Sieg SX2P – DRO, power feeds, CNC? What first?

[JasonBModerator @jasonb]

If you go the the Workshop section of the site and have a look at “Getting the most from your brushless mill” I cover speeds, feeds, depth of cut, etc there. These small hobby machines benifit from a slightly different approach the the more traditional methods described in some of the older ME publications.

Higher spindle speeds, faster feeds and lighter depths of cut are the way to go.

[Russell EberhardtParticipant @russelleberhardt48058]

If you’re thinking of doing a CNC conversion later don’t waste money on digital readouts first as that will become redundant.  I have direct readout scales on the X and Y axis of my larger manual mill and wouldn’t be without them.

Back in 2012 I bought an SX2P with the express intention of converting it to CNC.  For such a small mill I considered the existing x,y leadscrews to be adequate but with improved end bearings and acetal anti backlash nuts.  The Z axis was a bit more involved fitting, a ball screw.  My build log can be seen here:

https://www.mycncuk.com/threads/4524-Sieg-SX2-Plus-build

I have found it to be useful for making small intricate parts for clocks.  I think it might be time soon to upgrade the electronics as the computer I’m using, one of the few with a parallel printer port, is getting to be rather old.

Russell

[John HaineParticipant @johnhaine32865]

Nice conversion Russell. Another option would be to mould Delrin nuts around the existing screws perhaps? I’ve seen that described on here a while ago.

[nevilletParticipant @nevillet]

Regarding the collet on my Sieg SX2P mill, it came supplied with a ER25/R8 and 4,6,8,10, 12 & 16mm collets.

Taking a look at Russell’s tread on the MYCNCUK forum regarding the CNC conversion it’s not an insignificant project!

I was hoping that the motors would be smaller and take up less space.

[John HaineParticipant @johnhaine32865]

The motors are NEMA23 which is fairly standard for a mill, though at the the X axis looks like a higher torque one so is has a longer “stack”.  Next smallest motors are NEMA17 which I don’t think would have enough grunt for ordinary screws though they might work with ball screws.

[JasonBModerator @jasonb]

The Motors can look big on many conversions as they are usually just stuck out the front. My purpose designed CNC has the Y axis motor at the back under the column so looks a lot less bulky and you can get right up close to the table.

[nevilletParticipant @nevillet]

Looking at the NEMA 23 motors, what sort of Nm torque spec would be suitable for the X feed?

[JasonBModerator @jasonb]

My larger KX-3 has 4Nm on the X & Y, the smaller SIEG KX-1 has 1.35Nm so something around the 2.2Nm would probably do going up to 3Nm for Z

[nevillet]

On nevillet Said:

…Straight out of the box, I started milling some oak, progressing to brass and then mild steel.

On the steel I think I was using a too low milling speed (not wishing to Muller the cutter) but having a juddering initial cut. As my confidence grew so did the speed.

…

Hint!  Avoid cutting wood in a metal workshop!   Various problems, like cutters and speeds being inappropriate for wood, but the biggie is sawdust does horrible things to precision machine tools.    It penetrates into slides and bearings where it absorbs lubricants and traps swarf, creating an abrasive!   Plus some woods are acid* and they are all wet – corrosion!

Needs must when the devil drives, but lay sheets to stop sawdust reaching the machine’s innards and make sure the slides are clean.

The opposite applies too: avoid cutting metal with woodworking machines!

Dave

* There are about 500 different Oaks and some are very acid.   Some oaks are ideal for making tool-cabinets, others cause severe corrosion.

[John HaineParticipant @johnhaine32865]

You could measure the required torque once you have the new screws/nuts installed.  An adjustable torque wrench could do it, or a suitable lever and spring balance.

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