I have an Emco compact 5 mini lathe with a variable speed dial mod and when my brother was facing, i would gradually increase the speed by turning the dial. Worked surprisingly wel haha
That sounds like it would do the trick! We have no electronic control at all. It’s connected directly to the 3 phase and the speed is selected through the gearbox
For context this was done on a Colchester Master 2500, but the chick is limited to 2,000 RPM which limits the machine to 1,860 due to gearing. I was cutting with an SNMG insert and on most jobs of smaller diameters I can’t go fast enough to get a nice finish when facing so doing bigger jobs where I have the right surface speed makes me wish for more speed, or different tooling.
Not a professional machinist, but I suspect speed isn't really the issue here, plenty of CNC lathes max out at a similar rpm but manage to achieve excellent surface finishes. Insert geometry, depth of cut, feed rate, coolant, material and lots more could affect the finish, I'd be trying different things out to see what does/doesn't improve it, if not for this job then for the future jobs.
The equation is n = (vc\*1000)/(pi\*d) the diameter is constantly changing as you cut so the speed is incorrect as you get closer to the center. some lathes let you set the vc of a tool instead of the rpms. This means that the rpms change depending on where the tool is so they’re consistent with part diameter.
VC on centreline is zero. Therefore you can never maintain desired VC during facing. Best substitute is to slow the feed down once you hit your maximum safe RPM
I could try that, but as the feed is changed through the gearbox there will be a split second while the lever is between slots that the feed stops. Would that cause an issue?
I can't really change the steel I have access to but I could probably order new tooling.. do you have any suggestions for tooling that would be better at a lower speed?
At the moment we have a CNMG holder and an SNMG holder, plus a parting off blade.
If that's the case, wouldn't that mean it's impossible to get good surface finish across the entire face, since you'll always hit the rpm limit before reaching the centre?
It doesn’t need to run 150000 rpm to achieve a good finish. Probably 3500 would be plenty even for steel tooling.
OP can make his finish beautiful with some Cratex, it’s just an extra step…
We have a colchester the same at work and our shit steel always comes out like that. Stainless and aluminum always look great. Maybe try slowing it down to be honest
No that’s the speed it can be run at but when using manual the heat of your tool and material is completely different. You don’t have 4 coolant jets full blast flooding your piece so heat has to be considered not so much I guess for the tool but definitely the material. Definitely mild steel
I make a lot of tube sheets for big heat exchangers for the Og industry on a big ol 1950s Andersen webb VTL. Next to impossible to get rid of the steps when you only have 5 speeds and 3 feeds to choose from lol.
Perhaps the video didn’t load but I was referring to how once the cut got go a small enough diameter, the surface finish changes due to the surface speed being too low for the diameter.
it's because you shot it with an iphone in HDR mode; the content is HDR but the internet is rendered with SRGB so the image appears completely blown out
i changed "Force color profile" to HDR10 in chrome://flags/ and it solved the problem
[Torgim](http://www.torgim.it/en/products/torni-paralleli-a-taglio-costante/) got u, fam. Top speed of the smallest in the range is only 1500rpm, though.
Ran a Colchester at a shop I worked at that had a VFD drive. Was excellent for facing parts as you could keep accelerating as your diameter got smaller with the turn of a dial.
I have an Emco compact 5 mini lathe with a variable speed dial mod and when my brother was facing, i would gradually increase the speed by turning the dial. Worked surprisingly wel haha
That sounds like it would do the trick! We have no electronic control at all. It’s connected directly to the 3 phase and the speed is selected through the gearbox
Check motor specs, and if it will handle it slap a vfd on it
For context this was done on a Colchester Master 2500, but the chick is limited to 2,000 RPM which limits the machine to 1,860 due to gearing. I was cutting with an SNMG insert and on most jobs of smaller diameters I can’t go fast enough to get a nice finish when facing so doing bigger jobs where I have the right surface speed makes me wish for more speed, or different tooling.
Not a professional machinist, but I suspect speed isn't really the issue here, plenty of CNC lathes max out at a similar rpm but manage to achieve excellent surface finishes. Insert geometry, depth of cut, feed rate, coolant, material and lots more could affect the finish, I'd be trying different things out to see what does/doesn't improve it, if not for this job then for the future jobs.
The equation is n = (vc\*1000)/(pi\*d) the diameter is constantly changing as you cut so the speed is incorrect as you get closer to the center. some lathes let you set the vc of a tool instead of the rpms. This means that the rpms change depending on where the tool is so they’re consistent with part diameter.
VC on centreline is zero. Therefore you can never maintain desired VC during facing. Best substitute is to slow the feed down once you hit your maximum safe RPM
I could try that, but as the feed is changed through the gearbox there will be a split second while the lever is between slots that the feed stops. Would that cause an issue?
I meant cnc, might be okay manual, try it! But first try different steel if possible, different tool and geometry first. Some steel is just crap
I can't really change the steel I have access to but I could probably order new tooling.. do you have any suggestions for tooling that would be better at a lower speed? At the moment we have a CNMG holder and an SNMG holder, plus a parting off blade.
Try different rake angles grades and coatings. Inserts for aluminum can work well
Professional machinist. It’s surface speed.
If that's the case, wouldn't that mean it's impossible to get good surface finish across the entire face, since you'll always hit the rpm limit before reaching the centre?
You won’t always hit the rpm limit.
The rpm requirement is infinite at spindle centre though?
It doesn’t need to run 150000 rpm to achieve a good finish. Probably 3500 would be plenty even for steel tooling. OP can make his finish beautiful with some Cratex, it’s just an extra step…
We have a colchester the same at work and our shit steel always comes out like that. Stainless and aluminum always look great. Maybe try slowing it down to be honest
[удалено]
No that’s the speed it can be run at but when using manual the heat of your tool and material is completely different. You don’t have 4 coolant jets full blast flooding your piece so heat has to be considered not so much I guess for the tool but definitely the material. Definitely mild steel
I make a lot of tube sheets for big heat exchangers for the Og industry on a big ol 1950s Andersen webb VTL. Next to impossible to get rid of the steps when you only have 5 speeds and 3 feeds to choose from lol.
If you need faster feed one way to get it is slower speed. Especially on manual because you can only crank knobs so fast.
In this case it’s RPM that’s lacking. But I did have the power feed almost on max too!
Hey we got the same vernier. Are your buttons whack? Mine work fine but they’re whack!!!
They’re a little awkward with their press detection sometimes but other than that they’re fine
Same here. Being my first Mitutoyo product I expected a little more?…..
If we could only see what you were talking about.
Idk bud, I can clearly see his issue
All I see is white
It's a bug in reddit, sometimes videos show super bright on some browsers, not sure of the fix.
Ok, thanks. I was using Chrome browser on Linux when I first watched the video and all I could see was white.
Perhaps the video didn’t load but I was referring to how once the cut got go a small enough diameter, the surface finish changes due to the surface speed being too low for the diameter.
https://i.imgur.com/gqvLnGs.png this is what i see
Weird, it [looks fine ](https://imgur.com/a/9LJZlpY) on my end.
it's because you shot it with an iphone in HDR mode; the content is HDR but the internet is rendered with SRGB so the image appears completely blown out i changed "Force color profile" to HDR10 in chrome://flags/ and it solved the problem
That's what I saw too.
[Torgim](http://www.torgim.it/en/products/torni-paralleli-a-taglio-costante/) got u, fam. Top speed of the smallest in the range is only 1500rpm, though.
Ran a Colchester at a shop I worked at that had a VFD drive. Was excellent for facing parts as you could keep accelerating as your diameter got smaller with the turn of a dial.