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split63
04-07-2006, 03:48 PM
I'm looking to buy a verticle Mill, I'm not in a hurry so I'll wait for the right one to come along. But where to start?

I have used the big Knee Bridgeports and certainly they can do the job, though it may be a tad big. In general this is what I would want to see in a mill:

Power feeds all directions
230V Single or three phase
X,Y,Z digital position read-out.
Solid - Heavy
Variable Speed
Accurate, stays true
Supports or includes oil mister
one shot oiler/luber

I will buy used. It would be fantastic if it had Optional or standard computer control of some kind.

I also wonder if perhaps I should just forget this mill and shoot for a small CNC Mill. If there was a good quality, not-obsolete unit that makes sense for the home shop, then I would tend to lean this way. But I have no experience with these and I don't know what key things to look for.

Recommendations? ;)

thistle
04-07-2006, 04:12 PM
No need to be scared of 3 phase ,a VFD on the machine will cure the problem
of single to 3 phase , with some advantages.

my 2 cents

split63
04-07-2006, 04:26 PM
No need to be scared of 3 phase ,a VFD on the machine will cure the problem
of single to 3 phase , with some advantages.

my 2 cents
Hmmm, I had heard that these were available, but I jumped to the conclusion that they were horribly expensive. I did a quick search, and while they are expensive, they are not too bad.
http://www.driveswarehouse.com/Drives/AC+Drives/Gen.Purpose+Drive/L100-015NFU.html

So perhaps hanging on to my request for single phase 220V is not important.

Thanks

Tinkerer
04-07-2006, 04:44 PM
Was wondering what effect does running a 3 phase motor thru a inverter or VFD have on your monthly power bill. Anyone that added a machine care to share your veiw on this.

Thanks

3 Phase Lightbulb
04-07-2006, 06:05 PM
I run a 6HP 3-Phase rotary generator in my shop for both my 2HP 3PH Bridgeport, and my 3HP 3PH lathe and I never noticed a difference in the electric bill, but I only run my rotary generator when I need to use my machines. I'd say I probably run it about 10-12 hours a month (2-3 hours per weekend, if that). I think I pay around $.20 or $.30 per K/watt hour. It probably costs me around $.50 per hour or so..

-Adrian

IOWOLF
04-07-2006, 06:17 PM
Don't forget a one shot oiler/luber.

gsp
04-07-2006, 10:36 PM
I have a Sharp 13x40 lathe, 5hp vfd on a 3hp 3phase motor. I was playing with it quite a bit when it was new. Electric co. called my wife and said are usage was up 30%. I dont play as much so I would say 15% as average.

Tim

lane
04-07-2006, 10:54 PM
Buy a Birmingham,BP type vertical mill about 4500.00 with dro an power feed Stadic phase conveter 158.00 3to5 hp model .

IOWOLF
04-08-2006, 08:35 AM
Buy a Birmingham,BP type vertical mill about 4500.00 with dro an power feed Stadic phase conveter 158.00 3to5 hp model .

Stay away from static phase converters, Go 220 single phase or RPC.:(

SPC"s cut power by a third.

rockrat
04-08-2006, 09:42 AM
I hope that I'm not asking the obvious, I might have missed something here.

Before we answer your question, what type of work will you be doing?
How big do you foresee the parts being?
Will you be working mostly aluminum or a mix of materials?

This might get you off the hook - your allowed to answer "a bit of everything". Which is what many of us do. But an answer like that will not help you narrow down the possibilities.

Many of the machines that I have purchased were good deals. The Van Norman milling machine was saved from the scrap man. And it was therefore a cheap purchase. So, I cant really say I had plans for it, but I just could not pass it up.

My lathe, It had to have 2" min through the spindle. I wanted to be able to cut threads, tapers and I wanted a foot brake. That narrowed it down for me as I looked around. And it kept me from chasing a lead that may not have paid off.

So, items to think about (others chime in if I miss something)-

Power- I wonder if this wire is hot. Zzzzzzzit, ouch, I guess it is.
I would agree with thistle on 3 phase power. In fact, at auctions I have seen items passed up due to the machine being 3 pase. Or, being sold cheap because the buyer is planning to swap the motor out for a single phase. If this happens while your around, offer the buyer a few bucks for the working motor. They may even give it to you. It might make a nice little RPC. Speaking of RPC's...

RPC, VFD, SPC - Decisions decisions decisions..... I use a RPC. It was cheap to put together and works fantastic. I know gents that use the other two types as well and they both like them for different reasons. Best bet, do some reading on how you want to convert the power if you have to. BUT, just know that you can use a 3p machine if you want. I would suggest, staying in the 220V range with the machine under 3p power unless you want to make a motor swap. There are machines that are 3phase 440v and would need a step up transformer plus enough KVA to feed it. A member or two here have done this but it was a bit of extra work in my opinion.

