[GT390]

Most VFDs can generate frequencies up to 400 (some higher) which would 6.667 times over speed your motor. The motor would likely not hold up at that speed.

Yikes, that means I have a potential flat out speed of 26,600 rpm at the spindle ! I am going to have to rig up a tach to see what I am actually spinning the spindle at

[Bob La Londe]

A tach on the spindle can be handy if you are running software for things like rigid tapping or turning threads on a CNC lathe, but for general milling real time feedback isn't really necessary. A hand held optical tach and a white paint marker is all you really need. Its not going to vary once its set. On a CNC mill you would use a breakout board with a speed controller of some type. Whatever your VFD will accept. Usually 0-10VDC signal voltage. Then you adjust as needed so you are fairly close at any commanded RPM. On my Hurco motor it had a cooling fan motor inside the main spindle motor housing, and it was rated for 3hz to 120hz which was 96 RPM to 3600 RPM. I programmed those limits into the VFD. I was never dead on for RPM, but I had a couple sweet spots.

An induction motor does a fair job of self correcting for speed under load, by drawing more current. You will get consistent repeatable speeds based on the frequency you feed it. They can experience motor slippage, but its only really significant if you are loading your motor near its max at a particular speed.

If you are using Mach3 you can set a max speed for each pulley. The way to find that max speed is to put the spindle in that gear, and feed the motor the maximum frequency you intend to, and then read the speed with your hand held tach. Enter that number in Mach 3 for that pulley number.

Most quality 3 phase motors can handle from half speed to about double speed. An inverter duty motor may be able to handle a wider range, but probably not much slower unless it has an independent cooling fan since it will not self cool at slower speeds. Remember at slower speeds it will have less torque and less power. Its why big VMCs have 15-30HP motors. So they still have decent power at low speeds. A Chinese high speed spindle motor for example likes 8,000 RPM to 18,000 RPM. Some may say 0-24,000, but 24,000 is really fast for the bearings, and it won't have any torque at all at slower speeds.

[GT390]

Thanks Bob, for the explanation, that is helpful, and thanks Dan for taking the time to post the diagram, I have the machine back together again with the new bearings in the head, I realized that the spindle can be removed from below without taking the head off, so decided to rebuild the head today, made the new cast bearing retainer on the lathe last night, and it worked out just fine, accurate machine were wanting $285 for a used one ! So I am back up and running again, but do intend to do the spindle bearings when I can source some. With the new bearings in the head and drive the machine is now much quieter. Here are a couple of photo`s, excuse the state, its just done a bit of work !

[Bob La Londe]

Well, the high speed Z was ok, but the other machine I bought to take the place of the Hurco just isn't rigid enough. When I found a chance to snap up a quill for the Hurco I grabbed it. The chrome is nearly perfect. Sure it has lines, but nothing I can measure. The problem is the bearings. They don't sound so good, and I can't figure out how to get it apart. I pulled a little set screw on the side of the quill and I can see threads underneath for the front retainer (I think), but it won't move. On the back there is a nut with a lock tab washer. I flattened out the tab that was locking, but the nut won't move either. If its not one thing its another. LOL.

[Bob La Londe]

As I mentioned I setup a high speed Z on the Hurco and it worked fair, but I really miss the rigidity if that mill for heavy work as compared to my new mill so when I had a chance to get a quill with decent chrome and no score marks I snapped it up. I struggled with getting it apart. The rear nut took several blows with a drift and a deadblow hammer to break loose.

The front bearing retainer wouldn't move at all. I was afraid of tearing up the spanner holes by pounding on them with a drift so instead I made a spanner for it. Then I clamped up the quill in my aluminum vise with a couple pieces of MDF as padding to protect the chrome. Hand pressure with my home made spanner just spun the quill in the vise. (Good thing for that MDF huh). Then I smacked the handle of the spanner a couple times with a ball pien and the reatiner loosened right up.

Now to decide if I can get away with just throwing some Kluber grease in those bearings or if I need to replace them.

The home made spanner worked well, but its kind of heavy. Still I am considering making the other end to fit the spindle nose for those rare times when I need a little helper to release a tool holder. Also, if I make it into a tool I'll use from time to time I'll still have it if I need to open up a Hurco quill again.

