Rexvalter VF-118 lathe (was: old Myford Ml7)

[DennisCA]

On the practical side, it was pretty much useless. Too much flex. I am wondering if a small hole like this is too small to single point thread. Maybe a tap is needed.

 

[Hood]

Tap would be quicker and easier but I have single pointed threads as small as M5.

 

[DennisCA]

Whatever this material is (mystery material from a junkpile) it seems pretty hard, maybe that's why it doesn't seem to want to take.

 

[Hood]

I would say your threading bar that you made has far too much overhang. I don't know how much your carbide insert bar had but you should keep the unsupported overhang to an absolute minimum. In other words if you are threading to a depth of 10mm then on a manual lathe I would try for a max of 15mm unsupported.

 

[DennisCA]

That does look to be the case. I looked through the drawer of stuff that came with the lathe and found a small internal threading tool (hss, round bar with brass square holder), it was quite rigid and allowed me to get a thread, but it's too shallow. At least it showed that it's possible so I will try and make a new threading tool capable of coarse grind, using a round bar instead. But then I need to make a holder.

At any rate the HSS stuff seems to hold better than carbide. I've broken several inserts now on multiple tools from my banggood set. I got a replacement set coming but it's the same chinese quality so it might not last long. I need to research what quality inserts it's worth getting, they are just so pricey...

 

[Hood]

HSS is more tolerant of a less rigid setup but won't last that great in tough materials.

 

[Hood]

Also don't base your thoughts of carbide tools on cheap ones especially when it comes to threading.

 

[DennisCA]

Storebro (manufacturer) got back to me on a really old mail I had forgotten about. According to them I don't need to get special CL7C bearings for the lathe, they mean modern J2/Q bearings of a good brand like SKF are as good as those P5 classified bearings from the 50s. That's a relief if so, no need to hunt expensive hard to find bearings if that becomes in issue.

I also realize I have never looked into the gearbox, I have no idea what the inside condition is and I think the only way to get it out is turning the lathe out again from the wall so I can access it form behind, who knows what the oil level is, or what state it might be in.

Le sigh as the french say (I made that up).