# Sieg SC8 and its spindle mount



## joshua43214 (Jan 8, 2015)

hopefully this is in the right place

I am considering a Sieg SC8 from DroPros
http://www.dropros.com/DRO_PROS_Sieg_SC8_Lathe.htm

This seems to be about the only alternative to the PM1030 (except the over priced BT1030A from the scary Bolton people).
It has a potentially deal breaking issue though with the spindle mount.
You can see some images of the spindle mount here
http://www.mini-lathe.com/reviews/Lathes/Sieg_C8/C8.htm
It looks a bit dodgy to me, but it might be fine.

Does any one here have any experience with this lathe?
I called DroPros and was told that the spindle mount was proprietary to Sieg. But he also told me that it had a metric lead screw (it turns out it does not), and that a metric lead screw cuts perfect Imperial threads (which is nonsense).
All they carry are Sieg 4jaw scroll chucks (which are rumored to be crap), no independent chucks. They do not carry any faceplate adaptors. I was told that they leave the little stuff like that to LMS.

So I called LMS and they have no clue what the spindle mount is, but they hope to get something together by this summer, maybe.

I could only find two reviews of the lathe online. One is on the mini-lathe.com site, and the author mostly just gushed over how massive and solid the machine is (such is the life of a mini-lathe user lol).
The other was from a guy who never bothered with the chuck and just mounted up a collet system.

I despise proprietary designs for critical parts on principle. To make matters worse, DroPros seems to be the only North American distributor of this machine, and I do not trust them to keep selling them. As it stands now, the only way to get an adaptor plate is to buy a 4jaw chuck and take the adaptor off it.

Any light on the mystery would be greatly appreciated.
-Josh


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## darkzero (Jan 8, 2015)

The  SC8 spindle mount is similar to those found on most Asian import mini-lathes (which are Sieg variations also). The chuck will either have studs threaded into it or just threaded holes, and is bolted on to the backside of the spindle flange with either nuts or bolts.

I don't like these types of spindle cause they can be a pain to change chucks depending on the lathe design, especially if you have fat fingers. Most of these types of spindles don't have a nose taper for chuck registration, but not all. I don't favor spindles without a nose taper.

If you will be threading imperial threads most of the time & the SC8 is only available with a metric leadscrew, I would stay away from it. Metric lathes (metric leadscrew) can thread imperial threads that are close enough to work perfectly fine but you won't have the ability to use the thread dial "normally" (there is a method to partially use it but still).

(Moved to the Sieg section)


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## joshua43214 (Jan 8, 2015)

Ya, the nose does appear not have a taper, like I said looks a bit dodgy. I was hoping that maybe it had some way of centering the chuck that was not obvious.

The machine comes with either a metric or imperial lead screw. According to the manual, it has an 8tpi lead-screw, yet it threads down to 5tpi. It does not have a half-nut.

Shame about the spindle mount. No nose taper + no adaptor plates = deal breaker. This is essentially a collet lathe as it now stands.

-Josh


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## zimma (Jan 8, 2015)

I believe the spindle mount is a DIN 55022 mount. I have the SC6 and have never had any problems with it. Ive made several backplates to fit alternative chucks without a problem.

There is a built in taper to the end of the spindle, and the backplate of the chuck locates on this taper.

Graham


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## mattthemuppet2 (Jan 8, 2015)

The back plate seems pretty simple to me and the spindle mount has the benefits of a D type nose without the expense. It certainly has to be a step up from the threaded spindle found on smaller (or older) machines.

It has half nuts but the Dropros version doesn't have a threading dial which is odd, as it's on the standard C8. Perhaps an accessory that you can buy from Seig? It's a better looking lathe than the PM1030 in several ways, but less standard equipment. A better comparison would be the PM1127, but that's quite a step up in price with some extra features too.


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## atunguyd (Jan 8, 2015)

I have the SC8-PRO package that I got my local sieg agent to import (he didn't even know it existed).  The spindle mount is actually very nice and makes changing chucks a breeze with the cam system. I also ordered it with the 4 jaw but seig packed a self centering 4 jaw. So the agent gave me the SC6 chuck to try. It is 5mm smaller and just needed the adaptor plate to be bored out slightly to fit the SC8. Can't say I noticed a taper but if you want I can remove my chuck and check for one. 

Good news is that the adaptor plate for the SC6 can be readily modified for this Lathe. 

All in all I am very happy with it, a big step up from my 7x12 I had before. 

The pro package comes with DRO and flood coolant but the lathe is the same. 

