Member postings for John MC

The Quill was straightforward to remove.

The quills key (to stop rotation) is an M10 grubscrew locked in to position with a nut. All of this is down a deep counterbore that is too small to get a socket on the lock nut. I made a new locknut with a smaller AF dimension so a slim socket could get at it.

With the quill on the bench I removed the spindle. No horrors here. I fitted an oil seal in to spindle dust cover. The outside diameter of the spindle is 45.5mm so no seal available. I fitted a 45mm I/D seal with a 68mm O/D, it seems to have the flexibility to cope with the oversize shaft.

The bearing adjustment was a very poor arrangement, a slotted nut held in place (hopefully) with a tab washer. Something very common on these far eastern machines. I made a theaded ring with a split the can be locked in place with an M6 cap head screw.

As can be seen from the photo it was necessary to machine a small slot to give access to an allen key. This arrangement gives a far more positive clamping force than the original arranement.

The tapered roller bearings need to be adjusted with, ideally, zero clearance. In practice difficult to achieve so aim for a slight preload. It won't hurt the bearings and will improve rigidity.

I checked the fit of the quill in the head, good, the only play I could find was when the quill was almost out of the head, beyond where the normal travel would go. If there was play then, depending on the amount of play I would have had the quill decoratively chromed if play was minimal. Indusrial chrome for big clearance and honed the head bore to suit. I also considered slitting the head so the clearance could be adjusted.

The quill lock is a good arrangement poorly executed. The locking handle, extended to clear the electrical equipment box gave very poor feel as to how tight or otherwise the clamp was. The lock itself is two pieces of cast iron with crude chamfers that pinch the quill to lock.

I machined a radius in to the two clamps equal to the radius of the quill. The photo shows the arrangement for doing this, the tube in the foreground was use to set the boring head to the correct radius to do the job.

I fitted a "loose" spanner, captive on an extended nut to act as the clamping lever.

There was, on the end of the pinion shaft a thumbscrew, all it seemed to do was hold the return spring in position. I discarded that and fitted a bolt and washer arrangement to hold the spring in position. I also fitted a grease nipple for lubrication. I also made sure lubrication was taken care of at the other end of the quill pinion shaft. I adjusted the return spring to just be able to carry the weight of the quill rather than sending the quill flying back in to the head as it was as purchased.

The pinion shaft had no proper axial location other than the thumbscrew adjacent to the return spring. I made a collar to fit around the shaft that located the shaft properly.

I decided at this point to give the machine some use to settle things down. Then have a look at the various alignments.

Ps. Sorry about some of the photos being on their side, how do you sort that?

Before opening up the gearbox I decided to run the motor. I bought the 3 phase version so I could use a VFD to increase the speed range aswell as use the variable speed option.

The head was sat on the workshop at this point in a wooden cradle. I connected up the VFD with the help of a couple of forum members. Would have been easier if the instructions for the VFD were correct!

I ran the motor from 5 to 80 Hertz, all seemed well, reasonably quiet and gear selection okay.

So far so good. I removed the motor then lifted the top off the gearbox. I've seen some real horror stories about the muck found in gearboxes of these machines. None of that for me, thankfully. The only thing of concern was a circlip lying in the bottom of the box. The other circlips were all in place so I guess whoever assembled the box dropped it, then, rather than retrieve it just grabbed another from the parts bin.

I drained the oil, very clean but less than an hours running. I extended the drain for the box, oil changes will be a lot less messy in the future! I always fit a magnet to an oil drain plug but having extended the drain it would be too well shielded so I drilled and tapped a hole in the side of the box.

I checked the fit of the spigot in the back of the box, the pivot that the box rotates on to set the angle or otherwise of the head. I can think of a couple of workshop expressions that would describe the fit, I'll call it "slack".

This, I think, is typical of the poor design of these far eastern machines, poorly proportioned. This spigot needs to be a lot longer, rather than ~12mm, 50mm+ would be much better. On the short spigot the head, on releasing the clamping bolts, will tilt forward and, possible, jam, making adjustment difficult.

I reduced the clearance in the spigot to 0.05mm by mounting the Z axis sliding member on a face plate. Reduced the diameter by 6mm. Pressed a sleeve on and machined it to get the necessary clearance.

While on the faceplate l checked the parallelism of the z axis slide, spot on! More on this later.

I then reassembled the head on the machine, refitted the top of the box and motor. I scraped away the paint from where the three clamping bolts fit and made some thick washers. I modified the oil filler bolt so that there was no chance of anything finding its way in to the gearbox.

Next job was to remove the quill.