[Bob La Londe]

Well, I pressed the bearings off the spindle shaft today and looked it over.

I have not washed the grease and dirt out of the bearings, but one of the
ACBs doesn't feel wonderful to me. I figured as long as I have it apart I
might as well replace all the bearings if they don't cost to much.

On the back its got a Fafnir 206PP. Seems to be pretty easy to find.

On the nose its got a pair of New Departure 20207 ACBs. Those also seem to
be modestly easy to find. What got me is they don't seem to be a matched
set or anything. There are no alignment marks and they are both marked
identically. They are just back to back against the spacers.

It does have both inner race and outer race spacers between the ACBs and an
inner race spacer between the ACBs and the rear bearing so preload is pretty
much predetermined.

None of these bearings are particularly expensive. Seem like an off the
shelf bearing, although most I found are new old stock rather than new
stock.

Am I missing something? Is it really just as simple as it seems? Just buy
a couple New Departure 20207s and a Fafnir 206PP and press all the new parts
back in place?

[GT390]

The new bearings I got for my kmb1x are fafnir 2MM207WIDUL, these are what was fitted by Hurco, the box says C1 super precision. I have not fitted them yet, but as far as I can tell the preload is predetermined, and was told they may or may not have markings, if they do have a "0" mark, then align them

[Bob La Londe]

Just finished the "Hurco Spanner". Well almost finished. As you may recall I made a spanner for removing and tightening the nose bearing retainer in the KM series 3.375 quills. I'll probably only ever need to use it a couple times so I decided to make the other end useful on a day to day basis, so I would be more likely to find it when I do need it. I designed and cut the other end as a spanner to snug and release tools from the kwik 200 spindle. I rounded the fork/pin/hook on the belt sander to roughly fit the curved bottom of the slots. I want to case harden the end so it will not wear out to quickly. I've got some Cherry Red around somewhere.

[Bob La Londe]

Here is the DXF file I used to cut both ends. Its in 3 or 4 layers (I forget at the moment) so if your software just shows everything all together and doesn't allow you to turn layers on and off easily it will be a bit cluttered looking.

[Bob La Londe]

I am getting close to putting the head back together and I need a new spindle drive belt. At first glance it was ok, but up close I can see a "cut" through that could go at any time. Anybody know exactly what belt this is likely to be and where to get one?

[Bob La Londe]

I finally got around to putting the (new to me) quill back together so I can
take the Hurco mill back to its original configuration. Seemed like one
thing after another. Been busy with customers and family of course, and
then when I had everything (I thought) read to assemble the push tube on my
12 ton press decided to collapse. I can't complain. I bought it used 15
years ago from my dad when he upgraded to a 20 ton. I got a lot of use out
of it. I figured what the heck. Time for me to upgrade as well. Nobody
had one in stock locally. I ordered one a few weeks ago. They keep giving
me excuses, but no press. Finally, I got tired of waiting and repaired my
12 ton with a solid rod instead of the hollow pipe it had before. I also
added a reinforcing plate that guides my push rod a little better than the
original setup. Should last a few more years, and who knows, my new 20 ton
might show up some day.

Anyway, I put the quill back together today and noted that the locking tab
washer that holds the retaining nut in place is chewed off. The inner tab
is almost totally gone. I suppose I can cut one, but I don't think I have
any sheet as strong as the steel used for that washer. I figured I'ld buy
one. Only thing is I haven't a clue where. I tried McMaster, but either
they don't have any, or I don't know what they call it.

Picture:
Fishing Arizona & The Colorado River - Tab Washer for Bearing Retainer Nut

Now, to go rummage around in the shop and see what I have that might do.

[jalessi]

Bob,


Its called a KM bearing lock washer.


J.W. Winco, Inc. - Metric Size, Bearing Lock Washers

Maryland Metrics: MB lock washers

Jeff...

[Bob La Londe]

Yep, thanks. Once I figured out exactly what to call it I didn't have to much trouble finding a Timken part number that should work. Timken TW106. Motion Industries should have me one early next week.

