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BobWarfield
07-27-2006, 01:32 AM
There has been a lot of discussion about how well made the IH mills are, and particularly about the quill runout. I thought I would take a couple of measurements on my machine (received at the beginning of the year) and share the results. YMMV.

Over the entire travel of the quill, 5", I measured a maximum deflection of 0.0075" on my Interapid indicator, which is much less than the 0.020" in 1" some others have experienced with early versions of the mill. Quality controls must have improved with time.

A couple of other important things to note. A huge amount of that deflection was in the last bit of maximum travel, backing off just 1/2" and using 4.5" of travel, the max deflection falls to 0.005". Over the course of an inch, it is slightly over 0.001", which ought to be fine for most HSM boring operations, but is still not great. For comparison, I found a copy of the Wilton B'port style mill manual somewhere on line and it lists the equivalent spec for that knee mill as being 0.000984", which is less, but not hugely so.

I was also curious how the Z-Axis was behaving, and so took the same measurements moving the Z-Axis with the quill retracted. The results are dramatically better. With my setup, I was only able to measure over about 1/2 the travel, or 10" (need to find a nice big cylindrical square to do better). Over that distance I got a maximum deflection of 0.00075", which I though was quite good. Note that I have not squared the machine (i.e. shimmed the column mounting bolts for squareness), but I had just trammed the machine in very carefully. The equivalent spec for the Wilton is not nearly so good, as they are quoting 0.002362". Another comparison is Tormach, which lists a figure of 0.001378" for 5.9" of travel in their QA spec document, so the IH would have qualified well within that spec.

I took all of the measurements a half dozen times, and found them to be completely repeatable as well.

It seems to me that quill operations can be handled just fine on the IH Mill, but if an extra measure of accuracy is desired, use the Z-axis and these mills are pretty darned good. I suspect an enterprising HSM might find some ways to tune up the quill so it performs better. My mill's future lies with a CNC conversion, and I will definitely look to drive the z-axis off the column rather than the quill for best performance.

I hope this helps those who are interested in understanding this mill's capabilities. I am pleased thus far with the mill's performance, and looking forward to continue to test its limits.

Best,

BW

bill south
07-27-2006, 09:56 AM
Bob;
Have you decided how your going to power the zaxis??? My lathemaster is killing a 3/4" ballscrew due the weight of the head. I used a Warner precision screw rated at 750# but the weight of the head and the connector used to connect the ball nut to the zcarriage (stock connector modified to accept the ball nut) is causing a lot of friction and torque on the ball screw. The initial very low backlash increaseing almost daily and is up to about .050". This weekend I'm planning on dissassembly, rebuilding the ball nut and adding gas springs to help matters out (wish I had done that initially!).
Anyway, if this doesn't work, I was thinking of converting to a powered quill design. Now my question for you, have you seen a design for a powered quill????

Thanks.

Bill

BobWarfield
07-27-2006, 10:19 AM
That's an interesting problem you've got there Bill. Are you sure the ballscrew is at fault and not your angular contact bearing mounting arrangement? I would check your gib adjustment carefully as well. Also note the couple of mods Aaron makes to these mills around the Z-Axis to tighten them up. They're documented on his site. Check out the CNC conversion kit's installation instructions, which are on the site, for more details.

Sure seems like something is loose to get that kind of play!

In my case, I ordered Aaron's kit rather than engineer my own. It hasn't arrived yet, which is fine, I want to be very familiar with this machine on a manual basis before converting.

Best,

BW

Randall
07-27-2006, 12:16 PM
Bob
your deflection mirrors mine. In fact My deflection didnt increase till around 3 inchs of extension on the quill. I put the 3hp 3phase motor on mine with a VFD and I am really happy with it.
Randy

BobWarfield
07-27-2006, 01:53 PM
Good to hear from you Randall. I'd like to try the bigger motor as well. I was just buzzing through 6061 aluminum with a 1/2" roughing EM the other night and could tell the thing wanted more rpm. It was very smooth and you could turn the handwheel just about as fast as you'd like.

Best,

BW

Ron111
07-27-2006, 02:22 PM
Bob,

Good piece of work. Have you started lapping the ways and have you been able to check your table for flatness.

