Touch DRO on a Axminster (Sieg) SC4 lathe

[GreatOldOne]

Here's my Axminster lathe, which is a re-badged Sieg SC4:



The cross slide gauge is mounted such that the graduated side is facing inward, and a shield put over the top of it. This keeps the majority of the swarf / chips out.



The longer bed scale is mounted to the back of the bed under the saddle, with a bracket that clears it's shield / guard.



The tach pick up is mounted in the headstock. Two rare earth magnets have been glued to the spindle:



The interface is mounted on the wall behind the lathe.


And here's some video of it all working (you'll note it's a different tablet in the video - this was my original HP slate which died. I'm now using Amazon fires on both my machines).

[Mick Eagle Walker]

Thanks for sharing I will be doing my G4000 Grizzly lathe soon. May need some support. Great job on mounting the scales,love the Stand for Tablet.

[GreatOldOne]

Thanks for sharing I will be doing my G4000 Grizzly lathe soon. May need some support. Great job on mounting the scales,love the Stand for Tablet.

Sure - happy to help. Shout when you're ready. 

[9942723]

GreatOldOne

Newbie... Brad from Seattle-

Thanks for the post with pictures. I do not understand why you have two (2) magnets on the spindle for the Tach. For RPM's I have only seen one (1) being used by others. Can you help me oh GreatOldOne. :-)

Brad in Seattle

[GreatOldOne]

more pulses per revolution - that's all. From my understanding, the more pulses you have, the quicker the response to a change of speed

[Eskimo2k]

More magnets allows for better resolution of the speed at lower RPMs. The trade off is that the more magnets you have, the lower the top end speed that can be determined is, but the better the resolution.
For example, if you have 1 magnet, you may be able to have a top end of 60000 RPM, but you can only have a read out in 1000 RPM increments (that's the resolution). If you have 2 magnets, you will only have a top end of 30000 RPM, but a resolution of 500 RPM. (The resolution numbers are completely made up, I didn't do the math, I only used those numbers as an example)
For lower speed operations, such as turning on a lathe, more magnets is generally a good thing.

I have 6 magnets on my mill, which gives me a top end of 10000 RPM with the code that I'm running (1 sample every .001 sec).
Since my mill isn't capable of that speed, the resolution is excellent.

[GreatOldOne]

A small update: 

The orientation of the cross slide scale has been changed, and is now attached to the swarf guard. This gives better access to the new carriage lock bolt (no matter where the cross slide is positioned). 

The new locking bolt has a 7mm hex head on it rather than being a socket head cap screw. With the new scale location, a 7mm open ended spanner easily swings under it.