Feel free to throw questions at me if you want more information. I was in the same boat as you - very little info out there on this Lathe. For me an old second hand machine was not a possibility as they are hard to find here in south Africa and the sieg agents are located in my town so at least I have some support. 

Sent from my GT-I9505 using Tapatalk


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## zimma (Jan 8, 2015)

atunguyd said:


> Can't say I noticed a taper but if you want I can remove my chuck and check for one.
> 
> Sent from my GT-I9505 using Tapatalk



Ive just been out and measured all of my backplates and also the spindle register for a taper. There isnt one, so apologies. It is not a DIN55022. From the looks of it, its identical to 55022 apart from the taper.

Graham


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## zimma (Jan 8, 2015)

joshua43214 said:


> Ya, the nose does appear not have a taper, like I said looks a bit dodgy. I was hoping that maybe it had some way of centering the chuck that was not obvious.
> 
> -Josh



There isn't a taper, but there is a register cut into the spindle that the chuck backplates locate on to center them.


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## joshua43214 (Jan 8, 2015)

zimma said:


> There isn't a taper, but there is a register cut into the spindle that the chuck backplates locate on to center them.


Thank you very much for going out and looking at things.
I figured this was how it worked. Looks like the chuck just slips onto the end of the spindle and is bolted on. Should work well enough, but there will be no moving the chuck from the lathe to a fixture, then back to the lathe again. Certainly better than a screw on chuck. Simple to manufacture, and a clever mounting system, I'd still pay a bit more for a proper mounting system that was not proprietary.



atunguyd said:


> I have the SC8-PRO package that I got my local sieg agent to import (he didn't even know it existed).  The spindle mount is actually very nice and makes changing chucks a breeze with the cam system. I also ordered it with the 4 jaw but seig packed a self centering 4 jaw. So the agent gave me the SC6 chuck to try. It is 5mm smaller and just needed the adaptor plate to be bored out slightly to fit the SC8. Can't say I noticed a taper but if you want I can remove my chuck and check for one.
> 
> Good news is that the adaptor plate for the SC6 can be readily modified for this Lathe.
> 
> ...



This is excellent news. I am pretty sure that LMS carries an adaptor for the SC6.

I am tempted by this lathe, but something inside me is warning me off.
I wish I could put my finger on the problem.


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## atunguyd (Jan 8, 2015)

joshua43214 said:


> Thank you very much for going out and looking at things.
> I figured this was how it worked. Looks like the chuck just slips onto the end of the spindle and is bolted on. Should work well enough, but there will be no moving the chuck from the lathe to a fixture, then back to the lathe again. Certainly better than a screw on chuck. Simple to manufacture, and a clever mounting system, I'd still pay a bit more for a proper mounting system that was not proprietary.
> 
> 
> ...



Ok this is the negatives of this Lathe:

1. The speed controller will not allow you to adjust the speed until the spindle is running. It would be nice to push the arrows to dial in a speed then hit start. 

2. I don't like the push button speed controls, I preferred the mini lathes dial add it was quicker to change speeds especially when threading with the half nuts locked. 


3. Minimum speed is 100 rpm it would be nice if I could get this lower. I guess a smaller pully on the motor would help here. 

4. Tail stock travel is somewhat short. 

As you can see there are no major shortcomings, just small things that can be overcome.  For the price it is a very nice lathe. 

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## joshua43214 (Jan 12, 2015)

OK. I think I finally figured out what was bothering me about this lathe.
It must have went into my sub-conscious when I was looking at the owners manual.

The left side spindle bearing is a ball bearing rather than a roller bearing like the right side bearing. To make things worse, the left side bearing registers against a circlip, instead of a machined in boss. The bearings themselves seem to be inside of grease shields with no provision for oiling. I imagine it is still possible to pump some grease past the seals though. Since the cost of machining a deep groove and using a machined circlip is higher than the cost of a second roller bearing, I seriously doubt that Sieg has engineered this set-up properly. I suspect it is just a stamped circlip (50% chance it is in backwards), and a cheap roller bearing designed for minimal linear load.

I can't help but think that Sieg is just making a larger mini-lathe, rather than a smaller tool-room lathe.

/sigh.
This means the choices for 10x30ish lathes are PM (you can get on a list and maybe get a lathe in 4 months), Bolton (cringe), Shop Fox (double cringe), Wholesale Tool (900lb lathe! may as well get a real lathe), or some clapped out Southbend that is 2x what it is worth.
I think I will go with the Bolton and pay a lot more than for the PM, but at least they answer the phone and can send me a lathe this week - one in the hand is better than two in the bush. The Bolton seems to be the exact same lathe as the PM with out the VS and other goodies.

