Member postings for Graham Meek

Contacting Holz & Hobby to ask about the materials used is never going to get a response. They are just a spares outlet for Emco machines.

If you need detailed information then you need to contact the Emco Technical Dept. However given the age of the machine the drawings for this I know are in storage and cannot be accessed by the Technical dept. I have tried recently.

The material will probably have a Werkstoff number with no direct comparison to UK specs and possibly SAE.

This material would need to have good cold working attributes as well as have a certain degree of work hardening. This last quality is one of the reasons to go down the Thread Rolling route as the thread form will be stronger and harder than the parent metal. It is however not the only reason to Thread Roll. This is another cost consideration which is settled at the design stage, by the Designer, not the Accountant.

Designers are constantly searching for the most economic methods of manufacture. Making things of Cast Iron is all well and good but this has its drawbacks when the section of the material gets as thin as the Carriage on the Unimat 3. Using Cast Iron here would probably mean using the Shell Casting Technique to get consistent results, an expense in itself. Sand casting would probably need more material and require machined datums later to hold the part, another additional cost factor. Both methods would also require a Heat Treatment process to remove any hard spots due to one part cooling quicker than another. This is an additional cost and we have yet to start machining. Contraction of Cast Iron is greater than that of Zamak, (to give it its proper name), thus the part would need to be cast larger than required. The weight of the Cast Iron is another factor which needs to be taken into account by the Designer, when it comes to dispatching 1000's of the finished item all around the world. Those extra Schillings for carriage would need to be taken into consideration when the initial cost of the machine was settled. Which is usually before pencil is put to paper.

I dread to think of the cost of machining this part from solid Cast Iron and any designer worth his salt would not consider this on a mass produced part. The Unimat 3 predecessor the SL sold over 300,000 units and we are not taking into account the copies made around the world.

A comparison of Zamak against Cast Iron shows very little difference in the mechanical properties. It has slightly better damping qualities which is good for such a small machine. I would also suspect the tensile properties would be greater.

As regards the short comings of this machine I don't see any. The only limiting factor I see with this machine is my imaginative use of the machine.

Just to correct one point. I have only recently returned to my Unimat 3 following the donation of a much modified/abused and worn out donor machine. Thus I did not use it to earn my income.

The Compact 5 I have, has been with me a number of years and complimented my Emco Maximat Super 11, Emco F3 and Emco FB2. These last 3 machines are all with new owners.

Emco were not the only machine tool manufacturer to use Zamak, not wanting to agitate the owners of these machines I will not mention these manufacturers.

I trust you will take this resume of Engineering Design in the spirit of learning something new about how Designers reach the end product.

Regards

Gray,

Edited By Graham Meek on 01/07/2023 11:54:25

I had one of the first U3's in 1976. As far as I can remember the U3 continued in production until the introduction of the U4 1997?? which marked the 50th anniversary of the Emco-Unimat. This was just before the Millenium edition, I also have a U4 leaflet with Pro Machine Tools email address on so that has got to be quite recent, 2002??.

Original U3 parts can still be had at Holz & Hobby, Austria. (As posted previously). This includes a complete carriage assembly.

The bearing you are saying is steel should be a Sintered bearing, which may appear to look like steel but it is definitely not. I cleaned up the face of the one in my U3 during restoration. I took off barely 0.1 mm and the material came off exactly the same as machining Sintered Bronze or an Oilite bearing. Perhaps some previous owner thought his modification of a steel bush was better? Sadly we will never know.

As a time served Toolmaker some of the YouTube offerings fill me with horror from an engineering viewpoint. Just because something is on there does not mean it is good. Making the modification is up to the individual. If that person is unsure then it pays to come to a Forum like this where countless years of knowledge, and learning by making similar mistakes can be given on the subject. It is after all free advice, but like all advice it can be ignored.

