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

[DennisCA]

Well I put the coolant issue on hold for now, took apart the apron and removed the saddle and cross slide to drill and tap for oilers. This was some of the more butt clenching things I have done.

Not as pretty as Stefan Gotteswinters work which was my inspiration here. I did not make a push fit of the oiler either but used loctite(s cheap cousin).

 

[DennisCA]

Drilled and installed four oilers on the saddle last night. Tested and they all seem to work as planned. I need to clean the heck out of the parts and put everytihng back together now.



So back to the coolant system. Any input on designing the coolant system?

If it was you, would you simply connect the drain line back to the pump and let it recirculate the coolant directly? Maybe fit some kind of filtration system to remove the worst gunk? Or would you direct it to a separate tank so you have to manually refill the pump tank every time, and then also filter it / skim off nasty things.

I don't know how actual systems that are in use current are designed so I am fumbling a bit.

 

[addjunkie]

Tank, centrifugal pump, up through flex pipe to the nozzle, valve before the nozzle. Coolant runs off into drip tray, drip tray has mesh filter to catch swarf, runs back to tank. Simple nothing complex

An off the shelf example for retro fit

http://www.warco.co.uk/coolant-systems/302973-independent-coolant-system.html

 

[DennisCA]

Yeah seems my setup then is very complete. Basically all I need are hoses. Oh and coolant.

 

[DennisCA]

Recorded a video to help gauge the sound of the lathe. I removed the secondary shaft and disconnected the drive to the threading gearbox to reduce irrelevant noise.

First with the lever in high speed position, then hovering in the middle (very silent then) and then in low speed position. I am pretty sure it's the lever actutator or some components in it interacting with the shaft that causes the noise.

 

[DennisCA]

Cheap chinese carbide kit I ordered came:

Seems to produce OK results:

 

[DennisCA]

Continuing with my experiments, this piece of steel is really hard to get a good finish on, I have no idea what it is, a 20mm rod of some kind.

Both HSS and carbide (WNMG) left very ugly results on this piece of unknown metal. Oil did not help the finish with carbide, nor did soluble oil cutting fluid, tried different speeds and cutting depths. Only with HSS and a lower RPM with cutting fluid did I achieve a resonable finish.

The thicker part is what both the carbide turned out like, the narrow pass was the best I could achieve with a round nose HSS bit and cutting fluid in a spray bottle. The cutting fluid really helps, also prevents edge build up. I don't have any proper sulfur cutting oil, just this old fashioned motor oil I am using for general lubrication on this lathe so that might be a reason the oil isn't doing much, does seem to help plenty though when parting.

 

[Windy Miller]

Try grinding up a bit of hss into a vertical shear tool. You will only be able to take off about 1 thou with it, but it should produce a lovely finish even on really rubbish steel. Perfect for the finishing cut.

 

[DennisCA]

Yeah I've been meaning to try that out. The biggest problem I got is not enough QCTP holders, getting annoying to switch between them and having to reset the center height. I wish I had like 10 more, only got 4

And they're an odd swedish design so I am gonna have to make my own I think. But no mill......

 

[Windy Miller]

Yeah I've been meaning to try that out. The biggest problem I got is not enough QCTP holders, getting annoying to switch between them and having to reset the center height. I wish I had like 10 more, only got 4

And they're an odd swedish design so I am gonna have to make my own I think. But no mill......

You can never have enough QCTP holders!

 

[DennisCA]

Broke a parting tool this week trying to part of a 60mm piece of round stock. It's an HSS based parting tool. Based on a the recommendation of a nearby machinist I acquired this kit instead of buying more HSS (12x3mm profile), it is 2mm instead:

https://www.ebay.com/itm/SMBB2032-C...244964?hash=item4b16c03ee4:g:T~gAAOSw~y9ZCpi8

https://www.ebay.com/itm/10pcs-SP20...690132?hash=item1c8208a9d4:g:ZBAAAOSwXetZO8iT

 

[DennisCA]

Tried to thread an internal 3/4-10" thread today. Using a banggood kit I have bought with all kinds of inserts, I have been mostly satisfied with it so far but the internal threading bar just kept breaking the inserts, I am now all out of inserts. I am wondering if I am doing something wrong.

I had the compound at 29.5 or 60.5 degrees depending on how you look at it. The threading insert was on center. I zeroed the cross slide and compound slide, engaged the nut and took my first pass, then I stopped the lathe and backed out the cross slide and reversed it, then I advanced 5/100ths of a millimeter or two thousands. I only had the one carbide insert and I went through all three without the thread getting done. So I don't know, any obvious errors in my method? Is two thousands too heavy a cut?

 

[Hood]

Most likely useless inserts. I usually go for 0.25mm DOC (0.5mm on dia) for the first pass then drop down to 0.1 for the rest and that is in 316 or F51, on brass I usually stick at the 0.25 DOC..
I have never offset my compound whether internal or external but everyone has their own ideas on that.

 

[Hood]

BTW the rigidity of the threading bar may also be an issue or even the security of the insert in the seat.

 

[slim_boy_fat]

Try grinding up a bit of hss into a vertical shear tool

Just been reading about them. Looks like I'm going to have to grind one for dealing with those 'diiicult' materials.

 

[DennisCA]

The setup seemed as rigid as you could expect from a 12mm shank tool, the inserts are called IR11, googling that gives some options though I am not sure they are compatible or not, but I assume they are, indystry standards and all that. But for now I am gonna try grinding my own internal threading tool from a piece of square HSS.

 

[Hood]

How much stickout did you have, you should try and keep it to just slightly more than the depth you will be cutting so as to keep things as rigid as possible.
The IR11 inserts should fit fine.

 

[Windy Miller]

Just been reading about them. Looks like I'm going to have to grind one for dealing with those 'diiicult' materials.

I had a go with one a while ago, and they really are as good as they're made out to be. Super easy to grind too, but you can only take the lightest of light cuts.
Really handy when you run out of steel wool too!

 

[DennisCA]

Preliminary layout:

 

[DennisCA]

Man that was a PITA to hog out that material, wore out a 36 grit belt on that

I checked and I will have to relieve the bottom of the cutting profile or it won't fit into a pilot hole for a 3/4 threaded hole.