Member postings for Raglan Littlejohn

Dan,

Thanks for your kind comments, I'm pleased you got a positive result. I hope you have success with the other problems on your machine.

John.

Dan,

I think what you suggest should result in a much more accurate measurement. It would be better to attach a plunger type indicator to the bottom of the quill, but thats probably not very practical.

John.

Dan,

I did not mean the dti could turn the chuck. The spindle must be driven by a splined coupling. There must be slight play if you rotate the chuck clockwise then anti clockwise by hand. that play may be enough to give a false reading. It's also possible theres a spline driving the spindle which is slightly helical. This would not matter in normal use, but would cause the error your seeing.

John.

Dan,

How can you be sure the chucks not turning slightly as the quill moves up and down.

John.

John,

Thanks for the update on the firmware. I've just realised www.mesaus.com is run by a prominent member of the Linuxcnc forum, so support for the firmware will be good. The 5i25/7i76 seems a good combination for me, I can start with that for step/dir set ups, then replace the 7i76 with a 7i77 if I want to change to a servo set up.

John.

John,

I am also looking into purchasing some Mesa boards, so thanks for the link www.mesaus.com. Their site has a simple explanation of what the Mesa cards do ie they list stepper solutions in one box, then servo solutions in another box. They also show where you plug the card in eg PCI Bus/5i25/7i76. I've found it hard to find simple details like this on these cards. I wonder if the lack of basic info is due to the large number of possible combinations of control available?. Please could you advise if your 5i25, 7i76 came with the correct firmware, firmware seems to be a possible problem area.

John.

I've drawn a simplified version of this using Design Spark, I left out the equatorial joint as suggested by Bazyle.

I used a helix of 600mm pitch. There are 14 x 3mm wires in each direction. Bit of a job in Design Spark as it has no 3d mirror function.

I think annealed 3mm brass would do, maybe formed over an old bowling ball or similar. The joints could be soft soldered.

John.

www.lasermaster.co.uk will do these two for £12.40 +vat including postage. No need for a drawing. Just put the size you need on their order form, and you get an instant quote. I've not used them yet, but will when I next need something made. (Probably cheaper than I could buy the steel and make it myself).

John.

Andrew,

The angle on mine is 16.5 degrees. it is the large Steam Fittings lubricator, and this is the minimum it will work at reliably. there is no problem with the clutch running in oil so far, maybe the type of oil affects this. I think any misalignment of the clutches is the main cause of problems.

Regards, John.

Andrew,

I had problems with a commercial lubricator I bought a couple of years ago. It used a hardened steel shaft with roller clutches, and was unreliable. I fitted new clutches but it still failed. The shaft was only supported on one end were it passed into the tank. It was tilting when the pump plunger was forced down by the cam. I made a new shaft from silver steel which I hardened right out. I also drilled a hole in the other side of the tank, in line with the original bearing. The new shaft went right through both holes and was supported at both ends. The tank material was thick enough to use as a bearing so it was an easy job. It's worked fine ever since, and the feed is easy to vary if needed. I emailed the manufacturer to explain the problem but had no reply.

Hope this helps

Regards, John.