[Bob La Londe]

Well, I got the new quill assembled... mostly. I decided to finish tighten the front bearing retainer, and the rear retainer nut after mounting the quill in the machine. It doesn't go. Interestingly I found a Hurco service bulletin, that mentions honing the sleeve in the head to match a new quill. The concept of honing a precision bore really bothered me. I was only familiar with spring loaded cylinder hones like you might use to break the glaze in a brake cylinder or a piston hole in an engine block. I didn't realize that there were "fixed" stone micrometer adjustable hones. Maybe I've seen them before, but they never registered. I've got one coming with 3 sets of stones and wipers.

So, I am waiting on yet another part to put this mill back together. LOL.

Now in the process of getting this together and back apart again I noticed a ring of crumbling material around the bottom of the sleeve for the quill. It feels like cork. Upon doing some research I found that some knee mills have a "wiper" on the quill. I assume its to try and get it to retain way oil for a longer period. Since I do a lot of 3D it makes sense to keep the oil on the quill as much as possible.

I did some more searching and found a what looks like a fiber wiper for a Bridgeport on Ebay but no cork wipers for Hurco or any other brand. I am wondering if this is a part I might be better off to just make.

[Bob La Londe]

Well, the sleeve turned out to be amazingly hard. I honed it today. Took me a while to figure out how to adjust the hone, and a while to put enough pressure on the stones to do anything. I wound up running the hone through the sleeve a dozen times. The last time I put quite a lot more pressure on the stones than I originally thought was prudent.

Each time I pulled the hone, carefully wiped out all the grit and honing oil, hand lubed the sleeve with way oil, and then tried to push the new quill through the sleeve. I now have it so I can just barely push the quill up and down in the sleeve by hand with a lot of hand force. I grabbed ahold of the spline shaft and put serious force into it with my hands in a back and forth motion and I do not feel any play at all. Not even a hint of play. I am sure there must be some, but it sure feels good.

That's not all I did today. I also finished putting my shop air back together and upgraded the whip from the compressor to the wall from 1/4" fittings to a larger one with 3/8 fittings. I have not had any issues with adequate air flow in the shop, but I figured I'ld tackle that before I did. I've been without shop air since before Christmas. My filter regulator split at the bleeder valve, and the replacement I plumbed in was a different pipe size. Seemed like I was always one part short of fitting everything back up.

I also repaired an overhead door in the shop. Its got a jack shaft motor, and something got pushed out on one of the shelves enough to twist a roller mount and cause the cables to partially jump off the spool. I've had jack stands under the door for safety since Monday morning since it would not go up or down. LOL. I've just been to busy until today to do anything about it.

So after finishing those things tackling the quill installation was just one more thing. I hope its as good a job as I think it is.

I may start putting the head back together tomorrow. I think I am done in the shop for today. I'll probably pull the quill out one more time and re-clean the sleeve to make sure I didn't miss any abrasive grit from the stones. I think some might still be laying in the lubrication grooves.

[Bob La Londe]

It has set for a while. The Charter Oak machine has been doing all of the paying work, but I sure miss the Hurco. This last week I put the elevator back on, and the quill would not move. Oops. I loosened the quill clamp, and then I individually adjust all the elevator rollers one at a time... twice, so they just barely touch and roll. Then I tightened up the quill clamp again. The elevator car and quill will fall almost full travel now under its own weight. I have to say the quill has never ever moved this easily before. I got the ball screw, servo motor, and belt installed, and it now has enough mechanical drag to stay in place. So... just for ****s N giggles I plugged in the encoder cable and torture tested it for 500 iterations or so. It tested to 250 IPM and 30iss. At 300 IPM it faulted. Then I backed it off to 200 and 20 to match the other axis'. I might actually be able to run all three faster, but 200/20 is pretty good. When I did this retrofit I figured the current control POT on the servo rotated clockwise to go up. It doesn't. Up is counter clockwise. I had them turned all the way down. LOL. I'm going to leave them at 200, but I might do some acceleration testing. I do a lot of short move 3D work and higher acceleration would improve my machine time on most jobs.

Testing at 250/30
Testing At 250/30 - YouTube

Today I had to figure out how to get the spindle motor back up on the head. A cherry picker did the trick. I lifted the motor by the side ring up above its location and had my wife lower the boom as I muscled the motor into place. It actually went much easier than I expected. Its got a new spindle belt and its just waiting on me to switch back to the original Mitsubishi VFD and wire it in. I am not to sure I trust the VFD that I used for the high speed spindle for this big 5HP Leland motor.

