IH Column

[Ed from NY]

I was just wondering how rigid the column attachment to the base is. From the pictures the column itself is not very deep and it is held in place with 4 bolts.

Here is a pic that shows it well from a nice set documenting a conversion CNC Conversion



I've seen some pictures of resin filled cavities, but did not see any plate welding/bolting type mods.

Have you run into issues with column rigidity?

Also I saw in another thread that Arizona had issues with the ways having high/low areas which prevented the gibs from being tightly adjusted. I have had problems like that before... some people lap it, but the way to really solve it is to have it scraped. It is not a deal killer, but it is something that would need to be budgeted for. Is this a common issue?

Thanks!

[Cruiser]

These columns are as rigid as you can purchase for the $
There was a problem with the old model such as mine in that the dove tail area got thin enough to flex under load of the saddle gib and the weight of the gear box. Gene heard what I had to say about it and very quickly incorporated the new design as is available now. This greatly reduced the flexing and made for a much more stable design, also as part of the upgrade he did, the saddle covers more surface area and should prove much more stable.
As for rigidity in the total of the form, You could put an indicator on the gear box to the table and push the top of the column with your hand and see a small deflection. But, It may show up in roughing but that is why we use a finish pass ! So, in effect this is a non issue !
For the money I'd be prone to say it is a very rigid design and plays the effective role in productivity.

[jetflatline]

I don't know how to measure it, but I do know that it was non-trivial to get the column off of the base. The bolts were torqued down pretty hard, I had to use a cheater to get them off.

[Ed from NY]

Okay, so no issues with facemills right? I have a 4" which takes 7 inserts that I would like to use. Is that too big for this machine?

[saabman]

Yesterday I used a 4 insert 2 inch face mill and got a beautiful finish on Aluminum. Roughing passes at .015 with final a .005. This despite the fact that I have only done a rough tram on the column (mill just recently put in to service)

[arizonavideo]

I use a 2.5" face mill in steel and aluminum and it works fine. I removed the column to do the CNC work it is is all of 300LB or more.

Not counting the mounting flange, at the base the column is about 7" x 8" and closer to 3/4" thick.

I was indicating the other day looking for play and a strong pull of 15 to 20 lb on the head gives about .002" deflection with the head 8" from the table.

I don't know how that would compare to a BP or others.

[Cruiser]

I don't know how to measure it, but I do know that it was non-trivial to get the column off of the base. The bolts were torqued down pretty hard, I had to use a cheater to get them off.

The measurement is of the saddle size, the picture above is the new design. At a glance you can see the round flanges for mounting the head box to the saddle, the older design was all squared off or rather rectangular.
On the new design you can feel from the minor of the doves to the inside of the column and on the inside it is rounded and has added mass where iron was added by building up the pattern for the mold. The older design such as mine is, is sharper and a whole bunch thinner than the new design and allowed the doves to flex under the weight of the gear box and the tension of the Z gib. This made it impossible to pick up the gear box with the gib, and instead it would just squeeze the dovetails, flexing in a bow. the new design took care of this for the most part. That is why I redid my column with rails, So I could pull my gear box up against the slides of column and not be required to put more than just a nudge of adjustment to the Z gibs. It makes the head so much more easily moved by the motor.
I did a test with mine before and after the modifications. The test comprised of a cut with a 3/4" end mill taking a cut of .1" X .75" around a piece of tool shank that was cut off of a destroyed tool holder. It was not the cut I was interested in, but rather seeing exactly what happed ed with the machine. The cut was in fact ridiculous but effective in showing me every weakness involved.
I started the cut at the left front corner and went toward the column, around corner, down the back side, around the corner and back toward the front, and came back to start point.
The cut was very noisy to say the least. It appeared to be doing fine on ends and back side with the exception of a lot of vibration and pulling. It was when I came around to the front side that I saw what I was after. The twist of the end mill, or cutting force, actually lifted the weight of the gear box, the total of the slack in gibs, and commenced to destroy the cutter.
After the rails system was installed the test was run again and it was much quieter all the way around and was pretty much equal across the front side. This solved the problem and I notified Gene of what I did.

The new machine should be fine in a similar test.

BUT, beware that the cut that I did was ridiculous with respect to the size and rigidity of the machine and should be tested before trying to make something that counts, besides the end mills I destroyed were very expensive carbide but used freebies.

As far as using a face mill, as long as your paying attention to the direction of force and your chip loads, It should be fine with the new design machine (new design is close to 3yrs old now). And, pay attention that your gibs are properly set, not too loose or tight. And I do not recommend the grubs being used for any reason on the CNC machines as they will dimple and bow the gib and after that make them extremely difficult to adjust to that perfect setting.
Altho now I am quite happy with my machine as it is now. I often wish that I'd held off a couple yrs to get the new design, but since I kind of tickled the new design into being then >>>>> I wish in one hand and !