I'm sorry, Bob. I know it seems like I'm trying to give an extremely busy man, more tasks.

I'm also courious as to where Bill's backlash is growing. With Aaron's Zaxis Mod, I believe he stated the the attachment piece that goes through the plate, that supports the head, can pull all the way through (I can't think of the correct name for this Z axis ball nut mount). If that is the case (assuming that I understand correctly what he said) then without that mod it could be dangerous, if this piece pulled all the way through and it could allow the head to drop.

I hope that I stated my concern that correctly.

I was just giving Z axis backlash some thought and I would think that with the Z Axis, and the weight of the head, that you would have a minimal backlash, where the weight of the head would essentially preload the ball screw and on the angular bearings. I could see having backlash when using a single ball nut with a Gas spring, but am having problems visualizing backlash with 200lbs riding on the ball nut and the angular bearings.

Feel free to straighten out my thinking process!!

Ron

BobWarfield
07-27-2006, 05:18 PM
Bob,

Good piece of work. Have you started lapping the ways and have you been able to check your table for flatness.

Ron

Ron, I haven't started lapping ways and won't until I'm about ready to perform the CNC conversion. I would like to take some more measurements on the machine, and will try to get around to it as I find time from my other projects. Perhaps I can just add them to this thread. I hope others like Randall will feel free to add their experiences as well.

I think there is a lot of interest in the IH mill, and this is so far the only forum for it that I am aware of, although the Lathemaster mill is similar. I think it's kind of up to us IH owners to keep the flow of information going so others can evaluate whether to join the ranks or try another solution. I must say the little Sieg mills are extremely cool as well and we've been seeing a lot of good posts around those machines.

Best,

BW

Randall
07-27-2006, 05:58 PM
I did lap my ways and it was fun to do. By taking it a part I learned alot.
The lapping made a huge difference in feel when cranking the handles.
qwhenever I do the cnc conversion i amy do it again, I went light on the first round.
Randy

Ron111
07-27-2006, 07:59 PM
Bob,
It's that's massive work area that keeps me coming back. I can just envision loading the table with multiple vises, and using the fixture offset tables in MACH 2 (or Mach 3) and sitting back for an hour or so and watching it work. But like I say, I keep coming back and reconsidering the IH.

Ron

Ron111
07-27-2006, 08:11 PM
Randal,

"I put the 3hp 3phase motor on mine with a VFD and I am really happy with it."

What all did that take, how big of a project was it, and when you plan to cnc your mill, have you figured out how to control the spindle speed with Mach3.

What is your high end on spindle speed? Where did you get your VFD and your motor.

If you have time maybe you could give some us info on what it takes to do this modification and maybe a pic or two.

Thanks,

Ron

BobWarfield
07-27-2006, 08:42 PM
Bob,
It's that's massive work area that keeps me coming back. I can just envision loading the table with multiple vises, and using the fixture offset tables in MACH 2 (or Mach 3) and sitting back for an hour or so and watching it work. But like I say, I keep coming back and reconsidering the IH.

Ron

I agree Ron, and think that sort of stuff is very cool. I always read everything I can find on fixturing and other production work. Not sure I'll ever need to make a bunch of anything, but it's quite fascinating. I've been tempted to just leave my 4" vise and 8" rotab all set up on the mill as well. There is certainly plenty of room for that.

RE your thought of loading a bunch of vises and sitting back, I have sure seen this done in a lot of the production-related articles I've read. I've seen Kurt vises (the 4 inchers would be nice and smaller for this, I think 4 would fit on the IH table), grinding vises (even smaller and hence more parts fit), but how about these collet indexers:

http://www.thewarfields.com/img/Toys/MachineTools/OthersProjects/RowOIndexers.jpg

That's a setup that HuFlungDung did for some sort of a job he was doing. I've done a little bit of work with collets on the mill, just with simple collet blocks in the vise, and I have to say I love them. Seems like you could really bang out some parts using a setup like Hu's. It's tempting to consider that even if your part isn't round, a round boss plus a CNC program to deal with what's above the collet might not be a bad way to go for small parts. The boss could be cut off later, and "round" indexes so nicely!

