Member postings for Graham Meek

Further to your last set-up I have tried the same set-up on my FB2, which has a brand new spindle and angular contact bearings instead of the Ball races.

Using a clock similar to the one shown in the last video, I had 0.03 mm deviation but in the opposite sense. Using my Mitutoyo clock in exactly the same way I had 0.02 mm deviation, but again in the opposite sense.

During these test I had a DTI resting on the spindle nose flange. While this face is not ground after heat treatment of the spindle. I had a consistent 0.01 mm deflection which ever way the spindle was rotated.

The next test was to use a Dial Gauge or "Drop Clock" to check this out. This was set up in my boring head to get the ball stylus running absolutely true on the machine centre-line. With this test I had 0.005 mm variation during the two opposite rotations.

As a last check I used the Dial Gauge held in the Machine vice and indicating on the end of the Spindle. I had the same 0.01 mm deflection I had earlier irrespective of which way the spindle is rotated.

All test were carried out using a long Allen key in the draw bar socket.

One problem I have learnt over the years in my profession is that the lever type DTI can give two different readings when presented to the work in different directions. It is due most probably to the clock construction.

This I believe is what is at play here.

Lastly, while the Lever clock has a good range of adjustment on the stylus. Its accuracy as a measuring device is limited. Most Manufacturers used to stipulate a maximum angle either side of the centre-line, or in-line position, after which the scale on the dial was meaning less.

Regards

Gray,

I have the official Emco works drawings covering the spindle. Its component parts and the assembly of those parts.

The Spindles are graded into three different sizes. As an example Class 1 is 30.023, +0.003, -0.006 mm, the Class 3 spindle is 30.033, + 0.005, - 0.003 mm. Class 2 being in the middle with similar tolerances.

Each Spindle is matched to another specially prepared Needle Roller bearing, made by INA NK 30x20 P6/ H32+26. Hence this is why Emco only supplied this as an assembly. When trying recently to get one of these bearings it was impossible. In the end I managed to track down a Japanese bearing with an extra roller and better tolerances. It is possible to get a new spindle but the owner will need to Lap the diameter to suit his bearing.

The two Special Ball races, FAG 6005 C3.K3 VSPK 10 kp, are secured in the Quill with Loctite 601, so even if the Ring nut came undone the bearings would, should stay put.

The problem I have with the original set-up above was touched on by Andrew.

If the two planes of contact are at a slight angle and complimentary to one another. Then when the cutter is rotated the error would be evident and double the displacement, or inclination.

Similarly the Ball acting on this inclined plane, although it appears to give only point contact. It is in fact touching off to the one side. If that ball is also running out, or eccentric in the collet. Then the contact point will move around on the top of the ball, and will not be directly under the spindle as it is assumed.

Unfortunately straight cut gears transmit the drive to the Quill. The Helical gear is the input drive gear to the gearbox from the motor. Turning the Spindle against rotation does tend to cause this gear to lock-up. As the helical gear is trying to lift the Sliding Gear and its spindle. Any additional force being applied manually to the Spindle to overcome this would affect this set-up.

It is also assumed that there is no side play in the measuring device. Which would allow the top to tilt slightly. There has to be a clearance here for the device to register freely. The unit is after all designed only to set the cutter height in a CNC application and is being asked to do something it was not designed to do.

Regards

Gray,

The two matched deep groove ball bearing races were specially made for Emco. They have markings on to ensure that they are assembled correctly.

In the past I have replaced these with angular contact races, but with no real gain as regards machine performance.

Any preloading of these bearings can stall the machine on the highest speed.

The movement on the clock from applied external pressure is to be expected, this is a bench top milling machine remember.

Any checks for spindle play should be done with the clock fixed to the head of the machine, or with the Quill removed from the head, and held in the machine vice, with suitable protection. I doubt any play will be found.

There are a number of factors at play with this set up.

Is the top surface of the measuring device perfectly parallel to the table surface?