Next job on this project was to have a look at the work table and the saddle. All seemed okay. I used an angle grinder to cut some oil ways into the fixed slideways of the X and Y movements so as to distribute lubrication to where its needed. Also fitted some oil cups to make oiling easier.

Two features I noticed that, at first glance, looked good, were leadscrew backlash adjustment and ball thrust bearings for the leadscrews.

The backlash is adjusted by distorting the nut, not the best way of doing the job but better than nothing.

What was, I felt, unsatisfactory, were the thrust bearings. It was possible for both the fixed and rotating thrust washers to do the opposite to the intended. Also there was no means of adjusting the bearings so as to eliminate backlash. As built the guy who assembled the machine must have assembled the relevant parts on the machine then drilled through the "dial clutch" and hammered in a roll pin, presumably hoping for the best!. So far the worst bodgery on the machine. The micrometer dial was also a very poor fit.

To sort this out I discarded the thrust bearings and replaced with a deep groove ball race (6203). I bored a suitable hole in the leadscrew supports and fitted a small ring to clamp the bearing in place. Wanted to use circlips but not quite enough metal to allow me to do this.

The Y-axis leadscew is only supported by the nut and one support. The X-axis leadscrew is supported at both ends and the nut. I have arranged the thrust to be carried by the R/H bearing, the other just guides the leadscrew.

I made two new "dial clutches" from steel that are keyed on to the leadscrew and a much better fit on the dials. The order of assemlby on the leadscrew was support with bearing, a spacer, "dial clutch" handwheel all clamped in place with an M8 bolt threaded in to the end of the leadscrew.. This resulted in zero backlash other than the (minute) clearance in the bearing. The nut backlash adjusters could not be adjusted to eliminate backlash in the threads but quite close before causing the threads to stiffen.

Oil cups fitted for lubrication. I also arranged some pipe work to get oil into the X-axis leadscrew nut, the Y-axis is easy to get at, just lift the swarf gaurd.

The gibs needed some tidying up before assembly. No further problems found during assembly, the table movement feels nice now.

So far not a lot of work needed to bring the machine up to an acceptable condition. That was about to change..........

Out on the mountain bike this morning I found myself cycling around Plaum's pits in Swindon. This pit is a lake formed from old clay workings. Many years ago the lake was divided in to two, two thirds for fishing and bathing, the rest for model boats. Now just fishing and thriving as a habitat.

Alongside the lake there was a raised 3.5/5" gauge track where I had my first experience of driving a (model) loco.

I had a hunt through the undergrowth to see if any of the track remained, all I could find were a few concrete posts and a beam that supported the track.

The local model engineers now have an extensive track elsewhere in Swindon.

Got me thinking about the many happy times at that long gone track and the not so happy time when I went along to the local ME club meeting with a view to joining. I think I was about 15 years old. Asked someone about joining and was told to "get lost, we don't want your type here", I've toned down the actual wording, it was some very bad language that would make a 15 year old blush.

As I walked back to my bike a guy came up to me and apologised and told me of another local ME group that met in a local school, come along to that, a good bunch of blokes he said. I did and he was right. Made some good friends. Only two of us left now.

One guy who used to come along might be familiar to GWR enthusiasts, Ernie Nutty,a fascinating guy to chat to.

John

To continue, the base is now bolted down to the stand. I checked that doing this would not distort the base. The stiffness of the base overwhelmes that of the stand so all okay.

Now ready to look at the column. In my research in to these machine the column can cause consdireable grief due to it often not being vertical, anything up to 1mm error over the length of the column.

How important is it for the column to be truly vertical? With this type of machine the head is moved in to position, roughly. The accurate movement is then done with the quill. This, for me would be true for most jobs. Any job needing a Z movement greater than the quill range can be done by moving the column up/down the column. Knowing where the error is can be compensated for. Never the less, zero error would be better.

I checked the slideway for accuracy. I found with the tapered gib adjustment that it ran out of adjustment before a satisfactory fit was acheived. Easily sorted.

I sorted out the lubrication of the elevating gear, a couple of grease nipples to get grease in to the thrust bearing that takes the weight of the head and to lubricate the bevel gears sorted this out.

The hand crank to elevate the head was held on the it's shaft by a grubscrew bodging on to a flat on the shaft. I have keyed the crank on to the shaft and clamped everthing together with an axially positioned M8 bolt.

After some careful preparation pf the joint faces and removal of the paint/filler from the bolt seatings I reassembled. While doing this I speculated that rigidity would be greatly improved if the base and column were cast in one piece and could I do anything to improve rigidity in this area.