Best,

BW

Ron111
07-27-2006, 09:05 PM
Bob,
I've seen those collet fixtures in the JTS catalog, don't have an idea what their used for. So, what are they used for?

Is that the hand of HuFlungDung, my boys get a kick out of his cartoon charactor.

I currently use a 4inch vise from JTS that I have been pleased with for $58 & shipping. Same vise that enco sells for $90 or so with the rotory base, I removed the base. They also sell a 3 inch that I've considered. You could really load up a table with those (they must weigh about 15 lbs to 20 lbs each)

Also I've looked at the 4 inch double vises for $157 & shipping. But have never seen one in use here on the cnczone.

Have you ever looked at using fixture offset to do repeat milling at different locations. I played with it and it works welL

Take care

Ron

BobWarfield
07-27-2006, 09:35 PM
I look at collets as just a really precise and fast way to deal with round things. There's a book by Hardinge available on eBay that has loads of great information on them. They're handy for both workholding and toolholding. Whenever you have to deal with something round on the mill, it's worth thinking about whether collets are a better answer than v-blocks or v-block jaws in the vise. The collets themselves can be a bit expensive, look for a set on eBay. I was able to find a nice complete set of 5C's for just under $200 used.

ER collets are nicer than 5C's, because they have a wider gripping range, so you need fewer collets, however I don't see quite as much tooling available for them. In any event, I have an ER32 chuck for the mill with an R8 shank that I'm also fond of.

A small set of 5C's and a collet block set would let you get started doing things with collets on your mill. One of those collet fixtures as shown is the next step up after that, and eliminates the need to hold a block in your vise. OTOH, they're probably not worth it unless you need to run off a lot of round stuff--easier just to use a block in the vise. A spin indexer lets you index the rotation of the collet, and would be the next step up.

Anyway, if you can get past the initial cost of a set of collets, they're darned handy to have around the shop.

Best,

BW

BobWarfield
07-29-2006, 10:56 PM
With 2 out of 3 axes on my inexpensive DRO project working now, I took a break from fabricating DRO brackets to measure backlash on the X and Z (quill only) with the aid of the DRO's. Basically, I turned the handwheels a full turn and back to "0" in one direction, zeroed the DRO for the axis, and then made a full turn in the opposite direction. Since I reversed at the beginning of the turn, a full load of backlash would be built into the movement. I then compared the DRO reading with what it should have been given a full revolution of the dial. The results were interesting.

First, X-Axis backlash was 0.010" and very repeatable. I can see where that would be extremely ugly to deal with on a CNC converted mill.

Second, the Z-Axis/Quill backlash was quite variable. It ranged from a low of 0.004" to a high of 0.014". I finally tracked it down to some play in the clutch mechanism for the handlebars. Seems like no matter how tight I made the nut, there was 0.010" of play there in the bars. Now there has to be some way to work that play out of there, or at least the majority of it. I would think if nothing else it could contribute to quite a lot of chatter as the endmill bounced up and down up to 0.010" and vibrated.

Does anyone know of a fix for this problem on the IH Mills? I'll eventually get around to taking it apart and figuring things out, but I have to finish the Y-Axis DRO and I also got a smoking deal on a power feed for the X-Axis that will need installing.

So many projects, so little time!

Best,

BW

Randall
07-30-2006, 11:19 AM
sorry about taking solong to answer.
The shaft of the motor needs to be turned down and new keyway made. I got two quotes 250$ and 20$, I went with the 20$. I still had to mount the motor core in my lathe to take just a little more off the neck to get a full seat.
I purchase the vfd from automation direct. I bet close to 400 to 500 for both but I can give you an exact price tommorow.
Randy

Randall
08-01-2006, 02:25 PM
OK guys this is where I got the 3hp motor, bolts right on after the shaft is turned downed and shortened. #192084

http://www.electricmotorwarehouse.com/metric_B5_Flange_mount.htm

This is where I got the VFD, I should have gotten the 5hp instead of 3hp and the 5hp will take single phase in.

http://web1.automationdirect.com/adc/Shopping/Catalog/AC_Drives_-z-_Motors/GS2_(115_-z-_230_-z-_460_VAC_V-z-Hz_Control)/GS2-23P0

Hope this helps, I bet the GS1-23po could work.
Randy

Runner4404spd
08-01-2006, 05:18 PM
who turned down the motor shaft?

