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How crucial is work envelope for smaller VMCs?

ions82

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Nov 1, 2006
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ABQ, NM
I have been keeping an eye open for small VMCs to see what is floating around the market. This is something that will have to fit under my garage door, and I am currently limited to a 50-amp breaker. So, the machines I've been looking at have been 10HP and under. In the past, I've read a number of posts in which people wish they had gotten a machine with bigger travels. Is this a problem that is often encountered? I will mainly be making small parts out of aluminum. The biggest part I plan to make is around 10 x 2.5 x .75. I have no desire to try and do big production runs or grow into a competitive job shop. Part of me thinks that a small machine would help prevent me from becoming too "ambitious" (always looking for bigger/better).

Anyway, I guess I'm just wondering how small is TOO small. Would a 30-taper machine with 12-X, 10-Y, and 12-Z only be good for the smallest of parts? The pieces that I'm currently making manually are a little over 2.5" long. Most parts that I forsee myself making are no more than 4" in length. I like the idea of a small machine that doesn't take up much space and won't require me to get a new 200-amp service drop, but I also don't want to end up cornering myself with a machine that limits my capabilities. I know that things like box ways and 20HP spindles are great for removing material in a hurry, but I have no plans to set records for material removal. I've been seeing some Kitamura machines that look rather appealing. Has anyone in a similar situation found that a small VMC quickly turned into a significant limitation?
 
It's a very subjective thing and you have to realistically apply it to the type of work you're doing. For instance mine is a 40x20 and it seems like every day I have a job that makes me wish I had an extra inch in one direction or another. I think the best thing you can do is commit to a work envelope to suit the job at hand. There will always be jobs that are too big no matter what size your machine. That said I would think twice about the 30 taper unless you're only ever going to use tiny tools.
 
I would definetly go for at least the 40 taper, if you can. Make sure the machine you get is capable of storing the programs you will use. My machines are fairly compact, but they get the job done.

BL
 
I'm with Gregor on size of work envelope being subjective. If you don't see yourself doing anything much more than 4" then something like the Kitamura would probably work great. I have 4 Matsuura 500 mills with 20 x 12 x16 travels. Sometimes I wish they were a little bigger but for the type of work I do this fits very well 98% of the time. You can find these fairly reasonable also. They don't have all the bells and whistles of some of the newer machines but work well for my applications.
Michael
 
Do not get anything smaller than CAT40 in the spindle or you will have a difficult time getting tooling.

Make sure the machine has a table several inches bigger than the travels and that the enclosure is again many inches bigger than the table. It is possible to work on things bigger than the travels if you can clamp it and it doesn't bump into the enclosure.
 
Get a Haas MiniMill with 4th axis. Fits inside the garage, runs on 220V 1ph. Will do whatever you can get into it.

Tim in D
 
It seems that 40-taper is the way to go. The only reason I considered a 30-taper (or even the 35 in many of the Kitamuras I've seen) is because I don't plan on doing much other than small parts in aluminum. There aren't many 40-taper machines that will fit into a garage (and use less than 50 amps). I was under the impression that 30-taper tooling isn't hard to find but more that it can be lacking in rigidity and heft.

Anyway, I will continue to look around at VMCs that are at the smaller end of the spectrum. I've seen a couple Fadals that have a 40-taper that MIGHT be able to slide into the garage. Other than those, the only others I know of are the Haas Mini or Sharp SV-2412, and those have been discussed plenty. For 30/35-taper spindles, there are some nice Kitamuras, Robodrills, and Brothers floating around. They all make me drool. If I buy something, I want to make sure I won't be kicking myself for getting a bigger/heavier machine (as the prices don't seem to be much different between them). Thank you for the insight and taking time to reply to my post!
 
The Haas MiniMill with a 4th axis is a bit constricted, the Z travel is only 10"; the HRT160 will fit but it severely restricts the useful Z travel.

I think a really good choice is a Super MiniMill with the 4" Z extension and the HRT210 but you do lose the advantage of running on single phase and the cost is much higher.
 
30 taper machines aren't popular around here, but I own one and I'm quite pleased with it. Think about the largest diameter cutter you typically use and use that to help decide whether you need 40 taper. I only use larger cutters when I'm making a fixture, so the limited rigidity of the 30 taper is of little consequence.

I've found 30 taper tooling cheap and easy to find on ebay. Sometimes I'll have to wait for the right tool holder to pop up on ebay, but I haven't needed anything I couldn't find. I'm not a job shop needing exotic toolholders, and I usually dont' need to have it 'yesterday.' 35 taper tooling is much less common than 30 taper, and also less sought after, so prices are also low.

Robodrills are cheap now, and quite reliable with direct drive spindles and simple, fully mechanical tool changers. It only uses air for the spindle blow, so it doesn't require much in terms of CFM, and it doesn't drop tools if there is a loss of air pressure. Even the old ones are fast (in terms of rapids, spindle start/stop, tapping, tool changing) as garage machines go. Support is excellent through Methods Machine Tools.