Gah, just got a text from my ex-wife. She sent me a picture of the field from her seat at the OSU/Oregon game. :banghead:
Going to go vomit.

Thank you all again


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## mattthemuppet2 (Jan 12, 2015)

I'm not sure what the deal is? That bearing is almost entirely there just to prop up that end of the spindle and keep things straight, the one next to the chuck is what bears all the cutting load. As long as the right hand side bearing is preloaded properly, it's a non-issue what the left one is. You could make it out of a piece of sintered bronze and it would work just as well, only it'd be a pain to keep oiled.

As for greasing the bearings, if they come as cartridges and are sealed, then they don't need periodic greasing. The grease is supposed to last the life of the bearing.

I can think of many other reasons not to buy a lathe, but what type of left hand bearing it has isn't one of them. Hell, my old lathe doesn't even have bearings in the conventional sense, they're just 2 tapered holes in the headstock casting. Still works fine though, within and sometimes beyond the limits of the machine.


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## joshua43214 (Jan 13, 2015)

mattthemuppet said:


> I'm not sure what the deal is? That bearing is almost entirely there just to prop up that end of the spindle and keep things straight, the one next to the chuck is what bears all the cutting load. As long as the right hand side bearing is preloaded properly, it's a non-issue what the left one is. You could make it out of a piece of sintered bronze and it would work just as well, only it'd be a pain to keep oiled.
> 
> As for greasing the bearings, if they come as cartridges and are sealed, then they don't need periodic greasing. The grease is supposed to last the life of the bearing.
> 
> I can think of many other reasons not to buy a lathe, but what type of left hand bearing it has isn't one of them. Hell, my old lathe doesn't even have bearings in the conventional sense, they're just 2 tapered holes in the headstock casting. Still works fine though, within and sometimes beyond the limits of the machine.



Sadly, this is not really true. The rear bearing is under a lot more thrust than you give it credit for. Not only does it have to hold the preload for the front bearing, it gets pounded a bit each time the tool takes pressure off the work. This would never be an issue on a mini-lathe where the work is only a few ounces and the tool pressure is always very light. I do agree that it would be fine if proper preload on the front bearing could be maintained, but it can't. Not only will the rear ball bearing be over loaded, a stamped circlip is not meant for this type of application and will lose preload (not to mention the circlip can pop out of the groove if installed backward).

Just to be sure, I googled up the part numbers since they use standard item numbers for the bearings. Both bearings are just plain old fork lift bearings, and the circlip is just a plain old stamped part for a square shoulder. My very ancient Walker-Turner lathe uses a similar set up (it uses a machined circlip on the outer race of the bearing rather than in the soft cast iron), and I have ruined more than one work piece over the years when the bearing lost its pre-load. I am pretty sure this is caused by thermal cycling since a roller bearing can not be loaded sufficiently,

As for sintered bronze, it is only in very recent years that bearings have replaced bronze in precision machines, and they are still used in watchmakers and jewelers lathes. They run extremely smooth, are as close to being immune to vibration as a bearing can get, nearly immune to grit if properly designed, and last indefinitely if kept oiled. There is a good reason for why stuff that turns 100,000+ rpm use bronze (or air) bearings. I would not trust a Chinese factory to make or install this type of bearing though.

Now here is the funny part. I have almost talked myself into buying this lathe now. Class 5 bearings are reasonably cheap and it does not look difficult to replace the bearings and use a machined circlip.
For $2,000 this really is a lot of machine. It turns a bit too fast at 100rpm (still better than most other machines), but the feed rate is pretty decent for a small machine at .0016. I like the threading options. It is a bit light at 386lbs, but that can be fixed with some judicious use of concrete and that old slab of granite in my backyard.

Thanks for arguing with me. It got me thinking about a solution rather than focusing on the problem.
-Josh


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## atunguyd (Jan 13, 2015)

Josh with regard to minimum speed, remember this Lathe is derived from the C8 which changes speeds with pulleys which means there is ample room in the headstock to change the pulley on the motor with one with multiple steps. This way you can reduce the speed further. Downside is speed controller reports speed from the motor not spindle so it will not reflect true spindle speed but that is not a big issue. 

Sent from my GT-I9505 using Tapatalk


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## joshua43214 (Jan 16, 2015)

Well, I went ahead and ordered this lathe.

I still have some misgivings about it, but I have a lot more about the other lathes in this size.
My biggest concern is about support, LMS and DroPros are just pointing their fingers at each other saying "the other guys sell this stuff."

The lathe will ship this Monday. I will try to carefully document the unpacking and cleaning, take pictures, and measurements of various things, then do a full review.