Randall
08-02-2006, 01:17 PM
I got two quotes on turning down the motor shaft. The first was a motor reapair shop and the price would have been 200 to 250$. Somebody recomended me to a machine shop where an older man didnt give me a qoute but I had a hunch it would be less, 1 week later I picked it up and I asked him how much and he said 20$. He actually let me watch him doing some work on the lathe and it was mesmerizing watching him. When I got the motor back it wouldnt guit seat all the way so I had to turn it down right where it exited the case and it was easy to do. I hope this helps. Remember though it voids your warranty to put A 3hp motor on the mill.
Randy

BobWarfield
08-02-2006, 01:38 PM
I got two quotes on turning down the motor shaft. The first was a motor reapair shop and the price would have been 200 to 250$. Somebody recomended me to a machine shop where an older man didnt give me a qoute but I had a hunch it would be less, 1 week later I picked it up and I asked him how much and he said 20$. He actually let me watch him doing some work on the lathe and it was mesmerizing watching him. When I got the motor back it wouldnt guit seat all the way so I had to turn it down right where it exited the case and it was easy to do. I hope this helps. Remember though it voids your warranty to put A 3hp motor on the mill.
Randy

I guess the next question, since we have already voided the warranty, is how hard did it look to turn down the shaft yourself if you have a lathe? I wonder what kind of swing you'd need for one that size.

BTW, another source of VFD's that seems to have decent prices is:

http://www.driveswarehouse.com/

I've got a motor sitting in a box that needs the shaft turned as we speak. Was planning to wait until I disassemble the mill for CNC and decide whether to convert to belt drive. If I'm doing the latter, I can as easily not turn down the shaft and make the pulleys fit it. I guess Aaron has a belt drive kit on the way at some point.

BTW, have had no probs running max speeds on the out of box motor. The smoking blue meanies (blue chips) go everywhere very fast--wear a face shield and long sleeves! LOL

I also trust you IH guys are following the thread elsewhere on those cool Proxxon spindles that Tormach and others offer. 20,000 rpm! The thread shows some calculations that indicate it should be fine for 1/8" endmills in aluminum power-wise. I'd like to see that in action. Somebody mentioned hooking up 2 of them so you could make 2 parts at once. There must be enough room for 4 or 5 on an IH Mill! (chair)

Best,

BW

WilliamD
08-05-2006, 01:34 PM
I've had the IH mill since March of this year and am working on the CNC retrofit. We dismantled the mill and lapped all the ways as was recommended. Unfortunately, we did not take any measurements concerning accuracy. But after lapping, I swept the entire length of the table with an indicator attatched to the spindle, and it didn't go out more than .001". I was pretty happy with that. It definetly varied between the .0001" and .001", but definetly good enough for my purposes. Also, I measured my z-axis spindle deflection, and it was within .001" the entire travel also. Again, definetly moved between .0001" and .001", but definetly good enough for my purposes. I did not measure the column straightness, as I have not yet trammed the mill. But at least things seemed pretty flat. Only slightly negative thing I have to report is that the runout on the spindle is a bit more than I'd like. I'm definetly looking into converting it to a belt drive and replacing the bearings in there. I'd even love to convert to a BT-30 or something similar, but one step at a time. :rolleyes: My basic CNC conversion should be done by the end of the month, so I'm looking forward to posting picutres and video. :cheers:

Randall
08-06-2006, 11:50 AM
Bob I have the 9by 20 lathe. After you take the motor apart its a piece of cat to put it in the lathe. I would Have done it myself but I didnt get the lathe till after the process was started. This is A guess but I believe the shaft was 21mm and need to be turned down to 19mm.
Randy

BobWarfield
08-06-2006, 12:30 PM
Thanks Randy, I may just give it a try.

Best,

BW

Ron111
08-07-2006, 07:52 PM
Randy,

I would think that it would be akward to get the armature mounted in the chuck, so I guess I'm not visualizing something correctly. But, maybe I just got it!! Is there enough shaft to chuck up on the short end of the armature and then use the live center on the end of the shaft that you need to turn down? If so, maybe I understand. Forgive my ignorance, but I am a Chiropractor, not a machinist!!!

