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Posted: 11/15/2006 9:00:57 PM EDT
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I've been seeing a lot of posts about machining parts lately. Perhaps it's time for a new forum about machining and part manufacturing. If you can learn to use a computer, as you have if your reading this, you can learn how to use a lathe and milling machine. It's not any more expensive than buying a computer either. A small lathe or milling machine cost about $500. Check out your local tech college or cominity college. They most likely have classes on machining. Just my opinion on the matter. |
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I bought one of the mini-mills from Homier. Homier, Harbor Freight, Grizzly all buy their machines from the same company in China, so they are almost identical. If you google "mini-mill" or "mini-lathe" it would be a start on the information path. Plan on spending almost what you paid for the mill in tools, vises, bits, etc. I did. Scrounge up some scrap metal and try it out. It is fussy and time consuming work, but there are things you can do with your own mill that I wouldn't have believed before I bought it. There is a decent Yahoo group for the mini-mills, with a lot of modification and project info. Quite a few people adding digital readouts, power feeds, and CNC to the baby mills. |
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what about the tolerances of the Chinese machines? what level of accuracy is needed to make reliable parts? I just don't want to spend the money, learn the machine and end up with the "hesse/vulcan home game" setup.  a forum might not be needed just yet, but a tacked thread in "build it yourself" to test the waters would be most welcome. subjects to include: machine selection tool selection (bits and whatnot) materials selection software/ CNC and more, I'm not a machinist yet  Midwinter |
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the cheap machines(especially the cheap combo machines) don't have the greatest tolerances I've ever encountered, but if you are working cautiously and checking things carefully you can pull of any level of precision you'll realistically need for most projects. If absolute rock-steady precision is what you need, it costs more. But it can still be kept quite reasonable by looking at the micro hobby machines if you are intending to do small pieces. You do get what you pay for with machining equipment, but be realistic, most people will never use the full range of a standup rig. |
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When I was in the machine program they had a course in the evening that would come at the end of the day...And there class was 3 hrs... Try Cnczone.com Link |
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This is an interesting and complex topic. I am a mechanical engineer who has experience in cnc machining, solid modeling, cost analysis and tolerencing. I have looked into getting the mini-mills and lathes and have determined that the cost-benefit ratios when machining firearms properly and safely do not come up favorable in the budjet of a moderate shooter. The simple cost of machining a single lower reciever will be well over $1000.00 if you are starting with no tools. If you chose to go the CNC route the price will increase to almost $4000.00 with the cheapest useable tools available. The CNC coding needed to properly complete a lower reciever will take days of coding to properly complete and test. (yes testing with a plastic block will save you time and material cost because the code will not be correct on the first pass (likly not on the 10th either)) and if you do not use CNC equipment the time spent will be just as agrivatingly inefficient (if you give tolerancing it's proper due.) If you do have access to the proper tools without purchasing them then the cost will be lower; you still won't save any money over the purchase of a commercial lower but it will be paperless and your own. So is it worth it? The satisfaction in making something of your own as complex as a firearm is immeasurable. You have the opportunity to make a known design your own and unique such as changing the outer dimensions like the Magpul lower. The knowledge gained may be useful in other fields and endeavors. I personally feel that it is a rewarding hobby and look forward to buying my first home mill, currently I am restricted to spec-ing prototype parts for the company I work for. If you want to do it right, go to school and read real published books on the subjects of interest. Safety is paramount and remember, if you are off by 2 degrees or 0.010 inches in the wrong direction; you just made an expensive paperweight. This is doable and rewarding; but also frustrating and demands a great deal of patience...Good luck. |
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Another thing you need to look at is rigidity. The main problem with junk stuff from China is the total lack of rigidity. If you're going to punch holes and slots in sheet metal it's not that big of a deal, but if you need to mill out the pockets in an AR lower it's suddenly much more important that your mill will remove metal without the cutter pulling it all over the place. You can get a used Haas mill pretty cheap these days. They're useless for machineing steel but they work fine on plastic and aluminum. Of course it's all relative. I'm a machinist, and the two new mills at work cost nearly 3/4 of a million dollars once we got them up and running. About 10-20% of that is tooling. So... If you really want to make things Try this out... Jet makes a really decent lathe (Actually I think they're made in China) but they work well. It's an actuall lathe, not a table-top unit. We have a Lagun (Spanish) mill that's a Bridgeport knockoff but is actually a really nice mill. IMO it's far more rigid than our clapped out Bridgeport. Again, the Lagun is a standalone unit and as such requires space. http://www.lagun.com/products/vertical-mills/ftv1.html http://www.wmhtoolgroup.com/Shop/index.cfm?navPage=5&CID=218 |
