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Milling machine consideration questions.

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  • #16
    Is a CNC milling machine, like I posted earlier, more likely to have seen heavy use and abuse? I was wondering if people program their cuts to take the maximum material per pass that the machine is capable of, or if the programmed cutting produces relatively uniform forces on the tool. If I were looking at a tool that is "used up" where would the wear and tear be most apparent? Would it be in the servos, the bearings, or the ways? How robust are the machines when used with the CNC capacity in a production shop.


    • #17
      SJ.. My machine came from a plastic mold and die shop. It was made in 1976. checking with indicators The worst axis was the Z (up dn) and it was .0003.. I kinda blame that on a loose gilmer belt now thou. Repeatability is what I was checking for. No clue tho how to check them other than dial indicators., check the table it gives a good indication how the machine was used or abused.. ANy marks on the table tells a tale.
      I love the ball screws.


      • #18
        I think I could live with that (.0003) I am afraid of getting a machine that was in continuous use by unskilled labor. I don't think any machine can put up with that for very long.


        • #19
          I think you put your fingers on what is required to get the mill you want... The big problems are shipping, and putting it where you want it on a budget...

          If you have an idea of what you really want, then its OK to spend some money. Getting something less than you want or not what you want is not saving any money.

          First, is there a metal working club or group in your area? if there is, talk to the members. People looney (Yes.. looney) enough to stick big Bridgeports, lathes, CNC turning centers, ingjection molders, welders and such in the garage/workshop are definiely not in the majority out there...

          Bikers have been puttting up with this kind of crap from the general public for years now.. So you can look at them and see how they have to network and "stick together".

          That is the second group to get in contact with. Custom bike makers.. Anyone who knows how to make a georgeous gas tank with an English Wheel will know ALL KINDS OF THINGS... Network..!!!! Bike makers have to network to get things done, too. Bike makers turning AL billets likely have a BP in the garage already... so what did they do to get it there?

          Third group to check out are riggers and those who support aircraft repair.. Likely they have to network, too. Sometimes they are sources of who has "2 CNC mills for $500, with rotary tables" in perfect shape. Does happen. Happened in Phoenix last week... You have to ask around, network with the local metal guys... Riggers can tell you who might be good choices to work with for transport and shipping. You might find the perfect mill in Wisconsin - a CNC Series II with True Trace attachement - perfect condition... but if you can't transport the unit, you are busted.

          So there is a budget for rigging (on and off the truck) and shipping - to where you are..

          To watch out for... Home Owners associations.. Some of them will try to evict you if you park your car on the grass or pick your nose in public. Fertile recruiting ground for neo-nazis, that is for sure. Check the local regs out before buying a machine.

          I just went through a lot of this, so suggestions are based on my very limited (some excellent - some not) experience. The most important thing is to network. It is also the only way to keep sane AFTER you get *the big mill* and you have to keep it running.

          The Egyptians moved big blocks up big inclines a long time ago. A block and tackle or the right pry bars will get it where you want it. It is all a trade off of time and resources.



          • #20
            (okay enough ribbing ,poke poke.. ha ha)

            I'd definitely talk to people,. Yes there are series two machines out there, but what do they weigh? It takes a semi to move one. I looked at one in Chicago that was less than a grand, but the 5 ton rental truck was too small. I calculated it over 8,000 pounds.
            Tooling is a big consideration too. What do they have with the machine, what does new tooling cost. I bought a cnc machine with kwik switch spindle. Purchasing end mill holders and mills has cost as much as the machine.

            I think marks on a table of any kind show unskilled labor at work. Does that make the machine junk? well it made me look at it harder.

            I wanted a bridgeport so bad, I sold my harley to get one, I didn't buy the first one I saw. It takes some sacrifice to get what you want in this world. When I got it home, I gutted it like a fish. My girlfriend came in and saw the stuff I had pulled out of my new aqquisition and nearly fainted. She asked why I didn't just buy one already converted. I told her they cost ten times more and I could not afford one.

            Anyways guys, go for what you want. A small machine does small work. Casting dies is what I wanted one for. Casting outfit is just about done. Now I got a new learning curve on the dies, but I got the machine to do it. Hopefully someone here has some experience for me to pick thier head.

            what I am trying to say is.. if you got room and can afford it, get what works for you. each tool is designed and sized for a type job. I started with a Unimat, found out it was only good for real small things. It would not turn a 3/4 bar into a axle in my lifetime.
            My next toy was a mill-drill-lathe and another heartbreak. I personally don't have the paitience to work with one of them. When a chuck stops dead in it's tracks with a 1/8" drill it is too weak. It was from HF. I am unsure about the other makes, but I would have to try one out now before I bought.
            It is bad enough learning on your own, but is it the machine or me?

            I have saw bargains on ebay, but, coon dogs and land are only worth what someone will pay.
            A real good thing to do is watch the auctions purchased by a (0) feedback and write the seller. Usually they don't pay up on big ticket items. I keep seeing the same shaper on ebay.. over and over..

            Dvideo, I got a english wheel, mine converts into all kinds of toys, it ate up space before that and was nearly useless in a small shop.


            • #21

              I guess you fit the requirements of someone to ask, then.... One of the real big problems is that someone new to machining, unless they are in the business, will get the feeling that they are pretty alone. And it's true.... May be not in Chattanooga, it has a rich history, but go to Denver, Dallas, or Spokane. IF you are in those places, you have to get up and go actively looking for people to network with and that know what they are doing.

              I did not really intend to paint your picture, but but guess I did. I was thinking like I always do in computer design... "What about the person in Alice Springs? Or Hobart? Glasgow? London? or Sacremento?" What is the best thing for them to come up to speed with? - chances are talking with an Aircraft Mechanic, Rigger, Bike Builder, and the like is a good start... People don't think to ask sometimes.

              As far as bilding pyramids... Well after casting, have you considered stone work?

              I am unaware of anyone else in my home town with a garage shop having big mills, lathes, and the like... they are probably there, but I don't know of them yet. I have to camp out on the Web and look at profiles.



              • #22
                pyramids they say were built long before the egyptians came into power. (newest talk)

                Stone work, I suck at it. I can't get the mud right, a simple thing for other people.

                I was tickled to find this site with people like Thrud, SJ, Wierd, Ga. and others to pick thier brains.

                I just hope I can give a little back.


                • #23
                  Tattoo'd Gorilla

                  Ya sold the Harley? Man, you REALLY wanted that mill - bet it leaks less, eh!

                  I was going to ask you if you tried carbide endmills with the D-2. If you have not, do so. It should cut well with the carbide and .oo3-.oo6" fpt. And don't bother trying to anneal it yourself - it is just tough to begin with. I would either keep it for cutting tools (broaches), construction of precison instruments, mandrels (cold working), etc.

                  The best stuff for the HOT Light metal injection dies is H11 or H13. H11 can be used up to 1000* an H13 to 1300* - Ideal for Aluminum. Be warned it is very tough to cut as well - carbide is best for these. The H & D series should be considered "air hardening" and best done in a controlled HT oven.