Lastly for quite a number of years during my 45 year career I earned my living using Emco machines. Not once did those machines let me down. Nor did I have a single job returned as being incorrect. The customers by the way ranged from Aerospace, Motorsport, Optical through to Surgical aids. That does not include the countless Myford Super 7 Handwheel dials I supplied to Neil Hemingway. The users of these may well be reading this.

Emco did after all give us the first mass produced Bench top CNC and PC machines, they were, as always ahead of the game.

Regards

Gray,

Edited By Graham Meek on 30/06/2023 11:45:10

Hi David,

I my apologies for not replying sooner. I have been in the middle of a Broadband upgrade that did not go too smoothly.

I take it this is the tailstock base you are referring to.

This was a salvage scheme done many years ago when I first had this machine. This was a tailstock from a donor machine. The original tailstock was out and rocked about on the bedways. The salvage of this tailstock on my Proxxon mill appears earlier in this post.

The Donor tailstock body was modified because the tailstock barrel was running out towards the back of the machine. Plus it was also dipping down towards the bedways.

I have been intending to draw this up and write an article on how to do it. The problem there is it may be some months before the article will get published. This modification is not for the faint hearted it requires a good deal of patience to achieve the desired effect. It does combine an adjustment to ensure the tailstock centre-line is coincidental with lathe spindle.

If you will bear with me and maybe give me a nudge via a PM in about a months time I will see what I can do.

Regards

Gray,

Edited By Graham Meek on 29/06/2023 15:38:54

Hi Jason,

A good move with the counterbore.

Regards

Gray,

The standard design has lasted 40+ years without modification. It is clear there are some issues with "backlash" and normal wear. Inserting a thrust race at this point is an overkill given the cutting forces involved. Two 11 mm O/D 5mm I/D Ball races in a new Bearing Housing would be more than enough to cope with the forces involved. Provided they were not over tightened in the quest for zero back-lash.

There is a down side to such modifications. The leadscrew or feedscrew experiences a certain amount of drag from the original set up. Remove that drag and the feedscrew or leadscrew could move during the cutting operation due to vibrations.

Another thing to watch out for when purchasing non-original parts are the "Limits and Fits" in operation in the country of origin. The "New" replacement leadscrew could well be smaller than the original Emco one. It could also be larger which may mean it will not screw into the existing hole and there-in is another problem.

The M8 x 1 LH taps used by Emco might well be H6 tolerance, the far eastern manufacturer might use a H7 tap. In both cases the feedscrew would be rolled to match the tapped hole to maintain the correct "Fit". Or visa versa.

Regards

Gray,

Lightly skimming the end of the handwheel to get a flat surface would not have removed the entire graduations.

Removing the damaged M5 thread portion would have meant the end of the Leadscrew was now inside the handwheel.

Inserting an M5 Grub or Set screw into the M5 hole would have locked the the handwheel to the leadscrew, after most of the play had been removed from the assembly.

If the Grub or Set screw was sufficiently long enough an M5 nut on the outside would have further locked this setting permanently.

As stated previously this is a standard Emco adjustment.

Using this method and a replacement handwheel would not require a new leadscrew.

Incidentally both these items are regularly up for sale from various vendors. Plus original parts can still be had from Holz & Hobby. The newer handwheels with white graduations have a steel insert.

Regards

Gray,

Edited By Graham Meek on 28/06/2023 11:20:08

Moving the Leadscrew Bush to the right a little would have removed any fouling problems as regards the handwheel rubbing the Bed. Rather than reduce the Handwheel a simple grubscrew inserted into the handwheel and impinging on the end of the M5 leadscrew thread would have locked the two together.

Emco used to use this method of locking on the Emcomat 7, Compact 8, with an additional lock nut.

Regards

Gray,

You will probably find the HT lead needs to be pulled through rather than pushed. Some silicone grease would also prove helpful.

Regards

Gray,

What is the Wimbledon Tournament? Is it held on the common?

Regards

Gray,

Hi Michael,

You have captured in a nut shell the design criteria associated with the Emco Gib arrangement.

