Mount Table on to Saddle

[electrosteam]

Some progress on my Kondia CNC mill, it is now ready to install the table to the saddle.
The table is currently inverted on saw horses, which are too low for the saddle.
I have a scissor lift trolley rated for the weight, and with 50 mm packing, can get the height for the saddle.

My plan is to line the 50 mm packer with something slippery, and simply slide it on.
Any suggestions on improving my plan ?

John

[Michael G]

I was wondering whether some lengths of pipe/ bar stock may be better than 'slippery stuff'. If the saddle is even slightly weighty, getting it to move could be a challenge.

Michael

[electrosteam]

Job done, done as first described.
Used a plastic coated kitchen cupboard door as the slip surface coated with ISO68 to reduce the friction.
No drama at all.

The ballscrew is not yet connected to the table as the stepper motor mounting plate has some very bad countersinks for the capscrews.

The first job was to improve the countersinks.
The photo shows the plate on the table using a centering probe to move the job onto centre of the existing hole in the mounting plate.

Used an alignment jig with Dia 8.2 mm into the capscrew hole and Dia 10.2 mm for the centering probe.
The probe has a Dia 10 mm tip.
The jig was made with OD 24.00 mm that could be useful for future applications..

Centre was achieved by manually adjusting the Y-axis ballscrew and hammer tapping the job in the X-axis.
Not hard at all, and good enough for the application.

One issue with the probe is the hang-out, something that will have to dealt with.

First cuts were with a single flute 90 degree cutter, but just no progress.
Changed to a 3-flute 90 degree cutter with WD40 giving a perfect result.

Now to fit the stepper,
John

[electrosteam]

The table bearing support end cap needs roll-pins to prevent vibration loosening the capscrew fixings.
I am sure I mentioned these roll-pins previously, but I have lost the thread reference.

The issue is that as I have changed the end of the table onto which the end cap is fitted, there is no guarantee that the existing roll-pin table holes would align with the end cap holes.
Also after a pull-down and rebuild the ballscrew position could very well be slightly different.

I elected to add T-slot inserts at the table end that could be used for new roll-pins, and to drill the end-cap for these roll-pins prior to mounting.
The photos show the inserts compared with a standard T-nut, and the three inserts in place with JB Weld adhesive.



John

[electrosteam]

Just did a test piece aimed at checking the backlash.

LibreCAD to generate a dxf file containing a 42 x 49 rectangle.
CamBam to make two GCode files with:
- 13 mm diameter tool,
- 12 mm diameter tool.

Cast Iron 10 mm thick.
Spindle at 750 RPM, feed at 200 mm/min.
Ran 13 mm code with a 12 mm diameter ripper cutter.
Cut 0.4 mm depth and width variable 0.5 mm to 10 mm.
This left the piece 1 mm oversize in each direction.

Then ran the 12 mm code with a new 12 mm diameter end mill.
Cut 0.4 mm depth and 0.5 mm width.

The photo shows the ripper cutter part way through.
385175

Finished test piece is Ok, without being spectacular.
I intend posting a photo in a separate thread as it has interesting striations that would be of interest.

Size measured as 41.98 x 48.94 mm.
So, backlash estimated as:
- X-axis 0.06 mm,
- Y-axis 0.02 mm.

A bit disappointing on the X-axis, but I can live with it.
John