Ron

BobWarfield
08-07-2006, 08:30 PM
Ron, this diagram will give you some idea of what you are dealing with:

http://www.motoruponline.com/images/effmotor.jpg

If you Google on "three phase motor disassembly", there is no end of online courseware and videos available that discuss routine disassembly of the motors. I'm more inclined to just get after it with a wrench, but real resources are available. Doesn't look too hard.

Best,

BW

Cruiser
08-08-2006, 01:35 AM
turning down the end of the shaft is easy, best way is with a tight fiting collet and support the other end with tail stock and small live center, tool point will have to get in close to the center. just make sure that you measure well and do it right the first time or you'll be spending some money having someone else weld it and return it true. the motor comes apart real easy and reassembles just as easy

Runner4404spd
08-08-2006, 08:08 AM
did you just mill the key way after turning it down?

Randall
08-08-2006, 12:04 PM
cruiser is right on thats exactly how I mounted it . you take the armature out of the case and remove the cooling fan then its easy to chuck up. I didnt do the key on mine a machinist did. but he ground a new key way on the oposite side and it worked great.
Randy
PS sorry for the poor layout of this message I'm doing this at work and its cazy.

CNCPlastic
08-11-2006, 01:14 PM
Bob;
My lathemaster is killing a 3/4" ballscrew due the weight of the head. The initial very low backlash increaseing almost daily and is up to about .050".
Bill

That sounds like the funky Z axis slide to screw assembly issue. Mine had .020 slop from the factory. The Z axis slide is not attached to the screw, thats the problem. There is a bushing bolted to the screw which sticks out and into a hole bored into the slide. This is kind of a clunk/clunk up/down fit, rather sloppy plus its cast iron on cast iron with no real way to lubricate it. Aaron's mod lets you bolt the slide directly to the screw with a rather large bolt. That eliminates 100% of the slop. Screw alignment becomes critical though because there is no longer any slop in the assembly. With the cnc conversion the ballscrew is only attached at the top which gives you a little bit of play at the bottom of the travel.

The head on this machine is quite heavy and hangs out over the table. That thing weighs like 250 pounds with the motor. I counter weighted mine with 180 pounds which made a big improvement and took a lot of stress of the axis.

Cruiser
08-11-2006, 09:55 PM
Hey there CNCPLASTIC, I'd really be interested in hearing more about your counterbalance system and how it reacts with the drive for starting and stopping. I can't help but concider the laws of phisics applied in so far as added mass to the system which must increase the load to the axis drive even tho it is somewhat in a balance. anyway i'd like to hear some first hand account as to the benefits v/s any shortcommings. how about it, you can make it a tutorial of sorts, and if your convincing i may try it on my IH mill and Thanks !

CNCPlastic
08-11-2006, 11:03 PM
Hey there CNCPLASTIC, I'd really be interested in hearing more about your counterbalance system and how it reacts with the drive for starting and stopping. I can't help but concider the laws of phisics applied in so far as added mass to the system which must increase the load to the axis drive even tho it is somewhat in a balance. anyway i'd like to hear some first hand account as to the benefits v/s any shortcommings. how about it, you can make it a tutorial of sorts, and if your convincing i may try it on my IH mill and Thanks !

I counter balanced the head using two steel cables attached to a bar which runs under the head, its positioned about half way between the column and the front of the head. The cables run straight up vertically to pulleys bolted near the ceiling, then horizontally to a second set of pulleys towards the rear of the mill, then straight down to the 180 pound weight behind the mill.

I can't speak to the physics of counter weighting. All I can say is that before counter weighting the head I had to leave the gib rather loose else the stepper motor would lose steps on up moves. After I counter weighted the head I was able to tighten up the gib quite a bit and retune the stepper because it wasn't working nearly as hard as before on up moves.

Many VMC's are counterweighted, some use weights, others gas cylinders, or more recently some are counterweighted with servo motors.

I think in general terms its best to have improved balance when it comes to the amount of force required to move the head up versus down. Perfect balance would be nice but I did not take it to that level. I felt 180 pounds was sufficient enough of an improvement.

Charles