Tuesday, November 21, 2017

Switcheroo, and Mulling over Milling

One of the minor issues with the Zimmermann PS ½ sanding machine was the on/off switch, which was on the verge of having its buttons fall out. I decided to take a look-see. Fortunately, a standard hydrant key, which I happened to have in my tool set, opens the electrical box:

Inside everything looked un-molested, which was good:

The switch itself was in good shape, and there was a brochure inside the box that was for the switch. It is a Siemen’s model, however not something they make these days. A little digging around and I found a NOS one in Texas, which I ordered as a back-up, for all of $22.50. Get ‘em while you can.

The part which had failed was just a piece of rubber in the external push button set. I love finding stuff which is actually user-serviceable - so rare these days. The escutcheon itself is aluminum, not plastic as one might otherwise expect:

The fact that the rubber was divided into two bits, and not that cleanly cut, told me that a past repair had replaced half of the rubber, or maybe it had been repaired twice for all I know. Seems like this is a wear item.

I used a caliper to determine the thickness of the rubber sheet required and ordered some up online. When it arrived, I trimmed a piece to shape and then cut a pair of holes in the rubber using a special bit intended for that task in my milling machine:

A minute or two later, the switch was all back together and in perfect working order:

It’s nice when there are straightforward tidy solutions to things that can be knocked off the tick list, at low to moderate cost, in a short time.

Not everything works this way however…

It’s been a little over 2 years since my 1971 Zimmermann FZ-5V pattern milling machine arrived from Germany. That arrival was detailed in a couple of posts back in October of 2015 (here and here). While at least one reader at the time was unclear on why a woodworker might want a pattern milling machine, and another asked why I had gone the semi- 'old 'arn’ route instead of a more modern portal CNC machine - perfectly legitimate and reasonable questions - I had a lot of ideas as to how I could put this machine to good use. I also knew very little about milling machines in general, so there has certainly been a learning curve, and that is a curve I continue to ascend.

In these past 2 years, I have found myself using the machine more and more and it has become an essential tool in my shop. While a lot of what it does can be replaced by any number of scratch-built jigs out of scrap wood, MDF, etc., I have come to enjoy that the machine has allowed me to reduce my consumption and use of MDF and reduce the time and energy formerly sucked up in the making of jigs and fixtures, which then tended to get stuck in a pile in the supposition of later usability (only to find that a year or three later I can barely remember what the jig was even used for - or forget that I had even made it only to discover such was the case after having made another one).

The milling machine allows me to work with higher precision - repeatable precision - and to do so with greater safety than before. For one thing, to be able to fix the material down and run a cutter over it in full view is wonderful! To be able to fasten the work down to a table which does not flex, and hold that work with assurance it will not move while being cut is simply a revelation. This, compared with what was the norm for me previously, namely, check it and check it again, and the scene of trying to tighten a fixture clamp only to watch the entire fixture bow in the process.

I’m sold on having a milling machine, and going forward it will be an important part of my shop, right up there with the planer and jointer. In fact the milling machine makes the jointing and dimensioning of small parts a breeze. To mention a couple of other plusses, I can also work aluminum and brass, which expands capabilities into making custom hardware and fixtures. I can mill steel and cast iron, which has allowed me to repair/alter some of my other woodworking machines.

There are some negatives to this machine, and I would be remiss if I did not mention them, and indeed some of these negatives have lead to certain difficulties:

- The machine is large and bulky, and weighs 2.5 tons. I was worried it might break the floor in my space, but that did not come to pass. It’s not a machine though, like a jointer or planer, which you can just stuff a pallet truck under and move around conveniently.

- it’s an old machine, and Zimmermann provides zero parts support. Zero technical support as well. Their business these days is making and selling large portal milling machines that weigh 20 tons or more, like this one from 2000 that forms its own room:

Even that is now old, a FZ30 model. Their new machines are FZ100 series or even later.

So 'little’ old machines like the one I have  from the distant past are simply unprofitable for them to pay attention to any longer I’m sure. Fortunately I have a parts manual and schematic diagrams for my machine, which helps somewhat.

- to repair certain things on a milling machine, you need a specialized machine. Care to guess what it is? Another milling machine. Toss in an engine lathe as well, and then a large granite inspection plate, and other inspection equipment. Do I have any of that? No.

- unique Zimmermann-made tool holders limit what I can do. I can make zero use of the high speed head on the machine, for example, because it has a weird tool holder that is not longer made by the company.