Is the end of the Cutter perfectly parallel to the table surface?

Is there any run-out on the collet?

All of these three defects can give spurious results.

Personally if I swing my clock over a 200 mm long parallel on the table, (tramming) and get zero deflection, then that is good enough for me.

Regards

Gray,

I have for a number of years had an Emco Compact 5. This will be the mainstay of the workshop along with a Proxxon mill, when the table turns up. If the sale of the Maximat Super 11 and the FB2 generate enough funds I might add the larger Proxxon lathe.

I have also been given a well worn Unimat 3 which has had a full restoration and can be found elsewhere on the Forum. (I still have to finish this electrically).

Recently I have been working on a design for a screwcutting clutch for the C5. Once you have had this facility it is hard to let go. This is now ready for manufacture, but it will have to wait for a short while.

A few further notes on how I go about grinding in the lathe might be handy for those wanting more info.

A rectangular tobacco tin partially filled with water is place under the grinding wheel. This is kept in place with an Eclipse Pot Magnet, placed inside the tin.

When dressing the wheel the grit goes into the tin, as well as the debris from grinding. Dressing the wheel should not take more than 0.05 to 0.1 mm to clean up the wheel, 0.002 to 0.004" ref.  While grinding I present a cotton pad to the rear of the work. It is made in the same fashion as a French Polishers Rubber. This is soaked in water but not dripping in water. The action of this pad is to trap particles of grit or metal debris which would get imbedded in the wheel and ruin the work. Plus the mass of the pad allows a certain amount of cooling to take place.

The spindle is run in reverse for external grinding and forwards for internal grinding.

When doing internal grinding, like the new ER Spindle for the Proxxon mill, (listed elsewhere & in my album). I usually squirt a drop of water into the hole, but not a lot. This keeps the wheel free of debris and cools the work. Again any debris drips into the tobacco tin.

A toolpost grinder is on the list of items to make for the C5.

Regards

Gray,

Edited By Graham Meek on 25/01/2022 11:33:39

Like the first Volume of the Projects Book, that decision lies firmly with TEE Publishing. It was only ever called Vol 1 for a means of having other volumes by other authors if I remember correctly.

This year marks my 11th year of writing and with 50 + articles already done. It is also the year that the Emco machines are going to be retired. It may well be that I shall retire from writing too, as yet I have not made up my mind. While I do have several items still to write about, time is in short supply these days. Plans are afoot to down size to smaller machines and I want to concentrate on getting these to a stage I am happy with. Maybe after then I might pick up the pen again.

If you desperately want to know about a Vol 2 I would suggest you contact TEE.

Regards

Gray,

Hi Andrew,

The grinding is not required, a good finished turned item will work just as well. I grind because I have a toolpost grinder and I can finish multiple parts quickly. It is one of the traits of being a Toolmaker by profession.

As regards using a toolpost grinder, provided the ways are covered, ( I use a piece of Denim, dark blue up, that way this side always gets the dirt), I have had no problems with my 36 year old Maximat form using a toolpost grinder. It is a genuine Emco product.

Regards

Gray,

I have had a chance to make a start on the new spindle for the Proxxon Milling Head which is shown below.

The front bearing has been increased to 15 mm diameter to make the spindle a bit more rigid without having to modify the quill housing. As this bearing is 1 mm thinner than the original a 1 mm spacer shim is required. While the bearing is rated slightly less than the original I am prepared to live with this. The manufacturer has probably over specified the bearing anyway.

All I need now are the ER 20 collets to go with the spindle. As regards the associated tooling for this spindle that will now have to wait for a few weeks.

Regards

Gray,

I have tried un-successfully to obtain an ER 20 Spindle from Proxxon, so I am in the process of designing one.

In addition to the collets, I intend to fit a bayonet clamping ring to the ER 20 fitting. To hold such things as my small boring head, milling arbor, shell mills and drill chuck. All these items will use the 16 degree collet taper for location.

