Clock Stand with a difference

I have managed to finish the Slider today, so took the opportunity to do a second check for Perpendicularity.

Since posting on here last John Slater drew my attention to "Monday Night Meatloaf 116 P2" on YouTube. Tom Lipton is making a similar dedicated device and has a novel way of checking the perpendicularity.

I had watched this sometime ago but forgot all about it in the interim, so I must thank John for refreshing my memory and saving me some work.

Rather than make something as Tom does in his video, I have used a piece of M8 Studding (Allthreads) and one of my Milling clamps to give the same results. Note the Ball bearing to give point contact at the top of the Column.

In this initial set-up I had an light reading, (error), of 0.005 mm at what will be the front of the Clock Stand. This I expected as my first tests before showed a slight lean on the Column of this magnitude towards the centre of the Clock Stand. The clock is sweeping a 200 mm diameter circle and the location points in the FB2 shots were about this distance apart.

Rotating the Clock Stand through 180 degrees and repeating the check showed a similar error but this time it was only 0.003 mm. I know from the report that came with my surface plate that it has a slight hump. Thus when it comes to chasing these sort of errors there comes a time when it has to be accepted that this is good enough for the workshop concerned and any further work is meaning less.

One thing this check does show is that the first set-up using the FB2 Mill is a sound one.

Regards

Gray,

A good job, Graham!

To get within a few microns in a home workshop is excellent accuracy, and as stand for a clock, it will not be subjected to the forces that might be involved if it were used a height gauge to scribe lines.

As usual, WELL DONE!

Howard

Nice one Gray. Apart from making a very useful instrument it's a very clear demonstration of prescision setting up techniques.

regards Martin

Thanks Howard & Martin for the kind words,

I used the Clock Stand Column the other day to check out the Geometry of the FB2 Main Column. Using a clock in the collet holder and traversing over the Clock Stand Column using the Z-Axis.

I have always known there was an error but without something truly perpendicular it has not been possible to check this before. I had thought the error was quite a bit larger than I eventually measured, but at 0,02 mm, (in the Y-Axis Plane) over the entire Z-Axis travel I am happy with that. In the X-Axis Plane it is possible to adjust for a zero reading.

It will be easier once I have installed the drive mechanism to traverse the Slider on the Clock Stand. Then any clock can be held in the Slider and traversed vertically over the item being checked. I have ear-marked the Emco Angle plates as the first items to get this treatment and to finally be rectified.

Regards

Gray,

I have finally managed to finish the Multipurpose Clock stand. The clock fitted in the above photograph reads 0.002 mm and was a given to me by a friend. When using this in my Starrett Scribing Block I could seldom get the same reading twice. The weight, stability and improved locking mechanism on the above clock stand has made it all worth the effort. The clock now gives the same reading time after time.

This next photograph shows the Slider to Read-out connection. I am indebted to John Slater for this suggestion. It is piece of Pinion Wire and allows the two units to move laterally independent of each other. I am also indebted to Ketan for supplying the DRO after an enquiry for a drawing. As I have stated previously this was only added as an after thought on my part. The mounts for which are dead easy to make.

This shot also shows Locking Knob which works on a separate shaft and thus does not influence the clocks setting. The Locking pad is spring loaded which always ensures a constant pressure on the rear face of the Column by the Slider.

This shot shows the Handwheel in the inboard position which gives a direct, or rapid traverse.

Pulling the Handwheel out engages a reduction drive of 4:1 for slow traverse and clock or DRO setting. The traverse is taken care of by an MXL toothed belt sunk into the Column. There is a tensioning adjustment incorporated in the top belt anchorage.The belt being sunk into the column ensures the teeth are always kept clean. The drive I was expecting to be a little Notchy but in the end my worries were unfounded.

This check was to verify the perpendicularity of my work. Running the DTI up the side of my homemade Cylinder Square and then turning the Cylinder through 180 degrees showed no error. Which was very satisfying.

The DTI can be mounted in the Vertical and used to check heights of components. Both as a comparator or in conjunction with the DRO.

This shows the scriber fitted for use as a digital Height Gauge. It takes literally seconds to change from one to the other. The scriber proper is a separate piece bolted to the end of the holder.

Finally checking the perpendicularity of the Proxxon Milling machine Column. While the clock position is not ideal and no reading at such an angle could be trusted. Using the clock in conjunction with the feedscrew does give a quantifiable reading. Which in this case was a lean backwards of 0.03 mm over 150 mm plus of vertical travel.

Given the weight of the milling head this will probably rectify this error.

I hope you have enjoyed this little device.

Regards

Gray,

What a superb instrument and beautifully executed. I do hope I will get a suitable fitted case.

regards Martin

Thanks Martin, I had not considered making a case, but it would be nice to give it a good home.

Regards

Gray,