Sieg SC3-400 upgrade progress

[Drew Mason 1Participant @drewmason1]

Hi All

Gary – don't concern yourself with the deleted posts. Its not a problem. It is annoying, but that is all it is.

JasonB – I have no problems with anyone posting on this thread. As i repair the lathe i will be more than happy to hear what i am doing wrong and learn from it. It is, after all the great thing about forums. The way different people come together to work through the same problem.

Emgee – well it is a forum and that does happen.

JasonB – the motor is far too large to take up the same position as the original motor.

Will update post soon. May make a little video to explain why the repair is not so straight forward if i get time. Its an interesting one though and will look forward to hearing from you all.

Best regards,

Drew

[Drew Mason 1Participant @drewmason1]

Haha! just noticed the hijacker is back posting to the thread. I'm so glad to know that my concerns were understandable to you. They would have been understandable to everyone had you not deleted them, but now they are gone forever…

Unless..

[SillyOldDufferModerator @sillyoldduffer]

Posted by Drew Mason 1 on 17/03/2022 14:29:45:

Haha! just noticed the hijacker is back posting to the thread….

Just for the record Ketan is one of the forums most valued posters, certainly not a 'hijacker'.

Dave

[Drew Mason 1Participant @drewmason1]

Hi Dave,

I have just received a call from Ketan who manned up and apologised for his behaviour on this thread. Total respect to the man.

Regards,

Drew

[garyParticipant @gary44937]

alls well that ends well

[Mike PooleParticipant @mikepoole82104]

Nothing removed by me.

Mike

[Neil WyattModerator @neilwyatt]

Hi folks, no drama, Ketan had a word with MTM's IT department, as he couldn't reach me (I have now switched off my "I've got covid and feel poorly, let me be" auto responder).

Neil

[Drew Mason 1Participant @drewmason1]

Ok so quick update on the Sieg sc3 lathe repair.

The plan is to move the motor from its current position and extend the shaft so I can position the spindle in roughly the original position thus enabling me to refit the thread cutting gears and cover.

Milling the keyway on the pedestal drill is always hilarious but I just about got away with it. Bit of packing and araldite. It's not going to move.

I think I may have made the extension a little too short so going to turn another longer one just incase. Once the motor has been removed for fitting the extension to the lathe I'll be using part of the welded bracket (that the motor currently sits on) for positioning those lovely green bearings! hopefully it'll work out OK 👍

More to follow..

[Drew Mason 1Participant @drewmason1]

Hi All,

Been a little busy with work so progress has been a little on the slow side but here's where i am now.

The motor shaft extension was a little to short so remade with plenty to spare! Fun and games at distance. As it turned out i had slightly lost my centres at this point but not to worry.

I think i had probably only excentuated the run out of the chuck but for a first attempt it went well enough.

Tapped the pulley end of the extension as i have another piece which goes over this and then through the machine side bearing.

These nice, highest quality (magnetic) stainless bolts for the bearings could be carefully welded with normal A15 tig filler. They're solid!!

Extension mounted through the bearings. I am expecting these to move a little when welded to the main plate that fastens to the lathe so what you cant see from this image is that i have a lot of options to raise and lower the bearings as well as more than enough front to back to get things lined up properly.

A quick mill for the key. I did both ends. The motor end is completely through.

Jigged up ready to weld. Everything seemed so easy!

Plenty of room for the thread cutting gears. So just a bit of cover cutting and the whole things is back together..

Fix 1 – More to follow..

[HopperParticipant @hopper]

Good stuff. Looks like one heck of a motor for that little lathe but should solve the issue of the smoke getting out of the controller cards.

[Drew Mason 1Participant @drewmason1]

Thanks Hopper. Fingers crossed that's the end of the blown and smoking motor control boards. The original sieg lathe was wired out of phase when I bought it (unbeknown to me until it blew) which fried everything before the fuse which was effectively in the neutral conductor. Very annoying and extremely dangerous!!

These three phase vfd's are a superb alternative and so far performing excellently. I have an update to follow shortly when I get a minute away from work 👍

[Dave HalfordParticipant @davehalford22513]

That's a good place to fit a dog clutch

[Drew Mason 1Participant @drewmason1]

Now that is a fabulous idea Dave..

[JasonBModerator @jasonb]

If you made it a double dog so it's like a Huco Coupling that would also allow for any slight misalignment between motor and extension shaft that could cause vibration.

[SteviegtrParticipant @steviegtr]

Great work Drew.

Steve.

[Ron LadenParticipant @ronladen17547]

Drew, the motor and VFD will be fine and nice to use the only thing I would say is to keep in mind that it is a mini lathe and its just a fact of life they are not the most rigid of machines. Not knocking the mini lathe its how I started and it served me well and I did some nice work on it but they do need keeping within what they are capable of. Thats quite a motor which will deliver quite a bit more than the original so just be careful to not let that lead you into asking more of the machine than it can cope with.

I stalled my mini lathe whilst parting some steel and the deflection the tool post went through when the parting tool jammed was scary to see and I broke the plastic gears in the head. I know yours doesnt have the plastic gears but you wouldnt want the damage elsewhere which could be more serious.

I replaced the head gears with a steel set and at the time Jason suggested changing from the toothed belt to a Poly multi V belt which when adjusted correctly gives good drive but if the machine was stalled or crashed the belt would slip helping to prevent damage. It was just a thought seeing the toothed belt drive with a more powerful motor on yours. A picture of the belt and drive pulleys below, the pulleys I had to turn up as I couldnt find off the shelf ones of the correct size.

It was just a thought but you may be quite happy with what you have gone with.

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