Not a machine that I would be willing to bring home. Unless, it is a good used machine that someone needs to "unload" and is willing to sell at a price much lower than it is worth. I don't mean to disuade you from getting your own machineshop set-up, but there are a lot of expensive tools required in addition to the machines. For a suitable used lathe, one is looking at $2000-$4000. For a new machine, double that. A decent vertical mill will cost about the same. To do much machine work, one really needs both. With the combination machines, you will be spending 80% of your machining time just changing configuration, and set-up. Even with separate lathe and mill, often the set-up takes more time than the cut. For a lathe, you will need the following: 4-jaw chuck; Steady rest; Drill chuck for tail-stock; Tool holder (quick change, or turret types are really nice to have); Live center; Dead center; Several High-speed steel lathe bits that you can grind to shape and several carbide tools bits; a pedistal grinder to grind the HSS with one wheel being a green stone to sharpen the carbide (unless you want to invest in a diamond carbide grinder); Test indicater; one-inch travel indicator; set of micrometers (0-1, 1-2, 2-3, and 3-4 inch); 6-inch caliper; Inside micrometer; Small hole gages; Telescoping gages; thread gage (fish-tail); 6-inch flexible steel scale (1/32 - 1/64 on one side, 50ths 100ths on the other. The oprional items are: Collets (need collet adapter); 3-jaw chuck; follower rest (only good for long parts without taper); Spiders (you can make these when you need them); set of larger drills with morse tapers (they go directly into the tailstock and, perhaps, the head stock too); lathe dogs; Face plate; There are others, but I'm not sure on their usefulness. You are looking at a similar number of fixtures and tools for the mill as well. When I priced a fully equiped personal machineshop a few years ago (one for my personal gunsmithing needs and other stuff), I estimated that I would need to spend about $25,000 to $40,000; I have all my measuring tools and hand tools so these are not included in the the estimate. Dave. |
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You could also look in this thread for more information www.ar15.com/forums/topic.html?b=1&f=5&t=517553 |
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Those table top mills and lathes from China will work if you know the limitations. Since the machines are so light, heavy cuts are out of the question. Try to make all cuts in one direction to eliminate backlash complications. Large machines like Bridgeports all have backlash but it's easily corrected with a DRO setup. Would be a waste of money to put a DRO on the small machines. I used to make car parts with a $200 lathe that was made in the early 1900s because that was what I could afford. If you use a little brains, it's easy to make do with what you have; no need for a $4-5k machine. Check out the scratch build AR build thread and you'll see what can be done with a small mill and some clever ideas. www.geocities.com/elmgrove1765/project6/project6.html |
Is that your web page? |
| These small machines would be good for small parts like sling adapters, an attempt at handgaurds or something along those lines. Ive been machining for about 5 years now and work in a pretty high speed shop and I wouldnt eevn attempt a lower reciever or anything like that. Alot of skill and precision goes into these rifles, and trust me after you've done this type of work for a while it might be cheaper to do it yourself but it is always less frustrating to have someone else do it. Props on the lower reciever, looks pretty good. |
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You could always go to the Roderus forums: www.roderuscustom.tzo.com/ |
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Anyone have any experience with the Smithy mills? Smithy I wonder whether $ for $ they're better than the Grizzly/Jet/Harbor Freight mills. Here's an interesting small mill site: www.mini-lathe.com/Mini_mill/Versions/versions.htm |
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You allready have a forum for this. You posted in it. "Build It Yourself".. Bout damn time someone starts building something in here. All I have seen so far is everyone playing with Legos.. Seriously though, just post here.. Check at CNCgunsmithing for some of his neat projects. |
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| surprised no one mentioned this site yet www.cncgunsmithing.com/ |
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IMO, don't waste your money. A buddy of mine got setup to machine his own .50 cal. recievers. He spent $30,000 on a Haas VF-2 which is a pretty good price. My boss has a Brother TC-217 we'd probably unload for around $25k or so. This is a really expensive business. Just think, You're going to spend $170 on a good dial indicator. Interapid is the only one we'll use. |
Very nice.....Manual mill? Is that a Jet? Before and after looks like a new gun! Very nice work... Paul |
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Hi Blammo, It is not so much as not a lack of a machining forum here to me, it is just that I go to homegunsmith.com for machining topics. I use arfcom for inspiration, and go there for machining and gunsmithing. Those guys tools vary from files and hammers to CNC. It is also a different mentality. The guys here seem to be parts assemblers with thousand dollar gun budgets, and problem solvers there. Ill finish that 357 maximum rimless sooner than later and post about it. Its been a couple years with not much spare time. |
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Paul, the mill is a Grizzly. There's a link to it in my post with the picture of the mill on page 1. I don't have a power feed or DRO, so it's 100% manual. I used to think I'd never make it far without a DRO, but as I got more comfortable with the machine, I found I could confidently make a cut with near perfect accuracy. If anything, I'd love to have a power drawbar and a variable speed motor, but that's not happening any time soon. Pogo, I agree -- www.homegunsmith.com/cgi-bin/ib3/ikonboard.cgi is a great place for real build-it-yourself info. Great group of guys there too. Maybe we need a thread here to show off homemade parts and home-machined projects. |
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