via a non union source. The other 2% is via a specialized group. The biggest item in machinery moving is insurance. If you buy a lathe and have it setup you will pay the insurance fee twice, and if you do it on your own you will of course only pay the over the road insurance (it can easilly reach five figures). I know of no domestic unionized machine tool builder, unless it would be Monarch Cortland in New York (they don't make lathes) and I doubt that as well. Brown & Sharpe used to be, but think they are out of the machine tool business. All German pieces of equipment is of union manufacturer, and over half of the Jap stuff is. It's just not a big deal anymore as most all are cost competetive in labor, but engineering is another ball game. Engineering and design are where the money's spent. They may build a half dozen machines before the design is finalized, and in this day an age where half of the equipment is a custom design installation you really start to add the bucks. The one thing the Asians like todo is fill wharehouses with equipment to avoid the buyer having to wait a year or so for delivery. But even that is now considered to be a bad investment. Still 80% of the folks writting a check have absolutly no idea what they are buying. In my job, I usually did a minimum of a dozen onsite inspections to monitor the progress of a particular piece of equipment. Some folks were a waste of time to go up there as it was always done right, and some of them you had to be in there almost daily. The very worst were the small job shops.

The thing I try to impress upon guys I know looking for a lathe (or really most anything) is frame design and construction. Most Asian stuff has a very weak frame design (even the big names). If the frame flexes or changes (they all do) you killed your accuracey. You cannot look at the spindle group and tell if it's a good design or a bad one without the blue prints in hand. But in a used piece you can at least check it for wear (85% of folks don't have a clue what and how). The ways are an over talked about subject, and in the better pieces of equipment there's little difference between a hand scraped bed and a ground one if they are in the same price range. You might try prying up on the lathe chuck with a three foot long 2x4 to see how much spindle movment is in there. Should be less than .001". You can tighten the spindle bearings inside the headstock, and it's really pretty easy to do.

gary
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