The age of the FZ-5V is starting to show in a bunch of ways:

1) It won’t hold oil in its ways, especially the rotary table, which loses oil in a matter of minutes. I gather that the seals are worn out. Fixing them is not a simple job though. Way oil is not cheap, and I’m tired of cleaning up the puddles of oil off the floor, and it has been like this since I got it.

2) the manual spindle brake has now worn out. It’s probably a simple affair similar to a drum brake on a car, however to access the brake itself requires a bunch of disassembly. Now that it is worn out, sometimes I have quite a hassle getting a tool holder out of the spindle.

3) the quill has slop which allows it to rotate a certain amount. No amount of axial rotation in the quill is in fact desirable in the least. This slop led to much frustration when using the right angle attachment on a previous job, and produced some ruined parts as a result. The quill is also sticky and does not plunge smoothly. The spindle lock works, but when clamped on it gets stuck and won’t release, requiring that it be taken apart. Fixing the cluster of quill-related issues involves disassembling the machine’s head. If that is going to happen, one may as well replace all the bearings and seals while one is at it.  It is likely a $5000 bill to deal with the quill issues.

4) the power drive of the rotary table failed last month while working on a wheelstock for a Chinese wheelbarrow. This outcome likely connects to the problem of the non-existent oil retention. Repair may involve making a new gear, however getting access to that gear will require extensive dismantling of the machine and the parts are really heavy. Plus I have no idea what I’m doing, but why should that stop me :^). At least the manual drive system for the rotary table still functions, but it is physically and mentally tiring to use if you have to employ it for any length of time.

5) when powering the table assembly up and down in 'z’ axis, there is a groaning noise during a portion of the travel. Not sure what is causing that, but it does not sound good and like other issue with the mill, extensive disassembly is required. If I am forced to take the saddle and the knee off, then I may as well replace bearings and seals while I am at it.

6) once in a blue moon, while using power feed to raise the table up, the electrical circuit sorta 'goes to sleep’ and the machine table keeps raising after I have let my finger off of the button. This requires a quick sprint over to the disconnect switch on the wall. Once power is back on, the problem goes away, and it happens so infrequently that it is difficult to diagnose. I’m always apprehensive when raising the table up as a result. The machine’s electrical system relies upon old ceramic fuses, and these are not so easy to source. If I were to disassemble the machine, then I would also likely be looking at going through all the electrical stuff as well.

The machine remains largely functional, but the problems described above have been coming one by one, and seemingly a little more frequent in occurrence with each passing month. It’s an old machine. I worry though about what the next thing will be, and whether it will cause a part to be ruined, or further damage to the machine, or leave me stranded in the middle of a work process.

If woodworking was my hobby only, and I felt like I could take the mill’s repair work on myself (which to a large extent I am confident that I can), and had some money to spend on it, then I might choose to take it all apart and repair and restore it over the course of several months. That’s not my situation though. I simply can’t devote the time to it, and I know that any decision to strip down the machine invites the 'tip of the iceberg’ effect in terms of what one might find that you really have to deal with once things are apart. Thus it is difficult to ascertain how much money it might cost to put the FZ-5V right.

I recently had a fellow from a spindle rebuilding company in New Hampshire pay a visit to my shop. The company, SPS Spindle, offers a site visit to price out repair work, saving one from the alternative, which is to take the machine apart and bring the parts to the company for inspection and pricing. Obviously, in assessing my machine, there are any number of unknowns, so the pricing is somewhat of a guess, but it looked like a rebuild of the spindle and quill on my machine, along with attending to the various other issue, including the tool holding problem, was going to be in the zone of $10,000.00.

Well, I have so far spent about the same money just purchasing and getting the machine into my shop, so the prospect of shelling out the same amount was not exactly mouth-watering. It’s not a crazy amount of money though, not in the world of large machines with spindles. The FZ-5V was selling for something like 50,000 € when it was last being made in the mid 1980’s. If it were on the market today, factoring in inflation, I would be looking at a purchase price for a new machine of 123,684.43 €, according to one online calculator I tried. Would I be in the market for a machine at that price point? No. Is a $10,000 repair on a machine which would cost 123,684.43 € otherwise reasonable? Sure it is.

I don’t get hung up on how much money has already gone into the machine, or let that guide any decision about what I should do now. I’ve spent enough time in the past dwelling on such ’sunk cost issues’ to have learned that it is not the most rational approach. When faced with the prospect that $10,000 might have to go into the FZ-5V at some point, I start thinking about whether $10,000 could be better spent perhaps. Yeah, I know, 'wise use of money’ and 'woodworking equipment’ is not a natural or entirely sensible combination in many people’s eyes. Maybe I should look at Bitcoin?