I will post some more details in due course, but with an operation pending at the end of the month, please bear with me as regards to the time frame.

I would also like to make a dedicated machine vice for the mill, similar in design to that used on my Emco FB2. While I have the compound table on order, (3 weeks delivery date). I would like to get on with this design in the meanwhile.

Can I impose on owners of this milling machine, to supply me with a couple of dimensions?

I would like to know, the dimensions of the spindle centre-line with reference to the back face of the milling table.

When the Y-axis is fully in, and fully out.

Thanks

Gray,

Rotational deflection of the Column is resisted by the Guide Bar set into the Column. In order to allow the Head to slide up and down there needs to be a small clearance. If this clearance were 0.001mm then the deflection at the clock just taking up the clearance would be 0.01mm as the lever ration is a factor of 10.

I doubt the slide would move with such a small clearance, it would be more likely to be 0.01mm to start with, which would give a deflection of 0.1mm at the clock. (Oil films do need a space to work in)

As regards adjustment of these surfaces there is only one way to do this, and it is not, with the feedscrew attached.

The head needs to be removed from the Column. It will rest happily on the table with a couple of parallels and no heavy lifting is involved. As the separation movements can be controlled by the table feedscrews.

The Column is removed from the Casting Socket and the above mentioned Gib slackened. My bench vice with suitable protection pieces will just grip the Column. Adjustment can then be made to the Slider to Column interface. It should glide effortlessly from one end to the other with a faint hint of resistance, or drag, but no play.

I find this adjustment gives a better result with dry contact surfaces. Oil is only applied once the slider to column is adjusted.

The Gib is then adjusted such that it removes any rotational movement but does not interfere with the initial adjustment.

Do this the other way around and expect trouble.

Having the above adjustments too tight will just prematurely wear the feed-nut, (expensive), and the handwheel bearings.

Back to the original plot,

The Vice set-up shown in the picture is not what I would do. It is probably done to maximise the amount of slideway contact, but the clamping arrangement is nowhere near where the cutting is taking place. It induces another Lever moment.

The main force resisting cutting, when cutting with the side of the endmill in the Y-Axis, will be along the Y-Axis. The reaction to this force will tend to deflect the head upwards, if it can. A small Resultant reaction force will be trying to deflect the milling head to the right in the set-up shown, but will also be trying to lift the job, the vice, the table and the Y-Axis slideway. (Helix angle on the cutter).

This is why manufacturers of our range of machine tools always tell us to lock those slideways not in use.

Regards

Gray,

Edited By Graham Meek on 10/01/2022 12:12:28

I used to suffer with this problem many years ago when I first had the first of my FB 2's.

The finish using the side of the endmill in the X-Axis was always perfect. However when using the same cutter on the Y-Axis it was a different story.

Holding the machined face at different angles to catch the light would show striations along the face. Aluminium was particularly bad at this, but steel being better.

First thoughts were the Gib being loose on the Y-Axis, but this adjustment met with my satisfaction.

I finally traced the problem to the actual cutters being used. These were made by Osborn, so a good make. However the cutting angle on the side of the Osborn cutter was 5 degrees. Changing this to 7 degrees totally removed the problem. The cutters also cut with less effort. The downside is the cutter life is less when compared to the 5 degree. As I sharpen my own cutters this is not a problem for me.

I have found the Helix angle of the cutter also influences this problem. Some straight flute cutters I have do not show any signs of this problem.

Regards

Gray,

To Friends old, and new, A Happy, Peaceful Christmas and Good Health in the New Year,

also take time out to remember those who have to work today,

Best wishes

Gray,

Hi Paul,

I have sent you a PM, which might be of interest to you.

Regards

Gray,

Hi Paul,

Glad to hear you are sorted, and I hope you have many happy hours with your Maximat. Mine is 35 years old this year and shows no signs of wear, despite earning my living for a good number of those years.

Regards

Gray,

I do have a spare manual, but pages 23 to 30 are missing. I can scan these and print them out if you do want the manual?