Regards

Gray,

Generally

Like Kiwi Bloke I think the current tipped Gib arrangement will need constant adjustment. Line contacts wear rapidly. If one takes a moment to consider the set-up which is shown in the above photograph. The only part in contact with the underside face of the Bed is the outer edge of the Brass Gib. I also fail to see how this arrangement is superior to a Gib which is firmly bolted down. As opposed to something which is standing on Stilts.

Perhaps this is why there been so many designs to improve this Gib set-up over the years.

The plastic Gibs of my Unimat show a distinct wear patch adjacent the hold down bolts which is in contact with the bedway face. This patch extends across the whole width of the contact face.

From what I can see in the above photographs there appears to be a ridge on the Vee-way which indicates excessive wear. Something I highlighted in the other post on this topic when I suggested "lifting" the Carriage to check for vertical play.

Regards

Gray,

In the opening post it is mentioned about shims to get tooling on centre height. I had for a number of years used a quick change system of my own making. It was hardened and ground. With various dedicated tools for screw cutting and parting off, with about 12 toolholders proper. Keeping things clean while working on brass proved to be real problem on one job. I decided to full fill a promise to GHT and make one of his 4 tool Turrets, but with a twist.

The twist is the tools are completely without packing. The top picture shows the slope on the tool bit. The centre height of the tool can be preset as the design of the tooling at that angle means the tools are on centre height with 6 mm projection from the toolholder.

You will also note the toolholder completely fills the tool slot in the Turret. Keeping out bits of swarf from the mounting faces is a thing of the past. Carbide Insert tooling is also made to be on centre height.

What was worked out on the Emco Maximat got used on the Compact 5 in reduced scale, but the principle is the same. The Compact 5 tooling can even be used on my Unimat 3 without alteration.

Thus I have interchangeable tooling at minimal cost and across two different lathes.

Regards

Gray,

Edited By Graham Meek on 19/06/2023 10:39:44

The OP says he uses Carbide inserts. There is no problem with this provided the insert radius is not too big. I only use 0.2 mm radius inserts on my Unimat. Using a 0.4 mm rad causes a lot of vibration and a poor finish.

The Compact 5 will tolerate the 0.4 mm radius with no problem. Having said that there is more contact area on the carriage. Plus the headstock bearings and spindle are more robust. It is all a question of rigidity with these small machines. The quality of the insert is another key player. They will seldom have as keen an edge as an HSS tool properly stoned.

The Unimat machine was designed in the early 1970's and it was designed around HSS tools. This was the tooling that Emco originally supplied. Emco did not start supplying Carbide inserts for the C5 until the 1990's.

Regards

Gray,

My Son-in-Law has a massive solar array on his roof. It stopped sending electricity to the Grid early in May. Apparently a component has failed. When he enquired last week he was told it would be 6 weeks to get the part. As they need to get the part from China. It seems a post on Facebook yesterday brought the delivery date forward to this morning. They are currently fitting the unit.

It seems the theory of a renewable energy is one thing but the practice is a different matter.

I don't think matters are helped by the UK taxation no longer giving companies tax relief for their stock. It is simple really no tax relief, no stock.

Of course there is no compensation for the lost energy production. There is also the added insult that even though the energy prices have risen dramatically in recent months. The amount he receives per unit for his electricity has stayed at a pittance.

This reminds me of the saga about "a Horseshoe Nail"

Regards

Gray,

Hi Ady,

The ones Guy was talking about were out in the North Sea. I not sure Planning permission applies out there, but I might be wrong?

Regards

Gray,

Did anyone follow the Guy Martin TV series about Electricity Generation in the UK?

It was a very informative, especially the bit where we cannot use all the Wind Farm energy because the Grid would melt. Thus we are paying for them not to generate, as this is cheaper than renewing the Grid. Yet they are still planning to build even bigger wind farms.

The burying of the old Wind Turbines was another big No No in my book. Apparently the newer ones are degradable.

An approach on one of the Scottish Isles is the way to go. Use excess wind generation to go into storage batteries and Hydrogen generation, the latter is later used to generate electricity for use on the Island.