I asked myself if, at the end of the day, a $10,000 investment into that machine would result in all I ever wanted in that machine? Would it be my dream come true? No, in this case, it would not actually. The ergonomics of the FZ-5V are not the best, for one thing. I would like an even bigger work envelope, and have found turning hand wheels back and forth all day loses its charm rather quickly, as I find it hard on my rotator cuff muscles. A machine that uses a toggle switch, push button, or joystick to achieve the same motorized control of movement (like on my jointer or planer) would be preferable.

So, what are the options that loom large, besides repair?

1) Are their other machines with similar functionality and size? Well, yes…. Two similar sort of size pattern mills of which I’m aware are the Wadkin WS and the Oliver #102-103-104. Both machines are from the pre-WWII era. I’m not sure I want to step further back in time than what I have now, technology-wise, and I’ve been less than fully delighted with a past Oliver machine and a current Wadkin machine. The Wadkin uses a railway track on the floor for the main table, and this would not work so well with the wavy and movement-prone wooden floor in my space. The Oliver would be a challenge to get into the building, at 8’ of height, so some disassembly would be required. I doubt that either machine would be as precise as the Zimmermann, and the tooling would be of some older format, likely Morse taper #3 or #4, which is less desirable to me. The Oliver #103 does have 8 speeds, max rpm of 4100 and 6" of quill travel, a bigger work envelope with loads more x-travel, so it has attractions, despite my wariness of the brand.

2) Going to a bigger machine, with a Bokö milling machine, say. These are in the 4~8 ton range. I would be interested in this direction, but a bigger machine simple wouldn’t even fit through the door of the shop building, and I’m sure would be too much for the floor. At least there is parts support for Bokö however, and even a distributor in the US exists.

3) Go same again. There is a 1983 FZ-5V for sale in Germany, 12 years newer than the one I have. The machine reseller wants 6000€ for it, which is actually less than they bought it for, having had it on the market for a while now. Apparently it was not heavily used and does not leak oil, and to boot it has an additional motor fitted for powered y-travel, which would be nice. It uses a remote control panel on a swivel arm which improves the ergonomics. The electrical panel is more modern, with relays and a single circuit board. Without going to Germany to inspect in person, this is a risky purchase though, just like last time.

4) Go smaller. Zimmermann made a machine about half the size of mine, the FZ-1, which would be able to tackle 80% of what the larger machine can do, albeit at a significant reduction in work envelope:

5) Go modern with CNC. There are lots of options in this direction, ranging from machines way out of my price range to little gippers intended for pen turning and jeweler’s work. There is a DIY CNC scene, people welding up their own tables and buying components with which to build their own machines. However, most of what I have seen would appear to be designed more for production in volume than the type of work I do. I am not interested in programming just for the sake of drilling a few holes, or making a series of cuts on 2~4 parts. It doesn’t make sense, though the user-friendliness of these machines is improving from what I have heard. Many CNC machines are intended for sheet goods work and take up a lot of space, which I don’t have. There is likely a configurable solution, however it will require a fair bit of research yet.

6) Go to a metal working mill. With that, there is a reduced work envelope -  at least for the size of machine which can fit in my space - no rotary table with most machines (except as a small accessory which mounts to the main table) and much slower spindle speeds generally with machines built for cutting metal. There are high speed milling heads for some machines, and some come with really cool super versatile tables which rotate and tilt, like the Maho universal mills, and some, like Deckel mills, come with both horizontal and vertical spindle drives. A good machine though, is a chunk of change and is likely coming out of Europe, so this option is a well beyond my price range.

7) Go outside of the box with some sort of DIY fabrication to change things on the machine I have. I could, for instance, consider removing the head on my machine and fabricating a mount for an electrospindle which would solve quite a few problems. Higher speed, variable step-less speed control, built in motor braking, modern tool holding, etc.

I’m not really sure what to do at this point. There are options, including doing nothing. The machine will remain serviceable for a while longer, however I really have no idea how long I can rely upon it, so planning for what to do next is occupying my thoughts. It is tick-tocking its way toward becoming a 5500lb paperweight in my shop, and I feel I need to do something sooner rather than later.

Perhaps a reader out there has useful advice - if so, I’m all ears.

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