Now I have an issue I would like some help on. A spindle brake. There is a pneumatic brake on a disc on the motor, but my past experience shows the moment I have to use a spanner to release a tool holder its not strong enough. I've been playing with a couple ideas. One is a pneumatically actuated spline socket that comes down on the top of the spindle to lock it from turning. I would make it spring loaded so if it didn't line up it would push back until I turned the spindle, and then snap down to lock the spindle while I pop the tool holder loose. Another maybe simpler idea is to get a stronger brake caliper for the disc brake. I'm not really sure how I would implement that. My first concern on that is the amount of force I would be putting on the belt when I put a spanner on the spindle to pop a slightly stuck tool holder out. Ideas? I must not be the only one to face this problem.

[Bob La Londe]

Its been a while since I've posted here. I have just forgotten. The machine is running. I've cut a few dozen jobs on it. The surface finish with my home rebuilt quill and my inexpensive new old stock New Departure bearings is better than the old quill. Its quite good actually. I spent quite a lot of time doing a run in on the new bearings once I got the machine going. I spent almost a whole day running the spindle up in 500 RPM increments from 100 RPM to 3600 RPM and then back down again. I've been running it almost exclusively at 3400-3600 ever since and it is barely warm to the touch even after running continuously for several hours.

The Kwik 200 spindle spanner is really handy. I wish I had made one a long time ago. I do wish the spindle brake held a little better. If the tool is a little sticky it will not hold. The pneumatic brake is really only useful for stopping the spindle in the event of an e-stop, and not much more. It doesn't leak and hte pads look good so I really don't know how tool changes were done on this machine in the past. I've been using a pair of locking sheet metal pliers on the disc for tool changes. I'm still playing with ideas for a quick engage release brake, but I am about settled on a bicycle style disc caliper with a wedge latch. I'll probably make it myself so I can put some HUGE rubber pads on it. I figure if tiny little rubber pads can stop a bicyclist some big pads should be able to hold a spindle.

I had some fiddly stuff with the Gecko servo controllers the other day. Never could figure out exactly why it was faulting exactly, but stiffening up the I setting on one of the drives seemed to to do the trick. In the process I decided to try and isolate the drives so I could atleast tell which drive was faulting. I separated them each with their own reset switch and each to their own input on the break out board. The separate reset switches worked ok, but one drive doesn't even have the ability to pull up the input on the C23 breakout board. I guess when they were all tied to one input between them they could put it up. Pretty sad. I need to make a low current logic gate in order to pull up a low current logic gate. LOL. The G320X drives are ok for the price. Really isn't anything else that compares at the same price, but they really are bare bones leave you in the dark if you have a problem. No response from GeckoDrive either. Not on their board here or by direct email. I've got a dozen G320X drives (some brand new) and a couple G540s and I can't even get a basic response from them when I have a problem. I think I can going to sell my spare G320x drives and try Larken's Viper 200s for future servo projects. They cost more, but the claimed specs are MUCH higher, and they have real diagnostic capabilities.

That's about it.

Oh, almost forgot. The screw cover plates for the Y somehow got bent up and whacked the rod bracket for the X axis proximity sensor off the back of the table. I had to make a new one. The cover plates just came out for now. I am using a piece of Buna rubber for a way cover in the front, and a piece of cooler door plastic curtain for a way cover in the back. Hopefully they will keep most of the gunk off the screw.

[purple_jeep]

Hi Bob,

In case you are still having issues with the spindle brake, what I did was strip it down clean and rebuild it. I have the pdf manual and parts breakdown for it if you need it. Heitek in Phoenix can supply the parts, all up I spent $45 for everything but new discs (mine like yours are fine).

Also are you using the original Air system as the brake needs the oil lubricated air supply from the Wilkerson regulator. Don't remember the pressure off hand but I have it on the drawings at home.

Cheers

Chris

[purple_jeep]

Air pressure for Brake from factory should be set at 80psi.

Cheers

Chris

[Bob La Londe]

Its set at 80 PSI. Not using the stock regulator, but yes using a full FRL. Have also tried pressures upto 125. Still not strong enough to change tools.