All in all a very good series.

Regards

Gray,

The Plastic Gibs are intended to sit slightly lower than the mating face of the bedway. When tightened they are pulled down slightly, while the free end bears against the bedway. Before I machine the U3 carriage to remove wear. I checked the step between and unworn part of the carriage working face and the Gib Mounting Face. This dimension was 0.03-0.05 mm smaller than the thickness of the rear bedway.

When I re-machined the working faces I replicated this dimension. By taking some material off the Gib mounting face. Parting off 12 mm Mild Steel on this lathe is no problem as long as the carriage clamp is on.

Thus the first check would be to measure the gap when the Gibs are tightened in situ on the carriage and the thickness of the rear bedway. If the Gap is larger it will need attention, if it is the same or smaller, then leave well enough alone.

A lot depends on how fine the glass fibres are chopped up. I tend to think of this material in the same way as a hand scraped surface. The high spots left by the scraping process are the the exposed glass fibres. Around these fibres small quantities of oil accumulates just as with the scraping. However given the colour of the material I would not be surprised if it was not already oil-impregnated. Thus it would be to a certain extent self lubricating.

Are you using HSS tools or Carbide inserts?

Regards

Gray,

PS was typing this as Ian's reply came in.

The rear Gib Plate on my Emco Maximat Super 11 was made of the same material. This lathe was 36 years old when I let it go this time last year. In all that time I only ever adjusted that plate once. I know a lot of potential buyers were put off by the use of plastic on this particular lathe, but that machine never once let me down and was still capable of some very fine work when I reluctantly let it go.

There is very little load on these plates, they are there just to keep the play to a minimum and keep the parts together. The geometry of the bedways is such that all cutting forces are taken on the upper surfaces.

If you can vertically lift the carriage assembly away from the bedways then no amount of new Gibs will rectify this. It is time to either rework your existing carriage as I did, or obtain a new or good secondhand unit.

Regards

Gray,

My Unimat 3 restoration, (see my album), uses the same Gib strips that were originally fitted, but just turned over. I personally would not use Aluminium for this application. Brass would be my only substitute.

Rubbing the existing Glass filled Gibs on some Wet or Dry will also restore the surface.

For what it is worth, the Compact 5 uses exactly the same set-up as the Bedway profile is the same on both machines.

Regards

Gray,

Edited By Graham Meek on 10/06/2023 11:07:35

Hi Clive,

I had missed the wheel dressing technique from my notes. It is something which I have done automatically in my profession, but had totally forgot about. Thanks for bringing it up.

The larger Lumsden grinders, which work on the same principle have a powered slide which dresses the face of the wheel, or wheel segments concave. It achieves exactly the same as you suggest, but it is quicker to do.

Regards

Gray,

Your error over 25 mm or 1" will be so small as not worth worrying about.

Your mag chuck may well be distorting the work if it is thin. This is what I was hinting at in my earlier post. Old feeler gauges make good packing when placing work onto the Mag chuck, before engaging the magnets.

The Mag chuck should from time to time be reground, but be sure all other sources of error are eliminated first.

Wear very often takes place in the centre of the table. It is where most people tend to place the work. Operators of Surface grinders will often place parts all over the table to minimize wear and save on table regrinds.

Strips of thick rubber with an aluminium backed edge. Rather like a Tenon saw, make good cleaning aids for the table. To remove dust and coolant, but nothing beats the palm of your hand afterwards.

Regards,

T'other Gray,

Edited By Graham Meek on 03/06/2023 11:29:48

If the Wheel head is not dead square it will grind a hollow. This may be only very slight, and may not be important for what you intend to use the machine for. However it is defeating the object as the machine can be made to cut perfectly, and any work coming off the machine is known to be flat. Provided the work has not been distorted during mounting it on the machine, that is.

Large ground steel tooling plates always showed signs of the back edge of the wheel cutting when I was in industry.

Regards

Gray,