New to me - Colchester Triumph

[Lewis_RX8]

You need to get the gauge on the spindle nose behind the chuck - the way you're doing it you'll be measuring bar flex and chuck movement. I would measure cold and then repeat warmed up.

Like this ?

Should I just spin it and measure runout or try and flex it in some way?

Thanks

 

[Pete.]

When you're checking for loose bearings do it by lifting up on the chuck not barring it front to back. You'll be lifting against the weight then and any looseness will cause a jump in the needle.

 

[Hood]

It is hard to tell from pictures but I think you are just seeing the feed lines. You will always get them, how far spaced out will depend on the nose rad and the feedrate. Material also plays a big part in how visible they are.

 

[daedalusminos]

Like this ?

You need something in the spindle to act as a lever and have the gauge perpendicular to the axis for an accurate reading.

Mount the gauge on the headstock contacting the top of the spindle behind the chuck

 

[Hood]

Here is an example of what I am saying.
Both were same insert, same spindle speed, same depth of cut, same feedrate.


First is some kind of mild steel, no idea exactly what.

Next up is a piece of F51

 

[daedalusminos]

Next up is a piece of F51

That's such a good finish the camera was unable to focus

 

[Hood]

It wasn't so much the finish as the shine, I have messed around with the LED light and I now have a better pic showing the feed lines are still there.

 

[Hood]

Ok a drawing in fusion.
Tool rad 0.8mm
First part is 0.3mm/rev, second is 0.15mm/rev.
As can be seen grooves there but much less pronounced at the lower feedrate.

 

[Lewis_RX8]

Here is an example of what I am saying.
Both were same insert, same spindle speed, same depth of cut, same feedrate.


First is some kind of mild steel, no idea exactly what.
View attachment 325671


Next up is a piece of F51


View attachment 325672

Ah okay that is very simillar to what I was seeing, Especially on the mild steel which is what I have been using.

When you are talking about the material I do not get the same line issues with aluminium so maybe need to get ahold of some proper free machining steel. When I was turning the tool down to get it to fit to my lathe it made a lot of hot sparks but the harder material left a really and smooth nice mirror finish with little lines.

When you're checking for loose bearings do it by lifting up on the chuck not barring it front to back. You'll be lifting against the weight then and any looseness will cause a jump in the needle.

Thanks was not sure on the correct procedure

Ok a drawing in fusion.
Tool rad 0.8mm
First part is 0.3mm/rev, second is 0.15mm/rev.
As can be seen grooves there but much less pronounced at the lower feedrate.



View attachment 325679

Does make alot more sense now thanks , I suppose you have to find the balance as too slow a feed rate the insert wont work hard enough and too fast will create threading like line finish.

So these grooves I see are not "too" big a deal really and would be okay finishes for most parts?

 

[m_c]

Some metals are just a pain to get a good finish on.

Looking at the pictures, the finish looks more like too small a cut, and/or poor chip clearance.
For carbide cutting steel, I always take the approach that if the chips aren't at least straw coloured when they come off, then I'm not cutting hard enough.

You might also want to check that the insert edge is slightly above centre.

 

[Pete.]

I was going to suggest similar. That machine's a work horse, so horse that bitch and see what sort of finish you get then.

 

[Sean64]

You could try turning the tool upside down and take a cut with the chuck running clockwise (reverse) . The more I look the more it looks like feed marks . Highest speed lowest feed-rate small radius on tool ,I would use a sharp HSS tool less cutting pressure . Results would be interesting to see . The cutting pressure would be downwards onto the spindle bearing not upwards in the normal way .If the bearing does have some play it won't show in the finish the same .... I'm probably wrong but hay-ho

 

[Hood]

Mild steel will mar and rip as it cuts, higher alloy steels will cut better with less ripping. Aluminium and stainless are more ductile so tend to leave a really nice finish as they sort of smear.

The problem with going too low on the feedrate is you will get long stringy swarf which will mar the surface of the material you have just cut.

 

[Sean64]

Wow thanks for all the help on this folks

Pretty sure the belts are not the issue as same problems with running 1 belt as with running 3 and they are matched so no issues there.

@Munkul I know what you mean with the insert that was a photo from before I knew better just to show the finish , I was trying some of those ultra sharp alloy inserts and it still gave a line finish on lowest feed rate but it did feel smooth to touch just not a ground type finish others experience with them.

This is the alloy VCMT finishing insert result, Some of the Kennametal 0.4 radius inserts gave a nice finish but still lines unfortunately.

View attachment 325645

@prepman yes I am less inclined to fiddle with bearings when messing them up would pretty much scrap the lathe lol. Will have to try the play test once the lathe is warmed up aswell see if that changes the amount of play.

@Fortis maybe should have a go at the black art HSS sharpening


Intresting idea , The vibration is worst when the frequency was about 40hz which equated to near 1000RPM. When above and below the vibration is a lot less so this is certainly worth considering.




Intresting to have it rub slightly rather than cut , Would you have any photos of the grind on the tool as I say I have only ever used carbide. My motor is mounted in the lathe cabinet.


Coolant pump is nearly set up but will have a go without it and post some pics.

@Johnnybravo Good call on the levelling , I had a loose foot which made vibrations even worse that is snugged up now and I am hopeful that the vibrations are not caused by a bent spindle as they are worse at 1000RPM at full speed 1200RPM they still vibration but less so where as I imagine a with a bent spindle the faster it is the worse it is.

Just make sure once you've ground to the desired profile you spend time honing the cutting edges ,I use a diamond hone .

Sean

 

[Ubique]

@Lewis_RX8 do you know anyone that could lend you some 'chassis ears' basically they're an electronic stethoscope that can display the vibration frequency, amplitude and in some cases, direction to source. It may also be worth looking at the motor mounting and putting a DTI on the motor casing to see if there is any deflection worth worrying about.

 

[Lewis_RX8]

@Lewis_RX8 do you know anyone that could lend you some 'chassis ears' basically they're an electronic stethoscope that can display the vibration frequency, amplitude and in some cases, direction to source. It may also be worth looking at the motor mounting and putting a DTI on the motor casing to see if there is any deflection worth worrying about.

Hmm I could do a screwdriver to the ear that my fancy stethoscope lol, Seen some SKF condition monitoring stuff that is like that really nice bits of kit now over Bluetooth and can look at logs of vibrations and frequencys quite fancy.

 

[Ubique]

Hmm I could do a screwdriver to the ear that my fancy stethoscope lol, Seen some SKF condition monitoring stuff that is like that really nice bits of kit now over Bluetooth and can look at logs of vibrations and frequencys quite fancy.

If it's rebadged 'Steelman' kit, it's shi'te, otherwise if you can get hold of a loan or demo kit, it should help.

 

[roofman]

I find if i am turning a bar of "draggy" steel that's giving feed lines i just max the chuck speed out and go really fine on the cut with sharp HSS...really helps things out.

 

[Richiew]

I was getting lines like that on my much weedier lathe. Tried HSS with a fat radius and managed better. Stay away from pointy carbide.

12mm diameter.

 

[Ubique]

Like this ?

Should I just spin it and measure runout or try and flex it in some way?

Thanks

You won't get a true run-out measurement like that, the DTI should be at 90deg. to where you want to measure the run-out, that looks to be roughly 45deg, which will give you an indication, but not a true measurement.