For all the people who voice regret for buying a small machine, I reckon there are a whole lot of folks happily (and quietly) running their smaller machines, including me. My only wish is for more spindle RPM. 8K gets the job done, but 10 or 15k would be better for the small cutters I use.

QB
 
Ion, a couple of things to keep in mind, although your parts may be say 10" in length, typically you'll want to make a fixture to hold them, so add at least 2" on for that. Then to be able to machine both ends of that fixure, add 2 x times the tool diameter, so add another inch. So your 10" part needs 13" to 14" of travel.

The other advantage of extra travel is to be able to make a pallet for your parts (fixture that holds multiple parts). Even if your runs are small this can be a real time saver as one button push gets multiple parts made.

If you're not sure about what size parts you will be building in the future, I'd get the biggest machine you can afford and fit in your garage. You'll get the widest selection of tooling with Cat40, but the 30 size is also pretty available, although in the US the BT30 size is the more popular size while in the 40 size Cat40 is more popular here.

Some manufactures don't recommend it, but many have used rotary phase converters to generate 3 phase for smaller CNC machines, as trying to stick to single phase machines is going to limit your selections. A cleaner (and quieter) way to go would be to use one of the solid state based phase converters.

Frank at www.maritool.com, who often posts on this forum, sells the BT30 and lots of other good quality tool holder for good prices and gives great support both before and after the sale. One thing he has pointed out about BT30 tooling is that the increases in both spindle and table speed of the BT30 machines is starting to push the limits of the pull studs on those machines, so keep that in mind if you end up with a BT30 machine, keep a close eye on the pull studs.

Good luck-

Paul T.
 
...he has pointed out about BT30 tooling is that the increases in both spindle and table speed of the BT30 machines is starting to push the limits of the pull studs on those machines, so keep that in mind if you end up with a BT30 machine, keep a close eye on the pull studs...

This statement seems a bit alarmist. I'm sure the newest machines may be capable of pushing the limit of a 30 taper pull stud, but I get the feeling the OP isn't looking for 20k spindle, and he said he's not trying to set MMR records. For the stated needs, pull stud size isn't going to be a factor.

QB
 
Thanks again for all the input. I don't forsee myself needing to run end mills larger than .500". So, I would think that a 30-taper machine would suffice. If a small VMC would handle 98% of the work I will do, I wouldn't think that the extra 2% would be worth the space, money, and power needed by a bigger machine. I imagine the bigger motor(s) of a heavier machine would consume more energy over time. However, that may end up being a negligible difference. The space and initial cost would probably be a much bigger factor.
 
Ions, your original post sounds just like what I was thinking some years back as far as machine requirements. I ended up with a little VMC that has 14"X and 12"Y and 14"Z with 8k RPM and cat 40. I make a lot of small qty close tolerance parts. Even still, the machine is always just a little too small.

As mentioned, there will always be jobs that are just a bit too big, no matter what machine size you have, but with a machine the size you are speaking of and that I have, it's just always too small it seems. You are constantly out of room on the table for clamps and two vises. A vise and a fixture, or a vise and an angle plate, all get to be a big pain. 6" vises can hit the column in Y if I'm not careful. The toolchanger is so close that when I plow with a 2" facemill it's bouncing chips into it and even out the top of the machine.

If I have a vise on the table with a taller part in it, a long drill in the toolchanger will hit it when it changes tools. I've turned away lots of work that was 18" long. Spent time moving parts around in vises to get the whole thing

Looking back, having a machine with 20" in X travel would be much more ideal. The door would be bigger and easier to setup and load/unload and just less frustrating on a daily basis. My little machine has paid for itself and has been good to me, but I recently bought a 40" machine and find it much nicer to run all in all.
 
To the O.P.

Go with what you think is enough. Since you are the boss, you should not have the problem us employees have. The boss always thinking that the machine will have infinite travel/capacity just because he would like it to.

Jeff
 
Is there a minimum travel that could facilitate two 6-inch vises? I suppose a lot of the parts I plan to make could easily go into a 4-inch vise, but it would be nice to be able to use a pair of 6-inchers if the need arose. As I said, I have no intentions of trying to grow into a competitive production/job shop, so this may not even be something I should worry about.
 
I have a pair of 6 inch Kurt vises installed on 9.5" centers in a Haas SuperMiniMill with a HRT210 on an outrigger plate to the right of them.
 

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You can always run small parts on a big machine. The transverse is not always quite so simple. Get the biggest you can.
 
Get the biggest you can. You may only run small parts, but when someone needs lots and lots of those little parts a bigger table and travel will let you setup more vises and fixtures. I have a pair of 2412's and I run parts mostly in 6" kurt vises, one or two vise at a time per machine. It's nice to have one setup in the left vise and another in the right, offsets programmed, etc. Anything smaller and I wouldn't be very happy. I tried 3 vises once because they do physically fit, but they slow down the rapid table travel and I was overall uncomfortable with it. In a bigger machine you just have alot more flexibility.
 








 
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