To this end I have fitted two lengths of M16 all-thread that further clamp the column down to the base. A thick steel plate on top of the column and another under the ribbing on the underside of the base. I tightened the nuts to somewhere around 230Nm (170 ft lbs), to load the column in compression.

Will this help, yes, but con't ask me how much!

The two legths of all-thread fitted snuggly either side of the Z axis leadscrew as the photo shows.

At this point I checked the vertical accuracy, slightly better than it was. I have decide not to spend too much time fretting over accuracy for the moment. To get a better picture of accuracy I'll waiting until the machine is substantially complete.

Something odd going on here. The previous post is now incomplete and a subsequent post has disappeared all together. Any idea as to what has happened?

Time to get started on checking and reassembling the machine.

The first task after dismantling the machine was to assemble the stand. A thin sheet metal box held together with a few nuts and bolts. My first thought was this is going to vibrate, it does. There is a small door on one side, for a coolant tank and pump, I believe. Not fitting a coolant system so I have cut out part of the front of the stand and fitted a shelf inside. This will create useful storage space.

I also raised the height of the stand with a couple of pieces of 4x4 timber for a more comfortable working height.

Lifting the base of the machine was a two man job as was upending it to remove the moulding sand still stuck to the casting. What must that do to the manufacturers machines?

Accuracy checks, two rollers in the dovetail and measured with a micrometer and the depth of the dovetail were good. I tidied up the slot for the Y axis nut passes through and went over all the machined surface to remove any burrs.

All the cast surfaces had been filled and painted, the filler often being of considerable thickness. This I removed from wherever a nut or bolt is located. Absolutely vital for a properly clamped joint.

Daggers, found that link while researching which machine to buy. Not impressed with it, doesn't seem to address the fundamental problems. I may well have missed the detail, the videos are far too long, hours of viewing there! Also some dubious practises going on, he's a little to fond of his hammer. There are better videos, one in particular discusses the "Optimum" version of the machine.

Taf, the one thing I wanted was to avoid a "mission" by buying new. No where near as much work to do as you, but its heading in to "mission" territory!

This thread has been inspired by Taf_Pembs Chester Super Lux thread . The Cormak Z7045 is a very similar machine to the Chester as are the offerings from Warco, Grizzly, Arc and several others. The main difference between these machines seems to be the claimed quality and therefore price.

Not wanting to hijack Tafs thread I’ll start a new thread outlining the problems I have found and how I’ve gone about sorting out the machine.

First some background. My first mill was a far eastern mill/drill sold under the “Union Jag” label, bought from LS Machine Tools in Leicester. I purchased it in the late 1970’s before the poor reputation (at that time) of far eastern machinery established itself. I got lucky though, a couple of minor problems easily sorted. The machine was versatile and, with careful use, reasonably accurate.

This machine was replaced with a Herbert 0V, a sturdy, accurate machine that has served me well for some 30 years. My only complaint was the lack of workspace on the machine. This being the reason for buying the Cormack.

So, after “due diligence” the order was placed then delivered a few weeks later.

I already had reservations about the fundamental accuracy of the machine so the first thing I did after dismantling the packaging was an accuracy check. One recurring criticism of this type of machine is the vertical column not being vertical. I measured an error of 0.03mm over 300mm in the Y direction. Nothing detectable in the X direction. Promising, I thought. Also not particularly important, its what the quill is doing that is more important. There I did find an error that may need correcting, more about this later.

The machine was still outside, but undercover. To move it in to the workshop I would need to dismantle it in to a two man lift. I planned to strip the machine anyway so as to be sure all was well. I wanted to make some modifications anyway, some essential and some ideas that had formed examining similar machines.

What I have done is not on the epic level of Taf_Pembs work, fortunately for me! What is readily apparent is the poor detail design, regardless of supplier.

To paraphrase a comment by someone else here, its like you are buying a potentially good machine but its going to take some work to get there.

So, as they say, watch this space.

John

Another thought on removing the excess clearance from the quill. Chrome plate the quill. A generous layer of decorative chrome might do it, If not then industrial chrome. Reduce the diameter of the quill, plate to oversize then grind to suit the hole. The rack and internal features can be masked so as not to alter its sizes.

This works very well on Bridgeport mills, among others.

As for costs, don't know. Probably not that expensive as its a common enough process these days.

Taf, hope the work on the mill is progressing well, keep the thread going, its interesting.

John

I'm pleased to see this thread get going again, I recently bought a very similar machine, Cormak ZX7045. I'm hoping Taf's solutions might help me sort it out.

