Emco Compact 5 Modifications

[Colin CreedParticipant @colincreed93792]

Here’s that YouTube post I’d made mention of previously about the making of a “cut knurling tool”.

https://youtu.be/vj8pp3YJijg?si=JDKJVENAkE8kAHI1

[Graham MeekParticipant @grahammeek88282]

When using normal form knurling tools it is customary to be working at slow speeds. Some of the knurls above were produced at 300-500 RPM. The higher speed tends to get rid of the chips better. One Beauty of Jacques design is the simplicity in setting up. Admittedly it does take two passes when doing a diamond knurl, but given the results it is well worth the extra pass.

I have been having a go at putting John’s advice into practice when using the Helical knurling wheel to produce a straight knurl, and I must say it makes a difference. I have also rigged up a compressed air stream across the work and this gives a further improvement. When I get a chance I will take some photos of the results.

Regards

Gray,

[Graham MeekParticipant @grahammeek88282]

John has just completed the 3D view of my diminutive Cut Knurling tool.

This shows the construction details very well, especially the fine adjustment, (the small block held by two cap screws), to correct the helical spiral some knurls produce because they are not at the correct angle. Note also the spring loaded plunger to keep the index plate in place when turning the head from one position to another.

Regards

Gray,

[Colin CreedParticipant @colincreed93792]

Hi Graham,

 

Thanks for the update on this & to John for his 3D view.

I’m keen to know more about the pro’s & con’s to making this tool.

 

regards Colin

[Graham MeekParticipant @grahammeek88282]

Hi Colin,

The Cut knurling process is a lot kinder to the machine than the Forming process of more conventional Knurling techniques. The large pattern of the Diamond knurling shown above would be nigh on impossible to do on the C5, using the Forming process. Yet the C5 cut this knurl with no trouble at all using this tool.

Regards

Gray,

[Graham MeekParticipant @grahammeek88282]

Just a few photographs to show the latest additions to the C5.

This next view shows the drive cover removed and the Proxxon Collet chuck adaptor fitted.

The two spanners are required to change the various Arbors. The Hexagon can just be made out behind the timing belt. The tapers ensure complete repeatability as regards concentricity and run-out once a wheel has been dressed.

The next photograph shows the unit fitted to the lathe.

It is not the best picture as the workshop space means I cannot get a better shot.

There is plenty of room between the tailstock body and the grinder body as can be seen above.

The next item is thanks to John Slater who provided the No2 Morse Taper blank. Those of you who have tried using a No 2 Morse Taper Collet in the C5 will know the collet disappears into the Mandrel socket by some considerable margin. This is not handy if the work to be machined is only just protruding beyond the collet. This attachment overcomes this problem.

There are a couple of other items I intend to add later.

Regards

Gray,

[Colin CreedParticipant @colincreed93792]

Hi Graham,

Nicely thought out & it looks to be a terrific addition for your C5 Lathe.

regards Colin

[Graham MeekParticipant @grahammeek88282]

Hi Colin,

Thanks for the kind words. This project seems to have dragged on a bit, just like our winter, but I managed to complete it. I have a job coming up for the Proxxon Mill that will put the grinder through its paces.

Regards

Gray,

As promised there are a few more photos to share,

This is the view from the operators position.

The next item has been waiting to be made for some while. It is taken from an article on U3 & C5 Accessories, by Graham Nickson.

I have made it slightly thicker than the the original drawing as I wanted to use standard cap screws to attach the adaptor, instead of the countersunk screws shown on the drawing. I should point out that this article contains a Drawing Error. The Pitch Circle Diameter (PCD) for the attachment screws is shown at 30 mm. This should be 29 mm PCD. It may well be the information supplied by Graham was correct but it may have been regarded as the wrong dimension by the magazine, alas we shall never know.

This next item was originally intended to fit the U3.

When I first tried to fit this 70 mm Soba chuck to the U3 it fouled the headstock casting. The recess for the mounting face was too deep. A small skim off the offending face soon rectified this. When I stood back I felt the chuck looked hideous. Upon further investigation the scroll inner diameter would allow the 29 mm PCD of the C5 mounting screws to pass through. With the aid of a location plate to register on the 40 mm C5 Mandrel diameter and some M5 Allen grubscrews for radial adjustment I now have a chuck with “Griptru” characteristics. Which is very helpful in its new role on the Dividing attachment.

Regards

Gray,

[Graham MeekParticipant @grahammeek88282]

John Slater has been busy making some more 3D images of the Tool-post Grinder. This gives an idea of what is going on inside the unit.

They say a good picture saves a thousand words.

 

Regards

Gray,

[Graham MeekParticipant @grahammeek88282]

It is now twenty years since I purchased the Compact 5. In those twenty years I have been trying to acquire the 80 mm 3 Jaw High Precision chuck with the two sets of jaws, (V3U 176). For most of the time over the intervening years when these chucks appear on Ebay they are short of the set of reversed jaws.

