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[4]

Sieg 7x clone Half-Nut

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Mrfix71

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#1
Several years ago I bought one of the asian mini-lathes off of Ebay, settled on this one because they all all looked the same, but this one was listed as longer...as a 7x16". I believe it was a Big Dog or Real Bull or something like that, but there are no ID markings (the control housing was crushed in shipment and I agreed to a generic un-labeled replacement sent out for expediency. Since then, I have replaced the hi-Low gears from LMS and bought several various accessories/tooling.

The problem I am having is that one of the half nuts broke. Looking on the internet, I could not find the same style since the common Sieg half nuts have a pin the the back which fits a groove in the cam. On mine, the operation is reversed where the cam has pins and the half nuts have slots.

To try and replace the broken half-nut ans well as for unknown future reasons...does anyone know who made this machine and parts? I welcome any assistance.
 

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markba633csi

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#2
Perhaps you could have the broken part filled with braze metal and recut the slot? Also I would ask LMS if they could order those for you or point you to a source?
Mark
 

The_Apprentice

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#4
I believe it was a Big Dog or Real Bull or something like that,-
Does Big Dog Metal Works seem more familiar to you?

I could be wrong, but they may be defunct now adays... But they did have the 7x14...
 

clevinski

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#5
Hi...

If you got the lathe from Big Dog Metal Works, it is a Real Bull, not a Sieg. I have the same lathe. While the Sieg lathe is more popular in the U.S., the Real Bull is more popular in Europe. Many consider the Real Bull a slightly higher quality lathe.

I would suggest you contact Amadeal Ltd. In the UK (http://www.amadeal.co.uk). They supply parts for the Real Bull, and are very knowledgeable and helpful. They have shipped to me here in NJ before with no difficulties.

Good luck!

Charlie
 

Mrfix71

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#6
So Real Bull is a Big Dog product? I was under the impression they were two different manufacturers. Go figure!

I had the idea of filling and recutting the slot, but did not like the force being placed on the thin cast iron wall . The opposite design seems so much stronger. My attempt to repair the slot anyway were failing and I stopped before I destroyed the original. Seemed easy enough!

I contacted LMS and, understandably, could not guarantee the parts they carry fit. Since I posted here last, I did receive the half nut and cam set from LMS. This machine very well may be a Real Bull. Mine is 7x16 (the leadscrew measures 28" long). Unfortunately, there re no factory markings anywhere and we have not been able to recover any purchase information from 2012 when it was bought. I did see the slotted cam at Amadeal, but not the half nuts.

Since I posted, I did receive the half nut and cam set from LMS. The half nuts themselves were the same dimensions, but have the pin. The slotted cam's face was much larger in diameter than mine. After a while of debating, I turned down the cam to fit the apron. After a while longer doing extensive measuring, checking, and trial fitting...I redrilled the half nuts and moved the pins over a bit. It was binding up real bad, but with some lapping, the mechanism works fine! The only problem is that the lower nut is now barely clearing the leadscrew when unlocked. It looks as if I were to shave the top of the apron, not only would there be enough clearance with the halfnuts, but the meshing of the handwheel gear to track will be improved as well. I am going to add some detents to lock open or closed as well.

Thanks fellas!
 

clevinski

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#7
Big Dog is a distributor, and they were, for a time, the exclusive Real Bull distributor in the U.S. I have the manual for my Real Bull, which I can email you if you wish. I am not sure how useful it would be, but I'm happy to do so.

Best regards,
Charlie
 
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