Transportation - It aint that big, I think I can carry it. Pop! Was that my back? Can you pick that vertebrae up for me, I might need it later. :D
How will you be moving it to your humble shop? The Van Norman was every bit of 3,000 lbs. You dont just grab this thing and drop it in the trunk. Many here have rented trailers and forklifts. Yours truly has borrowed a trailer and used pipe and a come-along to move a machine or two. Some here have them delivered by a rigger and set up. One fellow had to have a crane drop... oh, bad choice of words, place his machine in his backyard via lifting it over his house. How do you make a choice here? Well, your location, friends, wallet, drive and your back all are factors. Something to think about.

Tooling - I see R8 collets... there everywhere.
R8 is very popular. Its hard to be at a tooling auction and not trip over R8 collets. The word popular just does not fit the R8, its almost given away (I jest, I've never had a collet given to me... yet).

But, what tooling is needed for that creampuff of a machine your looking at? Yup, your getting a good deal now, but if the tooling holders are a funny size, you might be using all of your leftover money to buy just a few collets to try it out. I have a mill that takes NMTB 30 taper tooling. This would be a big deal but, I was given a box of the stuff with the machine. The VN takes a VN type collet. Again, I was given 2 boxes of tooling with it. Then I made an adapter to get the 30 taper stuff into the VN. But you may not want to make adapters to use your mill.

Repairs - It aint that bad. I can fix it... Maybe... I think... Aw, just go buy another and toss this one out.
If your thinking about buying used, there are a few more things to think about. Had a buddy of mine buy a lathe. He asked me if I would help fix something on it. I agreed to help out. I thought that maybe it had a broken tool holder or a busted steady rest or something like that. No, the headstock was nearly split in two and a piece was missing. Looked like someone had dropped it while it was upside down. I didnt have the heart to ask what he paid for it.

But, search a bit on here and look for past posts on items to look for when buying a machine. A few hours of reading will save you major headaches down the road.

CNC - Can you cut this purty hoochie-ma'bobber for me on your cnc? I want to make my gun full auto with it.
Ok, cnc adds a bit of thought to the question of purchase. Can you easily add CNC to the mill? How computer / electronic handy are you? Do you just buy a CNC machine and go, forgetting about a conversion?

Personally I love to program cnc but at times I just want to cut metal. So its nice to have a mill that swings both ways, if you know what I mean. (wink wink, nudge nudge, say no more, say no more) If you buy a CNC, try to get one that will take a rs232 or better cable for communication. Or, consider one with a pc built in. I bought a cnc that took tape and while I can make parts, it ends up being more of a novelty / pain than its worth. But, I'm happy when I think about how much I paid for it. It works for me.

But, if your not comfortable with the computer (you wouldnt be posting here would you?) you may want to get a package that is all ready to go. That is to say, a pre-packaged CNC system, bolt on and run. That way, you can mount the encoders (you do want encoders dont you?) and with a short call to tech support (or not), be up and running. Look at the options for those packages now, before you purchase a machine to convert. Email the companies and make sure that the package will run on what your thinking of buying. Some of the old hydraulic cnc mills may not take a cnc conversion easily.

Others here (IBEW and the like) have built / converted their own CNC mills. Took them a while but they have running machines. And the information that they learned while doing it has made them better as well as spilled over into this little bbs. The rest of us lap it up like puppies.

Congrats, you have reached the end of my drivel.
There may very well be other items for you to consider. The aforementioned are the ones I think about when I go looking about. And dont let it all scare you. Many of us have bought stuff and later scratched out heads wondering what we were thinking. Come here and ask questions. We will be more than happy to see you with some fine iron and making chips.


rock-
as he edits again... "A spell checker, a spell checker, my kingdom for a spell checker!" sigh....

thistle
04-08-2006, 12:21 PM
I have a big RPC for my big stuff , but am putting on VFDs for the small motors so i dont have to fire it up all the time.

the big RPC makes the meter go round.

I also have a single phase mill, and to be honest I dont like the single
phase - just becuz-

If i was feeling like tossing away some money i would actually convert it to 3 phase.

here is a link to the PM site and an article by Forrest Addy


http://www.practicalmachinist.com/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=3;t=000002;p=0

split63
04-08-2006, 12:34 PM
Wow, now thats some reply. I think I reached my reading quota....for the month. :)

I have considered the issues you brought up....but I don't have enough experience with them to know what to look for in many cases.

My goal of the post was to narrow down the field to a particular manufacter and unit, or at least a small set. That way I can try to come up to speed on them so that I can know what to look for.

It sounds like the Bridgeports are a safe bet. I generally just reject the Chineese/Tawainesse made units right from the start. For quality, reliability, and patriotic reasons. I want to go with a unit for which parts and accessories are widely available and therefore less expensive.