When one did finally appear complete it was in the USA and the Vendor would not ship to the UK. However my Son-in-law has friends in the USA with his job with Microsoft and we eventually took delivery of the chuck about 2 weeks ago.

The elation of finally getting the chuck was dampened somewhat when the chuck revealed a 5 mm TIR, yes that is Five millimetres. Sending the chuck back via the protracted route was not really an option so the only thing was to sort it out.

 

This first photograph shows it had received a hard life given the physical damage. What is not so apparent is why there is 0 to -0.3 deviation on the tenons in No1 Jaw location.

This second photograph starts to show the bigger picture. The two tenons are cracked and between the two felt tip lines can be made out a hairline crack which runs through the part.

It was nearly as bad on No 2 Jaw location and again another hair line crack through the part.

After 16 hours of work a new part had been made using the C5 and the Proxxon Mill. It may be of interest that the 90 mm cast iron blank that I started with lost almost two thirds of its original 993g in to swarf tray.

A drawing was made from the existing part and cross checked with the 4 Jaw self centring chuck (V3U 178) that I have. One problem was going to be checking the 36.00 mm diameter which is recessed in the chuck body. The size of this diameter is critical as via the scroll bore this locates the two haves of the chuck. To check this accurately really required a Disc Micrometer. However buying one just to check one dimension was never going to be an option. Talking it over with John Slater we came up with a solution.

Unfortunately for now the photograph for that will have to wait.

Regards

Gray,

 

[Colin CreedParticipant @colincreed93792]

Hi Graham,

That’s quite the “journey” both physically & emotionally, as well as mentally trying to wrestle out a viable solution…glad to hear there’s a “happy ending”.

I’m looking forward to hearing more about it.

regards Colin

[Graham MeekParticipant @grahammeek88282]

Hi Colin,

You are right about it being an emotional and physical trial. On the penultimate operation, producing the square slot beneath the new tenon. I had started cutting and nearly scrapped the part as I realised I had not locked the Quill. The quill fine down feed handle had started to counter rotate due to the vibration as it entered the void where the scroll sits. The cutter had started to rise. Putting a slight down feed on the handwheel and gently winding the X axis out of the cut I managed to do no further damage. Resetting the cutter and continuing the cut I could see a faint witness of the cutter in the underside of the tenon.

After completing the other two jaw locations I raised the cutter by 0.05 mm and passed back through the first location and luckily it cleaned up. Repeating this operation on the remaining other two locations completed this clean-up. All that remained was to off-set the cutter to establish the correct width on each location.

The final operation was to establish the thickness of the tenon and the correct width for the jaw location. I can assure you that after this I was feeling extremely tired from the concentration.

Back to the plot,

 

This attachment was kept as simple as possible. the only thing that required making was the L-shaped Brass block. It was envisaged during the discussions with John that the clock could be swung across the diameter while urging the Brass block against the diameter. In use it performed exactly as we had envisaged and made a very difficult task easy.

Machining the scroll recess was I thought going to be the hardest part. In the end I used a 40 degree included angle Vee tool, at 90 degrees tot he face. Similar to the standard Emco finishing tool. Plunging in 1.5 mm and moving in and out to just shy of the required finished diameters this tool removed the metal like a knife through butter. There was no hint of chatter either when I eventually had to form the 9 mm by 6 mm wide recess with a square ended trepanning tool about 2.5 mm wide. Once this was done It was possible to finish the rest of the recess with my insert boring bars.

To finish the 36 mm diameter the boring bar was used upside down and the lathe run in reverse. This whole operation was over in about 2 hours.

When it comes to reassembly the new front piece can be assembled in three positions. At each trail assembly the accuracy improved until at the last position, (it would have to be the last), I managed to achieve the best run-out results.

The worst TIR that I have is 0.04 mm, given the abuse that this chuck has received I consider that good, but I can improve upon it. There is a very slight Bell Mouth of Jaws 2 & 3 which I was expecting. As this is of the order of 0.01 to 0.005 mm respectively it does not affect the chuck. As proved yesterday while parting off the aluminium backing piece for the new Logo. Again this will be attended to once the internal grinding wheels have arrived.

This project has shown me one thing, and that is the Compact 5 can punch well above its diminutive size. Despite having what some consider to be an inferior bearing arrangement this machine performed faultlessly and above all accurately. I would certainly like to shake the designers hand.

I am tempted to grind the face and outside diameter of the chuck body with the toolpost grinder, but to do this will require an additional mounting block to bring the grinder closer to the operator than it does on the Emco topslide.

Regards

Gray,

 

[Graham MeekParticipant @grahammeek88282]

I have had a few requests for the details of the Soba 3 Jaw chuck Adaptor, so I thought it would be good to show the details here.

The spigot on the end of the Chuck Key will need shortening as the M5 attachment capscrews pass through the original Chuck key spigot location holes. It pays to reduce the length gradually, if this is over done the key will grate with the gear on the scroll.

Regards

Gray,

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