I got an RC-210E

Let me preface this by saying I’m not a lathe guy, I’m a mill guy.

I’ve been using the same micromark branded sieg c3 for more than half my life to pretty good effect because I’m usually only making smaller shafts and specialized fasteners under a half inch, but lately my needs have grown to include motorsports axles and super charger rotors which won’t fit on a 7x14 lathe.

I originally wanted to get a precision matthews pm-1236t, but since the time I’ve been considering it to now the price has risen 3000usd from it’s original 4000usd price to 7000usd and I can’t justify it anymore because of how infrequently I actually use a lathe.

I ended up getting one of the super-extended sieg c4’s, an 8.5x31.5 with an electronic lead screw. I’m mostly making this post because I don’t see anyone else on the internet reviewing/testing it.

I’ll post more thoughts/tests in the future but so far:

Pros:

  • Came very well crated with no damage
  • Only weighs ~150lbs which means I can move it by myself
  • Initial inspection of all ways indicate good grind and minimal dings
  • Has oil ports
  • Has electronic lead screw (no more changing out gears!)

Cons:

  • The MT5 spindle bore is not deep enough to hold the MT5 test bar I bought
  • Very very slight surface rust in spindle taper
  • Only weighs 150lbs, the “real” lathe guys will say a lathe this size needs to be atleast 800lbs
  • All the leadscrews are metric
  • Spindle motor shaft keyway is undersized for the key (key falls out)
  • No power leadscrew dust cover

In the future I’m definitely going to get a quick change toolpost, I’m leaning toward the Indian QCTPs instead of the Chinese QCTPs. I’ll also look to remove the metric leadscrews and dials and replace them with Inch to improve usability… the rack on this thing is graduated into 90 0.25mm ticks per revolution… who thinks that way?

3 Likes

I finally got around to getting the test bar fitted, the “surface rust” in the spindle taper was deeper and more stubborn than I thought it would be which slowed me down.

I’m satisfied I have the test bar fully seated in the taper.
3.1" from the Spindle flange I’m getting 2 tenths of runout which is outstanding, moving out 14.7" from the spindle flange there is 4.5 tenths of runout which is very good, the bearings have proper preload for there current un-ran-in state.

Next I tested the bed straightness and this is where I’ve got some problems. I tested at one inch increments to rule out head nod/misalignment if the measurements don’t grow linearly. At 14.1" from the spindle flange I’m getting a 13 ten thousands of an inch droop and 55 tenths movement toward the operator.
I’m hoping this is bed twist and I can address it by bolting the lathe down to a plate and shimming appropriately. I could probably glean more information about the twist if I retry the test with the cross slide in a different position.

I also check the bed hardness with my new tsubosans; I’m getting right between 45 and 50 HRC.

2 Likes

Hi There,

I too am intigrued by this lathe. The servo/stepper driven leadscrew would seem to solve the conundrum of change gears or (very) limited gearbox options (still with change gears). The rest of the machine seems to be a stretched and raised version of the ubiquitous 7x14 mini lathe.

Have you had a chance to test the electronic leadscrew yet?..And???

Thanks - Malcolm in Canada

Hey!

Exactly, changing out the little gears on the sieg c3 lathes was a pain… Although tbh with this lathe, going through menus to select a pitch is semi-annoying to me as well, but I suppose it can’t be helped with all the different modes they programmed in. One of the more useful modes is a thread stop mode where it’ll automatically stop after it threads in a certain distance that you can specify (no more quick drawing on the crossfeed lever).

The stepper motor that drives the electronic leadscrew on the lathe is fairly powerful, it can do some relatively (for the size of the lathe) deep cuts without stalling out, its a nema 23 with a fairly substantial gear reduction.

So far to me the weakest part of lathe is the way they did the bearings (or lack thereof) on the crossfeed and compound slides; its effectively just a flange in the hard feed screw pushing up against mystery metal (some kind of zinc alloy I think?) retainers.
I’ve gone down the rabbit hole of trying to improve upon the design by adding in dedicated bearing bronze thrust washers and preloaded thrust ball bearings to make the feedscrews more consistent.