Regarding the "sloppy" quill fit, my machine seems okay, a tiny bit of play with the quill almost out of its hole otherwise good. It occurred to me that a simpler solution too removing the play in the quill might be to machine a slit in to the housing and fit a bolt (or two) to close up the unwanted clearance?

I've seen this technique used on older industrial machines, probably as a means of compensating for wear rather than achieving the initial fit?

I have found a number of problems with the Cormak mill so will start a new thread rather than highjack Taf's thread.

John

I now have the VFD wired up and working as I want. One thing though, I needed to use latching rather than the momentary switches shown in the wiring diagram.

I found this out by experimenting as suggested, ultimately with permanent temporary(!) wiring to verify all was well with the VFD using latching switches.

Any thoughts on this?

I've looked at several VFD manfacturers installation instruction and have not come across another VFD that uses momentary switches (jog function excepted). Also no mention of shielding cabling to avoid stray signals in the manual, did that anyway, other maunfacturers always mention it.

One final question, would it be possible to fit an emergency stop, Normally closed, latching. to the GND feed to the remote switches?

John

Thanks for the replies. I still have the motor temporarily connected to the VFD so was about to do as Martin C suggested then the reply from Peter S appears confirming that the switches are momentary.

I have also found another forum thread about this particular VFD (via a google search). This thread has a useful list of parameter settings for remote operation.

I'm not ready to install the motor and VFD just yet, but when I am I'm sure there will be more question.

Again, thanks for the help and guidance.

John

Thanks all for the replies. Martin C, thats the one, the manual seems to explain the settings for remote control.

The one thing I am not sure of is the swithces to (externally) control the device. As drawn in the circuit diagram they are momentary. Is that intentional or just poor interpretation of wiring diagram standards?

My thoughts are that these should be latching switches so as to provide a path for the selected parameter as other VFDs do.

John

Photo I forgot to post!

In a prevous thread I asked about matching a VFD to a motor. I have now run the motor (3ph) from a VFD (240v). All is well, the motor respond to the VFD inputs.

I want to arrange a remote (from the VFD) control. The photo shows the wiring connections for doing this. Stop/start and forward/reverse with an emergency stop if possible

I have some questions. Looking at the wiring diagram, can I have a single press button switch to stop/start before the forward/reverse switch, this being a toggle switch, on-off-on? That is to say select for/rev then switch on/off from a switch fitted before those two switches?

For an emergency stop switch would it be okay to fit a normally closed stop switch (big red button!) before the stop/start in the previous paragraphs arrangement?

Would I be correct in assuming that the switches shown in the diagram are latching, not momentary?

John

Lathejack, thanks for the hint, didn't work for me but google found it!

I've read through Taf's description, some good stuff. The one thing I will (strongly) disagree with is the use of epoxy to true-up the vertical column. In terms of rigidity (and therefore accuracy), metal to metal joint is absolutely essential. Introducing epoxy, shims or jacking screws isn't going to do much for rigidtiy. The column needs to be remachined. In Tafs case I see he has a largish lathe (Colchester Triumph?), how about clamping the column to the cross-slide and fly cutting its base?

My first checks of accuracy with my machine suggest the column is vertical so, hopefully won't need to do this.

Is Taf still out there? Would like to know how his rebuild if going

Lathejack, do you have a link to Taf_Pembs thread?

Surprised at the lack of comments, especially as this type/style of machine seems to be quite popular and available from most of the major ME tooling suppliers.

My first milling machine was the ubiquitous Taiwanese mill/drill, bought in the late 1970's. The very poor reputation hadn't been established at that point, fortunately I seemed to have got away with it. A couple of faults easily rectified, this machine gave me some 20 years of good service.

After that my experience of far-eastern machine tools was helping others sort out problems, repair and improve there machines. Most of the problems were due to poor design and inaccurate manufacture. They still seem to suffer the same poor detail design as they always did. Fundamentally, these machines, in general, seem to me to be okay, a good starting point to build up a useful machine.

That last point is why I started this thread, surely there are those here that have done work on there mills of this style to adress problems and improve?

I've looked on Youtube, lots there. One channel runs in to several hours of viewing but doesn't really address any problems, apart from a few obvious. I thought it would be useful for guidance on dismantling, unfortunately no. Also some rather dubious advice and techniques shown.

Interesting video on a powered quill feed, will revisit that on in the future.

So, anyone?

I've just taken delivery of a new milling machine, a Cormak ZX7045. The same machine, more or less, seems to be available from many different suppliers. I chose this particular one because price was good and reviews of the machine and UK supplier were also good. Was also looking for a machine with a larger workspace than my existing mill (Herbert 0V) but not too big a footprint.

Anyone know of any problems with these machines, useful modifications and improvements?

John