Regards

Gray,

I think I have a spare manual that will be FOC, but plus postage, I will check and get back to you this morning.

Regards

Gray,

This view shows the two self tapping screws and the shape of the Delrin filler piece better. Note the two shadow lines to simulate the original catch.

(Clicking on the image makes things clearer)

Regards

Gray,

Progress on the restoration has slowed over recent weeks. Mainly due to the effects of my booster jab on my illness.

Father Christmas did get his dates mixed up however in that I had an early Christmas present from my Daughter in the form of the Milling attachment for the the Unimat.

You will see from the above Photograph that the lathe is now sporting some new Handwheels, which have been made in-house with adjustable dials.

I wanted to keep the Black Handwheel theme going, so the main part of the handwheel was made from Delrin. The small piece of Silicone O-ring acts as a spring to provide friction on the dial by displacing the Delrin ear on the handwheel.

The ear can be seen more clearly in this shot, as well as where the small piece of silicone goes.

This shows the dial in-situ on the longitudinal feed, or leadscrew.

Originally I made one new Idler pulley for the Milling attachment and two motor pulleys, but yesterday I noticed the original plastic mandrel pulley was running out by a mile. When received this lathe was fitted with some vacuum cleaner drive belts. These had been on the machine for sometime while in storage and had given the pulley a permanent set. A new aluminium pulley was duly made.

The original integral catches on each guard had been broken at some stage. A piece of Delrin was machined to fit the vacant space and four small magnets were pressed in to keep the guard closed in use.

I tried to mimic the original catch as best I could. The small protrusion makes getting the guard open very easy. The replacement piece is held in lace by two small self tapping screws.

My next task is to make the base board to house the electrics for the motors.

Regards

Gray,

Edited By Graham Meek on 04/12/2021 19:20:57

Edited By Graham Meek on 04/12/2021 19:21:58

I would have thought they knew who you are, especially if you tax your vehicle with them.

However it does not bode well for me as I will have to jump through the same hoops next May. For a start I do not have a valid passport. Then there is the paper driving license that I hold, they have probably not even logged those numbers into the computer.

Regards

Gray,

I had a similar problem when I first owned a Unimat. I traced it in the end to the armature oscillating in the bearings. An extra shim washer was fitted and that cured the problem.

An easy way to check if this is the cause is to remove the motor pulley and apply end pressure to the armature while the motor is running. If the noise disappears then I would say you have found the problem. It should not require excessive force for this test and a scrap piece of plastic is useful to apply the pressure, as this will not damage the end of the shaft.

Regards

Gray,

I have had a problem with getting my prescriptions since we have had a new practice.

I have to adjust my Steroids at short notice, so there is no chance for a standard repeat prescription set-up. In the past I have requested my needs via Boots Pharmacy with no problems. A few months back I requested some Gastric coated 1mg tablets.

Went to collect, and no tablets. Calling the Surgery they were telling me I had enough Steroids to go on with, (all 5mg's), also that the 1mg were not manufactured in Gastric coated. Boots were also telling me that they did not make them. On the NICE site it said they did supply them. One of the suppliers was Alliance, who are owned by Boots, so an email to the CEO resulted in the tablets being available at the Pharmacy within two days.

However the prescription did not get through to Boots for another week, and that was only after I raised the matter as a compliant with the surgery. A problem on the "Smart Card" was duly held responsible by the surgery, along with profuse apologies, but it also transpired following a complaint to the Care Commission that they had stopped the supply of the 1mg Gastric coated in Gloucestershire.

Again this week we had the same scenario as the opening post. Request to the Pharmacy never made it to the surgery, apparently. An email to the Practice manager did, and my tablets were picked up yesterday.

Personally I would trust my Pharmacy 100%, my Surgery, well that is a different matter. After 10 years working for the NHS, I only converse with the Surgery after this fiasco via email, they are not so keen to handle the truth unwisely, when it has to be written down.

Regards

Gray,