I would love to know if I can squeeze a BXA size QCTP onto it for instance. I know the AXA fits, but it would be nice to get the extra mass and larger size tooling on the machine. My gut tells me that a BXA will fit, but I would still be limited to 1/2" tooling.

Look for the review in 2 - 3 weeks. I expect it will be very long so will take a while to write.

-Josh


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## atunguyd (Jan 17, 2015)

I have an axa on mine. If feels right in that the toolpost almost covers the end of the carriage (ie it's footprint is about the same size as the original 4 way post). I am not sure how much bigger a bxa will be. 

It's it a problem that you are limited to 1/2 tooling? On this size lathe you really don't need to go much bigger as you probably are not going to be doing such heavy cuts anyway.  For hss going bigger just means more cost and more time at the grinder sharpening the tool. 

On my SC8 I am pretty much using 10mm tools and getting good results. 

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## darkzero (Jan 17, 2015)

BXA is most likely too large for this size lathe. To be sure you'll need to check compound slide to spindle center line height. You'll need at least 1-1/8"+ height for BXA using 5/8" tools. I was going to purchase a PM1127VF & BXA was too large for it.

BXA is generally better suited for 12x-14x lathes. AXA generally covers 9x-12x lathes. Using a BXA without the ability to use 5/8" shank tools really has no benefit over a AXA. You'll just be paying more for the tool post & holders. I have a BXA on my 12x, while most of my tools are 5/8" I also use 1/2" & 3/8" tools which are more than adequate for an 11x lathe. My 12x using 5/8" tools sit at the bottom of the tool post so I doubt a BXA is good for the SC8.


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## atunguyd (Jan 17, 2015)

I will try to measure compound to centre line height tonight if you want. 

New versions come with a threaded home in the compound and not the bose as described in the minilathe.com review. 

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## joshua43214 (Jan 17, 2015)

Thanks for the replies. 
I had planned on using 1/2" or even smaller tooling. I was just hoping for some more mass, and the ability to use taller cut-off blades and longer boring bars. I know I will be parting some 2" steel and boring some holes ~ 2 1/2" deep in cast iron and bronze.

I will just go with the AXA then, it will be good for 99% of anything I will do. I can make up a dedicated post that replaces the compound if it turns out to be a problem.

Winter has closed in here, I'm hoping for one of our random Ohio temp swings to melt everything. My driveway is ~150' feet long and is rough before it is covered in snow/ice. DroPros told me they will drop it in the street, and will not take the truck onto my property. I have a crane modeled after an engine hoist that uses 12" tires for moving boulders around my yard. I haven't used in it several years, hopefully it still works.

-Josh


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## atunguyd (Jan 17, 2015)

Ok measured and carriage to center height is 1" 


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## joshua43214 (Jan 17, 2015)

atunguyd said:


> Ok measured and carriage to center height is 1"
> 
> 
> Sent from my GT-I9505 using Tapatalk



Excellent, thanks.
Looking at the schematics, the BXA would fit, but be limited to 1/2" tooling.
Seems the BXA would be over-sized then, I don't think the awkwardness of the BXA is worth it for the added mass.

Thanks again, this keeps me from trying a BXA then dealing with shipping it back for an AXA 

-Josh


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## atunguyd (Feb 4, 2015)

Hi Josh 

Did you get the lathe? What are your thoughts?


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## Franko (Mar 5, 2015)

Josh, I'd be interested in your thoughts on your SC8 too. I'm thinking about getting one.

Or, anyone else's thoughts would be good, too.


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## atunguyd (Mar 6, 2015)

Franko, I got my SC8-PRO a few months back and am very happy with it (coming from a 7x12). Feel free to bounce questions my way.


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## Franko (Mar 6, 2015)

Thanks, atunguyd. How do you think Sieg compares with Precision Machine tools? PM has an 11x27 large bore that looks very good to me. Plus, I kinda like the mechanical switches and pots better than inscrutable (if they malfunction) touch pads.


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## atunguyd (Mar 6, 2015)

Sorry mate I am located in south Africa so I do not know the PM range. I also prefer knobs to buttons but the buttons are not bad and this is not the first time sieg have used this system so one would assume they have the bugs resolved by now.


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## uberlinuxgeek (Mar 12, 2015)

Just want to mention. Don't buy from Bolton  I have been struggling for a year to get the gears that should have been with the lathe. Their support stinks on their products. Lathe is fine but with no after support you could get in a bad place if things break or missing items.


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## DKmachine (Apr 17, 2015)

greetings from Texas, I have been using this lathe for a year now. I will get back in a bit with info.


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