After deciding to downsize my workshop in January, the need to get the Compact 5 (C5) up to a standard I was comfortable with became a priority. The use of my larger machines would be of benefit while they were still here.

Having had the luxury of the Screwcutting Clutch on the Maximat Super 11 it was something I was not happy to do without. The C5 had always been tempting me to do this mod, so during my recuperation in February I set about designing the attachment.

The above view shows the Mk1, and it also shows you really need to be in the workshop more. The reason being I had forgotten to allow for the dis-engagement of the Leadscrew. This being a necessary requirement on the C5, other wise in Manual mode the operator has to turn the banjo gears as well.

This need to retain the C5 disengagement Knob meant the Operating lever would need to move from the chosen site where the knob was to in front of the headstock. Thankfully during the need to do a complete redesign of the main body it was possible to have both controls in the one place.

The keen eyed amongst you will notice the main body is now in two halves, or parts. Again had I have been a more frequent visitor to my workshop at the time, I would have noticed the Bracket welded to the inside of the Headstock cover, which takes the cover locking screw.

Had it been possible to retract the leadscrew with drive key attached through the bearing in the lathe bed, then the original design would still have worked. Unfortunately the key stands proud of the shaft and this cannot happen. Thus there was nothing to do but start again with two halves, and yes this was after I had machined the main body in one. Of course I could have cut the bracket off, but that is not how Graham operates.

The redesign also threw up another problem, in that the Dog Clutch, because of the split line needed to sit higher in the upper part of the main body. Unfortunately this brought the dog clutch selector into conflict with the drive belts when changing to the lowest Mandrel speed. This was eventually overcome by machining a flat on the selector similar to the flank on a camshaft. An eccentric balance weight is yet to be made and fitted to the outer end of the selector shaft.

A new bearing assembly was also made for the Leadscrew handwheel which has some Radial ball bearings in. The housing was extended towards the Headstock to provide the anchor point for the outer Trip Rod support. The ball bearings will eliminate wear to the leadscrew end face and give better repeatability when screwcutting.

While I have used this lathe for screwcutting in the past, it was a rather hair raising experience. This attachment now completely eliminates the heart stopping moment as the tool approaches the chuck jaws.

I will in due course go on to describe other attachments for the C5, two of which get the benefit of the screwcutting clutch. I hope you have enjoyed my rather long winded post.

Regards

Gray,

Edited By Graham Meek on 15/05/2022 11:20:55

Edited By JasonB on 30/06/2022 20:35:31

One thing I did forget to mention is that the gears were made using the Emco Compact 5 Dividing attachment and are all 1 MOD.

Regards

Gray,

Dear Jouke,

Stops on the trip rod running along the front of the machine can be set to any desired thread length, with-in the limitations of the machine. The trip rod moves to the left or right depending on the operating lever position. Which dictates whether the the thread is a RH or LH. Moving the operating lever to the right means the trip rod moves to the left and visa versa.

The operating lever works the banana shaped plate, at one end of this is the trip rod and at the other is the dog clutch selector. Thus any movement of the trip rod directly affects the dog clutch selector.

As the carriage moves along the bed during screwcutting it makes contact with the stop, 2.5 mm later the dog clutch is disengaged. Moving the operating lever in the opposite direction, after withdrawing the tool, returns the carriage to the start position.

As there is only one tooth on the dog clutch it can only pick up the drive at one pitch intervals.

Regarding the hand wheel position, this end was chosen so as to utilise the existing leadscrew nut fixing position and to retain the original operating force position on the carriage.

In my experience there is always a dead space at the headstock end of the bed due to the chucks, faceplate and catch plate attached to the mandrel. I therefore did not consider there would be much loss of travel. However in this instance I may be wrong.

I hope these notes help,

Regards

Gray,

PS

I have just completed a new topslide feedscrew using the above attachment, I hope to post a photograph soon. Which is for the next phase of the mods, a Retracting Topslide.

Dear Jouke,

The leadscrew engagement on the Handwheel conversion is carried out by the lever on the left-hand side of the carriage. This lifts a cylindrical half nut via an eccentric into engagement with the leadscrew. The cylindrical half nut is keyed to stop it rotating so alignment with the leadscrew is always assured. (One half nut has been used on numerous occasions in the past by various lathe manufacturers).

While your C5 powered cross feed sounds an elegant design. I think if I were trying to do this I would start with a C5 CNC cross slide and carriage assembly. These regularly come up on the Internet for sale. I think this would be an easier starting point. A plus point is these parts are, I believe, made from Cast Iron.

With regards to my design modifications. I pride myself in that I do not modify the existing machines in any way. I always make use of existing tapped holes for attachment points. No existing Emco part was modified in this recent design and my C5 could be put back to standard in a matter of minutes.

Regards

Gray,

Despite the workshop being in mess due to the larger machines going. I have had a chance to make the new Topslide Feed screw and the Main Body for the Retracting Topslide.

This was machined on the C5 from a long old 10 mm bolt. I find this material machines well and screw cutting is a pleasure. As was using the Screw cutting clutch on the C5. Of course it would have been quicker with the retracting topslide.

The Main Body was machined on the new Proxxon Mill and after locating all the holes by co-ordinates the bores were finished on the C5 using the 4 Jaw chuck.

Regards

Gray,

I thought those Compact 5 owners with cross slide feedscrew backlash problems might like to see what was in my post from Emco Holz & Hobby this morning.

This is a brand new part and machined from the solid. It utilises the newer inserted feedscrew nut with backlash elimination. I think most of the feedscrew parts are available separately.

The underside view shows the bearing surfaces to be continuous not as in the original die cast version, which had pockets moulded into the bearing surface. Because there is now probably more bearing surface the width of the Carriage has been reduced by 15 mm. From what I can tell most of this is taken off the front edge of the carriage.

Regards

Gray,

Hello Jouke,

My wording of the actual reduction in width, may have mis-led you somewhat. The dimension from left to right of the carriage, the bit that sits parallel to the lathe centreline has been changed from 115 to 90 mm.

I was aware of the changes made during the Emco upgrade, and I think my ball bearing version for the cross-slide Handwheel Bracket will restore the correct travel on the earlier lathes. As well as giving an improvement to the cross-slide handwheel bearing.

Regards

Gray,

Hi Jamie,

Some how I do not see your first sentence coming to fruition, but it is a nice thought on your part.

I am just in the process of making a Jpg of the drawing for this Handwheel bearing mod, maybe I can post it later today.

As regards the spares there is a considerable amount still available, even a new lathe Bed. There are two different versions as regards the Carriage, one Metric and the other Imperial. The cost at the moment is 108 Euro's for the metric one. Which I thought was good value for a new part. Postage is about 28-29 Euro, and as regards the import duty I think this is on a sliding scale. How it is worked out I have not got a clue. My order came to more than the above 108 Euro, and of course they have to add in a "Handling Charge" which was £12 on its own in my case. You actually pay Parcel Force what is due.

I hope this helps?

Regards

Gray.

Hi Howard,

I am humbled by your comments.

My Father was responsible for the standard of work I produce. He gave me the desire to always look to do a better job and the skills to do it with. Plus I had some of the best training available during my apprenticeship.

Having been used to a better machine in the Maximat Super 11, the Compact 5 is now reaching a standard at which I am more than happy with. This machine continues to surprise me as regards it's accuracy, what work it can do and the finish it produces. Obviously you do not watch the clock as things take a bit longer than they did, but I am beginning to enjoy my machine time more.

Regards

Gray,