[moldmker]

This has probably been discussed before but a search didn't reveal much.

A local shop is selling their 2001 Mini Mill. They have 2, one seems to stay busy with a dedicated product line, the other sits empty.

Every time I go over the work envelope #s, the 10" Z travel looks very confining. I currently have a larger VMC.

Are you guys using 6" Kurt vises in these?
How about extended toolholders or drill chucks?
I think the spindle is 7.5 hp, has anyone had any rigidity issues?

One job that I run alot of entails pocketing aluminum blocks with .5" rougher x .62" deep, 4000 RPM, 30 IPM, lots of coolant to clear the chips.
Would this be OK on a Mini Mill?

Thanks,
Bob

[Geof]

...Every time I go over the work envelope #s, the 10" Z travel looks very confining. I currently have a larger VMC.

Are you guys using 6" Kurt vises in these?
How about extended toolholders or drill chucks?
I think the spindle is 7.5 hp, has anyone had any rigidity issues?

One job that I run alot of entails pocketing aluminum blocks with .5" rougher x .62" deep, 4000 RPM, 30 IPM, lots of coolant to clear the chips.
Would this be OK on a Mini Mill?

Thanks,
Bob

Yes the 10" is a bit confining. We use 6" Kurt vises but our parts do not stick up much above the vise. Drill chucks are out, they are too long. Lyndex ER holders are even a bit long and stubby drills are a good idea. Rigidity is okay but the 600 rpm max and 7.5 hp is a bit limiting. It is possible you could run that rough okay on a MiniMill because your speed and feed is conservative.

What a\price is b eing asked for the Mini? If you can get it for $15,000 I think it could be worth it; if they are asking over $20,000 they are breathing thin air.

[Donkey Hotey]

Last year, I seem to remember a debate about the value of a Mini vs other machines. Geof really likes them. I think the gist of the conversation went like this:

If it's going to be your only machine, it's not such a good choice. If it's going to be setup to run one type of parts, it's a great value. It takes up little space and while it might not be the most rigid or fastest machine in your shop, it will free up your other machine while it slugs out your production stuff.

It sounds like you already have one job that you know will fit in the envelope. You can purchase specific cutters for that job and might even invest in a custom tooling plate to hold more parts than a pair of vises. Now you can set up the job, press the green button, then work on something else while it prints money for you. That's a lot of bang for the small bucks and footprint.

[automizer]

I sit in front of a mini mill and super mini mill all day and there great machines.
If you can pack in the part you want to do try putting it in the machine and see how it fits.
they are good at hogging out Alum. but you need to watch the bottom and keep the chips out. I have had coolant run down the handle of the chip scraper on to the floor. The bottom fills up preaty fast if your hogging and there isn't much room so that is my biggest beef with this machine

[billystein]

Hi,
I have the 4" extended z. still has 10 inches but 4" clearance. my problem is that with small cutters I have been forced to buy 4" end mill holders just to reach the top of a vise.
i don't think that a 1/8 em will touch the table with a 4 " holder.


billy

[Geof]

Hi,
I have the 4" extended z. still has 10 inches but 4" clearance...

.... i don't think that a 1/8 em will touch the table with a 4 " holder.


billy

I think that is an advantage; I don't want to touch the table with any end mill.

Seriously though the 4" extension sometimes makes it difficult to go far enough down, but it makes it possible to mount the HRT210 rotary and have rotary fixtures that cover the entire X travel and machine parts sticking 4" out from the A axis.

[mactec54]

Hi Moldmaker
The Zaxes has 14" of travel the 10" is the tool change height so you have 4'' it can go up after a tool change if you need it to clear any thing & the height is fine with Kurt vises if your tool holders are the shortest you can buy then you have plenty of room for most jobs

[Geof]

I seem to remember reading somewhere in Haas literature that using the 4" above Z zero is not recommended because the guides are not fully anchored up there.

[moldmker]

Guys,

Thanks for all the good info.

Geof, your pricing is right in the ballpark of what they're asking. (options: rigid tap, coolant tank, 3.5" fdd)

I'll post the outcome of the deal next week.

Thanks,
moldmker

[mactec54]

Hi Geof
You need to check with Haas Tec support because they told me that it is not known by many because knowbody asks about the extra 4" of Z travel but they told me that the extra 4" was there to use Management also backed this up as well

Those that added the 4'' to the Zaxes don't have as ridge machine by doing this

There is plenty of room if you buy the right tooling 2 photos attched the part is 3.5" above the Kurt Vise the tool/End mill is 3.6" out of the tool holder the first photo the tool is at 4" above the part the second photo is with the Zaxes 8" above the part I would say you would have to have a very large part to be a problem on this machine & then you can mount the part on the table or buy a bigger machine

I also have the same rotory table size as you do & it is not a problem I have even lifted the rotory table up with a 1.250" spacer to swing a bigger diameter with still no problem with tool clearance

[Geof]

....I also have the same rotory table size as you do & it is not a problem I have even lifted the rotory table up with a 1.250" spacer to swing a bigger diameter with still no problem with tool clearance

Show me a picture.