[Ed from NY]

Very informative post! Thanks!

Thanks for the tip of selecting a path that puts the column under compression as opposed to tension.

[ksanalytical]

Ed,

I've seen a very similar amount of flex while pressing on the head, however, I measured 0.002-0.003" of vertical change at the tool rather than on the column. Further, I spent a week with a 45 degree 2.5" insert facing cutter (5 tooth) and a 1" plate of Al trying to get the tram 100% correct. No matter how perfectly I aligned the head, I always had a very low ridge between the passes of the cutter. It was under 0.001" high, but visually noticeable and could be felt like a fine hair under your finger. Based on the location is showed up in for a given direction of pass (I tried every type of path), the only explanation I could come up with was that it was caused by flex under load, even with just 0.005" DOC.

I've never tried that with a pro level machine, but I assume it would be difficult to track down the cause (or cumulative causes). It would be great to hear Bob Warfield on this one as he filling the sides of his column with epoxy granite...

Ken

[Ed from NY]

Are the ridges localized or all over. Is there a pattern? Is there a discontinuity? Also is the piece crowned? These things could give you a bit of a clue as to where the problem may be.

Does it sound like it is cutting or kind of raspy. Try a gentle entry angle if you are not using one already.

[ksanalytical]

Ed,

It's just one ridge which marked the transition between passes parallel to the axis of motion. Interestingly enough, if would fade at the end of the cut as the leading teeth cleared the end of the material. This was one of the key factors in my assumption that the flex was induced by cutting force. I can't say there was any crown to it, but the ridge itself could only be measured with a DTI on the spindle so it's not like it was huge. I could tell which side was higher by running my finger across it carefully. I could discern a very slight roughness from one side which was not present from the other. 70% step-over.

I've had my own adventures with IH like many here have... I still think it's an amazing machine for the money. I ran a series of parts recently which involved a 0.38" deep, full width cut with a 0.1875" carbide 2 flute cutter at 4"/min and 3400rpm. The simple fact that I was able to cut ~30' of material like that across the whole production run without any chatter-induced breakage should indicate that the mill is pretty solid. I can't wait to get it back together and cutting again.

Ken

[BobWarfield]

Ed,

I've seen a very similar amount of flex while pressing on the head, however, I measured 0.002-0.003" of vertical change at the tool rather than on the column. Further, I spent a week with a 45 degree 2.5" insert facing cutter (5 tooth) and a 1" plate of Al trying to get the tram 100% correct. No matter how perfectly I aligned the head, I always had a very low ridge between the passes of the cutter. It was under 0.001" high, but visually noticeable and could be felt like a fine hair under your finger. Based on the location is showed up in for a given direction of pass (I tried every type of path), the only explanation I could come up with was that it was caused by flex under load, even with just 0.005" DOC.

I've never tried that with a pro level machine, but I assume it would be difficult to track down the cause (or cumulative causes). It would be great to hear Bob Warfield on this one as he filling the sides of his column with epoxy granite...

Ken

Saw a note from a guy recently said he pushed on the head of his Haas VF-2 with about 20 lbs of force and measured a deflection of 0.00025". We got a little more than that on our IH mills.

The E/G fill doesn't eliminate this weakness, but it helps. I estimate about a 20% improvement in what the filled mill can do versus my second unfilled mill. If the mill is apart for a conversion, its easy to do, so why not? Would I take a working CNC mill apart to do it? Probably not.

Facemills are HP hogs. I have stalled the 2 HP spindle with my 3" Glacern FM45. A 4" facemill? I'm pretty skeptical. If you just want to be able to finish a piece up to 4" in one pass with a very shallow cut, it'll be fine for that. If you have to move much material, you're better off with a smaller face mill. I have a 2" 90 degree face mill that is about right for doing the roughing surface work. I use the FM45 for a fine finish.

BTW, if I had bothered to look carefully at the HP indication in G-Wizard, I never would have stalled that face mill and broken a set of inserts, not to mention knocking the mill out of tram and having to change shorts, LOL. It was just about right on 2HP with the cut I was taking. I have since started setting the G-Wizard HP limit to 1 HP. That gives me lots of margin and makes me think about it harder if I start to do something that takes a lot of HP. G-Wizard will automatically feather back the cut so it only needs 1HP if it can, so it's a painless way to stay on top of it.

The HP pumped into the cut is what's going to cause the deflection. I think about it as if I run a 2 HP cut, that's 100% of the mill's capacity. Something may break and something will definitely deflect. At 1 HP, that's 50%. Things are pretty darned solid there.

Cheers,

BW