Well the FB2 and the Maximat Super 11 have now gone and the Screwcutting Clutch for the Compact 5 is now up and running. Along with a dedicated Retracting Topslide.

Work has now transferred to getting the Proxxon Mill to where I would like it to be.

The work on the Powered table feed is now complete as shown above. This has been used by jury rigging the wiring to produce the Delrin Connector block, come Micro-switch housing, as well as the End Cap for the motor. The finish produced by this small machine has impressed me.

Please ignore my makeshift base for the milling machine. Work is in hand to make a base similar to my Unimat 3 base in the background.

The Switch nearest the milling table engages the drive via a Dog Clutch. The Dog Clutch slides directly on the "D" shaped drive spindle on the reduction motor. As well as the drive shaft for the table feedscrew. Making the D-shaped hole was simplified thanks to an idea given to me by John Slater. More on that at a later date hopefully.

The second switch controls the direction of travel via a pair of micro-switches. Power currently comes form my Proxxon Micro-Mot power supply. This has a variable output and gives quite a good range of feeds with the 60 RPM motor. I may at a later date make a dedicated 12v power supply and control this via a PWM.

The Feed Unit was designed originally for John's X1 milling machine, another of our joint ventures. Thus it would be possible to adapt this design to fit most of the smaller milling machines. It would only require a different Endplate

One possibility I am mulling over at the moment is a variable power feed for the Compact 5 Leadscrew using largely the same design.

Regards

Gray,

Hi Jamie,

The Compact 5 Mill was my first choice when replacing the FB2, but as you know these are like Hen's Teeth.

You are right in your assumption about the cross pin driving the feed screw. Holding the feedscrew in a collet and reaming a hole was the easiest option. Using a Woodruff cutter it is a simple matter to put in the slot, which does not need to be a good fit on the drive pin. I used a 3mm pin with an 1/8" or 3.2mm wide slot. This avoids any slot symmetry problems.

Hi Steve,

I am hoping in due course to write an article on the feed unit. Maybe I can get John to do a 3D of the design in the meanwhile.

Hi Bernard,

As with my answer to Steve, it is my intention to write up this modification later on and if Neil is agreeable I submit the article.

Generally,

As regards Stepper motors this is a bit too complicated for me, and I do recall on some machines fitted with stepper motors I have used, that Cogging is an issue especially when trying to make small adjustments.

My method is dead simple, this gives me no such problems and the only cost is the 12v 60 RPM gearbox motor, the power supply I already had.

Regards

Gray,

Edited By Graham Meek on 25/07/2022 19:33:10

John Slater has once again worked his magic on my drawings and made things hopefully a lot clearer as regards what is going on, on the inside.

Two simple eccentric cams work the two micro switches to give left and right feed directions.

The Dog clutch is a little more complicated but both sets of Selector Knobs have a spring loaded ball to ensure the knobs stay engaged, or disengaged, during any vibration that might arise due to intermittent cutting action.

Regards

Gray,

Edited By Graham Meek on 04/08/2022 17:28:52

A lot of the modifications are coming to an end, however there are one or two items that need rectifying. When I set this mill up for the first time. I decided to do some alignment checks. Tramming the head was a must and here I had a shock.

There was nearly 0.2 mm run across the table when rotating the clock held in the spindle over the width of the table. This was not something I was expecting from Germany. Some of the run was attributed to the Column not being vertical.

The column has a turned down portion on the end to fit in a hole in the base of the machine. The problem was there was 0.03 mm taper on this turned down portion. Smaller at the bottom of the column. Because two 8 mm grubscrews to the rear of the column are used to clamp the column in place. The bottom M8 screw was pushing the column over due to the taper on the spigot. This made it lean away from the operator.

To overcome this I inserted a tapered steel plug inside the tubular column. This was drawn into place with an M8 piece of studding and a roller thrust race under the nut. This rectified the taper and also made the clamping area solid. The column now sat dead vertical as I would expect. Why the column is turned down 1 mm smaller escapes me. It is an un-necessary operation, why not make the hole 1 mm bigger.

However the run still existed but luckily it was much less, but still more than I was willing to live with. Enter the milling head from a spare second-hand milling attachment. Clocking this head showed very little error. Thus there was a duff part somewhere.

Thus it now has become the time to sort this problem out.

This is the setup used to track down the error, above I am checking the first side before rotating the Quill housing on the parallels.

These next two photographs show the the readings at these points.

Whilst 0.04 mm might not seem a lot this is only half of the error across the width of the table. (The Quill Housing is half the width of the milling table).

Now I knew where the error was time to set about fixing it.

More on that later,

Regards

Gray,

Hi Michael,

Thanks for the kind words, in an ideal world the part should have gone back.

Unfortunately post Brexit things from the continent now take months instead of days. I had waited 3 months for the milling table base to go with the vertical attachment I already had. In the end I purchased a complete machine.

Thus getting a part replaced under warranty would just take too long in my book. There is also the chance that the replacement will be no better.

The actual amount of material removed was miniscule to correct the part, but I am not impressed with my set-up. It was hoped to machine the offending face of the component using my homemade boring & facing head. While the head had sufficient travel to do the job in hand, the head would not extend far enough.

As the Proxxon is now my only working source of milling machine, (The Unimat 3 is still waiting for attachments), it was either strip the set-up down and make an extension holder for the boring bar, something that is now underway. Or adapt something to extend the range of the existing boring head.

I have had for some time a small manual boring head. This has a detachable 12 mm shank, so a new 8mm one was made and the additional boring head offered up. At the bottom speed of 280 RPM I was expecting the machine to throw a wobbly, but it did not show any signs of complaint.

Whilst the set-up had more overhang than I would like it performed the job in hand to my satisfaction and produced an excellent finish. The swarf can be seen on the boring bar.

Re-assembling the milling machine it would be nice to say it was perfect upon re-checking. I had decided I would accept a total run-out of 0.05 mm. Luckily it was less than this at max error of 0.01 mm, thus a mornings work including the photo session was well worth the effort.

After all I had a result the same day. Despite the poor engineering of the machine it is still a good design and works well given its diminutive size. The Proxxon School Report would read "could have done better"

Regards

Gray,

All the right letters but not in the right order!

Edited By Graham Meek on 15/10/2022 13:04:29