[Geof]

Here is what I posted above;

I seem to remember reading somewhere in Haas literature that using the 4" above Z zero is not recommended because the guides are not fully anchored up there.

Sure looks to me like the Z axis guides are not attached up at the top of the travel. Of course I am getting old and my eyesight may be failing.

[mactec54]

Hi Geof

When I have that job & setup again I will send you the photos

The Zaxes linear bearings do not go all the way to the top as that is were the Home/ limit switch is mounted the bottom of the linear bearing is still supported by the rail which is still attached to the Zaxes cast column/frame & You then have with the Zaxes all the way up 18" from the table to the nose of the spindle so you can have a 14" part mounted on the table a 2" tool & have 1.750 tool clearance .250 so you don't hit the stop & you still would have the linear bearing with full support when you were cutting

[Geof]

.....& you still would have the linear bearing with full support when you were cutting

How? the upper bearing truck is above the top of the casting? I am not saying your measurements do not add up, I am saying that you stand to lose some rigidity, maybe more rigidity than you lose by getting the 4" Z lift. In addition you lose several inches of X travel because you need to move the work piece to one side for the shuttle to come in and the spindle to move down for a tool change. As I pointed out above getting the Z lift allows permits utilization of the entire X travel.

[mactec54]

Hi Geof
If you Have large parts you have in your program you move the X axes to the right to move your part before a tool change the side tool changer took care of this problem

With your 4" lift you lose approximate 1/3 that of the normal Machines ridigity I know you can do the math on this if you do you will see that 1/3 that of a normal machine without the 4'' lift is close

The linear rail is bolted at the top of the column so when cutting the upper linear Bearing would have full support when cutting as the upper bearing truck would not be past this point on the fully supported rail the upper unsupported part of the rail gives you more room to move your tool around to clear your parts so no lost ridigity when cutting

You are right about the shuttle/carousel that is the only advantage for the 4" lift & if you use a 4th axes all the time

The side mount tool changer can take care of this as well & you will still retain the normal machine ridigity with out the lift or you could buy the new TM2 & don't forget the sidemount tool changer This machine is a much beefier machine than the TM1 & will be my next buy

[Geof]

....With your 4" lift you lose approximate 1/3 that of the normal Machines ridigity I know you can do the math on this if you do you will see that 1/3 that of a normal machine without the 4'' lift is close...

Are you doing a simple beam calculation here; standard length L cubed and divided by L + 4 all cubed to get the proportional increase in deflection at the same load? I think it is dependent on length to the third power.

This calculation, in and of itself, may be accurate; although it is not a simple beam and the 4" spacer has a different cross section to the main part of the column, so it probably over estimates the loss of rigidity; also it is only relevant if column flex is the major source of movement. Tool deflection at the cutting tip is a summation of tool holder and spindle flex, spindle bearing clearance, and what I think is probably the largest source, the Z axis linear bearing clearance and the lever arm distance from the Z ways out to the spindle centerline. All these are not affected by the spacer and it would not surprise me if they summed to a much great amount than the column flex; a 1/3 increase in a deflection which contributes only a small amount of the total is not a 1/3 increase overall. I have Supers with the standar Z axis and with the 4" spacer and have not seen any obvious differences in identical parts done on the different machines.

[slatern44]

Geof or Automizer,
Since both of you have mini's and super mini's I was wondering how big of difference do you see on a cycle time between the two machine with the same program? I know there are lots of variables that can be different but just say its a 8 tool job with a 10 minute cycle on the mini and they you go put in on the super mini is it much shorter? because now you have faster rapids and faster tool changer. I have two mini and am looking at getting a super for the higher rpm spindle.
Thanks.

[Geof]

Geof or Automizer,
Since both of you have mini's and super mini's I was wondering how big of difference do you see on a cycle time between the two machine with the same program?......Thanks.

I did make a note of this a few years back. It depends on how many tool changes you do and whether you are removing a lot of material at high rpm; I think in some cases it was less than half the time on the Super.

The tool change time is about half, maybe less on the Super, and a cut that the Super will handle in aluminum at 10000rpm and a feed of 100ipm on the Mini it may have to be slowed down to 30ipm at something like 4500rpm. I have found the Mini can be induced to remove metal faster sometimes by running below maximum rpm because at 6000rpm the torque is SFA.

An indication of my preference might be that I bought two Minis back in 2001 a Super in 2002 and my fifth Super will be delivered the week of October 16. The last four Supers have all had the 4" Z lift for more clearance and run multiple part holders on rotating fixtures on a HRT 210.

Edit: Typos.

[automizer]

Geof or Automizer,
Since both of you have mini's and super mini's I was wondering how big of difference do you see on a cycle time between the two machine with the same program? I know there are lots of variables that can be different but just say its a 8 tool job with a 10 minute cycle on the mini and they you go put in on the super mini is it much shorter? because now you have faster rapids and faster tool changer. I have two mini and am looking at getting a super for the higher rpm spindle.
Thanks.

Geof is right the Supers just fly threw. Sitting at a mini for a week then moving to a super I jump at the first tool change because its so fast. In my eyes the extra cash for the super is worth it.